525 research outputs found

    Rotation and activity of pre-main-sequence stars

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    We present a study of rotation (vsini) and chromospheric activity (Halpha EW) based on an extensive set of high-resolution optical spectra obtained with MIKE on the 6.5m Magellan Clay telescope. Our targets are 74 F-M dwarfs in the young stellar associations Eta Cha, TW Hydrae, Beta Pic, and Tuc-Hor, spanning ages from 6 to 30 Myr. While the Halpha EW for most F and G stars are consistent with pure photospheric absorption, most K and M stars show chromospheric emission. By comparing Halpha EW in our sample to results in the literature, we see a clear evolutionary sequence: Chromospheric activity declines steadily from the T Tauri phase to the main sequence. Using activity as an age indicator, we find a plausible age range for the Tuc-Hor association of 10-40 Myr. Between 5 and 30 Myr, we do not see evidence for rotational braking in the total sample, thus angular momentum is conserved, in contrast to younger stars. This difference indicates a change in the rotational regulation at 5-10 Myr, possibly because disk braking cannot operate longer than typical disk lifetimes, allowing the objects to spin up. The rotation-activity relation is flat in our sample; in contrast to main-sequence stars, there is no linear correlation for slow rotators. We argue that this is because young stars generate their magnetic fields in a fundamentally different way from main-sequence stars, and not just the result of a saturated solar-type dynamo. By comparing our rotational velocities with published rotation periods for a subset of stars, we determine ages of 13 (7-20) Myr and 9 (7-17} Myr for the Eta Cha and TWA associations, respectively, consistent with previous estimates. Thus we conclude that stellar radii from evolutionary models by Baraffe et al. (1998) are in agreement with the observed radii within +-15%. (abridged)Comment: 40 pages, 8 figures, ApJ, in pres

    Milk lipid globules: control of their size distribution.

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    Measuring thermal performance in steady-state conditions at each stage of a full fabric retrofit to a solid wall dwelling

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    The methodology used for measuring the thermal performance of fabric retrofit systems which were applied to a solid wall UK Victorian house situated within an environmental chamber is explored in detail. The work describes how steady-state boundary conditions were approximated, then repeated at the Salford Energy House test facility. How established methods of measuring the fabric thermal performance of buildings in situ were adapted to test the effectiveness of retrofit measures within a steady-state environment. The results presented show that steady-state boundary conditions enable the change in fabric heat loss resulting from the retrofit of a whole house or individual element to be measured to a level of accuracy and precision that is unlikely to be achieved in the field. The test environment enabled identification of heat loss phenomena difficult to detect in the field. However, undertaking tests in an environment devoid of wind underestimates the potential reduction in ventilation heat loss resulting from an improvement in airtightness, and hides the susceptibility of retrofit measures to various heat loss mechanisms, such as wind washing. The strengths and weaknesses of the methods employed, the Energy House test facility, and a steady-state environment, for characterising retrofit building fabric thermal performance are demonstrated

    Prognosis research strategy (PROGRESS) 1: a framework for researching clinical outcomes.

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    The PROGRESS series (www.progress-partnership.org) sets out a framework of four interlinked prognosis research themes and provides examples from several disease fields to show why evidence from prognosis research is crucial to inform all points in the translation of biomedical and health related research into better patient outcomes. Recommendations are made in each of the four papers to improve current research standards What is prognosis research? Prognosis research seeks to understand and improve future outcomes in people with a given disease or health condition. However, there is increasing evidence that prognosis research standards need to be improved Why is prognosis research important? More people now live with disease and conditions that impair health than at any other time in history; prognosis research provides crucial evidence for translating findings from the laboratory to humans, and from clinical research to clinical practice This first article introduces the framework of four interlinked prognosis research themes and then focuses on the first of the themes - fundamental prognosis research, studies that aim to describe and explain future outcomes in relation to current diagnostic and treatment practices, often in relation to quality of care Fundamental prognosis research provides evidence informing healthcare and public health policy, the design and interpretation of randomised trials, and the impact of diagnostic tests on future outcome. It can inform new definitions of disease, may identify unanticipated benefits or harms of interventions, and clarify where new interventions are required to improve prognosis

