996 resultados para Stars: individual (sigma Ori)
Resumo:
Context. Rotational mixing in massive stars is a widely applied concept, with far-reaching consequences for stellar evolution, nucleosynthesis, and stellar explosions.
Resumo:
Advances in surgical procedure, prosthesis design, and biomaterials performance have considerably increased the longevity of total joint replacements. Preoperative planning is another step in joint replacement that may have the potential to improve clinical outcome for the individual patient, but has remained relatively consistent for a longtime. One means of advancing this aspect of joint replacement surgery may be to include predictive computer simulation into the planning process. In this article, the potential of patient-specific finite element analysis in preoperative assessment is investigated. Seventeen patient-specific finite element models of cemented Charnley reconstructions were created, of which six were early (
Resumo:
In this paper I examine the scope of publicly available information on the religious composition of employees in private-sector companies in Northern Ireland. I highlight the unavailability of certain types of monitoring data and the impact of data aggregation at company as opposed to site level. Both oversights lead to underestimates of the extent of workplace segregation in Northern Ireland. The ability to provide more-coherent data on workplace segregation, by religion, in Northern Ireland is crucial in terms of advancing equality and other social-justice agendas. I argue that a more-accurate monitoring of religious composition of workplaces is part of an overall need to develop a spatial approach in which the importance of ethnically territorialised spaces in the reproduction of ethnosectarian disputation is understood.
Resumo:
We present near- (NIR) and mid-infrared (MIR) photometric data of the Type Ibn supernova (SN) 2006jc obtained with the United Kingdom Infrared Telescope (UKIRT), the Gemini North Telescope and the Spitzer Space Telescope between days 86 and 493 post-explosion. We find that the IR behaviour of SN 2006jc can be explained as a combination of IR echoes from two manifestations of circumstellar material. The bulk of the NIR emission arises from an IR echo from newly condensed dust in a cool dense shell (CDs) produced by the interaction of the ejecta Outward shock with a dense shell of circumstellar material ejected by the progenitor in a luminous blue variable (LBV)-like outburst about two years prior to the SN explosion. The CDs dust mass reaches a modest 3.0 x 10(-4) M-circle dot by day 230. While dust condensation within a CDs formed behind the ejecta inward shock has been proposed before for one event (SN 1998S), SN 2006jc is the first one showing evidence for dust condensation in a CDs formed behind the ejecta outward shock in the circumstellar material. At later epochs, a substantial and growing contribution to the IR fluxes arises from an IR echo from pre-existing dust in the progenitor wind. The mass of the pre-existing circumstellar medium (CSM) dust is at least similar to 8 x 10(-3) M-circle dot. This paper therefore adds to the evidence that mass-loss from the progenitors of core-collapse SNe could be a major source of dust in the Universe. However, yet again, we see no direct evidence that the explosion of an SN produces anything other than a very modest amount of dust.
Resumo:
The stars 51 Pegasi and tau Bootis show radial velocity variations that have been interpreted as resulting from companions with roughly Jovian mass and orbital periods of a few days. Gray and Gray & Hatzes reported that the radial velocity signal of 51 Peg is synchronous with variations in the shape of the line lambda 6253 Fe I; thus, they argue that the velocity signal arises not from a companion of planetary mass but from dynamic processes in the atmosphere of the star, possibly nonradial pulsations. Here we seek confirming evidence for line shape or strength variations in both 51 Peg and tau Boo, using R = 50,000 observations taken with the Advanced Fiber Optic Echelle. Because of our relatively low spectral resolution, we compare our observations with Gray's line bisector data by fitting observed line profiles to an expansion in terms of orthogonal (Hermite) functions. To obtain an accurate comparison, we model the emergent line profiles from rotating and pulsating stars, taking the instrumental point-spread function into account. We describe this modeling process in detail. We find no evidence for line profile or strength variations at the radial velocity period in either 51 Peg or in tau Boo. For 51 Peg, our upper limit for line shape variations with 4.23 day periodicity is small enough to exclude with 10 sigma confidence the bisector curvature signal reported by Gray & Hatzes; the bisector span and relative line depth signals reported by Gray are also not seen, but in this case with marginal (2 sigma ) confidence. We cannot, however, exclude pulsations as the source of 51 Peg's radial velocity variation because our models imply that line shape variations associated with pulsations should be much smaller than those computed by Gray & Hatzes; these smaller signals are below the detection limits both for Gray & Hatzes's data and for our own. tau Boo's large radial velocity amplitude and v sin i make it easier to test for pulsations in this star. Again we find no evidence for periodic line shape changes, at a level that rules out pulsations as the source of the radial velocity variability. We conclude that the planet hypothesis remains the most likely explanation for the existing data.
