609 research outputs found

    The effect of Coulomb interaction at ferromagnetic-paramagnetic metallic perovskite junctions

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    We study the effect of Coulomb interactions in transition metal oxides junctions. In this paper we analyze charge transfer at the interface of a three layer ferromagnetic-paramagnetic-ferromagnetic metallic oxide system. We choose a charge model considering a few atomic planes within each layer and obtain results for the magnetic coupling between the ferromagnetic layers. For large number of planes in the paramagnetic spacer we find that the coupling oscillates with the same period as in RKKY but the amplitude is sensitive to the Coulomb energy. At small spacer thickness however, large differences may appear as function of : the number of electrons per atom in the ferromagnetics and paramagnetics materials, the dielectric constant at each component, and the charge defects at the interface plane emphasizing the effects of charge transfer.Comment: tex file and 7 figure

    European consensus on grading bone marrow fibrosis and assessment of cellularity

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    Quantification of characteristic bone marrow biopsy features includes basic parameters such as cellularity and fiber content. These are important to assess the dynamics of disease processes with a significant impact on risk stratification, survival patterns and, especially, therapy-related changes. A panel of experienced European pathologists and a foreign expert evaluated, at a multi-headed microscope, a large number of representative slides of trephine biopsies from patients with myelofibrosis in an attempt to reach a consensus on how to grade cellularity and fibrosis. This included a critical evaluation of previously described scoring systems. During the microscopic analysis and subsequent discussion and voting, the importance of age-dependent decrease in cellularity was recognized. Grading of myelofibrosis was simplified by using four easily reproducible categories including differentiation between reticulin and collagen. A consensus was reached that the density of fibers must be assessed in relation to the hematopoietic tissue. This feature is especially important in order to avoid a false impression of a reduced fiber content in fatty and/or edematous bone marrow samples after treatment. The consensus for measuring myelofibrosis by clear and reproducible guidelines achieved by our group should allow for precise grading during the disease process and after therapy

    Electronic structure, magnetism, and disorder in the Heusler compound Co2_2TiSn

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    Polycrystalline samples of the half-metallic ferromagnet Heusler compound Co2_2TiSn have been prepared and studied using bulk techniques (X-ray diffraction and magnetization) as well as local probes (119^{119}Sn M\"ossbauer spectroscopy and 59^{59}Co nuclear magnetic resonance spectroscopy) in order to determine how disorder affects half-metallic behavior and also, to establish the joint use of M\"ossbauer and NMR spectroscopies as a quantitative probe of local ion ordering in these compounds. Additionally, density functional electronic structure calculations on ordered and partially disordered Co2_2TiSn compounds have been carried out at a number of different levels of theory in order to simultaneously understand how the particular choice of DFT scheme as well as disorder affect the computed magnetization. Our studies suggest that a sample which seems well-ordered by X-ray diffraction and magnetization measurements can possess up to 10% of antisite (Co/Ti) disordering. Computations similarly suggest that even 12.5% antisite Co/Ti disorder does not destroy the half-metallic character of this material. However, the use of an appropriate level of non-local DFT is crucial.Comment: 11 pages and 5 figure

    One Last Puff? - Public Smoking Bans and Smoking Behavior

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    This paper investigates the short-term effects of public smoking bans on individual smoking behavior. In 2007 and 2008, state-level smoking bans were gradually introduced in all of Germany's sixteen federal states. We exploit this variation in the timing of state bans to identify the effect that smoke-free policies had on individuals' smoking propensity and smoking intensity. Using rich longitudinal data from the German Socio-Economic Panel Study, our difference-in-differences estimates show that the introduction of smoke-free legislation in Germany did not change average smoking behavior within the population. However, our estimates also point to important heterogeneous effects. Groups that go out more often, and hence are more exposed to the constraints of public smoking bans in everyday life, did adjust their smoking behavior. Specifically, we find that young, unmarried individuals, and those living in urban areas are groups that are both less likely to smoke and smoke less intensively following the introduction of public smoking bans. Furthermore, effects on individual smoking habits proved stronger in states that had more strict smoking bans. Public smoking bans, therefore, have important health benefits over and above the reduction in exposure of non-smokers to second-hand smoke that is their immediate and prime objective.Das vorliegende Papier untersucht anhand von Daten des Sozio-Oekonomischen Panels (SOEP) die kurzfristige Wirkung von öffentlichen Rauchverboten auf das Rauchverhalten in Deutschland. In den Jahren 2007 und 2008 wurden sukzessive Rauchverbote in allen sechzehn Bundesländern eingeführt. Diese zeitliche Variation erlaubt die Messung der Auswirkung von Rauchverboten auf die Wahrscheinlichkeit von Individuen zu rauchen sowie auf die Höhe ihres Zigarettenkonsums. Die Ergebnisse unserer Differenzen-in-Differenzen Schätzungen zeigen, dass die Verbote das durchschnittliche Rauchverhalten in der Bevölkerung insgesamt nicht beeinflussten. Doch finden wir relevante Effekte für Personengruppen, die traditionell häufiger ausgehen (jüngere Jahrgänge, unverheiratete Personen und Einwohner größerer Städte). Diese sind durch ihr häufigeres Ausgehverhalten den Beschränkungen von Rauchverboten im Alltag stärker ausgesetzt und weisen in Folge der Verbote niedrigere Wahrscheinlichkeiten auf, zu rauchen. Ferner finden sich Hinweise, dass sich striktere Rauchverbote stärker auf das Rauchverhalten auswirkten. Rauchverbote haben somit, neben ihrem eigentlichen Ziel, das Ausmaß des Passivrauchens im öffentlichen Raum zu reduzieren, eine wichtige und zusätzliche gesundheitsfördernde Wirkung

