262 research outputs found

    The evolution of rotating stars

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    First, we review the main physical effects to be considered in the building of evolutionary models of rotating stars on the Upper Main-Sequence (MS). The internal rotation law evolves as a result of contraction and expansion, meridional circulation, diffusion processes and mass loss. In turn, differential rotation and mixing exert a feedback on circulation and diffusion, so that a consistent treatment is necessary. We review recent results on the evolution of internal rotation and the surface rotational velocities for stars on the Upper MS, for red giants, supergiants and W-R stars. A fast rotation is enhancing the mass loss by stellar winds and reciprocally high mass loss is removing a lot of angular momentum. The problem of the ``break-up'' or Ω\Omega-limit is critically examined in connection with the origin of Be and LBV stars. The effects of rotation on the tracks in the HR diagram, the lifetimes, the isochrones, the blue to red supergiant ratios, the formation of W-R stars, the chemical abundances in massive stars as well as in red giants and AGB stars, are reviewed in relation to recent observations for stars in the Galaxy and Magellanic Clouds. The effects of rotation on the final stages and on the chemical yields are examined, as well as the constraints placed by the periods of pulsars. On the whole, this review points out that stellar evolution is not only a function of mass M and metallicity Z, but of angular velocity Ω\Omega as well.Comment: 78 pages, 7 figures, review for Annual Review of Astronomy and Astrophysics, vol. 38 (2000

    Responsiveness of multiple patient-reported outcome measures for acute postsurgical pain: primary results from the international multi-centre PROMPT NIT-1 study

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    This is the final version. Available on open access from Elsevier via the DOI in this recordBACKGROUND: Postsurgical outcome measures are crucial to define the efficacy of perioperative pain management; however, it is unclear which are most appropriate. We conducted a prospective study aiming to assess sensitivity-to-change of patient-reported outcome measures assessing the core outcome set of domains pain intensity (at rest/during activity), physical function, adverse events, and self-efficacy. METHODS: Patient-reported outcome measures were assessed preoperatively, on day 1 (d1), d3, and d7 after four surgical procedures (total knee replacement, breast surgery, endometriosis-related surgery, and sternotomy). Primary outcomes were sensitivity-to-change of patient-reported outcome measures analysed by correlating their changes (d1-d3) with patients' global impression of change and patients' specific impression of change items as anchor criteria. Secondary outcomes included identification of baseline and patient characteristic variables explaining variance in change for each of the scales and descriptive analysis of various patient-reported outcome measures from different domains and after different surgeries. RESULTS: Of 3322 patients included (18 hospitals, 10 countries), data from 2661 patients were analysed. All patient-reported outcome measures improved on average over time; the median calculated sensitivity-to-change for all patient-reported outcome measures (overall surgeries) was 0.22 (range: 0.07-0.31, scale: 0-10); all changes were independent of baseline data or patient characteristics and similar between different procedures. CONCLUSIONS: Pain-related patient-reported outcome measures have low to moderate sensitivity-to-change; those showing higher sensitivity-to-change from the same domain should be considered for inclusion in a core outcome set of patient-reported outcome measures to assess the effectiveness and efficacy of perioperative pain management.European Union Horizon 2020EFPIA Companie

    The quest for the solar g modes

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    Solar gravity modes (or g modes) -- oscillations of the solar interior for which buoyancy acts as the restoring force -- have the potential to provide unprecedented inference on the structure and dynamics of the solar core, inference that is not possible with the well observed acoustic modes (or p modes). The high amplitude of the g-mode eigenfunctions in the core and the evanesence of the modes in the convection zone make the modes particularly sensitive to the physical and dynamical conditions in the core. Owing to the existence of the convection zone, the g modes have very low amplitudes at photospheric levels, which makes the modes extremely hard to detect. In this paper, we review the current state of play regarding attempts to detect g modes. We review the theory of g modes, including theoretical estimation of the g-mode frequencies, amplitudes and damping rates. Then we go on to discuss the techniques that have been used to try to detect g modes. We review results in the literature, and finish by looking to the future, and the potential advances that can be made -- from both data and data-analysis perspectives -- to give unambiguous detections of individual g modes. The review ends by concluding that, at the time of writing, there is indeed a consensus amongst the authors that there is currently no undisputed detection of solar g modes.Comment: 71 pages, 18 figures, accepted by Astronomy and Astrophysics Revie

    Women’s responses to changes in U.S. preventive task force’s mammography screening guidelines: results of focus groups with ethnically diverse women

