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Semiconductor devices are electronic components that exploit the electronic properties of semiconductor materials, principally silicon, germanium, and gallium arsenide, as well as organic semiconductors. Semiconductor devices have replaced thermionic devices (vacuum tubes) in most applications. They use electronic conduction in the solid state as opposed to the gaseous state or thermionic emission in a high vacuum.
Semiconductor devices are manufactured both as single discrete devices and as integrated circuits (ICs), which consist of a number—from a few (as low as two) to billions—of devices manufactured and interconnected on a single semiconductor substrate, or wafer.
Semiconductor materials are useful because their behavior can be easily manipulated by the addition of impurities, known as doping. Semiconductor conductivity can be controlled by the introduction of an electric or magnetic field, by exposure to light or heat, or by the mechanical deformation of a doped monocrystalline grid; thus, semiconductors can make excellent sensors. Current conduction in a semiconductor occurs via mobile or "free" electrons and holes, collectively known as charge carriers. Doping a semiconductor such as silicon with a small proportion of an atomic impurity, such as phosphorus or boron, greatly increases the number of free electrons or holes within the semiconductor. When a doped semiconductor contains excess holes it is called "p-type", and when it contains excess free electrons it is known as "n-type", where p (positive for holes) or n (negative for electrons) is the sign of the charge of the majority mobile charge carriers. The semiconductor material used in devices is doped under highly controlled conditions in a fabrication facility, or fab, to control precisely the location and concentration of p- and n-type dopants. The junctions which form where n-type and p-type semiconductors join together are called p–n junctions.
Semiconductor devices made per year have been growing by 9.1% on average since 1978 and shipments in 2018 are predicted for the first time to exceed 1 trillion, meaning well over 7 trillion has been made to date, in just in the decade prior.
A semiconductor diode is a device typically made from a single p–n junction. At the junction of a p-type and an n-type semiconductor there forms a depletion region where current conduction is inhibited by the lack of mobile charge carriers. When the device is forward biased (connected with the p-side at higher electric potential than the n-side), this depletion region is diminished, allowing for significant conduction, while only very small current can be achieved when the diode is reverse biased and thus the depletion region expanded.
Exposing a semiconductor to light can generate electron–hole pairs, which increases the number of free carriers and thereby the conductivity. Diodes optimized to take advantage of this phenomenon are known as photodiodes. Compound semiconductor diodes can also be used to generate light, as in light-emitting diodes and laser diodes.
Bipolar junction transistors are formed from two p–n junctions, in either n–p–n or p–n–p configuration. The middle, or base, region between the junctions is typically very narrow. The other regions, and their associated terminals, are known as the emitter and the collector. A small current injected through the junction between the base and the emitter changes the properties of the base-collector junction so that it can conduct current even though it is reverse biased. This creates a much larger current between the collector and emitter, controlled by the base-emitter current.
Another type of transistor, the field-effect transistor, operates on the principle that semiconductor conductivity can be increased or decreased by the presence of an electric field. An electric field can increase the number of free electrons and holes in a semiconductor, thereby changing its conductivity. The field may be applied by a reverse-biased p–n junction, forming a junction field-effect transistor (JFET) or by an electrode insulated from the bulk material by an oxide layer, forming a metal–oxide–semiconductor field-effect transistor (MOSFET).
The MOSFET, a solid-state device, is the most used semiconductor device today. The gate electrode is charged to produce an electric field that controls the conductivity of a "channel" between two terminals, called the source and drain. Depending on the type of carrier in the channel, the device may be an n-channel (for electrons) or a p-channel (for holes) MOSFET. Although the MOSFET is named in part for its "metal" gate, in modern devices polysilicon is typically used instead.
By far, silicon (Si) is the most widely used material in semiconductor devices. Its combination of low raw material cost, relatively simple processing, and a useful temperature range makes it currently the best compromise among the various competing materials. Silicon used in semiconductor device manufacturing is currently fabricated into boules that are large enough in diameter to allow the production of 300 mm (12 in.) wafers.
Germanium (Ge) was a widely used early semiconductor material but its thermal sensitivity makes it less useful than silicon. Today, germanium is often alloyed with silicon for use in very-high-speed SiGe devices; IBM is a major producer of such devices.
Gallium arsenide (GaAs) is also widely used in high-speed devices but so far, it has been difficult to form large-diameter boules of this material, limiting the wafer diameter to sizes significantly smaller than silicon wafers thus making mass production of GaAs devices significantly more expensive than silicon.
Other less common materials are also in use or under investigation.
Silicon carbide (SiC) has found some application as the raw material for blue light-emitting diodes (LEDs) and is being investigated for use in semiconductor devices that could withstand very high operating temperatures and environments with the presence of significant levels of ionizing radiation. IMPATT diodes have also been fabricated from SiC.
Various indium compounds (indium arsenide, indium antimonide, and indium phosphide) are also being used in LEDs and solid state laser diodes. Selenium sulfide is being studied in the manufacture of photovoltaic solar cells.
All transistor types can be used as the building blocks of logic gates, which are fundamental in the design of digital circuits. In digital circuits like microprocessors, transistors act as on-off switches; in the MOSFET, for instance, the voltage applied to the gate determines whether the switch is on or off.
Transistors used for analog circuits do not act as on-off switches; rather, they respond to a continuous range of inputs with a continuous range of outputs. Common analog circuits include amplifiers and oscillators.
Circuits that interface or translate between digital circuits and analog circuits are known as mixed-signal circuits.
Power semiconductor devices are discrete devices or integrated circuits intended for high current or high voltage applications. Power integrated circuits combine IC technology with power semiconductor technology, these are sometimes referred to as "smart" power devices. Several companies specialize in manufacturing power semiconductors.
The type designators of semiconductor devices are often manufacturer specific. Nevertheless, there have been attempts at creating standards for type codes, and a subset of devices follow those. For discrete devices, for example, there are three standards: JEDEC JESD370B in United States, Pro Electron in Europe and Japanese Industrial Standards (JIS) in Japan.
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Semiconductors had been used in the electronics field for some time before the invention of the transistor. Around the turn of the 20th century they were quite common as detectors in radios, used in a device called a "cat's whisker" developed by Jagadish Chandra Bose and others. These detectors were somewhat troublesome, however, requiring the operator to move a small tungsten filament (the whisker) around the surface of a galena (lead sulfide) or carborundum (silicon carbide) crystal until it suddenly started working. Then, over a period of a few hours or days, the cat's whisker would slowly stop working and the process would have to be repeated. At the time their operation was completely mysterious. After the introduction of the more reliable and amplified vacuum tube based radios, the cat's whisker systems quickly disappeared. The "cat's whisker" is a primitive example of a special type of diode still popular today, called a Schottky diode.
During World War II, radar research quickly pushed radar receivers to operate at ever higher frequencies and the traditional tube based radio receivers no longer worked well. The introduction of the cavity magnetron from Britain to the United States in 1940 during the Tizard Mission resulted in a pressing need for a practical high-frequency amplifier.
On a whim, Russell Ohl of Bell Laboratories decided to try a cat's whisker. By this point they had not been in use for a number of years, and no one at the labs had one. After hunting one down at a used radio store in Manhattan, he found that it worked much better than tube-based systems.
Ohl investigated why the cat's whisker functioned so well. He spent most of 1939 trying to grow more pure versions of the crystals. He soon found that with higher quality crystals their finicky behaviour went away, but so did their ability to operate as a radio detector. One day he found one of his purest crystals nevertheless worked well, and it had a clearly visible crack near the middle. However as he moved about the room trying to test it, the detector would mysteriously work, and then stop again. After some study he found that the behaviour was controlled by the light in the room–more light caused more conductance in the crystal. He invited several other people to see this crystal, and Walter Brattain immediately realized there was some sort of junction at the crack.
Further research cleared up the remaining mystery. The crystal had cracked because either side contained very slightly different amounts of the impurities Ohl could not remove–about 0.2%. One side of the crystal had impurities that added extra electrons (the carriers of electric current) and made it a "conductor". The other had impurities that wanted to bind to these electrons, making it (what he called) an "insulator". Because the two parts of the crystal were in contact with each other, the electrons could be pushed out of the conductive side which had extra electrons (soon to be known as the emitter) and replaced by new ones being provided (from a battery, for instance) where they would flow into the insulating portion and be collected by the whisker filament (named the collector). However, when the voltage was reversed the electrons being pushed into the collector would quickly fill up the "holes" (the electron-needy impurities), and conduction would stop almost instantly. This junction of the two crystals (or parts of one crystal) created a solid-state diode, and the concept soon became known as semiconduction. The mechanism of action when the diode is off has to do with the separation of charge carriers around the junction. This is called a "depletion region".
Armed with the knowledge of how these new diodes worked, a vigorous effort began to learn how to build them on demand. Teams at Purdue University, Bell Labs, MIT, and the University of Chicago all joined forces to build better crystals. Within a year germanium production had been perfected to the point where military-grade diodes were being used in most radar sets.
After the war, William Shockley decided to attempt the building of a triode-like semiconductor device. He secured funding and lab space, and went to work on the problem with Brattain and John Bardeen.
