804 research outputs found
The protoMIRAX Hard X-ray Imaging Balloon Experiment
The protoMIRAX hard X-ray imaging telescope is a balloon-borne experiment
developed as a pathfinder for the MIRAX satellite mission. The experiment
consists essentially in a coded-aperture hard X-ray (30-200 keV) imager with a
square array (1313) of 2mm-thick planar CZT detectors with a total area
of 169 cm. The total, fully-coded field-of-view is and the angular resolution is 143'. In this paper we
describe the protoMIRAX instrument and all the subsystems of its balloon
gondola, and we show simulated results of the instrument performance. The main
objective of protoMIRAX is to carry out imaging spectroscopy of selected bright
sources to demonstrate the performance of a prototype of the MIRAX hard X-ray
imager. Detailed background and imaging simulations have been performed for
protoMIRAX balloon flights. The 3 sensitivity for the 30-200 keV range
is ~1.9 10 photons cm s for an integration time
of 8 hs at an atmospheric depth of 2.7 g cm and an average zenith angle
of 30. We have developed an attitude control system for the balloon
gondola and new data handling and ground systems that also include prototypes
for the MIRAX satellite. We present the results of Monte Carlo simulations of
the camera response at balloon altitudes, showing the expected background level
and the detailed sensitivity of protoMIRAX. We also present the results of
imaging simulations of the Crab region. The results show that protoMIRAX is
capable of making spectral and imaging observations of bright hard X-ray source
fields. Furthermore, the balloon observations will carry out very important
tests and demonstrations of MIRAX hardware and software in a near space
environment.Comment: 9 pages, 13 figures, accepted for publication in Astronomy &
Astrophysic
Significado do anti-HBc isolado em doadores de sangue de São Paulo
The clinical significance of isolated anti-HBc is still a challenge. To elucidate the real importance of this finding in our blood donors, an investigation algorithm was tested. One hundred and twelve isolated anti-HBc seropositive blood donors underwent clinical evaluation and retesting of HBV markers. Those who presented repeatedly reactive isolated anti-HBc, received a single dose of hepatitis B recombinant vaccine to verify anti-HBs early response. A HBV-DNA determination by PCR was done for those who did not test positive to anti-HBs after vaccine. The level of anti-HBc was recorded as a ratio of the sample-to-cut-off values (S:C ratio) in 57 candidates at donation. Comparing true and false-positive anti-HBc results, the different S:C ratios of them were statistically significant and when less than 2, implying in a false-positive result probability over 80%. A high percent of false-positive results (16.07%) was verified after anti-HBc retesting. HBV immunity was characterized in 49.11%, either by anti-HBs detection in retesting (15.18%), or after a single dose HBV vaccination (33.93%). HBV-DNA was negative in all tested donors. In conclusion, this algorithm was useful to clarify the meaning of isolated anti-HBc in most of our blood donors.O significado do anti-HBc isolado continua a ser tema relevante para aqueles envolvidos com o atendimento a doadores de sangue soropositivos. Um algoritmo de investigação foi testado com o objetivo de avaliar em nosso meio o real diagnóstico desses doadores. Cento e doze doadores com anti-HBc isolado foram submetidos a avaliação clínico-epidemiológica e testes sorológicos para o VHB. Aqueles confirmadamente anti-HBc isolado, receberam dose única da vacina recombinante contra o VHB, e após 30 dias foi pesquisada a formação do anti-HBs. Naqueles que não formaram anti-HBs após vacina, foi realizada a pesquisa do HBV-DNA por PCR. O índice do "cut-off" sobre a densidade ótica foi determinado em 57 indivíduos por ocasião da doação. Na comparação entre falsos e verdadeiros anti-HBc positivos, o índice C.O./D.O. mostrou significância estatística. Assim quando este índice foi menor que 2, a possibilidade de resultado falso-positivo foi de 83,33%. Verificamos ainda elevada porcentagem de resultados falsos-positivos (16,07%) após a simples repetição do anti-HBc. Imunidade ao VHB pôde ser caracterizada em 49,11%, tanto pela detecção do anti-HBs nos testes de repetição (15,18%) quanto pela vacinação em dose única contra a hepatite B (33,93%). O HBV-DNA foi negativo em todos os doadores testados. Concluímos que este algorítmo foi útil para esclarecer o significado do anti-HBc isolado na maioria dos doadores de sangue estudados
The DECam Ecliptic Exploration Project (DEEP) II. Observational Strategy and Design
We present the DECam Ecliptic Exploration Project (DEEP) survey strategy
including observing cadence for orbit determination, exposure times, field
pointings and filter choices. The overall goal of the survey is to discover and
characterize the orbits of a few thousand Trans-Neptunian Objects (TNOs) using
the Dark Energy Camera (DECam) on the Cerro Tololo Inter-American Observatory
(CTIO) Blanco 4 meter telescope. The experiment is designed to collect a very
deep series of exposures totaling a few hours on sky for each of several 2.7
square degree DECam fields-of-view to achieve a magnitude of about 26.2 using a
wide VR filter which encompasses both the V and R bandpasses. In the first
year, several nights were combined to achieve a sky area of about 34 square
degrees. In subsequent years, the fields have been re-visited to allow TNOs to
be tracked for orbit determination. When complete, DEEP will be the largest
survey of the outer solar system ever undertaken in terms of newly discovered
object numbers, and the most prolific at producing multi-year orbital
information for the population of minor planets beyond Neptune at 30 au.Comment: 29 pages, 4 figures and 4 table
Workflow in Clinical Trial Sites & Its Association with Near Miss Events for Data Quality: Ethnographic, Workflow & Systems Simulation
10.1371/journal.pone.0039671PLoS ONE76
Measurement of differential cross sections for top quark pair production using the lepton plus jets final state in proton-proton collisions at 13 TeV
National Science Foundation (U.S.
Particle-flow reconstruction and global event description with the CMS detector
The CMS apparatus was identified, a few years before the start of the LHC operation at CERN, to feature properties well suited to particle-flow (PF) reconstruction: a highly-segmented tracker, a fine-grained electromagnetic calorimeter, a hermetic hadron calorimeter, a strong magnetic field, and an excellent muon spectrometer. A fully-fledged PF reconstruction algorithm tuned to the CMS detector was therefore developed and has been consistently used in physics analyses for the first time at a hadron collider. For each collision, the comprehensive list of final-state particles identified and reconstructed by the algorithm provides a global event description that leads to unprecedented CMS performance for jet and hadronic tau decay reconstruction, missing transverse momentum determination, and electron and muon identification. This approach also allows particles from pileup interactions to be identified and enables efficient pileup mitigation methods. The data collected by CMS at a centre-of-mass energy of 8 TeV show excellent agreement with the simulation and confirm the superior PF performance at least up to an average of 20 pileup interactions
Pseudorapidity and transverse momentum dependence of flow harmonics in pPb and PbPb collisions
info:eu-repo/semantics/publishe
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