1,841 research outputs found
A Survey on Computational Propaganda Detection
Propaganda campaigns aim at influencing people's mindset with the purpose of
advancing a specific agenda. They exploit the anonymity of the Internet, the
micro-profiling ability of social networks, and the ease of automatically
creating and managing coordinated networks of accounts, to reach millions of
social network users with persuasive messages, specifically targeted to topics
each individual user is sensitive to, and ultimately influencing the outcome on
a targeted issue. In this survey, we review the state of the art on
computational propaganda detection from the perspective of Natural Language
Processing and Network Analysis, arguing about the need for combined efforts
between these communities. We further discuss current challenges and future
research directions.Comment: propaganda detection, disinformation, misinformation, fake news,
media bia
Explicit description of twisted Wakimoto realizations of affine Lie algebras
In a vertex algebraic framework, we present an explicit description of the
twisted Wakimoto realizations of the affine Lie algebras in correspondence with
an arbitrary finite order automorphism and a compatible integral gradation of a
complex simple Lie algebra. This yields generalized free field realizations of
the twisted and untwisted affine Lie algebras in any gradation. The free field
form of the twisted Sugawara formula and examples are also exhibited.Comment: 24 pages, LaTeX, v2: small corrections in appendix
Adaptive structure tensors and their applications
The structure tensor, also known as second moment matrix or Förstner interest operator, is a very popular tool in image processing. Its purpose is the estimation of orientation and the local analysis of structure in general. It is based on the integration of data from a local neighborhood. Normally, this neighborhood is defined by a Gaussian window function and the structure tensor is computed by the weighted sum within this window. Some recently proposed methods, however, adapt the computation of the structure tensor to the image data. There are several ways how to do that. This article wants to give an overview of the different approaches, whereas the focus lies on the methods based on robust statistics and nonlinear diffusion. Furthermore, the dataadaptive structure tensors are evaluated in some applications. Here the main focus lies on optic flow estimation, but also texture analysis and corner detection are considered
Search for astrophysical sources of neutrinos using cascade events in IceCube
The IceCube neutrino observatory has established the existence of a flux of
high-energy astrophysical neutrinos inconsistent with the expectation from
atmospheric backgrounds at a significance greater than . This flux has
been observed in analyses of both track events from muon neutrino interactions
and cascade events from interactions of all neutrino flavors. Searches for
astrophysical neutrino sources have focused on track events due to the
significantly better angular resolution of track reconstructions. To date, no
such sources have been confirmed. Here we present the first search for
astrophysical neutrino sources using cascades interacting in IceCube with
deposited energies as small as 1 TeV. No significant clustering was observed in
a selection of 263 cascades collected from May 2010 to May 2012. We show that
compared to the classic approach using tracks, this statistically-independent
search offers improved sensitivity to sources in the southern sky, especially
if the emission is spatially extended or follows a soft energy spectrum. This
enhancement is due to the low background from atmospheric neutrinos forming
cascade events and the additional veto of atmospheric neutrinos at declinations
.Comment: 14 pages, 9 figures, 1 tabl
Book Reviews
With the observation of high-energy astrophysical neutrinos by the IceCube Neutrino Observatory, interest has risen in models of PeV-mass decaying dark matter particles to explain the observed flux. We present two dedicated experimental analyses to test this hypothesis. One analysis uses 6 years of IceCube data focusing on muon neutrino âtrackâ events from the Northern Hemisphere, while the second analysis uses 2 years of âcascadeâ events from the full sky. Known background components and the hypothetical flux from unstable dark matter are fitted to the experimental data. Since no significant excess is observed in either analysis, lower limits on the lifetime of dark matter particles are derived: we obtain the strongest constraint to date, excluding lifetimes shorter than s at 90% CL for dark matter masses above 10 TeV
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