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$^\circ$ 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 $l \times b = 3.5^{\circ} \times 0.5^{\circ}$ 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. 200

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

4π4\pi 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. Bi$_{1-x}$Sb$_x$ 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$\pi$-periodic Andreev bound states to the supercurrent in Nb-Bi$_{0.97}$Sb$_{0.03}$-Nb Josephson junctions. The conditions for a substantial $4\pi$ 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 $\pi$ regimes.Comment: Supplementary information is include