First results of a cryogenic optical photon counting imaging spectrometer using a DROID array

Context. In this paper we present the first system test in which we demonstrate the concept of using an array of Distributed Read Out Imaging Devices (DROIDs) for optical photon detection. Aims. After the successful S-Cam 3 detector the next step in the development of a cryogenic optical photon counting imaging spectrometer under the S-Cam project is to increase the field of view using DROIDs. With this modification the field of view of the camera has been increased by a factor of 5 in area, while keeping the number of readout channels the same. Methods. The test has been performed using the flexible S-Cam 3 system and exchanging the 10x12 Superconducting Tunnel Junction array for a 3x20 DROID array. The extra data reduction needed with DROIDs is performed offline. Results. We show that, although the responsivity (number of tunnelled quasiparticles per unit of absorbed photon energy, e- /eV) of the current array is too low for direct astronomical applications, the imaging quality is already good enough for pattern detection, and will improve further with increasing responsivity. Conclusions. The obtained knowledge can be used to optimise the system for the use of DROIDs.Comment: 7 pages, 9 figures, accepted for publicaiton in A&

The Public Administration Performance Appraisal Integrated System (SIADAP) and the Portuguese civil servants perceptions

As part of managerial reform process, in 2004 the Public Administration Performance Appraisal Integrated System (SIADAP) was set up in Portugal. This study aimed to analyze the perceptions of Portuguese civil servants on this appraisal system. A second drive was to understand how those perceptions change depending on what extent the model is perceived as fair or not. A survey was carried out and data were collected from 2066 civil servants, including managers. The results show very negative perceptions, in particular regarding SIADAP’s objectivity, transparency and fairness. Also, Kruskal-Wallis tests and post-hoc paired comparisons reveal that civil servants who see the system as “unfair” tend to have more negative perceptions on it than those who see it as “fair” or those who are not sure about the fairness of the system.info:eu-repo/semantics/acceptedVersio

Main Fuel Cells mathematical models: Comparison and analysis in terms of free parameters

This paper resumes the main mathematical models of Fuel Cells (PEM models). In particular, a comparison study of the various models introduced in the technical literature is presented and the dependency of the various model parameters is analyzed in different operating conditions. As the manifold of the model parameter is very wide and their determination is difficult, it is mandatory to introduce approximations and simplifications on which each model is based. The novelty of this work is the organization of the existing models in three categories with regard to the number of free parameters and to the dependency of such parameters on the different running conditions and the usage of a reference model in order to compare the difference between the latter once both in terms of fast execution of the simulation and care of the simulation results

Reducing variability in conditions for cell handling improves MSC yields

Efficient cell expansion in vitro is essential to commercialization of human MSC as a cellular therapy. The cost of goods sold (COGS) is dramatically affected by how long it takes to expand the cells in vitro and the cell yield determines the number of doses generated for profit. Therefore, maximizing MSC growth in culture is critical for the success of MSC-based cellular therapies. Studies by others have shown that temperature differences in cell production can adversely affect cell yields. Here we study the effects of variability in temperature and CO2, like changes seen during routine cell handling in a room air BSC, on human MSC yield. We cultured human bone marrow mesenchymal stromal/stem cells for 8 biweekly subpassages (P4-P12) with conventional room air CO2 incubator conditions (37 degrees C/ 5% CO2). The culture was divided into separate cultures for routine cell handling in two different conditions (1) room air BSC conditions (RT/ 0.1% CO2) (variable) or (2) the same conditions as incubation (constant). At each passage, cells were plated in 96-well plates which were assayed over time for cell growth kinetics. Consistently, MSC incubated and handled in constant conditions recovered more quickly after subpassage and were more likely to continue to divide, improving final cell yields. We conclude that constant conditions for cell handling are critical for maximum MSC cell yield

Gamma-ray burst observations with new generation imaging atmospheric Cerenkov Telescopes in the FERMI era

After the launch and successful beginning of operations of the FERMI satellite, the topics related to high-energy observations of gamma-ray bursts have obtained a considerable attention by the scientific community. Undoubtedly, the diagnostic power of high-energy observations in constraining the emission processes and the physical conditions of gamma-ray burst is relevant. We briefly discuss how gamma-ray burst observations with ground-based imaging array Cerenkov telescopes, in the GeV-TeV range, can compete and cooperate with FERMI observations, in the MeV-GeV range, to allow researchers to obtain a more detailed and complete picture of the prompt and afterglow phases of gamma-ray bursts.Comment: 9 pages, two figures. Proceeding for the 6th "Science with the New Generation of High Energy Gamma-Ray Experiments" worksho

Novel technique for monitoring the performance of the LAT instrument on board the GLAST satellite