Resumo:
Using a large-scale data set, this article considers the role and growing importance of the Rights Commissioners in Ireland. The Rights Commissioners’ service, which has no parallel in any other anglophone industrial relations system, provides an informal and accessible method for the resolution of disputes and the vindication of employment rights. In recent years, the number of cases handled by the Rights Commissioners has grown hugely. A close examination of the cases handled by the service suggests that the Rights Commissioners allow vulnerable workers to pursue cases of alleged breaches of employment rights. The service is seen as holding lessons for other economies in terms of developing a model of economic citizenship that has as a dimension the enforcement of employment rights.
Resumo:
Migrating bats are among the most poorly understood of migratory taxa, with relatively little information available on their behavior and ecology during migration compared to other taxa. This arises because of the
Resumo:
The purpose of our two-year follow-up study was to examine the effect of the social components of the work group, such as group absence norms and cohesion, on sickness absence behavior among individuals with varying attitudes toward work attendance. The social components were measured using a questionnaire survey, and data on sickness absence behavior were collected from the employers' records. The study population consisted of 19,306 Finnish municipal employees working in 1,847 groups (78% women). Multilevel Poisson regression modeling was applied. The direct effects of work group characteristics on sickness absence were mostly insignificant. In contrast, both of the social components of a work group had an indirect impact: The more tolerant the group absence norms (at both individual- and cross-level) and the lower the group cohesion (at the individual level), the more the absence behavior of an individual was influenced by his or her attitude toward work attendance. We conclude that work group moderates the extent to which individuals with a liberal attitude toward work attendance actually engage in sickness absence behavior.
Resumo:
We have studied over 1600 Am stars at a photometric precision of 1 mmag with SuperWASP photometric data. Contrary to previous belief, we find that around 200 Am stars are pulsating d Sct and ? Dor stars, with low amplitudes that have been missed in previous, less extensive studies. While the amplitudes are generally low, the presence of pulsation in Am stars places a strong constraint on atmospheric convection, and may require the pulsation to be laminar. While some pulsating Am stars have been previously found to be d Sct stars, the vast majority of Am stars known to pulsate are presented in this paper. They will form the basis of future statistical studies of pulsation in the presence of atomic diffusion. An extended version of Table 1 containing all the detected frequencies and amplitudes is only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/535/A3
Resumo:
Heat Alert and Response Systems (HARS) are currently undergoing testing and implementation in Canada. These programs seek to reduce the adverse health effects of heat waves on human health by issuing weather forecasts and warnings, informing individuals about possible protections from excessive heat, and providing such protections to vulnerable subpopulations and individuals at risk. For these programs to be designed effectively, it is important to know how individuals perceive the heat, what their experience with heat-related illness is, how they protect themselves from excessive heat, and how they acquire information about such protections. In September 2010, we conducted a survey of households in 5 cities in Canada to study these issues. At the time of the survey, these cities had not implemented heat outreach and response systems. The study results indicate that individuals' recollections of recent heat wave events were generally accurate. About 21% of the sample reported feeling unwell during the most recent heat spell, but these illnesses were generally minor. Only in 25 cases out of 243, these illnesses were confirmed or diagnosed by a health care professional. The rate at which our respondents reported heat-related illnesses was higher among those with cardiovascular and respiratory illnesses, was higher among younger respondents and bore no relationship with the availability of air conditioning at home. Most of the respondents indicated that they would not dismiss themselves as