88,075 research outputs found

    The hybrid front end PCBs production for the CMS preshower

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    The High Energy Physics Detector CMS (Compact Muon Solenoid),installed at the Large Hadron Collider(LHC) at CERN,Geneva,has been built by an International Collaboration;CMS will measure and identify the particles from proton-proton collisions.One of the CMS component is the Preshower sub-detector,comprising 5000 silicon strip sensors connected to Hybrid Front End Boards for the readout.This paper focuses on an in-kind contibution of Greece.This work was carried out by researches,engineers and managers from a medium size Company,Prisma Electronics,located in Alexandropolis and researchers from CERN in Geneva,Demokritos in Athens and the University of Ioannina.The number of pieces fitting the technical specifications was close to 100%.Because of that,in March 2009,Prisma received as recognition a CERN CMS gold award

    Strong dust processing in circumstellar discs around 6 RV Tauri stars. Are dusty RV Tauri stars all binaries?

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    We present extended Spectral Energy Distributions (SEDs) of seven classical RV Tauri stars, using newly obtained submillimetre continuum measurements and Geneva optical photometry supplemented with literature data. The broad-band SEDs show a large IR excess with a black-body slope at long wavelengths in six of the seven stars, R Sct being the noticeable exception. This long wavelength slope is best explained assuming the presence of a dust component of large grains in the circumstellar material. We show that the most likely distribution of the circumstellar dust around the six systems is that the dust resides in a disc. Moreover, very small outflow velocities are needed to explain the presence of dust near the sublimation temperature and we speculate that the discs are Keplerian. The structure and evolution of these compact discs are as yet not understood but a likely prerequisite for their formation is that the dusty RV Tauri stars are binaries.Comment: 10 pages, will be published in A&

    Specifying ODP computational objects in Z

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    The computational viewpoint contained within the Reference Model of Open Distributed Processing (RM-ODP) shows how collections of objects can be configured within a distributed system to enable interworking. It prescribes certain capabilities that such objects are expected to possess and structuring rules that apply to how these objects can be configured with one another. This paper highlights how the specification language Z can be used to formalise these capabilities and the associated structuring rules, thereby enabling specifications of ODP systems from the computational viewpoint to be achieved

    Implications of the metallicity dependence of Wolf-Rayet winds

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    Aims: Recent theoretical predictions for the winds of Wolf-Rayet stars indicate that their mass-loss rates scale with the initial stellar metallicity in the local Universe.We aim to investigate how this predicted dependence affects the models of Wolf-Rayet stars and their progeny in different chemical environments. Methods: We compute models of stellar structure and evolution for Wolf-Rayet stars for different initial metallicities, and investigate how the scaling of the Wolf-Rayet mass-loss rates affects the final masses, the lifetimes of the WN and WC subtypes, and how the ratio of the two populations vary with metallicity. Results: We find significant effects of metallicity dependent mass-loss rates for Wolf-Rayet stars. For models that include the scaling of the mass-loss rate with initial metallicity, all WR stars become neutron stars rather than black holes at twice the solar metallicity; at lower ZZ, black holes have larger masses. We also show that our models that include the mass-loss metallicity scaling closely reproduce the observed decrease of the relative population of WC over WN stars at low metallicities.Comment: 8 pages, 9 figures, accepted by Astronomy & Astrophysic

    A universe of processes and some of its guises

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    Our starting point is a particular `canvas' aimed to `draw' theories of physics, which has symmetric monoidal categories as its mathematical backbone. In this paper we consider the conceptual foundations for this canvas, and how these can then be converted into mathematical structure. With very little structural effort (i.e. in very abstract terms) and in a very short time span the categorical quantum mechanics (CQM) research program has reproduced a surprisingly large fragment of quantum theory. It also provides new insights both in quantum foundations and in quantum information, and has even resulted in automated reasoning software called `quantomatic' which exploits the deductive power of CQM. In this paper we complement the available material by not requiring prior knowledge of category theory, and by pointing at connections to previous and current developments in the foundations of physics. This research program is also in close synergy with developments elsewhere, for example in representation theory, quantum algebra, knot theory, topological quantum field theory and several other areas.Comment: Invited chapter in: "Deep Beauty: Understanding the Quantum World through Mathematical Innovation", H. Halvorson, ed., Cambridge University Press, forthcoming. (as usual, many pictures

    Book Review: The Rights International Companion to Criminal Law & Procedure: An International Human Rights & Humanitarian Law Supplement

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    This Book Review provides a compact supplement to teaching criminal law and procedure by providing materials on the sources and application of international human rights and humanitarian law to criminal law. Part One reviews the sources and principles of international law. Part Two contains treaties and statutes setting forth the principles of state liability and individual culpability. Part Three provides excerpts from some of the major international criminal tribunals and some of the applicable treaty law. Part Four discusses criminal procedure. Part Five contains a discussion of principles of punishment for international crimes and the consideration of the death penalty in punishment. This Book is a valuable contribution to new and dynamic aspects of the interplay between international human rights and international criminal la

    Massive star population synthesis with binaries

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    We first give a short historical overview with some key facts of massive star population synthesis with binaries. We then discuss binary population codes and focus on two ingredients which are important for massive star population synthesis and which may be different in different codes. Population simulations with binaries is the third part where we consider the initial massive binary frequency, the RSG/WR and WC/WN and SNII/SNIbc number ratio's, the probable initial rotational velocity distribution of massive stars.Comment: 5 pages, 1 figure, review paper to appear in the conference proceedings of the June 2015 Potsdam Wolf-Rayet workshop, edited by W.-R. Hamann, A. Sander, and H. Tod
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