The key to the development of the transistor was the further understanding of the process of the electron mobility in a semiconductor. It was realized that if there were some way to control the flow of the electrons from the emitter to the collector of this newly discovered diode, an amplifier could be built. For instance, if contacts are placed on both sides of a single type of crystal, current will not flow between them through the crystal. However if a third contact could then "inject" electrons or holes into the material, current would flow.
Actually doing this appeared to be very difficult. If the crystal were of any reasonable size, the number of electrons (or holes) required to be injected would have to be very large, making it less than useful as an amplifier because it would require a large injection current to start with. That said, the whole idea of the crystal diode was that the crystal itself could provide the electrons over a very small distance, the depletion region. The key appeared to be to place the input and output contacts very close together on the surface of the crystal on either side of this region.
Brattain started working on building such a device, and tantalizing hints of amplification continued to appear as the team worked on the problem. Sometimes the system would work but then stop working unexpectedly. In one instance a non-working system started working when placed in water. Ohl and Brattain eventually developed a new branch of quantum mechanics, which became known as surface physics, to account for the behaviour. The electrons in any one piece of the crystal would migrate about due to nearby charges. Electrons in the emitters, or the "holes" in the collectors, would cluster at the surface of the crystal where they could find their opposite charge "floating around" in the air (or water). Yet they could be pushed away from the surface with the application of a small amount of charge from any other location on the crystal. Instead of needing a large supply of injected electrons, a very small number in the right place on the crystal would accomplish the same thing.
Their understanding solved the problem of needing a very small control area to some degree. Instead of needing two separate semiconductors connected by a common, but tiny, region, a single larger surface would serve. The electron-emitting and collecting leads would both be placed very close together on the top, with the control lead placed on the base of the crystal. When current flowed through this "base" lead, the electrons or holes would be pushed out, across the block of semiconductor, and collect on the far surface. As long as the emitter and collector were very close together, this should allow enough electrons or holes between them to allow conduction to start.
The Bell team made many attempts to build such a system with various tools, but generally failed. Setups where the contacts were close enough were invariably as fragile as the original cat's whisker detectors had been, and would work briefly, if at all. Eventually they had a practical breakthrough. A piece of gold foil was glued to the edge of a plastic wedge, and then the foil was sliced with a razor at the tip of the triangle. The result was two very closely spaced contacts of gold. When the wedge was pushed down onto the surface of a crystal and voltage applied to the other side (on the base of the crystal), current started to flow from one contact to the other as the base voltage pushed the electrons away from the base towards the other side near the contacts. The point-contact transistor had been invented.
While the device was constructed a week earlier, Brattain's notes describe the first demonstration to higher-ups at Bell Labs on the afternoon of 23 December 1947, often given as the birthdate of the transistor. What is now known as the "p–n–p point-contact germanium transistor" operated as a speech amplifier with a power gain of 18 in that trial. John Bardeen, Walter Houser Brattain, and William Bradford Shockley were awarded the 1956 Nobel Prize in physics for their work.
Bell Telephone Laboratories needed a generic name for their new invention: "Semiconductor Triode", "Solid Triode", "Surface States Triode" [sic], "Crystal Triode" and "Iotatron" were all considered, but "transistor", coined by John R. Pierce, won an internal ballot. The rationale for the name is described in the following extract from the company's Technical Memoranda (May 28, 1948)  calling for votes:
Transistor. This is an abbreviated combination of the words "transconductance" or "transfer", and "varistor". The device logically belongs in the varistor family, and has the transconductance or transfer impedance of a device having gain, so that this combination is descriptive.
Shockley was upset about the device being credited to Brattain and Bardeen, who he felt had built it "behind his back" to take the glory. Matters became worse when Bell Labs lawyers found that some of Shockley's own writings on the transistor were close enough to those of an earlier 1925 patent by Julius Edgar Lilienfeld that they thought it best that his name be left off the patent application.
Shockley was incensed, and decided to demonstrate who was the real brains of the operation. A few months later he invented an entirely new, considerably more robust, type of transistor with a layer or 'sandwich' structure. This structure went on to be used for the vast majority of all transistors into the 1960s, and evolved into the bipolar junction transistor.
With the fragility problems solved, a remaining problem was purity. Making germanium of the required purity was proving to be a serious problem, and limited the yield of transistors that actually worked from a given batch of material. Germanium's sensitivity to temperature also limited its usefulness. Scientists theorized that silicon would be easier to fabricate, but few investigated this possibility. Gordon K. Teal was the first to develop a working silicon transistor, and his company, the nascent Texas Instruments, profited from its technological edge. From the late 1960s most transistors were silicon-based. Within a few years transistor-based products, most notably easily portable radios, were appearing on the market.
The static induction transistor, the first high frequency transistor, was invented by Japanese engineers Jun-ichi Nishizawa and Y. Watanabe in 1950. It was the fastest transistor through to the 1980s.
A major improvement in manufacturing yield came when a chemist advised the companies fabricating semiconductors to use distilled rather than tap water: calcium ions present in tap water were the cause of the poor yields. "Zone melting", a technique using a band of molten material moving through the crystal, further increased crystal purity.
Annual semiconductor unit shipments (integrated circuits and opto-sensor-discretes, or O-S-D, devices) are expected to grow 9% [..] For 2018, semiconductor unit shipments are forecast to climb to 1,075.1 billion, which equates to 9% growth for the year. Starting in 1978 with 32.6 billion units and going through 2018, the compound annual growth rate for semiconductor units is forecast to be 9.1%, a solid growth figure over the 40 year span. [..] In 2018, O-S-D devices are forecast to account for 70% of total semiconductor units compared to 30% for ICs.


The following is one of a series of guest posts by Mike Shelby. Mike is a former ESL teacher who has been quietly (i.e., without his own blog) disseminating his thoughts on language learning around the internet for quite some time.
Have you noticed that interpreters have to possess the most thorough knowledge of a foreign language, especially of conversation, vocabulary and grammar? Perhaps foreign learners of English can achieve fluency in English also through oral translation from their native language into English. It is possible to check oneself this way when practicing speaking in English every sentence in ready-made materials with both native-language and English versions. I also believe that the value of oral translation from a native language into English with self-check is underestimated by English teaching specialists for self-study and self-practice of English conversation, vocabulary and grammar. Oral translation practice should cover English grammar, conversation, and vocabulary. Thematic dialogues, questions and answers on conversation topics, thematic texts (informative texts and narrative stories), grammatical usage sentences, and sentences with difficult vocabulary on various topics, especially with fixed phrases and idioms, can be used in practicing English through oral translation from one's native language into English.
My views on oral translation do not apply to classroom teaching and classroom learning of English when an ESL teacher teaches English to students from various ethnic backgrounds. In that setting, oral translation from a native language into English is simply impossible. All explanations of English pronunciation, grammar, and vocabulary to learners from different ethnic backgrounds have to be done in English only at English classes. As you know there are English courses in English only for learning and practicing all four skills in one course in each lesson (listening, speaking, reading, and writing alongside pronunciation, grammar, and vocabulary). Four-skill English courses include textbooks with audio and video recordings for all levels, including for beginners, and are suitable for self-study as well. There are also online English-learning courses in English only.
I firmly believe that oral translation from a native language into English is effective in practicing English speaking, vocabulary, and grammar on one's own with ready-made materials using self-check in a more logical, thorough, in-depth way as to content than casual talking to native-English speakers. practicing English on one's own through oral translation into English with self-check may be a quicker way for developing fluency in speaking English than casual talking to native-English speakers with limited content.
Of course, everyday long-term talking to native English speakers on a multitude of topics is a top priority and a paramount factor for developing good English-speaking skills by learners of English. Exercises in listening, speaking, and reading in English that also cover English pronunciation, grammar, vocabulary, and conversation on various topics belong to major English-learning and -teaching activities. I do not advocate oral translation into English as the only or the most important method in learning English grammar, vocabulary, and speaking.
However, self-study and practicing English on one's own are indispensable and substantially accelerate success in English. Communication with native-English speakers can't encompass all aspects of mastering English adequately and thoroughly, especially vocabulary, grammar, and the potential in-depth content of conversations suitable for the real-life needs of students for using English. It's possible and effective to practice English (including listening comprehension and speaking) on one's own through self-check using transcripts, books, and audio and video aids.
Oral translation into English allows speaking a wide variety of sentences on a multitude of topics with sophisticated important content (sentences) that are rarely widely used in daily life because of limited opportunity and limited content of communication of foreign learners with native speakers of English. Oral translation from a native language into English is very important and effective for foreign learners of English because oral translation into English creates solid additional extensive practice of English that is rarely possible in terms of comprehensive content in daily communication with native speakers of English.


The NExT Digital Handbook currently contains 61 reproducible PDFs. Each PDF title is listed here according to table numbers within each corresponding chapter.
How to Engage the PDFs within the NExT Digital Handbook
Click on the orange ‘table # button’ to open PDFs within each chapter.
A reproducible (PDF) icon button is located at the bottom of each PDF. Click to download or print.
Click the ‘X’ located at the top right corner of each PDF to return back to the digital handbook content.