    Long-term improvements following a residential combined physical and psychological programme for chronic low back pain

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    Objectives Evaluate the outcomes and explore experiences of patients undergoing a residential combined physical and psychological programme (CPPP) for chronic low back pain. Design A longitudinal observational cohort design, with a parallel qualitative design using semistructured interviews. Setting Residential, multimodal rehabilitation. Participants 136 adults (62 male/74 female) referred to the CPPP, 100 (44 male/56 female) of whom completed the programme, during the term of the study. Ten (2 male/8 female) participated in the qualitative evaluation. Intervention A 3-week residential CPPP. Outcome measures Primary outcome measures were the STarT Back screening tool score; pain intensity-11-point Numerical Rating Scale; function-Oswestry Disability Index (ODI); health status/quality of life-EQ-5D-5L EuroQol five-Dimension-five level; anxiety-Generalised Anxiety Disorder-7; depression-Patient Health Questionnaire-9. Secondary outcome measures were the Global Subjective Outcome Scale; National Health Service Friends and Family Test;. Results At discharge, 6 and 12 months follow ups, there were improvements from baseline that were greater than minimum clinically important differences in each of the outcomes (with the sole exception of ODI at discharge). At 12 months, the majority of people considered themselves a lot better (57%) and were extremely likely (86%) to recommend the programme to a friend. The qualitative data showed praise for the residential nature of the intervention and the opportunities for interaction with peers and peer support. There were testimonies of improvements in understanding of pain and how to manage it better. Some participants said they had reduced, or stopped, medication they had been taking to manage their pain. Conclusions Participants improved, and maintained long term, beyond minimum clinically important differences on a wide range of outcomes. Participants reported an enhanced ability to self-manage their back pain and support for the residential setting

    The discovery of potent, selective, and reversible inhibitors of the house dust mite peptidase allergen Der p 1: an innovative approach to the treatment of allergic asthma.

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    Blocking the bioactivity of allergens is conceptually attractive as a small-molecule therapy for allergic diseases but has not been attempted previously. Group 1 allergens of house dust mites (HDM) are meaningful targets in this quest because they are globally prevalent and clinically important triggers of allergic asthma. Group 1 HDM allergens are cysteine peptidases whose proteolytic activity triggers essential steps in the allergy cascade. Using the HDM allergen Der p 1 as an archetype for structure-based drug discovery, we have identified a series of novel, reversible inhibitors. Potency and selectivity were manipulated by optimizing drug interactions with enzyme binding pockets, while variation of terminal groups conferred the physicochemical and pharmacokinetic attributes required for inhaled delivery. Studies in animals challenged with the gamut of HDM allergens showed an attenuation of allergic responses by targeting just a single component, namely, Der p 1. Our findings suggest that these inhibitors may be used as novel therapies for allergic asthma

