808 research outputs found
High frequency of inadequate test requests for antiphospholipid antibodies in daily clinical practice
Abstract Background: We have empirically noted that many physicians routinely request anti-phospholipid antibodies (aPL) without a correct clinical indication. The aim of this study was to evaluate retrospectively whether aPL testing at our Thrombosis Centre was justified. Methods: Medical records from 520 subjects for aPL screening tests for various clinical conditions were reviewed. The aPL screening tests were: lupus anticoagulant (LA), anti-cardiolipin antibodies (aCL) and anti-β(2) glycoptotein I (aβ(2) GPI). Requests for aPL screening were divided into justified, potentially justified or not adequately justified. Results: aPL testing requests were considered justified in 358 (69%) patients, potentially justified in 66 (12.6%) and not adequately justified in 96 (18.4%). LA was positive in 65 (18%) of justified requests and in only one (1%) of the 96 potentially justified requests. None of the 66 not adequately justified for aPL testing was positive for LA. aβ(2) ..
Neural regulation of cardiovascular response to exercise: role of central command and peripheral afferents
During dynamic exercise, mechanisms controlling the cardiovascular apparatus operate to provide adequate oxygen to fulfill metabolic demand of exercising muscles and to guarantee metabolic end-products washout. Moreover, arterial blood pressure is regulated to maintain adequate perfusion of the vital organs without excessive pressure variations. The autonomic nervous system adjustments are characterized by a parasympathetic withdrawal and a sympathetic activation. In this review, we briefly summarize neural reflexes operating during dynamic exercise. The main focus of the present review will be on the central command, the arterial baroreflex and chemoreflex, and the exercise pressure reflex. The regulation and integration of these reflexes operating during dynamic exercise and their possible role in the pathophysiology of some cardiovascular diseases are also discusse
Constraints on the environment and energetics of the Broad-Line Ic SN2014ad from deep radio and X-ray observations
Broad-line type Ic Supernovae (BL-Ic SNe) are characterized by high ejecta
velocity ( km s) and are sometimes associated with the
relativistic jets typical of long duration ( s) Gamma-Ray Bursts
(L-GRBs). The reason why a small fraction of BL-Ic SNe harbor relativistic jets
is not known. Here we present deep X-ray and radio observations of the BL-Ic
SN2014ad extending from to days post explosion. SN2014ad was not
detected at either frequency and has no observational evidence of a GRB
counterpart. The proximity of SN2014ad ( Mpc) enables very deep
constraints on the progenitor mass-loss rate and on the total energy
of the fast ejecta . We consider two synchrotron emission scenarios for a
wind-like circumstellar medium (CSM): (i) uncollimated non-relativistic ejecta,
and (ii) off-axis relativistic jet. Within the first scenario our observations
are consistent with GRB-less BL-Ic SNe characterized by a modest energy budget
of their fast ejecta ( erg), like SNe 2002ap and 2010ay.
For jetted explosions, we cannot rule out a GRB with erg
(beam-corrected) with a narrow opening angle ()
observed moderately off-axis () and
expanding in a very low CSM density ( M
yr). Our study shows that off-axis low-energy jets expanding in a
low-density medium cannot be ruled out even in the most nearby BL-Ic SNe with
extensive deep observations, and might be a common feature of BL-Ic SNe.Comment: 9 pages, 5 figures, accepted in Ap
Venous-right atrial bypass for superior vena cava thrombosis during orthotopic liver transplantation
Correlated electron-hole plasma in organometal perovskites
Organic-inorganic perovskites are a class of solution-processed semiconductors holding promise for the realization of low-cost efficient solar cells and on-chip lasers. Despite the recent attention they have attracted, fundamental aspects of the photophysics underlying device operation still remain elusive. Here we use photoluminescence and transmission spectroscopy to show that photoexcitations give rise to a conducting plasma of unbound but Coulomb-correlated electron-hole pairs at all excitations of interest for light-energy conversion and stimulated optical amplification. The conductive nature of the photoexcited plasma has crucial consequences for perovskite-based devices: in solar cells, it ensures efficient charge separation and ambipolar transport while, concerning lasing, it provides a low threshold for light amplification and justifies a favourable outlook for the demonstration of an electrically driven laser. We find a significant trap density, whose cross-section for carrier capture is however low, yielding a minor impact on device performance
Two decades of successes and failures in controlling the transmission of HIV through injecting drug use in England and Wales, 1990 to 2011
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Imaging of SNR IC443 and W44 with the Sardinia Radio Telescope at 1.5 GHz and 7 GHz
Observations of supernova remnants (SNRs) are a powerful tool for
investigating the later stages of stellar evolution, the properties of the
ambient interstellar medium, and the physics of particle acceleration and
shocks. For a fraction of SNRs, multi-wavelength coverage from radio to ultra
high-energies has been provided, constraining their contributions to the
production of Galactic cosmic rays. Although radio emission is the most common