Table 1.1 - Central Tasks of Learning to Teach
Table 2.1 - Examples of Multiple Measures of Teacher Effectiveness
Table 3.1 - NExT Common Metrics Surveys
Table 3.2 - Tips for Locating First Year Teachers for Survey Administration
Table 3.3 - Template for Reporting Aligned Survey Items for Teaching Practice
Table 3.4 - Example of Reporting Aligned Survey Items for Teaching Practice
Table 3.5 - Making Sense of Multiple Measures
Table 4.1 - Possible Sampling Strategies
Table 4.2 - Teacher Recruitment Template
Table 4.3 - Template for Principal Contacts
Table 4.4 - Preparing for a Student Work Sample Interview
Table 4.5 - Student Work Sample Interview Protocol
Table 4.6 - Student Impact Rubric
Table 4.7 - Template for Recognizing the Teacher Participant
Table 4.8 - Focus Group on Student Impact Protocol
Table 4.9 - Components of Quality Case Studies
Table 4.10 - Survey of Student Engagement K-6
Table 4.11 - Survey of Student Engagement 7-12
Table 4.12 - Levels of Engagement - Adapted from Schlecty (2002)
Table 4.13 - Impact on Student Learning Project
Table 4.14 - Gathering Pre-Post Data on a Specific Strategy
Table 4.15 - Comparative Group Studies of Student Learning
Table 5.1 - Central Tasks of Learning to Teach
Table 5.2 - School Assessments: Data-Focused PLCs Embedded in the School Context
Table 5.3 - Teacher Preparation Program Assessment: Data-Focused PLCs Embedded in the Preparation Program
Table 5.4 - Resources for Principals or Instructional Coaches about Data-Focused PLCs
Table 5.5 - Resources for Teacher Educators about Data-Focused PLCs
Table 5.6 - School Assessment: Communication Systems Supporting a Collaborative School Climate


What if you’ve been asked to provide “accessible eLearning?” Either you need to build new courses that are accessible, or to re-develop existing courses to make them accessible.
First step—figure out what “accessible” means. What? You mean there isn’t a cut-and-dried standard out there that says exactly what needs to be done?
Here’s the part where I’d love to give you a simple, one-sentence answer. Actually, I can do that: “Accessible eLearning is eLearning that can be experienced by everyone, even those with disabilities.”
Unfortunately, the simple answer doesn’t begin to capture the complexity and variation in how the term “accessibility” is applied to eLearning, so I’m going to attempt a more thorough definition here.
Accessible eLearning involves understanding a few key factors: standards, learners, and design.
Standards and guidelines: Compliance with standards and guidelines is a key component of accessibility, and often the one that gets the most attention. There are many guidelines to encourage compliance with various accessibility laws and regulations, but the 2 that are most often applied to eLearning are Section 508 and Web Content and Accessibility Guidelines (WCAG) 2.0.
Looking at these detailed and extensive guidelines, you might think, “Oh, this is accessibility,” but accessibility is more complicated than just meeting these standards. Mainly because what qualifies as “meeting” these guidelines is often open to interpretation and in many areas it’s not even close to as cut-and-dried as many believe it is.
The goal of accessibility is to provide an equivalent learning experience for all learners. This involves more than checking off compliance with each technical standard. Designing for non-disabled learners and then applying accessible standards and guidelines like tags and transcripts might provide an equivalent experience some of the time, but it’s not really a reliable approach. We’ve learned that the best way to ensure a truly equivalent learning experience is to consider all learners and design for them.
Learners: The best learning experiences are learner-centered, and accessible eLearning is no exception. Accessible eLearning means defining your audience to include those with disabilities, and then designing to meet the needs of the entire audience. You may be familiar with meeting the needs of learners with visual or hearing impairments, but the scope of learners included in the “accessible eLearning” definition is broader than that.
For example, some learners are not able to use a mouse, or have limited keyboard use. These differing abilities have to be accommodated in the design and construction of the course. At Fredrickson, we start by developing personas to represent each learner group—to represent both roles who are an audience for the content and different ways of accessing the courses.
Design: Designing for accessibility is designing for good learning. It should be thought of as more than meeting a set of guidelines—rather an approach of creating an experience for all learners. In the same way we would design to meet learning objectives, we design to meet accessibility expectations…and to do this accessibility has to be integrated into our design process.
A key credo of accessible design at Fredrickson is, “Design accessibility from the beginning!” Understanding learners and thinking through their experience throughout design and development is key.
Which brings me to the point about “adding” accessibility to existing eLearning courses. Simply put, making eLearning accessible when it’s already built is essentially re-engineering. Believe me, I wish there were a magic “Easy Button” that provided a fast, cheap, and 100% foolproof way to make courses accessible by just uploading them into a tool that would then spit out an accessible version of the course, but that’s just not reality. We’ve developed best practices at Fredrickson for re-designing to create equivalent learner experiences when existing courses need to be made accessible, so we can streamline this part of the process. But then we still need to build it, so while experience and methodology can help make the process more efficient, there is no shortcut to accessible learning.
Understanding these factors of accessibility will help you start to think about how to approach accessible learning at your organization.


Few details about these machines are known. I have covered the K-37 here. An article in agentura.ru says that the B-4 was built in the 1930’s and used in Spain during the civil war, in the Far East border incidents with Japan and in the Russo-Finnish war of 1940.
A modernized version of the B-4 called M-100 was built in 1940 and installed in American busses in order to provide mobility (it weighed 141kg). By the summer of 1941 there were 96 sets of the M-100 in service.
In 1943 a more compact version of the M-100 was built and given the designation M-101.
The agentura piece does not give details on the characteristics of these machines.
German interception of Soviet radio-teletype networks
During the 1930’s the SU started to use radio-teletype. Since 1936 the Germans had equipment that automatically intercepted and printed this traffic.
From TICOM reports it seems that the military networks used 2-channel teleprinters while the economic links used multichannel systems.
The 2-channel links employing cipher T/P assigned one channel for the cipher traffic and the other for operator ‘chat’.
There were at least three agencies that intercepted this traffic.
1). The Army Ordnance, Development and Testing Group, Signal Branch Group IV C - Wa Pruef 7/IV C at an experimental station in Hillersleben-Staats.
2). The Forschungsamt, an agency reporting directly to Hermann Goering.
3). The Army’s signal intelligence agency OKH/GdNA/In 7/VI (General der Nachrichtenaufklaerung) and its Group VI - OKH/GdNA Group VI.
Forschungsamt success in 1943
In 1943 the Forschungsamt informed the Army agency of their success in reconstructing a Soviet cipher teleprinter used between Moscow and the Fronts. This machine was solved because during every pause seven characters of pure ‘key’ were transmitted. A meeting was held in September 1943 between Councilor Paetzel (head of the FA’s cipher research department), Councilor Kroeger (the FA’s cipher machine specialist) and the Army agency’s Dr Pietsch (head of the mathematical research department) and Doering (head of cipher machine research).
The Soviet machine had 6 wheels. Five enciphered the respective Baudot impulses while the sixth controlled their movement.
The wheels had the following positions (pins):
wheel I – 49
wheel II – 47
wheel III – 46
wheel IV – 45
wheel V – 41
wheel VI – 43
The Soviet scrambler corresponded to the left portion of the German SZ 40/42 cipher attachment. The Forschungsamt people stated that they would build a copy of this machine in order to decrypt this traffic more efficiently.
More details about the Forschungsamt solution of the Soviet cipher teleprinter are given by Bruno Kröger in TICOM reports DF-240 and DF-241. Kröger was the FA’s cipher machine expert and during the war he solved not only the Soviet machine but also the Swiss diplomatic Enigma K.
The Soviet cipher teleprinter was used on 2-channel networks and the FA’s Technical Division was able to build equipment that automatically intercepted and printed this radio traffic. The cipher text was then examined by Kröger’s department and it was discovered that during transmission pauses the Russian letter П was enciphered seven times in succession. Messages interrupted by transmission pauses were examined and their first and last seven characters analyzed in order to uncover the operating principles of the device.
Through this cryptanalytic procedure it was possible to find out that the machine had 6 wheels that stepped regularly, then their pin arrangement was identified and with the daily key recovered all the day’s traffic could be solved.
This success however turned out to be short lived since in late 1943 the Soviet cipher machine was modified and no pure ‘key’ was transmitted during transmission pauses. It seems that from then on this traffic was only examined by the Army’s Inspectorate 7/VI.
Efforts of the Army signal intelligence agency
The Army agency Inspectorate 7/VI assigned its own unit to intercept and evaluate this traffic. This was Group VI operating during 1942-44 from Loetzen, East Prussia.
Unteroffizier Karrenberg, the member of that unit assigned to work on the cipher teleprinter said in postwar interrogations that this traffic was first intercepted in 1940 in Warsaw. However it was not systematically collected and analyzed till summer 1943. They called this traffic ‘Bandwurm’ because of the non-repeating cipher.
There were 8 T/P links from the Army Fronts to Moscow plus 2-3 Airforce links and a link to the Far East command. It was also used by the NKVD. There was no direct T/P link between the individual Front staffs. Instead messages had to be routed through Moscow.
