1,518 research outputs found

    Game theory framework for MAC parameter optimization in energy-delay constrained sensor networks

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    Optimizing energy consumption and end-to-end (e2e) packet delay in energy-constrained, delay-sensitive wireless sensor networks is a conflicting multiobjective optimization problem. We investigate the problem from a game theory perspective, where the two optimization objectives are considered as game players. The cost model of each player is mapped through a generalized optimization framework onto protocol-specific MAC parameters. From the optimization framework, a game is first defined by the Nash bargaining solution (NBS) to assure energy consumption and e2e delay balancing. Secondy, the Kalai-Smorodinsky bargaining solution (KSBS) is used to find an equal proportion of gain between players. Both methods offer a bargaining solution to the duty-cycle MAC protocol under different axioms. As a result, given the two performance requirements (i.e., the maximum latency tolerated by the application and the initial energy budget of nodes), the proposed framework allows to set tunable system parameters to reach a fair equilibrium point that dually minimizes the system latency and energy consumption. For illustration, this formulation is applied to six state-of-the-art wireless sensor network (WSN) MAC protocols: B-MAC, X-MAC, RI-MAC, SMAC, DMAC, and LMAC. The article shows the effectiveness and scalability of such a framework in optimizing protocol parameters that achieve a fair energy-delay performance trade-off under the application requirements

    РЕТРОСПЕКТИВНЫЙ КЛИНИКО-ЭПИДЕМИОЛОГИЧЕСКИЙ АНАЛИЗ СЛУЧАЕВ ГЕПАТИТА Е В САНКТ-ПЕТЕРБУРГЕ

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    Hepatitis E – zoonotic disease that has received a nosological independence twenty years ago, when Russian scientist, Professor M.S. Balayan, identified the pathogen (hepatitis E). It was believed that the disease can manifest itself only in the acute form, and occur only in regions with subtropical and tropical climate conditions. The development and introduction of practicing of modern scientific research methods for detecting antibodies to activator change, to view the global prevalence of infection and present doubts on inabilities of transformation into a chronic f a retrospective analysis of hospital cases of acute jaundice hepatitis E in Saint-Petersburg.Etiologic accessory to hepatitis E implemented by discovery in serum of patients a specific marker of infection hepatitis E – an anti-HEV.In the analysis of archive documentation for 2000–2011 from the patients which were hospitalized in the Clinical Infectious Diseases Hospital by S.P. Botkin only 11patients were diagnosed with «acute hepatitis E». Which indicates the presence of patients with acute hepatitis E infection among hospitalized in hospitals of the city of St. Petersburg are not endemic for this disease. The presence of cases of disease of the indigenous inhabitants of the city during the past years, which isn’t going beyond its limits, indicates the existence of «autochthonous» hepatitis E.Гепатит Е – зоонозное заболевание, получившее нозологическую самостоятельность двадцать лет назад, когда российским ученым профессором М.С. Балаяном был выявлен возбудитель (вирус гепатита Е). Считалось, что заболевание может протекать только в острой форме и актуально только для регионов с тропическим и субтропическим климатом. Разработка и внедрение в практику научных исследований современных методов детекции антител к возбудителю изменили представление о глобальной распространенности данной инфекции и поставили под сомнение невозможность трансформации в хроническую форму. Целью нашего исследования было проведение ретроспективного анализа госпитальных случаев острого желтушного гепатита Е в г. Санкт-Петербурге. Этиологическая принадлежность к гепатиту Е осуществлялась обнаружением в сыворотке крови больных специфического маркера инфицирования вирусом гепатита Е – анти-ВГЕ. При анализе архивной документации за 2000–2011 гг. больных, госпитализированных в Клиническую инфекционную больницу им. С.П. Боткина с установленным диагнозом «острый гепатит Е», выявлено 11, что свидетельствует о наличии больных острым гепатитом Е среди госпитализированных в инфекционные стационары города Санкт-Петербурга, который не является эндемичным по данному заболеванию. Наличие случаев заболевания у коренных жителей города, на протяжении последних лет не выезжающих за его пределы, свидетельствует о существовании «аутохтонного» гепатита Е

