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760,819 | I have a very simple program written in 5 min that opens a sever socket and loops through the request and prints to the screen the bytes sent to it.
I then tried to benchmark how many connections I can hammer it with to try to find out how many concurrent users I can support with this program.
On another machine (where the network between them is not saturated) I created a simple program that goes into a loop and connects to the server machine and send the bytes "hello world".
When the loop is 1000-3000 the client finishes with all requests sent. When the loop goes beyond 5000 it starts to have time outs after finish the first X number of requests. Why is this? I have made sure to close my socket in the loop.
Can you only create so many connections within a certain period of time?
Is this limit only applicable between the same machines and I need not worry about this in production where 5000+ requests are all coming from different machines? | 2009/04/17 | [
"https://Stackoverflow.com/questions/760819",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/79567/"
] | The quick answer is 2^16 TCP ports, 64K.
The issues with system imposed limits is a configuration issue, already touched upon in previous comments.
The internal implications to TCP is not so clear (to me). Each port requires memory for it's instantiation, goes onto a list and needs network buffers for data in transit.
Given 64K TCP sessions the overhead for instances of the ports might be an issue on a 32-bit kernel, but not a 64-bit kernel (correction here gladly accepted). The lookup process with 64K sessions can slow things a bit and every packet hits the timer queues, which can also be problematic. Storage for in transit data can theoretically swell to the window size times ports (maybe 8 GByte).
The issue with connection speed (mentioned above) is probably what you are seeing. TCP generally takes time to do things. However, it is not required. A TCP connect, transact and disconnect can be done very efficiently (check to see how the TCP sessions are created and closed).
There are systems that pass tens of gigabits per second, so the packet level scaling should be OK.
There are machines with plenty of physical memory, so that looks OK.
The performance of the system, if carefully configured should be OK.
The server side of things should scale in a similar fashion.
I would be concerned about things like memory bandwidth.
Consider an experiment where you login to the local host 10,000 times. Then type a character. The entire stack through user space would be engaged on each character. The active footprint would likely exceed the data cache size. Running through lots of memory can stress the VM system. The cost of context switches could approach a second!
This is discussed in a variety of other threads:
<https://serverfault.com/questions/69524/im-designing-a-system-to-handle-10000-tcp-connections-per-second-what-problems> | Yep, the limit is set by the kernel; check out this thread on Stack Overflow for more details: [Increasing the maximum number of tcp/ip connections in linux](https://stackoverflow.com/questions/410616/increasing-the-maximum-number-of-tcp-ip-connections-in-linux) |
46,860 | How believable is a touch or fluid vectored bacteria which is so dependent on its host that the remains of a terminated victim become non-contageous within minutes of the host's death?
I'm postulating an infector which consumes its host so quickly that infected blood samples contain no living infectors within an hour of the sample being taken. If such a thing is possible, how could such a disease avoid burning through its host's energy reserves so quickly that it doesn't have time to infect others? | 2016/07/10 | [
"https://worldbuilding.stackexchange.com/questions/46860",
"https://worldbuilding.stackexchange.com",
"https://worldbuilding.stackexchange.com/users/3112/"
] | Is there any evolutionary benefit to becoming non infectious minutes after inducing death?
Is this a naturally occurring disease or an engineered disease?
So lets try this:
The pathogen, in this case a yeast, infects the hosts blood. The yeast, as part of its normal metabolism, produces a protein that is sheds and which circulates in the blood stream. We will call this protein Cryptomamillian Coagulating Factor 1 (CCF-1). As CCF-1 circulates in the blood, the kidneys and liver try to flush it. However, over the course of some time period suitable for your plot, the kidneys and liver begin to fail, with jaundice, shortness of breath, etc. being the symptoms. Once liver and kidney failure begin, the CCF-1 protein begins to build rapidly in the blood stream. Shortly there after, concentration of the CCF-1 protein reaches a point where a sudden and complete polymerization of the free protein occurs; essentially, over the course of a few seconds, all the blood in vessels and tissue converts to a semi-solid gel. This gel encases the yeast circulating in the body, rendering it harmless. The body can be handled with out much / any risk of infection. Only removing the gelatin blood, and grinding it up to release the yeast again would be sufficient to infect again. And it could be that the the yeast itself is rendered non-viable immediately when caught-up in the flash polymerization. Your choice.
If this is a natural item, perhaps it is occurring now because this was a yeast naturally occurring in a cold area, that has warmed due to climate change. Migratory birds new to the area due to warmer temps are the vector for the yeast to move into civilization.
Hopefully, you find something you can work with in this nugget. | A slightly different method is to make the infection method something tied to the host being alive, like respiration.
If the disease is spread air borne by breathing it will not spread from any dead host. |
46,860 | How believable is a touch or fluid vectored bacteria which is so dependent on its host that the remains of a terminated victim become non-contageous within minutes of the host's death?
I'm postulating an infector which consumes its host so quickly that infected blood samples contain no living infectors within an hour of the sample being taken. If such a thing is possible, how could such a disease avoid burning through its host's energy reserves so quickly that it doesn't have time to infect others? | 2016/07/10 | [
"https://worldbuilding.stackexchange.com/questions/46860",
"https://worldbuilding.stackexchange.com",
"https://worldbuilding.stackexchange.com/users/3112/"
] | Is there any evolutionary benefit to becoming non infectious minutes after inducing death?
Is this a naturally occurring disease or an engineered disease?
So lets try this:
The pathogen, in this case a yeast, infects the hosts blood. The yeast, as part of its normal metabolism, produces a protein that is sheds and which circulates in the blood stream. We will call this protein Cryptomamillian Coagulating Factor 1 (CCF-1). As CCF-1 circulates in the blood, the kidneys and liver try to flush it. However, over the course of some time period suitable for your plot, the kidneys and liver begin to fail, with jaundice, shortness of breath, etc. being the symptoms. Once liver and kidney failure begin, the CCF-1 protein begins to build rapidly in the blood stream. Shortly there after, concentration of the CCF-1 protein reaches a point where a sudden and complete polymerization of the free protein occurs; essentially, over the course of a few seconds, all the blood in vessels and tissue converts to a semi-solid gel. This gel encases the yeast circulating in the body, rendering it harmless. The body can be handled with out much / any risk of infection. Only removing the gelatin blood, and grinding it up to release the yeast again would be sufficient to infect again. And it could be that the the yeast itself is rendered non-viable immediately when caught-up in the flash polymerization. Your choice.
If this is a natural item, perhaps it is occurring now because this was a yeast naturally occurring in a cold area, that has warmed due to climate change. Migratory birds new to the area due to warmer temps are the vector for the yeast to move into civilization.
Hopefully, you find something you can work with in this nugget. | Viruses may be a loophole worth exploring. Scientifically they are not categorized as "living," so the only time you could even consider them alive is while their DNA is part of an infected cell churning out viruses. Thus, when the host dies, and their cells die with them, the virus "dies."
Alternatively, a disease which tries to cause spontaneous combustion or some similar runaway cycle could work.
One challenge you will have with this is that the definition of "death" on a cellular level is blurrier than just a few minutes. Our own cells can last [quite a while](http://health.howstuffworks.com/diseases-conditions/death-dying/dying4.htm):
>
> While the body as a whole may be dead, little things within the body
> are still alive. Skin cells, for example, can be viably harvested for
> up to 24 hours after death [source: Mims]
>
>
> |
23,070 | Is there any software/website you can use to Backup data from an FTP server to a cloud service like Onedrive, Dropbox or google drive (or something else)?
It takes some time to download the folder to your computer and then upload it to Onedrive. Which adds an unnecessary step in between (which often also is a bottleneck). | 2015/08/16 | [
"https://softwarerecs.stackexchange.com/questions/23070",
"https://softwarerecs.stackexchange.com",
"https://softwarerecs.stackexchange.com/users/16301/"
] | Actually, there're many apps/services that can do the backup like CloudHQ, Cloudsfer, cBackupper... CloudHQ and Cloudsfer are like cloud-to-cloud migration and cBackupper is more relevant to what you want, the [cloud backup](https://cloud.ubackup.com) thing. Besides, cBackupper also has the PC-to-cloud backup mode, but it seems like this function has not been released yet. | From the question it isn't really clear if the FTP server is "given" or if it's something you have the liberty to install and deploy yourself. In the latter case, you may consider to deploy your FTP (FTPS or SFTP) server directly in the cloud, which would inherently store your data in the cloud where you have deployed it.
One option is [SFTP.cloud](http://sftp.cloud), which runs on Amazon (AWS) and can be deployed in 1 click from the AWS Marketplace. This would, of course, store your data in the AWS cloud (not OneDrive or DropBox, which are more suitable for individual use as opposed to real enterprise-grade cloud services). |
23,070 | Is there any software/website you can use to Backup data from an FTP server to a cloud service like Onedrive, Dropbox or google drive (or something else)?
It takes some time to download the folder to your computer and then upload it to Onedrive. Which adds an unnecessary step in between (which often also is a bottleneck). | 2015/08/16 | [
"https://softwarerecs.stackexchange.com/questions/23070",
"https://softwarerecs.stackexchange.com",
"https://softwarerecs.stackexchange.com/users/16301/"
] | Actually, there're many apps/services that can do the backup like CloudHQ, Cloudsfer, cBackupper... CloudHQ and Cloudsfer are like cloud-to-cloud migration and cBackupper is more relevant to what you want, the [cloud backup](https://cloud.ubackup.com) thing. Besides, cBackupper also has the PC-to-cloud backup mode, but it seems like this function has not been released yet. | I am currently using MultCloud(based on the web) to sync my OneDrive files. Since I have not used FTP before, I can’t give you an exact answer, but I do see the FTP option there, so I guess it is supported by MultCloud as well. This app is very easy to operate for me, that’s why I’m still using it.
I moved to the MultCloud page just now and found a tutorial about how to migrate files from FTP to OneDrive for you, you may have a look if you are interested. Hope it can be helpful. [Transfer Files from FTP Server to OneDrive](https://www.multcloud.com/tutorials/transfer-files-from-ftp-server-to-onedrive-7283.html) |
645,714 | On my multimeter, the D.C. voltage readings get inaccurate over time due to battery discharge.
How can I tell when to change out the batteries?
By consulting the manuals, I found what is displayed when the battery needs replacement.
Thanks. | 2022/12/09 | [
"https://electronics.stackexchange.com/questions/645714",
"https://electronics.stackexchange.com",
"https://electronics.stackexchange.com/users/175334/"
] | Most meters will have a battery low indication. A good quality meter will have one that comes on before any readings start to become inaccurate.
If you have a variable power supply, you can test your meter by using that instead of the battery. Wind the supply voltage down, and note the voltage at which the low battery warning comes on. Do the same when measuring a constant DC voltage (of near full scale), and when measuring a resistor on ohms range. At what meter supply voltage do the readings change? | By consulting the manuals, I found what is displayed when the battery needs replacement. |
9,948 | What nonparametric "Model Free" methods exist to measure intraday seasonality? I would like to estimate intraday seasonality in any of
* The volatility
* The traded volume
* The bid ask spread
* or something as esoteric as the rate of orders with a frequency higher than a specified threshold.
One approach that I was going to explore was time series or sequential clustering followed by transition probability estimation.
Thank you for your time | 2014/01/15 | [
"https://quant.stackexchange.com/questions/9948",
"https://quant.stackexchange.com",
"https://quant.stackexchange.com/users/5456/"
] | I would absolutely use a mark-to-market value in your daily pnl for the purposes of evaluating performance (e.g. Sharpe). So, yes, that would include the value of open positions in addition to your cash balance.
If you hold something for a year, that performance was earned one day at a time, not all at once. If you only look at cash, you will have a large cash flow when you exit a position, and that will overstate the volatility of your returns. The difference in standard deviation between [0,0,0,0,0,0,0,0,99] vs [11,11,11,11,11,11,11,11,11] is significant, even though they total the same.
The effect of interest might be relevant (as BlueTrin as suggested), but is secondary to the importance of using mark-to-market. | For a single day as long as $K(t+1)$ includes the intraday cash flows it is the same, however if you do not simulate your cash balance interest rate you forget that your cash get compounded over time, which is slightly incorrect.
This is why someone suggested you simulate your cash balance. This is more correct as well if you are not always 100% invested or if you have access to leverage as you get interest or get charged for being in credit/debit. |
2,097 | Now we're into week 6 of the "Top Question" of Super User in the [Super User blog](http://superuser.blogoverflow.com). Please post and vote for your favorite question for this week.
Please post any question that you feel is of worth and the reason why. Try not to promote your own questions or answers for publicity sake. We are looking for questions that are of similar par to those selected in the [Super User Contest](https://meta.superuser.com/search?q=super+user+contest). If you like a posted question then vote it up. Each we week we are going to try to post about the question and it's contents. | 2011/02/14 | [
"https://meta.superuser.com/questions/2097",
"https://meta.superuser.com",
"https://meta.superuser.com/users/47225/"
] | Not to blow my own trumpet but the [HP CPU Assassin](https://superuser.com/questions/240794/why-does-wmi-provider-host-wmiprvse-exe-keep-spiking-my-cpu) (thanks @nhinkle for the title) and [Browser Addon to filter Google search results](https://superuser.com/questions/245959/is-there-a-browser-addon-to-filter-google-search-results) are both good. | I motion to include [Is there any product to prevent a broken screen's pieces from falling from it?](https://superuser.com/questions/246365/is-there-any-product-to-prevent-a-broken-screens-pieces-from-falling-from-it) because of the ridiculousness of the answer. |
345,310 | Clustering algorithm defines a particular distance (correlation or euclidean) and a linkage (which, strangely some books call distance - single, complete, average or centroid). Conceptually, correlation or euclidean distance measure distance between two points (but not clusters, perhaps); linkages measure distance between one cluster and other clusters (or points).
So, when the algorithm is applied, how does it matter what distance (correlation/euclidean) I choose, if the dissimilarity and subsequent grouping done only on the basis of linkages?
I know the distance choice matters because it gave me a different answer and dendograms for both measures.
Please help, thanks! | 2018/05/09 | [
"https://stats.stackexchange.com/questions/345310",
"https://stats.stackexchange.com",
"https://stats.stackexchange.com/users/185332/"
] | The linkage defines how the distances are *aggregated*.
Without the underlying distance, there would be nothing to aggregate. Nothing to take the minimum/maximum/average of. **The definitions of linkages *require* a distance**. | The linkage criterion is a function of the distance metric that you choose.
For instance, let's consider the average-linkage criterion. Here's the formula:
[](https://i.stack.imgur.com/WpPwh.png)
Notice that the `d` in the above formula is the chosen distance metric.
If you had chosen Euclidean distance, then that could provide a different value for the linkage function as compared to say, the Mahalanobis distance. |
126,796 | I have collected SVG icons from different sources. Some use thick paths and shapes. Others use thin ones.
Is there a way to change the thickness of paths and shapes in an SVG without having to adjust all the points in the object?
[](https://i.stack.imgur.com/1JaIo.png) | 2019/07/19 | [
"https://graphicdesign.stackexchange.com/questions/126796",
"https://graphicdesign.stackexchange.com",
"https://graphicdesign.stackexchange.com/users/65558/"
] | It would depend on how the graphics were constructed.
If it's made of simple strokes, then you could just apply a thinner stroke.
If the strokes have been converted to outlines, all bets are probably off. In this case it would be easier to redraw them as strokes, and apply a thinner stroke.
I don't use Sketch, but the example below was done in Inkscape. I redrew the shapes with the Bézier/Pen tool, and changed the stroke size. It should also be possible in Sketch
[](https://i.stack.imgur.com/0BlpD.png) | Sketch doesn't have strokes. To make a line icon in Sketch you need to make a smaller version of a path (shape) and change the fill color.
To fix the problem, I had to ungroup the paths, remove the fill color, add a border and increase the thickness.
[](https://i.stack.imgur.com/0Ow7t.png) |
113,384 | Any idea what the default login is? None of my oracle accounts are working. | 2010/02/25 | [
"https://superuser.com/questions/113384",
"https://superuser.com",
"https://superuser.com/users/10151/"
] | Hey, I got it, you have to log in as SYS as sysdba. I swear I had tried that, but it works now. | I had the same problem and struggled quite a bit searching for any document regarding this.
Actually I got it worked using the **SYSMAN** username, providing the same password which was asked while installing the 11g R2, which is asked right after when it asks for the email and all for updates regarding product. And logged in using the above credentials as **Normal** type.
The other usernames such as **SYS**, **SYSTEM** etc didn't worked for me as both Normal or SYSDBA type. |
61,845 | I have a rooted Android, and I want to disable (not read/write/execute) permissions to an app (for example, I don't want it accessing the camera or the phone).
Where does Android keep those permissions? Is it in a database somewhere? | 2014/01/24 | [
"https://android.stackexchange.com/questions/61845",
"https://android.stackexchange.com",
"https://android.stackexchange.com/users/50388/"
] | I've run out of space in comments so let's look at some options:
1) Go to Settings > Apps then go to Google Play Store and 'Uninstall Updates'. Then let the Play Store automatically update. Try downloading another keyboard.
2) If you have error 110 it MAY be hardware related. [Thread on similar issue](http://androidforums.com/samsung-galaxy-tab/795688-unknown-error-code-during-application-install-110-a.html)
You may need to contact the seller or Samsung on this issue.
3) If you have error 101 then perhaps [Google Play Services is to blame](https://play.google.com/store/apps/details?id=com.google.android.gms&hl=en_GB) try installing this from the link provided, reboot and try installing another keyboard.
4) Go to Settings > Apps and see if 'Samsung Keyboard' or similar is there at all, it MAY be disabled or something simple like that! (It will say 'disabled' beside it) You can go into it an click enable in this case.
5) See if you can download any apps at all from the Play Store. Pick something popular like "Facebook" or something from a reliable source. If this also fails there is somthing more fundemental wrong here.
6) If you are a bit more adventurous you could pop to XDA Devlopers and ask someone to post the APK (android application package, basically the app to be installed) for your keyboard and see if you can install it. This is a bit more advanced and I think best left til last resort for now. I'll talk you through it if you think it is a valid option. "Side Loading" is the term to look up! | The user manual advised to restart the tablet it becomes slow or unresponsive and my keyboard reappeared. The slide out icon / split screen function had stopped working on mine as well, that has started again too. |
105,334 | [The Mirror Universe](https://memory-alpha.fandom.com/wiki/Mirror_universe) is depicted in no fewer than [eight Star Trek episodes](https://memory-alpha.fandom.com/wiki/Mirror_universe#Appendices).
Yet I believe it was reached many different ways, intentional and not.
How many ways are there to travel between the Prime Universe and the Mirror Universe?
===================================================================================== | 2015/10/17 | [
"https://scifi.stackexchange.com/questions/105334",
"https://scifi.stackexchange.com",
"https://scifi.stackexchange.com/users/3823/"
] | Detonation of a tricobalt warhead inside the gravity well of a dead star
------------------------------------------------------------------------
In the ENT episode [*In a Mirror, Darkly*](https://memory-alpha.fandom.com/wiki/In_a_Mirror,_Darkly_(episode)):
>
> In the mirror universe, 2155, the Tholians detonated a tricobalt warhead inside the gravity well of a dead star, creating an interphasic rift to the year 2268 of the prime universe.
>
>
>
An ion storm during transporter operation
-----------------------------------------
In the TOS episode [*Mirror, Mirror*](https://memory-alpha.fandom.com/wiki/Mirror,_Mirror_(episode)):
>
> First they were in their own transporter chamber then they faded and upon finally materializing they had appeared wherever they were. Scotty said that the transporter lock could have been affected by the ion storm and they just materialized somewhere else. Kirk then realizes what has happened. They've somehow entered a parallel universe, where everything's duplicated... or, almost duplicated. Everyone contemplates the thought that they all likely have counterparts in the universe that they exchanged places with during transport. That there were similar storms on both universes disrupted both sets of transporter circuits.
>
>
>
Failed collapse of warp field during wormhole transport
-------------------------------------------------------
In the DS9 episode [*Crossover*](https://memory-alpha.fandom.com/wiki/Crossover_(episode)):
>
> As their runabout drops out of warp, the warp field does not collapse properly and they are engulfed in a white flash upon entering the wormhole. When they exit the Bajoran wormhole in the Alpha Quadrant, they are shocked to see the station is gone, instead orbiting Bajor much as it did during the occupation.
>
>
>
Unknown programming of a multidimensional transporter
-----------------------------------------------------
In the DS9 episode [*Shattered Mirror*](https://memory-alpha.fandom.com/wiki/Shattered_Mirror_(episode)):
>
> When he returns, he discovers they have left the station, leaving behind a multidimensional transporter device. Sisko tries to follow this trail, accompanied by Major Kira and Chief O'Brien, only to discover the device was programmed to transport him to the mirror universe alone.
>
>
>
And in the DS9 episode [*The Emperor's New Cloak*](https://memory-alpha.fandom.com/wiki/The_Emperor%27s_New_Cloak_(episode)):
>
> They bring the cloaking device to Ezri in cargo bay 14, where she has apparently set up the interdimensional transporter needed to travel to the alternate universe. As she gets it ready, Rom observes the striking resemblance to the Ezri he knows. However, before she leaves, Quark decides that he and Rom need to go with her to ensure they get Zek back. Ezri does not think doing so is a good idea, but as Martok angrily enters the cargo bay and comes after them, the mirror universe suddenly looks a lot more appealing. The three of them transport across with the cloaking device.
>
>
> | It's worth mentioning that in the (ambiguously) canon game Star Trek Online, there's a "Mirror Universe Invasion" event happening right now. The Terran ships are entering the Prime Universe through artificial "rifts", with no real explanation as of now. |
32,973 | When playing Head To Head Online Seasons in FIFA 12, on the squad selection screen some of the players have one or more symbols next to their name. What do these symbols signify? | 2011/10/21 | [
"https://gaming.stackexchange.com/questions/32973",
"https://gaming.stackexchange.com",
"https://gaming.stackexchange.com/users/1561/"
] | The symbols you are referring to depict a player's so called ***specialities***.
Specialities are divided into silver and gold ones, where gold ones are showing that the player is a really great talent. They are awarded for high stats in certain areas, for example the *Speedster* speciality is awarded to players with high acceleration and sprint speed (>= 90 I believe).
You can view the specialities for a specific player in the Team Management view:
*Main Menu -> Customize Fifa -> Edit Teams -> Team Management -> Select a team -> Squad -> Select a player with a speciality -> press `LT`*
Notice that only the best 3 specialities are shown in the team overview, in the below example you can see that C. Ronaldo actually has more than those 3:
---
The following list of specialities is assembled by hand, so it might be incomplete or contain errors.
### Silver:
**Clinical Finisher**
Clinical Finishers have the technique required to be deadly goal scorers from anywhere within 25 yards. They have an eye for the goal, and will make you pay for your mistakes.
**Crosser:**
This player is excellent at swinging the ball in from the wing. They are accurate, serve the ball with pace, and can bend it around defenders into dangerous areas.
**Distance Shooter**
This player not only has a powerful shot, they are accurate from distance. If you get the ball in open space, don't be afraid to take a pop at goal.
**Dribbler**
This player has excellent ball control and is great at getting around defenders. He will also likely have a few tricks up his sleeve and will use them to beat his opponents.
**FK Specialist**
FK specialists have spent countless hours on the training ground taking free kicks. Some will be able to curl the ball around the wall, some will get it up over the wall and back down.
**Playmaker**
This player has exceptional ability to distribute balls to his teammates. On the ground or through the air, he is the guy you want to play through to create chances.
**Poacher**
The Poacher excels in Finishing inside the penalty area both with their feet and with their head. They have the ability to turn half chances into goals.
**Speedster**
A speedster is a player who can not only get off the mark quickly, but also has a very high top speed.
**Strength**
Players with the Strength speciality are forces to be reckoned with. They are difficult to push off the ball and use their size and strength to their advantage when defending.
**Tackling**
Tacklers have mastered the art of dispossesion. They react quickly to the situation to read the dribbler and are able to break up more plays than the average defender.
**Tactician**
This player is fantastic at reading the game defensively. He will excel at reading the trajectory of passes, and will react faster off the mark to intercept passes.
### Gold:
**Complete Defender**
This player is multitalented and excels in a number of key areas of defending, making him the complete package in terms of defending.
**Complete Forward**
This player is multitalented and excels in a number of key attacking areas, making him the complete Forward package. | In fifa-11
>
> The way the personality of each player is reflected in how they play is the most impressive thing, however. On the squad selection screen players have symbols by their names signifying their special attributes; Torres, for example, is both a Speedster and an Acrobat, meaning he's more likely to perform the spectacular in the box and can sprint with gusto. Gerrard, meanwhile, is a Crosser, Playmaker and Engine among other things, a complete midfielder who can perform at his best for almost the entire 90 minutes. Learn a team well enough and you'll soon know who can do what and tailor your play accordingly. It's all the more gratifying when you know the team from what's just happened on Saturday afternoon.
>
>
>
[Quoted From Here](http://ps3.ign.com/articles/111/1119252p1.html). I believe it's the same way in FIFA '12. |
302,468 | I was wondering if anyone could shed some more definite light on the origin of the phrase 'Dutch Courage.'
