3,021 research outputs found
Large Size Telescope camera support structures for the Cherenkov Telescope Array
The design of the camera support structures for the Cherenkov Telescope Array
(CTA) Large Size Telescopes (LSTs) is based on an elliptical arch geometry
reinforced along its orthogonal projection by two symmetric sets of stabilizing
ropes. The main requirements in terms of minimal camera displacement, minimal
weight, minimal shadowing on the telescope mirror, maximal strength of the
structures and fast dynamical stabilization have led to the application of
Carbon Fibre Plastic Reinforced (CFPR) technologies. This work presents the
design, static and dynamic performance of the telescope fulfilling critical
specifications for the major scientific objectives of the CTA LST, e.g. Gamma
Ray Burst detection.Comment: In Proceedings of the 33rd International Cosmic Ray Conference
(ICRC2013), Rio de Janeiro (Brazil). All CTA contributions at arXiv:1307.223
Young star clusters as gamma ray emitters and their detection with Cherenkov Telescopes
Young massive star clusters as sites of strong stellar winds and supernova explosions may accelerate charged particles at high energies and produce gamma-rays. These sources may also contribute to the production of cosmic rays in our galaxy. At TeV energies several candidates have already been detected: Cygnus OB2, Westerlund 1 \& 2, W43, Pismis 22 and W49A. Our study addresses the issue of very young star clusters where no supernova has occurred yet. During the lifetime of a massive star (M), supersonic stellar winds do indeed release as much energy as a supernova explosion. As supernova remnants are already known as gamma-ray emitters our purpose is to avoid any ambiguity on the origin of a possible gamma ray emission and to fully assume a stellar wind contribution. In this work we first present a catalogue of potential gamma-ray emitting clusters and discuss the criteria used to built the catalogue. We hence model the expected energetic particle spectrum including escapes and losses. We deduce gamma-ray luminosities produced by Inverse Compton and pion decay emission of each cluster and their associated HII regions. We finally compare these gamma-ray luminosities with HESS-II and CTA Cherenkov telescopes sensitivities
A method to localize gamma-ray bursts using POLAR
The hard X-ray polarimeter POLAR aims to measure the linear polarization of
the 50-500 keV photons arriving from the prompt emission of gamma-ray bursts
(GRBs). The position in the sky of the detected GRBs is needed to determine
their level of polarization. We present here a method by which, despite of the
polarimeter incapability of taking images, GRBs can be roughly localized using
POLAR alone. For this purpose scalers are attached to the output of the 25
multi-anode photomultipliers (MAPMs) that collect the light from the POLAR
scintillator target. Each scaler measures how many GRB photons produce at least
one energy deposition above 50 keV in the corresponding MAPM. Simulations show
that the relative outputs of the 25 scalers depend on the GRB position. A
database of very strong GRBs simulated at 10201 positions has been produced.
When a GRB is detected, its location is calculated searching the minimum of the
chi2 obtained in the comparison between the measured scaler pattern and the
database. This GRB localization technique brings enough accuracy so that the
error transmitted to the 100% modulation factor is kept below 10% for GRBs with
fluence Ftot \geq 10^(-5) erg cm^(-2) . The POLAR localization capability will
be useful for those cases where no other instruments are simultaneously
observing the same field of view.Comment: 13 pages, 10 figure
Host tissue proteomics reveal insights into the molecular basis of Schistosoma haematobium-induced bladder pathology.