According to Karrenberg the machine had two settings a large and a small. The large setting gave a simple substitution because the wheels did not turn. This was used for operator ‘chat’. The small setting gave an endless column substitution since the wheels moved.
In TICOM report I-153 he says: ‘In Autumn 1944 both the end of 'adder' and every pause in the cipher proper was preceded by seven key letters [redacted]. Then the traffic went off the air and reappeared in December with no external change except that the seven ‘residue' letters had been reduced to three, suggesting a modification of the machine’. In TICOM report I-30 he says that the attachment had 5 small wheels driven by a large one with a period of 43.
These were the same characteristic observed in the machine analyzed by the Forschungsamt. However another OKH cryptanalyst named Buggisch says that the FA machine and the ‘Bandwurm’ were different.
Buggisch was assistant to Doering in the cipher machine research section of Inspectorate 7/VI. In his interrogation TICOM I-64 he says that the cycle of one wheel was 37 and the others 30-80. The machine was analyzed by the mathematics department and a cryptanalyst Troeblicher or Troebliger played a leading part. Thanks to a ‘compromise’ of 8 messages enciphered with the same settings 1.400 characters of pure ‘key’ were recovered. However they were not able to solve the machine because they lacked the manpower.
Unfortunately Buggisch left the OKH agency in June 1944 so he did not know anything more.
The Germans may have failed to solve this machine but they were able to decode messages ‘in depth’ by anagramming. A machine was built that automatically printed the Baudot traffic in Hollerith/IBM cards and these were searched for repeats but with limited success.
The intercepted messages contained reports on Soviet and German military dispositions, statements by POW's, signal intelligence reports, reports for TASS and SOVINFORMBUREAU, letters concerning postings, transfers, promotions, weather situation reports and supply manifests.
Information from the War Diary of Inspectorate 7/VI
More details are available from the monthly reports found in the War Diary of Inspectorate 7/VI.
In July 1943 a report by dr Pietsch says that the examination of Russian Baudot material revealed cipher teleprinter traffic and an effort was made to copy this traffic either by LNA (Leitstelle der Nachrichtenaufklärung in Loetzen) or Staats (Wa Pruef 7/IV C). Processing was to be carried out at Referat 13:
(2) Die eingehende Beobachtung der Baudot-Aufnahmen ergab, daß neben normalen Klar- und Chitexten auch Material anfällt, daß als eigentlicher Fernschreibschlüsselverkehr anzusprechen ist. Es wurden Maßnahmen verabredet, um das Material in einer zur Bearbeitung geeigneten Form (Lochstreifen, Einbeziehung des Verständigungsverkehrs) nach Berlin zu bekommen. Eine tiefergehende Bearbeitung dürfte nur an Ort einer Empfangsstelle (LNA oder Staats) möglich sein. Ob man jedoch beim Fehlen jeder Geräte-Kenntnis über primitive Feststellungen hinauskommen kann, bleibt abzuwarten. Über die weitere Entwicklung wird Referat 13 berichten.
In August ’43 the tapes with the Baudot traffic were examined but investigations could not be carried forwards due to the limited traffic and the many errors due to bad reception.
In September ’43 dr Pietsch and dr Doering (head of Referat 13) met with their Forschungsamt counterparts Councilors Paetzel and Kroeger (the FA’s cipher machine specialist), to discuss the Soviet cipher teleprinter problem.
Investigations continued and in November ’43 the analysts of Referat 13 succeeded in solving a long message and recovering the pure ‘key’:
6. Russischer Baudot--‐Verkehr. Es gelang, für einen längeren Spruch den reinen Schlüssel zu erstellen und damit den Geheimtext zu lösen. Schlussfolgerungen über den Bau und die Wirkungsweise der Schlüsselfernschreibmaschine konnten bisher nicht daraus gezogen werden.
In December ‘43 the departments were renamed, with Referat 13 becoming Referat b2. A second message was solved and investigations continued:
6. Russischer Baudot--‐Verkehr. Aus einem zweiten Spruchmaterial wurde stückweise der reine Schlüssel ermittelt. Weitere Materialen wurden laufend untersucht.
In February and March ’44 departments b1 (general research into cipher machines) and b2 (former 13) worked on the teleprinter problem, examining the Soviet 4-letter and 5-letter Baudot traffic and the movement of the cipher wheels of the device:
3. Russischer Baudot--‐Verkehre: Neu in Angriff genommen wurde die Untersuchung von russischen 4B--‐ und 5B--‐Sprüchen, die in Baudot--‐Fernschreibverkehren auftreten. Die Untersuchungen befinden sich noch im Anfangsstadium.
5. Russischer Baudot--‐Verkehr: Die Untersuchungen über die gegenseitige Abhängigkeit der einzelnen Impulse des reinen Schlüssels wurden an weiterem Spruchmaterial fortgesetzt.
In April ’44 department b1 stated that through analysis of the indicator groups the Soviet Baudot traffic could be subdivided into three distinct groups. The first being probably a cipher machine unlike the second and the third unclear:
3. Russischer Baudot--‐Verkehre: Durch Kenngruppenuntersuchungen gelang Trennung des Materials in drei Gruppen, von denen die erste im Gegensatz zur zweiten möglicherweise von einer Maschine stammt, während das dritte Verfahren völlig ungeklärt ist.
The report of department b2 shows that there was a meeting at Wa Prüf 7 to better organize the interception of this traffic. Investigations on the recovered pure key continued.
In the following months investigations continued but no breakthrough was achieved. There were complaints about the limited traffic intercepted.
In December ’44 four messages in depth were solved and pure key analyzed:
Russische Baudot verkehre
Aus dem anfallenden material könnte ein kompromiss von 4 phasengleichen sprüchen gefunden werden, der zum grössten Teil gelöst wurde. Mit Untersuchungen am reinen schlüssel wurde begonnen.
In January ’45 investigations of the recovered pure key continued and in February more in depth messages were solved:
Russische Baudot verkehr
An der lösung weiterer phasengleicher sprüche wurde gearbeitet; ausserdem wurden die untersuchungen am reinen Schlüssel fortgesetzt.
The last report, of March ’45 says that investigations continued:
Russische Baudot verkehr
Die untersuchung der russischen Baudot-verfahren wurde fortgesetzt.
The Poets series cipher machines
In the immediate postwar period the Anglo-Americans were able to solve at least two Soviet cipher teleprinters. These were given the names Coleridge and Longfellow.
Coleridge was used on military networks in the European part of the Soviet Union. By March 1946 it had been solved. The Coleridge decrypts provided important intelligence about the Soviet military’s order of battle, training activities and logistical matters.
The other system, Longfellow, was reconstructed by July 1946 and the settings were first retrieved in February 1947.
It seems both machines were ‘lost’ in 1948 when the Soviets introduced emergency changes in their cryptologic systems.
It is not clear if Coleridge and Longfellow had a connection with the cipher machines that the Germans attacked during the war.
Coleridge may have been the system the Germans called ‘Bandwurm’.
From TICOM I-2 ‘Interrogation of Dr. Huettenhain and Dr. Fricke at Flenshurg,21 May 1945’, p2
... they also have another machine„ funkfernschreiber, which encodes during transmission. it uses the international five impulse teleprinter code.
Q. Did the Russians use this machine much?
A. It became increasingly important during the last 1 1/2 years.
Q. What units used it?
A. Only the highest staffs, press and diplomatic services.
From TICOM DF-240 ‘Characteristics, Analysis and security of cryptographic systems’ - Parts III and IV, p37-39
Both texts indicated the pauses in transmission by - - - - - etc. The cipher tape has the peculiarity that in passing from the preliminary call-up to the transmission pause, the Russian letter Π, represented in the radio alphabet by + + + + +, occurs seven times.
Now since it was natural to assume that in this transition to and from cipher texts the same letter Π= + + + + + likewise appeared seven times in each case but vas no longer recognizable due to the encipherment the first and last seven cipher values of all cipher texts interrupted by transmission pauses were subjected to special study. Since the machine, once the daily key had been set up, was used very frequently during the course of the day for sending cipher text with numerous pauses in transmission without any new daily key being set up, rather numerous fragments of a length of seven letters were available at known intervals of greater or lesser lengths.
From this it could be concluded that the first seven and the last seven letters of each secret text came from enciphering the letter Π= + + + + + seven times and hence these fragments of cipher text represented pure key text. The following study of these fragments of pure key text led to a recognition of the fact that the first impulses show the same repeated picture in the chain of plus and minus impulses at an interval of 37, the second impulses at an interval of 39, the third impulses at an interval of 41, the fourth and fifth at an interval of 43 and 45 respectively (the intervals may have been 35, 37, 39, 41, 43). This showed the length of the five cipher wheels and their cam pattern according to the day’s setting. Each cam crest caused the inversion of the plain impulse into its opposite while a cam trough left a plain impulse unchanged. The wheels regularly moved one step after each cipher letter.
With this the decipherment of the cipher text had been accomplished. The reconstruction of the cam pattern of the wheels, which was set up new each day, was easily accomplished.