I have found two, almost certainly apocryphal, origins:
>
> 1: From the [Thirty Years War](https://en.wikipedia.org/wiki/Thirty_Years%27_War) in the 17th Century, where British soldiers drank a Dutch Gin for it's warming/calming effects.[2](https://en.wikipedia.org/wiki/Dutch_courage)
>
>
>
and
>
> 2: Deriving "from the disparaging idea that Johnny Foreigner, whether sailing up the Medway or facing down the locals in the East Indies, needed a few drinks before a fight."[3](http://www.historyextra.com/qa/dutch-courage)
>
>
>
However, the phrase only seems to begin appearing in print from the [mid- to late-19th Century](http://www.oed.com/view/Entry/43146?rskey=yjdNag&result=1&isAdvanced=false#eid8120844) - some 200 years after its supposed coinage. Which makes me suspect there is another story behind this.
Unfortunately, as with many popular folk etymologies they swamp any other potential sources, so I look to EL&U for some help. | 2016/01/26 | [
"https://english.stackexchange.com/questions/302468",
"https://english.stackexchange.com",
"https://english.stackexchange.com/users/119050/"
] | ***[Dutch courage](http://dictionary.reference.com/browse/dutch-courage):***
>
> * False courage acquired by drinking liquor, as in He had a quick drink to give him Dutch courage. ***This idiom alludes to the reputed heavy drinking of the Dutch, and was first referred to in Edmund Waller's Instructions to a Painter (1665):***
>
>
> + “***The Dutch their wine, and all their brandy lose, Disarm'd of that from which their courage grows.”***.
>
>
>
(The American Heritage® Idioms Dictionary)
The following ***[source](http://www.historyextra.com/qa/dutch-courage)*** cites two possible origins, but the "gin" related one appear to support the above assumption:
>
> * In many ways, the Dutch used to be Britain’s closest neighbours. From the rise of the United Provinces during the reign of Elizabeth I until the eclipse of the Netherlands as a major power in the Napoleonic wars, they were sometimes enemies but more usually co-religionist allies, important trading partners and occasional colonial rivals. And, of course a Dutchman, William, became king of England in 1689.
> * These connections are evident in our language: slang dictionaries are full of expressions such as ‘going Dutch’, ‘Dutch auction’ and ‘Dutch uncle’.
>
>
> ***‘Dutch courage’ has two possible origins:***
>
>
> * ***The first derives from the disparaging idea that Johnny Foreigner, whether sailing up the Medway or facing down the locals in the East Indies,*** needed a few drinks before a fight.
> * ***The second theory relates more directly to the use of a specific drink – gin – to bolster one’s courage.***
> * ***Gin in its modern form was reputedly invented by the Dutch physician Franz de le Boë (Franciscus Sylvius) in the 17th century.*** British troops fighting Louis XIV alongside their allies in the Low Countries appreciated the calming effects of Jenever (Dutch gin) before heading into battle. Cheap gin was widely available in London by the early 18th century.
> * Whether or not it specifically referred to gin, ‘Dutch courage’ as an English colloquialism tended to mean using spirits, not just beer, to stiffen resolve.
>
>
>
(www.historyextra.com) | On a tour in London 2012 our guide stated that Durch Courage came about in the rat plague when only Dutch vessels still traded and berthed in the Thames.
The British Government issued barrell of rum to each Dutch ship that continued to trade, for their Dutch Courage. |
302,468 | I was wondering if anyone could shed some more definite light on the origin of the phrase 'Dutch Courage.'
I have found two, almost certainly apocryphal, origins:
>
> 1: From the [Thirty Years War](https://en.wikipedia.org/wiki/Thirty_Years%27_War) in the 17th Century, where British soldiers drank a Dutch Gin for it's warming/calming effects.[2](https://en.wikipedia.org/wiki/Dutch_courage)
>
>
>
and
>
> 2: Deriving "from the disparaging idea that Johnny Foreigner, whether sailing up the Medway or facing down the locals in the East Indies, needed a few drinks before a fight."[3](http://www.historyextra.com/qa/dutch-courage)
>
>
>
However, the phrase only seems to begin appearing in print from the [mid- to late-19th Century](http://www.oed.com/view/Entry/43146?rskey=yjdNag&result=1&isAdvanced=false#eid8120844) - some 200 years after its supposed coinage. Which makes me suspect there is another story behind this.
Unfortunately, as with many popular folk etymologies they swamp any other potential sources, so I look to EL&U for some help. | 2016/01/26 | [
"https://english.stackexchange.com/questions/302468",
"https://english.stackexchange.com",
"https://english.stackexchange.com/users/119050/"
] | The answer posted by user66974 correctly notes that an allusion to Dutch courage as flowing from a bottle of spirits appears in the course of a lengthy poem by Edmund Waller, "[Instructions to a Painter for the Drawing of a Picture of the State and Posture of the English Forces at Sea, Under the Command of His Royal Highness in the Conclusion of the Year 1664](https://quod.lib.umich.edu/e/eebo/A67334.0001.001/1:1?ALLSELECTED=1;c=eebo;c=eebo2;g=eebogroup;rgn=div1;singlegenre=All;sort=occur;subview=detail;type=simple;view=fulltext;xc=1;q1=brandy+lose)" (1665), which reads, in part, as follows:
>
> Our first success in War, make Bacchus crown, / And half the Vintage of the year our own; / **The Dutch their Wine, and all their Brandy lose,** / **Dis-arm'd of that from which their Courage grows.** / While the glad English to relieve their Toyl, / In Healths to their great Leader drink the spoyl.
>
>
>
The description here seems to involve the capture of Dutch ships loaded with wine and brandy—but the suggestion, unmistakably, is that the Dutch sailors relied on drinking alcohol to bolster their bravery.
Nevertheless, the earliest Google Books match for the exact phrase "Dutch courage" in connection with imbibing alcohol is from more than a century later. From "[Interesting Particulars of the Late Engagement Between Admirals Hyde Parker and Zoutman](https://books.google.com/books?id=icVJAAAAMAAJ&pg=PA517&dq=%22dutch+courage%22&hl=en&newbks=1&newbks_redir=0&sa=X&ved=2ahUKEwiqvbPolfb1AhU9JUQIHZKuBSMQ6AF6BAgHEAI#v=onepage&q=%22dutch%20courage%22&f=false)" in *The Political Magazine and Parliamentary, Naval, Military, and Literary Journal* (September 1781):
>
> In another part of the same letter [from Captain Decker of the *Bellona* to the *Amsterdam Gazette*, published on August 17, 1781], the writer in the true stile of rhodomontade says, "our Captain showed himself a hero and a lion in the midst of the fire ; and the crew were so full of zeal, that it was with great difficulty they were kept from firing, in their fury, into our own vessels. If this story is true, it is very probable the Dutch sailors were drunk. **Dutch courage** has been long proverbial.
>
>
>
The word *rhodomontade* derives from the character Rodomonte in Matteo Boiardo's *Orlando Innamorato* (1612) and means (according *Merriam-Webster's Eleventh Collegiate Dictionary* (2003) "a bragging speech" or "vain boasting or bluster: rant." So, on the one hand, we have a surprisingly late first confirmed print occurrence of the expression "Dutch courage" in the sense of "alcohol-fueled bravery" and, on the other, an assertion in that very same occurrence that the expression "has been long proverbial" in English.
Instances of "Dutch courage" in the relevant sense become much more frequent from the early 1800s onward.
From Thomas Trotter, [*An Essay, Medical, Philosophical, and Chemical, on Drunkenness and Its Effects on the Human Body*](https://books.google.com/books?id=_ZVkAAAAcAAJ&pg=PA143&dq=%22dutch+courage%22&hl=en&newbks=1&newbks_redir=0&sa=X&ved=2ahUKEwiqvbPolfb1AhU9JUQIHZKuBSMQ6AF6BAgGEAI#v=onepage&q=%22dutch%20courage%22&f=false), second edition (1804):
>
> It is well known that the modern armies of France are much addicted to drinking spirits; and many of their greatest victories are said to have been obtained under the fury inspired by dram-drinking; the spirits being supplied to the soldiers while engaged, by women who attended them for that service. This is a species of prowess which our tars call ***Dutch courage***; and which, I hope, will never be resorted to by Britons in the present contest with France.
>
>
>
From Diedrich Knickerbocker [Washington Irving], [*A History of New York*](https://books.google.com/books?id=AvwXAAAAYAAJ&pg=PA150&dq=%22dutch+courage%22&hl=en&newbks=1&newbks_redir=0&sa=X&ved=2ahUKEwiqvbPolfb1AhU9JUQIHZKuBSMQ6AF6BAgJEAI#v=onepage&q=%22dutch%20courage%22&f=false) (1809):
>
> The bewildered Swede [Risingh] staggered with the blow [from Peter Stuyvesant's wooden leg], and in the mean time the wary Peter, espying a pocket pistol lying hard by (which had dropped from the wallet of his faithful squire and trumpeter Van Corlear during his furious encounter with the drummer) discharged it full at the head of the reeling Risingh—Let not my reader mistake—it was not a murderous weapon loaded with powder and ball, but a little sturdy stone pottle, charged to the muzzle with a double dram of true **dutch courage**, which the knowing Van Corlear always cried about with him by way of replenishing his valour.
>
>
>
And from "[Supplemental Journal](https://books.google.com/books?id=pzhOAAAAMAAJ&pg=PA1593&dq=%22dutch+courage%22&hl=en&newbks=1&newbks_redir=0&sa=X&ved=2ahUKEwiihbqphff1AhWAKEQIHdXjBUg4FBDoAXoECAkQAg#v=onepage&q=%22dutch%20courage%22&f=false)" (April 1, 1812) in *The Debates and Proceedings in the Congress of the United States*, volume 2 (1853):
>
> Mr. RANDOLPH then said, that the step we are about taking is too high a price to pay for the consistency of gentlemen who think they have gone too far to recede; it is too expensive to bolster them up in this way. He asked what will be the situation of this people in sixty days? Put your note into the bank, and see how soon it will be out. What will be the sitution of this unhappy, misguided country? What would it have been for sixty, one hundred, or three hundred and sixty-five days past? He had hoped not to have seen the old story of the dog worrying the cat, &c., realized. Are the majority, in consequence of having been goaded by the presses, to plunge the people into war by bringing them first to the whipping post and then by exciting their spirit? He would assure the House the spirit of the people is not up to it at this time; if so there would be no necessity of those provocations to excite this false spirit—this kind of **Dutch courage**. If you mean war, if the spirit of the country is up to it, why have you been spending five months in idle debate?
>
>
>
Here, "Dutch courage" is used figuratively for "false bravado," with little or no literal connection to alcohol consumption.
And from David Porter, [*Journal of a Cruise Made to the Pacific Ocean in the United States Frigate Essex*](https://books.google.com/books?id=D18PAQAAMAAJ&pg=PA183&dq=%22dutch+courage%22&hl=en&newbks=1&newbks_redir=0&sa=X&ved=2ahUKEwj--uGi_fb1AhVQH0QIHXl8AKs4ChDoAXoECAUQAg#v=onepage&q=%22dutch%20courage%22&f=false) (1815):
>
> This vessel proved to be the British letter of marque ship Greenwich, of ten guns, a prime sailer, employed in the whale fishery. Her captain had taken in a good stock of **Dutch courage**, and, from the preparations that were made on board his vessel, there could be no doubt of his intentions to have fired into us, had he not been intimidated by the shot e fired between his masts.
>
>
>
The captain of the Greenwich (John Shuttleworth) is later described as "so much intoxicated, and his language so insulting, that it was with difficulty I [Captain Porter] could refrain from turning him out of my cabin"—so it is clear that Captain Shuttleworth "had taken in a good stock of Dutch courage" internally—and not merely as a provision on board his vessel.
---
***Conclusions***
It is by no means implausible that "Dutch courage" as a fixed phrase may date to the seventeenth century, given the claim in the earliest confirmed match that I could find for it in the relevant sense (from 1781) that as of that date it had already long been proverbial. However, the existence of a popular opinion among British sailors that Dutch seamen took their courage from a bottle, even to the extent of its being viewed as "proverbial," does not require the existence of the exact phrase "Dutch courage" for alcohol-fueled fortitude.
On the basis of the print record that I have seen, it seems quite possible that the precise figurative expression "Dutch courage" arose in the second half of the eighteenth century and that it did not become widespread among English speakers in Britain and North America until the early nineteenth century. | On a tour in London 2012 our guide stated that Durch Courage came about in the rat plague when only Dutch vessels still traded and berthed in the Thames.
The British Government issued barrell of rum to each Dutch ship that continued to trade, for their Dutch Courage. |
1,969,429 | I'm using a button in a template field of gridview. On button click I want to redirect to another page but it throws an exception:
>
> Invalid postback or callback argument. Event validation is enabled using in configuration or <%@ Page EnableEventValidation="true" %> in a page. For security purposes, this feature verifies that arguments to postback or callback events originate from the server control that originally rendered them. If the data is valid and expected, use the ClientScriptManager.RegisterForEventValidation method in order to register the postback or callback data for validation.
>
>
>
What can I do to resolve this problem? | 2009/12/28 | [
"https://Stackoverflow.com/questions/1969429",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/239574/"
] | I have faced this error on a Windows 64 bit. I have uninstalled my python 3.4.1 and I have installed: python-3.4.1.amd64.msi then pygame-1.9.2a0.win-amd64-py3.4.exe from link mentioned above. And it worked. | This actually happened to my installation as well. I have Python 2.6.6 installed, but the installation did not include Pygame. I downloaded Pygame 1.9.1 with Python 2.6, and identified where the directory was located, the installation seemed to work. However, from the IDLE, I entered import pygame, and received the very error originally posted. |
1,969,429 | I'm using a button in a template field of gridview. On button click I want to redirect to another page but it throws an exception:
>
> Invalid postback or callback argument. Event validation is enabled using in configuration or <%@ Page EnableEventValidation="true" %> in a page. For security purposes, this feature verifies that arguments to postback or callback events originate from the server control that originally rendered them. If the data is valid and expected, use the ClientScriptManager.RegisterForEventValidation method in order to register the postback or callback data for validation.
>
>
>
What can I do to resolve this problem? | 2009/12/28 | [
"https://Stackoverflow.com/questions/1969429",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/239574/"
] | I have faced this error on a Windows 64 bit. I have uninstalled my python 3.4.1 and I have installed: python-3.4.1.amd64.msi then pygame-1.9.2a0.win-amd64-py3.4.exe from link mentioned above. And it worked. | I had this error and after much digging discovered that the version of python interpreter MUST match the version of pygame installed.
If you have an erroneous combination, your best bet is to uninstall what you have via Start -> Control Panel -> Uninstall Programs.
A combination that works (Install in this order) -
Python 3.2.5 - Msi download this file for Windows Vista 32-bit-
www.python.org/download/releases/3.2.5/ - Windows x86 MSI Installer (3.2.5) <- This link, about halfway down the page
Pygame - pygame.org/download.shtml -
pygame-1.9.2a0.win32-py3.2.msi <- This download link, bottom of the top list on the page.
Now you should be able to open IDLE (The default development environment) by finding the python folder from your start menu. Once it's open, type 'import pygame'. Hopefully, you'll get no errors and pygame was imported properly. I wish you luck with your programming endeavours.
If you're dissatified with the IDLE environment and want to use another, I personally use the LiClipse IDE. I have no rep, but a google search should turn that one out ;) |
1,969,429 | I'm using a button in a template field of gridview. On button click I want to redirect to another page but it throws an exception:
>
> Invalid postback or callback argument. Event validation is enabled using in configuration or <%@ Page EnableEventValidation="true" %> in a page. For security purposes, this feature verifies that arguments to postback or callback events originate from the server control that originally rendered them. If the data is valid and expected, use the ClientScriptManager.RegisterForEventValidation method in order to register the postback or callback data for validation.
>
>
>
What can I do to resolve this problem? | 2009/12/28 | [
"https://Stackoverflow.com/questions/1969429",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/239574/"
] | This actually happened to my installation as well. I have Python 2.6.6 installed, but the installation did not include Pygame. I downloaded Pygame 1.9.1 with Python 2.6, and identified where the directory was located, the installation seemed to work. However, from the IDLE, I entered import pygame, and received the very error originally posted. | To check exactly which DLL's are missing use the CMD like python console. It will show a pop-up message indicating the missing DLL. Pygame works for me. |
1,969,429 | I'm using a button in a template field of gridview. On button click I want to redirect to another page but it throws an exception:
>
> Invalid postback or callback argument. Event validation is enabled using in configuration or <%@ Page EnableEventValidation="true" %> in a page. For security purposes, this feature verifies that arguments to postback or callback events originate from the server control that originally rendered them. If the data is valid and expected, use the ClientScriptManager.RegisterForEventValidation method in order to register the postback or callback data for validation.
>
>
>
What can I do to resolve this problem? | 2009/12/28 | [
"https://Stackoverflow.com/questions/1969429",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/239574/"
] | If you are running a 64 bit version of windows, with a 64 bit python, the default installers on the Pygame site don't seem to work.
The pygame website led me there: There are some pre release binaries for 64bit windows, and for python 2.7 at <http://www.lfd.uci.edu/~gohlke/pythonlibs/#pygame> | This actually happened to my installation as well. I have Python 2.6.6 installed, but the installation did not include Pygame. I downloaded Pygame 1.9.1 with Python 2.6, and identified where the directory was located, the installation seemed to work. However, from the IDLE, I entered import pygame, and received the very error originally posted. |
1,969,429 | I'm using a button in a template field of gridview. On button click I want to redirect to another page but it throws an exception:
>
> Invalid postback or callback argument. Event validation is enabled using in configuration or <%@ Page EnableEventValidation="true" %> in a page. For security purposes, this feature verifies that arguments to postback or callback events originate from the server control that originally rendered them. If the data is valid and expected, use the ClientScriptManager.RegisterForEventValidation method in order to register the postback or callback data for validation.
>
>
>
What can I do to resolve this problem? | 2009/12/28 | [
"https://Stackoverflow.com/questions/1969429",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/239574/"
] | I have faced this error on a Windows 64 bit. I have uninstalled my python 3.4.1 and I have installed: python-3.4.1.amd64.msi then pygame-1.9.2a0.win-amd64-py3.4.exe from link mentioned above. And it worked. | I had the exact same error however i ran a small program i found the used pygame without the IDLE(by saving the code and then just double clicking on the .py file) and it worked 100% fine. |
1,969,429 | I'm using a button in a template field of gridview. On button click I want to redirect to another page but it throws an exception:
>
> Invalid postback or callback argument. Event validation is enabled using in configuration or <%@ Page EnableEventValidation="true" %> in a page. For security purposes, this feature verifies that arguments to postback or callback events originate from the server control that originally rendered them. If the data is valid and expected, use the ClientScriptManager.RegisterForEventValidation method in order to register the postback or callback data for validation.
>
>
>
What can I do to resolve this problem? | 2009/12/28 | [
"https://Stackoverflow.com/questions/1969429",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/239574/"
] | Are you sure you have got pygame for Python 2.6? The version for 2.5 wont work and produce this error msg, because the pyd file wont find the python 2.5 dll. | If you are running a 64 bit version of windows, with a 64 bit python, the default installers on the Pygame site don't seem to work.
The pygame website led me there: There are some pre release binaries for 64bit windows, and for python 2.7 at <http://www.lfd.uci.edu/~gohlke/pythonlibs/#pygame> |
1,969,429 | I'm using a button in a template field of gridview. On button click I want to redirect to another page but it throws an exception:
>
> Invalid postback or callback argument. Event validation is enabled using in configuration or <%@ Page EnableEventValidation="true" %> in a page. For security purposes, this feature verifies that arguments to postback or callback events originate from the server control that originally rendered them. If the data is valid and expected, use the ClientScriptManager.RegisterForEventValidation method in order to register the postback or callback data for validation.
>
>
>
What can I do to resolve this problem? | 2009/12/28 | [
"https://Stackoverflow.com/questions/1969429",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/239574/"
] | If you are running a 64 bit version of windows, with a 64 bit python, the default installers on the Pygame site don't seem to work.
The pygame website led me there: There are some pre release binaries for 64bit windows, and for python 2.7 at <http://www.lfd.uci.edu/~gohlke/pythonlibs/#pygame> | To check exactly which DLL's are missing use the CMD like python console. It will show a pop-up message indicating the missing DLL. Pygame works for me. |
1,969,429 | I'm using a button in a template field of gridview. On button click I want to redirect to another page but it throws an exception:
>
> Invalid postback or callback argument. Event validation is enabled using in configuration or <%@ Page EnableEventValidation="true" %> in a page. For security purposes, this feature verifies that arguments to postback or callback events originate from the server control that originally rendered them. If the data is valid and expected, use the ClientScriptManager.RegisterForEventValidation method in order to register the postback or callback data for validation.
>
>
>
What can I do to resolve this problem? | 2009/12/28 | [
"https://Stackoverflow.com/questions/1969429",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/239574/"
] | This actually happened to my installation as well. I have Python 2.6.6 installed, but the installation did not include Pygame. I downloaded Pygame 1.9.1 with Python 2.6, and identified where the directory was located, the installation seemed to work. However, from the IDLE, I entered import pygame, and received the very error originally posted. | I had this error and after much digging discovered that the version of python interpreter MUST match the version of pygame installed.
If you have an erroneous combination, your best bet is to uninstall what you have via Start -> Control Panel -> Uninstall Programs.
A combination that works (Install in this order) -
Python 3.2.5 - Msi download this file for Windows Vista 32-bit-
www.python.org/download/releases/3.2.5/ - Windows x86 MSI Installer (3.2.5) <- This link, about halfway down the page
Pygame - pygame.org/download.shtml -
pygame-1.9.2a0.win32-py3.2.msi <- This download link, bottom of the top list on the page.
Now you should be able to open IDLE (The default development environment) by finding the python folder from your start menu. Once it's open, type 'import pygame'. Hopefully, you'll get no errors and pygame was imported properly. I wish you luck with your programming endeavours.
If you're dissatified with the IDLE environment and want to use another, I personally use the LiClipse IDE. I have no rep, but a google search should turn that one out ;) |
1,969,429 | I'm using a button in a template field of gridview. On button click I want to redirect to another page but it throws an exception:
>
> Invalid postback or callback argument. Event validation is enabled using in configuration or <%@ Page EnableEventValidation="true" %> in a page. For security purposes, this feature verifies that arguments to postback or callback events originate from the server control that originally rendered them. If the data is valid and expected, use the ClientScriptManager.RegisterForEventValidation method in order to register the postback or callback data for validation.
>
>
>
What can I do to resolve this problem? | 2009/12/28 | [
"https://Stackoverflow.com/questions/1969429",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/239574/"
] | I have faced this error on a Windows 64 bit. I have uninstalled my python 3.4.1 and I have installed: python-3.4.1.amd64.msi then pygame-1.9.2a0.win-amd64-py3.4.exe from link mentioned above. And it worked. | To check exactly which DLL's are missing use the CMD like python console. It will show a pop-up message indicating the missing DLL. Pygame works for me. |
1,969,429 | I'm using a button in a template field of gridview. On button click I want to redirect to another page but it throws an exception:
>
> Invalid postback or callback argument. Event validation is enabled using in configuration or <%@ Page EnableEventValidation="true" %> in a page. For security purposes, this feature verifies that arguments to postback or callback events originate from the server control that originally rendered them. If the data is valid and expected, use the ClientScriptManager.RegisterForEventValidation method in order to register the postback or callback data for validation.
>
>
>
What can I do to resolve this problem? | 2009/12/28 | [
"https://Stackoverflow.com/questions/1969429",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/239574/"
] | Are you sure you have got pygame for Python 2.6? The version for 2.5 wont work and produce this error msg, because the pyd file wont find the python 2.5 dll. | I had the exact same error however i ran a small program i found the used pygame without the IDLE(by saving the code and then just double clicking on the .py file) and it worked 100% fine. |
1,180,923 | I'm quite a newbie in differential geometry. Calculus is not my cup of tea ; but I find geometrical proofs really beautiful. So I'm looking for a simple - by simple I mean with almost no calculus - proof that the shortest path between two points on a sphere is the arc of the great circle on which they lie. Any hint ?
Edit: Or at least a reference ? | 2015/03/08 | [
"https://math.stackexchange.com/questions/1180923",
"https://math.stackexchange.com",
"https://math.stackexchange.com/users/221594/"
] | You can show that great circle arcs are geodesics by parameterizing
such an arc so that it has unit speed, and then showing that the acceleration
along the arc is perpendicular to the sphere surface.
(This assumes you accept that geodesics have the characteristic
that their acceleration is perpendicular to the tangent plane of the surface at each point of the geodesic.)
Then uniqueness of the geodesic from a point in a direction shows it must be
the great circle arc.
I realize this might not be what you seek because it doesn't connect directly
to shortest paths... | By symmetry!
------------
### Simple geometric proof:
1. (*parallel symmetry*) Consider the plane that is the perpendicular bisector of the straight line segment joining the two points. All objects (i.e., the sphere and the points) are symmetric with respect to that plane, so *if the path is unique*, it *must* stay the same after it is reflected across the plane.
Why? Because otherwise it wouldn't be unique -- by reflecting the problem, we would be keeping the inputs the same, but changing the output, and hence the path wouldn't be a function of the inputs.
