7,146 research outputs found
Continental Drift: Contextualizing Citizens United by Comparing the Diverging British and American Approaches to Political Advertising
There is perhaps no more vital an issue to a healthy democracy than its attitude towards political speech. Because political speech—and particularly political advertising—has a profound influence on the outcomes of elections, most vibrant democracies recognize the need to avoid arbitrary distinctions among political advertisers that might sway elections for reasons other than the popularity of the candidates. The First Amendment avoids arbitrary distinctions by ensuring a free and open marketplace of ideas in the political speech realm, with almost no restrictions on political advertising. The United Kingdom, by contrast, addresses the problem by way of an outright ban on political advertising. This Note explores the recent, and controversial, Citizens United decision in the context of avoiding such groundless distinctions. In particular, this Note compares the American approach to the British approach, and argues that Citizens United is a correct reaction, within American constitutional law and case law, to the problem of arbitrary distinctions in the political advertising realm
Molecular Clouds as the Origin of the Fermi Gamma-Ray GeV-Excess
The so-called "GeV-excess" of the diffuse Galactic gamma-ray emission is
studied with a spectral template fit based on energy spectra. The spectral
templates can be obtained in a data-driven way from the gamma-ray data, which
avoids the use of emissivity models to subtract the standardbackground
processes from the data. Instead, one can determine these backgrounds
simultaneously with any "signals" in any sky direction, including the Galactic
disk and the Galactic center. Using the spectral template fit two hypothesis of
the "GeV-excess" were tested: the dark matter (DM) hypothesis assuming the
excess is caused by DM annihilation and the molecular cloud (MC) hypothesis
assuming the "GeV-excess" is related to a depletion of gamma-rays below 2 GeV,
as is directly observed in the Central Molecular Zone (CMZ). Both hypotheses
provide acceptable fits, if one considers a limited field-of-view centered
within 20 around the Galactic center and applies cuts on the energy
range and/or excludes low latitudes, cuts typically applied by the proponents
of the DM hypothesis. However, if one considers the whole gamma-ray sky and
includes gamma-ray energies up to 100 GeV we find that the MC hypothesis is
preferred over the DM hypothesis for several reasons: i) The MC hypothesis
provides significantly better fits; ii) The morphology of the "GeV-excess"
follows the morphology of the CO-maps, a tracer of MCs, i.e. there exists a
strong "GeV-excess" in the Galactic disk also at large longitudes; iii) The
massive CMZ with a rectangular field-of-view of shows the maximum of the energy flux per log bin in the
diffuse gamma-ray spectrum at 2 GeV, i.e. the "GeV-excess", already in the raw
data without any analysis. The rectangular profile contradicts the spherical
morphology expected for DM annihilation.Comment: 53 pages, 8 figures (+ 42 figures in Appendices), extended version of
arXiv:1610.08926 accepted for publication in PR
Radiation hardness of diamond and silicon sensors compared
The radiation hardness of silicon charged particle sensors is compared with
single crystal and polycrystalline diamond sensors, both experimentally and
theoretically. It is shown that for Si- and C-sensors, the NIEL hypothesis,
which states that the signal loss is proportional to the Non-Ionizing Energy
Loss, is a good approximation to the present data. At incident proton and
neutron energies well above 0.1 GeV the radiation damage is dominated by the
inelastic cross section, while at non-relativistic energies the elastic cross
section prevails. The smaller inelastic nucleon-Carbon cross section and the
light nuclear fragments imply that at high energies diamond is an order of
magnitude more radiation hard than silicon, while at energies below 0.1 GeV the
difference becomes significantly smaller.Comment: 6 pages, 4 figurs, invited talk at the Hasselt Diamond Workshop, Feb.
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The Role of Normware in Trustworthy and Explainable AI
For being potentially destructive, in practice incomprehensible and for the
most unintelligible, contemporary technology is setting high challenges on our
society. New conception methods are urgently required. Reorganizing ideas and
discussions presented in AI and related fields, this position paper aims to
highlight the importance of normware--that is, computational artifacts
specifying norms--with respect to these issues, and argues for its
irreducibility with respect to software by making explicit its neglected
ecological dimension in the decision-making cycle
periodic Andreev bound states in a Dirac semimetal
Electrons in a Dirac semimetals possess linear dispersion in all three
spatial dimensions, and form part of a developing platform of novel quantum
materials. BiSb supports a three-dimensional Dirac cone at the
Sb-induced band inversion point. Nanoscale phase-sensitive junction technology
is used to induce superconductivity in this Dirac semimetal. Radio frequency
irradiation experiments reveal a significant contribution of 4-periodic
Andreev bound states to the supercurrent in Nb-BiSb-Nb
Josephson junctions. The conditions for a substantial contribution to
the supercurrent are favourable because of the Dirac cone's topological
protection against backscattering, providing very broad transmission
resonances. The large g-factor of the Zeeman effect from a magnetic field
applied in the plane of the junction, allows tuning of the Josephson junctions
from 0 to regimes.Comment: Supplementary information is include
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