7,880 research outputs found
Swift observations of GRB 060614: an anomalous burst with a well behaved afterglow
GRB 060614 is a remarkable GRB observed by Swift with puzzling properties,
which challenge current progenitor models. The lack of any bright SN down to
very strict limits and the vanishing spectral lags are typical of short GRBs,
strikingly at odds with the long (102s) duration of this event. Here we present
spectral and temporal analysis of the Swift observations. We show that the
burst presents standard optical, UV and X-ray afterglows. An achromatic break
is observed simultaneously in optical and X-rays, at a time consistent with the
break in the R-band light curve measured by the VLT. The achromatic behaviour
and the consistent post-break decay slopes make GRB 060614 one of the best
examples of a jet break for a Swift burst. The optical, UV and X-rays afterglow
light curves have also an earlier break at ~30 ks. In the optical, there is
strong spectral evolution around this break, suggesting the passage of a break
frequency through the optical/UV band. The very blue spectrum at early times
and the trend in the light curves (rising at low frequencies, and decaying at
higher energies) suggest this may be the injection frequency. The early X-ray
light curve is well interpreted as the X-ray counterpart of the burst extended
emission. Spectral analysis of BAT/XRT data in the 80s overlap time show that
the Ep of the burst has decreased to as low as 8keV at the beginning of the XRT
observation. The Ep continues to decrease through the XRT energy band and exits
it at about 500s after the trigger. The average Ep of the burst is likely < 24
keV but larger than 8 keV. The initial peak observed by BAT is however
distinctly harder than the rest with Ep ~300 keV as measured by Konus Wind.
Considering the time-averaged spectral properties, GRB 060614 is consistent
with the Eiso-Ep_rest, Egamma-Ep_rest, and Liso-Ep correlations.Comment: 20 pages, 9 figures, 8 tables. Abstract shortened for posting on
astro-ph. Accepted for publication by A&
The diagnostic value of pleural fluid homocysteine in malignant pleural effusion
Background
Pleural fluid homocysteine (HCY) can be useful for diagnosis of malignant pleural effusion (MPE). There are no published studies comparing the diagnostic accuracy of HCY with other tumour markers in pleural fluid for diagnosis of MPE. The aim was to compare the accuracy of HCY with that of carcinoembryonic antigen (CEA), cancer antigen (CA) 15.3, CA19.9 and CA125 in pleural fluid and to develop a probabilistic model using these biomarkers to differentiate benign (BPE) from MPE.
Methods
Patients with pleural effusion were randomly included. HCY, CEA, CA15.3, CEA19.9 and CA125 were quantified in pleural fluid. Patients were classified into two groups: MPE or BPE. By applying logistic regression analysis, a multivariate probabilistic model was developed using pleural fluid biomarkers. The diagnostic accuracy was determined by receiver operating characteristic (ROC) curves and calculating the area under the curve (AUC).
Results
Population of study comprised 133 patients (72 males and 61 females) aged between 1 and 96 years (median = 70 years), 81 BPE and 52 MPE. The logistic regression analysis included HCY (p< 0.0001) and CEA (p = 0.0022) in the probabilistic model and excluded the other tumour markers. The probabilistic model was: HCY+CEA = Probability(%) = 100x( 1 +e(-z))(-1), where Z = 0.5471x[ HCY]+0.3846x[ CEA]-8.2671. The AUCs were 0.606, 0.703, 0.778, 0.800, 0.846 and 0.948 for CA125, CA19.9, CEA, CA15.3, HCY and HCY+CEA, respectively.
Conclusions
Pleural fluid HCY has higher accuracy for diagnosis of MPE than CEA, CA15.3, CA19.9 and CA125. The combination of HCY and CEA concentrations in pleural fluid significantly improves the diagnostic accuracy of the test
Discovery of a Supernova Explosion at Half the Age of the Universe and its Cosmological Implications
The ultimate fate of the universe, infinite expansion or a big crunch, can be
determined by measuring the redshifts, apparent brightnesses, and intrinsic
luminosities of very distant supernovae. Recent developments have provided
tools that make such a program practicable: (1) Studies of relatively nearby
Type Ia supernovae (SNe Ia) have shown that their intrinsic luminosities can be
accurately determined; (2) New research techniques have made it possible to
schedule the discovery and follow-up observations of distant supernovae,
producing well over 50 very distant (z = 0.3 -- 0.7) SNe Ia to date. These
distant supernovae provide a record of changes in the expansion rate over the
past several billion years. By making precise measurements of supernovae at
still greater distances, and thus extending this expansion history back far
enough in time, we can distinguish the slowing caused by the gravitational
attraction of the universe's mass density Omega_M from the effect of a possibly
inflationary pressure caused by a cosmological constant Lambda. We report here
the first such measurements, with our discovery of a Type Ia supernova (SN
1997ap) at z = 0.83. Measurements at the Keck II 10-m telescope make this the
most distant spectroscopically confirmed supernova. Over two months of
photometry of SN 1997ap with the Hubble Space Telescope and ground-based
telescopes, when combined with previous measurements of nearer SNe Ia, suggests
that we may live in a low mass-density universe. Further supernovae at
comparable distances are currently scheduled for ground and space-based
observations.Comment: 12 pages and 4 figures (figure 4 is repeated in color and black and
white) Nature, scheduled for publication in the 1 January, 1998 issue. Also
available at http://www-supernova.lbl.go
The impact of the COVID-19 pandemic upon pancreatic cancer treatment (CONTACT Study): a UK national observational cohort study.
