2,138 research outputs found
Evidence of a cyclotron feature in the spectrum of the anomalous X-ray pulsar 1RXS J170849-400910
We report the results of a long observation of the anomalous X-ray pulsar
1RXS J170849-400910 obtained with the BeppoSAX satellite in August 2001. The
best-fit phase-averaged spectrum was an absorbed power law plus blackbody
model, with photon index Gamma~2.4 and a blackbody temperature of kT_bb~0.4
keV. We confirm the presence of significant spectral variations with the
rotational phase of the pulsar. In the spectrum corresponding to the rising
part of the pulse we found an absorption-like feature at ~8.1 keV (a
significance of 4 sigma), most likely due to cyclotron resonant scattering. The
centroid energy converts to a magnetic field of 9x10^11 G and 1.6x10^15 G in
the case of electrons and protons, respectively. If confirmed, this would be
the first detection of a cyclotron feature in the spectrum of an anomalous
X-ray pulsar.Comment: 5 pages, 5 figures. Accepted for publication on ApJ Letter
XMM-Newton and Swift observations prove GRB 090709A to be a distant, standard, long GRB
GRB 090709A is a long gamma-ray burst (GRB) discovered by Swift, featuring a
bright X-ray afterglow as well as a faint infrared transient with very red and
peculiar colors. The burst attracted a large interest because of a possible
quasi-periodicity at P=8.1 s in the prompt emission, suggesting that it could
have a different origin with respect to standard, long GRBs. In order to
understand the nature of this burst, we obtained a target of opportunity
observation with XMM-Newton. X-ray spectroscopy, based on XMM-Newton and Swift
data, allowed us to model the significant excess in photoelectric absorption
with respect to the Galactic value as due to a large column density (about
6.5E+22 cm^-2) in the GRB host, located at z=4.2. Such a picture is also
consistent with the infrared transient's properties. Re-analysis of the prompt
emission, based on INTEGRAL and on Swift data, excludes any significant
modulation at P=8.1 s. Thus, we conclude that GRB 090709A is a distant,
standard, long GRB.Comment: 7 pages, 7 figures, 2 tables; MNRAS, in press. (V3: minor changes to
match the final version.
The 2008 October Swift detection of X-ray bursts/outburst from the transient SGR-like AXP 1E 1547.0-5408
We report on the detailed study of the 2008 October outburst from the
anomalous X-ray pulsar (AXP) 1E 1547.0-5408 discovered through the Swift/Burst
Alert Telescope (BAT) detection of SGR-like short X-ray bursts on 2008 October
3. The Swift/X-ray Telescope (XRT) started observing the source after less than
100 s since the BAT trigger, when the flux (about 6E-11 erg/cm^2/s in the 2-10
keV range) was >50 times higher than its quiescent level. Swift monitored the
outbursting activity of 1E 1547.0-5408 on a daily basis for approximately three
weeks. This strategy allowed us to find a phase-coherent solution for the
source pulsations after the burst, which, besides period and period derivative,
requires a positive Period second derivative term (spin-down increase). The
time evolution of the pulse shape is complex and variable, with the pulsed
fraction increasing from 20% to 50% within the Swift observational window. The
XRT spectra can be fitted well by means of a single component, either a
power-law (PL) or a blackbody (BB). During the very initial phases of the
outburst the spectrum is hard, with a PL photon index about 2 (or kT about 1.4
keV) which steepens to about 4 (or kT about 0.8 keV) within one day from the
BAT trigger, though the two components are likely present simultaneously during
the first day spectra. An INTEGRAL observation carried out five days after the
trigger provided an upper limit of about 2E-11 erg/cm^2/s to the emission of 1E
1547.0-5408 in the 18-60 keV band.Comment: 10 pages, 2 tables, 6 figures; accepted for publication in MNRA
The frontier of darkness: the cases of GRB 040223, GRB 040422, GRB 040624
Understanding the reasons for the faintness of the optical/near-infrared
afterglows of the so-called dark bursts is essential to assess whether they
form a subclass of GRBs, and hence for the use of GRBs in cosmology. With VLT
and other ground-based telescopes, we searched for the afterglows of the
INTEGRAL bursts GRB 040223, GRB 040422 and GRB 040624 in the first hours after
the triggers. A detection of a faint afterglow and of the host galaxy in the K
band was achieved for GRB 040422, while only upper limits were obtained for GRB
040223 and GRB 040624, although in the former case the X-ray afterglow was
observed. A comparison with the magnitudes of a sample of afterglows clearly
shows the faintness of these bursts, which are good examples of a population
that an increasing usage of large diameter telescopes is beginning to unveil.Comment: 4 pages, 2 figures. To appear in the proceedings of the 16th Annual
October Astrophysics Conference in Maryland "Gamma Ray Bursts in the Swift
Era", eds. S. Holt, N. Gehrels & J. Nouse
The T cell receptor repertoire of tumor infiltrating T cells is predictive and prognostic for cancer survival.
