113 research outputs found
The Efficacy of Fibrinogen Concentrates in Relation to Cryoprecipitate in Restoring Clot Integrity and Stability against Lysis
Funding: This work was supported in part by Tenovus Scotland Grampian (G17.03) and Friends of Anchor (SC025332). C.S.W. and N.J.M. were supported by the British Heart Foundation (PG/15/82/31721and PG/20/17/35050). Acknowledgments: We thank the NHS Grampian Haematology department for kindly performing the Clauss assay to measure the fibrinogen concentration in the cryoprecipitate. We thank the University of Aberdeen Microscopy and Histology facility for their advice and the use of their facilities. We thank Linda Robertson and Megan Simpson for their technical assistance.Peer reviewedPublisher PD
An Intraoperative Detecting Probe For Radio-Guided Surgery in Tumour Resection
The development of the based radio-guided surgery aims to extend
the technique to those tumours where surgery is the only possible treatment and
the assessment of the resection would most profit from the low background
around the lesion, as for brain tumours. Feasibility studies on meningioma,
glioma, and neuroendocrine tumors already estimated the potentiality of this
new treatment. To validate the technique, prototypes of the intraoperative
probe required by the technique to detect radiation have been
developed. This paper discusses the design details of the device and the tests
performed in laboratory. In such tests particular care has to be taken to
reproduce the surgical field conditions. The innovative technique to produce
specific phantoms and the dedicated testing protocols is described in detail.Comment: 7 pages, 15 figure
A novel role of CD4 Th17 cells in mediating cardiac allograft rejection and vasculopathy
T-bet plays a crucial role in Th1 development. We investigated the role of T-bet in the development of allograft rejection in an established MHC class IIâmismatched (bm12 into B6) model of chronic allograft vasculopathy (CAV). Intriguingly, and in contrast to IFN-Îłâ/â mice that are protected from CAV, T-betâ/â recipients develop markedly accelerated allograft rejection accompanied by early severe vascular inflammation and vasculopathy, and infiltration by predominantly IL-17âproducing CD4 T cells. Concurrently, T-betâ/â mice exhibit a T helper type 1 (Th1)âdeficient environment characterized by profound IFN-Îł deficiency, a Th2 switch characterized by increased production of interleukin (IL) 4, IL-5, IL-10, and IL-13 cytokines, as well as increased production of the proinflammatory cytokines IL-6, IL-12p40, and IL-17. Neutralization of IL-17 inhibits accelerated allograft rejection and vasculopathy in T-betâ/â mice. Interestingly, CD4 but not CD8 T cell deficiency in T-betâ/â mice affords dramatic protection from vasculopathy and facilitates long-term graft acceptance. This is the first study establishing that in the absence of Th1-mediated alloimmune responses, CD4 Th17 cells mediate an aggressive proinflammatory response culminating in severe accelerated allograft rejection and vasculopathy. These results have important implications for the development of novel therapies to target this intractable problem in clinical solid organ transplantation
GRB 070724B: the first gamma ray burst localized by SuperAGILE and its Swift X-ray afterglow
GRB 070724B is the first gamma ray burst localized by SuperAGILE, the hard X-ray monitor aboard the AGILE satellite. The coordinates of the event were published similar to 19 h after the trigger. The Swift X-Ray Telescope pointed at the SuperAGILE location and detected the X-ray afterglow inside the SuperAGILE error circle. The AGILE gamma-ray Tracker and Minicalorimeter did not detect any significant gamma ray emission associated with GRB 070724B in the MeV and GeV range, neither prompt nor delayed. Searches for the optical afterglow were performed by the Swift UVOT and the Palomar automated 60-inch telescopes, resulting in no significant detection. Similarly, the Very Large Array did not detect any radio afterglow. This is the first GRB event associated with an X-ray afterglow with a firm upper limit in the 100 MeV-30 GeV energy range
X-ray polarimetry reveals the magnetic field topology on sub-parsec scales in Tycho's supernova remnant
Supernova remnants are commonly considered to produce most of the Galactic
cosmic rays via diffusive shock acceleration. However, many questions about the
physical conditions at shock fronts, such as the magnetic-field morphology
close to the particle acceleration sites, remain open. Here we report the
detection of a localized polarization signal from some synchrotron X-ray
emitting regions of Tycho's supernova remnant made by the Imaging X-ray
Polarimetry Explorer. The derived polarization degree of the X-ray synchrotron
emission is 9+/-2% averaged over the whole remnant, and 12+/-2% at the rim,
higher than the 7-8% polarization value observed in the radio band. In the west
region the polarization degree is 23+/-4%. The X-ray polarization degree in
Tycho is higher than for Cassiopeia A, suggesting a more ordered magnetic-field
or a larger maximum turbulence scale. The measured tangential polarization
direction corresponds to a radial magnetic field, and is consistent with that
observed in the radio band. These results are compatible with the expectation
of turbulence produced by an anisotropic cascade of a radial magnetic-field
near the shock, where we derive a magnetic-field amplification factor of
3.4+/-0.3. The fact that this value is significantly smaller than those
expected from acceleration models is indicative of highly anisotropic
magnetic-field turbulence, or that the emitting electrons either favor regions
of lower turbulence, or accumulate close to where the magnetic-field
orientation is preferentially radially oriented due to hydrodynamical
instabilities.Comment: 31 pages, 7 figures, 3 tables. Accepted for publication in ApJ.