    Modulator-controlled synthesis of microporous STA-26, an interpenetrated 8,3-connected zirconium MOF with the the-i topology, and its reversible lattice shift

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    The authors acknowledge the support of the EPSRC/St Andrews Criticat CDT (RRRP, PAW) and the European Community Seventh Framework Program (FP7/2007-2013) number 608490 (project M4CO2) (KKC, MYM, KIH, PAW). SEA would like to thank the Royal Society and Wolfson Foundation for a merit award. This research made use of the Balena High Performance Computing (HPC) Service at the University of Bath. The research data (and/or materials) supporting this publication can be accessed at DOI: http://dx.doi.org/10.17630/6ffeed8a-e75f-4648-968f-3ed32a94e9a0.A fully interpenetrated 8,3-connected zirconium MOF with the the-i topology type, STA-26 (St Andrews porous material-26), has been prepared using the 4,4',4"-(2,4,6-trimethylbenzene-1,3,5-triyl)tribenzoate (TMTB) tritopic linker with formic acid as a modulating agent. In the as-prepared form STA-26 possesses Im-3m symmetry compared with the Pm-3m symmetry of the non-interpenetrated analogue, NU-1200, prepared using benzoic acid as a modulator. Upon removal of residual solvent there is a shift between the interpenetrating lattices and a resultant symmetry change to Cmcm which is fully reversible. This is observed by X-ray diffraction and 13C MAS NMR is also found to be remarkably sensitive to the structural transition. Furthermore, heating STA-26(Zr) in vacuum dehydroxylates the Zr6 nodes leaving coordinatively unsaturated Zr4+ sites, as shown by IR spectroscopy using CO and CD3CN as probe molecules. Nitrogen adsorption at 77 K together with grand canonical Monte Carlo simulations confirms a microporous, fully interpenetrated, structure with pore volume 0.53 cm3 g−1 while CO2 adsorption at 196 K reaches 300 cm3 STP g−1 at 1 bar. While the pore volume is smaller than that of its non-interpenetrated mesoporous analogue, interpenetration makes the structure more stable to moisture adsorption and introduces shape selectivity in adsorption.PostprintPeer reviewe

    Impact of the Coulomb field on charged-pion spectra in few-GeV heavy-ion collisions

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    In nuclear collisions the incident protons generate a Coulomb field which acts on produced charged particles. The impact of these interactions on charged-pion transverse-mass and rapidity spectra, as well as on pion–pion momentum correlations is investigated in Au + Au collisions at SNN\sqrt{^{S}NN} = 2.4 GeV. We show that the low-mt_{t} region (mt_{t} < 0.2 GeV / c2^{2}) can be well described with a Coulomb-modified Boltzmann distribution that also takes changes of the Coulomb field during the expansion of the fireball into account. The observed centrality dependence of the fitted mean Coulomb potential energy deviates strongly from a Apart2/3A_{part}^{2/3} scaling, indicating that, next to the fireball, the non-interacting charged spectators have to be taken into account. For the most central collisions, the Coulomb modifications of the HBT source radii are found to be consistent with the potential extracted from the single-pion transverse-mass distributions. This finding suggests that the region of homogeneity obtained from two-pion correlations coincides with the region in which the pions freeze-out. Using the inferred mean-square radius of the charge distribution at freeze-out, we have deduced a baryon density, in fair agreement with values obtained from statistical hadronization model fits to the particle yields

    The upgrade of the ALICE TPC with GEMs and continuous readout

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    The upgrade of the ALICE TPC will allow the experiment to cope with the high interaction rates foreseen for the forthcoming Run 3 and Run 4 at the CERN LHC. In this article, we describe the design of new readout chambers and front-end electronics, which are driven by the goals of the experiment. Gas Electron Multiplier (GEM) detectors arranged in stacks containing four GEMs each, and continuous readout electronics based on the SAMPA chip, an ALICE development, are replacing the previous elements. The construction of these new elements, together with their associated quality control procedures, is explained in detail. Finally, the readout chamber and front-end electronics cards replacement, together with the commissioning of the detector prior to installation in the experimental cavern, are presented. After a nine-year period of R&D, construction, and assembly, the upgrade of the TPC was completed in 2020.publishedVersio