The Gamma-ray Large Area Space Telescope (GLAST) is an observatory designed to perform gamma-ray astronomy in the energy range 20 MeV to 300 GeV, with supporting measurements for gamma-ray bursts from 10 keV to 25 MeV. GLAST will be launched at the end of 2007, opening a new and important window on a wide variety of high energy astrophysical phenomena . The main instrument of GLAST is the Large Area Telescope (LAT), which provides break-through high-energy measurements using techniques typically used in particle detectors for collider experiments. The LAT consists of 16 identical towers in a four-by-four grid, each one containing a pair conversion tracker and a hodoscopic crystal calorimeter, all covered by a segmented plastic scintillator anti-coincidence shield. The scientific return of the instrument depends very much on how accurately we know its performance, and how well we can monitor it and correct potential problems promptly. We report on a novel technique that we are developing to help in the characterization and monitoring of LAT by using the power of classification trees to pinpoint in a short time potential problems in the recorded data. The same technique could also be used to evaluate the effect on the overall LAT performance produced by potential instrumental problems.Comment: 2 pages, 1 figure, manuscript submitted on behalf of the GLAST/LAT collaboration to First GLAST symposium proceeding

A Concept for an STJ-based Spectrograph

We describe a multi-order spectrograph concept suitable for 8m-class telescopes, using the intrinsic spectral resolution of Superconducting Tunneling Junction detectors to sort the spectral orders. The spectrograph works at low orders, 1-5 or 1-6, and provides spectral coverage with a resolving power of R~8000 from the atmospheric cutoff at 320 nm to the long wavelength end of the infrared H or K band at 1800 nm or 2400 nm. We calculate that the spectrograph would provide substantial throughput and wavelength coverage, together with high time resolution and sufficient dynamic range. The concept uses currently available technology, or technologies with short development horizons, restricting the spatial sampling to two linear arrays; however an upgrade path to provide more spatial sampling is identified. All of the other challenging aspects of the concept - the cryogenics, thermal baffling and magnetic field biasing - are identified as being feasible.Comment: Accepted in Monthly Notices of the Royal Astronomical Society, 12 pages with 10 figure

Pengaruh Senam Lansia Terhadap Kadar Kolesterol Total Pada Lansia Di BPLU Senja Cerah Manado

: Many changes occur in the elderly include changes in body composition, muscle, bones and joints, cardiovascular system, respiratory and cognition. One of the efforts to maintain, improve health and physical fitness for the elderly is to exercise. The aim of this research is to know the effect of the elderly gymnastics on the levels of total cholesterol in elderly at BPLU Senja Cerah Manado. This research is experimental study with one group pre-post test design. The research respondents are 18 elderly people in BPLU Senja Cerah Manado. Cholesterol levels are measured before the first gymnastics session and after final gymnastics session. Respondents do gymnastics three times a week for eight weeks. The research results is analyzed by Wilcoxon test using a computer program. The result of the research shows that the mean level of cholesterol before first elderly gymnastics 222,17 mg/dL and after final elderly gymnastics 231,50 mg/dL. There is no significant effect on respondents total cholesterol after doing elderly gymnastics for three times a week for eight weeks

Galactic center at very high-energies

Employing data collected during the first 25 months' observations by the Fermi-LAT, we describe and subsequently seek to model the very high energy (>300 MeV) emission from the central few parsecs of our Galaxy. We analyze the morphological, spectral and temporal characteristics of the central source, 1FGL J1745.6-2900. Remarkably, the data show a clear, statistically significant signal at energies above 10 GeV, where the Fermi-LAT has an excellent angular resolution comparable to the angular resolution of HESS at TeV energies, which makes meaningful the joint analysis of the Fermi and HESS data. Our analysis does not show statistically significant variability of 1FGL J1745.6-2900. Using the combination of Fermi data on 1FGL J1745.6-2900 and HESS data on the coincident, TeV source HESS J1745-290, we show that the spectrum of the central gamma-ray source is inflected with a relatively steep spectral region matching between the flatter spectrum found at both low and high energies. We seek to model the gamma-ray production in the inner 10 pc of the Galaxy and examine, in particular, cosmic ray (CR) proton propagation scenarios that reproduce the observed spectrum of the central source. We show that a model that instantiates a transition from diffusive propagation of the CR protons at low energy to almost rectilinear propagation at high energies (given a reasonable energy-dependence of the assumed diffusion coefficient) can well explain the spectral phenomenology. In general, however, we find considerable degeneracy between different parameter choices which will only be broken with the addition of morphological information that gamma-ray telescopes cannot deliver given current angular resolution limits.We argue that a future analysis done in combination with higher-resolution radio continuum data holds out the promise of breaking this degeneracy.Comment: submitted to Ap