474 research outputs found
High-dispersion spectroscopic monitoring of the Be/X-ray binary A0535+26/V725 Tau I: The long-term profile variability
We report on optical high-dispersion spectroscopic monitoring observations of
the Be/X-ray binary A0535+26/V725 Tau, carried out from November 2005 to March
2009. The main aim of these monitoring observations is to study spectral
variabilities in the Be disc, on both the short (a week or so) and long (more
than hundreds of days) timescales, by taking long-term frequent observations.
Our four-year spectroscopic observations indicate that the V/R ratio, i.e., the
relative intensity of the violet (V) peak to the red (R) one, of the
double-peaked H-alpha line profile varies with a period of 500 days. The H-beta
line profile also varies in phase with the H-alpha profile. With these
observations covering two full cycles of the V/R variability, we reconstruct
the 2-D structure of the Be disc by applying the Doppler tomography method to
the H-alpha and H-beta emission line profiles, using a rigidly rotating frame
with the V/R variability period. The resulting disc structure reveals
non-axisymmetric features, which can be explained by a one-armed perturbation
in the Be disc. It is the first time that an eccentric disc structure is
directly detected by using a method other than the interferometric one.Comment: (10 pages, 9 figures, accepted to MNRAS
Amorphization under fracture surface in hydrogen-charged and low- temperature tensile-tested austenitic stainless steel
The microstructure just below the fracture surface in hydrogen-charged stable austenitic SUS 316L stainless steel, which was subjected to a low strain rate tensile test at −70°C, was studied by a combination of the focused-ion-beam method and transmission electron microscopy. An amorphous region with a chemical composition almost identical to that of the polycrystalline region was found under the lath-like structure on the fracture surface, although no deterioration of tensile properties by hydrogen appeared. In the amorphous region, band-like regions with wavy contrasts were observed, which were often accompanied by cracks at the boundaries. The presence of the amorphous region with band-like regions implies that amorphization occurred due to high-density vacancies accompanied by agglomerations of excess vacancies in the hydrogen-charged SUS 316L stainless steel that was tensile-tested at low temperatures
Surface electromyographic evaluation of the neuromuscular activation of the inspiratory muscles during progressively increased inspiratory flow under inspiratory-resistive loading
This study aimed to evaluate neuromuscular activation in the scalene and sternocleidomastoid muscles using surface electromyography (EMG) during progressively increased inspiratory flow, produced by increasing the respiratory rate under inspiratory-resistive loading using a mask ventilator. Moreover, we attempted to identify the EMG inflection point (EMGIP) on the graph, at which the root mean square (RMS) of the EMG signal values of the inspiratory muscles against the inspiratory flow velocity acceleration abruptly increases, similarly to the EMG anaerobic threshold (EMGAT) reported during incremental-resistive loading in other skeletal muscles. We measured neuromuscular activation of healthy male subjects and found that the inspiratory flow velocity increased by approximately 1.6-fold. We successfully observed an increase in RMS that corresponded to inspiratory flow acceleration with ρ ≥ 0.7 (Spearman’s rank correlation) in 17 of 27 subjects who completed the experimental protocol. To identify EMGIP, we analyzed the fitting to either a straight or non-straight line related to the increasing inspiratory flow and RMS using piecewise linear spline functions. As a result, EMGIP was identified in the scalene and sternocleidomastoid muscles of 17 subjects. We believe that the identification of EMGIP in this study infers the existence of EMGAT in inspiratory muscles. Application of surface EMG, followed by identification of EMGIP, for evaluating the neuromuscular activation of respiratory muscles may be allowed to estimate the signs of the respiratory failure, including labored respiration, objectively and non-invasively accompanied using accessory muscles in clinical respiratory care
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