29,948 research outputs found
A two component jet model for the X-ray afterglow flat segment in short GRB 051221A
In the double neutron star merger or neutron star-black hole merger model for
short GRBs, the outflow launched might be mildly magnetized and neutron rich.
The magnetized neutron-rich outflow will be accelerated by the magnetic and
thermal pressure and may form a two component jet finally, as suggested by
Vlahakis, Peng & K\"{o}nigl (2003). We show in this work that such a two
component jet model could well reproduce the multi-wavelength afterglow
lightcurves, in particular the X-ray flat segment, of short GRB 051221A. In
this model, the central engine need not to be active much longer than the
prompt ray emission.Comment: 11 pages, 2 figure; Accepted for publication by ApJ
The X-ray afterglow of GRB 081109A: clue to the wind bubble structure
We present the prompt BAT and afterglow XRT data of Swift-discovered
GRB081109A up to ~ 5\times 10^5 sec after the trigger, and the early
ground-based optical follow-ups. The temporal and spectral indices of the X-ray
afterglow emission change remarkably. We interpret this as the GRB jet first
traversing the freely expanding supersonic stellar wind of the progenitor with
density varying as . Then after approximately 300 sec the
jet traverses into a region of apparent constant density similar to that
expected in the stalled-wind region of a stellar wind bubble or the
interstellar medium (ISM). The optical afterglow data are generally consistent
with such a scenario. Our best numerical model has a wind density parameter
{, a density of the stalled wind ,
and a transition radius cm}. Such a transition
radius is smaller than that predicted by numerical simulations of the stellar
wind bubbles and may be due to a rapidly evolving wind of the progenitor close
to the time of its core-collapse.Comment: 7 pages, 5 figures, 2 tables, MNRAS accepted for publicatio
Reputation: configuring the symmetrical and asymmetrical paths to architecture in a retail setting
Grounded in social identity and attribution theories, this study focuses on the effect of architecture and its components on reputation. The relationships conceptualised were evaluated using data collected from a survey of 489 online and offline UK retail consumers and employees. To accommodate the equifinality and complexity of these relationships, this study employs fuzzy set qualitative comparative analysis, predictive validity and fit validity chec
Effect of Corynoline Isolated from Corydalis bungeana Turcz on Lipopolysaccharides-Induced Sepsis In vivo and In vitro
Purpose: To investigate the protective effect of corynoline isolated from Corydalis bungeana Turcz on lipopolysaccharides (LPS)-induced sepsis, and determine the possible mechanism of anti-sepsis effect of the isolated corynoline.Methods: Corynoline was extracted by column chromatography. LPS (100 ng/mL) was used to induce the release of TNF-α and IL-6 in RAW 264.7 cells, and the isolated corynoline was added. ELISA method was used to determine the levels of TNF-α and IL- 6. Furthermore, sepsis in mice was established by injection of LPS (2 mg/kg, i.v.), and the levels of TNF- α and IL-6 in plasma were determined by ELISA method. For survival rate test, LPS (15 mg/kg, i.v.) and heat-killed E. coli (1.0 ~1011 CFU/kg, i.v.) were used to establish sepsis in mice model, and the mice were observed in 7 days.Results: The results indicate that corynoline significantly elevated the survival rate of septic mice induced by LPS and heat-killed E. coli, in a dose-dependent manner (p < 0.05). Corynoline decreased the release of TNF-α and IL-6 induced by LPS, in a dose-dependent manner (p < 0.05).Conclusion: Treatment with corynoline significantly inhibits the mortality of LPS-induced septic mice, and the mechanism of action is probably related to the decrease of TNF-α and IL-6 release. Thus corynoline has the potential to be developed as an effective and safe drug for treating sepsis.Keywords: Corynoline, Corydalis bungeana, Sepsis, Lipopolysaccharides, TNF-α, IL-
Parton Distributions at Hadronization from Bulk Dense Matter Produced at RHIC
We present an analysis of , , and spectra from
Au+Au collisions at GeV in terms of distributions of
effective constituent quarks at hadronization. Consistency in quark ratios
derived from various hadron spectra provides clear evidence for hadron
formation dynamics as suggested by quark coalescence or recombination models.
We argue that the constituent quark distribution reflects properties of the
effective partonic degrees of freedom at hadronization. Experimental data
indicate that strange quarks have a transverse momentum distribution flatter
than that of up/down quarks consistent with hydrodynamic expansion in partonic
phase prior to hadronization. After the AMPT model is tuned to reproduce the
strange and up/down quark distributions, the model can describe the measured
spectra of hyperons and mesons very well where hadrons are formed
through dynamical coalescence.Comment: 5 pages, 3 figures, two more paragraph added to address the referee's
comment, figure updated to include the KET scale. Accepted version to appear
in Phys. Rev.
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