500 research outputs found
Analytical study of electrical disconnect system for use on manned and unmanned missions
The objective of this contract is to establish an optimum electrical disconnect system design(s) for use on manned and unmanned missions. The purpose of the disconnect system is to electrically mate and demate the spacecraft to subsystem module interfaces to accomplish orbital operations. The results of Task 1 and Task 2 of the effort are presented. Task 1 involves the definition of the functional, operational, and environmental requirements for the connector system to support the leading prototype candidate concepts. Task 2 involves the documentation review and survey of available existing connector designs
Mental health care for irregular migrants in Europe: Barriers and how they are overcome
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use,
distribution, and reproduction in any medium, provided the original work is properly cited
Sensitivity to Gravitational Waves from Compact Binary Coalescences Achieved during LIGO's Fifth and Virgo's First Science Run
We summarize the sensitivity achieved by the LIGO and Virgo gravitational
wave detectors for compact binary coalescence (CBC) searches during LIGO's
fifth science run and Virgo's first science run. We present noise spectral
density curves for each of the four detectors that operated during these
science runs which are representative of the typical performance achieved by
the detectors for CBC searches. These spectra are intended for release to the
public as a summary of detector performance for CBC searches during these
science runs.Comment: 12 pages, 5 figure
Virgo calibration and reconstruction of the gravitational wave strain during VSR1
Virgo is a kilometer-length interferometer for gravitational waves detection
located near Pisa. Its first science run, VSR1, occured from May to October
2007. The aims of the calibration are to measure the detector sensitivity and
to reconstruct the time series of the gravitational wave strain h(t). The
absolute length calibration is based on an original non-linear reconstruction
of the differential arm length variations in free swinging Michelson
configurations. It uses the laser wavelength as length standard. This method is
used to calibrate the frequency dependent response of the Virgo mirror
actuators and derive the detector in-loop response and sensitivity within ~5%.
The principle of the strain reconstruction is highlighted and the h(t)
systematic errors are estimated. A photon calibrator is used to check the sign
of h(t). The reconstructed h(t) during VSR1 is valid from 10 Hz up to 10 kHz
with systematic errors estimated to 6% in amplitude. The phase error is
estimated to be 70 mrad below 1.9 kHz and 6 micro-seconds above.Comment: 8 pages, 8 figures, proceedings of Amaldi 8 conference, to be
published in Journal of Physics Conference Series (JPCS). Second release:
correct typo
Clear-PEM: A PET imaging system dedicated to breast cancer diagnostics
The Clear-PEM scanner for positron emission mammography under development is described. The detector is based on pixelized LYSO crystals optically coupled to avalanche photodiodes and readout by a fast low-noise electronic system. A dedicated digital trigger (TGR) and data acquisition (DAQ) system is used for on-line selection of coincidence events with high efficiency, large bandwidth and small dead-time. A specialized gantry allows to perform exams of the breast and of the axilla. In this paper we present results of the measurement of detector modules that integrate the system under construction as well as the imaging performance estimated from Monte Carlo simulated data.http://www.sciencedirect.com/science/article/B6TJM-4M942B5-D/1/e8aea93baa1aeae3538ea200a5a5466
Directional limits on persistent gravitational waves using LIGO S5 science data
The gravitational-wave (GW) sky may include nearby pointlike sources as well
as astrophysical and cosmological stochastic backgrounds. Since the relative
strength and angular distribution of the many possible sources of GWs are not
well constrained, searches for GW signals must be performed in a
model-independent way. To that end we perform two directional searches for
persistent GWs using data from the LIGO S5 science run: one optimized for
pointlike sources and one for arbitrary extended sources. The latter result is
the first of its kind. Finding no evidence to support the detection of GWs, we
present 90% confidence level (CL) upper-limit maps of GW strain power with
typical values between 2-20x10^-50 strain^2 Hz^-1 and 5-35x10^-49 strain^2
Hz^-1 sr^-1 for pointlike and extended sources respectively. The limits on
pointlike sources constitute a factor of 30 improvement over the previous best
limits. We also set 90% CL limits on the narrow-band root-mean-square GW strain
from interesting targets including Sco X-1, SN1987A and the Galactic Center as
low as ~7x10^-25 in the most sensitive frequency range near 160 Hz. These
limits are the most constraining to date and constitute a factor of 5
improvement over the previous best limits.Comment: 10 pages, 4 figure
Medicine is patriarchal, but alternative medicine is not the answer
Women are over-represented within alternative medicine, both as consumers and as service providers. In this paper, I show that the appeal of alternative medicine to women relates to the neglect of women’s health needs within scientific medicine. This is concerning because alternative medicine is severely limited in its therapeutic effects; therefore, those who choose alternative therapies are liable to experience inadequate healthcare. I argue that while many patients seek greater autonomy in alternative medicine, the absence of an evidence base and plausible mechanisms of action leaves patients unable to realize meaningful autonomy. This seems morally troubling, especially given that the neglect of women’s needs within scientific medicine seems to contribute to preferences for alternative medicine. I conclude that the liberatory credentials of alternative medicine should be questioned and make recommendations to render scientific medicine better able to meet the needs of typical alternative medicine consumers
Assessing the impact of small amounts of water and iron oxides on adhesion in the wheel/rail interface using High Pressure Torsion testing
A new High Pressure Torsion (HPT) set-up has been developed for assessing the effect of third body materials in the wheel/rail interface in a representative and controlled manner. In this study the technique has been used to investigate the effect of small amounts of water and iron oxides mixtures when subjected to different contact pressures. HPT tests showed reduction in adhesion relative to a dry contact when testing with small amounts of water and/or oxides, however sustained low adhesion (μ<0.05) was not produced. To aid interpretation of the results a model has been developed to explore the behavior encountered when testing with water and iron oxide mixtures. The model relates the shear properties of water and oxide mixtures (with increasing solid content) to a predicted adhesion. The model shows a narrow window of water to oxide fraction is required for reduced adhesion, particularly on rough surfaces, and this correlates with the behavior observed
On the invertibility of matrices with a double saddle-point structure
We establish necessary and sufficient conditions for invertibility of symmetric three-by-three block matrices having a double saddle-point structure \fb{that guarantee the unique solvability of double saddle-point systems}. We consider various scenarios, including the case where all diagonal blocks are allowed to be rank deficient. Under certain conditions related to the nullity of the blocks and intersections of their kernels, an explicit formula for the inverse is derived
Segmentation-based regularization of dynamic SPECT reconstructions
Abstract-Dynamic SPECT reconstruction using a single slow camera rotation is a highly underdetermined problem, which requires the use of regularization techniques to obtain useful results. The dSPECT algorithm We test this approach with a digital phantom simulating the kinetics of Tc99m-DTPA in the renal system, including healthy and unhealthy behaviour. Summed TACs for each kidney and the bladder were calculated for the spatially regularized and nonregularized reconstructions, and compared to the true values. The TACs for the two kidneys were noticeably improved in every case, while TACs for the smaller bladder region were unchanged. Furthermore, in two cases where the segmentation was intentionally done incorrectly, the spatially regularized reconstructions were still as good as the non-regularized ones. In general, the segmentation-based regularization improves TAC quality within ROIs, as well as image contrast
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