1,188 research outputs found

    Effects of melting, subduction-related metasomatism, and sub-solidus equilibration on the distribution of water contents in the mantle beneath the Rio Grande Rift

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    The distribution of water in the upper mantle plays a crucial role in the Earth's deep water cycle, magmatism, and plate tectonics. To better constrain how these large-scale geochemical systems operate, peridotite and pyroxenite mantle xenoliths from Kilbourne Hole (KH) and Rio Puerco (RP) along the Rio Grande Rift (NM, USA) were analyzed for water, and major and trace element contents. These xenoliths sample a lithosphere whose composition was influenced by subduction and rifting, and can be used to examine the effects of melting, metasomatism, and sub-solidus equilibration on the behavior of water. The first result is that in KH xenoliths, olivines underwent negligible H loss during xenolith ascent, i.e. preserved their mantle water contents. These olivine water contents are used to calculate mantle viscosities of 0.5–184 · 1021 Pa·s. These viscosity values are more than 40 times higher than those of the asthenosphere and show that KH peridotites represent samples from the lithosphere. The preservation of olivine water contents is exceptional for off-cratonic xenoliths, and the KH peridotites provide the first estimate of the average concentration of water in Phanerozoic continental mantle lithosphere at 81 ± 30 ppm H2O. The mantle lithosphere beneath the Rio Grande rift is nevertheless heterogeneous with water contents ranging from <0.5 to 120 ppm H2O in peridotites and from 227 to 400 ppm H2O in pyroxenites. A composite KH xenolith of a harzburgite cross-cut by a clinopyroxenite vein shows this heterogeneity at the cm scale. The second contribution of this study stems from the majority of the KH peridotites and two of the RP peridotites having major and trace elements that can be explained by partial melting without any need to invoke metasomatic processes. This allows to show that, prior to modelling the water content variation of each peridotite mineral during melting, a correction for sub-solidus equilibration has to be applied to the water contents of the minerals. Sub-solidus equilibration also provides an explanation for the discrepancy between the clinopyroxene/orthopyroxene ratio of water contents in natural peridotites worldwide and in laboratory experiments on water partitioning in peridotite minerals. Finally, the cryptically metasomatized peridotites, rare at KH and abundant at RP, as well as the pyroxenites, permit to decipher the origin and water contents of the metasomatic melts that affected the continental lithosphere beneath the Rio Grande Rift. Trace element modelling of the metasomatized KH and RP peridotites are consistent with metasomatism via melts that are of subduction origin. Melts in equilibrium with peridotites contain more water at RP (∼1 wt.% H2O) than at KH (∼0.5 wt.% H2O), although this did not result in a more water-rich mantle lithosphere at RP. Rio Puerco lies within the northern Rio Grande rift, proposed to have been affected by a flat slab subduction, which may explain the more hydrous and extensive metasomatism compared to the south, where KH is located

    Surviving rather than thriving: Understanding the experiences of women coaches using a theory of gendered social well-being

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    In shifting our gaze to the sociological impact of being in the minority, the purpose of this study was to substantiate a model of gendered social well-being to appraise women coaches’ circumstances, experiences and challenges as embedded within the social structures and relations of their profession. This is drawn on indepth interviews with a sample of head women coaches within the UK. The findings demonstrate that personal lives, relationships, social and family commitments were sidelined by many of the participants in order to meet the expectations of being a (woman) coach. We locate these experiences in the organisational practices of high performance sport which hinder women coaches from having meaningful control over their lives. The complexities of identity are also revealed through the interplay of gender with (dis)ability, age and whiteness as evidence of hegemonic femininity within the coaching profession. Consequently, for many women, coaching is experienced as a ‘developmental dead-end’