2. (*perpendicular symmetry*) Now consider the plane of the great circle -- that is, the plane that goes through the center of the sphere as well as the two given points. Again, the sphere and the points are reflectively symmetric with respect to this plane, so *if the path is unique*, it *must* stay the same after being reflected across this plane. (Same reason as above.)
3. (*spherical constraint*) The path must, by definition of the problem, lie *on* the sphere.
4. (*uniqueness*) The path must be unique. (This is intuitively obvious, so I won't try to prove it.)
It's easy to see that the only path that satisfies these three conditions is the one on the great circle.
Why? Because the intersection of the sphere with the two planes of symmetry clearly satisfies conditions 1-3. Furthermore, condition 4 implies that no other path can be the shortest path. Hence, the intersection of these shapes must be the shortest path itself.
---
### However...
This method only works for this problem. By contrast, calculus-based methods (see the Calculus of Variations) work for other problems that lack such symmetries, and hence you should still learn those approaches so you can solve the shortest path problem for e.g. ellipsoids. |
1,180,923 | I'm quite a newbie in differential geometry. Calculus is not my cup of tea ; but I find geometrical proofs really beautiful. So I'm looking for a simple - by simple I mean with almost no calculus - proof that the shortest path between two points on a sphere is the arc of the great circle on which they lie. Any hint ?
Edit: Or at least a reference ? | 2015/03/08 | [
"https://math.stackexchange.com/questions/1180923",
"https://math.stackexchange.com",
"https://math.stackexchange.com/users/221594/"
] | By symmetry!
------------
### Simple geometric proof:
1. (*parallel symmetry*) Consider the plane that is the perpendicular bisector of the straight line segment joining the two points. All objects (i.e., the sphere and the points) are symmetric with respect to that plane, so *if the path is unique*, it *must* stay the same after it is reflected across the plane.
Why? Because otherwise it wouldn't be unique -- by reflecting the problem, we would be keeping the inputs the same, but changing the output, and hence the path wouldn't be a function of the inputs.
2. (*perpendicular symmetry*) Now consider the plane of the great circle -- that is, the plane that goes through the center of the sphere as well as the two given points. Again, the sphere and the points are reflectively symmetric with respect to this plane, so *if the path is unique*, it *must* stay the same after being reflected across this plane. (Same reason as above.)
3. (*spherical constraint*) The path must, by definition of the problem, lie *on* the sphere.
4. (*uniqueness*) The path must be unique. (This is intuitively obvious, so I won't try to prove it.)
It's easy to see that the only path that satisfies these three conditions is the one on the great circle.
Why? Because the intersection of the sphere with the two planes of symmetry clearly satisfies conditions 1-3. Furthermore, condition 4 implies that no other path can be the shortest path. Hence, the intersection of these shapes must be the shortest path itself.
---
### However...
This method only works for this problem. By contrast, calculus-based methods (see the Calculus of Variations) work for other problems that lack such symmetries, and hence you should still learn those approaches so you can solve the shortest path problem for e.g. ellipsoids. | It's not perfect but a more rigorous version of the following should work:
Take a sphere centered at the origin and two points. Your problem space is symmetric about the origin. Your looking for the third point on the path to define a plane that will contain the shortest path between the 2 points (and hence point c cannot be point a or b or we wouldn't have a clearly defined plane). Your three points will be co-planar. Every plane cut of a sphere results in a circle. Increasing the radius of that circle reduces the distance of the three points (triangle inequality). So we're going to change the goal of our third point that defines our plane: maximize the radius of the circle between the 2 points. Maximize radius by placing third point at center (that's the cut that's going to result in the largest circle). The 2 points will define arcs of the shortest and longest path between them, just figure out which is which. |
2,122,182 | I am developing an iPhone tabbar application with 5 tabs .
I want to show only two tabs at the launch time such as one is "locate me".
When the user taps on the locate me tab another 3 tabs will be shown and can use the current location.
I want to do some thing like "urban spoon" .
I am using the interface builder for all the stuff.
If any one have any idea , suggestion , links then provide me.
Thanks
. | 2010/01/23 | [
"https://Stackoverflow.com/questions/2122182",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/95844/"
] | Can you try File->Import and then choose Existing Projects into Workspace and then select the directory with your HelloWorld project? | Looks like I had it checked not to show closed projects. |
2,122,182 | I am developing an iPhone tabbar application with 5 tabs .
I want to show only two tabs at the launch time such as one is "locate me".
When the user taps on the locate me tab another 3 tabs will be shown and can use the current location.
I want to do some thing like "urban spoon" .
I am using the interface builder for all the stuff.
If any one have any idea , suggestion , links then provide me.
Thanks
. | 2010/01/23 | [
"https://Stackoverflow.com/questions/2122182",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/95844/"
] | Can you try File->Import and then choose Existing Projects into Workspace and then select the directory with your HelloWorld project? | Eclipse will look into the .project file in your project directory and see the original project name, which may be the same as another project. This can happen if you build a new project using some old code. |
151,765 | Does Microsoft force an update down to all of its users of windows-update? Is it for legal reasons?
EDIT(aku):
Question was reformulated. if you want to know which version of Windows comes with .NET see this topic:
<https://stackoverflow.com/questions/71390/which-operating-systems-come-with-net> | 2008/09/30 | [
"https://Stackoverflow.com/questions/151765",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/3153/"
] | Yes, Windows Vista shipped with .NET Framework 3.0. I'm sure future versions of Windows will ship with whichever is the most recent version of the framework.
Scott Hanselman recently blogged about the status of .NET 3.5 on Windows Update:
<http://www.hanselman.com/blog/UpdateOnNETFramework35SP1AndWindowsUpdate.aspx> | >
> Does Microsoft force an update down to
> all of it's users of windows-update?
> Is it for legal reasons?
>
>
>
Probably it would be better to ask Microsoft.
I can't remember a case when they forcibly installed a new version of .NET. AFAIK only critical security updates are mandatory. They don't force you to install service packs, etc. But I can be wrong :) |
151,765 | Does Microsoft force an update down to all of its users of windows-update? Is it for legal reasons?
EDIT(aku):
Question was reformulated. if you want to know which version of Windows comes with .NET see this topic:
<https://stackoverflow.com/questions/71390/which-operating-systems-come-with-net> | 2008/09/30 | [
"https://Stackoverflow.com/questions/151765",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/3153/"
] | Yes, Windows Vista shipped with .NET Framework 3.0. I'm sure future versions of Windows will ship with whichever is the most recent version of the framework.
Scott Hanselman recently blogged about the status of .NET 3.5 on Windows Update:
<http://www.hanselman.com/blog/UpdateOnNETFramework35SP1AndWindowsUpdate.aspx> | Some XP OEM installations have some version of .NET installed as it is needed from some included software. Vista comes with .NET 3.0 installed. |
151,765 | Does Microsoft force an update down to all of its users of windows-update? Is it for legal reasons?
EDIT(aku):
Question was reformulated. if you want to know which version of Windows comes with .NET see this topic:
<https://stackoverflow.com/questions/71390/which-operating-systems-come-with-net> | 2008/09/30 | [
"https://Stackoverflow.com/questions/151765",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/3153/"
] | Yes, Windows Vista shipped with .NET Framework 3.0. I'm sure future versions of Windows will ship with whichever is the most recent version of the framework.
Scott Hanselman recently blogged about the status of .NET 3.5 on Windows Update:
<http://www.hanselman.com/blog/UpdateOnNETFramework35SP1AndWindowsUpdate.aspx> | Microsoft would only push down an update as part of the Windows/Microsoft update process, and even then, only if you have them set to automatically install. If you didn't have updated configured to run without asking, then you would never have to update the .NET framework, though these updates would rarely break functionality, and are highly recommended for security reasons. |
151,765 | Does Microsoft force an update down to all of its users of windows-update? Is it for legal reasons?
EDIT(aku):
Question was reformulated. if you want to know which version of Windows comes with .NET see this topic:
<https://stackoverflow.com/questions/71390/which-operating-systems-come-with-net> | 2008/09/30 | [
"https://Stackoverflow.com/questions/151765",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/3153/"
] | Yes, Windows Vista shipped with .NET Framework 3.0. I'm sure future versions of Windows will ship with whichever is the most recent version of the framework.
Scott Hanselman recently blogged about the status of .NET 3.5 on Windows Update:
<http://www.hanselman.com/blog/UpdateOnNETFramework35SP1AndWindowsUpdate.aspx> | Scott Hanselman recently blogged about the status of .NET 3.5 on Windows Update:
<http://www.hanselman.com/blog/UpdateOnNETFramework35SP1AndWindowsUpdate.aspx> |
151,765 | Does Microsoft force an update down to all of its users of windows-update? Is it for legal reasons?
EDIT(aku):
Question was reformulated. if you want to know which version of Windows comes with .NET see this topic:
<https://stackoverflow.com/questions/71390/which-operating-systems-come-with-net> | 2008/09/30 | [
"https://Stackoverflow.com/questions/151765",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/3153/"
] | >
> Does Microsoft force an update down to
> all of it's users of windows-update?
> Is it for legal reasons?
>
>
>
Probably it would be better to ask Microsoft.
I can't remember a case when they forcibly installed a new version of .NET. AFAIK only critical security updates are mandatory. They don't force you to install service packs, etc. But I can be wrong :) | Some XP OEM installations have some version of .NET installed as it is needed from some included software. Vista comes with .NET 3.0 installed. |
151,765 | Does Microsoft force an update down to all of its users of windows-update? Is it for legal reasons?
EDIT(aku):
Question was reformulated. if you want to know which version of Windows comes with .NET see this topic:
<https://stackoverflow.com/questions/71390/which-operating-systems-come-with-net> | 2008/09/30 | [
"https://Stackoverflow.com/questions/151765",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/3153/"
] | >
> Does Microsoft force an update down to
> all of it's users of windows-update?
> Is it for legal reasons?
>
>
>
Probably it would be better to ask Microsoft.
I can't remember a case when they forcibly installed a new version of .NET. AFAIK only critical security updates are mandatory. They don't force you to install service packs, etc. But I can be wrong :) | Microsoft would only push down an update as part of the Windows/Microsoft update process, and even then, only if you have them set to automatically install. If you didn't have updated configured to run without asking, then you would never have to update the .NET framework, though these updates would rarely break functionality, and are highly recommended for security reasons. |
151,765 | Does Microsoft force an update down to all of its users of windows-update? Is it for legal reasons?
EDIT(aku):
Question was reformulated. if you want to know which version of Windows comes with .NET see this topic:
<https://stackoverflow.com/questions/71390/which-operating-systems-come-with-net> | 2008/09/30 | [
"https://Stackoverflow.com/questions/151765",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/3153/"
] | >
> Does Microsoft force an update down to
> all of it's users of windows-update?
> Is it for legal reasons?
>
>
>
Probably it would be better to ask Microsoft.
I can't remember a case when they forcibly installed a new version of .NET. AFAIK only critical security updates are mandatory. They don't force you to install service packs, etc. But I can be wrong :) | Scott Hanselman recently blogged about the status of .NET 3.5 on Windows Update:
<http://www.hanselman.com/blog/UpdateOnNETFramework35SP1AndWindowsUpdate.aspx> |
98,811 | A creationist website makes this argument for the 6,000 year old earth. I'm embarrassed to say I don't know how to do the math to evaluate the claim myself. However, the time scales involved seems to lend some credence to this argument. "The Moon is slowly drifting away from the Earth. If it is getting further, at one time it was much closer. The Inverse Square Law dictates that if the Moon were half the distance from the Earth, its gravitational pull on our tides would be quadrupled. 1/3 the distance, 9 times the pull. Everything would drown twice a day. Approximately 1.2 billion years ago, the Moon would have been touching the Earth. Drowning would be the least of our concerns! - See more at: <http://www.allaboutcreation.org/how-old-is-the-earth.htm#sthash.LSHK4GQk.dpuf>" | 2014/02/12 | [
"https://physics.stackexchange.com/questions/98811",
"https://physics.stackexchange.com",
"https://physics.stackexchange.com/users/40415/"
] | [Extrapolation](https://en.wikipedia.org/wiki/Extrapolation) is as likely to produce meaningless results when done into the past as when done into the future.
The most widely accepted theory for how the Earth-Moon system was formed is the [Giant impact hypothesis](https://en.wikipedia.org/wiki/Giant_impact_hypothesis#Energetic_aftermath): around 4.5 billion years ago, the (then itself still very new) Earth was nearly destroyed by a collision with another planet roughly the size of Mars. This created a huge cloud of debris orbiting the Earth, much of which coalesced into the moon.
So the moon first formed at a certain distance from the Earth, and that distance has since then grown due to [tidal braking](https://en.wikipedia.org/wiki/Tidal_braking) (and the same effect is steadily increasing the length of the day on Earth).
An interesting detail about your quote is that their extrapolation of 1.2 billion years is much shorter than the time since the impact, but without any indication of how that number was computed, it means nothing. It is not a linear extrapolation of the current distance (384,000km) and rate of increase (3.8cm/a) because that yields over 10 billion years. But the rate of increase really cannot be meaningfully extrapolated because it depends on the magnitude of friction caused by tidal forces, and that depends on what the Earth looks like. After the impact, the Earth was probably mostly liquid for some time, which would cause much more tidal friction and thus a much more rapid increase in distance.
But the creationists are correct about one thing: Drowning would, indeed, be the least of our concerns back then! | 63,360 x 238,900 = 15,136,704,000(inch now)
(1.5inch x 4,000,500,000 = 6,000,750,000)
15,136,704,000 - 6,000,750,000 (inch then ) = 9,135,954,000 inches.
9,135,954,000/63360=144,191.19318181 (converting it back to miles)
Roughly 144,000 miles 4.5 billion years ago
But due to the tidal friction, caused by the tidal bulge, the earth loses energy and is given to the moons orbit at a slower and slower rate as time goes by so it was much less than 144,000 miles.
The rate of the moons movement (away from earth) decreases as the moons distance (away from earth) increases. |
98,811 | A creationist website makes this argument for the 6,000 year old earth. I'm embarrassed to say I don't know how to do the math to evaluate the claim myself. However, the time scales involved seems to lend some credence to this argument. "The Moon is slowly drifting away from the Earth. If it is getting further, at one time it was much closer. The Inverse Square Law dictates that if the Moon were half the distance from the Earth, its gravitational pull on our tides would be quadrupled. 1/3 the distance, 9 times the pull. Everything would drown twice a day. Approximately 1.2 billion years ago, the Moon would have been touching the Earth. Drowning would be the least of our concerns! - See more at: <http://www.allaboutcreation.org/how-old-is-the-earth.htm#sthash.LSHK4GQk.dpuf>" | 2014/02/12 | [
"https://physics.stackexchange.com/questions/98811",
"https://physics.stackexchange.com",
"https://physics.stackexchange.com/users/40415/"
] | [Extrapolation](https://en.wikipedia.org/wiki/Extrapolation) is as likely to produce meaningless results when done into the past as when done into the future.
The most widely accepted theory for how the Earth-Moon system was formed is the [Giant impact hypothesis](https://en.wikipedia.org/wiki/Giant_impact_hypothesis#Energetic_aftermath): around 4.5 billion years ago, the (then itself still very new) Earth was nearly destroyed by a collision with another planet roughly the size of Mars. This created a huge cloud of debris orbiting the Earth, much of which coalesced into the moon.
So the moon first formed at a certain distance from the Earth, and that distance has since then grown due to [tidal braking](https://en.wikipedia.org/wiki/Tidal_braking) (and the same effect is steadily increasing the length of the day on Earth).
An interesting detail about your quote is that their extrapolation of 1.2 billion years is much shorter than the time since the impact, but without any indication of how that number was computed, it means nothing. It is not a linear extrapolation of the current distance (384,000km) and rate of increase (3.8cm/a) because that yields over 10 billion years. But the rate of increase really cannot be meaningfully extrapolated because it depends on the magnitude of friction caused by tidal forces, and that depends on what the Earth looks like. After the impact, the Earth was probably mostly liquid for some time, which would cause much more tidal friction and thus a much more rapid increase in distance.
But the creationists are correct about one thing: Drowning would, indeed, be the least of our concerns back then! | I just stumbled across this more than two years after the fact. Interesting conversation.
One thing that the creationist website and the answers I've seen in this forum have failed to address, is that the increased tidal action would not be the only effect of a closer Moon. The farther back we look in time the less chance the moon would be able to escape the Earth's gravity. It should be getting closer today and yet it is moving away instead.
For the sake of argument let's assume that the aforementioned idea that the moon was caused by a collision of another Celestial body with the primordial Earth is indeed what occurred. That leaves us with a contradiction.
With an exponential increase in gravity the closer the Moon and Earth are to one another, in order to maintain the proper balance to sustain its orbit until now, the moon would also have to be going exponentially faster the further back in time. That being the case, the debris from the Collision could never have coalesced into the moon in the first place. (These same factors, also mean the death of the capture Theory.)
Assuming such exponential speeds were not present at the time of the Collision, means the debris that would have coalesced into the Moon, would need to have accelerated dramatically once it had. This again would not have happened.
Further, through observation, we know that objects in space that break apart within the gravitational field of a planet, do not coalesce back into a localized Mass. Instead, due to the influence of the nearby gravitational field, they remain a debris field because the field exerts greater influence on the individual bits of debris than they can exert on one another.
This does not even consider heat pressure; another force working against coalescence. This, among other reasons, is the same reason nebula are coming apart rather than coalescing into new stars. |
98,811 | A creationist website makes this argument for the 6,000 year old earth. I'm embarrassed to say I don't know how to do the math to evaluate the claim myself. However, the time scales involved seems to lend some credence to this argument. "The Moon is slowly drifting away from the Earth. If it is getting further, at one time it was much closer. The Inverse Square Law dictates that if the Moon were half the distance from the Earth, its gravitational pull on our tides would be quadrupled. 1/3 the distance, 9 times the pull. Everything would drown twice a day. Approximately 1.2 billion years ago, the Moon would have been touching the Earth. Drowning would be the least of our concerns! - See more at: <http://www.allaboutcreation.org/how-old-is-the-earth.htm#sthash.LSHK4GQk.dpuf>" | 2014/02/12 | [
"https://physics.stackexchange.com/questions/98811",
"https://physics.stackexchange.com",
"https://physics.stackexchange.com/users/40415/"
] | 63,360 x 238,900 = 15,136,704,000(inch now)
(1.5inch x 4,000,500,000 = 6,000,750,000)
15,136,704,000 - 6,000,750,000 (inch then ) = 9,135,954,000 inches.
9,135,954,000/63360=144,191.19318181 (converting it back to miles)
Roughly 144,000 miles 4.5 billion years ago
But due to the tidal friction, caused by the tidal bulge, the earth loses energy and is given to the moons orbit at a slower and slower rate as time goes by so it was much less than 144,000 miles.
The rate of the moons movement (away from earth) decreases as the moons distance (away from earth) increases. | I just stumbled across this more than two years after the fact. Interesting conversation.
One thing that the creationist website and the answers I've seen in this forum have failed to address, is that the increased tidal action would not be the only effect of a closer Moon. The farther back we look in time the less chance the moon would be able to escape the Earth's gravity. It should be getting closer today and yet it is moving away instead.
For the sake of argument let's assume that the aforementioned idea that the moon was caused by a collision of another Celestial body with the primordial Earth is indeed what occurred. That leaves us with a contradiction.
With an exponential increase in gravity the closer the Moon and Earth are to one another, in order to maintain the proper balance to sustain its orbit until now, the moon would also have to be going exponentially faster the further back in time. That being the case, the debris from the Collision could never have coalesced into the moon in the first place. (These same factors, also mean the death of the capture Theory.)
Assuming such exponential speeds were not present at the time of the Collision, means the debris that would have coalesced into the Moon, would need to have accelerated dramatically once it had. This again would not have happened.
Further, through observation, we know that objects in space that break apart within the gravitational field of a planet, do not coalesce back into a localized Mass. Instead, due to the influence of the nearby gravitational field, they remain a debris field because the field exerts greater influence on the individual bits of debris than they can exert on one another.
This does not even consider heat pressure; another force working against coalescence. This, among other reasons, is the same reason nebula are coming apart rather than coalescing into new stars. |
60,030 | In this case BHX-FRA return (Lufthansa) is about £140; FRA-WDH return (Air Namibia) is about £500 - and BHX-FRA-WDH return, on *exactly the same flights* is about £900.
I understand *that* this is common, and that a single BHX-FRA-WDH ticket is actually *worth more* to the holder, because:
* if your Lufthansa flight to FRA is late, a single ticket places the airlines under an obligation to look after you, but if you bought them separately, the staff at the Air Namibia counter may well be very sorry but they can't help you...
* if you buy separate tickets, *you* will have to collect your luggage at FRA and check it back into the system
So I can also understand that there is added value in the single ticket.
Questions that have not been previously clearly answered (or posed)
===================================================================
Many questions around this topic have previously been asked and answered, but the first two below have only been answered in passing, while I have not seen any clear answers to the second two.
* Who gets the extra £260?
* Do Lufthansa and Air Namibia share it out equally?
* How does an airline even know that the tickets being purchased are just one leg of a longer journey?
* Is there some way of beating the system, by having the separate tickets reunited after purchase into a single ticket, so that for example luggage can be automatically routed to its final destination when it's checked in? | 2015/12/16 | [
"https://travel.stackexchange.com/questions/60030",
"https://travel.stackexchange.com",
"https://travel.stackexchange.com/users/38118/"
] | There is no "extra money". The BHX-FRA-WDH fare is priced as a single entity and represents just one of many different fares sold for any particular flight. No single fare class represents "The Fare" for that flight, they are all calculated using formulas that are designed to: fill the plane, cover costs of operations and make a profit.
So they aren't charging you more because they provide something extra, they are charging you more because that ticket falls into a different (more expensive) fare basis. With a few exceptions, a seat in economy gets the same services irregardless of what price you paid.
jpatokal covered the basic methods of revenue distribution, but for that flight the revenue is based on what Lufthansa's and Air Namibia's prices are for that particular fare class. The fact that other lower prices are offered on the same flight does not come into play when calculating revenue distribution for that particular ticket. | TL;DR: **It's complicated.**
Here's the baseline scenario: Flights from A via B to C, operated by airlines 1 and 2. If you buy a ticket from A to B, airline 1 gets all the money; if you buy a separate ticket from B to C, airline 2 gets all the money.
To merge the two as a connecting A-B-C flight, there are three basic options:
1. [Interline](https://en.wikipedia.org/wiki/Interlining). Two airlines agree to book each other's flights, transfer bags and guarantee connections, but set their own fares and keep them for themselves. This is the case for [Lufthansa and Air Namibia](http://www.airnamibia.com/air-namibia-targets-european-market-lufthansa/), and the reason you're seeing a different price is that they've agreed on a set of fares that *only* apply when interlining.
2. [Codeshare](https://en.wikipedia.org/wiki/Codeshare_agreement). Airline 1 buys seats from airline 2 (or vice versa) at an agreed price X, sells them at price Y (which it is free to set), and earns Y-X. (Or, alternatively, just gives airline 2 a commission.)
In this case, you're effectively buying the whole ticket from airline 1, who just happen to subcontract the operation of the B-C flight to another company.
3. [Proration](http://www.iata.org/whatwedo/workgroups/Pages/proration.aspx) aka revenue sharing. Airlines 1 & 2 agree not just to interline, but to split revenue on a deeper level, setting combined fares together and splitting the booty. These formulas are obviously secret, vary from company to company and can be [horrifically complex](http://www.agifors.org/award/submissions2011/XingHu.pdf), and depend on a whole host of factors like flight length, fare class, who sold the ticket, amount of competition on that sector etc. The extreme form of this is [metal neutrality](http://www.travel-industry-dictionary.com/metal-neutral.html), where two airlines agree to sell the others' tickets *exactly* as if they were their own; effectively a merger in disguise. |
5,161,379 | Django-Social in its feature list claims that it supports associating multiple authentication providers to a single user account.
I can't seem to figure out how to use that feature.
When I try to login using a new authentication provider it automatically seems to be creating a new account for each provider.
Any ideas?
Sarvi | 2011/03/01 | [
"https://Stackoverflow.com/questions/5161379",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/463499/"
] | Take a look to [django-social-auth](http://github.com/omab/django-social-auth/), it's simpler and easier to setup than Django-Socialauth.
Multiple account association is supported but limited to logged in users to avoid the decision of which user instance must be removed. | **it supports associating multiple authentication providers to a single user account**
By looking at the code for models.py [here](https://github.com/uswaretech/Django-Socialauth/blob/master/socialauth/models.py), socialauth has a UserProfile for each provider, associating them to the User object which you use for basic authentication. So indeed, what it claims is true. |
5,161,379 | Django-Social in its feature list claims that it supports associating multiple authentication providers to a single user account.
I can't seem to figure out how to use that feature.
When I try to login using a new authentication provider it automatically seems to be creating a new account for each provider.
Any ideas?
Sarvi | 2011/03/01 | [
"https://Stackoverflow.com/questions/5161379",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/463499/"
] | Take a look to [django-social-auth](http://github.com/omab/django-social-auth/), it's simpler and easier to setup than Django-Socialauth.
