160 research outputs found

    A Stellar-mass Black Hole in the Ultra-luminous X-ray Source M82 X-1?

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    We have analyzed the archival XMM-Newton data of the bright Ultra-Luminous X-ray Source (ULX) M82 X-1 with an 105 ksec exposure when the source was in the steady state. Thanks to the high photon statistics from the large effective area and long exposure, we were able to discriminate different X-ray continuum spectral models. Neither the standard accretion disk model (where the radial dependency of the disk effective temperature is T(r) \propto r^-3/4) nor a power-law model gives a satisfactory fit. In fact, observed curvature of the M82 X-1 spectrum was just between those of the two models. When the exponent of the radial dependence (p in T(r) \propto r^-p) of the disk temperature is allowed to be free, we obtained p =0.61^+0.03_-0.02. Such a reduction of p from the standard value 3/4 under extremely high mass accretion rates is predicted from the accretion disk theory as a consequence of the radial energy advection. Thus, the accretion disk in M82 X-1 is considered to be in the Slim disk state, where an optically thick Advection Dominant Accretion Flow (ADAF) is taking place. We have applied a theoretical slim disk spectral model to M82 X-1, and estimated the black hole mass ~ 19-32 M_odot. We propose that M82 X-1 is a relatively massive stellar black hole which has been produced through evolution of an extremely massive star, shining at a super-Eddington luminosity by several times the Eddington limit.Comment: 12 pages, 2 figures, Accepted for ApJ

    Left ventricular deformation and torsion assessed by speckle-tracking echocardiography in patients with mutated transthyretin-associated cardiac amyloidosis and the effect of diflunisal on myocardial function

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    AbstractBackgroundMutated transthyretin-associated (ATTRm) amyloidosis with heart failure is associated with decreased longitudinal left ventricular (LV) myocardial contraction, as measured by strain Doppler echocardiography. We sought to clarify whether speckle-tracking echocardiography (STE) would provide useful information in patients with ATTRm cardiac amyloidosis.MethodsOne hundred twenty-three consecutive patients with ATTRm amyloidosis were divided into 3 groups. Group 1 had no evidence of cardiac involvement (n=47), group 2 had heart involvement but no congestive heart failure (CHF) and/or serum brain natriuretic peptide (BNP) levels <100pg/mL (n=35), and group 3 had heart involvement and CHF and/or serum BNP levels ≥100pg/mL (n=41). All patients underwent standard 2-dimensional (2D), Doppler echo, and STE.ResultsBy standard 2D and Doppler echo, differences in parameters were only apparent between group 3 and groups 1 and 2. Global circumferential strains by STE at each LV level and LV torsion were different between group 1 and groups 2 and 3, but not between group 2 and group 3. In contrast, global longitudinal LV strain showed significant intergroup differences (−17.3±2.3%, −13.3±2.3%, −9.9±3.3% for groups 1 to 3, respectively, P<0.0001). Radial strain also showed significant intergroup differences for each basal LV segment. Among 41 patients who could have been followed up after 1year, 34 patients with diflunisal treatment had shown improvement in apical rotation and torsion without deterioration in multidirectional strains.ConclusionATTRm cardiac amyloidosis is characterized by progressive impairment in longitudinal and basal LV radial function when global circumferential shortening and torsion remain unchanged

    Lack of association between PER3 variable number tandem repeat and circadian rhythm sleep-wake disorders.

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    Circadian rhythm sleep-wake disorders (CRSWDs) are characterized by disturbed sleep-wake patterns. Wegenotyped a PER3 variable number tandem repeat (VNTR) in 248 CRSWD individuals and 925 controls andfound no significant association between the VNTR and CRSWDs or morningness-eveningness (diurnal)preferences in the Japanese population. Although the VNTR has been associated with circadian and sleep phenotypes in some other populations, the polymorphism may not be a universal genetic marker

    Screening of clock gene polymorphisms demonstrates association of a PER3 polymorphism with morningness-eveningness preference and circadian rhythm sleep disorder.

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    A system of self-sustained biological clocks controls the 24-h rhythms of behavioral and physiological processes such as the sleep-wake cycle. The circadian clock system is regulated by transcriptional and translational negative feedback loops of multiple clock genes. Polymorphisms in circadian clock genes have been associated with morningness-eveningness (diurnal) preference, familial advanced sleep phase type (ASPT), and delayed sleep phase type (DSPT). We genotyped single-nucleotide polymorphisms in circadian clock genes in 182 DSPT individuals, 67 free-running type (FRT) individuals, and 925 controls. The clock gene polymorphisms were tested for associations with diurnal preference and circadian rhythm sleep disorder (CRSD) phenotypes. The PER3 polymorphism (rs228697) was significantly associated with diurnal preference and the FRT phenotype. The minor allele of rs228697 was more prevalent in evening types than in morning types (sex-adjusted odds ratio (OR), 2.483, Bonferroni-corrected P = 0.012) and in FRT individuals compared with the controls (age- and sex-adjusted OR, 2.021, permutated P = 0.017). Our findings support the notion that PER3 polymorphisms could be a potential genetic marker for an individual\u27s circadian and sleep phenotypes

