385 research outputs found
Extended Emission of Short Gamma-Ray Bursts
Preliminary results of our analysis on the extended emission of short/medium
duration GRBs observed with Swift/BAT are presented. The Bayesian blocks
algorithm is used to analyze the burst durations and the temporal structure of
the lightcurves in different energy bands. We show here the results of three
bursts (GRBs 050724, 061006 and 070714B) that have a prominent soft extended
emission component in our sample. The extended emission of these bursts is a
continuous, flickering-liked component, lasting seconds post the GRB
trigger at 15-25 keV bands. Without considering this component, the three
bursts are classified as short GRBs, with seconds. GRB 060614
has an emission component similar to the extended emission, but this component
has pulse-liked structure, possibly indicating that this emission component is
different from that observed in GRBs 050724, 061006, and 070714B. Further
analysis on the spectral evolution behavior of the extended emission component
is on going.Comment: 2008 Nanjing GRB Conferenc
Multiphase transport model for heavy ion collisions at RHIC
Using a multiphase transport model (AMPT) with both partonic and hadronic
interactions, we study the multiplicity and transverse momentum distributions
of charged particles such as pions, kaons and protons in central Au+Au
collisions at RHIC energies. Effects due to nuclear shadowing and jet quenching
on these observables are also studied. We further show preliminary results on
the production of multistrange baryons from the strangeness-exchange reactions
during the hadronic stage of heavy ion collisions.Comment: 4 pages, 4 figures, espcrc1.sty included, presented at 15th
International Conference on Ultra-Relativistic Nucleus-Nucleus Collisions
(QM2001), Long Island, New York, January 200
Quantitative analysis of the genes affecting development of the hypopharyngeal gland in honey bees (Apis mellifera L.)
Royal jelly has many important biological functions, however the molecular mechanism of royal jelly secretion in hypopharyngeal gland (HG) is still not well understood. In our previously study, six genes (SV2C, eIF-4E, PDK1, IMP, cell growth-regulating nucleolar protein and TGF-βR1) have been shown to might be associated with royal jelly secretion. In this study, the relative expression levels of these genes were examined in the hypopharyngeal gland of workers at different developmental stages (nurse, forager and reversed nurse stages). The results indicated that the relative expression levels of SV2C, eIF-4E, IMP, cell growth-regulating nucleolar protein and TGF-βR1 were reversed at reversed nurse stage compared to forager stage. We concluded that these genes are possibly candidates related to hypopharyngeal gland development or royal jelly secretion
A Multi-Phase Transport Model for Relativistic Heavy Ion Collisions
We describe in detail how the different components of a multi-phase transport
(AMPT) model, that uses the Heavy Ion Jet Interaction Generator (HIJING) for
generating the initial conditions, Zhang's Parton Cascade (ZPC) for modeling
partonic scatterings, the Lund string fragmentation model or a quark
coalescence model for hadronization, and A Relativistic Transport (ART) model
for treating hadronic scatterings, are improved and combined to give a coherent
description of the dynamics of relativistic heavy ion collisions. We also
explain the way parameters in the model are determined, and discuss the
sensitivity of predicted results to physical input in the model. Comparisons of
these results to experimental data, mainly from heavy ion collisions at the
Relativistic Heavy Ion Collider (RHIC), are then made in order to extract
information on the properties of the hot dense matter formed in these
collisions.Comment: 33 pages, 38 figures, revtex. Added 9 figures, version published in
Phys. Rev. C. The full source code of the AMPT model in the Fortran 77
language and instructions for users are available from the EPAPS ftp site
(ftp://ftp.aip.org/epaps/phys_rev_c/E-PRVCAN-72-781512/) and the OSCAR
website (http://www-cunuke.phys.columbia.edu/OSCAR/
Transplantation of a Peripheral Nerve with Neural Stem Cells Plus Lithium Chloride Injection Promote the Recovery of Rat Spinal Cord Injury
Transplantation of neural stem cells (NSCs) holds great potential for the treatment of spinal cord injury (SCI). However, transplanted NSCs poorly survive in the SCI environment. We injected NSCs into tibial nerve and transplanted tibial nerve into a hemisected spinal cord and investigated the effects of lithium chloride (LiCl) on the survival of spinal neurons, axonal regeneration, and functional recovery. Our results show that most of the transplanted NSCs expressed glial fibrillary acidic protein, while there was no obvious expression of nestin, neuronal nuclei, or acetyltransferase found in NSCs. LiCl treatment produced less macrosialin (ED1) expression and axonal degeneration in tibial nerve after NSC injection. Our results also show that a regimen of LiCl treatment promoted NSC differentiation into NF200-positive neurons with neurite extension into the host spinal cord. The combination of tibial nerve transplantation with NSCs and LiCl injection resulted in more host motoneurons surviving in the spinal cord, more regenerated axons in tibial nerve, less glial scar area, and decreased ED1 expression. We conclude that lithium may have therapeutic potential in cell replacement strategies for central nervous system injury due to its ability to promote survival and neuronal generation of grafted NSCs and reduced host immune reaction
Detection of Quasi-periodic Oscillations in SGR 150228213
The detection of quasi-periodic oscillations (QPOs) in magnetar giant flares
(GFs) has brought a new perspective to study the mechanism of magnetar bursts.
Due to the scarcity of GFs, searching QPOs from magnetar short bursts is
reasonable. Here we report the detection of a high frequency QPO at
approximately 110 Hz and a wide QPO at approximately 60 Hz in a short magnetar
burst SGR 150228213, with a confidence level of 3.35. This burst was
initially attributed to 4U 0142+61 by /GBM on location, but we haven't
detected such QPOs in other bursts from this magnetar. We also found that there
was a repeating fast radio burst associated with SGR 150228213 on location.
Finally, we discuss the possible origins of SGR 150228213
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