Multiple account association is supported but limited to logged in users to avoid the decision of which user instance must be removed. | It can be done manually through admin once you have logged in with multiple accounts. Then the Socialauth models for the accounts can be adjusted to point at the User they are required too and multiple accounts can point to the same user.
But I have not had a good enough look to work out how to let users do this automatically for themselves. It does not work out of the box if you sign in to another account if while already signed into an existing account. |
86,221 | I have a Yongnuo 560 ii flash that I usually use to light my white backdrop for clothing shots on a model. The issue is sometimes it doesn't make the whole background white. Either blows out the side where I locate the flash or only the higher area... all depending where I put the tripod that holds it.
I was wondering if using an umbrella can help me expand the light to the whole background and also what intensity to use in the flash so I can blow out as much background as possible.
Will it help if I place the tripod further from the background so the light expands? | 2017/01/13 | [
"https://photo.stackexchange.com/questions/86221",
"https://photo.stackexchange.com",
"https://photo.stackexchange.com/users/13847/"
] | You're making this way too hard. You don't need to light the backdrop perfectly evenly. If the dimmest area of the backdrop is blown out the rest of the backdrop will be equally blown out. There is no shade of white brighter than blown out.
Here's the problem with using an umbrella to diffuse the light or moving the light further back: You're lowering the amount of the flash's output that makes it onto each square inch of the background. That's going to make the backdrop dimmer overall. This means you're *more likely* to get varying brightness levels from different parts of the backdrop.
The key to getting uniform white backgrounds isn't illuminating them evenly. It is making sure the dimmest part of the white background is lit bright enough to be pure white with the ISO and aperture you are using. (Shutter time matters also for constant lights but not for strobes since the strobe's duration is usually shorter than the camera's sync speed.)
It doesn't matter if one side of the backdrop is getting more light than the other. **You just need to expose in such a way that the dimmest part of the backdrop is completely blown out.** You'll find this easiest to do if the flash lighting the backdrop is at full power (assuming it isn't too bright as to create a lot of spill back onto your subject).
**If the dimmest part of the backdrop is pure white in your resulting photo the entire backdrop will be pure white. There's no way for the brighter parts of the backdrop to be brighter or whiter than pure white in the resulting image.**
Once you've got the exposure right for the backdrop you can then adjust the power of the other light(s) to properly expose your subject at the same ISO and aperture. | In your case it might help to change the angle of your backdrop, so that every point of it has roughly the same distance to the flash. So if your light comes from the right, move the right side of the backdrop further away from the camera.
Of course, the backdrop has to be big enough for this. Also you can only compensate for the left-right gradient in the background, top-bottom would be a bit more difficult.. |
86,221 | I have a Yongnuo 560 ii flash that I usually use to light my white backdrop for clothing shots on a model. The issue is sometimes it doesn't make the whole background white. Either blows out the side where I locate the flash or only the higher area... all depending where I put the tripod that holds it.
I was wondering if using an umbrella can help me expand the light to the whole background and also what intensity to use in the flash so I can blow out as much background as possible.
Will it help if I place the tripod further from the background so the light expands? | 2017/01/13 | [
"https://photo.stackexchange.com/questions/86221",
"https://photo.stackexchange.com",
"https://photo.stackexchange.com/users/13847/"
] | You're making this way too hard. You don't need to light the backdrop perfectly evenly. If the dimmest area of the backdrop is blown out the rest of the backdrop will be equally blown out. There is no shade of white brighter than blown out.
Here's the problem with using an umbrella to diffuse the light or moving the light further back: You're lowering the amount of the flash's output that makes it onto each square inch of the background. That's going to make the backdrop dimmer overall. This means you're *more likely* to get varying brightness levels from different parts of the backdrop.
The key to getting uniform white backgrounds isn't illuminating them evenly. It is making sure the dimmest part of the white background is lit bright enough to be pure white with the ISO and aperture you are using. (Shutter time matters also for constant lights but not for strobes since the strobe's duration is usually shorter than the camera's sync speed.)
It doesn't matter if one side of the backdrop is getting more light than the other. **You just need to expose in such a way that the dimmest part of the backdrop is completely blown out.** You'll find this easiest to do if the flash lighting the backdrop is at full power (assuming it isn't too bright as to create a lot of spill back onto your subject).
**If the dimmest part of the backdrop is pure white in your resulting photo the entire backdrop will be pure white. There's no way for the brighter parts of the backdrop to be brighter or whiter than pure white in the resulting image.**
Once you've got the exposure right for the backdrop you can then adjust the power of the other light(s) to properly expose your subject at the same ISO and aperture. | >
> all depending where I put the tripod that holds it
>
>
>
Ok I think the answer is... change where you put the tripod that holds it.
But I assume this is limited due the total space between the model and the background.
If you increase the distance between the model and the background you have space to put the flash **directly behind the model**. Experiment with distances, for example if your model is 1.5 mts tall, put your model 1.5 mts away from the background and the flash just behind. Try other distances for example 1.5x or 2x the height of the model.
This distance also helps reducing the reflected light to wrap arround your model.
Aditionally very important!:
* Change the zoom range on the flash to the smallest number. That makes the light spread more.
* Pull the little transparent grid the flash itself has and leave it infront of the flash strobe.
* Use the flash in the same orientation as your image.
* You can also use a pice of vegetal paper in front of the flash.
As you are using the flash exactly behind the subject you can not have an umbrella.
If you want to use an umbrella you need more than one.
One important thing is that you can not use a very wide lens... Imagine you want to shoot with a fish lens, of course at 2 mts you can not have an even backdrop. Try to use at least 50mm lens. The longer the better.
---
You need first of all to learn how to take a photo of a simple white background with no model. The result is a pretty boring white photo, but you need to know it.
This distance afects the total brightness of the background. Start for example at 1/32 the total power of the flash.
At 1.5 mts away and 1/16 I can blow a white background at f5.6. Iso 400 (rough estimation).
So you have room to play: f/8? use 1/8. f/11? Use 1/4.
It is also important that your background is white and **diffusive**.
A coated paper or plastic is NOT good. This makes hotspots and the edges look gray. |
277,261 | First of all sorry for this basic question.
---
Newton's third law states that for every force there is a force, which is equal in magnitude and opposite in direction to those of given force.So by that logic friction should also have a reaction force.
Now my questions are, what is the reaction force for static friction ?
For instance in the picture, what is the direction of reaction force of static friction and on which object will that force act ?
[](https://i.stack.imgur.com/aJ7Gc.png) | 2016/08/30 | [
"https://physics.stackexchange.com/questions/277261",
"https://physics.stackexchange.com",
"https://physics.stackexchange.com/users/-1/"
] | There is no reaction force on this free body diagram. That is because this is the diagram for the object only.
Draw a free body diagram of the Earth, and **there** you have your reaction force. You will see that the same static friction pulls the opposite way in the Earth.
Free-body force diagrams tell a story about one object (or system) and are thus useful for e.g. Newton's 2nd and 1st laws. But the action/reaction force couples that come from Newton's third law appear *between* objects, or you could say that they appear on *two different* objects. Not on the same objects. Therefor they might not both be included within a free-body diagram - if they *are* both included (when you define your system as including both objects), then they will always exactly cancel out and will thus make no different for Newton's 2nd and 1st laws, and thus we ignore them. You will thus never see an action/reaction force pair both appearing on a free-body diagram.
To explain your specific scenario: The static friction force is **trying to prevent sliding from happening**. So it pulls *leftwards* in the box in order to try to prevent it from moving, and it pulls *rightwards* in the Earth to try to make the Earth follow along with the box, so that there is no sliding. | If the object stays stationary and no force acting on it, there is no frictional force on it (static or kinetic). However when the force is applied from zero, until the object just starts moving, the static frictional force is acting on the object and **increasing** in magnitude. The direction is equal and opposite to the applied force until critical point is reached (where it starts moving) hence that obeys newton's third law. |
277,261 | First of all sorry for this basic question.
---
Newton's third law states that for every force there is a force, which is equal in magnitude and opposite in direction to those of given force.So by that logic friction should also have a reaction force.
Now my questions are, what is the reaction force for static friction ?
For instance in the picture, what is the direction of reaction force of static friction and on which object will that force act ?
[](https://i.stack.imgur.com/aJ7Gc.png) | 2016/08/30 | [
"https://physics.stackexchange.com/questions/277261",
"https://physics.stackexchange.com",
"https://physics.stackexchange.com/users/-1/"
] | There is no reaction force on this free body diagram. That is because this is the diagram for the object only.
Draw a free body diagram of the Earth, and **there** you have your reaction force. You will see that the same static friction pulls the opposite way in the Earth.
Free-body force diagrams tell a story about one object (or system) and are thus useful for e.g. Newton's 2nd and 1st laws. But the action/reaction force couples that come from Newton's third law appear *between* objects, or you could say that they appear on *two different* objects. Not on the same objects. Therefor they might not both be included within a free-body diagram - if they *are* both included (when you define your system as including both objects), then they will always exactly cancel out and will thus make no different for Newton's 2nd and 1st laws, and thus we ignore them. You will thus never see an action/reaction force pair both appearing on a free-body diagram.
To explain your specific scenario: The static friction force is **trying to prevent sliding from happening**. So it pulls *leftwards* in the box in order to try to prevent it from moving, and it pulls *rightwards* in the Earth to try to make the Earth follow along with the box, so that there is no sliding. | The red arrow is presumably the force on the block due to the table. It is a friction force.
By Newton's third law, there is a force on the table due to the block. It points to the right. It is a friction force.
You drew your diagram with a bit of an ambiguity. You drew the red arrow right on the interface between the block and the table, so it is not clear which object that force is acting on. To be clearer, you should draw the red arrow unambiguously connected to the block. The reaction force would be drawn as an arrow pointing to the right *unambiguously attached to the table*. |
277,261 | First of all sorry for this basic question.
---
Newton's third law states that for every force there is a force, which is equal in magnitude and opposite in direction to those of given force.So by that logic friction should also have a reaction force.
Now my questions are, what is the reaction force for static friction ?
For instance in the picture, what is the direction of reaction force of static friction and on which object will that force act ?
[](https://i.stack.imgur.com/aJ7Gc.png) | 2016/08/30 | [
"https://physics.stackexchange.com/questions/277261",
"https://physics.stackexchange.com",
"https://physics.stackexchange.com/users/-1/"
] | There is no reaction force on this free body diagram. That is because this is the diagram for the object only.
Draw a free body diagram of the Earth, and **there** you have your reaction force. You will see that the same static friction pulls the opposite way in the Earth.
Free-body force diagrams tell a story about one object (or system) and are thus useful for e.g. Newton's 2nd and 1st laws. But the action/reaction force couples that come from Newton's third law appear *between* objects, or you could say that they appear on *two different* objects. Not on the same objects. Therefor they might not both be included within a free-body diagram - if they *are* both included (when you define your system as including both objects), then they will always exactly cancel out and will thus make no different for Newton's 2nd and 1st laws, and thus we ignore them. You will thus never see an action/reaction force pair both appearing on a free-body diagram.
To explain your specific scenario: The static friction force is **trying to prevent sliding from happening**. So it pulls *leftwards* in the box in order to try to prevent it from moving, and it pulls *rightwards* in the Earth to try to make the Earth follow along with the box, so that there is no sliding. | I am just giving anology for the problem. Frictional force arise due to surface roughness so both surface create frictional forces in action-reaction pair, surface1 for surface2 and vice versa. You can imagine dragging two sandpapers onto each other to figure out direction of frictional forces in pair. Therefore ground is acting on box in left direction and box is acting on ground in right direction. |
14,339,201 | I am dealing with a project related to Embedded System.
I want my controller(89c51 micro-controller) to respond(do the programmed actions) when I'll click on a button(GUI designed in .NET technology). Tell me programming language to write code for controller.
What should I do for, 'my hardware-part to respond according to click event on GUI/Button (Designed in .NET)
Also tell me the supposed steps(for compiling & burning code on Controller) so that I could communicate with the micro-controller on an event. I'll also like to know the necessary tools that I must have, if any.
Thank you. | 2013/01/15 | [
"https://Stackoverflow.com/questions/14339201",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/1980424/"
] | I guess that you are asking about how to establish a connection to the [AT89C51](http://www.atmel.com/images/doc0265.pdf) (click for data sheet).
The AT89C51 seems to come with a serial port on Port 3. You will need C to program the micro-controller itself, but can establish a serial connection to Port 3 using C#.
See this class for reference and examples on how to establish a serial connection using C#: [System.IO.Ports.SerialPort](http://msdn.microsoft.com/en-us/library/system.io.ports.serialport.aspx) | This won't work, because you can't (with common compilers) compile C# into native code the embedded system understands. C# compiles to an intermediate code (MSIL/CIL), that is then compiled/executed by the runtime environment (which you won't have in most embedded system).
When programming for real-time embedded systems, there's usually no way around assembly (or C/C++ if you're lucky) unless your platform explicitly supports/is based on the .NET Micro Framework, which will also only support a specific subset of the whole .NET runtime available on desktop machines |
14,339,201 | I am dealing with a project related to Embedded System.
I want my controller(89c51 micro-controller) to respond(do the programmed actions) when I'll click on a button(GUI designed in .NET technology). Tell me programming language to write code for controller.
What should I do for, 'my hardware-part to respond according to click event on GUI/Button (Designed in .NET)
Also tell me the supposed steps(for compiling & burning code on Controller) so that I could communicate with the micro-controller on an event. I'll also like to know the necessary tools that I must have, if any.
Thank you. | 2013/01/15 | [
"https://Stackoverflow.com/questions/14339201",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/1980424/"
] | Not possible with an 89C51 as its only an 8bit processor.
If you want to run embedded C# you need something like a netduino or GHI fez board, which are low cost .net micro framework development boards.
If the question is asking how to connect to the MCU via C# then as stated program MCU to enable serial functionality, then write in C# a serial application using the System.IO.Ports.SerialPort class. | This won't work, because you can't (with common compilers) compile C# into native code the embedded system understands. C# compiles to an intermediate code (MSIL/CIL), that is then compiled/executed by the runtime environment (which you won't have in most embedded system).
When programming for real-time embedded systems, there's usually no way around assembly (or C/C++ if you're lucky) unless your platform explicitly supports/is based on the .NET Micro Framework, which will also only support a specific subset of the whole .NET runtime available on desktop machines |
3,701,521 | I have a code-base of legacy C/C++ code, which contains lots of functions that access global static variables, and are therefore not thread-safe. I'm looking for advice on how to convert this code to make it thread safe. It occurs to me that one way to do it would be to convert the static variables into thread-local variables, or otherwise store them in thread-local storage. This has the advantage that I don't have to rewrite a lot of code that uses the functions to pass extra context to them, just the thread-unsafe functions themselves. But in researching this, I haven't found a lot of advice on whether this is a good or bad idea. Some specific concerns I have are
* will the accessing of TLS-based data be significantly slower?
* am I just continuing to fall into the trap of using global variables, since "global variables are bad", or does TLS counteract the global-variables-are-bad argument?
Any other thoughts would be appreciated too. | 2010/09/13 | [
"https://Stackoverflow.com/questions/3701521",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/4928/"
] | First of all, it's best to determine which global variables are accessed in a mutable fashion and which are not. There could be several cases where the variables are not actually modified once set, just that the initialization of those variables will now pose problems for a non-deterministic program. Those variables, where initialization order will matter, I'd place in their own class which could be propagated to each individual thread which needs them.
After that, I'm sure your problems will only compound themselves. I've been where you are and my sympathies. | Well, it'd be pretty easy to start there. You could just have a conditional compile for thread-local. Some compilers e.g. Visual Studio have their own thread\_local storage that you can just drop in. |
3,701,521 | I have a code-base of legacy C/C++ code, which contains lots of functions that access global static variables, and are therefore not thread-safe. I'm looking for advice on how to convert this code to make it thread safe. It occurs to me that one way to do it would be to convert the static variables into thread-local variables, or otherwise store them in thread-local storage. This has the advantage that I don't have to rewrite a lot of code that uses the functions to pass extra context to them, just the thread-unsafe functions themselves. But in researching this, I haven't found a lot of advice on whether this is a good or bad idea. Some specific concerns I have are
* will the accessing of TLS-based data be significantly slower?
* am I just continuing to fall into the trap of using global variables, since "global variables are bad", or does TLS counteract the global-variables-are-bad argument?
Any other thoughts would be appreciated too. | 2010/09/13 | [
"https://Stackoverflow.com/questions/3701521",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/4928/"
] | First of all, it's best to determine which global variables are accessed in a mutable fashion and which are not. There could be several cases where the variables are not actually modified once set, just that the initialization of those variables will now pose problems for a non-deterministic program. Those variables, where initialization order will matter, I'd place in their own class which could be propagated to each individual thread which needs them.
After that, I'm sure your problems will only compound themselves. I've been where you are and my sympathies. | In terms of correctness I see no reason that this wouldn't work, as long as the threading doesn't have other implications that could cause conflicts. You'd need to make sure you caught *all* the globals and converted them.
The best way to determine if it's significantly slower would be to profile a converted section of the code and see.
That being said I don't know that this is the best solution. Global variables are just that, regardless of what they're called, and they make tracking program state and debugging a total nightmare. I would seriously suggest taking a long look at the code and refactoring one piece at a time into thread-safe code that doesn't rely on globals. You'll have a much easier time debugging and future maintainers (or yourself) will thank you several years from now. |
3,701,521 | I have a code-base of legacy C/C++ code, which contains lots of functions that access global static variables, and are therefore not thread-safe. I'm looking for advice on how to convert this code to make it thread safe. It occurs to me that one way to do it would be to convert the static variables into thread-local variables, or otherwise store them in thread-local storage. This has the advantage that I don't have to rewrite a lot of code that uses the functions to pass extra context to them, just the thread-unsafe functions themselves. But in researching this, I haven't found a lot of advice on whether this is a good or bad idea. Some specific concerns I have are
* will the accessing of TLS-based data be significantly slower?
* am I just continuing to fall into the trap of using global variables, since "global variables are bad", or does TLS counteract the global-variables-are-bad argument?
Any other thoughts would be appreciated too. | 2010/09/13 | [
"https://Stackoverflow.com/questions/3701521",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/4928/"
] | First of all, it's best to determine which global variables are accessed in a mutable fashion and which are not. There could be several cases where the variables are not actually modified once set, just that the initialization of those variables will now pose problems for a non-deterministic program. Those variables, where initialization order will matter, I'd place in their own class which could be propagated to each individual thread which needs them.
After that, I'm sure your problems will only compound themselves. I've been where you are and my sympathies. | Without understanding the semantics of **every** variable that you plan to convert, simply automating the conversion from global to TLS is likely to be a huge unproductive timesink. Some of them may need to remain global and be handled in a thread-safe way - others may be quite safe to use as TLS. Still more may be thread-safe as TLS, but result in a bad unscalable design as you increase the number of threads (eg. one socket per client/thread in a previously single-client single-threaded sockets server).
What is your platform/compiler of choice here btw? |
3,701,521 | I have a code-base of legacy C/C++ code, which contains lots of functions that access global static variables, and are therefore not thread-safe. I'm looking for advice on how to convert this code to make it thread safe. It occurs to me that one way to do it would be to convert the static variables into thread-local variables, or otherwise store them in thread-local storage. This has the advantage that I don't have to rewrite a lot of code that uses the functions to pass extra context to them, just the thread-unsafe functions themselves. But in researching this, I haven't found a lot of advice on whether this is a good or bad idea. Some specific concerns I have are
* will the accessing of TLS-based data be significantly slower?
* am I just continuing to fall into the trap of using global variables, since "global variables are bad", or does TLS counteract the global-variables-are-bad argument?
Any other thoughts would be appreciated too. | 2010/09/13 | [
"https://Stackoverflow.com/questions/3701521",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/4928/"
] | First of all, it's best to determine which global variables are accessed in a mutable fashion and which are not. There could be several cases where the variables are not actually modified once set, just that the initialization of those variables will now pose problems for a non-deterministic program. Those variables, where initialization order will matter, I'd place in their own class which could be propagated to each individual thread which needs them.
After that, I'm sure your problems will only compound themselves. I've been where you are and my sympathies. | Rather than storing all of the variables in thread-local storage, I would think it better to put them into a class; if the original code was mostly C, one may be able to wrap the C code in a class which can then have the "global" variables as fields. Different instances of the class running in different threads would naturally see different versions of those variables. |
3,701,521 | I have a code-base of legacy C/C++ code, which contains lots of functions that access global static variables, and are therefore not thread-safe. I'm looking for advice on how to convert this code to make it thread safe. It occurs to me that one way to do it would be to convert the static variables into thread-local variables, or otherwise store them in thread-local storage. This has the advantage that I don't have to rewrite a lot of code that uses the functions to pass extra context to them, just the thread-unsafe functions themselves. But in researching this, I haven't found a lot of advice on whether this is a good or bad idea. Some specific concerns I have are
* will the accessing of TLS-based data be significantly slower?
* am I just continuing to fall into the trap of using global variables, since "global variables are bad", or does TLS counteract the global-variables-are-bad argument?
Any other thoughts would be appreciated too. | 2010/09/13 | [
"https://Stackoverflow.com/questions/3701521",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/4928/"
] | The problem with using TLS is that you force thread affinity onto your clients, and they have to be aware of this and write their code to handle it accordingly. So if they have a worker thread that does the heavy lifting then they will have to marshal ALL calls to your library onto that worker thread, even for simple getters and setters. Or if some other component calls into their component on a thread pool thread (for instance) then they will have to marshal that call onto their worker thread. It's not the worst thing in the world, but it can be very inconvenient. I definitely prefer the handle/context pattern (I maintain a library that uses TLS and it has been a chore at times dealing with thread affinity). | Well, it'd be pretty easy to start there. You could just have a conditional compile for thread-local. Some compilers e.g. Visual Studio have their own thread\_local storage that you can just drop in. |
3,701,521 | I have a code-base of legacy C/C++ code, which contains lots of functions that access global static variables, and are therefore not thread-safe. I'm looking for advice on how to convert this code to make it thread safe. It occurs to me that one way to do it would be to convert the static variables into thread-local variables, or otherwise store them in thread-local storage. This has the advantage that I don't have to rewrite a lot of code that uses the functions to pass extra context to them, just the thread-unsafe functions themselves. But in researching this, I haven't found a lot of advice on whether this is a good or bad idea. Some specific concerns I have are
* will the accessing of TLS-based data be significantly slower?
* am I just continuing to fall into the trap of using global variables, since "global variables are bad", or does TLS counteract the global-variables-are-bad argument?
Any other thoughts would be appreciated too. | 2010/09/13 | [
"https://Stackoverflow.com/questions/3701521",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/4928/"
] | The problem with using TLS is that you force thread affinity onto your clients, and they have to be aware of this and write their code to handle it accordingly. So if they have a worker thread that does the heavy lifting then they will have to marshal ALL calls to your library onto that worker thread, even for simple getters and setters. Or if some other component calls into their component on a thread pool thread (for instance) then they will have to marshal that call onto their worker thread. It's not the worst thing in the world, but it can be very inconvenient. I definitely prefer the handle/context pattern (I maintain a library that uses TLS and it has been a chore at times dealing with thread affinity). | In terms of correctness I see no reason that this wouldn't work, as long as the threading doesn't have other implications that could cause conflicts. You'd need to make sure you caught *all* the globals and converted them.
The best way to determine if it's significantly slower would be to profile a converted section of the code and see.
That being said I don't know that this is the best solution. Global variables are just that, regardless of what they're called, and they make tracking program state and debugging a total nightmare. I would seriously suggest taking a long look at the code and refactoring one piece at a time into thread-safe code that doesn't rely on globals. You'll have a much easier time debugging and future maintainers (or yourself) will thank you several years from now. |
3,701,521 | I have a code-base of legacy C/C++ code, which contains lots of functions that access global static variables, and are therefore not thread-safe. I'm looking for advice on how to convert this code to make it thread safe. It occurs to me that one way to do it would be to convert the static variables into thread-local variables, or otherwise store them in thread-local storage. This has the advantage that I don't have to rewrite a lot of code that uses the functions to pass extra context to them, just the thread-unsafe functions themselves. But in researching this, I haven't found a lot of advice on whether this is a good or bad idea. Some specific concerns I have are
* will the accessing of TLS-based data be significantly slower?
* am I just continuing to fall into the trap of using global variables, since "global variables are bad", or does TLS counteract the global-variables-are-bad argument?
Any other thoughts would be appreciated too. | 2010/09/13 | [
"https://Stackoverflow.com/questions/3701521",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/4928/"
] | The problem with using TLS is that you force thread affinity onto your clients, and they have to be aware of this and write their code to handle it accordingly. So if they have a worker thread that does the heavy lifting then they will have to marshal ALL calls to your library onto that worker thread, even for simple getters and setters. Or if some other component calls into their component on a thread pool thread (for instance) then they will have to marshal that call onto their worker thread. It's not the worst thing in the world, but it can be very inconvenient. I definitely prefer the handle/context pattern (I maintain a library that uses TLS and it has been a chore at times dealing with thread affinity). | Without understanding the semantics of **every** variable that you plan to convert, simply automating the conversion from global to TLS is likely to be a huge unproductive timesink. Some of them may need to remain global and be handled in a thread-safe way - others may be quite safe to use as TLS. Still more may be thread-safe as TLS, but result in a bad unscalable design as you increase the number of threads (eg. one socket per client/thread in a previously single-client single-threaded sockets server).