    Shower development of particles with momenta from 15 GeV to 150 GeV in the CALICE scintillator-tungsten hadronic calorimeter

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    We present a study of showers initiated by electrons, pions, kaons, and protons with momenta from 15 GeV to 150 GeV in the highly granular CALICE scintillator-tungsten analogue hadronic calorimeter. The data were recorded at the CERN Super Proton Synchrotron in 2011. The analysis includes measurements of the calorimeter response to each particle type as well as measurements of the energy resolution and studies of the longitudinal and radial shower development for selected particles. The results are compared to Geant4 simulations (version 9.6.p02). In the study of the energy resolution we include previously published data with beam momenta from 1 GeV to 10 GeV recorded at the CERN Proton Synchrotron in 2010.Comment: 35 pages, 21 figures, 8 table

    Infrastructure for Detector Research and Development towards the International Linear Collider

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    The EUDET-project was launched to create an infrastructure for developing and testing new and advanced detector technologies to be used at a future linear collider. The aim was to make possible experimentation and analysis of data for institutes, which otherwise could not be realized due to lack of resources. The infrastructure comprised an analysis and software network, and instrumentation infrastructures for tracking detectors as well as for calorimetry.Comment: 54 pages, 48 picture

    Public Smoking Bans, Youth Access Laws, and Cigarette Sales at Vending Machines

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    Tobacco control policies have proliferated in many countries in recent years, in particular youth access laws and public smoking bans. The effectiveness of youth access laws is still disputed, however, as are the costs of public smoking bans to the hospitality industry. Using a unique data set on cigarette sales at more than 100k vending machines that provides first objective evidence on the outgoing and customer behavior of smokers, we study both outcome dimensions by investigating several recent tobacco control measures in Germany. We find a large negative effect on cigarette sales of a nation-wide introduction of devices for electronic age verification in cigarette vending machines, particularly at machines placed outdoors and in localities that are strongly frequented by youths. In contrast, there is no evidence that a country-wide smoking ban in federal buildings affected cigarette sales in these premises and only weak evidence that a recent rise in the minimum legal smoking age affected cigarette purchases by youths. Finally, state-level smoking bans appear to have reduced indoor sales of cigarettes at vending machines, especially in bars. However, the magnitude of the estimated effect is rather modest, suggesting that businesses in the hospitality industry are unlikely to have been affected severely.Das vorliegende Papier untersucht anhand von Umsatzdaten an Zigarettenautomaten die Wirkungen von vier verschiedenen Maßnahmen zur Kontrolle bzw. Begrenzung des Zigarettenkonsums in Deutschland: die elektronische Alterskennung an Automaten (Januar 2007), die Anhebung des Mindestalters für den Erwerb und Konsum von Zigaretten von 16 auf 18 Jahren (September 2007), das Rauchverbot in Einrichtungen des Bundes (ebenfalls September 2007) sowie Rauchverbote in der Gastronomie auf Länderebene (zwischen August 2007 und Juli 2008). Die Ergebnisse zeigen einen starken Rückgang des Zigarettenabsatzes an Automaten in Folge der Einführung der elektronischen Alterskennung, besonders an Automaten im Außenbereich und in Einrichtungen, die stark von Jugendlichen frequentiert werden. Im Gegensatz findet sich jedoch keine Evidenz dafür, dass das Rauchverbot in Einrichtungen des Bundes zu einem Rückgang des Absatzes an Zigarettenautomaten in diesen Einrichtungen geführt hat. Auch gibt es nur schwache Evidenz für einen Einfluss der Anhebung des Mindestalters auf den Erwerb von Zigaretten durch Jugendliche. Rauchverbote auf Bundeslandebene hingegen haben den Zigarettenabsatz an Automaten im Innenbereich reduziert, besonders in Kneipen. Die moderate Größe dieses Effektes legt jedoch den Schluss nahe, dass Gastronomiebetriebe durch die Rauchverbote keine starken Umsatzeinbußen erfuhren

    Performance studies of the Belle II Silicon Vertex Detector with data taken at the DESY test beam in April 2016

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    Belle II is a multipurpose detector currently under construction which will be operated at the next generation B-factory SuberKEKB in Japan. Its main devices for the vertex reconstruction are the Silicon Vertex Detector (SVD) and the Pixel Detector (PXD). In April 2016 a sector of the Belle II SVD and PXD have been tested in a beam of high energetic electrons at the test beam facility at DESY Hamburg (Germany). We report here the results for the hit efficiency estimation and the measurement of the resolution for the Belle II silicon vertex etector. We find that the hit efficiencies are on average above 99.5% and that the measured resolution is within the expectations

    Performance studies of the Belle II Silicon Vertex Detector with data taken at the DESY test beam in April 2016

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    Belle II is a multipurpose detector currently under construction which will be operated at the next generation B-factory SuberKEKB in Japan. Its main devices for the vertex reconstruction are the Silicon Vertex Detector (SVD) and the Pixel Detector (PXD). In April 2016 a sector of the Belle II SVD and PXD have been tested in a beam of high energetic electrons at the test beam facility at DESY Hamburg (Germany). We report here the results for the hit efficiency estimation and the measurement of the resolution for the Belle II silicon vertex etector. We find that the hit efficiencies are on average above 99.5% and that the measured resolution is within the expectations

    The Belle II SVD detector

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    The Silicon Vertex Detector (SVD) is one of the main detectors in the Belle II experiment at KEK, Japan. In combination with a pixel detector, the SVD determines precise decay vertex and low-momentum track reconstruction. The SVD ladders are being developed at several institutes. For the development of the tracking algorithm as well as the performance estimation of the ladders, beam tests for the ladders were performed. We report an overview of the SVD development, its performance measured in the beam test, and the prospect of its assembly and commissioning until installation
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