A study of B-type stars

The effect of rotation on quantities used in classifying B -type stars is discussed. The tendency for stars with high rotational velocities to have weaker Balmer lines for the same (U - B)₀ has been investigated using published data. Abt's explanation of the affect in terms of the change in effective surface gravity due to rotation is confirmed. A correction term in Crawford's method of determining ages of clusters and field stars from Balmer line intensities and UBV photometry is derived. It is shown that errors in age determinations due to rotation are much smaller when the wavelength λ₁ of the Balmer discontinuity is used instead of Balmer line intensities. A colour index sensitive to λ₁ is discussed. Methods of determining the inclinations of the axes of rotation are suggested. It is shown that the "cosmic dispersion" in the relation between Balmer line intensities and absolute magnitudes is largely caused , by rotation. A scheme of two -dimensional spectral classification using measurements of the position and size of the Balmer discontinuity on low dispersion objective prism plates is outlined. Rotational velocities for 18 stars have been derived from slit spectrograms; several lines including five Balmer lines were measured for each star

Rotation and chemical composition of early-type stars

Some early-type stars with abnormal line strengths for their intrinsic colours are investigated in order to determine their structure and the chemical composition of their atmospheres. The abnormal line strengths in several B-type stars (αScl, 36 Lyn, 20 Tau and HD 175156) are shown to be probably due to large ranges of surface temperature such as would be observed in rapidly rotating stars of normal chemical composition, if viewed pole-on. These stars differ from the peculiar A stars, which rotate slowly and have abnormal chemical composition. Members of the Mn group of peculiar A stars rotate more slowly than those of the Si-4200 group, although the mean intrinsic colours of the two groups are similar.Previous work on abundance determination in peculiar A stars is reviewed. The chemical composition of the manganese star 53 Tau is studied by a refined differential curve-of-growth method with αLyr as the comparison star. Groups of lines of similar mean excitation and ionisation potentials and wavelengths are used so that the results are independent of the structure of 53 Tau, which is shown to be abnormal. A new double-line peculiar A spectroscopic binary HR 4072 was discovered, and it was found that excesses of Sr and Y are common to both components. Spectral variations in some peculiar A stars are described.Well established abundance abnormalities in peculiar A stars may be explained on a modified form of van den Heuvel's theory that peculiar A stars have been secondaries of binary systems with initial separations in the range 10 a.u. to 100 a.u. approximately. The primaries, initially earlier than spectral type B8, have evolved and exploded as type II supernovae. During the explosions material enriched in heavy elements by interior nuclear reactions was transferred to the surfaces of the secondaries, which are now observed as peculiar A stars and are still on the main sequence. Excesses of Be and Si and deficiencies of 0 are caused by surface nuclear reactions on the secondaries after the explosions of the primaries. Ln stars differ from other peculiar A stars in many respects; the differences may be due to the primaries expanding beyond the Roche limits before they explode. On the oblique rotator theory, spectrum variables result from irregular distributions of surface nuclear reactions and ion migration on the secondaries. Some other theories of peculiar A stars are reviewed and shown to be in conflict with observation

The influence of socioeconomic deprivation on multimorbidity at different ages: a cross-sectional study

<b>Background</b> Multimorbidity occurs at a younger age in individuals in areas of high socioeconomic deprivation but little is known about the 'typology' of multimorbidity in different age groups and its association with socioeconomic status.<p></p> <b>Aim</b> To characterise multimorbidity type and most common conditions in a large nationally representative primary care dataset in terms of age and deprivation.<p></p> <b>Design and setting</b> Cross-sectional analysis of 1 272 685 adults in Scotland.<p></p> <b>Method</b> Multimorbidity type of participants (physical-only, mental-only, mixed physical, and mental) and most common conditions were analysed according to age and deprivation.<p></p> <b>Results</b> Multimorbidity increased with age, ranging from 8.1% in those aged 25–34 to 76.1% for those aged ≥75 years. Physical-only (56% of all multimorbidity) was the most common type of multimorbidity in those aged ≥55 years, and did not vary substantially with deprivation. Mental-only was uncommon (4% of all multimorbidity), whereas mixed physical and mental (40% of all multimorbidity) was the most common type of multimorbidity in those aged <55 years and was two- to threefold more common in the most deprived compared with the least deprived in most age groups. Ten conditions (seven physical and three mental) accounted for the top five most common conditions in people with multimorbidity in all age groups. Depression and pain featured in the top five conditions across all age groups. Deprivation was associated with a higher prevalence of depression, drugs misuse, anxiety, dyspepsia, pain, coronary heart disease, and diabetes in multimorbid patients at different ages.<p></p> <b>Conclusion</b> Mixed physical and mental multimorbidity is common across the life-span and is exacerbated by deprivation from early adulthood onwards

Heterotopic Ossification following Suprapatellar Intramedullary Nailing.

