782 research outputs found

    Gamma-ray bursts and terrestrial planetary atmospheres

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    We describe results of modeling the effects on Earth-like planets of long-duration gamma-ray bursts (GRBs) within a few kiloparsecs. A primary effect is generation of nitrogen oxide compounds which deplete ozone. Ozone depletion leads to an increase in solar UVB radiation at the surface, enhancing DNA damage, particularly in marine microorganisms such as phytoplankton. In addition, we expect increased atmospheric opacity due to buildup of nitrogen dioxide produced by the burst and enhanced precipitation of nitric acid. We review here previous work on this subject and discuss recent developments, including further discussion of our estimates of the rates of impacting GRBs and the possible role of short-duration bursts.Comment: 12 pages including 5 figures (4 in color). Added discussion of GRB rates and biological effects. Accepted for publication in New Journal of Physics, for special issue "Focus on Gamma-Ray Bursts

    Multifunctional lanthanum tetraphosphonates: Flexible, ultramicroporous and proton-conducting hybrid frameworks

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    A new flexible ultramicroporous solid, La(H5DTMP)·7H2O (1), has been crystallized at room temperature using the tetraphosphonic acid H8DTMP, hexamethylenediamine-N,N,N′,N′-tetrakis(methylenephosphonic acid). Its crystal structure, solved by synchrotron powder X-ray diffraction, is characterised by a 3D pillared open-framework containing 1D channels filled with water. Upon dehydration, a new related crystalline phase, La(H5DTMP) (2) is formed. Partial rehydration of 2 led to La(H5DTMP)·2H2O (3). These new phases contain highly corrugated layers showing different degrees of conformational flexibility of the long organic chain. The combination of the structural study and the gas adsorption characterization (N2 and CO2) suggests an ultramicroporous flexible framework. NO isotherms are indicative of a strong irreversible adsorption of NO within the pores. Impedance data indicates that 1 is a proton-conductor with a conductivity of 8 × 10−3 S cm−1 at 297 K and 98% of relative humidity, and an activation energy of 0.25 eV.Proyecto nacional MAT2010-15175 (MICINN, España

    TRPV4 related skeletal dysplasias: a phenotypic spectrum highlighted byclinical, radiographic, and molecular studies in 21 new families

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    Extent: 8p.Background: The TRPV4 gene encodes a calcium-permeable ion-channel that is widely expressed, responds to many different stimuli and participates in an extraordinarily wide range of physiologic processes. Autosomal dominant brachyolmia, spondylometaphyseal dysplasia Kozlowski type (SMDK) and metatropic dysplasia (MD) are currently considered three distinct skeletal dysplasias with some shared clinical features, including short stature, platyspondyly, and progressive scoliosis. Recently, TRPV4 mutations have been found in patients diagnosed with these skeletal phenotypes. Methods and Results: We critically analysed the clinical and radiographic data on 26 subjects from 21 families, all of whom had a clinical diagnosis of one of the conditions described above: 15 with MD; 9 with SMDK; and 2 with brachyolmia. We sequenced TRPV4 and identified 9 different mutations in 22 patients, 4 previously described, and 5 novel. There were 4 mutation-negative cases: one with MD and one with SMDK, both displaying atypical clinical and radiographic features for these diagnoses; and two with brachyolmia, who had isolated spine changes and no metaphyseal involvement. Conclusions: Our data suggest the TRPV4 skeletal dysplasias represent a continuum of severity with areas of phenotypic overlap, even within the same family. We propose that AD brachyolmia lies at the mildest end of this spectrum and, since all cases described with this diagnosis and TRPV4 mutations display metaphyseal changes, we suggest that it is not a distinct entity but represents the mildest phenotypic expression of SMDK.Elena Andreucci, Salim Aftimos, Melanie Alcausin, Eric Haan, Warwick Hunter, Peter Kannu, Bronwyn Kerr, George McGillivray, RJ McKinlay Gardner, Maria G Patricelli, David Sillence, Elizabeth Thompson, Margaret Zacharin, Andreas Zankl, Shireen R Lamandé and Ravi Savariraya

    Women, men and coronary heart disease: a review of the qualitative literature

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    Aim. This paper presents a review of the qualitative literature which examines the experiences of patients with coronary heart disease. The paper also assesses whether the experiences of both female and male patients are reflected in the literature and summarizes key themes. Background. Understanding patients' experiences of their illness is important for coronary heart disease prevention and education. Qualitative methods are particularly suited to eliciting patients' detailed understandings and perceptions of illness. As much previous research has been 'gender neutral', this review pays particular attention to gender. Methods. Published papers from 60 qualitative studies were identified for the review through searches in MEDLINE, EMBASE, CINAHL, PREMEDLINE, PsychINFO, Social Sciences Citation Index and Web of Science using keywords related to coronary heart disease. Findings. Early qualitative studies of patients with coronary heart disease were conducted almost exclusively with men, and tended to generalize from 'male' experience to 'human' experience. By the late 1990s this pattern had changed, with the majority of studies including women and many being conducted with solely female samples. However, many studies that include both male and female coronary heart disease patients still do not have a specific gender focus. Key themes in the literature include interpreting symptoms and seeking help, belief about coronary 'candidates' and relationships with health professionals. The influence of social roles is important: many female patients have difficulties reconciling family responsibilities and medical advice, while male patients worry about being absent from work. Conclusions. There is a need for studies that compare the experiences of men and women. There is also an urgent need for work that takes masculinity and gender roles into account when exploring the experiences of men with coronary heart disease

    ‘You can’t stand on a corner and talk about it …’: Medicinal cannabis use, impression management and the analytical status of interviews

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    In this article, I examine how four medicinal cannabis users used impression management during in-depth, qualitative interviews to attend to self-presentational concerns. I examine the rhetorical strategies and narratives articulated by the participants while also attending to the role that I played in co-construction as the interviewer. Later I discuss how, although the participants’ accounts are occasioned by the interviews, they can still provide significant insights into the social worlds of the participants beyond the interviews. While discussions about whether to treat interviews as topic, resource or both are not new, I argue that we can treat interviews as both topic and resource because impression management is a product of the individual’s habitus and it and the accounts it produces are part of their social world

    Moving from the margins: The role of narrative and metaphor in health literacy

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    Narrative and metaphor are now recognised to be central to thought, language and communication, and consequently have relevance to discourse and action in many areas including health and wellbeing. In this paper, narrative and metaphor are examined in relation to areas relevant to health literacy. The ways in which narrative and metaphor relate to dimensions of health literacy identified by Zarcadoolas et al. (Zarcadoolas C, Pleasant A, Greer D. Advancing health literacy – a framework for understanding and action. San Francisco: John Wiley & Sons Inc; 2006.); fundamental, scientific, cultural, and civic are analysed. The work aims to provide a rationale for greater incorporation of narrative and metaphor in discussions and activities related to health literacy
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