Centaurus A at Hard X-rays and Soft Gamma-rays

Centaurus A, at a distance of less than 4 Mpc, is the nearest radio-loud AGN. Its emission is detected from radio to very-high energy gamma-rays. Despite the fact that Cen A is one of the best studied extragalactic objects the origin of its hard X-ray and soft gamma-ray emission (100 keV < E < 50 MeV) is still uncertain. Observations with high spatial resolution in the adjacent soft X-ray and hard gamma-ray regimes suggest that several distinct components such as a Seyfert-like nucleus, relativistic jets, and even luminous X-ray binaries within Cen A may contribute to the total emission in the MeV regime that has been detected with low spatial resolution. As the Spectral Energy Distribution of Cen A has its second maximum around 1 MeV, this energy range plays an important role in modeling the emission of (this) AGN. As there will be no satellite mission in the near future that will cover this energies with higher spatial resolution and better sensitivity, an overview of all existing hard X-ray and soft gamma-ray measurements of Cen A is presented here defining the present knowledge on Centaurus A in the MeV energy range.Comment: 8 pages, 5 figures, article for conference proceedings "The Many Faces of Centaurus A"; accepted for publication in PAS

Properties of an ionization spectrometer exposed to 10, 20.5, and 28 GeV/c machine accelerated protons

Properties of ionization spectrometer exposed to 10, 20.5, and 28 GeV/c synchrotron accelerated proton

„Wissensraum Architektur“– A Constructivist Model of Learning for Architectural Education at Anhalt University of Applied Sciences

The study of architecture is by nature highly interdisciplinary. Design, structure, technology, ecology and economics must all be considered in the process of planning and building. Therefore it is important to encourage an integrated approach in terms of education and to create a interdisciplinary network of learning contents. Wissensraum Architektur is a contribution to this idea. Wissensraum Architektur is an internet-based system for teaching and learning at the Department of Architecture and Civil Engineering at Anhalt University of Applied Sciences in Dessau. The basis of Wissensraum is a pool of media elements and multimedia based components to which authors from different fields contribute. The authoring system allows instructors to create, by simple means, digital learning modules. Due to the modular structure, modular elements and sequences in varying relations and by different authors can be reused and restructured. A knowledge map visualizes relationships among the different learning content. In this way, a virtual campus in Dessau is created step by step. The didactical concept of Wissensraum supports Constructivist models of learning. Users can use the database for research and can create their own way of learning concerning particular themes. The availability via Internet makes it possible to work from any location at any time

Neutrino, Neutron, and Cosmic Ray Production in the External Shock Model of Gamma Ray Bursts

The hypothesis that ultra-high energy (>~ 10^19 eV) cosmic rays (UHECRs) are accelerated by gamma-ray burst (GRB) blast waves is assumed to be correct. Implications of this assumption are then derived for the external shock model of gamma-ray bursts. The evolving synchrotron radiation spectrum in GRB blast waves provides target photons for the photomeson production of neutrinos and neutrons. Decay characteristics and radiative efficiencies of the neutral particles that escape from the blast wave are calculated. The diffuse high-energy GRB neutrino background and the distribution of high-energy GRB neutrino events are calculated for specific parameter sets, and a scaling relation for the photomeson production efficiency in surroundings with different densities is derived. GRBs provide an intense flux of high-energy neutrons, with neutron-production efficiencies exceeding ~ 1% of the total energy release. The radiative characteristics of the neutron beta-decay electrons from the GRB "neutron bomb" are solved in a special case. Galaxies with GRB activity should be surrounded by radiation halos of ~ 100 kpc extent from the outflowing neutrons, consisting of a nonthermal optical/X-ray synchrotron component and a high-energy gamma-ray component from Compton-scattered microwave background radiation. The luminosity of sources of GRBs and relativistic outflows in L* galaxies such as the Milky Way is at the level of ~10^40+-1 ergs/s. This is sufficient to account for UHECR generation by GRBs. We briefly speculate on the possibility that hadronic cosmic rays originate from the subset of supernovae that collapse to form relativistic outflows and GRBs. (abridged)Comment: 53 pages, 8 figures, ApJ, in press, 574, July 20, 2002. Substantial revision, previous Appendix expanded to ApJ, 556, 479; cosmic ray origin speculations to Heidelberg (astro-ph/001054) and Hamburg ICRC (astro-ph/0202254) proceeding

FGF23-klotho axis as predictive factors of fractures in type 2 diabetics with early chronic kidney disease

Background: The aim of our study was to evaluate the relevance of FGF23-klotho axis in the predisposition for bone fractures in type 2 diabetic patients with early chronic kidney disease. Methods: In a prospective study we included 126 type 2 diabetic patients with CKD stages 2-3 (from 2010 to 2017). We used descriptive statistics, ANOVA and chi-square test. Our population was divided into two groups according to the occurrence of a bone fracture event or not, and the groups were compared considering several biological and laboratorial parameters. We employed a multiple regression model to identify risk factors for bone fracture events and hazard ratios (HR) were calculated using a backward stepwise likelihood ratio (LR) Cox regression. Results: Patients with a fracture event displayed higher levels of FGF-23, Phosphorus, PTH, TNF-alpha, OxLDL, HOMA-IR, calcium x phosphorus product and ACR and lower levels of Osteocalcin, alpha-Klotho, 25(OH)D3 and eGFR compared with patients without a fracture event (p < 0.001). The number of patients with a fracture event was higher than expected within inclining CKD stages (chi 2, p = 0.06). The occurrence of fracture and the levels of TNF-alpha, klotho, 25(OH)D3 and OxLDL were found to predict patient entry into RRT (p < 0.05). Age, osteocalcin, alpha-Klotho and FGF-23 independently influenced the occurrence of bone fracture (p < 0.05). Conclusions: alpha-Klotho and FGF-23 levels may have a good clinical use as biomarkers to predict the occurrence of fracture events. (C) 2019 Elsevier Inc. All rights reserved.info:eu-repo/semantics/publishedVersio

Energy Linearity and Resolution of the ATLAS Electromagnetic Barrel Calorimeter in an Electron Test-Beam

A module of the ATLAS electromagnetic barrel liquid argon calorimeter was exposed to the CERN electron test-beam at the H8 beam line upgraded for precision momentum measurement. The available energies of the electron beam ranged from 10 to 245 GeV. The electron beam impinged at one point corresponding to a pseudo-rapidity of eta=0.687 and an azimuthal angle of phi=0.28 in the ATLAS coordinate system. A detailed study of several effects biasing the electron energy measurement allowed an energy reconstruction procedure to be developed that ensures a good linearity and a good resolution. Use is made of detailed Monte Carlo simulations based on Geant which describe the longitudinal and transverse shower profiles as well as the energy distributions. For electron energies between 15 GeV and 180 GeV the deviation of the measured incident electron energy over the beam energy is within 0.1%. The systematic uncertainty of the measurement is about 0.1% at low energies and negligible at high energies. The energy resolution is found to be about 10% sqrt(E) for the sampling term and about 0.2% for the local constant term