AGILE, the Italian space mission dedicated to gamma-ray and hard-X astrophysics, was succesfully launched on 23 April 2007 and is currently fully operative. AGILE is placed in an equatorial Low-Earth ...Orbit, at 550 km altitude with 2.46 degrees inclination. The Mini-Calorimeter (MCAL) on-board AGILE is a scintillation detector made of 30 CsI(Tl) bars with photodiode readout at both ends, arranged in two orthogonal layers, for a total amount of 20 kg of active material, an on-axis geometrical area of 1400 cm 2 and a thickness of 1.5 radiation lengths. MCAL can work both as a slave of the AGILE Silicon tracker and as an independent detector for gamma-ray burst (GRB) detection in the 300 keV - 200 MeV energy range. If a trigger is issued by a dedicated onboard logic, data are dowloaded in photon-by-photon mode with a time resolution of 2σs allowing complete spectral and timing analysis of the event, limited by counting statistics only. Moreover, 11 band energy spectra with 1 second time resolution (scientific ratemeters) are continuously integrated on-board and sent to telemetry for background monitoring. MCAL is currently one of the three detectors in space with microsecond timing accuracy in the MeV range, with a detection rate of 1 GRB/week. The performance of the instrument after 18 months of in orbit operations will be discussed, as well as the scientific results achieved.
The energy range between 10 and 50 MeV is an experimentally very difficult range and remained uncovered since the time of COMPTEL. Here we propose a possible mission to cover this energy range.
The mini-calorimeter for the AGILE satellite Labanti, C.; Argan, A.; Bulgarelli, A. ...
IEEE Symposium Conference Record Nuclear Science 2004,
2004, Volume:
1
Conference Proceeding
AGILE is a small space mission of the Italian Space Agency (ASI) devoted to observations for astrophysics in the gamma-ray energy range 30 MeV-50 GeV with a simultaneous window in the X-ray band 10 ...keV-40 keV. AGILE payload is made of a tungsten-silicon tracker, a CsI mini-calorimeter for the high energy band and a silicon based X-ray detector (SuperAgile); an anticoincidence system carries out background rejection. In the gamma-ray's band the satellite will have a field of view of about 1/5 of the sky, with angular resolution of a few arc-minutes and good timing resolution. For the high energy AGILE detection principle is based on the pair production process that arises from the interaction between photons and the tungsten layers above the silicon tracker. The silicon tracker is designed to determine the direction of the incoming radiation, while the mini-calorimeter evaluates the energy of the interacting photons and particles. For the detection of transients and gamma-ray burst events, the mini-calorimeter will also work as a stand-alone gamma-ray detector, with no imaging capabilities, covering the energy range 250 keV-250 MeV. The mini-calorimeter is made of an array of position sensitive CsI(Tl) scintillator bars with photodiode read-out. The characteristics of its detector elements and the front end electronics signal processing allow a moderate position reconstruction of the detected event. In this paper a description of the mini-calorimeter is reported as well as a summary of performances reached with the pre-flight instrument models already built and tested.
High-energy phenomena in the cosmos, and in particular processes leading to the emission of gamma- rays in the energy range 10 MeV - 100 GeV, play a very special role in the understanding of our ...Universe. This energy range is indeed associated with non-thermal phenomena and challenging particle acceleration processes. The technology involved in detecting gamma-rays is challenging and drives our ability to develop improved instruments for a large variety of applications. GAMMA-LIGHT is a Small Mission which aims at an unprecedented advance of our knowledge in many sectors of astrophysical and Earth studies research. The Mission will open a new observational window in the low-energy gamma-ray range 10-50 MeV, and is configured to make substantial advances compared with the previous and current gamma-ray experiments (AGILE and Fermi). The improvement is based on an exquisite angular resolution achieved by GAMMA-LIGHT using state-of-the-art Silicon technology with innovative data acquisition. GAMMA-LIGHT will address all astrophysics issues left open by the current generation of instruments. In particular, the breakthrough angular resolution in the energy range 100 MeV - 1 GeV is crucial to resolve patchy and complex features of diffuse sources in the Galaxy as well as increasing the point source sensitivity. This proposal addresses scientific topics of great interest to the community, with particular emphasis on multifrequency correlation studies involving radio, optical, IR, X-ray, soft gamma-ray and TeV emission. At the end of this decade several new observatories will be operational including LOFAR, SKA, ALMA, HAWK, CTA. GAMMA-LIGHT will "fill the vacuum" in the 10 MeV-10 GeV band, and will provide invaluable data for the understanding of cosmic and terrestrial high-energy sources.
