7,965 research outputs found

    Additional spectroscopic redshift measurements for galaxy clusters from the First Planck Catalogue

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    We present the results of spectroscopic redshift measurements for the galaxy clusters from the first all-sky Planck catalogue of the Sunyaev-Zeldovich sources, that have been mostly identified by means of the optical observations performed previously by our team (Planck Collaboration, 2015a). The data on 13 galaxy clusters at redshifts from z=~0.2 to z=~0.8, including the improved identification and redshift measurement for the cluster PSZ1 G141.73+14.22 at z=0.828, are provided. The measurements were done using the data from Russian-Turkish 1.5-m telescope (RTT-150), 2.2-m Calar Alto Observatory telescope, and 6-m SAO RAS telescope (Bolshoy Teleskop Azimutalnyi, BTA).Comment: published in Astronomy Letter

    Gibbs attractor: a chaotic nearly Hamiltonian system, driven by external harmonic force

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    A chaotic autonomous Hamiltonian systems, perturbed by small damping and small external force, harmonically dependent on time, can acquire a strange attractor with properties similar to that of the canonical distribution - the Gibbs attractor. The evolution of the energy in such systems can be described as the energy diffusion. For the nonlinear Pullen - Edmonds oscillator with two degrees of freedom the properties of the Gibbs attractor and their dependence on parameters of the perturbation are studied both analytically and numerically.Comment: 8 pages RevTeX, 3 figure

    ROLE OF THE CELLULAR IMMUNITY IN THE PATHOGENESIS OF BRAIN CONTUSION

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    Traumatic brain injury (TBI) is one of the most common pathologies of the central nervous system in the world, and the use of structural neuroimaging methods – computed tomography (CT) and magnetic resonance imaging (MRI) – often doesn’t allow assessment of the severity of the brain injury that has occurred. This situation predetermines the need to search for new methods of differential diagnosis of the severity of TBI and predicting the risk of consequences.One of these promising areas is the study of the immune status, since traumatic brain injury is characterized by a high rate of complications.One of these promising areas is the study of the immune status in patients with TBI in the acute period. It is now known that in response to brain damage, a response from the immune system is triggered.The reactions from the immune system, which develop after brain injury and directed against its own antigens, in the early period of the disease are related to damage to the nervous tissue. However, according to the latest available data, they are subsequently able to stimulate the processes of repair and regeneration in the brain tissue. In the course of damage to the nervous tissue, in response to endogenous molecules formed during the destruction of cells and the extracellular matrix, the cells of the immune system are activated.Current evidence indicates that T-cells play a role in both the formation of secondary damage and repair mechanisms. They are able to protect neurons through the production of neurotrophic factors such as brain neurotrophic factor (BDNF), which stimulates the growth of neurons, the formation of synapses.Using multicolor cytometric analysis within the framework of this work, a study was carried out to determine the number of the main subpopulations of CD3+CD4+-lymphocytes. The relative number of Th17 (CXCR5- CXCR3- CCR6+CCR4- ) and Th17/Th22 (CXCR5- CXCR3- CCR6+CCR4+), Th1/Th17 (CXCR5- CXCR3+CCR6+CCR4- ) among total CD45RA-negative CD3+CD4+-cells population is significantly increased in comparison with the values in the control group, in turn, the Th1(CXCR5- CXCR3+CCR6- CCR4- ) subpopulations among total CD45RA-negative CD3+CD4+-cells are significantly decreased with the values in the control group. The results obtained so far make it possible to consider immune responses among the key links in the pathogenesis of brain contusion TBI. And, perhaps, a comprehensive immunological examination of the victims in the first day after the injury will determine the parameters that will help predict the nature of possible complications in patients with brain contusion

    An artificial dielectric slab for ultra high-field MRI: proof of concept

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    High-permittivity dielectric pads, i.e., thin, flexible slabs, usually consisting of mixed ceramic powders and liquids, have been previously shown to increase the magnetic field at high and ultra high-fields in regions of low efficiency of transmit coils, thus improving the homogeneity of images. However, their material parameters can change with time, and some materials they contain are bio incompatible. This article presents an alternative approach replacing ceramic mixtures with a low-cost and stable artificial dielectric slab. The latter comprises a stack of capacitive grids realized using multiple printed-circuit boards. Results in this article show that the proposed artificial dielectric structure can obtain the same increase in the local transmit radiofrequency magnetic field distribution in a head phantom at 7 T as the conventional dielectric pad. (C) 2020 The Authors. Published by Elsevier Inc.Radiolog