From TICOM DF-241 ‘The Forschungsamt’- Part I, p25
18. The Russian radio [2-channel] cipher machine with a channel for plain text and a channel for cipher text could be studied after the Technical Division had constructed a receiving device which at the same time removed the scrambling. The five elements of the radio alphabet [bands] ware enciphered singly through five wheels which move evenly. The wheels could be set up new each day corresponding to the daily key; but the period was constant and invariable. It was possible to solve this completely.
From TICOM DF-241 ‘The Forschungsamt’- Part IV, p38
It need only be mentioned here that the 2-channel cipher machine was withdrawn from use a few days after the Forschungsamt succeeded in solving it. When the machine was put into use again some weeks later, the cipher device of the cipher channel had been so altered that solution by the previous method was no longer possible since, when switching the machine from procedure traffic to cipher text and between a pause in transmission and cipher text, the switching became effective at once and the idling period of 7 elements had dropped out. That the same machine was involved was proven only by the receiver device which still broke up the scrambled text into a clear and a cipher text in the same manner as before. Because OKH had great interest in this traffic and its own receivers did not work perfectly, and because further detailed work at this time (Autumn 1943) in the Forschungsamt was not possible, OKH received all new traffic on this machine for processing.
From TICOM I-30 ‘Report on Interrogation of Uffz. Karrenberg at Steeple Claydon on 7th July 1945 at 11.00 am’, p2
The subject of this interrogation was confined to Karrenberg’s work on Russian Baudot letter ‘strip’, traffic known to the Germans as ‘BANDWURM’ and not to be confused with Russian 5-letter, traffic also carried on Baudot lines.
The Germans had not captured any of the apparatus used but considered that it consisted of two parts: 1) a Baudot-teleprinter with the letters of the Russian alphabet (excluding q and 'g') and figure and letter shift making 32 characters in all; 2) a cipher attachment consisting of 5 small wheels driven by one large wheel.
Each of the small wheels had a pattern of positive and negative impulses and each wheel worked in conjunction with one of the five impulses produced by pressing a key of the teleprinter, the effect being to add a positive or negative impulse to each of the five impulses produced by the letter being sent. This in effect means adding a letter of key to the clear letter to produce a cipher letter.
Depths were frequent on the traffic intercepted by the Germans, but they do not seem to have made any attempt to reconstruct the wheel patterns. In the case of the driving wheel they came to the tentative conclusion that it had a period of 43. The preambles of messages were always enciphered which resulted in stereotyped and known beginnings to messages. The machine setting for a message was indicated by means of a two figure number which presumably referred to a table of settings; a different table was used each day.
Before the actual start of a message a passage of operator's chat was sent enciphered by the addition of a constant letter to each letter of the clear text. This letter was then sent en clair- and repeated three times. The object of this was to see that the receiver had his machine net up correctly.
The system was used by the Army and Air Force and to a lesser extent by the N.K.W.D.
From TICOM I-153 ‘Second Interrogation of Uffz. Karrenberg of OKH on the Baudot-Scrambler Machine (Bandwurm)’, p2
P.W. stated that he believed the ‘Bandwurm’ traffic was first intercepted in 1940 in Warsaw. As far as he had been able to make out no interest had then been taken in it. The first actual knowledge we had of a traffic with the same external features (chat. indicators, eto.) was in summer 1943 when the first real interest was taken in it and the traffic was sent to Berlin for analysis. He understood that it went to a Dr. Pietsch and Doering.
There were a number of links usually varying according to the number of armies (Frontstaebe). The maximum number was 8. One end of each link was always in Moscow, the other would be mobile, and move with the armies. There were also one or two Airforce links. There was also supposed to be a link with the Far East. Traffic was heavier from the ‘outstations’ to Moscow.
and page 3
In Autumn 1944 both the end of 'adder' and every pause in the cipher proper was preceded by seven key letters [redacted]. Then the traffic went off the air and reappeared in December with no external change except that the seven ‘residue' letters had been reduced to three, suggesting a modification of the machine. In general it is clear that some of the features of the key at least have not changed in the last nine months.
From TICOM I-64 ‘Answers by Wm. Buggisch of OKH/Chi to Questions sent by TICOM’ , p2-3
1. Russian Systems
In 1943 B heard that the Forschungsamt (no individual names given) had claimed some success on a Russian teletype machine, and had re-created the action of the machine. It was a machine with a very long cycle being not prime but the product of several smaller cycles--like the SZ42. B. did not know the cycle of all of the individual wheels or any other details. He heard this from DOERING, who was then doing his research on the T-52, but liaison with the FA was bad anyway (Major Mettig was particularly opposed to the SS taint) and the next he heard was that the traffic found by the FA had stopped. B. remembered only that the cycle of one wheel was 37; the others, he thought, varied widely from 30-80.
Late in 1943 and increasingly in 1944 OKH itself began to intercept non-Morse, 5-impulse traffic (called ‘Hughes’ by B.). The Mathematics Referat went to work on it, with TROEBLICHER playing a leading part. At the end of 1943 the Russians created a ‘kompromiss’, giving a depth of about 8 messages with the same setting. With this they were able to recover 1400 letters of pure key and at the same time to ascertain that the traffic being passed was the 5-figure code, with regular station chat enciphered at the same time on the machine (Suggests a machine in constant motion as described by Karrenberg).Part of the depth was created within the same long message, so that the machine had a cycle, at least in this one case of about 1450 letters. The actual number was thought to be very significant by the Germans, as it was prime and so could not be the product of smaller cycles in any way that they could imagine. This differentiated it from the machine which the FA had broken. The Germans postulated either a single tape machine like the T43 or a machine in which the motions of the wheels influenced each other,1 and 2 affecting 3, 3 affecting 5, etc. as in the T52. They were never able to prove one theory or the other. (B. apologized for this. Said they did not have enough mathematicians to tackle the fascinating problem of determining what the motion must be to create this cycle. Seemed quite convinced that there would be a unique solution to the problem.) After this experience they devised Hollerith machinery to locate depths, but in fact they only found three or four more cases and none of these gave additional cycle evidence or even furnished as much pure key as the first one. B. left the section in June 1944. He thinks the traffic slumped off in the summer of 1944 and LNA took steps to try to improve the reception, as they believed the traffic was still there. TROEBLICHER was detailed to this end of the work at this time. B. stressed one fact which had surprised him, that they had never had information about either of these machines (he assumed that the one the FA broke was not the same because of the difference on cycles.) from PW or agent sources.
B. said in passing that their own security idea on the subject of wheel machines of this sort was that the cycle should not be the product of smaller periods(as in Hagelin) even if this was long. Mutual influence of wheels should be used to avoid this, but at the same time care must be taken that too short a period was not created in the process. This in fact had apparently been done by the Russians, but the fact that it was not repeated suggested to him that they might have seen the weakness and corrected it.
Troeblicher is mentioned in CSDIC (U.K.) SIR 1717, appendix A as Troebliger (Uffz). He worked in Group IV, Referat 1b as an analyst on Russian Baudot traffic.
Sources: CSDIC (U.K.) SIR 1717, SI-32 ‘Special intelligence report’, ‘European Axis Signal Intelligence in World War II’ vol2 and vol4, TICOM reports I-2, I-64, DF-98, I-30, I-153, I-169, I-173, DF-240, DF-241, ‘The Secret Sentry: The Untold History of the National Security Agency’, Intelligence and National Security article: ‘Behind Venona: American signals intelligence in the early cold war’, Soviet cryptographic service 1920-1940 , Kriegstagebuch Inspectorate 7/VI
Acknowledgments: It was Frode Weierud who first pointed to me the German interest in the Soviet teleprinter and the characteristics of the machine solved by the Forschungsamt in 1943. Credit also goes to Randy Rezabek for finding and uploading to the internet the interrogations of Karrenberg since they contain lots of information on the cipher machine.


Early Care & Education
Early care and education programs are crucial to a thriving economy, not only because they allow parents to work, but because the child care sector is large and purchases numerous goods and services. New economic development strategies toward enhancing child care access can improve child care financing and the business infrastructure associated with the child care sector.Additionally, significant investments in children’s well-being in the early years has enormous long-terms payoffs. Yet, quality early care and education supports in the U.S. are expensive and difficult to find, especially when compared with other developed nations.
Student parents make up 26 percent of community college students and many have young children, yet IWPR's research "how-to" manual demonstrating how other states can adapt the model to serve their specific policy needs.that child care available only meets a tiny fraction of the need. Improving child care access is not only about improving access to sources of care and education outside the home, but also requires increasing parents' ability to care for their own children. Significant investments in children's well-being in the early years has enormous long-term payoffs. IWPR has worked both national and state levels—in California, Kansas, Illinois, and the District of Columbia—to the costs of implementing early care and education expanses. IWPR also developed a
IWPR’s work on Early Care and Education addresses:
- Strategies for improving access to quality, affordable child care;
- The need to integrate a range of family supports into a comprehensive early childhood system;
- The economic development benefits of strengthening the early childhood sector;
- System-building approaches, and costs and benefits involved with early childhood expansions; and,
- The importance of improving job quality among early childhood educators.
Education and Training, IWPR
Visit our external resources page for links to more information on this topic.