CBS is a new program for binary system light curve analysis, it generates
synthetic light curves for a binary system, accounting for eclipses, tidal
distortion, limb darkening, gravity darkening and ...reflection; it is also
possible to compute the light contribution and eclipses of an accretion disk.
The bolometric light curve is generated, as well as curves for the U,B,V,R,I
colour bands. In the following we give a brief description of the first version
of the program and show some preliminary results.
CBS is a new program for binary system light curve analysis, it generates synthetic light curves for a binary system, accounting for eclipses, tidal distortion, limb darkening, gravity darkening and ...reflection; it is also possible to compute the light contribution and eclipses of an accretion disk. The bolometric light curve is generated, as well as curves for the U,B,V,R,I colour bands. In the following we give a brief description of the first version of the program and show some preliminary results.
Background:
Magnetic resonance (MR) imaging is the most common modality for assessment of the rotator cuff before and after surgery. Several classifications have been described aiming to define main ...tear characteristics. However, there is still confusion when it comes to the reliability of those classifications.
Purpose:
(1) To identify all MR classifications available in the literature for preoperative assessment of rotator cuff tears, (2) to summarize available data on the reliability of identified classifications, and (3) to assess the methodological quality of reliability studies.
Study Design:
Systematic review; Level of evidence, 4.
Methods:
This systematic review was conducted following the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. All studies reporting MR assessment in patients with a superior or posterosuperior rotator cuff tear were included. After identification of the available MR criteria, reliability studies were analyzed. Descriptive statistics were used to summarize findings. Methodological quality was assessed using the Quality Appraisal of Reliability Studies checklist.
Results:
A total of 75 studies were included in this review. Eight categories of outcomes could be identified. Of the total, 62 studies reported interobserver reliability whereas 32 reported intraobserver reliability of some of the identified criteria. Each category reflected a variety of reliability, ranging from poor to excellent agreement. MR proved to be a reliable imaging modality to detect the structural integrity of the posterosuperior cuff, especially in cases of full-thickness tear; it was also reliable in terms of tear width and length and muscle atrophy based on a tangent sign or Thomazeau classification. All other classifications did not prove acceptable reliability. Methodological quality was high for 23 articles and moderate for 14.
Conclusion:
Preoperative MR is a reliable imaging modality to identify full-thickness tears, measure tear size and morphology, and identify muscle atrophy with tangent sign or Thomazeau classification. All other outcomes and classifications did not show acceptable reliability; therefore, caution is needed when using them for preoperative evaluation of a rotator cuff tear.
Measuring the thermal conductivity (κ) of water at extreme conditions is a challenging task, and few experimental data are available. We predict κ for temperatures and pressures relevant to the ...conditions of the Earth mantle, between 1,000 and 2,000 K and up to 22 GPa. We employ close to equilibrium molecular dynamics simulations and a deep neural network potential fitted to density functional theory data. We then interpret our results by computing the equation of state of water on a fine grid of points and using a simple model for κ. We find that the thermal conductivity is weakly dependent on temperature and monotonically increases with pressure with an approximate square-root behavior. In addition, we show how the increase of κ at high pressure, relative to ambient conditions, is related to the corresponding increase in the sound velocity. Although the relationships between the thermal conductivity, pressure and sound velocity established here are not rigorous, they are sufficiently accurate to allow for a robust estimate of the thermal conductivity of water in a broad range of temperatures and pressures, where experiments are still difficult to perform.
We present a method based on sinusoidal approach to equilibrium molecular dynamics (SAEMD) to compute the thermal conductivity of liquids Similar to nonequilibrium molecular dynamics, and unlike ...equilibrium simulations based on the Green-Kubo formalism, the method only requires the calculation of forces and total energies. The evaluation of heat fluxes and energy densities is not necessary, thus offering the promise of efficiently implementing first principles simulations based on density functional theory or deep molecular dynamics. Our approach is a generalization of SAEMD for solids, where the thermal conductivity is computed in the steady state, instead of a transient regime, thus properly taking into account diffusive terms in the heat equation. We present results for liquid water at ambient conditions and under pressure and discuss simulation requirements to obtain converged values of the thermal conductivity as a function of size and simulation time.
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