    Status of the RFQ linac installation and conditioning of the Linear IFMIF Prototype Accelerator

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    Abstract The Radio Frequency Quadrupole (RFQ) linac and 1.6 MW RF power system of the Linear IFMIF Prototype Accelerator (LIPAc) facility in the International Fusion Energy Research Center (IFERC) in Rokkasho (Japan) has been installed and conditioned. During the assembly and tuning process, the RFQ cavity was protected with a temporary tent from the potential deterioration of performance caused by dust. The vacuum in the cavity was improved through the 100 °C baking process of the cavity. The high power test of the 175 MHz RF systems up to 200 kW in CW for each of the eight RF chains was performed for checking its stable output reproducibility in Japan, before connecting 9–3/16 inch coaxial transmission lines from the RF chains to the RF input couplers of the cavity. It was confirmed that the eight RF chains provided the balanced RF power to the single RFQ cavity in-phase using a feedback loop and a synchronization system. The peak power in the cavity achieved 150 kW in the pulsed mode, which corresponds approximately to the required electric field to accelerate proton beam. Such RF conditioning process is ongoing to achieve 600 kW approximately required for deuteron beam commissioning planned in 2018

    The ASTRO-H X-ray Observatory

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    The joint JAXA/NASA ASTRO-H mission is the sixth in a series of highly successful X-ray missions initiated by the Institute of Space and Astronautical Science (ISAS). ASTRO-H will investigate the physics of the high-energy universe via a suite of four instruments, covering a very wide energy range, from 0.3 keV to 600 keV. These instruments include a high-resolution, high-throughput spectrometer sensitive over 0.3-2 keV with high spectral resolution of Delta E < 7 eV, enabled by a micro-calorimeter array located in the focal plane of thin-foil X-ray optics; hard X-ray imaging spectrometers covering 5-80 keV, located in the focal plane of multilayer-coated, focusing hard X-ray mirrors; a wide-field imaging spectrometer sensitive over 0.4-12 keV, with an X-ray CCD camera in the focal plane of a soft X-ray telescope; and a non-focusing Compton-camera type soft gamma-ray detector, sensitive in the 40-600 keV band. The simultaneous broad bandpass, coupled with high spectral resolution, will enable the pursuit of a wide variety of important science themes.Comment: 22 pages, 17 figures, Proceedings of the SPIE Astronomical Instrumentation "Space Telescopes and Instrumentation 2012: Ultraviolet to Gamma Ray

    The Quiescent Intracluster Medium in the Core of the Perseus Cluster

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    Clusters of galaxies are the most massive gravitationally-bound objects in the Universe and are still forming. They are thus important probes of cosmological parameters and a host of astrophysical processes. Knowledge of the dynamics of the pervasive hot gas, which dominates in mass over stars in a cluster, is a crucial missing ingredient. It can enable new insights into mechanical energy injection by the central supermassive black hole and the use of hydrostatic equilibrium for the determination of cluster masses. X-rays from the core of the Perseus cluster are emitted by the 50 million K diffuse hot plasma filling its gravitational potential well. The Active Galactic Nucleus of the central galaxy NGC1275 is pumping jetted energy into the surrounding intracluster medium, creating buoyant bubbles filled with relativistic plasma. These likely induce motions in the intracluster medium and heat the inner gas preventing runaway radiative cooling; a process known as Active Galactic Nucleus Feedback. Here we report on Hitomi X-ray observations of the Perseus cluster core, which reveal a remarkably quiescent atmosphere where the gas has a line-of-sight velocity dispersion of 164+/-10 km/s in a region 30-60 kpc from the central nucleus. A gradient in the line-of-sight velocity of 150+/-70 km/s is found across the 60 kpc image of the cluster core. Turbulent pressure support in the gas is 4% or less of the thermodynamic pressure, with large scale shear at most doubling that estimate. We infer that total cluster masses determined from hydrostatic equilibrium in the central regions need little correction for turbulent pressure.Comment: 31 pages, 11 Figs, published in Nature July

    Hitomi (ASTRO-H) X-ray Astronomy Satellite

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    The Hitomi (ASTRO-H) mission is the sixth Japanese x-ray astronomy satellite developed by a large international collaboration, including Japan, USA, Canada, and Europe. The mission aimed to provide the highest energy resolution ever achieved at E  >  2  keV, using a microcalorimeter instrument, and to cover a wide energy range spanning four decades in energy from soft x-rays to gamma rays. After a successful launch on February 17, 2016, the spacecraft lost its function on March 26, 2016, but the commissioning phase for about a month provided valuable information on the onboard instruments and the spacecraft system, including astrophysical results obtained from first light observations. The paper describes the Hitomi (ASTRO-H) mission, its capabilities, the initial operation, and the instruments/spacecraft performances confirmed during the commissioning operations for about a month
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