From Europe PMC via Jisc Publications RouterHistory: ppub 2021-07-01, epub 2021-07-02Publication status: PublishedFunder: Wellcome Trust; Grant(s): 100282/Z/12/ZFunder: Cancer Research UK; Grant(s): A22902, A27412Tumor infiltration by T cells is paramount for effective anti-cancer immune responses. We hypothesized that the T cell receptor (TCR) repertoire of tumor infiltrating T lymphocytes could therefore be indicative of the functional state of these cells and determine disease course at different stages in cancer progression. Here we show that the diversity of the TCR of tumor infiltrating T cell at baseline is prognostic in various cancers, whereas the TCR clonality of T cell infiltrating metastatic melanoma pre-treatment is predictive for activity and efficacy of PD1 blockade immunotherapy
The (un)resolved X-ray background in the Lockman Hole
Most of the soft and a growing fraction of the harder X-ray background has
been resolved into emission from point sources, yet the resolved fraction above
7 keV has only been poorly constrained. We use ~700 ks of XMM-Newton
observations of the Lockman Hole and a photometric approach to estimate the
total flux attributable to resolved sources in a number of different energy
bands. We find the resolved fraction of the X-ray background to be ~90 per cent
below 2 keV but it decreases rapidly at higher energies with the resolved
fraction above ~7 keV being only ~50 per cent. The integrated X-ray spectrum
from detected sources has a slope of Gamma~1.75, much softer than the Gamma=1.4
of the total background spectrum. The unresolved background component has the
spectral signature of highly obscured AGN.Comment: 6 pages, 6 figures, MNRAS Letters, in press, changed to reflect
accepted versio
HST/WFPC2 observations of the LMC pulsar PSR B0540-69
The study of the younger, and brighter, pulsars is important to understand
the optical emission properties of isolated neutron stars. PSRB0540-69, the
second brightest (V~22) optical pulsar, is obviously a very interesting target
for these investigations. The aim of this work is threefold: constraining the
pulsar proper motion and its velocity on the plane of the sky through optical
astrometry, obtaining a more precise characterisation of the pulsar optical
spectral energy distribution (SED) through a consistent set of multi-band,
high-resolution, imaging photometry observations, measuring the pulsar optical
phase-averaged linear polarisation, for which only a preliminary and uncertain
measurement was obtained so far from ground-based observations. We performed
high-resolution observations of PSRB0540-69 with the WFPC2 aboard the HST, in
both direct imaging and polarimetry modes. From multi-epoch astrometry we set a
3sigma upper limit of 1 mas/yr on the pulsar proper motion, implying a
transverse velocity <250 km/s at the 50 kpc LMC distance. Moreover, we
determined the pulsar absolute position with an unprecedented accuracy of 70
mas. From multi-band photometry we characterised the pulsar power-law spectrum
and we derived the most accurate measurement of the spectral index
(0.70+/-0.07) which indicates a spectral turnover between the optical and X-ray
bands. Finally, from polarimetry we obtained a new measurement of the pulsar
phase-averaged polarisation degree (16+/-4%),consistent with magnetosphere
models depending on the actual intrinsic polarisation degree and depolarisation
factor, and we found that the polarisation vector (22+/-12deg position angle)
is possibly aligned with the semi-major axis of the pulsar-wind nebula and with
the apparent proper motion direction of its bright emission knot.Comment: 14 pages, 12 figures, accepted for publication in Astronomy &
Astrophysic
Recommendations for improving the quality of reporting clinical electrochemotherapy studies based on qualitative systematic review
Background: Electrochemotherapy is becoming a well-established treatment for malignancies of skin and non-skin origin and its use is widening across Europe. The technique was developed and optimized from solid experimental and clinical evidence. A consensus document is now warranted to formalize reporting results, which should strengthen evidence-based practice recommendations. This consensus should be derived from high quality clinical data collection, clinical expertise and summarizing patient feedback. The first step, which is addressed in this paper, aims to critically analyze the quality of published studies and to provide the recommendations for reporting clinical trials on electrochemotherapy. Methods: The quality of reporting in published studies on electrochemotherapy was analyzed in order to produce procedure specific reporting recommendations. A comprehensive literature search of studies published from 2006 to 2015 was performed followed by qualitative analysis of manuscripts assessing for 47 quality criteria grouped into four major clusters: (1) trial design, (2) description