What is your platform/compiler of choice here btw? |
3,701,521 | I have a code-base of legacy C/C++ code, which contains lots of functions that access global static variables, and are therefore not thread-safe. I'm looking for advice on how to convert this code to make it thread safe. It occurs to me that one way to do it would be to convert the static variables into thread-local variables, or otherwise store them in thread-local storage. This has the advantage that I don't have to rewrite a lot of code that uses the functions to pass extra context to them, just the thread-unsafe functions themselves. But in researching this, I haven't found a lot of advice on whether this is a good or bad idea. Some specific concerns I have are
* will the accessing of TLS-based data be significantly slower?
* am I just continuing to fall into the trap of using global variables, since "global variables are bad", or does TLS counteract the global-variables-are-bad argument?
Any other thoughts would be appreciated too. | 2010/09/13 | [
"https://Stackoverflow.com/questions/3701521",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/4928/"
] | The problem with using TLS is that you force thread affinity onto your clients, and they have to be aware of this and write their code to handle it accordingly. So if they have a worker thread that does the heavy lifting then they will have to marshal ALL calls to your library onto that worker thread, even for simple getters and setters. Or if some other component calls into their component on a thread pool thread (for instance) then they will have to marshal that call onto their worker thread. It's not the worst thing in the world, but it can be very inconvenient. I definitely prefer the handle/context pattern (I maintain a library that uses TLS and it has been a chore at times dealing with thread affinity). | Rather than storing all of the variables in thread-local storage, I would think it better to put them into a class; if the original code was mostly C, one may be able to wrap the C code in a class which can then have the "global" variables as fields. Different instances of the class running in different threads would naturally see different versions of those variables. |
181,825 | I am a final year student doing Masters and had applied for a job. An HR contacted me after a month and scheduled an interview call but kept on rescheduling it at the last moment twice a week for two weeks (every time saying something urgent came up in an unplanned way), after which I sent a declination.
What can be the reason or meaning of repeatedly booking time for interview (the calendar request shows only me and the HR herself) just to keep rescheduling it? And is it unprofessional if I ask her not to contact me again if she intends to waste time this way?
Following are the detailed sequence of events happened.
Day 1 : I got a missed call at 5 pm, and a mail saying 'I am HR of XYZ company, trying to reach you in regard of your job application. Please call me back during my working hours 9 am - 5 pm.'
Day 2 : I call her at 4:45 pm and found out she had already left office, and will call back later today/tomorrow.
Day 3 : I wait. Send a mail at 4 pm, before entering into a class, specifying my free times for next 3 days.
Day 4 : The HR called. I told her that my course will be over after 7 months from now, she enquires if I am sitting for a campus interview and if I have already got one. She says I should keep her informed about the status of my campus interviews and if I want to get in touch with her after 3-4 months. As I am really interested in the area this company works on, I told her so. She enquired about my free mornings and scheduled a call at 11:30 am for a technical interview and said it is an exploratory call.
Day 5 : At 9:15am a call from her, saying no interview today due to unavailability of interviewer's time, rescheduled to Thursday 11:30 am.
Day 6: At 11:15, a rescheduling mail, with new time as Tuesday 11:30 am next week. This time no call and no excuse given.
Day 7: At 11:30 am, a rescheduling mail, with new time as Thursday 11:30 am, with a note like "I am extremely sorry to reschedule your interview again, some urgent meeting came up." etc.
Day 8 : Waiting alone in the interview link at 11:30 am. Another rescheduling mail at 11:32 am, with a sorry note that something urgent came up.
I decline the meeting request with a note "Hello Mam, I was waiting at the hangout call. As it seems like you are busy now, I would request to connect after 3-4 months, as you were suggesting earlier. My exams are also nearby, I can't afford to wait for the interview and then get a reschedule call at all my free days, as I need to utilize them for advancing my studies"
On next Monday I get a mail like this "Sorry for the last-minute reschedules - we couldn't make it due to a medical emergency and I was unable to get in touch with you to inform you of the same.
I'll go ahead and put this on hold for a few months as discussed.
All the best for your exams!"
I am tempted to write a reply like this.
"Dear mam, hope you get well soon. Please contact me after 3-4 months, only if you are serious about taking my interview and recruiting me. I never saw any interviewer's time booked for these series of rescheduled meetings, and I believe you yourself was not intending to take my technical interview in machine learning. Requesting you not to waste my time anymore if you do not really intend to recruit me."
Will it be unprofessional to reply like this, and it is better to just not reply anything? | 2021/12/28 | [
"https://workplace.stackexchange.com/questions/181825",
"https://workplace.stackexchange.com",
"https://workplace.stackexchange.com/users/122728/"
] | **tldr: Professional means to focus on your goals & commitments and leave your emotions and fragile ego out of it.**
>
> Will it be unprofessional to reply like this,
>
>
>
Yes, very much so. It will guarantee that you will not get the job and you will come across as overly sensitive and spoiled.
>
> is better to just not reply anything?
>
>
>
No. It's most effective to send a friendly thank you e-mail like **"thanks for reaching out, I'd be happy to connect in a few months and I'm also available in between if that helps. Sorry about your medical emergency, I hope everyone is well ."**
So let's look at what happened here.
1. You want an exploratory chat with a company you are interested in and you actually got a foot in the door. Great !
2. You got contacted by an HR staffer. They have probably 25 other candidates they are working on and your potential employment is still 7 months out. That means you are on the BOTTOM of their priority list. Keep in mind that this is probably a first line staffer, who often are very junior and still learning the ropes as well.
3. The staffer tries a few times to arrange an interview but it doesn't work out and communication around it is suboptimal. While inconvenient, this actual fairly normal. You are a low priority hire and urgent things do indeed come up on a daily basis. Could also be bad luck, incompetence, internal miscommunication, actual medical emergencies. Who knows.
You have a couple of choices here
1. Throw a hissy fit and complain.
2. Become passive-aggressive and go to radio silence
3. Remain friendly and co-operative
I can't think of a scenario where #3 isn't the most effective option. It takes 5 minutes to write and you are still in the running. If you don't want the job anymore you can still say no later at the next step.
With the other two options you just come across as immature and unprofessional. No one wants to hire that. | Yes, it would be unprofessional to end this entire "almost, but not quite" process with the phrase "not waste my time."
To start with, being professional is basically "making it easy to get work done." Were you professional when you basically gave them one hour a week to be interviewed, at a time that crosses both 1/2 of the hour before lunch and 1/2 of lunch?
Also, it doesn't matter how many times you've communicated with them; because, it's more professional to communicate in ways that reduce the number of required communications.
So, before you worry about their professionalism, focus on what you can control. First decide if you want the job, and then decide what you want to do.
If you want the job, find three options to meet. Those options should be spread across at least two days, and should not all be in the same hour. Ideally you'd provide a morning and a "just after lunch" option; because those are easier for working people to commit to. "Just before you leave work" options are not great options, as by then one's probably tied up with the events of the day. Let them know if they can't make any of the options, they should give you three times to meet and you'll see if you can accommodate them.
If you don't want the job, then tell them it's just not the right time for you yet. You can't make them wait four months, their projects might not be able to wait that long; by then they might have already hired all the personnel they need.
To quote Winston Churchill, "Diplomacy is the art of telling people to go to hell in such a way that they ask for directions." Don't mess it up by saying they wasted your time, instead say what you really mean, "you don't want to interview for a job at this moment."
Saying they are wasting your time is judging them, which is entirely unnecessary and professionally dangerous. You might come off on the wrong side of public opinion, as who knows, maybe there was a car accident, emergency at their child's school, or some other item you'd normally forgive that got in the way of your phone call. I'd be very careful to avoid such judgements on so little information. |
700,423 | [Wordpress](http://wordpress.org/) is using [MyISAM](http://en.wikipedia.org/wiki/MyISAM) storage engine. MyISAM does not support transactions.
How wordpress is maintaining transactions?
I mean if wordpress is having two database write operations, how does it ensure atomicity? | 2009/03/31 | [
"https://Stackoverflow.com/questions/700423",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/48625/"
] | Well, as far as I can tell, it doesn't! The only reason there are not much problems with this is, that most write operations are done with a single insert or update (adding a comment, creating a new post...).
In general, most web applications I have seen so far, don't bother too much with transactions, atomicity or even referential integrity, which is quite sad. On the one hand it is sad that so many applications just rely on pure luck that nothing bad happens and on the other hand it might lead to the impression that all these techniques aren't that important when it comes to database stuff. | I would think the transaction would assure atomic correctness at the previous layer of abstraction. When a transaction is occurring it default locks what it is writing. I'm not sure though. |
79,033 | I'm looking for an appropriate (free) substitute for Montserrat italic. Now I'm using Noto Sans italic, but it doesn't look really good:
[](https://i.stack.imgur.com/WPFxB.png) | 2016/10/20 | [
"https://graphicdesign.stackexchange.com/questions/79033",
"https://graphicdesign.stackexchange.com",
"https://graphicdesign.stackexchange.com/users/56107/"
] | How about Raleway Medium Italic?
[](https://i.stack.imgur.com/pWCFy.png) | maybe pt sans but i found montserrat really thicker than other fonts. pt sans bold italic maybe |
63,801,307 | I am learning about data allocation and am a little confused.
If you are looking for the smallest or greatest value that can be stored in a certain number of bits then does it matter what the data type is?
Wouldn't the smallest or biggest number that could be stored in 22 bits would be 22 1's positive or negative? Is the first part of this question a red herring? Wouldn't the smallest value be -4194303? | 2020/09/08 | [
"https://Stackoverflow.com/questions/63801307",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/14244015/"
] | A 22-bit data element can store any one of 2^22 distinct values. What those values actually mean is a matter of interpretation. That interpretation may be imposed by a compiler or some piece of hardware, or may be under the control of the programmer, and suit some specific application.
A simple interpretation, of course, would be to treat the 22 bits as an unsigned integer, with values from 0 to (2^22)-1. A two's-complement, signed integer is a slightly more sophisticated interpretation of the same bits. Or you (or the compiler, or CPU) could divide the 22 bits up into a mantissa and exponent, and store a range of decimal numbers. The range and precision would depend on how many bits were allocated to the mantissa, and how many to the exponent.
Or you could split the bits up and use some for the numerator and some for the denominator of a fraction. Or, in fact, anything else.
Some of these interpretations of the bits are built into hardware, some are implemented by compilers or libraries, and some are entirely under the programmer's control. Not all programming languages allow the programmer to manipulate individual bits in a natural or efficient way, but some do. Sometimes, using a highly unconventional interpretation of binary data can give significant efficiency gains, but usually at the expense of readability and maintainability.
So, yes, it matters what the data type is. | There is no law (of humans, logic, or nature) that says bits must represent numbers only in the pattern that one of the bits represents 20, another represents 21, another represents 22, and so on (and the number represented is the sum of those values for the bits that are 1). We have choices about how to use bits to represent numbers, including:
* The bits do use that pattern, and so 22 bits can represent any number from 0 to the sum of 20 + 21 + 22 + … + 221 = 222 − 1 = 4,194,303. The smallest representable value is 0.
* The bits mostly use that pattern, but it is modified so that one bit represents −221 instead of +221. This is called *two’s complement*, and the smallest value representable is −221 = −2,097,152.
* The bits represent numbers as described above except the represent value is divided by 1000. This is called *fixed-point*. In the first case, the value represent by all bits 1 would be 4194.303, but the smallest representable value would be 0. With a combination of two’s complement and fixed-point scaled by 1/1000, the smallest representable value would be −2097.152.
* The bits represent a *floating-point* number, where one bit represents a sign (+ or −), certain bits represent an exponent and other information, and the remaining bits represent a *significand*. In common floating-point formats, when all the bits in that exponent-and-other field are 1s and the significand field bits are 0s, the number represents +∞ or −∞, according to the sign bit. In such a format, the smallest representable value is −∞.
* As an example, we could designate patterns of bits to represent numbers arbitrarily. We could say that 0000000000000000000000 represents 34, 0000000000000000000001 represents −15, 0000000000000000000010 represents 5, 0000000000000000000011 represents 3+4i, and so on. The smallest representable value would be whichever of those arbitrary values is smallest.
So what the smallest representable value is depends entirely on the *type*, since the “type” of the data includes the scheme by which the bits represent values.
If the type is a “signed integer type,” there is still some flexibility in the representation. Most modern C implementations (and other programming languages) use the two’s complement scheme described above. But the C standard still allows two other schemes:
* *One’s complement*: If the first bit is 1, the value represented is negative, and its magnitude is given by complementing the remaining bits and interpreting them as binary. Using six bits for an example, 101001 would be negative with the magnitude of 101102 = 22, so −22.
* *Sign-and-magnitude*: If the first bit is 1, the value represented is negative, and its magnitude is given by interpreting the remaining bits as binary. Using the same bits, 101001 would negative with the magnitude of 010012 = 9, so −9.
In both one’s complement and sign-and-magnitude, the smallest representable value with 22 bits is −(221−1) = −2,097,151.
To stretch the question further, C defines standard integer types but allows implementations to extend the language. An implementation could define some “signed integer type” with an arbitrary scheme for representing numbers, as long as that scheme included a sign, to make the name correct. |
63,801,307 | I am learning about data allocation and am a little confused.
If you are looking for the smallest or greatest value that can be stored in a certain number of bits then does it matter what the data type is?
Wouldn't the smallest or biggest number that could be stored in 22 bits would be 22 1's positive or negative? Is the first part of this question a red herring? Wouldn't the smallest value be -4194303? | 2020/09/08 | [
"https://Stackoverflow.com/questions/63801307",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/14244015/"
] | A 22-bit data element can store any one of 2^22 distinct values. What those values actually mean is a matter of interpretation. That interpretation may be imposed by a compiler or some piece of hardware, or may be under the control of the programmer, and suit some specific application.
A simple interpretation, of course, would be to treat the 22 bits as an unsigned integer, with values from 0 to (2^22)-1. A two's-complement, signed integer is a slightly more sophisticated interpretation of the same bits. Or you (or the compiler, or CPU) could divide the 22 bits up into a mantissa and exponent, and store a range of decimal numbers. The range and precision would depend on how many bits were allocated to the mantissa, and how many to the exponent.
Or you could split the bits up and use some for the numerator and some for the denominator of a fraction. Or, in fact, anything else.
Some of these interpretations of the bits are built into hardware, some are implemented by compilers or libraries, and some are entirely under the programmer's control. Not all programming languages allow the programmer to manipulate individual bits in a natural or efficient way, but some do. Sometimes, using a highly unconventional interpretation of binary data can give significant efficiency gains, but usually at the expense of readability and maintainability.
So, yes, it matters what the data type is. | Without going into technical jargon about doing maths with Two's compliment, I'll try to explain in easy words.
First you need to raise 2 with power of 'number of bits'.
Let's take an example of an 8 bit type,
An un-signed 8-bit integer can store 2 ^ 8 = 256 values.
Since values are indexed starting from 0, so values range from 0 - 255.
Assuming you want to store signed values, so you need to get the half (simply divide it by 2),
256 / 2 = 128.
Remember we start from zero,
You might be rightly thinking you can store -127 to 127 starting from zero on both sides.
Just know that there is only zero (there is nothing like +0 or -0),
so you start with zero to positive half. 0 to 127,
that leaves you with negative half starting from -1 to -128
Hence the range will be -128 to 127.
For a 22 bit signed integer you can do the math,
2 ^ 22 = 4,194,304
4194304 / 2 = 2,097,152
-1 for positive side,
range will be, -2097152 to 2097151.
To answer your question,
-2097152 would be the smallest number you can store. |
63,801,307 | I am learning about data allocation and am a little confused.
If you are looking for the smallest or greatest value that can be stored in a certain number of bits then does it matter what the data type is?
Wouldn't the smallest or biggest number that could be stored in 22 bits would be 22 1's positive or negative? Is the first part of this question a red herring? Wouldn't the smallest value be -4194303? | 2020/09/08 | [
"https://Stackoverflow.com/questions/63801307",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/14244015/"
] | A 22-bit data element can store any one of 2^22 distinct values. What those values actually mean is a matter of interpretation. That interpretation may be imposed by a compiler or some piece of hardware, or may be under the control of the programmer, and suit some specific application.
A simple interpretation, of course, would be to treat the 22 bits as an unsigned integer, with values from 0 to (2^22)-1. A two's-complement, signed integer is a slightly more sophisticated interpretation of the same bits. Or you (or the compiler, or CPU) could divide the 22 bits up into a mantissa and exponent, and store a range of decimal numbers. The range and precision would depend on how many bits were allocated to the mantissa, and how many to the exponent.
Or you could split the bits up and use some for the numerator and some for the denominator of a fraction. Or, in fact, anything else.
Some of these interpretations of the bits are built into hardware, some are implemented by compilers or libraries, and some are entirely under the programmer's control. Not all programming languages allow the programmer to manipulate individual bits in a natural or efficient way, but some do. Sometimes, using a highly unconventional interpretation of binary data can give significant efficiency gains, but usually at the expense of readability and maintainability.
So, yes, it matters what the data type is. | Thanks everyone for the replies. I figured it out with the help of all of your info but I will explain the answer to show exactly what gaps of knowledge I had that lead to my misunderstanding.
The data type does matter in this question because for signed data types the first bit is used to represent whether or not a binary number is positive or negative. 0111 = 7 and 1111 = -7
sign int and unsigned int use the same number of bits, 32 bits. Since an unsigned int is unsigned: the first bit isn't used to represent positive or negative so it can represent a larger number with that extra bit. 1111 converted to an unsigned int is 15 whereas with the signed int it was -7 since the furthest left bit represents the sign: 1 is negative and 0 is positive.
Now to answer "If a C signed integer type is stored in 22 bits, what is the smallest value it can store?":
If you convert binary to decimal you get 1111111111111111111111 = 4194304
This decimal value -1 is the maximum value an unsigned could hold. Since our data type is signed it has to use one less bit for the number value since the first bit represents the sign. This gives us -2097152.
Thanks again, everyone. |
63,801,307 | I am learning about data allocation and am a little confused.
If you are looking for the smallest or greatest value that can be stored in a certain number of bits then does it matter what the data type is?
Wouldn't the smallest or biggest number that could be stored in 22 bits would be 22 1's positive or negative? Is the first part of this question a red herring? Wouldn't the smallest value be -4194303? | 2020/09/08 | [
"https://Stackoverflow.com/questions/63801307",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/14244015/"
] | There is no law (of humans, logic, or nature) that says bits must represent numbers only in the pattern that one of the bits represents 20, another represents 21, another represents 22, and so on (and the number represented is the sum of those values for the bits that are 1). We have choices about how to use bits to represent numbers, including:
* The bits do use that pattern, and so 22 bits can represent any number from 0 to the sum of 20 + 21 + 22 + … + 221 = 222 − 1 = 4,194,303. The smallest representable value is 0.
* The bits mostly use that pattern, but it is modified so that one bit represents −221 instead of +221. This is called *two’s complement*, and the smallest value representable is −221 = −2,097,152.
* The bits represent numbers as described above except the represent value is divided by 1000. This is called *fixed-point*. In the first case, the value represent by all bits 1 would be 4194.303, but the smallest representable value would be 0. With a combination of two’s complement and fixed-point scaled by 1/1000, the smallest representable value would be −2097.152.
* The bits represent a *floating-point* number, where one bit represents a sign (+ or −), certain bits represent an exponent and other information, and the remaining bits represent a *significand*. In common floating-point formats, when all the bits in that exponent-and-other field are 1s and the significand field bits are 0s, the number represents +∞ or −∞, according to the sign bit. In such a format, the smallest representable value is −∞.
* As an example, we could designate patterns of bits to represent numbers arbitrarily. We could say that 0000000000000000000000 represents 34, 0000000000000000000001 represents −15, 0000000000000000000010 represents 5, 0000000000000000000011 represents 3+4i, and so on. The smallest representable value would be whichever of those arbitrary values is smallest.
So what the smallest representable value is depends entirely on the *type*, since the “type” of the data includes the scheme by which the bits represent values.
If the type is a “signed integer type,” there is still some flexibility in the representation. Most modern C implementations (and other programming languages) use the two’s complement scheme described above. But the C standard still allows two other schemes:
* *One’s complement*: If the first bit is 1, the value represented is negative, and its magnitude is given by complementing the remaining bits and interpreting them as binary. Using six bits for an example, 101001 would be negative with the magnitude of 101102 = 22, so −22.
* *Sign-and-magnitude*: If the first bit is 1, the value represented is negative, and its magnitude is given by interpreting the remaining bits as binary. Using the same bits, 101001 would negative with the magnitude of 010012 = 9, so −9.
In both one’s complement and sign-and-magnitude, the smallest representable value with 22 bits is −(221−1) = −2,097,151.
To stretch the question further, C defines standard integer types but allows implementations to extend the language. An implementation could define some “signed integer type” with an arbitrary scheme for representing numbers, as long as that scheme included a sign, to make the name correct. | Without going into technical jargon about doing maths with Two's compliment, I'll try to explain in easy words.
First you need to raise 2 with power of 'number of bits'.
Let's take an example of an 8 bit type,
An un-signed 8-bit integer can store 2 ^ 8 = 256 values.
Since values are indexed starting from 0, so values range from 0 - 255.
Assuming you want to store signed values, so you need to get the half (simply divide it by 2),
256 / 2 = 128.
Remember we start from zero,
You might be rightly thinking you can store -127 to 127 starting from zero on both sides.
Just know that there is only zero (there is nothing like +0 or -0),
so you start with zero to positive half. 0 to 127,
that leaves you with negative half starting from -1 to -128
Hence the range will be -128 to 127.
For a 22 bit signed integer you can do the math,
2 ^ 22 = 4,194,304
4194304 / 2 = 2,097,152
-1 for positive side,
range will be, -2097152 to 2097151.
To answer your question,
-2097152 would be the smallest number you can store. |
63,801,307 | I am learning about data allocation and am a little confused.
If you are looking for the smallest or greatest value that can be stored in a certain number of bits then does it matter what the data type is?
Wouldn't the smallest or biggest number that could be stored in 22 bits would be 22 1's positive or negative? Is the first part of this question a red herring? Wouldn't the smallest value be -4194303? | 2020/09/08 | [
"https://Stackoverflow.com/questions/63801307",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/14244015/"
] | There is no law (of humans, logic, or nature) that says bits must represent numbers only in the pattern that one of the bits represents 20, another represents 21, another represents 22, and so on (and the number represented is the sum of those values for the bits that are 1). We have choices about how to use bits to represent numbers, including:
* The bits do use that pattern, and so 22 bits can represent any number from 0 to the sum of 20 + 21 + 22 + … + 221 = 222 − 1 = 4,194,303. The smallest representable value is 0.
* The bits mostly use that pattern, but it is modified so that one bit represents −221 instead of +221. This is called *two’s complement*, and the smallest value representable is −221 = −2,097,152.
* The bits represent numbers as described above except the represent value is divided by 1000. This is called *fixed-point*. In the first case, the value represent by all bits 1 would be 4194.303, but the smallest representable value would be 0. With a combination of two’s complement and fixed-point scaled by 1/1000, the smallest representable value would be −2097.152.
* The bits represent a *floating-point* number, where one bit represents a sign (+ or −), certain bits represent an exponent and other information, and the remaining bits represent a *significand*. In common floating-point formats, when all the bits in that exponent-and-other field are 1s and the significand field bits are 0s, the number represents +∞ or −∞, according to the sign bit. In such a format, the smallest representable value is −∞.
* As an example, we could designate patterns of bits to represent numbers arbitrarily. We could say that 0000000000000000000000 represents 34, 0000000000000000000001 represents −15, 0000000000000000000010 represents 5, 0000000000000000000011 represents 3+4i, and so on. The smallest representable value would be whichever of those arbitrary values is smallest.
So what the smallest representable value is depends entirely on the *type*, since the “type” of the data includes the scheme by which the bits represent values.
If the type is a “signed integer type,” there is still some flexibility in the representation. Most modern C implementations (and other programming languages) use the two’s complement scheme described above. But the C standard still allows two other schemes:
* *One’s complement*: If the first bit is 1, the value represented is negative, and its magnitude is given by complementing the remaining bits and interpreting them as binary. Using six bits for an example, 101001 would be negative with the magnitude of 101102 = 22, so −22.
* *Sign-and-magnitude*: If the first bit is 1, the value represented is negative, and its magnitude is given by interpreting the remaining bits as binary. Using the same bits, 101001 would negative with the magnitude of 010012 = 9, so −9.
In both one’s complement and sign-and-magnitude, the smallest representable value with 22 bits is −(221−1) = −2,097,151.
To stretch the question further, C defines standard integer types but allows implementations to extend the language. An implementation could define some “signed integer type” with an arbitrary scheme for representing numbers, as long as that scheme included a sign, to make the name correct. | Thanks everyone for the replies. I figured it out with the help of all of your info but I will explain the answer to show exactly what gaps of knowledge I had that lead to my misunderstanding.