Latest Reports from IWPR
High Skill and Low Pay: The Economics of Child Care Work
In the midst of a debate over the cost and quality of child care and the appropriate public role in its provision, this paper documents the current situation of child care workers. Using available data from the Census Bureau, the Bureau of Labor Statistics, and numerous salary surverys conducted by a variety of groups across the country, it describes who child care workers are, in terms of their gender, race, age, and education; the job titles, occupations, and settings in which they work; and the wages and benefits they receive.
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Wages of Salaries of Child Care Workers: The Economic and Social Implications of Raising Child Care Worker's Salaries
Testimony before the Subcommittee on Children, Drugs, and Alcoholism, Committee on Labor and Human Resources, U.S. Sebate, Washington, DC. Describes who are the child care workers, their salaries, reasons the salaries are so low, and teh effects of low salaries. Available by mail in limited quantities. E-mail iwpr [at] iwpr [dot] org to place an order.


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This page links to very brief summary data on the hominid fossils most likely to be of importance in any introductory course involving a small amount of human paleontology (including UCSD's MMW-11). For the most part, each species is on a separate page and includes a picture of a cast of a skull and, where available, a drawing or a picture of a waxwork reconstruction.
Some scholars differentiate a subfamily called homininae ("hominines" or "hominins") to refer to these specimens, reserving the family name hominidae ("hominids") for broader range of species than previously, including chimps and gorillas. Since all hominin(e)s are hominids anyway, that term is ignored here. (Click here for a table showing the organization of classification categories.)
A very brief glossary linked to the top of each page opens in secondary window. Except on this page, terms found in the glossary are underlined with small blue dots. They are not links —the link to the glossary is at the top of each page— but a brief definition will appear if you hold your mouse over them.
Two review quizzes are available for this material, Normal and Hero.
Students in MMW-11 are invited to use additional materials on a password-restricted page, Developments in Hominid Paleontology.
This set of materials takes its inspiration from a "Hominid Guide" devised by Dr. Nancy J. Friedlander in 1990 for use in the first quarter of "Making of the Modern World," a world-civilization sequence in Eleanor Roosevelt College, UCSD. The present text is differently organized, newer, and much shorter. I have also added pictures. But the goal of an easily accessible, reasonably masterable introductory overview of the hominid fossil record for the convenience of beginning college students remains. I am most grateful for Dr. Friedlander's advice and assistance as I have sought to take account of changing information and new interpretive trends.
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Recently a local reading group I attend reviewed Ayn Rand’s dystopian novelette Anthem. That book served as my introduction to Rand many years ago, and rereading it proved rewarding.
In our discussion, we explored a variety of topics:
* The romance between the two lead characters, Equality and Liberty, develops as Equality becomes an independent thinker and scientist. This anticipates Howard Roark’s comment in Fountainhead, “To say ‘I love you’ one must first know how to say the ‘I’.”
* The way Equality values his scientific work anticipates the relationship between the heroes and their work in Atlas Shrugged. It illustrates Rand’s view that material objects are not valuable in themselves, but only in relation to individual values and consciousness.
* For Rand, totalitarianism necessarily results, ultimately, in total economic collapse. The central reason for this is that political controls prevent individuals from acting on their own reasoned judgment, ultimately chilling reasoned thought as such. In the long run capitalism and technological progress cannot survive totalitarian controls. Contrast the primitive society of Anthem with the (in some ways) highly technical societies of other dystopias, such as Brave New World and, more recently,Hunger Games.
Below are the review questions used for our group (and others are free to reproduce these for purposes of discussion).
1. What is the ego? (Peikoff’s 1994 introduction)
2. How do the conditions surrounding the writing and publication of Anthem relate to the book’s theme? (Peikoff’s 1994 introduction, Rand’s 1946 foreword)
3. What are the principles and laws of the story’s society, and what are the emotional consequences of Equality 7-2521 breaking them? (Chapter I)
4. What is the connection between the collectivism and the technological regression of the story? (Chapter I)
5. Why does Rand place the budding romance between the discovery of the tunnel and the Unspeakable Word? (Chapter II)
6. What is the relationship between the advancing scientific discoveries and the building romance? (Chapter III, Chapter IV)
7. Why does Equality say “our new power defies all laws?” Is he right? (Chapter IV)
8. Why does Equality think “this wire is as a part of our body?” (Chapter V)
9. Why does Equality believe the Council of Scholars will accept his gift? Why is he wrong? (Chapter V, Chapter VII)
10. What is the significance of the observation that the electric light “would bring ruin to the Department of Candles?” (Chapter VII)
11. How does Equality’s self-discovery connect to his love of the Golden One? (Chapter VIII, Chapter IX)
12. How does Equality’s independence mesh with the Golden One’s deference toward him? (Chapter X)
13. What is the “world ready to be born?” (Chapter X)
14. What does Equality mean when he writes, “I am the warrant and the sanction?” (Chapter XI)
15. What does Equality mean when he writes, “I ask none to live for me, nor do I live for any others?” (Chapter XI)
16. How does Prometheus retain his independence while learning so much from others? (Chapter XII)
17. How can one man stoke “the spirit of man?” (Chapter XII)


Through the eyes of a child investigating the aspects of society that matter to them, this title takes a visual approach to the study of the important periods for Key Stage 2 history. It includes details of where and how these civilisations lived and asks us to imagine themselves in a particular time and era. It is useful for readers aged 6-8.
- Limba : Engleza
- Data Publicarii : 25 May 2005
- Format : Paperback
- Numar pagini : 32
- ISBN : 9781844432929


Benefits of RCC construction over brick and mortar buildings
Feb-09-2018 Post / benefits-of-rcc-construction-over-brick-and-mortar-buildings
Benefits of RCC construction over brick and mortar buildingsTMT Steel Rods
It is the 21st century, and RCC constructions have replaced traditional brick and mortar style of buildings for most constructions. RCC stands for Reinforced Cement Concrete, which has steel cores, around which the cement-concrete matrix is poured. Bricks and mortar constructions are made with using bricks fixed to a mixture of cement, sand and water through masonry. Due to the vast technological difference in these building techniques, RCC holds obvious utilitarian profit over mortar based brickworks.
Here are a few advantages of using RCC as a building material over brick and mortar constructions:
- Load bearing path and capacity: RCC constructions have a longer load bearing path due to its strong Steel core while the brick structures lack this strength. When the load is multiplied for construction of higher stories, or during seismic activity, RCC constructions are practically better resilient due to their strength. This strength is multiplied due to high-quality TMT Steel rods that reinforce the cement concrete mixture. Even blocks survive better than the bricks. The mortar has to be replaced in every 5-10 years depending on exposure to moisture, loads and impacts. The RCC constructions can thus bear the loads for a large number of stories, compared to brickworks due to high load-bearing capacity.
- Versatile Structures: The actual size of a construction is measured by the square inch area of the indoor rooms. The columns bear most of the weight, so it’s possible to minimize the number of walls in RCC, and even large halls or auditoriums are effortlessly constructed. Brickworks needs walls that bear their loads and thus results in smaller rooms’ size. Developments in lifestyle choices, construction industry, and commercial sector have resulted in preference to RCC for the same benefit of larger spaces and customized structures.
- The depth of foundation: Brickworks need deeper trenches as a foundation to achieve better stability for their structures. RCC need lesser excavation for inserting TMT steel rods as reinforcements are over the ground, with a concrete cement mixture. This is because of the superior grip of TMT rods over concrete, then mortar has over brick. The lower brickworks also degrade over time, resulting in weaker bases and eventual failures.
- Costs: Brickworks are cheaper compared to RCC if constructed for 2 stories or less. But overall costs including skilled labour, material costs, and wall areas result in an expensive construction for brick and mortar. The longevity of the RCC buildings makes them a cost-effective option in the long run.
- Durable and Reliable: With the sturdiness of the Steel centre, RCC forms stronger bonds that stand strong during a catastrophe or tragic calamities. Brick and mortar structures have the deficit of a stronger core and bond that can withstand strong forces, therefore making them less reliable. RCC constructions are therefore more durable and reliable for life and property.
These are few of the many reasons why RCC constructions are slowly rendering brickworks extinct and only used for aesthetic appeal. The RCC is the future of construction technology, with a rapidly transforming industry to backbone its promises. India’s construction industry is a large contributor to its rising GDP and economy, and exports steel, cement, finished products, etc. Agni Steels’ is a proud manufacturer of high-quality TMT Steel rods and rebars, to strengthen the RCC constructions throughout South India. We hope to continue our service of providing strong steel bars at competitive prices for our valued customers.


The shortest distance from the East to West Coast would be 2,092 miles (3,347 km) from San Diego, CA to Jacksonville, FL.
Geography of California
West Coast most often refers to coastline which is on the western side of a particular area. Many other terms refer to this initial meaning. Some of these things include:
Geography of the United States
Covering an area of 163,696 sq mi (423,970 km2), California is geographically diverse. The Sierra Nevada, the fertile farmlands of the Central Valley, and the arid Mojave Desert of the south are some of the major geographic features of this U.S. state. It is home to some of the world's most exceptional trees: the tallest (coast redwood), most massive (Giant Sequoia), and oldest (bristlecone pine). It is also home to both the highest (Mt. Whitney) and lowest (Death Valley) points in the 48 contiguous states.
