The High Energy Emission of the Crab Nebula from 20 keV to 6 MeV with INTEGRAL

The SPI spectrometer aboard the INTEGRAL mission observes regularly the Crab Nebula since 2003. We report on observations distributed over 5.5 years and investigate the variability of the intensity and spectral shape of this remarkable source in the hard X-rays domain up to a few MeV. While single power law models give a good description in the X-ray domain (mean photon index ~ 2.05) and MeV domain (photon index ~ 2.23), crucial information are contained in the evolution of the slope with energy between these two values. This study has been carried out trough individual observations and long duration (~ 400 ks) averaged spectra. The stability of the emission is remarkable and excludes a single power law model. The slopes measured below and above 100 keV agree perfectly with the last values reported in the X-ray and MeV regions respectively, but without indication of a localized break point. This suggests a gradual softening in the emission around 100 keV and thus a continuous evolution rather than an actual change in the mechanism parameters. In the MeV region, no significant deviation from the proposed power law model is visible up to 5-6 MeV. Finally, we take advantage of the spectroscopic capability of the instrument to seek for previously reported spectral features in the covered energy range with negative results for any significant cyclotron or annihilation emission on 400 ks timescales. Beyond the scientific results, the performance and reliability of the SPI instrument is explicitly demonstrated, with some details about the most appropriate analysis method.Comment: accepted for publication in ApJ; 4 figures, 2 table

GRI: The Gamma-Ray Imager mission

With the INTEGRAL observatory, ESA has provided a unique tool to the astronomical community revealing hundreds of sources, new classes of objects, extraordinary views of antimatter annihilation in our Galaxy, and fingerprints of recent nucleosynthesis processes. While INTEGRAL provides the global overview over the soft gamma-ray sky, there is a growing need to perform deeper, more focused investigations of gamma-ray sources. In soft X-rays a comparable step was taken going from the Einstein and the EXOSAT satellites to the Chandra and XMM/Newton observatories. Technological advances in the past years in the domain of gamma-ray focusing using Laue diffraction have paved the way towards a new gamma-ray mission, providing major improvements regarding sensitivity and angular resolution. Such a future Gamma-Ray Imager will allow studies of particle acceleration processes and explosion physics in unprecedented detail, providing essential clues on the innermost nature of the most violent and most energetic processes in the Universe.Comment: 8 page

White paper on crowdsourced network and QoE measurements – definitions, use cases and challenges

The goal of the white paper at hand is as follows. The definitions of the terms build a framework for discussions around the hype topic ‘crowdsourcing’. This serves as a basis for differentiation and a consistent view from different perspectives on crowdsourced network measurements, with the goal to provide a commonly accepted definition in the community. The focus is on the context of mobile and fixed network operators, but also on measurements of different layers (network, application, user layer). In addition, the white paper shows the value of crowdsourcing for selected use cases, e.g., to improve QoE or regulatory issues. Finally, the major challenges and issues for researchers and practitioners are highlighted. This white paper is the outcome of the Würzburg seminar on “Crowdsourced Network and QoE Measurements” which took place from 25-26 September 2019 in Würzburg, Germany. International experts were invited from industry and academia. They are well known in their communities, having different backgrounds in crowdsourcing, mobile networks, network measurements, network performance, Quality of Service (QoS), and Quality of Experience (QoE). The discussions in the seminar focused on how crowdsourcing will support vendors, operators, and regulators to determine the Quality of Experience in new 5G networks that enable various new applications and network architectures. As a result of the discussions, the need for a white paper manifested, with the goal of providing a scientific discussion of the terms “crowdsourced network measurements” and “crowdsourced QoE measurements”, describing relevant use cases for such crowdsourced data, and its underlying challenges. During the seminar, those main topics were identified, intensively discussed in break-out groups, and brought back into the plenum several times. The outcome of the seminar is this white paper at hand which is – to our knowledge – the first one covering the topic of crowdsourced network and QoE measurements

SONTRAC—A low background, large area solar neutron spectrometer

SONTRAC is a scintillating fiber neutron detector designed to measure solar flare neutrons from a balloon or spacecraft platform. The instrument is comprised of alternating orthogonal planes of scintillator fibers viewed by photomultiplier tubes and image intensifier/CCD camera optics. It operates by tracking the paths of recoil protons from the double scatter of 20 to 200 MeV neutrons off hydrogen in the plastic scintillator, thereby providing the necessary information to determine the incident neutron direction and energy. SONTRAC is also capable of detecting and measuring high-energy gamma rays \u3e20 MeV as a “solid-state spark chamber.” The self-triggering and track imaging features of a prototype for tracking in two dimensions have been demonstrated in calibrations with cosmic-ray muons, 14 to ∼65 MeV neutrons and ∼20 MeV protons

