3,306 research outputs found
Gravitational Wave Background from Neutrino-Driven Gamma-Ray Bursts
We discuss the gravitational wave background (GWB) from a cosmological
population of gamma-ray bursts (GRBs). Among various emission mechanisms for
the gravitational waves (GWs), we pay a particular attention to the vast
anisotropic neutrino emissions from the accretion disk around the black hole
formed after the so-called failed supernova explosions. The produced GWs by
such mechanism are known as burst with memory, which could dominate over the
low-frequency regime below \sim 10Hz. To estimate their amplitudes, we derive
general analytic formulae for gravitational waveform from the axisymmetric
jets. Based on the formulae, we first quantify the spectrum of GWs from a
single GRB. Then, summing up its cosmological population, we find that the
resultant value of the density parameter becomes roughly \Omega_{GW} \approx
10^{-20} over the wide-band of the low-frequency region, f\sim 10^{-4}-10^1Hz.
The amplitude of GWB is sufficiently smaller than the primordial GWBs
originated from an inflationary epoch and far below the detection limit.Comment: 6 pages, 4 figures, accepted for publication in MNRA
Gravitational Wave Astrometry for Rapidly Rotating Neutron Stars and Estimation of Their Distances
We discuss an astrometric timing effect on data analysis of continuous
gravitational waves from rapidly rotating isolated neutron stars. Special
attention is directed to the possibility of determining their distances by
measuring the curvature of the wave fronts. We predict that if continuous
gravitational waves from an unknown neutron star with a stable rotation are
detected around 1kHz within 1/3yr by initial LIGO detectors and the ellipticity
parameter epsilon is smaller than 10^{-6}, the distance r to the source can be
estimated with relative error \Delta r/r of \sim 10% by using the broad band
configuration of advanced LIGO detectors over 3 years. By combining the
observed amplitude of the waves with the estimated distance, information on the
parameter can be obtained purely through gravitational wave
measurements.Comment: 6 pages, 1 figure, to appear in PR
Thermal leptogenesis in brane world cosmology
The thermal leptogenesis in brane world cosmology is studied. In brane world
cosmology, the expansion law is modified from the four-dimensional standard
cosmological one at high temperature regime in the early universe. As a result,
the well-known upper bound on the lightest light neutrino mass induced by the
condition for the out-of-equilibrium decay of the lightest heavy neutrino,
eV, can be moderated to be in the case of with the
lightest heavy neutrino mass () and the ``transition temperature''
(), at which the modified expansion law in brane world cosmology is
smoothly connecting with the standard one. This implies that the degenerate
mass spectrum of the light neutrinos can be consistent with the thermal
leptogenesis scenario. Furthermore, as recently pointed out, the gravitino
problem in supersymmetric case can be solved if the transition temperature is
low enough GeV. Therefore, even in the supersymmetric
case, thermal leptogenesis scenario can be successfully realized in brane world
cosmology.Comment: 9 pages, final versio
Pengenalan Pahlawan Indonesia Berbasis Augmented Reality dengan Marker Uang Indonesia
Perjuangan para Pahlawan Indonesia atau bisa disebut dengan Pahlawan Nasional sangatlah luar biasa, mulai dari melawan penjajah sampai memajukan Bangsa Indonesia. Berkat perjuangan yang sangat heroik, Pahlawan Nasional diabadikan gambarnya di dalam uang kertas Indonesia. Namun banyak masyarakat yang tidak mengetahui sejarah dari para Pahlawan Nasional yang terdapat pada uang kertas Indonesia terbaru tahun 2014. Berdasarkan hal tersebut penulis berusaha menyajikan suatu alternatif aplikasi dalam menampilkan 3D dan sejarah dari masing-masing Pahlawan Nasional yang terdapat pada uang kertas Indonesia dalam bentuk Augmented Reality dengan memanfaatkan smartphone android sebagai media penunjang dan uang kertas Indonesia sebagai marker. Dalam pembangunan aplikasi ini, metode yang digunakan adalah metode prototype. Prototype merupakan metodologi pengembangan software yang menitik beratkan pada pendekatan aspek desain, fungsi dan user-interface. Sistem prototyping dapat melakukan analisis, desain, dan tahapan pelaksanaan secara bersamaan agar cepat mengembangkan versi sederhana dari sistem yang diusulkan oleh user dan memberikannya kepada user untuk evaluasi dan pembenahan. Hasil analisis dan perancangan aplikasi ini memberikan kemudahan, meningkatkan efektivitas dan efisiensi bagi pengguna. Karena hanya bermodalkan smartphone android dan marker uang kertas Indonesia, pengguna hanya menjalankan aplikasi dan menyorotkan kamera smartphone ke uang kertas yang dimiliki kemuadian akan muncul 3D Pahlawan Indonesia yang terdapat pada uang yang disorotkan tersebut beserta indormasi atau sejarah dari Pahlawan tersebut
Loop quantum gravity effects on inflation and the CMB
In loop quantum cosmology, the universe avoids a big bang singularity and
undergoes an early and short super-inflation phase. During super-inflation,
non-perturbative quantum corrections to the dynamics drive an inflaton field up
its potential hill, thus setting the initial conditions for standard inflation.
We show that this effect can raise the inflaton high enough to achieve
sufficient e-foldings in the standard inflation era. We analyze the
cosmological perturbations generated when slow-roll is violated after
super-inflation, and show that loop quantum effects can in principle leave an
indirect signature on the largest scales in the CMB, with some loss of power
and running of the spectral index.Comment: revtex4, 5 pages, 3 figures, significant improvements in explanation
of quantization and perturbation issues; version to appear Classical and
Quantum Gravit
Heterogeneity of LL 5-7 chondrites in relation to HAYABUSA samples.
珏3ćæ„”ćç§ćŠă·ăłăăžăŠă /珏35ććæ„”éçłă·ăłăăžăŠă 11æ30æ„ïŒéïŒ ćœç«ćœèȘç 究æ 2éèŹ
A swollen phase observed between the liquid-crystalline phase and the interdigitated phase induced by pressure and/or adding ethanol in DPPC aqueous solution
A swollen phase, in which the mean repeat distance of lipid bilayers is
larger than the other phases, is found between the liquid-crystalline phase and
the interdigitated gel phase in DPPC aqueous solution. Temperature, pressure
and ethanol concentration dependences of the structure were investigated by
small-angle neutron scattering, and a bending rigidity of lipid bilayers was by
neutron spin echo. The nature of the swollen phase is similar to the anomalous
swelling reported previously. However, the temperature dependence of the mean
repeat distance and the bending rigidity of lipid bilayers are different. This
phase could be a precursor to the interdigitated gel phase induced by pressure
and/or adding ethanol.Comment: 7 pages, 6 figure
Stochastic backgrounds of gravitational waves from extragalactic sources
Astrophysical sources emit gravitational waves in a large variety of
processes occurred since the beginning of star and galaxy formation. These
waves permeate our high redshift Universe, and form a background which is the
result of the superposition of different components, each associated to a
specific astrophysical process. Each component has different spectral
properties and features that it is important to investigate in view of a
possible, future detection. In this contribution, we will review recent
theoretical predictions for backgrounds produced by extragalactic sources and
discuss their detectability with current and future gravitational wave
observatories.Comment: 10 pages, 9 figures, proceedings of the GWDAW 10 Conference,
submitted to Class. & Quantum Gra
Expression of p16, a Biomarker of HPV Infection, Is Associated With Esophageal Precancerous State After Allogeneic Hematopoietic Stem Cell Transplantation: New Tools for Early Diagnosis of This Fatal Disease
- âŠ