INTRODUCTION: CONTACT is a national multidisciplinary study assessing the impact of the COVID-19 pandemic upon diagnostic and treatment pathways among patients with pancreatic ductal adenocarcinoma (PDAC). METHODS: The treatment of consecutive patients with newly diagnosed PDAC from a pre-COVID-19 pandemic cohort (07/01/2019-03/03/2019) were compared to a cohort diagnosed during the first wave of the UK pandemic ('COVID' cohort, 16/03/2020-10/05/2020), with 12-month follow-up. RESULTS: Among 984 patients (pre-COVID: nâ=â483, COVID: nâ=â501), the COVID cohort was less likely to receive staging investigations other than CT scanning (29.5% vs. 37.2%, pâ=â0.010). Among patients treated with curative intent, there was a reduction in the proportion of patients recommended surgery (54.5% vs. 76.6%, pâ=â0.001) and increase in the proportion recommended upfront chemotherapy (45.5% vs. 23.4%, pâ=â0.002). Among patients on a non-curative pathway, fewer patients were recommended (47.4% vs. 57.3%, pâ=â0.004) or received palliative anti-cancer therapy (20.5% vs. 26.5%, pâ=â0.045). Ultimately, fewer patients in the COVID cohort underwent surgical resection (6.4% vs. 9.3%, pâ=â0.036), whilst more patients received no anti-cancer treatment (69.3% vs. 59.2% pâ=â0.009). Despite these differences, there was no difference in median overall survival between the COVID and pre-COVID cohorts, (3.5 (IQR 2.8-4.1) vs. 4.4 (IQR 3.6-5.2) months, pâ=â0.093). CONCLUSION: Pathways for patients with PDAC were significantly disrupted during the first wave of the COVID-19 pandemic, with fewer patients receiving standard treatments. However, no significant impact on survival was discerned
Identification and characterization of Rhipicephalus (Boophilus) microplus candidate protective antigens for the control of cattle tick infestations
The cattle ticks, Rhipicephalus (Boophilus) spp., affect cattle production in tropical and subtropical regions of the world. Tick vaccines constitute a cost-effective and environmentally friendly alternative to tick control. The recombinant Rhipicephalus microplus Bm86 antigen has been shown to protect cattle against tick infestations. However, variable efficacy of Bm86-based vaccines against geographic tick strains has encouraged the research for additional tick-protective antigens. Herein, we describe the analysis of R. microplus glutathione-S transferase, ubiquitin (UBQ), selenoprotein W, elongation factor-1 alpha, and subolesin (SUB) complementary DNAs (cDNAs) by RNA interference (RNAi) in R. microplus and Rhipicephalus annulatus. Candidate protective antigens were selected for vaccination experiments based on the effect of gene knockdown on tick mortality, feeding, and fertility. Two cDNA clones encoding for UBQ and SUB were used for cattle vaccination and infestation with R. microplus and R. annulatus. Control groups were immunized with recombinant Bm86 or adjuvant/saline. The highest vaccine efficacy for the control of tick infestations was obtained for Bm86. Although with low immunogenic response, the results with the SUB vaccine encourage further investigations on the use of recombinant subolesin alone or in combination with other antigens for the control of cattle tick infestations. The UBQ peptide showed low immunogenicity, and the results of the vaccination trial were inconclusive to assess the protective efficacy of this antigen. These experiments showed that RNAi could be used for the selection of candidate tick-protective antigens. However, vaccination trials are necessary to evaluate the effect of recombinant antigens in the control of tick infestations, a process that requires efficient recombinant protein production and formulation systems
Structure and Stability of an Amorphous Metal
Using molecular dynamics simulations, with a realistic many-body
embedded-atom potential, and a novel method to characterize local order, we
study the structure of pure nickel during the rapid quench of the liquid and in
the resulting glass. In contrast with previous simulations with pair
potentials, we find more crystalline order and fewer icosahedra for slower
quenching rates, resulting in a glass less stable against crystallization. It
is shown that there is not a specific amorphous structure, only the arrest of
the transition from liquid to crystal, resulting in small crystalline clusters
immersed in an amorphous matrix with the same structure of the liquid.Comment: 4 pages, 4 ps figs., to appear in Phys. Rev. Let
Guidance on Noncorticosteroid Systemic Immunomodulatory Therapy in Noninfectious Uveitis : Fundamentals Of Care for UveitiS (FOCUS) Initiative