    A Joint Fermi-GBM and Swift-BAT Analysis of Gravitational-wave Candidates from the Third Gravitational-wave Observing Run

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    We present Fermi Gamma-ray Burst Monitor (Fermi-GBM) and Swift Burst Alert Telescope (Swift-BAT) searches for gamma-ray/X-ray counterparts to gravitational-wave (GW) candidate events identified during the third observing run of the Advanced LIGO and Advanced Virgo detectors. Using Fermi-GBM onboard triggers and subthreshold gamma-ray burst (GRB) candidates found in the Fermi-GBM ground analyses, the Targeted Search and the Untargeted Search, we investigate whether there are any coincident GRBs associated with the GWs. We also search the Swift-BAT rate data around the GW times to determine whether a GRB counterpart is present. No counterparts are found. Using both the Fermi-GBM Targeted Search and the Swift- BAT search, we calculate flux upper limits and present joint upper limits on the gamma-ray luminosity of each GW. Given these limits, we constrain theoretical models for the emission of gamma rays from binary black hole mergers

    First joint observation by the underground gravitational-wave detector KAGRA with GEO 600

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    We report the results of the first joint observation of the KAGRA detector with GEO 600. KAGRA is a cryogenic and underground gravitational-wave detector consisting of a laser interferometer with 3 km arms, located in Kamioka, Gifu, Japan. GEO 600 is a British-German laser interferometer with 600 m arms, located near Hannover, Germany. GEO 600 and KAGRA performed a joint observing run from April 7 to 20, 2020. We present the results of the joint analysis of the GEO-KAGRA data for transient gravitational-wave signals, including the coalescence of neutron-star binaries and generic unmodeled transients. We also perform dedicated searches for binary coalescence signals and generic transients associated with gamma-ray burst events observed during the joint run. No gravitational-wave events were identified. We evaluate the minimum detectable amplitude for various types of transient signals and the spacetime volume for which the network is sensitive to binary neutron-star coalescences. We also place lower limits on the distances to the gamma-ray bursts analyzed based on the non-detection of an associated gravitational-wave signal for several signal models, including binary coalescences. These analyses demonstrate the feasibility and utility of KAGRA as a member of the global gravitational-wave detector network

    Model-based cross-correlation search for gravitational waves from the low-mass X-ray binary Scorpius X-1 in LIGO O3 data

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    Inclusive e+^+e^- production in collisions of pions with protons and nuclei in the second resonance region of baryons

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    Inclusive e+^+e^- production has been studied with HADES in π\pi^- + p, π\pi^- + C and π+CH2\pi^- + \mathrm{CH}_2 reactions, using the GSI pion beam at sπp\sqrt{s_{\pi p}} = 1.49 GeV. Invariant mass and transverse momentum distributions have been measured and reveal contributions from Dalitz decays of π0\pi^0, η\eta mesons and baryon resonances. The transverse momentum distributions are very sensitive to the underlying kinematics of the various processes. The baryon contribution exhibits a deviation up to a factor seven from the QED reference expected for the dielectron decay of a hypothetical point-like baryon with the production cross section constrained from the inverse γ\gamma nπ\rightarrow \pi^- p reaction. The enhancement is attributed to a strong four-momentum squared dependence of the time-like electromagnetic transition form factors as suggested by Vector Meson Dominance (VMD). Two versions of the VMD, that differ in the photon-baryon coupling, have been applied in simulations and compared to data. VMD1 (or two-component VMD) assumes a coupling via the ρ\rho meson and a direct coupling of the photon, while in VMD2 (or strict VMD) the coupling is only mediated via the ρ\rho meson. The VMD2 model, frequently used in transport calculations for dilepton decays, is found to overestimate the measured dielectron yields, while a good description of the data can be obtained with the VMD1 model assuming no phase difference between the two amplitudes. Similar descriptions have also been obtained using a time-like baryon transition form factor model where the pion cloud plays the major role.Comment: (HADES collaboration
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