Urogenital schistosomiasis remains a major public health concern worldwide. In response to egg deposition, the host bladder undergoes gross and molecular morphological changes relevant for disease manifestation. However, limited mechanistic studies to date imply that the molecular mechanisms underlying pathology are not well-defined. We leveraged a mouse model of urogenital schistosomiasis to perform for the first time, proteome profiling of the early molecular events that occur in the bladder after exposure to S. haematobium eggs, and to elucidate the protein pathways involved in urogenital schistosomiasis-induced pathology. Purified S. haematobium eggs or control vehicle were microinjected into the bladder walls of mice. Mice were sacrificed seven days post-injection and bladder proteins isolated and processed for proteome profiling using mass spectrometry. We demonstrate that biological processes including carcinogenesis, immune and inflammatory responses, increased protein translation or turnover, oxidative stress responses, reduced cell adhesion and epithelial barrier integrity, and increased glucose metabolism were significantly enriched in S. haematobium infection. S. haematobium egg deposition in the bladder results in significant changes in proteins and pathways that play a role in pathology. Our findings highlight the potential bladder protein indicators for host-parasite interplay and provide new insights into the complex dynamics of pathology and characteristic bladder tissue changes in urogenital schistosomiasis. The findings will be relevant for development of improved interventions for disease control
Searching for galactic axions through magnetized media: QUAX status report
The current status of the QUAX R\&D program is presented. QUAX is a
feasibility study for a detection of axion as dark matter based on the coupling
to the electrons. The relevant signal is a magnetization change of a magnetic
material placed inside a resonant microwave cavity and polarized with a static
magnetic field.Comment: Contributed to the 13th Patras Workshop on Axions, WIMPs and WISPs,
Thessaloniki, May 15 to 19, 201
Peri-Conceptional Intake of Folic Acid Supplement to Date: A Medical-Legal Issue
Folic Acid (FA) supplementation during pregnancy represents a so widespread and established recommendation all over the world, to be taken for granted sometimes. As a matter of fact, this vitamin supplement is worldwide recommended mostly during peri-conceptional period for its proved preventive effect on Neural Tubal Defects (NTDs), like spina bifida. However, The biological and clinical potential of FA is reassessing and this represents a hot topic in scientific community, mostly in consideration of the possible medical-legal implications. An overview is mandatory in order to keep in mind FA-related possibl
Effectiveness of an innovative sensory approach to improve childrenâs nutritional choices
A case-control study was conducted to investigate the effectiveness of the EdueatÂź Method, through experiential workshops focused on the use of all 5 senses. In two different primary schools in the same city, questionnaires were administered in two months with a follow-up one year later. Participants: 119 children (age 8.2â9.0) chosen randomly; control group 66 (55.5%). Seven lessons of 2 h each were held in the schools by experts of the EdueatÂź method and seven extra lessons by the teachers. The main outcome measures were the childrenâs changes in their approach and attitude towards their eating habits. The answers were grouped with factor analysis and summarized through scores. Repeated-measures analysis of variance was conducted in order to identify the relationships between scores and treatment over time. At the end of treatment, the intervention group showed a significant appreciation towards healthy foods (+4.15 vs. â0.05, p = 0.02) and a greater capacity in identifying foods which are very good for the health (+15.6 vs. +14.4, p = 0.02). In conclusion, the EdueatÂź method was found to be particularly promising in transmitting knowledge of those foods which are healthy. Greater involvement of teachers and parents is crucial
Epicardial adipose tissue measured by magnetic resonance imaging predicts abnormal adenosine stress cardiovascular magnetic resonance imaging and future adverse cardiovascular events
Background A growing body of evidence demonstrates a quantitative association between Epicardial Adipose Tissue (EAT), cardiometabolic risk factors and measures of coronary artery disease (CAD). It is still unclear, however, if EAT is predictive of abnormal functional stress tests and clinical outcomes. The aim of this study is to elucidate the relationship between the total volume of EAT, the detection of ischemia and/or infarct with Adenosine Stress Cardiovascular Magnetic Resonance imaging (AS-CMR), and combined future adverse cardiovascular events. Method
POLAR, an instrument to measure GRB polarization. Design and laboratory tests.
International audienceReliable polarization measurements of photons from Gamma Ray Bursts (GRB) would make the understanding of the GRB phenomenon progress enormously. POLAR is a concept for an instrument that would enable such a measurement. We report about performances predicted by of Monte-Carlo and on laboratory tests to validate some critical aspects of the desig
POLAR: a space borne GRB polarimeter
International audienceThe direction and the level of polarization of high energy photons emitted by astrophysics sources are valuable observables for the understanding of the corresponding emission mechanisms, source geometry and strength of magnetic fields at work. POLAR is a novel compact space-borne detector conceived for a precise measurement of hard X-ray polarization and optimized for the detection of Gamma-Ray Burst (GRB) photons in the energy range 50-500 keV. In POLAR, the GRB photons undergo Compton scattering in a target made out of 1600 plastic scintillator bars. The azimuthal distribution of the scattered photons inside the target provides the information on the GRB polarization. The target is divided into 5x5 units, each one consisting of 8x8 scintillator bars optically coupled with a multi-anode photomultiplier. POLAR, thanks to its large modulation factor (mu_100=40%), its large effective area (Aeff = 250 cm2), and its large field of view ( 1/3 of the sky) will be able to determine the degree and angle of polarization of a strong GRB with a minimum detectable polarization of less than 10% (3sigma). In this communication the present design and status of the POLAR project is presented. Expected results through deep Monte Carlo simulation studies as well as the recent results of laboratory measurements are detailed
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