    A novel application of Fiber Bragg Grating (FBG) sensors in MPGD

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    We present a novel application of Fiber Bragg Grating (FBG) sensors in the construction and characterisation of Micro Pattern Gaseous Detector (MPGD), with particular attention to the realisation of the largest triple (Gas electron Multiplier) GEM chambers so far operated, the GE1/1 chambers of the CMS experiment at LHC. The GE1/1 CMS project consists of 144 GEM chambers of about 0.5 m2 active area each, employing three GEM foils per chamber, to be installed in the forward region of the CMS endcap during the long shutdown of LHC in 2108-2019. The large active area of each GE1/1 chamber consists of GEM foils that are mechanically stretched in order to secure their flatness and the consequent uniform performance of the GE1/1 chamber across its whole active surface. So far FBGs have been used in high energy physics mainly as high precision positioning and re-positioning sensors and as low cost, easy to mount, low space consuming temperature sensors. FBGs are also commonly used for very precise strain measurements in material studies. In this work we present a novel use of FBGs as flatness and mechanical tensioning sensors applied to the wide GEM foils of the GE1/1 chambers. A network of FBG sensors have been used to determine the optimal mechanical tension applied and to characterise the mechanical tension that should be applied to the foils. We discuss the results of the test done on a full-sized GE1/1 final prototype, the studies done to fully characterise the GEM material, how this information was used to define a standard assembly procedure and possible future developments.Comment: 4 pages, 4 figures, presented by Luigi Benussi at MPGD 2015 (Trieste, Italy). arXiv admin note: text overlap with arXiv:1512.0848

    Development and performance of Triple-GEM detectors for the upgrade of the muon system of the CMS experiment

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    The CMS Collaboration is evaluating GEM detectors for the upgrade of the muon system. This contribution will focus on the R&D performed on chambers design features and will discuss the performance of the upgraded detector

    Design of a constant fraction discriminator for the VFAT3 front-end ASIC of the CMS GEM detector

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    In this work the design of a constant fraction discriminator (CFD) to be used in the VFAT3 chip for the read-out of the triple-GEM detectors of the CMS experiment, is described. A prototype chip containing 8 CFDs was implemented using 130 nm CMOS technology and test results are shown. © CERN 2016

    The LBNO long-baseline oscillation sensitivities with two conventional neutrino beams at different baselines

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    The proposed Long Baseline Neutrino Observatory (LBNO) initially consists of 20\sim 20 kton liquid double phase TPC complemented by a magnetised iron calorimeter, to be installed at the Pyh\"asalmi mine, at a distance of 2300 km from CERN. The conventional neutrino beam is produced by 400 GeV protons accelerated at the SPS accelerator delivering 700 kW of power. The long baseline provides a unique opportunity to study neutrino flavour oscillations over their 1st and 2nd oscillation maxima exploring the L/EL/E behaviour, and distinguishing effects arising from δCP\delta_{CP} and matter. In this paper we show how this comprehensive physics case can be further enhanced and complemented if a neutrino beam produced at the Protvino IHEP accelerator complex, at a distance of 1160 km, and with modest power of 450 kW is aimed towards the same far detectors. We show that the coupling of two independent sub-MW conventional neutrino and antineutrino beams at different baselines from CERN and Protvino will allow to measure CP violation in the leptonic sector at a confidence level of at least 3σ3\sigma for 50\% of the true values of δCP\delta_{CP} with a 20 kton detector. With a far detector of 70 kton, the combination allows a 3σ3\sigma sensitivity for 75\% of the true values of δCP\delta_{CP} after 10 years of running. Running two independent neutrino beams, each at a power below 1 MW, is more within today's state of the art than the long-term operation of a new single high-energy multi-MW facility, which has several technical challenges and will likely require a learning curve.Comment: 21 pages, 12 figure
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