Functional Morphology of the Divided Compound Eye of the Honeybee Drone (Apis mellifera)

Using different approaches, the functional morphology of the compound eye of the honeybee drone was examined. The drone exhibits an extended acute zone in the dorsal part of its eye. The following specializations were found here: enlarged facet diameters; smaller interommatidial angles; red-leaky screening pigment; enlarged rhabdom diameters; photopigment composition different from the drone’s ventral eye region and the worker bee’s eye. Thus, similar to other male insects, the drone compound eye is divided into a male-specific dorsal part and a ventral part resembling the worker bee’s eye. The functional significance of the sex-specific acute zone is discussed with respect to mating behaviour

Revisiting the Expected Cost of Solving uSVP and Applications to LWE

Abstract: Reducing the Learning with Errors problem (LWE) to the Unique-SVP problem and then applying lattice reduction is a commonly relied-upon strategy for estimating the cost of solving LWE-based constructions. In the literature, two different conditions are formulated under which this strategy is successful. One, widely used, going back to Gama & Nguyen\u27s work on predicting lattice reduction (Eurocrypt 2008) and the other recently outlined by Alkim et al. (USENIX 2016). Since these two estimates predict significantly different costs for solving LWE parameter sets from the literature, we revisit the Unique-SVP strategy. We present empirical evidence from lattice-reduction experiments exhibiting a behaviour in line with the latter estimate. However, we also observe that in some situations lattice-reduction behaves somewhat better than expected from Alkim et al.\u27s work and explain this behaviour under standard assumptions. Finally, we show that the security estimates of some LWE-based constructions from the literature need to be revised and give refined expected solving costs

Anna Korda in einem Film von Daniel Andrew Wunderer

Diese Diplomarbeit, welche aus einem schriftlichem und einem filmischen Teil besteht, versucht drei Dinge: Erstens eine adäquate filmische Biographie von Anna Korda zu bieten. Um dies zu bewerkstelligen, fragt sie zweitens, welche filmischen Mittel dem Historiker und Filmmacher zur Verfügung stehen, um Authentizität zu schaffen bzw. diese zu dekonstruieren, um den Zuschauer entweder in alternative Realitäten zu führen oder aus ihnen hinaus zu stoßen. Von diesen Mittel gilt drittens ein besonderes Augenmerk der Drei-Akt-Struktur, welche theoretisiert und dann auf ihre Anwendbarkeit beim Dokumentarfilm geprüft wird. 1. Anna Korda lebt heute wieder in Wien. 1939 musste die Halbjüdin aus der Stadt flüchten. In England wurde sie Theaterschauspielerin. Dann geht sie mit ihrem Mann nach Rom, um Filmschauspielerin zu werden. Die Filmstadt erlebt gerade ihre Blütezeit. Als Schauspielerin kann Anna sich jedoch nicht etablieren, daher wird sie Sprachtrainerin für italienische, spanische und französische Darsteller. In dieser Funktion arbeitet sie an Filmen mit Mastroianni, Brando und Connery und für Regisseure wie Sergio Leone, Dario Argento, Terrence Young, Fred Zinnemann und vielen mehr. Ab den 80ern gehen die Aufträge stetig zurück. Langsam stirbt das italienische Filmgeschäft. Als sie es sich nicht mehr leisten kann, in Rom zu leben, kehr sie nach Wien zurück, dort lebt sie in einer kleinen Wohnung. Sie geht gern ins Kino und schwelgt in Erinnerung an eine vergangene Zeit. 2. Der Film verfügt über unzählige Mittel um Authentizität zu schaffen, dieselben Mittel können aber auch verwendet werden, um diese zu zerstören oder dem Zuseher mehr Quellentransparenz zu bieten. Dazu gehören unter anderem Text, Audiokommentar, Farbgebung und Musik. 3. Diese Arbeit versucht zu belegen, dass der Dokumentarfilm vor sich vor allem formal und nicht durch Wirklichkeitsnähe vom Spielfilm unterscheidet. Er verwendet Selektion nicht freies Erfinden als realitätsbildendes Mittel. Daher kann er ohne weiteres auf Strukturen zurückgreifen, die dem Spielfilm vorbehalten scheinen. Es wird festgestellt, dass die Drei-Akt-Struktur beim Dokumentarfilm bereits zur Anwendung kommt und auch funktionieren kann. Sie stellt jedoch nicht notgedrungen die beste Variante dar, einen Film zu gestalten. Diese hängt vielmehr vom Stoff, vom Filmemacher und davon ab, wie er an die Geschichte herangehen will. Die Filmindustrie sollte ihre (notwendigen) Produktionsroutinen, zu denen auch Filmstruktur zählt, flexibel halten und nicht ein Paradigma als das einzig mögliche annehmen. [Die Printausgabe enthält 1 DVD