989 research outputs found
A Stellar-mass Black Hole in the Ultra-luminous X-ray Source M82 X-1?
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
Finite element analysis of tube drawing process with diameter expansion
This paper presents a tube drawing process with diameter expansion for producing a thin-walled tube effectively. In this proposed process, the tube was flared by a plug pushing into the tube, and then the tube was expanded by drawing the plug in the tube axial direction with chucking the flared tube edge. Optimum plug shape, such as the plug half angle and the corner radius, was investigated by a series of analyses using the finite element method (FEM) for improving the forming limit and the dimension accuracy. At first, a friction coefficient was determined to 0.3 by a comparison of the flaring limit between the analysis and the experiment of the tube flaring. As a result of the analyses in the drawing with the diameter expansion, the forming limit was high when the plug half angle was set to 18~30°. The thickness reduction ratio increased with an increase in the expansion ratio and the plug half angle. In addition, the overshoot, which is a difference between the plug diameter and the tube inner diameter after the drawing, was prevented by using the plug with the corner radius of 20 mm
Zero-shot domain adaptation of anomalous samples for semi-supervised anomaly detection
Semi-supervised anomaly detection~(SSAD) is a task where normal data and a
limited number of anomalous data are available for training. In practical
situations, SSAD methods suffer adapting to domain shifts, since anomalous data
are unlikely to be available for the target domain in the training phase. To
solve this problem, we propose a domain adaptation method for SSAD where no
anomalous data are available for the target domain. First, we introduce a
domain-adversarial network to a variational auto-encoder-based SSAD model to
obtain domain-invariant latent variables. Since the decoder cannot reconstruct
the original data solely from domain-invariant latent variables, we conditioned
the decoder on the domain label. To compensate for the missing anomalous data
of the target domain, we introduce an importance sampling-based weighted loss
function that approximates the ideal loss function. Experimental results
indicate that the proposed method helps adapt SSAD models to the target domain
when no anomalous data are available for the target domain
Attitude Control Flight Experience: Coping with Solar Radiation and Ion Engines Leak Thrust in Hayabusa (MUSES-C)
The paper presents the attitude reorientation taking the advantage of solar radiation pressure without use of any fuel aboard. The strategy had been adopted to make Hayabusa spacecraft keep pointed toward the Sun for several months, while spinning. The paper adds the above mentioned results reported in Sedona this February showing another challenge of combining ion engines propulsion tactically balanced with the solar radiation torque with no spin motion. The operation has been performed since this March for a half year successfully. The flight results are presented with the estimated solar array panel diffusion coefficient and the ion engine's swirl torque
Taste hyposensitivity in Japanese schoolchildren
BACKGROUND: There is some research on taste disorder/hyposensitivity in special groups such as the elderly or patients presenting with specific taste problems, however few studies have been conducted among young populations. The objectives of this study were to estimate the prevalence of taste hyposensitivity and to investigate the relationship between taste hyposensitivity and oral health status in Japanese schoolchildren. METHODS: Subjects were 237 primary and 112 junior high school students in Saitama Prefecture, Japan. In total, 349 (boys: 181, girls: 168) students aged 6–15 years participated in the study. Oral examinations and whole-mouth taste tests using four tastes (sweet, salt, sour and bitter) solutions were conducted on the subjects. A subject who could not recognize the taste of the solution was defined as demonstrating hyposensitivity. RESULTS: Hyposensitivity was observed in 6.3% of all subjects for sweet-taste, 14.3% for salt-taste, 20.9% for sour-taste and 6.0% for bitter-taste. The prevalence of sweet, sour and bitter-taste hyposensitivity decreased as the subjects’ grade advanced. In contrast, the prevalence of salt-taste hyposensitivity increased in 7(th)-9(th) grade subjects. Furthermore, the prevalence of bitter-taste hyposensitivity was significantly higher in males than females among 1(st)-3(rd) graders. Taste hyposensitivity had little association with oral health status, such as decayed teeth, filled teeth, dental plaque, gingival status and tongue coating. CONCLUSIONS: In this study, taste hyposensitivity was observed in 6.0%-20.9% of the students. There was little association between taste hyposensitivity and oral health status. The current study implies that the factors affecting the taste hyposensitivity in children may different from those in the elderly. Therefore it is necessary to further investigate the causes of taste hyposensitivity among younger generation
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