The state is generally divided into Northern and Southern California, although the boundary between the two is not well defined. San Francisco is decidedly a Northern California city and Los Angeles likewise a Southern California one, but areas in between do not often share their confidence in geographic identity. The US Geological Survey defines the geographic center of the state at a point near North Fork, California.
The United States is a country in the Northern Hemisphere, Western Hemisphere, and the Eastern Hemisphere. It consists of forty-eight contiguous states in North America, Alaska, a peninsula which forms the northwestern most part of North America, and Hawaii, an archipelago in the Pacific Ocean. There are several United States territories in the Pacific and Caribbean. The term "United States", when used in the geographical sense, means the continental United States, Alaska, Hawaii, Puerto Rico, Guam, and the Virgin Islands of the United States. The country shares land borders with Canada and Mexico and maritime (water) borders with Russia, Cuba, and the Bahamas in addition to Canada and Mexico.
Jacksonville is the largest city in the U.S. state of Florida by population and the largest city by area in the contiguous United States. It is the county seat of Duval County, with which the city government consolidated in 1968. Consolidation gave Jacksonville its great size and placed most of its metropolitan population within the city limits; with an estimated population in 2012 of 836,507, it is the most populous city proper in Florida and the Southeast, and the 12th most populous in the United States. Jacksonville is the principal city in the Jacksonville metropolitan area, with a population of 1,345,596 in 2010.
Jacksonville is in the First Coast region of northeast Florida and is centered on the banks of the St. Johns River, about 25 miles (40 km) south of the Georgia state line and about 340 miles (550 km) north of Miami. The Jacksonville Beaches communities are along the adjacent Atlantic coast. The area was originally inhabited by the Timucua people, and in 1564 was the site of the French colony of Fort Caroline, one of the earliest European settlements in what is now the continental United States. Under British rule, settlement grew at the narrow point in the river where cattle crossed, known as Wacca Pilatka to the Seminole and Cowford to the British. A platted town was established there in 1822, a year after the United States gained Florida from Spain; it was named after Andrew Jackson, the first military governor of the Florida Territory and seventh President of the United States.
San Diego / / is a major city in California, on the coast of the Pacific Ocean in Southern California, approximately 120 miles (190 km) south of Los Angeles and immediately adjacent to the border with Mexico. San Diego is the eighth largest city in the United States and second largest in California and is one of the fastest growing cities in the nation. San Diego is the birthplace of California and is known for its mild year-round climate, natural deep-water harbor, extensive beaches, long association with the U.S. Navy, and recent emergence as a healthcare and biotechnology development center. The population was estimated to be 1,322,553 as of 2012.
Historically home to the Kumeyaay people, San Diego was the first site visited by Europeans on what is now the West Coast of the United States. Upon landing in San Diego Bay in 1542, Juan Cabrillo claimed the entire area for Spain, forming the basis for the settlement of Alta California 200 years later. The Presidio and Mission of San Diego, founded in 1769, formed the first European settlement in what is now California. In 1821, San Diego became part of newly independent Mexico, and in 1850, became part of the United States following the Mexican-American War and the admission of California to the union.
First Coast Commuter Rail
Southern California, often abbreviated as SoCal, is a megaregion or megapolitan area in the southern portion of the US state of California. Large urban areas include the Greater Los Angeles, and Greater San Diego. The region stretches along the coast from about Santa Barbara to the United States and Mexico border, and from the Pacific Ocean inland to the Nevada and Arizona borders. The heavily built-up urban area stretches along the coast from Ventura, through the Greater Los Angeles Area, the Inland Empire and down to San Diego. Southern California is a major economic center for the state of California and the United States.
Southern California's population encompasses eight metropolitan areas, or MSAs: the Los Angeles metropolitan area, consisting of Los Angeles and Orange counties; the Inland Empire, consisting of Riverside and San Bernardino counties; the San Diego metropolitan area; the Bakersfield metropolitan area; the Oxnard–Thousand Oaks–Ventura metropolitan area; the Santa Barbara metro area; the San Luis Obispo metropolitan area; and the El Centro area. Out of these, three are heavy populated areas: the Los Angeles area with over 12 million inhabitants, the Riverside-San Bernardino area with over 4 million inhabitants, and the San Diego area with over 3 million inhabitants. For CSA metropolitan purposes, the five counties of Los Angeles, Orange, Riverside, San Bernardino, and Ventura are all combined to make up the Greater Los Angeles Area with over 17.5 million people. With over 22 million people, southern California contains roughly 60% of California's population.
Race Across America
The First Coast Commuter Rail is a proposed commuter rail system serving Jacksonville, FL and northeast Florida. It is currently in the very early planning stages, having completed the first step of a fesibility study and currently pursuing an alternatives analysis.
west coast of united states
The Race Across America, or RAAM, is an ultramarathon bicycle race across the United States that started in 1982 as the Great American Bike Race.
RAAM is among the best-known and longest annual endurance events in the world. All entrants must prove their abilities by competing in any of several qualifying events, completing a course within a specified time period. RAAM is sanctioned by the UltraMarathon Cycling Association (UMCA).


STATUS IN THE WILD: Least Concern
RANGE: South America
PHYSICAL FEATURES AND CHARACTERISTICS
Black howler monkeys are one of the few primate species that have sexual dimorphism, which means that the males and females have different coat colors. The males have a black coat, while the females are blonde. Juveniles of both genders will also appear blonde until they reach sexual maturity. These primates have a prehensile tail that has no hair on the bottom side; this helps them grasp onto branches during locomotion. They have five fingers and five toes, which also help when climbing. They typically weigh between fifteen and twenty-two pounds and are around two to three feet in height. The males are usually taller and heavier than the females.
Their upper molars have sharp, shearing crests that are used to grind leaves. Howler monkeys, like all monkeys from the Americas, have nostrils that are far apart and sideways-facing, whereas African monkeys have nostrils that are close together and point in the same direction. Their hyoid bone (Adam’s apple) is enlarged, which restricts some of their arm movement and makes them rely even more on their tail for locomotion.
They are named after their vocalizations and can be heard most often around sunrise. The “dawn chorus” sounds more like roaring than howling and announces the howler’s position to other howlers. This call can be heard up to three miles away. The males have large throats that are specialized, with shell-like vocal chambers that allow their call to be heard far away.
LIFESTYLE AND REPRODUCTION
Male members of the group wake each morning at dawn with a “chorus” that is answered by other males. Since the howlers do not have exclusive territory and share parts of their range with others, this morning call helps them defend, define, and clarify the group’s home range. The weaker troops can identify the strong troops and avoid those areas while looking for food. These troops are usually between ten to twenty monkeys, with more females than males. When two different howler groups meet, they use a lot of energy in howling, leaping, running, and fighting. In order to not waste too much energy, the males spend a lot of time howling to defend their range.
Howlers spend a lot of their day resting. Because they can only extract limited calories from their food, they have to be very cautious about how much energy they use. They do not like to jump from tree to tree and prefer to always have a hand, tail, or foot holding onto a tree as they reach to the next tree. They have been seen linking together hand-to-tail with multiple monkeys in order to make a bridge for the young howler monkeys to cross. Males handle all the disputes and defend the group from various predators. This allows the female to spend more time and energy on reproduction and caring for the young.
Females typically give birth every other year, resulting in one offspring after a one hundred eighty day gestation period. The young will reach sexual maturity around eighteen months of age. Tongue flicking is a ritualized display of sexual solicitation. Their tongue is pink with black bordering, which makes it easy to spot.
Black howler monkeys can be found in southern Brazil, Paraguay, eastern Bolivia, and northern Argentina. Since they do not have to travel far to find leaves, they stay in a small home range for most of their life.
Howler monkeys spend almost all of their time in trees. They can be found in primary, arid deciduous, and broadleaf forests.
These primates are herbivores, mainly consuming tree vines, leaves, flowers, and tropical forest fruits. Howlers mainly eat leaves and greens, and spend little time eating the flowers and fruit since they are less abundant. When available, they will sometimes eat the eggs from birds’ nests. They get all their liquid they need from their fruits and plants; therefore, they are seen drinking little water.


The former Trakehnen is now situated in the Russian part of the former East Prussia and is called Yasnaya Polyana.
One year after the border opening in 1992 more than 60,000 visitors came to Kaliningrad, the former Koenigsberg, to see “Trakehnen”. For more than four decades this hadn’t been possible and the yearning was strong. There are no horses left in Yasnaya Polyana and the compounds of the former main stud farm, once rich in tradition, are threatened to fall apart after their more than 250 year long history. But the myth of the former stronghold of horse breeding still enchants horse and history aficionados alike.
It is the declared aim of the Association of friends and patrons of the former Trakehnen main stud farm to preserve two significant historic buildings. By means of contributions and membership fees alone the Association tries to save Trakehnen from falling into ruins. In accordance with the local population and the Russian authorities the cultural heritage is to be preserved. Thanks to the active support and help of many friends of Trakehnen the foundation walls could be dried and eaves and downspouts were replaced. The back of the Equerry’s house was renovated and freshly painted. Two museum rooms have been installed in the eastern wing and also the Trakehnen gate shines anew. Since the end of the 1940s a Russian school has been using the Equerry’s house.


