973 research outputs found
Discovery of the Very Red Near-Infrared and Optical Afterglow of the Short-Duration GRB 070724A
[Abridged] We report the discovery of the near-infrared and optical afterglow
of the short-duration gamma-ray burst GRB070724A. The afterglow is detected in
i,J,H,K observations starting 2.3 hr after the burst with K=19.59+/-0.16 mag
and i=23.79+/-0.07 mag, but is absent in images obtained 1.3 years later.
Fading is also detected in the K-band between 2.8 and 3.7 hr at a 4-sigma
significance level. The optical/near-IR spectral index, beta_{O,NIR}=-2, is
much redder than expected in the standard afterglow model, pointing to either
significant dust extinction, A_{V,host}~2 mag, or a non-afterglow origin for
the near-IR emission. The case for extinction is supported by a shallow optical
to X-ray spectral index, consistent with the definition for ``dark bursts'',
and a normal near-IR to X-ray spectral index. Moreover, a comparison to the
optical discovery magnitudes of all short GRBs with optical afterglows
indicates that the near-IR counterpart of GRB070724A is one of the brightest to
date, while its observed optical emission is one of the faintest. In the
context of a non-afterglow origin, the near-IR emission may be dominated by a
mini-supernova, leading to an estimated ejected mass of M~10^-4 Msun and a
radioactive energy release efficiency of f~0.005 (for v~0.3c). However, the
mini-SN model predicts a spectral peak in the UV rather than near-IR,
suggesting that this is either not the correct interpretation or that the
mini-SN models need to be revised. Finally, the afterglow coincides with a star
forming galaxy at z=0.457, previously identified as the host based on its
coincidence with the X-ray afterglow position (~2" radius). Our discovery of
the optical/near-IR afterglow makes this association secure.Comment: Submitted to ApJ; 10 pages, 5 figures, 1 tabl
Prevalence of Dementia in Older Adults in Central and Eastern Europe: A Systematic Review and Meta-Analysis
Data on dementia prevalence in Europe are primarily based on studies from Western Europe. Central and Eastern European countries differ from Western European countries in their average income and other socioeconomic and health factors that are relevant for dementia risk. We, therefore, conducted a systematic review of population-based studies on prevalence of dementia in Central and Eastern Europe. We searched in electronic databases from the date of inception up to July 2019, updated in October 2020. We hand-searched references of included articles and contacted experts in each country to identify further articles. We combined studies by meta-analysis where possible. Ten population-based studies (n = 30,268) met inclusion criteria. We meta-analysed seven studies (n = 11,994). The selected studies were conducted across 5 countries with no studies identified for the vast majority of countries in this region. Prevalence of all-cause dementia was 6.7% (95% CI 5.1–8.2) in those aged 60 or over, and 7.1% (95% CI 5.1–9.2) in those aged 65 and over. Prevalence rates were similar to those in Western Europe, but are increasing over time, compared with the patterns of reduction in age-specific prevalence in Western Europe
Swift J1112.2-8238: A Candidate Relativistic Tidal Disruption Flare
We present observations of Swift J1112.2-8238, and identify it as a candidate
relativistic tidal disruption flare (rTDF). The outburst was first detected by
Swift/BAT in June 2011 as an unknown, long-lived (order of days) -ray
transient source. We show that its position is consistent with the nucleus of a
faint galaxy for which we establish a likely redshift of based on a
single emission line that we interpret as the blended [OII]
doublet. At this redshift, the peak X/-ray luminosity exceeded
ergs s, while a spatially coincident optical transient source
had (M at ) during early
observations, days after the Swift trigger. These properties place
Swift J1112.2-8238 in a very similar region of parameter space to the two
previously identified members of this class, Swift J1644+57 and Swift
J2058+0516. As with those events the high-energy emission shows evidence for
variability over the first few days, while late time observations, almost 3
years post-outburst, demonstrate that it has now switched off. Swift
J1112.2-8238 brings the total number of such events observed by Swift to three,
interestingly all detected by Swift over a 3 month period ( of its
total lifetime as of March 2015). While this suggests the possibility that
further examples may be uncovered by detailed searches of the BAT archives, the
lack of any prime candidates in the years since 2011 means these events are
undoubtedly rare.Comment: 11 pages, 5 figures, accepted for publication by MNRA
Contemporary roles of registries in clinical cardiology: Insights from Western and Eastern European countries
Despite substantial advances in the management of cardiovascular disease, it remains a major cause of morbidity and mortality worldwide. Globally, cardiovascular disease is expected to account for over 23 million deaths by the year 2030, mostly attributable to an increasing incidence in low and middle income countries. Within the World Health Organisation European Region, cardiovascular disease accounts for over 4 million deaths per year. However, this rate varies considerably between European countries with evidence from observational databases to suggest that mortality rates from cardiovascular disease are higher in countries of Central and Eastern Europe, Central Asia, Finland and Malta
A Beaming-Independent Estimate of the Energy Distribution of Long Gamma-Ray Bursts: Initial Results and Future Prospects
We present single-epoch radio afterglow observations of 24 long-duration
gamma-ray burst (GRB) on a timescale of >100 d after the burst. These
observations trace the afterglow evolution when the blastwave has decelerated
to mildly- or non-relativistic velocities and has roughly isotropized. We infer
beaming-independent kinetic energies using the Sedov-Taylor self-similar
solution, and find a median value for the sample of detected bursts of about
7x10^51 erg, with a 90% confidence range of 1.1x10^50-3.3x10^53 erg. Both the
median and 90% confidence range are somewhat larger than the results of
multi-wavelength, multi-epoch afterglow modeling (including large beaming
corrections), and the distribution of beaming-corrected gamma-ray energies.