    Vitamin D and subsequent all-age and premature mortality: a systematic review

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    &lt;br&gt;Background: All-cause mortality in the population &#60; 65 years is 30% higher in Glasgow than in equally deprived Liverpool and Manchester. We investigated a hypothesis that low vitamin D in this population may be associated with premature mortality via a systematic review and meta-analysis.&lt;/br&gt; &lt;br&gt;Methods: Medline, EMBASE, Web of Science, the Cochrane Library and grey literature sources were searched until February 2012 for relevant studies. Summary statistics were combined in an age-stratified meta-analysis.&lt;/br&gt; &lt;br&gt;Results: Nine studies were included in the meta-analysis, representing 24,297 participants, 5,324 of whom died during follow-up. The pooled hazard ratio for low compared to high vitamin D demonstrated a significant inverse association (HR 1.19, 95% CI 1.12-1.27) between vitamin D levels and all-cause mortality after adjustment for available confounders. In an age-stratified meta-analysis, the hazard ratio for older participants was 1.25 (95% CI 1.14-1.36) and for younger participants 1.12 (95% CI 1.01-1.24).&lt;/br&gt; &lt;br&gt;Conclusions: Low vitamin D status is inversely associated with all-cause mortality but the risk is higher amongst older individuals and the relationship is prone to residual confounding. Further studies investigating the association between vitamin D deficiency and all-cause mortality in younger adults with adjustment for all important confounders (or using randomised trials of supplementation) are required to clarify this relationship.&lt;/br&gt

    Harnessing Interpretable and Unsupervised Machine Learning to Address Big Data from Modern X-ray Diffraction

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    The information content of crystalline materials becomes astronomical when collective electronic behavior and their fluctuations are taken into account. In the past decade, improvements in source brightness and detector technology at modern x-ray facilities have allowed a dramatically increased fraction of this information to be captured. Now, the primary challenge is to understand and discover scientific principles from big data sets when a comprehensive analysis is beyond human reach. We report the development of a novel unsupervised machine learning approach, XRD Temperature Clustering (X-TEC), that can automatically extract charge density wave (CDW) order parameters and detect intra-unit cell (IUC) ordering and its fluctuations from a series of high-volume X-ray diffraction (XRD) measurements taken at multiple temperatures. We apply X-TEC to XRD data on a quasi-skutterudite family of materials, (Cax_xSr1x_{1-x})3_3Rh4_4Sn13_{13}, where a quantum critical point arising from charge order is observed as a function of Ca concentration. We further apply X-TEC to XRD data on the pyrochlore metal, Cd2_2Re2_2O7_7, to investigate its two much debated structural phase transitions and uncover the Goldstone mode accompanying them. We demonstrate how unprecedented atomic scale knowledge can be gained when human researchers connect the X-TEC results to physical principles. Specifically, we extract from the X-TEC-revealed selection rule that the Cd and Re displacements are approximately equal in amplitude, but out of phase. This discovery reveals a previously unknown involvement of 5d25d^2 Re, supporting the idea of an electronic origin to the structural order. Our approach can radically transform XRD experiments by allowing in-operando data analysis and enabling researchers to refine experiments by discovering interesting regions of phase space on-the-fly

    Quality of life, characteristics and survival of patients with HIV and lymphoma

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    We sought to compare the quality of life (QOL), characteristics, and survival of patients with non-Hodgkin lymphoma (NHL) with and without human immunodeficiency virus (HIV) infection. Using the population-based cancer registry for Orange and San Diego Counties, We recruited 50 patients with HIV and systemic NHL (cases) and 50 age, sex and race-matched NHL patients without HIV (controls) diagnosed with NHL during 2002–2006. Patients completed a medical history survey and QOL instrument, the Functional Assessment of Human Immunodeficiency Virus Infection (FAHI) for cases and Functional Assessment of Cancer Therapy-General (FACT G) for controls. HIV-infected patients had worse overall QOL and survival than uninfected patients. QOL differences were more marked in the areas of functional, physical and social well-being than in the area of emotional well-being. HIV-infected patients had lower income and were less likely to have private insurance and more likely to have diffuse large B cell histology than uninfected patients. HIV-infected NHL patients had worse QOL and survival than uninfected patients, due to a combination of co-morbidity, aggressive histology and lack of social support. However, their emotional well-being was comparable to that of uninfected NHL patients and better than historical norms for the HIV-infected