The data type does matter in this question because for signed data types the first bit is used to represent whether or not a binary number is positive or negative. 0111 = 7 and 1111 = -7
sign int and unsigned int use the same number of bits, 32 bits. Since an unsigned int is unsigned: the first bit isn't used to represent positive or negative so it can represent a larger number with that extra bit. 1111 converted to an unsigned int is 15 whereas with the signed int it was -7 since the furthest left bit represents the sign: 1 is negative and 0 is positive.
Now to answer "If a C signed integer type is stored in 22 bits, what is the smallest value it can store?":
If you convert binary to decimal you get 1111111111111111111111 = 4194304
This decimal value -1 is the maximum value an unsigned could hold. Since our data type is signed it has to use one less bit for the number value since the first bit represents the sign. This gives us -2097152.
Thanks again, everyone. |
150,581 | I want to check an IGBT FGA25N120ANTD whether it is broken or not. I have a good multimeter.
I followed some online videos I cannot figure out the right way.
Could you please help? | 2015/01/23 | [
"https://electronics.stackexchange.com/questions/150581",
"https://electronics.stackexchange.com",
"https://electronics.stackexchange.com/users/64018/"
] | There are 5 tests you can perform
1) impedance check
Collector-Emitter - should be Megs
Gate-Emitter - should be megs unless internal GE terminator resistor
2) Capacitive check
Gate-Emitter - should be capacitive ... (read further down)
3) Diode check
DMM on diode and Emitter - collector - should be a diode
4) withstand
Megger on 500V (or suitable level for the breakdown voltage BUT less than) Collector-Emitter
5) switch test
20V PSU Collector-Emitter with say... 1A limit, 15V PSU Gate-Emitter - 1st PSU should go into current limit
Do these tests on a known working switch so you know what to expect. | Try a diode check across the collector and emitter. If the IGBT is dead, it should read 0 volts. |
308,615 | Please feel free to correct me if I am wrong at any point...
I am trying to read a [CSV](http://en.wikipedia.org/wiki/Comma-separated_values) (comma separated values) file using .NET file I/O classes. Now the problem is, this CSV file may contain some fields with soft carriage returns (i.e. solitary \r or \n markers rather than the standard \r\n used in text files to end a line) within some fields and the standard text mode I/O class StreamReader does not respect the standard convention and treats the soft carriage returns as hard carriage returns thus compromising the integrity of the CSV file.
Now using the BinaryReader class seems to be the only option left but the BinaryReader does not have a ReadLine() function hence the need to implement a ReadLine() on my own.
My current approach reads one character from the stream at a time and fills a StringBuilder until a \r\n is obtained (ignoring all other characters including solitary \r or \n) and then returns a string representation of the StringBuilder (using ToString()).
But I wonder: is this is the most efficient way of implementing the ReadLine() function? Please enlighten me. | 2008/11/21 | [
"https://Stackoverflow.com/questions/308615",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/39648/"
] | You might want to look at using an ODBC/OleDB connection to do this. If you point the data source of an oledb connection to a directory containing csv files, you can then query it as if each CSV was a table.
check http://www.connectionstrings.com/?carrier=textfile>connectionstrings.com for the correct connection string | You could read a bigger chunk at a time, unencode it to a string using Encoder.GetString and then split into lines using string.Split("\r\n") or even picking out the head of the string using string.Substring(0,string.IndexOf("\r\n")) and leaving the rest for processing of the next line. Remember to add the next read operation to your last line from the previous read. |
308,615 | Please feel free to correct me if I am wrong at any point...
I am trying to read a [CSV](http://en.wikipedia.org/wiki/Comma-separated_values) (comma separated values) file using .NET file I/O classes. Now the problem is, this CSV file may contain some fields with soft carriage returns (i.e. solitary \r or \n markers rather than the standard \r\n used in text files to end a line) within some fields and the standard text mode I/O class StreamReader does not respect the standard convention and treats the soft carriage returns as hard carriage returns thus compromising the integrity of the CSV file.
Now using the BinaryReader class seems to be the only option left but the BinaryReader does not have a ReadLine() function hence the need to implement a ReadLine() on my own.
My current approach reads one character from the stream at a time and fills a StringBuilder until a \r\n is obtained (ignoring all other characters including solitary \r or \n) and then returns a string representation of the StringBuilder (using ToString()).
But I wonder: is this is the most efficient way of implementing the ReadLine() function? Please enlighten me. | 2008/11/21 | [
"https://Stackoverflow.com/questions/308615",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/39648/"
] | You might want to look at using an ODBC/OleDB connection to do this. If you point the data source of an oledb connection to a directory containing csv files, you can then query it as if each CSV was a table.
check http://www.connectionstrings.com/?carrier=textfile>connectionstrings.com for the correct connection string | How about simply preprocessing the file?
Replace the soft carriage returns with something unique.
For the record, CSV files with linefeeds in the data, that's bad design. |
308,615 | Please feel free to correct me if I am wrong at any point...
I am trying to read a [CSV](http://en.wikipedia.org/wiki/Comma-separated_values) (comma separated values) file using .NET file I/O classes. Now the problem is, this CSV file may contain some fields with soft carriage returns (i.e. solitary \r or \n markers rather than the standard \r\n used in text files to end a line) within some fields and the standard text mode I/O class StreamReader does not respect the standard convention and treats the soft carriage returns as hard carriage returns thus compromising the integrity of the CSV file.
Now using the BinaryReader class seems to be the only option left but the BinaryReader does not have a ReadLine() function hence the need to implement a ReadLine() on my own.
My current approach reads one character from the stream at a time and fills a StringBuilder until a \r\n is obtained (ignoring all other characters including solitary \r or \n) and then returns a string representation of the StringBuilder (using ToString()).
But I wonder: is this is the most efficient way of implementing the ReadLine() function? Please enlighten me. | 2008/11/21 | [
"https://Stackoverflow.com/questions/308615",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/39648/"
] | You might want to look at using an ODBC/OleDB connection to do this. If you point the data source of an oledb connection to a directory containing csv files, you can then query it as if each CSV was a table.
check http://www.connectionstrings.com/?carrier=textfile>connectionstrings.com for the correct connection string | Your approach sounds fine. One way to improve the efficiency of your method might be to store each line as you're building it in a regular string (i.e. not a StringBuilder), and then append the entire-line-string to your StringBuilder. See [this article](http://www.codeproject.com/KB/cs/StringBuilder_vs_String.aspx) for a further explanation - StringBuilder is not automatically the best choice here.
It probably will matter little, though. |
30,276,399 | How can I make a setting so that I can connect to the server in SQL Server 2008 R2? I mean when my program runs I need to insert first the data source, initial catalog etc. so that I can connect to the server. | 2015/05/16 | [
"https://Stackoverflow.com/questions/30276399",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/4904761/"
] | You need load different text from a database according to users selection (usually stored as session data). For very small list such as menu text, you can store them in your script. | If you just want to change front end text and has no functionality of storing that in database, then i will recommend you to use google translate tool for the websites.
Refer this link for the plugin: <https://translate.google.com/manager/website/>
I hope this helps you. |
30,276,399 | How can I make a setting so that I can connect to the server in SQL Server 2008 R2? I mean when my program runs I need to insert first the data source, initial catalog etc. so that I can connect to the server. | 2015/05/16 | [
"https://Stackoverflow.com/questions/30276399",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/4904761/"
] | If you just want to change front end text and has no functionality of storing that in database, then i will recommend you to use google translate tool for the websites.
Refer this link for the plugin: <https://translate.google.com/manager/website/>
I hope this helps you. | You can use **i18n** to create a multilingual website. To do this follow the link
<http://www.onlinetutz.com/create-a-multilingual-website-using-php-with-i18n/>
it helps you!! |
30,276,399 | How can I make a setting so that I can connect to the server in SQL Server 2008 R2? I mean when my program runs I need to insert first the data source, initial catalog etc. so that I can connect to the server. | 2015/05/16 | [
"https://Stackoverflow.com/questions/30276399",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/4904761/"
] | You need load different text from a database according to users selection (usually stored as session data). For very small list such as menu text, you can store them in your script. | You can use **i18n** to create a multilingual website. To do this follow the link
<http://www.onlinetutz.com/create-a-multilingual-website-using-php-with-i18n/>
it helps you!! |
404,572 | Using my Nikon D5100, shooting RAW pictures and using Darktable to disable absolutely all contrast curves, white balancing, sharpening and even the debayering, I've measured the average value of the green pixels of each picutre in a test (by green pixels I mean the actual physical pixels behind the green filters of the bayer filter, the other pixels where ignored).
This test consisted of, using a constant light (in both intensity and spectrum) and varying the exposure time, find the variation of the average value of the green pixels in respect to the total amount of light in each exposure (as everything else was kept constant, the amount of light integrated in each exposure was directly proportional to the exposure time).
I've got the true exposure times from [this site](https://www.scantips.com/lights/fstop2.htm), which I checked to be exact in the millisecond range with a microphone recording the shutter sound.
Then, I made a graph of the normalized exposure times VS the normalized average green pixel values for those exposure times.
What I expected was to see a 45º straight line, with the values being directly proportional to the amount of light integrated in each exposure.
But instead I got a way different graph:
[](https://i.stack.imgur.com/421vX.png)
This here is quite obviously some particular response function of the CMOS sensor. I didn't find which function makes the best fit on this data yet, logs didn't work very well.
So, what is this response function and why is it like that?
Thanks! | 2018/11/01 | [
"https://electronics.stackexchange.com/questions/404572",
"https://electronics.stackexchange.com",
"https://electronics.stackexchange.com/users/173145/"
] | The LED driver regulates current, so it adjusts the voltage until the current is 20mA.
If you put two LEDs in series, the LED driver will still regulate to 20mA, but the voltage required for that will be the sum of the LED forward voltages.
The downside is that you need a high enough supply voltage, and any channel that has only a single LED will need to drop the voltage in the driver. If it's a buck converter, fine, but a linear regulator will heat up quite a bit. | If you have enough voltage headroom, you should put the LEDs in series, rather than parallel. This way each LED is getting 20mA.
Parallel LEDs, and a resistor in parallel is not a good solution. LEDs are not resistive devices, they behave like diodes where they have a certain voltage drop that doesn't change very much with current.
When you have your LEDs in parallel, tiny differences in their forward voltage drop will cause them to share the current unevenly. This will make their brightness not very uniform. The 100Ω resistors will help with this, though.
Remember, when devices are in series, they have the same current through them. When devices are parallel, the current is different through each branch. |
8,365 | >
> **Possible Duplicate:**
>
> [How to find web hosting that meets my requirements?](https://webmasters.stackexchange.com/questions/20838/how-to-find-web-hosting-that-meets-my-requirements)
>
>
>
My website (a soccer portal, containing Joomla and SMF) in the last months has grown so much that the shared-hosting service I bought about three months ago has decided to rescind our contract and pay the remaining nine months (since the contract is for one-year).
I already searched on the net and on stackexchange too, of course, but I didn't find a solution to this problem.
The website's load is about 280'000-300'000 hits/month.
That's about 10'000 hits/day. This is the main reason they rescinded the contract: we exceeded the number of processes allowed: no other reason exists.
On the web, I read they all say that "if you use a lot of resources, you need a dedicated/virtual server" (something like a VPS).
Ok, so I've searched for a VPS, but I've found they are all too expensive!
The cheapest I've found (on this Q&A board) is Linode, that's about 20$/month.
That could be a very good solution, but I've still some doubts.
My question is: granted that some friends of mine are system analysts, so I wouldn't spend any money to administrate the server, can you suggest the cheapest and most basic hosting/server solution (I mean VPS, dedicated-hosting, shared-hosting, cloud...) for my problem?
As I've already said, our website uses two technologies: Joomla and SMF, so we need the most basic solutions. We don't offer emails to our users, we don't need subdomains, we don't need special technologies as Zope, Tomcat and so on. The most basic: PHP/MySQL. And *if exists* CPanel, just for ease.
Linode is the best I've found, but do other solutions - according to my parameters - exist?
Thank you very much. | 2011/01/27 | [
"https://webmasters.stackexchange.com/questions/8365",
"https://webmasters.stackexchange.com",
"https://webmasters.stackexchange.com/users/4958/"
] | If you are not needing a database, then you can go with Yahoo. I, however, would suggest using godaddy's basic plan. There are some that are cheaper, yes, but what you get with them is the ability to pick up the phone and talk to someone in about 5 minutes. Make sure you get Linux based hosting. | If you are getting 10k hits daily, I have no idea why you can't spend $100 a month for a decent dedicated box. You can easily make 50 times the money of the server by advertising in your site, if you are getting the kind of traffic you are claiming.
Check our hostgator, they are the best in terms of prices and offer the best linux hosting so far in my experience. |
15,918 | Apologies for the word problem. I'm sure there's a simple solution or two, but I'm trying to work out a real world scenario. We used to indoor top rope belay but that was years ago in boy Scouts so our rock climbing knowledge is incomplete and rusty. We've fished this area for years without needing rescue equipment but as everyone gets older and with the level of parkour required to fish this creek, I feel it's time to be more prepared.
Likely scenario: pair of fisherman radio for help with sprained/broken ankle. Unable to follow creek rest of the way to the exit point.
Worst case scenario: single fisherman misses 15 minute radio check-in. Assume unconscious.
Environment: single lane (shared w/ oncoming traffic) mountain road follows creek being fished. Approximately 5 miles between entry/exit points. Road can be as much as 50 feet above creek and incline can be as steep as sheer cliff face though it's usually a sharp incline with near unclimbable shifting gravel. 1 hour drive from cell service, another 1 hour drive to Gunnison hospital.
Rescue team: pickup truck with two adults. We'll drive up till we spot fisherman. Probably anchor to the truck or nearby pine trees, blocking the road for other campers/fisherman. Alternate route for them would be a 5 hour drive around so I believe blocked traffic will wait.
Question: What gear should we prep for potential emergency rescue? I'm assuming this is similar to crevasse rescue without ice picks? | 2017/04/20 | [
"https://outdoors.stackexchange.com/questions/15918",
"https://outdoors.stackexchange.com",
"https://outdoors.stackexchange.com/users/12961/"
] | Unless you are properly trained in rope rescue techniques I would not advise attempting a rescue unless it is pretty clear that the casualty is in immediate danger.
The issue here is that a sprained ankle is not going to immediately kill anyone however a botched attempt to winch them up a cliff very well could. As soon as you start they are in a significantly more dangerous situation than they were at the bottom and if they suddenly deteriorate it is much more difficult to stabilise their condition.
You could also set yourself up for legal liability. If someone is climbing they take responsibility for the fact that they are undertaking a dangerous activity. By contrast in an amateur rescue attempt the casualty may not be in a position to give informed consent for what you are trying to do.
Much better is to make sure you have the equipment to contact the emergency services reliably as well as satellite phones there are various beacon systems designed for exactly this sort of situation. Similarly up to date first aid training and equipment to stabilise a casualty untill help arrives is probably a better investment of effort.
Even if you did get training in rope rescue techniques, unless that is backed up by a degree of experience and regular practice there is a good chance that you will make a dangerous mistake in the heat of the moment.
Probably the worst case is that you have a casualty with a suspected spinal injury (which seems a distinct possibility in the scenario you describe) in which case you don't want to move them at all unless it is to get them out of real imminent danger
It may be that the local fire or ambulance service can give you some more detailed advice which takes into account the facilities available in the area. | The simplest way that I can think of is to have all of the fishermen carry a climbing harness and enough gear that they could ascend the rope. Have two climbing ropes in the truck, one for use and one for backup and if a a fisherman needs help getting up the cliff, anchor the rope, toss the end down to the fisherman and have them pull themselves out.
If they need extra assistance, you can set up a [z-pulley](https://outdoors.stackexchange.com/questions/15585/how-do-you-set-up-a-z-pulley) and help pull them up the cliff.
For your worst case scenario, I would carry a [spinal board](https://en.wikipedia.org/wiki/Spinal_board) in your truck and get the training to use it. |
15,918 | Apologies for the word problem. I'm sure there's a simple solution or two, but I'm trying to work out a real world scenario. We used to indoor top rope belay but that was years ago in boy Scouts so our rock climbing knowledge is incomplete and rusty. We've fished this area for years without needing rescue equipment but as everyone gets older and with the level of parkour required to fish this creek, I feel it's time to be more prepared.
Likely scenario: pair of fisherman radio for help with sprained/broken ankle. Unable to follow creek rest of the way to the exit point.
Worst case scenario: single fisherman misses 15 minute radio check-in. Assume unconscious.
Environment: single lane (shared w/ oncoming traffic) mountain road follows creek being fished. Approximately 5 miles between entry/exit points. Road can be as much as 50 feet above creek and incline can be as steep as sheer cliff face though it's usually a sharp incline with near unclimbable shifting gravel. 1 hour drive from cell service, another 1 hour drive to Gunnison hospital.
Rescue team: pickup truck with two adults. We'll drive up till we spot fisherman. Probably anchor to the truck or nearby pine trees, blocking the road for other campers/fisherman. Alternate route for them would be a 5 hour drive around so I believe blocked traffic will wait.
Question: What gear should we prep for potential emergency rescue? I'm assuming this is similar to crevasse rescue without ice picks? | 2017/04/20 | [
"https://outdoors.stackexchange.com/questions/15918",
"https://outdoors.stackexchange.com",
"https://outdoors.stackexchange.com/users/12961/"
] | Don't
-----
Given your description and your background: Don't even try it!
Hauling any load up a slope is much harder than up a vertical cliff, and to attempt that with an injured person... just don't! You'll only end up wasting precious time and quite possibly harm the victim even more.
In your scenario, I'd drive that hour for cell reception rather than attempt to set uo a hauling system, and I *know* how to do it.
If you feel the extra security is needed, get a sat phone, PLB, VHF radio or whatever works and is available/affordable. | The simplest way that I can think of is to have all of the fishermen carry a climbing harness and enough gear that they could ascend the rope. Have two climbing ropes in the truck, one for use and one for backup and if a a fisherman needs help getting up the cliff, anchor the rope, toss the end down to the fisherman and have them pull themselves out.
If they need extra assistance, you can set up a [z-pulley](https://outdoors.stackexchange.com/questions/15585/how-do-you-set-up-a-z-pulley) and help pull them up the cliff.
For your worst case scenario, I would carry a [spinal board](https://en.wikipedia.org/wiki/Spinal_board) in your truck and get the training to use it. |
15,918 | Apologies for the word problem. I'm sure there's a simple solution or two, but I'm trying to work out a real world scenario. We used to indoor top rope belay but that was years ago in boy Scouts so our rock climbing knowledge is incomplete and rusty. We've fished this area for years without needing rescue equipment but as everyone gets older and with the level of parkour required to fish this creek, I feel it's time to be more prepared.
Likely scenario: pair of fisherman radio for help with sprained/broken ankle. Unable to follow creek rest of the way to the exit point.
Worst case scenario: single fisherman misses 15 minute radio check-in. Assume unconscious.
Environment: single lane (shared w/ oncoming traffic) mountain road follows creek being fished. Approximately 5 miles between entry/exit points. Road can be as much as 50 feet above creek and incline can be as steep as sheer cliff face though it's usually a sharp incline with near unclimbable shifting gravel. 1 hour drive from cell service, another 1 hour drive to Gunnison hospital.
Rescue team: pickup truck with two adults. We'll drive up till we spot fisherman. Probably anchor to the truck or nearby pine trees, blocking the road for other campers/fisherman. Alternate route for them would be a 5 hour drive around so I believe blocked traffic will wait.
Question: What gear should we prep for potential emergency rescue? I'm assuming this is similar to crevasse rescue without ice picks? | 2017/04/20 | [
"https://outdoors.stackexchange.com/questions/15918",
"https://outdoors.stackexchange.com",
"https://outdoors.stackexchange.com/users/12961/"
] | Unless you are properly trained in rope rescue techniques I would not advise attempting a rescue unless it is pretty clear that the casualty is in immediate danger.
The issue here is that a sprained ankle is not going to immediately kill anyone however a botched attempt to winch them up a cliff very well could. As soon as you start they are in a significantly more dangerous situation than they were at the bottom and if they suddenly deteriorate it is much more difficult to stabilise their condition.
You could also set yourself up for legal liability. If someone is climbing they take responsibility for the fact that they are undertaking a dangerous activity. By contrast in an amateur rescue attempt the casualty may not be in a position to give informed consent for what you are trying to do.
Much better is to make sure you have the equipment to contact the emergency services reliably as well as satellite phones there are various beacon systems designed for exactly this sort of situation. Similarly up to date first aid training and equipment to stabilise a casualty untill help arrives is probably a better investment of effort.
Even if you did get training in rope rescue techniques, unless that is backed up by a degree of experience and regular practice there is a good chance that you will make a dangerous mistake in the heat of the moment.
Probably the worst case is that you have a casualty with a suspected spinal injury (which seems a distinct possibility in the scenario you describe) in which case you don't want to move them at all unless it is to get them out of real imminent danger
It may be that the local fire or ambulance service can give you some more detailed advice which takes into account the facilities available in the area. | It is good that you are planning ahead. Assuming no communications, and recovery with your group and available assets is the best choice.
Beyond basic first aid, you need a couple of things.
* [Rescue sled (random web link)](http://www.landfallnavigation.com/mp.html?cmp=froogle&kw=mp&utm_source=mp&utm_medium=shopping%2Bengine&utm_campaign=froogle&gclid=Cj0KEQjw2-bHBRDEh6qk5b6yqKIBEiQAFUz29qeM7VLJ_VjM89zrPoplfs4xQdKL_kMtIgkh7qI2hfgaAnpY8P8HAQ) these run about $1,000 (US)
* A winch rated for human lifting, there are several considerations here. While a standard vehicle or manually operated winch has potential you should understand the risks before betting someones life on one.
* Safety equipment for rescue personal.
* Training, you will need to be trained and gain some experience in the types of rescues you are anticipating. People die and/or kill their friends, when they make poor choices trying to save them. You need to **"KNOW"** how and what to do.
The most important thing above is training and experience. The best place to get that is volunteering with your local fire department or rescue organization. You don't say where you live, but if you are rural enough to go fishing, where the bypass road is a 5 hour trip, you should be rural enough that the majority of fire/rescue has available volunteer positions that will get you the training and experience you need to keep yourself and your friends alive when an emergency occurs. |
15,918 | Apologies for the word problem. I'm sure there's a simple solution or two, but I'm trying to work out a real world scenario. We used to indoor top rope belay but that was years ago in boy Scouts so our rock climbing knowledge is incomplete and rusty. We've fished this area for years without needing rescue equipment but as everyone gets older and with the level of parkour required to fish this creek, I feel it's time to be more prepared.
Likely scenario: pair of fisherman radio for help with sprained/broken ankle. Unable to follow creek rest of the way to the exit point.
Worst case scenario: single fisherman misses 15 minute radio check-in. Assume unconscious.
Environment: single lane (shared w/ oncoming traffic) mountain road follows creek being fished. Approximately 5 miles between entry/exit points. Road can be as much as 50 feet above creek and incline can be as steep as sheer cliff face though it's usually a sharp incline with near unclimbable shifting gravel. 1 hour drive from cell service, another 1 hour drive to Gunnison hospital.
Rescue team: pickup truck with two adults. We'll drive up till we spot fisherman. Probably anchor to the truck or nearby pine trees, blocking the road for other campers/fisherman. Alternate route for them would be a 5 hour drive around so I believe blocked traffic will wait.
Question: What gear should we prep for potential emergency rescue? I'm assuming this is similar to crevasse rescue without ice picks? | 2017/04/20 | [
"https://outdoors.stackexchange.com/questions/15918",
"https://outdoors.stackexchange.com",
"https://outdoors.stackexchange.com/users/12961/"
] | Unless you are properly trained in rope rescue techniques I would not advise attempting a rescue unless it is pretty clear that the casualty is in immediate danger.
The issue here is that a sprained ankle is not going to immediately kill anyone however a botched attempt to winch them up a cliff very well could. As soon as you start they are in a significantly more dangerous situation than they were at the bottom and if they suddenly deteriorate it is much more difficult to stabilise their condition.
You could also set yourself up for legal liability. If someone is climbing they take responsibility for the fact that they are undertaking a dangerous activity. By contrast in an amateur rescue attempt the casualty may not be in a position to give informed consent for what you are trying to do.
Much better is to make sure you have the equipment to contact the emergency services reliably as well as satellite phones there are various beacon systems designed for exactly this sort of situation. Similarly up to date first aid training and equipment to stabilise a casualty untill help arrives is probably a better investment of effort.
Even if you did get training in rope rescue techniques, unless that is backed up by a degree of experience and regular practice there is a good chance that you will make a dangerous mistake in the heat of the moment.
Probably the worst case is that you have a casualty with a suspected spinal injury (which seems a distinct possibility in the scenario you describe) in which case you don't want to move them at all unless it is to get them out of real imminent danger
It may be that the local fire or ambulance service can give you some more detailed advice which takes into account the facilities available in the area. | It sounds like this would fall under the category of high angle rescue. This is not something that you want to get into. It sounds like you would be at most 2.5 miles from the an easy extraction point. Faced with a vertical haul on a 50' cliff with lose gravel and a 2.5 mile carry, most rescuers will opt for the carry.
The first piece of gear you need is a sat phone or some sort of emergency PLB to call for help. This will reduce the rescue time by at least 1 hour. You will also want a spotting scope and megaphone to help you communicate with the injured individual and assess the situation. You will want a medium size first aid kit, some food and water, extra clothes, a shelter, and a pair of high quality walkie talkies in a backpack in the truck.