Supplemental material available at www.aaojournal.org. Supported by AbbVie, Inc., and the Fundamentals of Care for Uveitis Initiative National Faculty. This manuscript was developed subsequent to an AbbVie-sponsored literature review of noninfectious, nonanterior uveitis. The meeting was conducted to understand the available literature regarding the management of patients with noninfectious, nonanterior uveitis. The program involved a total of 139 experts from 28 countries, who were selected for participation by AbbVie. However, AbbVie was not involved in the development of the manuscript. The authors maintained complete control over the content and this manuscript reflects the opinions of the authors. AbbVie selected the discussion participants and reviewed the final manuscript draft for scientific accuracy, but the authors determined the final content. All authors made substantial contributions to the article or critically revised it for important intellectual content and approved the final manuscript. AbbVie provided funding to invited participants, including honoraria for their attendance at the meetings. Travel to and from the meetings was reimbursed. No payments were made to the authors for the development of this manuscript. Dhinakaran Sambandan, PhD, and Shula Sarner, PhD, of Lucid Partners, Burleighfield House, Buckinghamshire, United Kingdom, provided medical writing and editorial support to the authors in the development of this manuscript; financial support for these services was provided by AbbVie. AbbVie reviewed the manuscript, but was not involved in the methodology, data collection and analysis, or completion of this manuscript.Peer reviewedPublisher PD
The updated spectral catalogue of INTEGRAL Gamma-Ray Bursts
We present a catalogue with the properties of all the bursts detected and
localized by the IBIS instrument onboard the INTEGRAL satellite from November
2002 to September 2008. The sample is composed of 56 bursts, corresponding to a
rate of ~ 0.8 GRB per month. Thanks to the performances of the INTEGRAL Burst
Alert System, 50% of the IBIS GRBs have detected afterglows, while 5% have
redshift measurements. A spectral analysis of the 43 bursts in the INTEGRAL
public archive has been carried out using the most recent software and
calibration, deriving an updated, homogeneous and accurate catalogue with the
spectral features of the sample. When possible also a time-resolved spectral
analysis has been carried out. The GRBs in the sample have 20-200 keV fluences
in the range 5 x 1E-8 --2.5 x 1E-4 erg cm-2, and peak fluxes in the range 0.11
- 56 ph cm-2 s-1. While most of the spectra are well fitted by a power law with
photon index ~ 1.6, we found that 9 bursts are better described by a cut-off
power law, resulting in Ep values in the range 35--190 keV. Altough these
results are comparable with those obtained with BAT onboard Swift, there is a
marginal evidence that ISGRI detects dimmer bursts than Swift/BAT. Using the
revised spectral parameters and an updated sky exposure map that takes into
account also the effects of the GRB trigger efficiency, we strengthen the
evidence for a spatial correlation with the super galactic plane of the faint
bursts with long spectral lag (Foley et al.,2008).Comment: Corrected some typos, added some references; Accepted by Astronomy &
Astrophysics, in pres
Vaccination against Bm86 Homologues in Rabbits Does Not Impair Ixodes ricinus Feeding or Oviposition
Human tick-borne diseases that are transmitted by Ixodes ricinus, such as Lyme
borreliosis and tick borne encephalitis, are on the rise in Europe.
Diminishing I. ricinus populations in nature can reduce tick exposure to
humans, and one way to do so is by developing an anti-vector vaccine against
tick antigens. Currently, there is only one anti-vector vaccine available
against ticks, which is a veterinary vaccine based on the tick antigen Bm86 in
the gut of Rhipicephalus microplus. Bm86 vaccine formulations cause a
reduction in the number of Rhipicephalus microplus ticks that successfully
feed, i.e. lower engorgement weights and a decrease in the number of
oviposited eggs. Furthermore, Bm86 vaccines reduce transmission of bovine
Babesia spp. Previously two conserved Bm86 homologues in I. ricinus ticks,
designated as Ir86-1 and Ir86-2, were described. Here we investigated the
effect of a vaccine against recombinant Ir86-1, Ir86-2 or a combination of
both on Ixodes ricinus feeding. Recombinant Ixodes ricinus Bm86 homologues
were expressed in a Drosophila expression system and rabbits were immunized
with rIr86-1, rIr86-2, a combination of both or ovalbumin as a control. Each
animal was infested with 50 female adults and 50 male adults Ixodes ricinus
and tick mortality, engorgement weights and egg mass were analyzed. Although
serum IgG titers against rIr86 proteins were elicited, no effect was found on
tick feeding between the rIr86 vaccinated animals and ovalbumin vaccinated
animals. We conclude that vaccination against Bm86 homologues in Ixodes
ricinus is not an effective approach to control Ixodes ricinus populations,
despite the clear effects of Bm86 vaccination against Rhipicephalus microplus
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