of patient population, (3) description of treatment delivery and patient outcome, (4) analysis of results and their interpretation. The summary measure during literature assessment was the proportion of studies fulfilling each manuscript quality criteria. Results: A total of 56 studies were screened, from the period 2006 to 2015, of which 33 were included in the qualitative analysis, with a total of 1215 patients. Overall, the quality of reporting was highly variable. Twenty-four reports (73%) were single-center, non-comparative studies, and only 15 (45%) were prospective in nature (only 2 of them were entered into a clinical trials registry). Electrochemotherapy technique was consistently reported, with most studies (31/33) adhering closely to published standard operating procedures. The quality of reporting the patient population was variable among the analyzed studies, with only between 45% and 100% achieving dedicated quality criteria. Reporting of treatment delivery and patient outcome was also highly variable with studies only fulfilling between 3% and 100%. Finally, reporting study results critically varied, fulfilling from 27% to 100% of the quality criteria. Based on the critical issues emerging from this analysis, recommendations and minimal requirements for reporting clinical data on electrochemotherapy were prepared and summarized into a checklist. Conclusions: There is an increasing body of published clinical data on electrochemotherapy, but more high quality clinical data are needed. Published papers often lack accurate description of study population, treatment delivery as well as patient outcome. Our recommendations, provided in the form of a summary checklist, are intended to ameliorate data reporting in future studies on electrochemotherapy and help researchers to provide a solid evidence basis for clinical practice
A Supernova Candidate at z=0.092 in XMM-Newton Archival Data
During a search for X-ray transients in the XMM-Newton archive within the
EXTraS project, we discovered a new X-ray source that is detected only during a
~5 min interval of a ~21 h-long observation performed on 2011 June 21 (EXMM
023135.0-603743, probability of a random Poissonian fluctuation:
~). With dedicated follow-up observations, we found that its
position is consistent with a star-forming galaxy (SFR = 1-2
yr) at redshift ( Mpc). At this redshift,
the energy released during the transient event was erg in
the 0.3-10 keV energy band (in the source rest frame). The luminosity of the
transient, together with its spectral and timing properties, make EXMM
023135.0-603743 a gripping analog to the X-ray transient associated to SN
2008D, which was discovered during a Swift/XRT observation of the nearby
( Mpc) supernova-rich galaxy NGC 2770. We interpret the XMM-Newton event
as a supernova shock break-out or an early cocoon, and show that our
serendipitous discovery is compatible with the rate of core-collapse supernovae
derived from optical observations and much higher than that of tidal disruption
events.Comment: 11 pages, 6 figures; Revised version accepted for publication in The
Astrophysical Journa
A Project to Context Decarbonization Analysis (PCDA) to Select the Best Energy Transition Solution Fit for Funding
An Energy Transition (ET) solutions screening has been performed in a near-Europe (EU) geography (Central Asia) to assess the sustainability of investment opportunities on green technologies in line with Environmental, Social and Governance (ESG) criteria, EU climate ambition, market trends and Technology Readiness Level (TRL). Several configurations, namely a technological solution contextualized in its Life Cycle Assessment (LCA) perspective by the overall value chain, have been studied, analysed and compared through a Carbon Energy Environmental and Cost Model (CEE&C) in a Project to Context Decarbonization Analysis (PCDA). The outcome of this study allowed to select the best set of ET Solution fit for the Central Asia context and attractive for climate funding framework.
7 typical ET technologies with 3 to 6 different decarbonization scenarios for a total of 40+ configurations have been considered, ranked and tested against strategic stakeholders’ engagement criteria (industrial partner, state investments, feedstock provider, off-taker, financing institutions) and economic and financial criteria (project authorizations, feedstock guarantee, fiscal incentives, etc.). Key Performance Indicators (KPIs) considered for the ranking of configuration are Product Carbon Footprint (CTG), Greenhouse Gas (GHG) avoidance, Levelized Cost of Carbon (LCOC) by project Capital Expenditures (CAPEX) and LCOC by cost efficiency.
Our proposed paper intends to show how the results of the CEE&C model with the LCOC in a PCDA study can support stakeholders and investors to implement their geographical decarbonization ambition and strategy
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