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    Background: The 2009 U.S. Preventive Services Task Force (USPSTF) changed mammography guidelines to recommend routine biennial screening starting at age 50. This study describes women’s awareness of, attitudes toward, and intention to comply with these new guidelines. Methods: Women ages 40–50 years old were recruited from the Boston area to participate in focus groups (k = 8; n = 77). Groups were segmented by race/ethnicity (Caucasian = 39%; African American = 35%; Latina = 26%), audio-taped, and transcribed. Thematic content analysis was used. Results: Participants were largely unaware of the revised guidelines and suspicious that it was a cost-savings measure by insurers and/or providers. Most did not intend to comply with the change, viewing screening as obligatory. Few felt prepared to participate in shared decision-making or advocate for their preferences with respect to screening. Conclusions: Communication about the rationale for mammography guideline changes has left many women unconvinced about potential disadvantages or limitations of screening. Since further guideline changes are likely to occur with advances in technology and science, it is important to help women become informed consumers of health information and active participants in shared decision-making with providers. Additional research is needed to determine the impact of the USPSTF change on women’s screening behaviors and on breast cancer outcomes

    Resistance Exercise Reverses Aging in Human Skeletal Muscle

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    Human aging is associated with skeletal muscle atrophy and functional impairment (sarcopenia). Multiple lines of evidence suggest that mitochondrial dysfunction is a major contributor to sarcopenia. We evaluated whether healthy aging was associated with a transcriptional profile reflecting mitochondrial impairment and whether resistance exercise could reverse this signature to that approximating a younger physiological age. Skeletal muscle biopsies from healthy older (N = 25) and younger (N = 26) adult men and women were compared using gene expression profiling, and a subset of these were related to measurements of muscle strength. 14 of the older adults had muscle samples taken before and after a six-month resistance exercise-training program. Before exercise training, older adults were 59% weaker than younger, but after six months of training in older adults, strength improved significantly (P<0.001) such that they were only 38% lower than young adults. As a consequence of age, we found 596 genes differentially expressed using a false discovery rate cut-off of 5%. Prior to the exercise training, the transcriptome profile showed a dramatic enrichment of genes associated with mitochondrial function with age. However, following exercise training the transcriptional signature of aging was markedly reversed back to that of younger levels for most genes that were affected by both age and exercise. We conclude that healthy older adults show evidence of mitochondrial impairment and muscle weakness, but that this can be partially reversed at the phenotypic level, and substantially reversed at the transcriptome level, following six months of resistance exercise training

    Diseases and Causes of Death in European Bats: Dynamics in Disease Susceptibility and Infection Rates

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    Bats receive increasing attention in infectious disease studies, because of their well recognized status as reservoir species for various infectious agents. This is even more important, as bats with their capability of long distance dispersal and complex social structures are unique in the way microbes could be spread by these mammalian species. Nevertheless, infection studies in bats are predominantly limited to the identification of specific pathogens presenting a potential health threat to humans. But the impact of infectious agents on the individual host and their importance on bat mortality is largely unknown and has been neglected in most studies published to date.) were collected in different geographic regions in Germany. Most animals represented individual cases that have been incidentally found close to roosting sites or near human habitation in urban and urban-like environments. The bat carcasses were subjected to a post-mortem examination and investigated histo-pathologically, bacteriologically and virologically. Trauma and disease represented the most important causes of death in these bats. Comparative analysis of pathological findings and microbiological results show that microbial agents indeed have an impact on bats succumbing to infectious diseases, with fatal bacterial, viral and parasitic infections found in at least 12% of the bats investigated.Our data demonstrate the importance of diseases and infectious agents as cause of death in European bat species. The clear seasonal and individual variations in disease prevalence and infection rates indicate that maternity colonies are more susceptible to infectious agents, underlining the possible important role of host physiology, immunity and roosting behavior as risk factors for infection of bats

    Meta-Profiles of Gene Expression during Aging: Limited Similarities between Mouse and Human and an Unexpectedly Decreased Inflammatory Signature

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    Background: Skin aging is associated with intrinsic processes that compromise the structure of the extracellular matrix while promoting loss of functional and regenerative capacity. These processes are accompanied by a large-scale shift in gene expression, but underlying mechanisms are not understood and conservation of these mechanisms between humans and mice is uncertain. Results: We used genome-wide expression profiling to investigate the aging skin transcriptome. In humans, age-related shifts in gene expression were sex-specific. In females, aging increased expression of transcripts associated with T-cells, B-cells and dendritic cells, and decreased expression of genes in regions with elevated Zeb1, AP-2 and YY1 motif density. In males, however, these effects were contrasting or absent. When age-associated gene expression patterns in human skin were compared to those in tail skin from CB6F1 mice, overall human-mouse correspondence was weak. Moreover, inflammatory gene expression patterns were not induced with aging of mouse tail skin, and well-known aging biomarkers were in fact decreased (e.g., Clec7a, Lyz1 and Lyz2). These unexpected patterns and weak human-mouse correspondence may be due to decreased abundance of antigen presenting cells in mouse tail skin with age. Conclusions: Aging is generally associated with a pro-inflammatory state, but we have identified an exception to this pattern with aging of CB6F1 mouse tail skin. Aging therefore does not uniformly heighten inflammatory status across all mouse tissues. Furthermore, we identified both intercellular and intracellular mechanisms of transcriptome aging, including those that are sex- and species-specific
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