identifier of SNRs and a prime probe for refining models, high-resolution
images at frequencies above 5 GHz are surprisingly lacking, even for bright and
well-known SNRs such as IC443 and W44. In the frameworks of the Astronomical
Validation and Early Science Program with the 64-m single-dish Sardinia Radio
Telescope, we provided, for the first time, single-dish deep imaging at 7 GHz
of the IC443 and W44 complexes coupled with spatially-resolved spectra in the
1.5-7 GHz frequency range. Our images were obtained through on-the-fly mapping
techniques, providing antenna beam oversampling and resulting in accurate
continuum flux density measurements. The integrated flux densities associated
with IC443 are S_1.5GHz = 134 +/- 4 Jy and S_7GHz = 67 +/- 3 Jy. For W44, we
measured total flux densities of S_1.5GHz = 214 +/- 6 Jy and S_7GHz = 94 +/- 4
Jy. Spectral index maps provide evidence of a wide physical parameter scatter
among different SNR regions: a flat spectrum is observed from the brightest SNR
regions at the shock, while steeper spectral indices (up to 0.7) are observed
in fainter cooling regions, disentangling in this way different populations and
spectra of radio/gamma-ray-emitting electrons in these SNRs.Comment: 13 pages, 9 figures, accepted for publication to MNRAS on 18 May 201
Thermal issues for the optical transition radiation screen for the ELI-NP compton gamma source
A high brightness electron LINAC is being built in the Compton Gamma Source at the ELI Nuclear Physics facility in Romania. To achieve the design luminosity, a train of 32 bunches, 16 ns spaced, with a nominal charge of 250 pC will collide with a laser beam in two interaction points. Electron beam spot size is measured with Optical Transition Radiation (OTR) profile monitors. In order to measure the beam properties, the OTR screens must sustain the thermal and mechanical stress due to the energy deposited by bunches. This paper is an ANSYS study of the issues due to the high energy transferred to the OTR screens. Thermal multicycle analysis will be shown; each analysis will be followed by a structural analysis in order to investigate the performance of the materia
Investigating the high-frequency spectral features of SNRs Tycho, W44 and IC443 with the Sardinia Radio Telescope
The main characteristics in the radio continuum spectra of Supernova Remnants
(SNRs) result from simple synchrotron emission. In addition, electron
acceleration mechanisms can shape the spectra in specific ways, especially at
high radio frequencies. These features are connected to the age and the
peculiar conditions of the local interstellar medium interacting with the SNR.
Whereas the bulk radio emission is expected at up to GHz, sensitive
high-resolution images of SNRs above 10 GHz are lacking and are not easily
achievable, especially in the confused regions of the Galactic Plane. In the
framework of the early science observations with the Sardinia Radio Telescope
in February-March 2016, we obtained high-resolution images of SNRs Tycho, W44
and IC443 that provided accurate integrated flux density measurements at 21.4
GHz: 8.8 0.9 Jy for Tycho, 25 3 Jy for W44 and 66 7 Jy for
IC443. We coupled the SRT measurements with radio data available in the
literature in order to characterise the integrated and spatially-resolved
spectra of these SNRs, and to find significant frequency- and region-dependent
spectral slope variations. For the first time, we provide direct evidence of a
spectral break in the radio spectral energy distribution of W44 at an
exponential cutoff frequency of 15 2 GHz. This result constrains the
maximum energy of the accelerated electrons in the range GeV, in
agreement with predictions indirectly derived from AGILE and \textit{Fermi}-LAT
gamma-ray observations. With regard to IC443, our results confirm the
noticeable presence of a bump in the integrated spectrum around GHz
that could result from a spinning dust emission mechanism.Comment: 12 pages, 9 figure
Phase III studies on novel oral anticoagulants for stroke prevention in atrial fibrillation -a look beyond the excellent results
In this overview we address the three phase III studies that compared new oral anticoagulants (dabigatran, rivaroxaban and apixaban) with warfarin in the setting of stroke prevention in atrial fibrillation. Strengths and weaknesses of the studies were examined in detail through indirect comparison. We analyze and comment the inclusion and exclusion criteria, the characteristics of randomized patients, the primary efficacy and safety end points and side effects. All new oral anticoagulants resulted in being non-inferior to vitamin K antagonists in reducing stroke or systemic embolism in patients with atrial fibrillation. Dabigatran 150 mg and apixaban were superior to vitamin K antagonists. Importantly, new oral anticoagulants significantly reduced hemorrhagic stroke in all three studies. Major differences among new oral anticoagulants include the way they are eliminated and side effects. Both dabigatran and apixaban were tested in low- to moderate-risk patients (mean CHADS2 [Congestive heart failure, Hypertension, Age, Diabetes, Stroke] score = 2.1-2.2) whereas rivaroxaban was tested in high-risk patients (mean CHADS2 score = 3.48) and at variance with dabigatran and apixaban was administered once daily. Apixaban significantly reduced mortality from any cause. The choice of a new oral anticoagulant should take into account these and other differences between the new drugs
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