This is due to bursts in our sample with only a single-frequency observation
for which we can only determine an upper bound on the peak of the synchrotron
spectrum. This limitation leads to a wider range of allowed energies than for
bursts with a well-measured spectral peak. Our study indicates that
single-epoch centimeter-band observations covering the spectral peak on a
timescale of ~1 yr can provide a robust estimate of the total kinetic energy
distribution with a small investment of telescope time. The substantial
increase in bandwidth of the EVLA (up to 8 GHz simultaneously with full
coverage at 1-40 GHz) will provide the opportunity to estimate the kinetic
energy distribution of GRBs with only a few hours of data per burst.Comment: Submitted to ApJ; 11 pages, 5 figures, 2 table
A year in the life of GW170817: the rise and fall of a structured jet from a binary neutron star merger
We present the results of our year-long afterglow monitoring of GW170817, the
first binary neutron star (NS) merger detected by advanced LIGO and advanced
Virgo. New observations with the Australian Telescope Compact Array (ATCA) and
the Chandra X-ray Telescope were used to constrain its late-time behavior. The
broadband emission, from radio to X-rays, is well-described by a simple
power-law spectrum with index ~0.585 at all epochs. After an initial shallow
rise ~t^0.9, the afterglow displayed a smooth turn-over, reaching a peak X-ray
luminosity of ~5e39 erg/s at 160 d, and has now entered a phase of rapid
decline ~t^(-2). The latest temporal trend challenges most models of choked
jet/cocoon systems, and is instead consistent with the emergence of a
relativistic structured jet seen at an angle of ~22 deg from its axis. Within
such model, the properties of the explosion (such as its blastwave energy
E_K~2E50 erg, jet width theta_c~4 deg, and ambient density n~3E-3 cm^(-3)) fit
well within the range of properties of cosmological short GRBs.Comment: 11 pages, 8 figures, 2 tables, MNRAS, in press. Final version, minor
changes only relative to original submission dated 21 August 201
The Role of Vasospasm and Microcirculatory Dysfunction in Fluoropyrimidine-Induced Ischemic Heart Disease
Cardiovascular diseases and cancer are the leading cause of morbidity and mortality globally. Cardiotoxicity from chemotherapeutic agents results in substantial morbidity and mortality in cancer survivors and patients with active cancer. Cardiotoxicity induced by 5-fluorouracil (5-FU) has been well established, yet its incidence, mechanisms, and manifestation remain poorly defined. Ischemia secondary to coronary artery vasospasm is thought to be the most frequent cardiotoxic effect of 5-FU. The available evidence of 5-FU-induced epicardial coronary artery spasm and coronary microvascular dysfunction suggests that endothelial dysfunction or primary vascular smooth muscle dysfunction (an endothelial-independent mechanism) are the possible contributing factors to this form of cardiotoxicity. In patients with 5-FU-related coronary artery vasospasm, termination of chemotherapy and administration of nitrates or calcium channel blockers may improve ischemic symptoms. However, there are variable results after administration of nitrates or calcium channel blockers in patients treated with 5-FU presumed to have myocardial ischemia, suggesting mechanisms other than impaired vasodilatory response. Clinicians should investigate whether chest pain and ECG changes can reasonably be attributed to 5-FU-induced cardiotoxicity. More prospective data and clinical randomized trials are required to understand and mitigate potentially adverse outcomes from 5-FU-induced cardiotoxicity
Constraining the Progenitor Companion of the Nearby Type Ia SN 2011fe with a Nebular Spectrum at +981 Days
We present an optical nebular spectrum of the nearby Type Ia supernova
2011fe, obtained 981 days after explosion. SN 2011fe exhibits little evolution
since the +593 day optical spectrum, but there are several curious aspects in
this new extremely late-time regime. We suggest that the persistence of the
~\AA\ feature is due to Na I D, and that a new emission feature at
~\AA\ may be [Ca II]. Also, we discuss whether the new emission
feature at ~\AA\ might be [Fe I] or the high-velocity hydrogen
predicted by Mazzali et al. The nebular feature at 5200~\AA\ exhibits a linear
velocity evolution of per 100 days from at least
+220 to +980 days, but the line's shape also changes in this time, suggesting
that line blending contributes to the evolution. At days after