    Pontocerebellar hypoplasia type 2: a neuropathological update

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    Pontocerebellar hypoplasia type 2 (PCH-2; MIM 277470), an autosomal recessive neurodegeneration with fetal onset, was studied in six autopsies with ages at death ranging between 1 and 22 years. Three patients were distantly related. A case of olivopontocerebellar hypoplasia (OPCH; MIM 225753) was studied for comparison. Typical findings are: short cerebellar folia with poor branching (“hypoplasia”), relative sparing of the vermis, sharply demarcated areas of full thickness loss of cerebellar cortex probably resulting from regression at an early stage of development, segmental loss of dentate nuclei with preserved islands and reactive changes, segmental loss in the inferior olivary nucleus with reactive changes, loss of ventral pontine nuclei with near absence of transverse pontine fibers and sparing of spinal anterior horn cells. Variable findings are: cystic cerebellar degeneration, found in two, with vascular changes limited to the cerebellum in one. Comparison to olivopontocerebellar hypoplasia (OPCH) strongly suggests a continuum of pathology between this disorder and PCH-2. Immunohistochemical evaluation of the endoplasmic reticulum stress response is negative. We conclude that the neuropathological findings in PCH-2 are sufficiently specific to enable an unequivocal diagnosis based on neuropathology

    Design and Synthesis of a Quintessential Self-Transmissible IncX1 Plasmid, pX1.0

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    DNA exchange in bacteria via conjugative plasmids is believed to be among the most important contributing factors to the rapid evolution- and diversification rates observed in bacterial species. The IncX1 plasmids are particularly interesting in relation to enteric bacteria, and typically carry genetic loads like antibiotic resistance genes and virulence factors. So far, however, a “pure” version of these molecular parasites, without genetic loads, has yet to be isolated from the environment. Here we report the construction of pX1.0, a fully synthesized IncX1 plasmid capable of horizontal transfer between different enteric bacteria. The designed pX1.0 sequence was derived from the consensus gene content of five IncX1 plasmids and three other, more divergent, members of the same phylogenetic group. The pX1.0 plasmid was shown to replicate stably in E. coli with a plasmid DNA per total DNA ratio corresponding to approximately 3–9 plasmids per chromosome depending on the growth phase of the host. Through conjugation, pX1.0 was able to self-transfer horizontally into an isogenic strain of E. coli as well as into two additional species belonging to the family Enterobacteriaceae. Our results demonstrate the immediate applicability of recent advances made within the field of synthetic biology for designing and constructing DNA systems, previously existing only in silica

    Adherence to physical activity recommendations and the influence of socio-demographic correlates – a population-based cross-sectional study

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    <p>Abstract</p> <p>Background</p> <p>Current physical activity guidelines acknowledge the importance of total health enhancing physical activity (HEPA) compared to leisure time physical activity or exercise alone. Assessing total HEPA may result in different levels of adherence to these as well as the strength and/or direction of associations observed between total HEPA and socio-demographic correlates. The aim of this study was to estimate the proportion of the population adhering to the recommendation of at least 30 minutes of HEPA on most days, and to examine the influences of socio-demographic correlates on reaching this recommendation.</p> <p>Methods</p> <p>Swedish adults aged 18–74 years (n = 1470) were categorized, based on population data obtained using the IPAQ, into low, moderately and highly physically active categories. Independent associations between the physical activity categories and socio-demographic correlates were studied using a multinomial logistic regression.</p> <p>Results</p> <p>Of the subjects, 63% (95% CI: 60.5–65.4) adhered to the HEPA recommendation. Most likely to reach the highly physical active category were those aged < 35 years (OR = 1.8; 95% CI: 1.1–3.3), living in small towns (OR = 1.8; 95% CI: 1.1–2.7) and villages (OR = 2.4; 95% CI: 1.6–3.7), having a BMI between 25.0–29.9 kg/m<sup>2 </sup>(OR = 2.7; 95% CI: 1.4–5.3) having a BMI < 25 kg/m<sup>2 </sup>(OR = 2.5; 95% CI: 1.3–4.9), or having very good (OR = 2.1; 95% CI: 1.3–3.3) or excellent self-perceived health (OR = 4.1; 95% CI: 2.4–6.8). Less likely to reach the high category were women (OR = 0.6; 95% CI: 0.5–0.9) and those with a university degree (OR = 0.5; 95% CI: 0.3–0.9). Similar, but less pronounced associations were observed for the moderate group. Gender-specific patterns were also observed.</p> <p>Conclusion</p> <p>Almost two-thirds of the Swedish adult population adhered to the physical activity recommendation. Due to a large diversity in levels of physical activity among population subgroups, social-ecological approaches to physical activity promotion may be warranted.</p
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