German mathematician and instrument-maker. In 1518, during a visit to Italy, struck up a friendship with Andreas Copernicus, Nicolaus's brother. Hartmann sought to measure magnetic declination, for which he computed relatively good approximations in several localities including Nuremberg and Rome. Made many high-quality mathematical instruments including sundials, astrolabes, globes, armillary spheres, and astronomical compendia, but also military instruments such as gunner's calipers. In 1533, published a manual on the construction of diptych dials. Other, unpublished works contain drawings of scientific instruments such as sundials and astrolabes.


The Food Systems Project works to increase residents’ access to healthy, affordable food while educating residents about ways to eat healthy.
Garden-Based Nutrition Education
The Food Systems Project offers a school garden based nutrition education program that partners with four Lansing schools to provide quality, effective nutrition education programming for elementary aged students (5-12 years old). Our program offers several components: in-school classroom lessons, an after-school garden club, a summer garden camp program, and community-based food sampling. These three programs reach over 1,000 students in grades K-6, working to promote healthy habits and increase student’s consumption of fresh fruits and vegetables!
We partner with four Lansing schools: Riddle Elementary, Willow Elementary, Gier Park School and Sheridan Road School. Each partner school has a garden which is used as an educational tool to teach students about growing, harvesting and preparing healthy, nutritious food! Students are engaged in the school gardens in many ways, participating in every step from choosing what to grow and preparing the soil, to harvesting, cooking, and eating the food. We visit over 40 classrooms for 1 hour visits each month


Azaleas, with their stunning and vibrant blooms, hold a special place in the hearts of garden enthusiasts and nature lovers alike. These beautiful flowering shrubs have captivated people for centuries with their colorful displays and delicate petals. However, to fully appreciate the spectacle of azaleas in full bloom, it is essential to understand when these enchanting flowers come to life. In this article, we will delve into the fascinating world of azalea blooming, exploring the factors that influence their flowering patterns and discovering the optimal times to witness their breathtaking beauty. Whether you’re an avid gardener or simply an admirer of nature’s wonders, join us as we uncover the secrets of when azaleas bloom.
When Do Azaleas Bloom?
Azaleas typically bloom in the spring season, although the exact timing can vary depending on factors such as climate, location, and specific azalea varieties. In general, early-blooming azaleas can start flowering as early as late winter or early spring, while mid-season varieties typically bloom in mid to late spring. Late-blooming azaleas can extend the blooming season into early summer. It’s important to note that specific regions and microclimates can influence the exact timing of azalea blooms. To get a better understanding of when azaleas bloom in your area, consult gardening resources specific to your location or reach out to local horticultural experts for guidance.
How Do Different Climate Zones Affect The Blooming Time Of Azaleas?
Different climate zones have a significant impact on the blooming time of azaleas. The primary factors influenced by climate zones include temperature, winter hardiness, and the length of the growing season. Here’s a breakdown of how different climate zones affect the blooming time of azaleas:
Cold Climate Zones:
In colder climates, where winters are harsh, and temperatures drop below freezing, azaleas often enter a dormant phase. They require a certain number of chilling hours to break dormancy and initiate blooming. Springtime bloom is delayed in cold climate zones due to prolonged winter conditions.
Temperate Climate Zones:
Temperate climate zones, characterized by mild winters and moderate temperatures, offer favorable conditions for azaleas. They typically bloom in spring when temperatures warm up, and frost risk diminishes. Spring-flowering varieties are well-suited to temperate regions.
Warm Climate Zones:
In warm climate zones, where winters are mild, and temperatures rarely reach freezing levels, azaleas may bloom earlier or have an extended blooming period. These regions, such as the southern United States, can experience azalea blooms as early as late winter or early spring.
Mediterranean Climate Zones:
Mediterranean climates, characterized by mild, wet winters and hot, dry summers, can support azalea growth and bloom. Azaleas in these regions often bloom in the spring season when temperatures are moderate and moisture is available. However, careful water management is necessary during the dry summer months.
The Relationship Between Temperature And The Blooming Cycle Of Azaleas.
Temperature plays a crucial role in the blooming cycle of azaleas. Here’s an overview of the relationship between temperature and the blooming cycle of azaleas:
Chilling Requirements: Azaleas, like many other plants, have specific chilling requirements. They need a certain number of cumulative hours of exposure to cool temperatures (typically between 32°F to 45°F or 0°C to 7°C) during their dormant period to break dormancy and promote blooming. This chilling period allows the plant to undergo necessary physiological changes and prepare for the upcoming blooming season.
Bud Development: After the chilling requirement is met, azalea buds develop. The timing and duration of bud development depend on the temperature conditions. Warmer temperatures stimulate faster bud development, while cooler temperatures slow down the process. Optimal temperatures for bud development usually range between 45°F to 55°F (7°C to 13°C).
Bloom Initiation: Once the buds have developed, azaleas require a specific temperature range to trigger blooming. For most azalea varieties, temperatures between 55°F to 65°F (13°C to 18°C) are conducive to bloom initiation. Warmer temperatures can accelerate blooming, while cooler temperatures may delay it.
Flowering: As the buds transition into flowers, temperature conditions continue to influence the duration and intensity of blooming. Mild temperatures within the preferred range (around 60°F to 70°F or 15°C to 21°C) are ideal for promoting vibrant and prolonged blooming. Extreme heat or cold spells can negatively impact blooming, leading to shorter durations or less impressive flower displays.
Azalea Bloom Periods By Region
Azalea bloom periods can vary by region due to differences in climate, temperature, and local growing conditions. Here’s a general overview of azalea bloom periods based on different regions:
In Northern regions with colder climates, such as northern parts of North America, Europe, or Asia, azaleas typically bloom later in the spring. Blooming may occur from late spring to early summer, depending on the specific variety and local weather conditions. These regions often experience delayed blooming due to extended winter conditions and a shorter growing season.
In temperate regions with moderate climates, including many parts of North America, Europe, and Asia, azaleas tend to bloom during the spring season. The bloom is generally in mid to late spring, around April to May, when temperatures are milder and frost risks decrease. This is when a wide range of azalea varieties showcase their vibrant flowers.
In southern regions with warmer climates, such as the southern United States, parts of Australia, or Southeast Asia, azaleas may bloom earlier and have an extended blooming period. Some azalea varieties can bloom as early as late winter or early spring, taking advantage of the milder winter conditions. Blooming can continue into spring and early summer, depending on the specific variety and local temperatures.
Mediterranean climates, found in areas like California, Southern Europe, or parts of South Africa, offer favorable conditions for azalea blooming. Azaleas in these regions often bloom in the spring season, similar to temperate regions. However, it’s essential to manage water availability during the dry summer months to support healthy blooming.
How To Prune Azaleas For Optimal Blooming?
- Prune azaleas immediately after they finish blooming. This allows the plant to recover and produce new growth before setting buds for the next season’s blooms. Pruning at the wrong time, such as fall or winter, can remove potential flower buds and reduce blooming.
- Start by removing any dead, damaged, or diseased branches. Cut them back to healthy tissue, making clean cuts just above a leaf node or bud. This helps maintain the overall health of the plant and improves air circulation, reducing the risk of diseases.
- Azaleas can become dense and overcrowded over time. Thin out the interior branches to improve light penetration and airflow within the plant. Remove some older, woodier branches, focusing on opening up the shrub’s center. This encourages new growth and enhances blooming potential.
- Azaleas can be pruned to maintain a desired shape and size. Use hand pruners or shears to trim long or unruly branches to a desired length. Take care not to remove more than one-third of the plant’s growth in a single pruning session to avoid stressing the azalea.
- While pruning is essential, avoid excessive or aggressive pruning, as it can reduce blooming. Azaleas form flower buds on old wood, so removing too many branches can eliminate potential buds for the next season’s blooms. Focus on selective pruning rather than extensive removal.
Pruning azaleas at the right time and with proper techniques is essential for optimal blooming. Remove dead or diseased wood, thin out overcrowded branches, and shape the plant to maintain its desired size and form. However, avoid over-pruning, as it can reduce future blooming potential. Remember to prune azaleas immediately after they finish blooming and be mindful of each variety’s specific growth habits. With careful pruning, you can help promote healthy growth, improve air circulation, and encourage abundant blooms in your azaleas.
Q: Can I prune azaleas during the blooming season?
A: It is generally recommended to avoid pruning azaleas during the blooming season. Pruning at this time can remove potential flower buds and diminish the current season’s blooms. It’s best to prune azaleas immediately after they finish blooming.
Q: How much can I prune off my azaleas?
A: When pruning azaleas, avoid removing more than one-third of the overall plant’s growth in a single pruning session. Removing excessive amounts of growth can stress the plant and reduce blooming potential. Focus on selective pruning to maintain the shape and size of the azalea while preserving its overall health.
Q: What tools do I need to prune azaleas?
A: For pruning azaleas, you will need a pair of sharp bypass hand pruners or shears. These tools will allow you to make clean cuts and minimize damage to the plant. Additionally, it may be helpful to have a pair of loppers for thicker branches or a pruning saw for larger pruning tasks.