Introduction: Tibial shaft fractures are common fractures seen in trauma and orthopedic practice today. The majority of these fractures are treated with intramedullary nailing (IMN) which is rapidly becoming a gold standard. The procedure itself is performed by either a suprapatellar approach or infrapatellar approach. Suprapatellar approach is gaining popularity due to relative ease of insertion, decreased associated risk of anterior knee pain, and more accurate reduction. We report a case of heterotopic ossification noted in the knee following IMN of tibia performed using a suprapatellar approach. Case Report: A 27-year-old male, having sustained a left, Gustilo IIIB tibial shaft fracture following a motor vehicle accident, underwent a reamed intramedullary nail fixation performed through a suprapatellar approach. Two months later, he presented with intra-articular heterotopic ossification which was limiting his knee movement. He then underwent arthroscopic removal of the bony fragments which resolved his symptoms. Conclusion: An extensive search of literature did not yield any reported incidence of heterotopic ossification associated with IMN performed through a suprapatellar approach. We present this case report to raise awareness that although IMN through a suprapatellar approach is a safe approach, it does have associated risk of heterotopic ossification which needs to be included in the consent process

Modelling the atomic structure of very high-density amorphous ice

The structure of very high-density amorphous (VHDA) ice has been modelled by positionally disordering three crystalline phases, namely ice IV, VI and XII. These phases were chosen because only they are stable or metastable in the region of the ice phase diagram where VHDA ice is formed, and their densities are comparable to that of VHDA ice. An excellent fit to the medium range of the experimentally observed pair-correlation function g(r) of VHDA ice was obtained by introducing disorder into the positions of the H2O molecules, as well as small amounts of molecular rotational disorder, disorder in the O--H bond lengths and disorder in the H--O--H bond angles. The low-k behaviour of the experimental structure factor, S(k), is also very well reproduced by this disordered-crystal model. The fraction of each phase present in the best-fit disordered model is very close to that observed in the probable crystallization products of VHDA ice. In particular, only negligible amounts of ice IV are predicted, in accordance with experimental observation.Comment: 4 pages, 3 figures, 1 table, v2: changes made in response to referees' comments, the justification for using certain ice phases is improved, and ice IV is now disordered as wel

The disastrous 17 February 2006 rockslide-debris avalanche on Leyte Island, Philippines: a catastrophic landslide in tropical mountain terrain

International audienceIn February 2006, a disastrous rockslide-debris avalanche occurred in tropical mountain terrain, on Leyte Island, Central Philippines. Over 1100 people perished when the village of Guinsaugon was overwhelmed directly in the path of the landslide. The landslide was initiated by the failure of a 450 m high rock slope within the damage zone of the Philippine Fault where the rock mass consisted of sheared and brecciated volcanic, sedimentary and volcaniclastic rocks. Tectonic weakening of the failed rock mass had resulted from active strike-slip movements along the Philippine Fault which have been estimated by other workers at 2.5 cm/year. The landslide involved a total volume of 15 Mm3, including significant entrainment from its path, and ran out a horizontal distance of 3800 m over a vertical distance of 810 m, equivalent to a fahrböschung of 12°. Run-out distance was enhanced by friction reduction due to undrained loading when the debris encountered flooded paddy fields in the valley bottom at a path distance of 2600 m. A simulation of the event using the dynamic analysis model DAN indicated a mean velocity of 35 m/s and demonstrated the contribution of the paddy field effect to total run-out distance. There was no direct trigger for the landslide but the landslide did follow a period of very heavy rainfall with a lag time of four days. The rockslide-debris avalanche is one of several disastrous landslides to have occurred in the Philippines in the last twenty years. In terms of loss of life, the Guinsaugon event is the most devastating single-event landslide to have occurred worldwide since the Casita Volcano rock avalanche-debris flow which was triggered by Hurricane Mitch in Nicaragua in 1998

Surviving Communicative Labor: Theoretical Exploration of the (In)Visibility of Gendered Faculty Work/Life Struggle

The work experiences of faculty in higher education often entail being overworked and stressed, and this is particularly true for women faculty and faculty of color. This essay is situated at the intersection of gender, race, axiological, epistemological, and occupational identities. In this metatheoretical argument, we propose a new concept communicative labor by exploring how existing scholarly frameworks regarding workplace emotion, compassionate communication, and gendered work intersect to inform the experiences of critical women scholars and the ways their labor is communicatively manifested across research, teaching, and service. More specifically, we argue that communication itself (i.e., literally listening, speaking, and writing) becomes emotionally-laden work amid the research, teaching, and service performed by critical women scholars. We aim, through our articulation of communication labor, to disrupt dominant narratives of what faculty work lives should be, and we call for a paradigm shift in the way faculty labor is socially constructed so that we can improve critical women faculty’s success and well-being

Chain Galaxies are Edge-On Low Surface Brightness Galaxies

Deep HST WFPC2 images have revealed a population of very narrow blue galaxies which Cowie et al. (1996) have interpreted as being a new morphological class of intrinsically linear star forming galaxies at $z=0.5-3$. We show that the same population exists in large numbers at low redshifts (z=0.03) and are actually the edge-on manifestation of low surface brightness disk galaxies.Comment: 18 pages + 3 pages of figures. Uuencoded, gzipped, tar file of 1 latex file, 5 figures, and 2 latex style files. To appear in the Astrophysical Journal Letter

Effective Feedback to Improve Primary Care Prescribing Safety (EFIPPS) a pragmatic three-arm cluster randomised trial:designing the intervention (ClinicalTrials.gov registration NCT01602705)

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