Revised versio
IXPE and XMM-Newton observations of the Soft Gamma Repeater SGR 1806-20
Recent observations with the Imaging X-ray Polarimetry Explorer (IXPE) of two
anomalous X-ray pulsars provided evidence that X-ray emission from magnetar
sources is strongly polarized. Here we report on the joint IXPE and XMM-Newton
observations of the soft {\gamma}-repeater SGR 1806-20. The spectral and timing
properties of SGR 1806-20 derived from XMM-Newton data are in broad agreement
with previous measurements; however, we found the source at an all-time-low
persistent flux level. No significant polarization was measured apart from the
4-5 keV energy range, where a probable detection with PD=31.6\pm 10.5% and
PA=-17.6\pm 15 deg was obtained. The resulting polarization signal, together
with the upper limits we derive at lower and higher energies 2-4 and 5-8 keV,
respectively) is compatible with a picture in which thermal radiation from the
condensed star surface is reprocessed by resonant Compton scattering in the
magnetosphere, similar to what proposed for the bright magnetar 4U 0142+61.Comment: 11 pages, 3 figures, accepted for publication in Ap
The AGILE Mission
AGILE is an Italian Space Agency mission dedicated to observing the gamma-ray Universe. The AGILE's very innovative instrumentation for the first time combines a gamma-ray imager (sensitive in the energy range 30 MeV-50 GeV), a hard X-ray imager (sensitive in the range 18-60 keV), a calorimeter (sensitive in the range 350 keV-100 MeV), and an anticoincidence system. AGILE was successfully launched on 2007 April 23 from the Indian base of Sriharikota and was inserted in an equatorial orbit with very low particle background. Aims. AGILE provides crucial data for the study of active galactic nuclei, gamma-ray bursts, pulsars, unidentified gamma-ray sources, galactic compact objects, supernova remnants, TeV sources, and fundamental physics by microsecond timing. Methods. An optimal sky angular positioning (reaching 0.1 degrees in gamma- rays and 1-2 arcmin in hard X-rays) and very large fields of view (2.5 sr and 1 sr, respectively) are obtained by the use of Silicon detectors integrated in a very compact instrument. Results. AGILE surveyed the gamma- ray sky and detected many Galactic and extragalactic sources during the first months of observations. Particular emphasis is given to multifrequency observation programs of extragalactic and galactic objects. Conclusions. AGILE is a successful high-energy gamma-ray mission that reached its nominal scientific performance. The AGILE Cycle-1 pointing program started on 2007 December 1, and is open to the international community through a Guest Observer Program
Magnetic structures and turbulence in SN 1006 revealed with imaging X-ray polarimetry
Young supernova remnants (SNRs) strongly modify surrounding magnetic fields,
which in turn play an essential role in accelerating cosmic rays (CRs). X-ray
polarization measurements probe magnetic field morphology and turbulence at the
immediate acceleration site. We report the X-ray polarization distribution in
the northeastern shell of SN1006 from a 1 Ms observation with the Imaging X-ray
Polarimetry Explorer (IXPE). We found an average polarization degree of
and an average polarization angle of
(measured on the plane of the sky from north to east). The X-ray polarization
angle distribution reveals that the magnetic fields immediately behind the
shock in the northeastern shell of SN 1006 are nearly parallel to the shock
normal or radially distributed, similar to that in the radio observations, and
consistent with the quasi-parallel CR acceleration scenario. The X-ray emission
is marginally more polarized than that in the radio band. The X-ray
polarization degree of SN 1006 is much larger than that in Cas A and Tycho,
together with the relatively tenuous and smooth ambient medium of the remnant,
favoring that CR-induced instabilities set the turbulence in SN 1006 and CR
acceleration is environment-dependent.Comment: 15 pages, 4 Figures, 2 Tables; accepted for publication in The
Astrophysical Journa
X-ray pulsar GRO J100857 as an orthogonal rotator
X-ray polarimetry is a unique way to probe geometrical configuration of
highly-magnetized accreting neutron stars (X-ray pulsars). GRO J100857 is
the first transient X-ray pulsar observed at two different flux levels by the
Imaging X-ray Polarimetry Explorer (IXPE) during its outburst in November 2022.
The polarization properties were found to be independent of the source
luminosity, with the polarization degree varying between non-detection to about
15% over the pulse phase. Fitting the phase-resolved spectro-polarimetric data
with the rotating vector model allowed us to estimate the pulsar inclination
(130 deg, which is in good agreement with the orbital inclination), the
position angle (75 deg) of the pulsar spin axis, and the magnetic obliquity (74
deg). This makes GRO J100857 the first confidently identified X-ray pulsar
as a nearly orthogonal rotator. The results are discussed in the context of the
neutron star atmosphere models and theories of pulsars' axis alignment.Comment: 11 pages, 7 figures, submitted to A&A. arXiv admin note: text overlap
with arXiv:2209.0244
The Polarized Cosmic Hand: IXPE Observations of PSR B1509-58/MSH 15-52
We describe IXPE polarization observations of the Pulsar Wind Nebula (PWN)
MSH15-52, the `Cosmic Hand'. We find X-ray polarization across the PWN, with B
field vectors generally aligned with filamentary X-ray structures. High
significance polarization is seen in arcs surrounding the pulsar and toward the
end of the `jet', with polarization degree PD>70%, thus approaching the maximum
allowed synchrotron value. In contrast, the base of the jet has lower
polarization, indicating a complex magnetic field at significant angle to the
jet axis. We also detect significant polarization from PSR B1509-58 itself.
Although only the central pulse-phase bin of the pulse has high individual
significance, flanking bins provide lower significance detections and, in
conjunction with the X-ray image and radio polarization, can be used to
constrain rotating vector model solutions for the pulsar geometry.Comment: To appear in the Astrophysical Journa
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