Masaru Shibata

Matter effects on binary neutron star waveforms

Using an extended set of equations of state and a multiple-group multiple-code collaborative effort to generate waveforms, we improve numerical-relativity-based data-analysis estimates of the measurability of matter effects in neutron-star binaries. We vary two parameters of a parameterized piecewise-polytropic equation of state (EOS) to analyze the measurability of EOS properties, via a parameter {Lambda} that characterizes the quadrupole deformability of an isolated neutron star. We find that, to within the accuracy of the simulations, the departure of the waveform from point-particle (or spinless double black-hole binary) inspiral increases monotonically with {Lambda}, and changes in the EOS that did not change {Lambda} are not measurable. We estimate with two methods the minimal and expected measurability of {Lambda} in second- and third- generation gravitational-wave detectors. The first estimate, using numerical waveforms alone, shows two EOS which vary in radius by 1.3km are distinguishable in mergers at 100Mpc. The second estimate relies on the construction of hybrid waveforms by matching to post-Newtonian inspiral, and estimates that the same EOS are distinguishable in mergers at 300Mpc. We calculate systematic errors arising from numerical uncertainties and hybrid construction, and we estimate the frequency at which such effects would interfere with template-based searches.

Bar-mode instability of a rapidly spinning black hole in higher dimensions: Numerical simulation in general relativity

Numerical-relativity simulation is performed for rapidly spinning black holes (BHs) in a higher-dimensional spacetime of special symmetries for the dimensionality 6{ q{sub crit} cannot be a stationary product in the particle accelerators,morexa0» even if it would be formed as a consequence of a TeV-gravity hypothesis. Its implications for the phenomenology of a mini BH are discussed.«xa0less

NAD-dependent histone deacetylase, SIRT1, plays essential roles in the maintenance of hematopoietic stem cells.

Sir2 has been shown to be essential for transcriptional silencing and longevity provided by calorie restriction in Saccharomyces cerevisiae and Caenorhabditis elegans. In this study, we investigated the role for its mammalian homologue, SIRT1, in hematopoietic cells. SIRT1 inhibitor, nicotinamide (NA), promoted and its activator, resveratrol, inhibited the differentiation of murine bone marrow c-Kit(high)Sca-1(+)Lineage(-) (KSL) cells during the culture system ex vivo. To further clarify the roles of SIRT1 in hematopoietic cells, we isolated KSL cells from fetal liver of SIRT1 knockout (KO) mice and cultured them for 5days, because SIRT1 KO mice die shortly after the delivery. In agreement with the results from the experiments using NA and resveratrol, KSL cells isolated from SIRT1 KO mice more apparently differentiated and lost the KSL phenotype than those from wild-type (WT) mice. Furthermore, in each of colony assay, replating assay, or serial transplantation assay, SIRT1 KO KSL cells lost earlier the characteristics of stem cells than WT KSL cells. In addition, we found that SIRT1 maintains prematurity of hematopoietic cells through ROS elimination, FOXO activation, and p53 inhibition. These results suggest that SIRT1 suppresses differentiation of hematopoietic stem/progenitor cells and contributes to the maintenance of stem cell pool.

Chapter 1 Black Hole Perturbation

We present analytic calculations of gravitational waves from a particle orbiting a black hole. We first review the Teukolsky formalism for dealing with the gravitational perturbation of a black hole. Then we develop a systematic method to calculate higher order post-Newtonian corrections to the gravitational waves emitted by an orbiting particle. As applications of this method, we consider orbits that are nearly circular, including exactly circular ones, slightly eccentric ones and slightly inclined orbits off the equatorial plane of a Kerr black hole and give the energy flux and angular momentum flux formulas at infinity with higher order post-Newtonian corrections. Using a different method that makes use of an analytic series representation of the solution of the Teukolsky equation, we also give a post-Newtonian expanded formula for the energy flux absorbed by a Kerr black hole for a circular orbit.

C-terminal mutation of RUNX1 attenuates the DNA-damage repair response in hematopoietic stem cells

Loss-of-function mutations of RUNX1 have been found in acute myeloid leukemia (AML) and myelodysplastic syndromes (MDSs). Although several reports have suggested roles for RUNX1 as a tumor suppressor, its precise function remains unknown. Because gene alterations of RUNX1 by themselves do not lead to the development of leukemia in mouse models, additional mutation(s) would be required for leukemia development. Here, we report that the C-terminal deletion mutant of RUNX1, RUNX1dC, attenuates DNA-damage repair responses in hematopoietic stem/progenitor cells. γH2AX foci, which indicate the presence of DNA double-strand breaks, were more abundantly accumulated in RUNX1dC-transduced lineage−Sca1+c-kit+ (LSK) cells than in mock-transduced LSK cells both in a steady state and after γ-ray treatment. Expression profiling by real-time -PCR array revealed RUNX1dC represses the expression of Gadd45a, a sensor of DNA stress. Furthermore, bone marrow cells from MDS/AML patients harboring the RUNX1-C-terminal mutation showed significantly lower levels of GADD45A expression compared with those from MDS/AML patients with wild-type RUNX1. As for this mechanism, we found that RUNX1 directly regulates the transcription of GADD45A and that RUNX1 and p53 synergistically activate the GADD45A transcription. Together, these results suggest Gadd45a dysfunction due to RUNX1 mutations can cause additional mutation(s) required for multi-step leukemogenesis.

Gravitational waves from a spinning particle in circular orbits around a rotating black hole

Using the Teukolsky and Sasaki-Nakamura formalisms for the perturbations around a Kerr black hole, we calculate the energy flux of gravitational waves induced by a spinning particle of mass m and spin S moving in circular orbits near the equatorial plain of a rotating black hole of mass M(@m) and spin Ma . The calculations are performed by using the recently developed post-Newtonian expansion technique of the Teukolsky equation. To evaluate the source terms of perturbations caused by a spinning particle, we use the equations of motion of a spinning particle derived by Papapetrou and the energy-momentum tensor of a spinning particle derived by Dixon. We present the post-Newtonian formula of the gravitational wave luminosity up to the order (v/c) 5 beyond the quadrupole formula including the linear order of particle spin. The results obtained in this paper will be an important guideline to the post-Newtonian calculation of the inspiral of two spinning compact objects. @S0556-2821~96!02016-4#

Relativistic formalism for computation of irrotational binary stars in quasiequilibrium states

We present relativistic hydrostatic equations for obtaining irrotational binary neutron stars in quasiequilibrium states in the

Post-Newtonian expansion of gravitational waves from a particle in circular orbit around a rotating black hole: Up to O(v8) beyond the quadrupole formula.

3+1

BCR-ABL but Not JAK2 V617F Inhibits Erythropoiesis through the Ras Signal by Inducing p21CIP1/WAF1

formalism. The equations derived here are different from those previously given by Bonazzola, Gourgoulhon, and Marck, and have a simpler and more tractable form for computation in numerical relativity. We also present hydrostatic equations for computation of equilibrium irrotational binary stars in the first post-Newtonian order.

Numerical Study on the Hydrodynamic Instability of Binary Stars in the First Post Newtonian Approximation of General Relativity

Extending a method developed by Sasaki in the Schwarzschild case and by Shibata, Sasaki, Tagoshi, and Tanaka in the Kerr case, we calculate the post-Newtonian expansion of the gravitational wave luminosities from a test particle in circular orbit around a rotating black hole up to