1,927 research outputs found
Recommended Atomic Data for Collisional Radiative Model of Li-like Ions and Gain Calculation for Li-like Al Plasmas
Hydrodynamic Interaction between the Be Star and the Pulsar in the TeV Binary PSR B1259-63/LS 2883
We study the interaction between the Be star and the pulsar in the TeV binary
PSR B1259-63/LS 2883, using 3-D SPH simulations of the tidal and wind
interactions in this Be-pulsar system. We first run a simulation without pulsar
wind nor Be wind, taking into account only the gravitational effect of the
pulsar on the Be disk. In this simulation, the gas particles are ejected at a
constant rate from the equatorial surface of the Be star, which is tilted in a
direction consistent with multi-waveband observations. We run the simulation
until the Be disk is fully developed and starts to repeat a regular tidal
interaction with the pulsar. Then, we turn on the pulsar wind and the Be wind.
We run two simulations with different wind mass-loss rates for the Be star, one
for a B2V type and the other for a significantly earlier spectral type.
Although the global shape of the interaction surface between the pulsar wind
and the Be wind agrees with the analytical solution, the effect of the pulsar
wind on the Be disk is profound. The pulsar wind strips off an outer part of
the Be disk, truncating the disk at a radius significantly smaller than the
pulsar orbit. Our results, therefore, rule out the idea that the pulsar passes
through the Be disk around periastron, which has been assumed in the previous
studies. It also turns out that the location of the contact discontinuity can
be significantly different between phases when the pulsar wind directly hits
the Be disk and those when the pulsar wind collides with the Be wind. It is
thus important to adequately take into account the circumstellar environment of
the Be star, in order to construct a satisfactory model for this prototypical
TeV binary.Comment: 10 pages, 5 figures, accepted for publication in PAS
Radio Frequency Electrical Resistance Measurement under Destructive Pulsed Magnetic Fields
We developed a resistance measurement using radio frequency reflection to
investigate the electrical transport characteristics under destructive pulsed
magnetic fields above 100 T. A homemade flexible printed circuit for a sample
stage reduced the noise caused by the induced voltage from the pulsed magnetic
fields, improving the accuracy of the measurements of the reflected waves. From
the obtained reflectance data, the absolute value of the magnetoresistance was
successfully determined by using a phase analysis with admittance charts. These
developments enable more accurate and comprehensive measurements of electrical
resistance in pulsed magnetic fields.Comment: 7 pages, 5 figure
Modeling high-energy light curves of the PSR B1259-63/LS 2883 binary based on 3-D SPH simulations
Temporal changes of X-ray to very-high-energy gamma-ray emissions from the
pulsar-Be star binary PSR B1259-63/LS 2883 are studied based on 3-D SPH
simulations of pulsar wind interaction with Be-disk and wind. We focus on the
periastron passage of the binary and calculate the variation of the synchrotron
and inverse-Compton emissions using the simulated shock geometry and pressure
distribution of the pulsar wind. The characteristic double-peaked X-ray light
curve from observations is reproduced by our simulation under a dense Be disk
condition (base density ~10^{-9} g cm^{-3}). We interpret the pre- and
post-periastron peaks as being due to a significant increase in the conversion
efficiency from pulsar spin down power to the shock-accelerated particle energy
at orbital phases when the pulsar crosses the disk before periastron passage,
and when the pulsar wind creates a cavity in the disk gas after periastron
passage, respectively. On the contrary, in the model TeV light curve, which
also shows a double peak feature, the first peak appears around the periastron
phase. The possible effects of cooling processes on the TeV light curve are
briefly discussed.Comment: 32 pages, 6 figues. Accepted for publication in Ap
Neighborhood social capital is associated with participation in health checks of a general population: a multilevel analysis of a population-based lifestyle intervention- the Inter99 study
Multi-level, cross-sectional study of workplace social capital and smoking among Japanese employees
<p>Abstract</p> <p>Background</p> <p>Social capital is hypothesized to be relevant to health promotion, and the association between community social capital and cigarette smoking has been examined. Individual-level social capital has been found to be associated with smoking cessation, but evidence remains sparse on the contextual effect of social capital and smoking. Further, evidence remains sparse on the association between smoking and social capital in the workplace, where people are spending an increasing portion of their daily lives. We examined the association between workplace social capital and smoking status among Japanese private sector employees.</p> <p>Methods</p> <p>We employed a two-stage stratified random sampling procedure. Of the total of 1,800 subjects in 60 companies, 1,171 (men/women; 834/337) employees (65.1%) were identified from 46 companies in Okayama in 2007. Workplace social capital was assessed in two dimensions; trust and reciprocity. Company-level social capital was based on inquiring about employee perceptions of trust and reciprocity among co-workers, and then aggregating their responses in order to calculate the proportion of workers reporting mistrust and lack of reciprocity. Multilevel logistic regression analysis was conducted using Markov Chain Monte Carlo methods to explore whether individual- and company-level social capital was associated with smoking. Odds ratios (ORs) and 95% credible intervals (CIs) for current smoking were obtained.</p> <p>Results</p> <p>Overall, 33.3% of the subjects smoked currently. There was no relationship between individual-level mistrust of others and smoking status. By contrast, one-standard deviation change in company-level mistrust was associated with higher odds of smoking (OR: 1.25, 95% CI: 1.06-1.46) even after controlling for individual-level mistrust, sex, age, occupation, educational attainment, alcohol use, physical activity, body mass index, and chronic diseases. No clear associations were found between lack of reciprocity and smoking both at the individual- and company-level.</p> <p>Conclusions</p> <p>Company-level mistrust is associated with higher likelihood of smoking among Japanese employees, while individual perceptions of mistrust were not associated. The link between lack of reciprocity and smoking was not supported either at the individual- or company-level. Further studies are warranted to examine the possible link between company-level trust and smoking cessation in the Japanese workplace.</p
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