If you are willing to undergo some training, a static line, harness, and some gear to set an anchor, on trees, rocks, or possibly the truck, to enable one of you to rappel down to the injured individual would not be unreasonable. Remember to do this far enough downstream to prevent knocking rocks onto the person below.
When you get to the scene you need to assess the situation for severity and your ability to get to the person. You need to determine if you can safely walk to their location (possibly by driving the 2.5 miles) or, if you have the training, if you can rappel to them. You will want to make sure your rescue kit has everything you need to spend the night in the stream. |
15,918 | Apologies for the word problem. I'm sure there's a simple solution or two, but I'm trying to work out a real world scenario. We used to indoor top rope belay but that was years ago in boy Scouts so our rock climbing knowledge is incomplete and rusty. We've fished this area for years without needing rescue equipment but as everyone gets older and with the level of parkour required to fish this creek, I feel it's time to be more prepared.
Likely scenario: pair of fisherman radio for help with sprained/broken ankle. Unable to follow creek rest of the way to the exit point.
Worst case scenario: single fisherman misses 15 minute radio check-in. Assume unconscious.
Environment: single lane (shared w/ oncoming traffic) mountain road follows creek being fished. Approximately 5 miles between entry/exit points. Road can be as much as 50 feet above creek and incline can be as steep as sheer cliff face though it's usually a sharp incline with near unclimbable shifting gravel. 1 hour drive from cell service, another 1 hour drive to Gunnison hospital.
Rescue team: pickup truck with two adults. We'll drive up till we spot fisherman. Probably anchor to the truck or nearby pine trees, blocking the road for other campers/fisherman. Alternate route for them would be a 5 hour drive around so I believe blocked traffic will wait.
Question: What gear should we prep for potential emergency rescue? I'm assuming this is similar to crevasse rescue without ice picks? | 2017/04/20 | [
"https://outdoors.stackexchange.com/questions/15918",
"https://outdoors.stackexchange.com",
"https://outdoors.stackexchange.com/users/12961/"
] | Unless you are properly trained in rope rescue techniques I would not advise attempting a rescue unless it is pretty clear that the casualty is in immediate danger.
The issue here is that a sprained ankle is not going to immediately kill anyone however a botched attempt to winch them up a cliff very well could. As soon as you start they are in a significantly more dangerous situation than they were at the bottom and if they suddenly deteriorate it is much more difficult to stabilise their condition.
You could also set yourself up for legal liability. If someone is climbing they take responsibility for the fact that they are undertaking a dangerous activity. By contrast in an amateur rescue attempt the casualty may not be in a position to give informed consent for what you are trying to do.
Much better is to make sure you have the equipment to contact the emergency services reliably as well as satellite phones there are various beacon systems designed for exactly this sort of situation. Similarly up to date first aid training and equipment to stabilise a casualty untill help arrives is probably a better investment of effort.
Even if you did get training in rope rescue techniques, unless that is backed up by a degree of experience and regular practice there is a good chance that you will make a dangerous mistake in the heat of the moment.
Probably the worst case is that you have a casualty with a suspected spinal injury (which seems a distinct possibility in the scenario you describe) in which case you don't want to move them at all unless it is to get them out of real imminent danger
It may be that the local fire or ambulance service can give you some more detailed advice which takes into account the facilities available in the area. | Your rescue team of "2 guys and a pickup" is insufficient, the minimum trained people we would attempt this rescue with [we have done more then one of these] would be 8, 12+ would be better.
First off, like someone suggested, a reasonably safe stretcher carry is preferred over high angle. Presuming our fishermen are built like most fishermen, carrying one for more than 10 minutes is going to be a chore. generally 6 people required to carry a stretcher, unless terrain forces less, and those 6, unless there big guys in tip top shape [think on the better side of young firefighters], will need to switch off the stretcher every 6 minuets or so. 2.5 miles is going to take forever on a rough trail, think 4-10 hours. additionally if there is no trail along the one side of the river, you now half-to consider taking someone who is totally immobilized, over water, were worse came to worse you could drown them. this may not be your best option.
As for going strait over the cliff, what you describe is High angle rescue. Our protocols require a 2 rope system [**NEVER WINCH PEOPLE!!!!!** if they get caught on a snag you could pull the rope, harness or the person apart before you noticed.] A well practiced rope team can do a top down rescue like this in less than 25 minutes, If you barely remember your knots, and don't know what a rope system means, I wouldn't even try. Seriously if you drop someone 40 feet down a scree slope they will be in much worse shape than a night with a broken ankle.
The advice of carrying a satellite beacon is a good one, get one with 2 way communication [inreach/spot connect], Carry a suitable first aid kit, flashlights [rescue may take a few hours], insulation/dry clothing [in a waterproof container ie. drybag], if an ankle injury is what your expecting carry an ankle splint, [sam splint, a self inflating mattress like a thermarest is both thermal protection, and a great improvised splint. Take a wilderness First Aid course, make sure your friends take one [keep in mind, there the ones who will be treating you.
If your dead set on the rescue side, the most technical thing I would consider, would be a simple repel off the road, as suggested by strong bad, but even then, you should understand what your doing, be well practiced, and carry self rescue equipment [rope asenders etc.]
edit, it may be relevant that most jurisdictions will *NEVER charge for rescue*, it is always easier to do a quick call that may not have been totally necessary, than arrive in the middle of the night when it has devolved into an emergency. |
15,918 | Apologies for the word problem. I'm sure there's a simple solution or two, but I'm trying to work out a real world scenario. We used to indoor top rope belay but that was years ago in boy Scouts so our rock climbing knowledge is incomplete and rusty. We've fished this area for years without needing rescue equipment but as everyone gets older and with the level of parkour required to fish this creek, I feel it's time to be more prepared.
Likely scenario: pair of fisherman radio for help with sprained/broken ankle. Unable to follow creek rest of the way to the exit point.
Worst case scenario: single fisherman misses 15 minute radio check-in. Assume unconscious.
Environment: single lane (shared w/ oncoming traffic) mountain road follows creek being fished. Approximately 5 miles between entry/exit points. Road can be as much as 50 feet above creek and incline can be as steep as sheer cliff face though it's usually a sharp incline with near unclimbable shifting gravel. 1 hour drive from cell service, another 1 hour drive to Gunnison hospital.
Rescue team: pickup truck with two adults. We'll drive up till we spot fisherman. Probably anchor to the truck or nearby pine trees, blocking the road for other campers/fisherman. Alternate route for them would be a 5 hour drive around so I believe blocked traffic will wait.
Question: What gear should we prep for potential emergency rescue? I'm assuming this is similar to crevasse rescue without ice picks? | 2017/04/20 | [
"https://outdoors.stackexchange.com/questions/15918",
"https://outdoors.stackexchange.com",
"https://outdoors.stackexchange.com/users/12961/"
] | Don't
-----
Given your description and your background: Don't even try it!
Hauling any load up a slope is much harder than up a vertical cliff, and to attempt that with an injured person... just don't! You'll only end up wasting precious time and quite possibly harm the victim even more.
In your scenario, I'd drive that hour for cell reception rather than attempt to set uo a hauling system, and I *know* how to do it.
If you feel the extra security is needed, get a sat phone, PLB, VHF radio or whatever works and is available/affordable. | It is good that you are planning ahead. Assuming no communications, and recovery with your group and available assets is the best choice.
Beyond basic first aid, you need a couple of things.
* [Rescue sled (random web link)](http://www.landfallnavigation.com/mp.html?cmp=froogle&kw=mp&utm_source=mp&utm_medium=shopping%2Bengine&utm_campaign=froogle&gclid=Cj0KEQjw2-bHBRDEh6qk5b6yqKIBEiQAFUz29qeM7VLJ_VjM89zrPoplfs4xQdKL_kMtIgkh7qI2hfgaAnpY8P8HAQ) these run about $1,000 (US)
* A winch rated for human lifting, there are several considerations here. While a standard vehicle or manually operated winch has potential you should understand the risks before betting someones life on one.
* Safety equipment for rescue personal.
* Training, you will need to be trained and gain some experience in the types of rescues you are anticipating. People die and/or kill their friends, when they make poor choices trying to save them. You need to **"KNOW"** how and what to do.
The most important thing above is training and experience. The best place to get that is volunteering with your local fire department or rescue organization. You don't say where you live, but if you are rural enough to go fishing, where the bypass road is a 5 hour trip, you should be rural enough that the majority of fire/rescue has available volunteer positions that will get you the training and experience you need to keep yourself and your friends alive when an emergency occurs. |
15,918 | Apologies for the word problem. I'm sure there's a simple solution or two, but I'm trying to work out a real world scenario. We used to indoor top rope belay but that was years ago in boy Scouts so our rock climbing knowledge is incomplete and rusty. We've fished this area for years without needing rescue equipment but as everyone gets older and with the level of parkour required to fish this creek, I feel it's time to be more prepared.
Likely scenario: pair of fisherman radio for help with sprained/broken ankle. Unable to follow creek rest of the way to the exit point.
Worst case scenario: single fisherman misses 15 minute radio check-in. Assume unconscious.
Environment: single lane (shared w/ oncoming traffic) mountain road follows creek being fished. Approximately 5 miles between entry/exit points. Road can be as much as 50 feet above creek and incline can be as steep as sheer cliff face though it's usually a sharp incline with near unclimbable shifting gravel. 1 hour drive from cell service, another 1 hour drive to Gunnison hospital.
Rescue team: pickup truck with two adults. We'll drive up till we spot fisherman. Probably anchor to the truck or nearby pine trees, blocking the road for other campers/fisherman. Alternate route for them would be a 5 hour drive around so I believe blocked traffic will wait.
Question: What gear should we prep for potential emergency rescue? I'm assuming this is similar to crevasse rescue without ice picks? | 2017/04/20 | [
"https://outdoors.stackexchange.com/questions/15918",
"https://outdoors.stackexchange.com",
"https://outdoors.stackexchange.com/users/12961/"
] | Don't
-----
Given your description and your background: Don't even try it!
Hauling any load up a slope is much harder than up a vertical cliff, and to attempt that with an injured person... just don't! You'll only end up wasting precious time and quite possibly harm the victim even more.
In your scenario, I'd drive that hour for cell reception rather than attempt to set uo a hauling system, and I *know* how to do it.
If you feel the extra security is needed, get a sat phone, PLB, VHF radio or whatever works and is available/affordable. | It sounds like this would fall under the category of high angle rescue. This is not something that you want to get into. It sounds like you would be at most 2.5 miles from the an easy extraction point. Faced with a vertical haul on a 50' cliff with lose gravel and a 2.5 mile carry, most rescuers will opt for the carry.
The first piece of gear you need is a sat phone or some sort of emergency PLB to call for help. This will reduce the rescue time by at least 1 hour. You will also want a spotting scope and megaphone to help you communicate with the injured individual and assess the situation. You will want a medium size first aid kit, some food and water, extra clothes, a shelter, and a pair of high quality walkie talkies in a backpack in the truck.
If you are willing to undergo some training, a static line, harness, and some gear to set an anchor, on trees, rocks, or possibly the truck, to enable one of you to rappel down to the injured individual would not be unreasonable. Remember to do this far enough downstream to prevent knocking rocks onto the person below.
When you get to the scene you need to assess the situation for severity and your ability to get to the person. You need to determine if you can safely walk to their location (possibly by driving the 2.5 miles) or, if you have the training, if you can rappel to them. You will want to make sure your rescue kit has everything you need to spend the night in the stream. |
15,918 | Apologies for the word problem. I'm sure there's a simple solution or two, but I'm trying to work out a real world scenario. We used to indoor top rope belay but that was years ago in boy Scouts so our rock climbing knowledge is incomplete and rusty. We've fished this area for years without needing rescue equipment but as everyone gets older and with the level of parkour required to fish this creek, I feel it's time to be more prepared.
Likely scenario: pair of fisherman radio for help with sprained/broken ankle. Unable to follow creek rest of the way to the exit point.
Worst case scenario: single fisherman misses 15 minute radio check-in. Assume unconscious.
Environment: single lane (shared w/ oncoming traffic) mountain road follows creek being fished. Approximately 5 miles between entry/exit points. Road can be as much as 50 feet above creek and incline can be as steep as sheer cliff face though it's usually a sharp incline with near unclimbable shifting gravel. 1 hour drive from cell service, another 1 hour drive to Gunnison hospital.
Rescue team: pickup truck with two adults. We'll drive up till we spot fisherman. Probably anchor to the truck or nearby pine trees, blocking the road for other campers/fisherman. Alternate route for them would be a 5 hour drive around so I believe blocked traffic will wait.
Question: What gear should we prep for potential emergency rescue? I'm assuming this is similar to crevasse rescue without ice picks? | 2017/04/20 | [
"https://outdoors.stackexchange.com/questions/15918",
"https://outdoors.stackexchange.com",
"https://outdoors.stackexchange.com/users/12961/"
] | Don't
-----
Given your description and your background: Don't even try it!
Hauling any load up a slope is much harder than up a vertical cliff, and to attempt that with an injured person... just don't! You'll only end up wasting precious time and quite possibly harm the victim even more.
In your scenario, I'd drive that hour for cell reception rather than attempt to set uo a hauling system, and I *know* how to do it.
If you feel the extra security is needed, get a sat phone, PLB, VHF radio or whatever works and is available/affordable. | Your rescue team of "2 guys and a pickup" is insufficient, the minimum trained people we would attempt this rescue with [we have done more then one of these] would be 8, 12+ would be better.
First off, like someone suggested, a reasonably safe stretcher carry is preferred over high angle. Presuming our fishermen are built like most fishermen, carrying one for more than 10 minutes is going to be a chore. generally 6 people required to carry a stretcher, unless terrain forces less, and those 6, unless there big guys in tip top shape [think on the better side of young firefighters], will need to switch off the stretcher every 6 minuets or so. 2.5 miles is going to take forever on a rough trail, think 4-10 hours. additionally if there is no trail along the one side of the river, you now half-to consider taking someone who is totally immobilized, over water, were worse came to worse you could drown them. this may not be your best option.
As for going strait over the cliff, what you describe is High angle rescue. Our protocols require a 2 rope system [**NEVER WINCH PEOPLE!!!!!** if they get caught on a snag you could pull the rope, harness or the person apart before you noticed.] A well practiced rope team can do a top down rescue like this in less than 25 minutes, If you barely remember your knots, and don't know what a rope system means, I wouldn't even try. Seriously if you drop someone 40 feet down a scree slope they will be in much worse shape than a night with a broken ankle.
The advice of carrying a satellite beacon is a good one, get one with 2 way communication [inreach/spot connect], Carry a suitable first aid kit, flashlights [rescue may take a few hours], insulation/dry clothing [in a waterproof container ie. drybag], if an ankle injury is what your expecting carry an ankle splint, [sam splint, a self inflating mattress like a thermarest is both thermal protection, and a great improvised splint. Take a wilderness First Aid course, make sure your friends take one [keep in mind, there the ones who will be treating you.
If your dead set on the rescue side, the most technical thing I would consider, would be a simple repel off the road, as suggested by strong bad, but even then, you should understand what your doing, be well practiced, and carry self rescue equipment [rope asenders etc.]
edit, it may be relevant that most jurisdictions will *NEVER charge for rescue*, it is always easier to do a quick call that may not have been totally necessary, than arrive in the middle of the night when it has devolved into an emergency. |
39,127 | I have been running on a treadmill regularly as part of my gym routine for the past two years. Over the last six months or so, I have been regularly doing 5 Km in 30 mins twice a week in addition to shorter 20 minute runs for a total of four to five days a week.
I want to start running marathons, and was wondering whether my regime would have me prepared for a 10 Km run as a first marathon.
The marathon I am talking about is taking place next week. | 2018/11/16 | [
"https://fitness.stackexchange.com/questions/39127",
"https://fitness.stackexchange.com",
"https://fitness.stackexchange.com/users/29899/"
] | I'm being a bit (very?) anal here, but it's a 10k not a marathon nor is it a quarter marathon.
In any case, a week is a very short time to get ready!
You need to start running outside on the real road or trails. This is because treadmills don't work on all the same muscles as the real road. The machine maintains in a way pushes you at all times so you can push off the belt and there is a "give" vs on the road where the ground does not "give" on every step. As well the machine maintains a constant mechanical pace vs road running where you need to mentally maintain it.
You may notice this the first time you run and feel gassed and a bit achy in certain parts of your legs. So, start off easy because you may not be able to hit the same pace as on the treadmill, at least initially.
Overdoing it so soon could make you hurt too much on the actual run day.
Another piece is the fact that you have never run a continuous 10k. This means pacing is going to be very different. You cannot run 10k at the same pace as a 5k as you will wear down very quickly. Example if you do 5k in 30 minutes, you won't likely do 10k in 1 hour. Pace yourself to take longer, perhaps 1:15 to 1:30. Further in as you go through the run you can mentally reevaluate your condition and adjust your speed. It's better in this reduced training time to save a little gas for later.
One more thing is psychology/discipline. These runs have a lot of people usually, so keeping your pace and focus is very important. Don't get psyched into trying to catch up to someone running faster than you as they could have a different game plan and conditioning. Plan and keep a straight course to minimize waste of energy trying to dodge people and any obstacles | Depends on the training on the treadmill. Do you do intervalls? How do you feel after 30min? Is 5k your physical maximum? What is your FTP?
Also depends on the course of the race. Is it flat? Best Option for a fist try would be something like a stadium racetrack due to the similarities with a treadmill run. Defenetly don´t go for a challenging course like cross country. You could risk injury due to uneven ground which you are not used to |
161,854 | While I am looking for some nice roads in Spain for my next roadtrip, I noticed that the roads there have different numbera A-, B-, N- etc, some of them have even a letter at the end (C-1412a)
What is the meaning of all those letters and numbers? Does a bigger number mean a smaller road?
[](https://i.stack.imgur.com/wsqV8.jpg) | 2020/12/30 | [
"https://travel.stackexchange.com/questions/161854",
"https://travel.stackexchange.com",
"https://travel.stackexchange.com/users/2560/"
] | The letter determines the ambit of the road. The number is the identifier. Basically [the main roads we have are](https://www.cnae.com/blog/index.php/clasificacion-carreteras-tipos-espana/) (ESP):
* A / AP: Highways
* N: National roads
* Autonomic roads
These are ordered from better to worst, but there are exceptions (i.e. you can find a new secondary road that has better pavement than a nearby national road). Anyway, in general, the roads in Spain are quite good and relatively free compared to other European countries.
Some considerations:
* A/AP highways are two types of roads that are equivalent and represent the better/faster roads you can find. The difference used to be that the A were free but you have to pay for the AP. Nowadays you can find a lot of AP for free (check on Google Maps or similar, they know which are free).
* N roads and A/AP highways sometimes share the code with E that represents European roads. Forget about E because doesn't exist pure E roads in Spain, all share code with Spanish roads and always the Spanish code is put before and bolder.
* As you may know in Spain we have 17 different regions and each one is in charge of part of the roads. These roads that usually connect internally the region are called "*Carreteras Autonómicas*" and are represented by one or two letters taken from the [name of the autonomy](https://es.wikipedia.org/wiki/Anexo:Red_Auton%C3%B3mica_de_carreteras_de_Espa%C3%B1a). For example, in Comunidad Valenciana you have CV-*XXX* or in Madrid you have CM-*XXX*. Each region is divided in "*Provincias*" and each of these has also a road network that uses one or two letters from the name of the *Provincia*. In Almeria, for example you will see AL-*XXX* roads. In the wikipedia link provided you can find all the letters used, but really, don't bother about it: these roads are usually a surprise, sometimes are better than N roads and sometimes are bumpy and dusty roads.
* You also can find some special roads like M-30, M-40, etc. that are like highways but local used to encircle big cities (M i.e. is for Madrid, but you have also in Sevilla or Barcelona).
* When a road has a sufix like N-343a these letter is a variant for that road. So, the road goes to the same place but you'll go through different routes (normally you will connect with the same road in a few kilometers).
* As rule of thumb, the bigger numbers represent lower levels in the same level. So A-7 is a very nice road and A-77 is secondary to that.
* In all A/AP roads you can reach 120Km/h in general while in the rest of the roads the maximum allowed speed by default is 90km/h, except if they are inside a town or city and then the default maximum is 50km/h.
In general, if you are finding good/fast roads try to take the A/AP network. If you are looking for scenic go to the autonomic roads, specially those that appears white in Google Maps. | | Road class | [Syntax explanation](https://sites.google.com/site/roadnumberingsystems/home/general-information/legend) |
| --- | --- |
| European road | E-[0-9]<2-3> |
| Motorway (Autopista) | AP-[0-9]<1-2> |
| Expressway (Autovía) | A-[0-9]<1-2> |
| Radial motorway | R[1-5] |
| National road (Carretera Nacional) | N-`Roman`{a};N-[0-9]<3>{a} |
| Regional road (Carretera Comarcal) | C-[0-9]<3-4>{a} |
| Community road | [see region table](https://sites.google.com/site/roadnumberingsystems/home/countries/spain#eregions) |
The table comes from [roadnumberingsystems](https://sites.google.com/site/roadnumberingsystems/home/countries/spain#eregions) ([mirror](https://web.archive.org/web/20201230001320/https://sites.google.com/site/roadnumberingsystems/home/countries/spain#eregions)), which gives a more thorough explanation:
[](https://i.stack.imgur.com/66lsf.png) |
14,438 | Are there any front-running approaches to using server-generated hashes to encapsulate patient condition in a concise manner while maximizing security?
For example, a system to represent current med profile in a hash that can be used to check for contraindications without revealing the specific component prescriptions? | 2011/10/13 | [
"https://security.stackexchange.com/questions/14438",
"https://security.stackexchange.com",
"https://security.stackexchange.com/users/-1/"
] | None that I know of. And I believe this is because.. I don't think the solution (implied by the question) is a good solution/proposal.
Not only because hashing function may have collisions (even if it has a very low probability, the impact would be major, so why should we add such a risk ?) but also because you have another problem prior to hashing: unless you solve something that has not yet been fully solved (i.e. **semantic interoperability**), in a med profile you can -for instance- find/formulate the very same medical concept in several different ways (i.e. different text sequences may mean the same thing/medical concept) so in those cases you would get different hashes referring to the same concept (!) . How would you manage that ? Will you be able to map all those different hashes to the same medical concept ? (type of allergy or whatever). How would you say that two hashes really mean two different things.. and which things should they be ?. I believe you won't be able to predict all the possible different ways in our language we could express the same concept and the resulting hashing values will be severely flowed in semantic terms.
Even if you choose to use the best terminologies and controlled vocabularies or coded information to be used in the med profile, they will still need continued maintenance and revision over time (because of versioning etc. e.g. aliases, new concept in, deprecated concepts out etc.) all things that will impact severly on the effectiveness and reliability of your "decision support system" based on concepts hided by hashes values. So I don't think it is a good idea to hide a medical concept behind hashes and taking decisions based only on the hashes values.
Besides, if I authorize my Doctor to access my medical record, I want him to see it very clearly what my allergy is in terms he can understand. Can you imagine your Doctor watching hashing values supposed to be mapped vs. some medical coded information having absolutely no way to really verify the real concept that may be behind ? Not a good idea. You want compression ? Use compression algorythms. You want security ? User encryption with two ways functions and authentication infrastructure etc. (keep in mind that hashing is a "one-way" function). Just keep using hashing for those things we use them today (to index, retrieve items more efficiently, for digital signatures etc.) NOT to hide/store medical concepts. I would not innovate this way. But may be I am wrong. Is there a better answer to this? | Hashing would not be very practical in this case. Not because of collisions, since a good cryptographically secure hash (e.g. [SHA-2](http://en.wikipedia.org/wiki/SHA-2)) won't have any collisions that can occur in the wild with any reasonable probability. The problem is that hashes are one-way, so in order to deduce your conditions all possible combinations must be hashed and compared to *your* hash.
A more interesting approach would be to use [homomorphic crypto](http://en.wikipedia.org/wiki/Homomorphic_encryption). Homomorphic crypto allows you to make some classes of computations on encrypted data, e.g. computing averages and similar. Microsoft Research has developed a very promising approach in [this paper](http://research.microsoft.com/pubs/148825/ccs2011_submission_412.pdf) by . |
14,438 | Are there any front-running approaches to using server-generated hashes to encapsulate patient condition in a concise manner while maximizing security?
For example, a system to represent current med profile in a hash that can be used to check for contraindications without revealing the specific component prescriptions? | 2011/10/13 | [
"https://security.stackexchange.com/questions/14438",
"https://security.stackexchange.com",
"https://security.stackexchange.com/users/-1/"
] | None that I know of. And I believe this is because.. I don't think the solution (implied by the question) is a good solution/proposal.
Not only because hashing function may have collisions (even if it has a very low probability, the impact would be major, so why should we add such a risk ?) but also because you have another problem prior to hashing: unless you solve something that has not yet been fully solved (i.e. **semantic interoperability**), in a med profile you can -for instance- find/formulate the very same medical concept in several different ways (i.e. different text sequences may mean the same thing/medical concept) so in those cases you would get different hashes referring to the same concept (!) . How would you manage that ? Will you be able to map all those different hashes to the same medical concept ? (type of allergy or whatever). How would you say that two hashes really mean two different things.. and which things should they be ?. I believe you won't be able to predict all the possible different ways in our language we could express the same concept and the resulting hashing values will be severely flowed in semantic terms.