explosion, flux from the SN has declined to a point where contribution from a
luminous secondary could be detected. In this work we make the first
observational tests for a post-impact remnant star and constrain its
temperature and luminosity to and
. Additionally, we do not see any evidence for narrow H
emission in our spectrum. We conclude that observations continue to strongly
exclude many single-degenerate scenarios for SN 2011fe.Comment: 11 pages, 10 figures, published by MNRA
Far-Ultraviolet to Near-Infrared Spectroscopy of A Nearby Hydrogen Poor Superluminous Supernova Gaia16apd
We report the first maximum-light far-Ultraviolet to near-infrared spectra
(1000A - 1.62um, rest) of a H-poor superluminous supernova, Gaia16apd. At
z=0.1018, it is one of the closest and the UV brightest such events, with 17.4
(AB) magnitude in Swift UV band (1928A) at -11days pre-maximum. Assuming an
exponential form, we derived the rise time of 33days and the peak bolometric
luminosity of 3x10^{44}ergs^-1. At maximum light, the estimated photospheric
temperature and velocity are 17,000K and 14,000kms^-1 respectively. The
inferred radiative and kinetic energy are roughly 1x10^{51} and 2x10^{52}erg.
Gaia16apd is extremely UV luminous, emitting 50% of its total luminosity at
1000 - 2500A. Compared to the UV spectra (normalized at 3100A) of well studied
SN1992A (Ia), SN2011fe(Ia), SN1999em (IIP) and SN1993J (IIb), it has orders of
magnitude more far-UV emission. This excess is interpreted primarily as a
result of weaker metal line blanketing due to much lower abundance of
iron-group elements in the outer ejecta. Because these elements originate
either from the natal metallicity of the star, or have been newly produced, our
observation provides direct evidence that little of these freshly synthesized
material, including 56Ni, was mixed into the outer ejecta, and the progenitor
metallicity is likely sub-solar. This disfavors Pair-Instability Supernova
(PISN) models with Helium core masses >=90Msun, where substantial 56Ni material
is produced. Higher photospheric temperature of Gaia16apd than that of normal
SNe may also contribute to the observed far-UV excess. We find some indication
that UV luminous SLSNe-I like Gaia16apd could be common. Using the UV spectra,
we show that WFIRST could detect SLSNe-I out to redshift of 8.Comment: 19 pages. Match with the version accepted in Ap
Late-Time Spectral Observations of the Strongly Interacting Type Ia Supernova PTF11kx
PTF11kx was a Type Ia supernova (SN Ia) that showed time-variable absorption
features, including saturated Ca II H&K lines that weakened and eventually went
into emission. The strength of the emission component of H{\alpha} increased,
implying that the SN was undergoing significant interaction with its
circumstellar medium (CSM). These features were blueshifted slightly and showed
a P-Cygni profile, likely indicating that the CSM was directly related to, and
probably previously ejected by, the progenitor system itself. These and other
observations led Dilday et al. (2012) to conclude that PTF11kx came from a
symbiotic nova progenitor like RS Oph. In this work we extend the spectral
coverage of PTF11kx to 124-680 rest-frame days past maximum brightness. These
spectra of PTF11kx are dominated by H{\alpha} emission (with widths of ~2000
km/s), strong Ca II emission features (~10,000 km/s wide), and a blue
"quasi-continuum" due to many overlapping narrow lines of Fe II. Emission from
oxygen, He I, and Balmer lines higher than H{\alpha} is weak or completely
absent at all epochs, leading to large observed H{\alpha}/H{\beta} intensity
ratios. The broader (~2000 km/s) H{\alpha} emission appears to increase in
strength with time for ~1 yr, but it subsequently decreases significantly along
with the Ca II emission. Our latest spectrum also indicates the possibility of
newly formed dust in the system as evidenced by a slight decrease in the red
wing of H{\alpha}. During the same epochs, multiple narrow emission features
from the CSM temporally vary in strength. The weakening of the H{\alpha} and Ca
II emission at late times is possible evidence that the SN ejecta have
overtaken the majority of the CSM and agrees with models of other strongly
interacting SNe Ia. The varying narrow emission features, on the other hand,
may indicate that the CSM is clumpy or consists of multiple thin shells.Comment: 12 pages, 7 figures, 1 table, re-submitted to Ap
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