Abstract:
  As more people flock to social media to connect with others and form virtual
communities, it is important to research how members of these groups interact
to understand human behavior on the Web. In response to an increase in hate
speech, harassment and other antisocial behaviors, many social media companies
have implemented different content and user moderation policies. On Reddit, for
example, communities, i.e, subreddits, are occasionally banned for violating
these policies. We study the effect of these regulatory actions as well as when
a community experiences a significant external event like a political election
or a market crash. Overall, we find that most subreddit bans prompt a small,
but statistically significant, number of active users to leave the platform;
the effect of external events varies with the type of event. We conclude with a
discussion on the effectiveness of the bans and wider implications for the
online content moderation.


Abstract:
  We isolate a new preservation class of Suslin forcings and prove several
associated consistency results in the choiceless theory ZF+DC regarding
countable chromatic numbers of various Borel hypergraphs.


Abstract:
  Extremely compact objects trap gravitational waves or neutrinos, assumed to
move along null geodesics in the trapping regions. The trapping of neutrinos
was extensively studied for spherically symmetric extremely compact objects
constructed under the simplest approximation of the uniform energy density
distribution, with radius located under the photosphere of the external
spacetime; in addition, uniform emissivity distribution of neutrinos was
assumed in these studies. Here we extend the studies of the neutrino trapping
for the case of the extremely compact Tolman VII objects representing the
simplest generalization of the internal Schwarzschild solution with uniform
distribution of the energy density, and the correspondingly related
distribution of the neutrino emissivity that is thus again proportional to the
energy density; radius of such extremely compact objects can overcome the
photosphere of the external Schwarzschild spacetime. In dependence on the
parameters of the Tolman VII spacetimes, we determine the "local" and "global"
coefficients of efficiency of the trapping and demonstrate that the role of the
trapping is significantly stronger than in the internal Schwarzschild
spacetimes. Our results indicate possible influence of the neutrino trapping in
cooling of neutron stars.


Abstract:
  Quantum computing provides a new way for approaching problem solving,
enabling efficient solutions for problems that are hard on classical computers.
It is based on leveraging how quantum particles behave. With researchers around
the world showing quantum supremacy and the availability of cloud-based quantum
computers with free accounts for researchers, quantum computing is becoming a
reality. In this paper, we explore both the opportunities and challenges that
quantum computing has for location determination research. Specifically, we
introduce an example for the expected gain of using quantum algorithms by
providing an efficient quantum implementation of the well-known RF
fingerprinting algorithm and run it on an instance of the IBM Quantum
Experience computer. The proposed quantum algorithm has a complexity that is
exponentially better than its classical algorithm version, both in space and
running time. We further discuss both software and hardware research challenges
and opportunities that researchers can build on to explore this exciting new
domain.