    Darkness visible: reflections on underground ecology

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    1 Soil science and ecology have developed independently, making it difficult for ecologists to contribute to urgent current debates on the destruction of the global soil resource and its key role in the global carbon cycle. Soils are believed to be exceptionally biodiverse parts of ecosystems, a view confirmed by recent data from the UK Soil Biodiversity Programme at Sourhope, Scotland, where high diversity was a characteristic of small organisms, but not of larger ones. Explaining this difference requires knowledge that we currently lack about the basic biology and biogeography of micro-organisms. 2 It seems inherently plausible that the high levels of biological diversity in soil play some part in determining the ability of soils to undertake ecosystem-level processes, such as carbon and mineral cycling. However, we lack conceptual models to address this issue, and debate about the role of biodiversity in ecosystem processes has centred around the concept of functional redundancy, and has consequently been largely semantic. More precise construction of our experimental questions is needed to advance understanding. 3 These issues are well illustrated by the fungi that form arbuscular mycorrhizas, the Glomeromycota. This ancient symbiosis of plants and fungi is responsible for phosphate uptake in most land plants, and the phylum is generally held to be species-poor and non-specific, with most members readily colonizing any plant species. Molecular techniques have shown both those assumptions to be unsafe, raising questions about what factors have promoted diversification in these fungi. One source of this genetic diversity may be functional diversity. 4 Specificity of the mycorrhizal interaction between plants and fungi would have important ecosystem consequences. One example would be in the control of invasiveness in introduced plant species: surprisingly, naturalized plant species in Britain are disproportionately from mycorrhizal families, suggesting that these fungi may play a role in assisting invasion. 5 What emerges from an attempt to relate biodiversity and ecosystem processes in soil is our extraordinary ignorance about the organisms involved. There are fundamental questions that are now answerable with new techniques and sufficient will, such as how biodiverse are natural soils? Do microbes have biogeography? Are there rare or even endangered microbes

    The Legacy of Hope Summit: A Consensus-Based Initiative and Report on Eating Disorders in the U.S. and Recommendations for the Path Forward

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    Background: Several unsuccessful attempts have been made to reach a cross-disciplinary consensus on issues fundamental to the field of eating disorders in the United States (U.S.). In January 2020, 25 prominent clinicians, academicians, researchers, persons with lived experience, and thought leaders in the U.S. eating disorders community gathered at the Legacy of Hope Summit to try again. This paper articulates the points on which they reached a consensus. It also: (1) outlines strategies for implementing those recommendations; (2) identifies likely obstacles to their implementation; and (3) charts a course for successfully navigating and overcoming those challenges. Methods: Iterative and consensual processes were employed throughout the Summit and the development of this manuscript. Results: The conclusion of the Summit culminated in several consensus points, including: (1) Eating disorder outcomes and prevention efforts can be improved by implementing creative health education initiatives that focus on societal perceptions, early detection, and timely, effective intervention; (2) Such initiatives should be geared toward parents/guardians, families, other caretakers, and frontline healthcare providers in order to maximize impact; (3) Those afflicted with eating disorders, their loved ones, and the eating disorders community as a whole would benefit from greater accessibility to affordable, quality care, as well as greater transparency and accountability on the part of in-hospital, residential, and outpatient health care providers with respect to their qualifications, methodologies, and standardized outcomes; (4) Those with lived experience with eating disorders, their loved ones, health care providers, and the eating disorders community as a whole, also would benefit from the establishment and maintenance of treatment program accreditation, professional credentialing, and treatment type and levels of care guidelines; and (5) The establishment and implementation of effective, empirically/evidence-based standards of care requires research across a diverse range of populations, adequate private and government funding, and the free exchange of ideas and information among all who share a commitment to understanding, treating, and, ultimately, markedly diminishing the negative impact of eating disorders. Conclusions: Widespread uptake and implementation of these recommendations has the potential to unify and advance the eating disorders field and ultimately improve the lives of those affected. A cross-disciplinary group of eating disorder professionals, thought leaders, and persons with lived experience have come together and reached a consensus on issues that are fundamental to the battle against the life-threatening and life-altering illnesses that are eating spectrum disorders. Those issues include: (1) the need for early detection, intervention, prevention, and evidenced-based standards of care; (2) the critical need to make specialized care more accessible and affordable to all those in need; (3) the importance of developing uniform, evidenced-based standards of care; (4) the need for funding and conducting eating spectrum disorder research; and (5) the indispensability of advocacy, education, and legislation where these illnesses are concerned. During the consensus process, the authors also arrived at strategies for implementing their recommendations, identified likely obstacles to their implementation, and charted a course for successfully navigating and overcoming those challenges. Above all else, the authors demonstrated that consensus in the field of eating spectrum disorders is possible and achievable and, in doing so, lit a torch of hope that is certain to light the path forward for years to come
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