Even if you choose to use the best terminologies and controlled vocabularies or coded information to be used in the med profile, they will still need continued maintenance and revision over time (because of versioning etc. e.g. aliases, new concept in, deprecated concepts out etc.) all things that will impact severly on the effectiveness and reliability of your "decision support system" based on concepts hided by hashes values. So I don't think it is a good idea to hide a medical concept behind hashes and taking decisions based only on the hashes values.
Besides, if I authorize my Doctor to access my medical record, I want him to see it very clearly what my allergy is in terms he can understand. Can you imagine your Doctor watching hashing values supposed to be mapped vs. some medical coded information having absolutely no way to really verify the real concept that may be behind ? Not a good idea. You want compression ? Use compression algorythms. You want security ? User encryption with two ways functions and authentication infrastructure etc. (keep in mind that hashing is a "one-way" function). Just keep using hashing for those things we use them today (to index, retrieve items more efficiently, for digital signatures etc.) NOT to hide/store medical concepts. I would not innovate this way. But may be I am wrong. Is there a better answer to this? | There is a fundamental flaw in the kind of setup you suggest, which is that it is intrinsically vulnerable to *informed guesswork*. By sending targeted requests, it would be possible to narrow down the number of possible conditions quite quickly; this is the very same process that lies behind medical diagnosis itself.
There is an active research area about working with encrypted databases, such that you can obtain some partial information on the data without being able to decrypt it. However, partial information can be very revealing. For instance, if you have an encrypted number *x* and can ask questions such as "is *x* greater than 1000 ?" then a [dichotomic search](http://en.wikipedia.org/wiki/Dichotomic_search) will reveal *x* with a high precision within a few dozen requests.
This means that the security model which is envisioned here (the *physician* is the potential attacker) is a rather hopeless setup. (Also, it makes relatively little practical sense: physicians need to know all of the medical history of their patients in order to do their work properly.)
A *distinct* model is what [homomorphic encryption](http://en.wikipedia.org/wiki/Homomorphic_encryption) is about: the ability to compute things over encrypted data, such that you get an *encrypted* result. This is useful to offload the most of the computation work to a powerful but untrusted system. But whoever can obtain the *decrypted* result has the power to decrypt all the stored data, by construction; so this is not the same model. |
524,305 | We know that electrons have a dual nature just like EM waves (of course all the materials are said to have dual nature, noticeable or not). So looking at the wave nature of an electron and comparing this with photons, is it possible to make its kinetic energy equal to zero?
Copied form researchgate... | 2020/01/11 | [
"https://physics.stackexchange.com/questions/524305",
"https://physics.stackexchange.com",
"https://physics.stackexchange.com/users/249494/"
] | First of all, you can't compare photons with electrons. They are different types of particles (spin 1 vs spin1/2; force transmitter vs force emitter; see [this](https://physics.stackexchange.com/questions/524471/can-elementary-particles-be-nicely-classified-into-force-transmitters-and-for) question).
No, it's not possible to stop an electron. because of the simple fact, it has to obey the Heisenberg uncertainty relation with respect to place and momentum.
In the extreme case (theoretically) we can measure the electron's momentum with absolute certainty. Which means we know absolutely nothing about the whereabouts of the electron (Heisenberg).
But how to find (or construct) such an electron? By an exact measurement? It would be a huge coincidence if the electron had indeed momentum zero. But this is all abstract and theoretical so, again, the answer is a big NO. | >
> So looking at wave nature of electron
>
>
>
The wave nature of the electron is not a wave nature in space for the individual electron, but in the probability of measuring it at (x,y,z,t). When you measure an electron you get a footprint of its extent in space compatible with a point particle. [This experiment](https://en.wikipedia.org/wiki/Double-slit_experiment#Interference_of_individual_particles) shows individual electrons, and the accumulation of electrons shows the wave nature. The particle table has the electron as [a point particle](https://en.wikipedia.org/wiki/Elementary_particle) .
Let us suppose that in the decay of some particles an electron is measured, and the four momenta of the input and output particles are measured. One can use Lorenz transformations and go the the kinetic frame where the electron has zero momentum. In contrast to photons, massive particles have a system where they can be at rest.
Whether in the laboratory one can cool electrons enough so that they can be considered at rest with the techniques shown [here](https://phys.org/news/2016-01-electrons-cool-quadrillionths.html) needs a specialist's answer.
Here is an experiment that describes the [cooling of electrons](https://blog.electronica.de/en/2014/09/23/cold-electrons/) down to -228C.
Even if one could have a gas of electrons at zero momentum, the repulsive forces between them would immediately set them moving.
Experiments that detect individual electrons rely on interactions of the electrons with some material. If they have zero momentum they would not be able to interact. That is why we have mathematical tools as the Lorenz transformations, and as they are validated for higher velocities, we accept their predictions for zero velocities. |
524,305 | We know that electrons have a dual nature just like EM waves (of course all the materials are said to have dual nature, noticeable or not). So looking at the wave nature of an electron and comparing this with photons, is it possible to make its kinetic energy equal to zero?
Copied form researchgate... | 2020/01/11 | [
"https://physics.stackexchange.com/questions/524305",
"https://physics.stackexchange.com",
"https://physics.stackexchange.com/users/249494/"
] | First of all, you can't compare photons with electrons. They are different types of particles (spin 1 vs spin1/2; force transmitter vs force emitter; see [this](https://physics.stackexchange.com/questions/524471/can-elementary-particles-be-nicely-classified-into-force-transmitters-and-for) question).
No, it's not possible to stop an electron. because of the simple fact, it has to obey the Heisenberg uncertainty relation with respect to place and momentum.
In the extreme case (theoretically) we can measure the electron's momentum with absolute certainty. Which means we know absolutely nothing about the whereabouts of the electron (Heisenberg).
But how to find (or construct) such an electron? By an exact measurement? It would be a huge coincidence if the electron had indeed momentum zero. But this is all abstract and theoretical so, again, the answer is a big NO. | Photons are pure kinetic energy.
>
> Moreover, you could say the energy of a photon is purely kinetic energy.
>
>
>
[Do photons have kinetic energy?](https://physics.stackexchange.com/questions/519526/do-photons-have-kinetic-energy)
But photons are massless. Electrons on the other hand, do have rest mass. It is very confusing when somebody learns about rest mass and thinks electrons can actually be brought to rest. In reality they cannot be. No one has ever experimentally seen an actual electron at rest.
Due to the HUP, when you try to restrict the electron to a very small region of space, the electron's position will be known with high certainty, thus, the electron's momentum (kinetic energy) will have extreme uncertainty (will rise). And vica versa. If you try to restrict the momentum of the electron (cooling), the electron's position will be known with extreme uncertainty.
>
> the uncertainty principle states that the more precisely the position of some particle is determined, the less precisely its momentum can be predicted from initial conditions, and vice versa.[2]
>
>
>
<https://en.wikipedia.org/wiki/Uncertainty_principle>
But I do understand where your question might come from. You can read phrases about electrons being standing (evanescent waves) as they exist around the nucleus.
>
> The electrons do not orbit the nucleus in the manner of a planet orbiting the sun, but instead exist as standing waves.
>
>
>
en.wikipedia.org/wiki/Atomic\_orbital
But this is very confusing because in reality electrons are quantum objects and cannot be brought to rest as per the HUP. This is QM. |
524,305 | We know that electrons have a dual nature just like EM waves (of course all the materials are said to have dual nature, noticeable or not). So looking at the wave nature of an electron and comparing this with photons, is it possible to make its kinetic energy equal to zero?
Copied form researchgate... | 2020/01/11 | [
"https://physics.stackexchange.com/questions/524305",
"https://physics.stackexchange.com",
"https://physics.stackexchange.com/users/249494/"
] | >
> So looking at wave nature of electron
>
>
>
The wave nature of the electron is not a wave nature in space for the individual electron, but in the probability of measuring it at (x,y,z,t). When you measure an electron you get a footprint of its extent in space compatible with a point particle. [This experiment](https://en.wikipedia.org/wiki/Double-slit_experiment#Interference_of_individual_particles) shows individual electrons, and the accumulation of electrons shows the wave nature. The particle table has the electron as [a point particle](https://en.wikipedia.org/wiki/Elementary_particle) .
Let us suppose that in the decay of some particles an electron is measured, and the four momenta of the input and output particles are measured. One can use Lorenz transformations and go the the kinetic frame where the electron has zero momentum. In contrast to photons, massive particles have a system where they can be at rest.
Whether in the laboratory one can cool electrons enough so that they can be considered at rest with the techniques shown [here](https://phys.org/news/2016-01-electrons-cool-quadrillionths.html) needs a specialist's answer.
Here is an experiment that describes the [cooling of electrons](https://blog.electronica.de/en/2014/09/23/cold-electrons/) down to -228C.
Even if one could have a gas of electrons at zero momentum, the repulsive forces between them would immediately set them moving.
Experiments that detect individual electrons rely on interactions of the electrons with some material. If they have zero momentum they would not be able to interact. That is why we have mathematical tools as the Lorenz transformations, and as they are validated for higher velocities, we accept their predictions for zero velocities. | Photons are pure kinetic energy.
>
> Moreover, you could say the energy of a photon is purely kinetic energy.
>
>
>
[Do photons have kinetic energy?](https://physics.stackexchange.com/questions/519526/do-photons-have-kinetic-energy)
But photons are massless. Electrons on the other hand, do have rest mass. It is very confusing when somebody learns about rest mass and thinks electrons can actually be brought to rest. In reality they cannot be. No one has ever experimentally seen an actual electron at rest.
Due to the HUP, when you try to restrict the electron to a very small region of space, the electron's position will be known with high certainty, thus, the electron's momentum (kinetic energy) will have extreme uncertainty (will rise). And vica versa. If you try to restrict the momentum of the electron (cooling), the electron's position will be known with extreme uncertainty.
>
> the uncertainty principle states that the more precisely the position of some particle is determined, the less precisely its momentum can be predicted from initial conditions, and vice versa.[2]
>
>
>
<https://en.wikipedia.org/wiki/Uncertainty_principle>
But I do understand where your question might come from. You can read phrases about electrons being standing (evanescent waves) as they exist around the nucleus.
>
> The electrons do not orbit the nucleus in the manner of a planet orbiting the sun, but instead exist as standing waves.
>
>
>
en.wikipedia.org/wiki/Atomic\_orbital
But this is very confusing because in reality electrons are quantum objects and cannot be brought to rest as per the HUP. This is QM. |
48,331 | **The [Atacama Large Millimeter Array](https://en.wikipedia.org/wiki/Atacama_Large_Millimeter_Array) or ALMA is a radio telescope complex** where signals from dozens of distributed dishes are routed to a single computer which performs interferometry and image processing computationally.
At about 5 kilometers altitude they are not in space yet, but traditional spinning magnetic hard drives [were not used due to the altitude](https://www.eso.org/public/news/eso1253/) and solid state drives were selected.
**The [Event Horizon Telescope](https://en.wikipedia.org/wiki/Event_Horizon_Telescope) is a cardboard box flown around the world** collecting stacks of hard drives, and okay, an array of radio telescopes, some at very high altitude. [This comment](https://astronomy.stackexchange.com/questions/28666/how-does-alma-produce-stable-mutually-coherent-thz-local-oscillators-for-all-o/39656?noredirect=1#comment80113_28666) links to the Western Digital post [What Does Helium Have to Do with the Black Hole Image?](https://blog.westerndigital.com/helium-filled-hdd-black-hole-image/) where I see that special helium filled and sealed hard drives were used so that they would work reliably at the high altitudes of some of the observatories in the network.
**Question:** Have traditional spinning hard drives ever been used in space outside of pressurized crewed areas? Ever beyond LEO? I'm excluding things like laptops and other computers used in the pressurized crewed areas of space stations, and would like to focus instead on any use of a **spinning disk of magnetic material addressed by a read-write head** in any other type of location.
We know that spacecraft including the Voyagers had magnetic tape recorders, and early weather satellites had magnetic video tape recorders, **but have spinning hard (or floppy for that matter!) disks of magnetic materials been used outside of pressurized crewed areas?**
---
Digital tape recorder (DTR):
* [How was magnetic tape decay prevented in Voyager 1?](https://space.stackexchange.com/q/2053/12102)
* [Did the designers of Voyager neglect the angular momentum of the tape recorders?](https://space.stackexchange.com/q/10223/12102)
* [Does the tape recorder on Voyager-1 still work?](https://space.stackexchange.com/q/15290/12102)
* [Voyager 1's tape recorder and other angular momentum management issues](https://space.stackexchange.com/q/17469/12102)
* [Voyager 1's tape recorder and other angular momentum management issues](https://space.stackexchange.com/q/17469/12102)
* Hackaday: [Interstellar 8-Track: The Not-So-Low-Tech Data Recorders of Voyager](https://hackaday.com/2018/11/29/interstellar-8-track-the-low-tech-data-recorders-of-voyager/)
Video recorder:
* [How did the TIROS video tape recorders record and playback images rather than audio; how were the signals modulated?](https://space.stackexchange.com/q/44985/12102)
* [How were video tape recorders adapted to work in orbit in 1962?](https://space.stackexchange.com/q/41418/12102)
For fun:
* [How (the heck) was coherent synthetic aperture radar (SAR) implemented using photographic emulsion aboard Apollo 17?](https://space.stackexchange.com/q/46941/12102) includes photo of a table full of hard drives presumably transported by the Event Horizon Telescope's worldwide network of cardboard boxes | 2020/11/03 | [
"https://space.stackexchange.com/questions/48331",
"https://space.stackexchange.com",
"https://space.stackexchange.com/users/12102/"
] | As far as I know, the only HDDs that have ever been used in space (excluding crewed areas) are a pair of Conner Peripherals [CP3540](http://bk0010.narod.ru/DRIVESPECS/CONNER/608.txt) 500 MB HDDs on the [MSTI-3](https://en.wikipedia.org/wiki/Miniature_Sensor_Technology_Integration-3) mission launched in May 1996. The mission lasted 18 months but did not go beyond low earth orbit. The two drives were mounted in a hermetically sealed enclosure. They were mounted back-to-back to avoid torque on the spacecraft during drive startup. There are a couple of very comprehensive reports from Scott Bussinger on the storage unit, [one from 1993](https://digitalcommons.usu.edu/cgi/viewcontent.cgi?article=2691&context=smallsat) before the mission and [one from 1998](https://apps.dtic.mil/sti/pdfs/ADA372706.pdf) after the mission.
This slide is from a presentation at the AVS conference a couple of years ago:[](https://i.stack.imgur.com/6BSLq.png) | Conventional hard drives cannot be used in the absence of air (or at high altitudes where the air is thin). They rely on a moving layer of air at the surface of the disk that allows the heads to 'fly' quite close to the surface. There are newer drives that are filled with helium and are hermetically sealed, so these can function at altitudes that conventional hard drives cannot tolerate. As an example, Seagate says:
>
> In general, most Seagate and Maxtor-brand drives are designed to work under the following specifications: Operating altitude (max): 3,048 meters (10,000 feet) Nonoperating altitude (max): 12,192 meters (40,000 feet)
>
>
>
A [Dell support knowledgebase entry](https://www.dell.com/support/article/en-us/sln80457/hard-drive-failures-caused-by-high-altitudes?lang=en) states something similar.
So, to answer your question in the general, no. Because they can not function at altitude or in (even higher altitude) space |
2,913,320 | I am about to start to developing backend site of a php project. Companies and site admins will login to this site and manage their data on the project.
My previous admin panel experiences were full of agony and pain. So I want to make sure that I choose correct tools for my purpose.
By the way, please note, I'm not looking for scaffolding. There won't be much tables in my database. Instead, there will be complex logic between entities.
I want clear seperation of markup and logic code and easy-to-use and standardized user-interface.
Thank you.
Edit:
-----
I understand this is very subjective. This is why I call it suggestion. I want to try a few of chunks of code before going along with one of them. | 2010/05/26 | [
"https://Stackoverflow.com/questions/2913320",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/253591/"
] | There is no perfect answer for this, it depends a lot of your (and your team) programming experience and your project's requirements.
As it talks about PHP and backoffice, I suggest you look at [symfony framework](http://www.symfony-project.org/). It's a RAD framework with great admin features and tons of plugins easing backpanel developement.
I understand you don't want scaffolding, in symfony you can choose to use a very customizable admin generator or build your own forms/listings (or mix between both, using generated as a good code base and extending it).
It comes with a great separation of concerns as it uses MVC paradigm, but aside from MVC it has form management sub-framework which can help a lot developing backoffice.
Be careful if you're not familiar with PHP5 OOP and MVC it could be little complex to learn and understand, but if your planning could allow you to have time to learn symfony programming, it's an experience I would recommand to every PHP developer.
This framework is very well documented, and as an introduction tutorial they offer a class around a website example with its backend application.
Of course, this is subjective and others would perhaps recommend you other choices. | Only recently went through a couple of frameworks about a month ago for a site I was working on and found CodeIgniter was easiest to get up and running and had the best documentation and tutorials.
<http://codeigniter.com/>
Alternatives are symphony, cakePHP and Kohona |
2,751,227 | I see something strange like:
<http://github.com/zoul/Finch.git>
Now I'm not that CVS, SVN, etc. dude. When I open that in the browser it tells me that I did something wrong. So I bet I need some hacker-style tool? Some client?
(I mean... why not just provide a ZIP file? Isn't the world complex enough?) | 2010/05/01 | [
"https://Stackoverflow.com/questions/2751227",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/268733/"
] | I've been stumped by this too. The "Download" button is to the far right, but you also need to be in the top folder in order to download what you're seeing. Go up as high as you can to the parent/root folder and then look for the download button. | Sometimes if the 'Download ZIP' button is not available, you can click on 'Raw' and the file should download to your system. |
2,751,227 | I see something strange like:
<http://github.com/zoul/Finch.git>
Now I'm not that CVS, SVN, etc. dude. When I open that in the browser it tells me that I did something wrong. So I bet I need some hacker-style tool? Some client?
(I mean... why not just provide a ZIP file? Isn't the world complex enough?) | 2010/05/01 | [
"https://Stackoverflow.com/questions/2751227",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/268733/"
] | I've been stumped by this too. The "Download" button is to the far right, but you also need to be in the top folder in order to download what you're seeing. Go up as high as you can to the parent/root folder and then look for the download button. | I was facing same problem but accidentlty I sorted this problem.
1) Login in github
2) Click on Fork Button at Top Right.
3) After above step you can see Clone or download in Green color under <> Code Tab. |
13,567 | Is there anything you can add to a guacamole recipe to prevent it from going brown so quickly? Or a specific way to package it for very short-term storage (usually only about two days). I tend to make large batches when I do make it, and by the next day its already looking pretty sad. I usually just mix it up again and it doesn't look as bad, but I figured someone may know a trick to prevent it all together
Thanks! | 2011/03/29 | [
"https://cooking.stackexchange.com/questions/13567",
"https://cooking.stackexchange.com",
"https://cooking.stackexchange.com/users/5193/"
] | Guacamole seems to go brown with exposure to air, as does avocado. While it will not solve the issue entirely, covering with cling wrap directly on the surface helps maintain color for an extended period. Rather than pulling the wrap tight across the top of a bowl / container, place the wrap directly on top of the guacamole. Use your hand to smooth out the top so that no air is between the cling wrap and guacamole. This requires a bit extra cling wrap, as you need to get it up the insides of your bowl, but it makes a significant difference. | I have not tried it myself, but it is always said that keeping the core of the avocado and sticking it in the middle of the guacamole prevents it from turning brown. |
13,567 | Is there anything you can add to a guacamole recipe to prevent it from going brown so quickly? Or a specific way to package it for very short-term storage (usually only about two days). I tend to make large batches when I do make it, and by the next day its already looking pretty sad. I usually just mix it up again and it doesn't look as bad, but I figured someone may know a trick to prevent it all together
Thanks! | 2011/03/29 | [
"https://cooking.stackexchange.com/questions/13567",
"https://cooking.stackexchange.com",
"https://cooking.stackexchange.com/users/5193/"
] | Guacamole seems to go brown with exposure to air, as does avocado. While it will not solve the issue entirely, covering with cling wrap directly on the surface helps maintain color for an extended period. Rather than pulling the wrap tight across the top of a bowl / container, place the wrap directly on top of the guacamole. Use your hand to smooth out the top so that no air is between the cling wrap and guacamole. This requires a bit extra cling wrap, as you need to get it up the insides of your bowl, but it makes a significant difference. | Guac - one of my favorites. First, as others have stated, make sure that you use some citrus in the recipe. Then use the cling wrap - don't pull it tight over the bowl, which traps air in the container. Lightly press the cling wrap down on the surface of the quac, eliminating air from the surface. |
13,567 | Is there anything you can add to a guacamole recipe to prevent it from going brown so quickly? Or a specific way to package it for very short-term storage (usually only about two days). I tend to make large batches when I do make it, and by the next day its already looking pretty sad. I usually just mix it up again and it doesn't look as bad, but I figured someone may know a trick to prevent it all together
Thanks! | 2011/03/29 | [
"https://cooking.stackexchange.com/questions/13567",
"https://cooking.stackexchange.com",
"https://cooking.stackexchange.com/users/5193/"
] | Guacamole seems to go brown with exposure to air, as does avocado. While it will not solve the issue entirely, covering with cling wrap directly on the surface helps maintain color for an extended period. Rather than pulling the wrap tight across the top of a bowl / container, place the wrap directly on top of the guacamole. Use your hand to smooth out the top so that no air is between the cling wrap and guacamole. This requires a bit extra cling wrap, as you need to get it up the insides of your bowl, but it makes a significant difference. | Bill Tate, I did not expect to find you here. I've found that lime juice works just fine to keep it from going too brown, in combination with the "saran wrap directly on the guac" trick. Then again, are you going to trust a guy who eat raw eggs? |
13,567 | Is there anything you can add to a guacamole recipe to prevent it from going brown so quickly? Or a specific way to package it for very short-term storage (usually only about two days). I tend to make large batches when I do make it, and by the next day its already looking pretty sad. I usually just mix it up again and it doesn't look as bad, but I figured someone may know a trick to prevent it all together
Thanks! | 2011/03/29 | [
"https://cooking.stackexchange.com/questions/13567",
"https://cooking.stackexchange.com",
"https://cooking.stackexchange.com/users/5193/"
] | Guac - one of my favorites. First, as others have stated, make sure that you use some citrus in the recipe. Then use the cling wrap - don't pull it tight over the bowl, which traps air in the container. Lightly press the cling wrap down on the surface of the quac, eliminating air from the surface. | Bill Tate, I did not expect to find you here. I've found that lime juice works just fine to keep it from going too brown, in combination with the "saran wrap directly on the guac" trick. Then again, are you going to trust a guy who eat raw eggs? |
13,567 | Is there anything you can add to a guacamole recipe to prevent it from going brown so quickly? Or a specific way to package it for very short-term storage (usually only about two days). I tend to make large batches when I do make it, and by the next day its already looking pretty sad. I usually just mix it up again and it doesn't look as bad, but I figured someone may know a trick to prevent it all together
Thanks! | 2011/03/29 | [
"https://cooking.stackexchange.com/questions/13567",
"https://cooking.stackexchange.com",
"https://cooking.stackexchange.com/users/5193/"
] | Guacamole seems to go brown with exposure to air, as does avocado. While it will not solve the issue entirely, covering with cling wrap directly on the surface helps maintain color for an extended period. Rather than pulling the wrap tight across the top of a bowl / container, place the wrap directly on top of the guacamole. Use your hand to smooth out the top so that no air is between the cling wrap and guacamole. This requires a bit extra cling wrap, as you need to get it up the insides of your bowl, but it makes a significant difference. | interesting info thanks. I eat avocadoes regularly as a diet food. I use lots of lemon juice (1 whole lemon per avocado) and add coarsely ground sea salt and black pepper and eat it by the spoonful, yummo! Often I will only eat 1/2 of the fruit at a time. So I squeeze lemon juice all over the exposed part of the fruit with some in the well where the seed was. Then I place it in a clip lock platic bag and place in the fridge for a day or two. It works like a charm. However, the skin is still attached but not the seed. Maybe something in that ? |
13,567 | Is there anything you can add to a guacamole recipe to prevent it from going brown so quickly? Or a specific way to package it for very short-term storage (usually only about two days). I tend to make large batches when I do make it, and by the next day its already looking pretty sad. I usually just mix it up again and it doesn't look as bad, but I figured someone may know a trick to prevent it all together
Thanks! | 2011/03/29 | [
"https://cooking.stackexchange.com/questions/13567",
"https://cooking.stackexchange.com",
"https://cooking.stackexchange.com/users/5193/"
] | I have not tried it myself, but it is always said that keeping the core of the avocado and sticking it in the middle of the guacamole prevents it from turning brown. | Bill Tate, I did not expect to find you here. I've found that lime juice works just fine to keep it from going too brown, in combination with the "saran wrap directly on the guac" trick. Then again, are you going to trust a guy who eat raw eggs? |
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