6,199 research outputs found
GRB/GW association: Long-short GRB candidates, time-lag, measuring gravitational wave velocity and testing Einstein's equivalence principle
Short-duration gamma-ray bursts (SGRBs) are widely believed to be powered by
the mergers of compact binaries, such as binary neutron stars or possibly
neutron star-black hole binaries. Though the prospect of detecting SGRBs with
gravitational wave (GW) signals by the advanced Laser Interferometer
Gravitational-Wave Observatory (LIGO)/VIRGO network is promising, no known SGRB
has been found within the expected advanced LIGO/VIRGO sensitivity range for
binary neutron star systems. We find, however, that the two long-short GRBs
(GRB 060505 and GRB 060614) may be within the horizon of advanced GW detectors.
In the upcoming era of GW astronomy, the merger origin of some long-short GRBs,
as favored by the macronova signature displayed in GRB 060614, can be
unambiguously tested. The model-dependent time lags between the merger and the
onset of the prompt emission of the GRB are estimated. The comparison of such
time lags between model predictions and the real data expected in the era of
the GW astronomy would be helpful in revealing the physical processes taking
place at the central engine (including the launch of the relativistic outflow,
the emergence of the outflow from the dense material ejected during the merger,
and the radiation of gamma rays). We also show that the speed of GWs, with or
without a simultaneous test of Einstein's equivalence principle, can be
directly measured to an accuracy of or
even better in the advanced LIGO/VIRGO era. The Astrophysical Journal, VolumeComment: 12 pages, 3 figures, published in The Astrophysical Journa
The Differentiation Balance of Bone Marrow Mesenchymal Stem Cells Is Crucial to Hematopoiesis.
Bone marrow mesenchymal stem cells (BMSCs), the important component and regulator of bone marrow microenvironment, give rise to hematopoietic-supporting stromal cells and form hematopoietic niches for hematopoietic stem cells (HSCs). However, how BMSC differentiation affects hematopoiesis is poorly understood. In this review, we focus on the role of BMSC differentiation in hematopoiesis. We discussed the role of BMSCs and their progeny in hematopoiesis. We also examine the mechanisms that cause differentiation bias of BMSCs in stress conditions including aging, irradiation, and chemotherapy. Moreover, the differentiation balance of BMSCs is crucial to hematopoiesis. We highlight the negative effects of differentiation bias of BMSCs on hematopoietic recovery after bone marrow transplantation. Keeping the differentiation balance of BMSCs is critical for hematopoietic recovery. This review summarises current understanding about how BMSC differentiation affects hematopoiesis and its potential application in improving hematopoietic recovery after bone marrow transplantation
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