1,532 research outputs found

    Origin and demographic history of the endemic Taiwan spruce (Picea morrisonicola)

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    Taiwan spruce (Picea morrisonicola) is a vulnerable conifer species endemic to the island of Taiwan. A warming climate and competition from subtropical tree species has limited the range of Taiwan spruce to the higher altitudes of the island. Using seeds sampled from an area in the central mountain range of Taiwan, 15 nuclear loci were sequenced in order to measure genetic variation and to assess the long-term genetic stability of the species. Genetic diversity is low and comparable to other spruce species with limited ranges such as Picea breweriana, Picea chihuahuana, and Picea schrenkiana. Importantly, analysis using approximate Bayesian computation (ABC) provides evidence for a drastic decline in the effective population size approximately 0.3–0.5 million years ago (mya). We used simulations to show that this is unlikely to be a false-positive result due to the limited sample used here. To investigate the phylogenetic origin of Taiwan spruce, additional sequencing was performed in the Chinese spruce Picea wilsonii and combined with previously published data for three other mainland China species, Picea purpurea, Picea likiangensis, and P. schrenkiana. Analysis of population structure revealed that P. morrisonicola clusters most closely with P. wilsonii, and coalescent analyses using the program MIMAR dated the split to 4–8 mya, coincidental to the formation of Taiwan. Considering the population decrease that occurred after the split, however, led to a much more recent origin

    Sliver® modules - a crystalline silicon technology of the future

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    A new technique has been devised for the manufacture of thin (<60µm) highly efficient single crystalline solar cells. Novel methods of encapsulating these Sliver® solar cells have also been devised. Narrow grooves are formed through a 1-2mm thick wafer. Device processing (diffusion, oxidation, deposition) is performed on the wafer, so that each of the narrow strips becomes a solar cell. The strips are then detached from the wafer and laid on their sides, which greatly increases the surface area of solar cell that can be obtained from the wafer. Further gains of a factor of two can be obtained by utilising a simple method of static concentration. Large decreases in processing effort (up to 30-fold) and silicon usage (up to 10-fold) per m2 of module are possible. The size, thickness and bifacial nature of the cells create the opportunity for a wide variety of module architectures and applications

    The SLIC Study: Size and Lung Function in Children

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    This dataset contains Body composition data (Whole body impedance from Bio-electrical impedance analysis and total body water from deuterium analysis) collected as part of the Size and Lung function In Children (SLIC) Study and a subset from Montagnese et al, Eur J Clin Nutr 2013 and reported in the manuscript entitled “Ethnic variability in body size, proportions and composition in children aged 5 to 11 years: Is ethnic-specific calibration of bio-electrical impedance required?” published in PLOS One

    Early life influences on the development of chronic obstructive pulmonary disease.

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    There is increasing evidence that chronic obstructive pulmonary disease (COPD) is not simply a disease of old age that is largely restricted to heavy smokers, but may be associated with insults to the developing lung during foetal life and the first few years of postnatal life, when lung growth and development are rapid. A better understanding of the long-term effects of early life factors, such as intrauterine growth restriction, prenatal and postnatal exposure to tobacco smoke and other pollutants, preterm delivery and childhood respiratory illnesses, on the subsequent development of chronic respiratory disease is imperative if appropriate preventive and management strategies to reduce the burden of COPD are to be developed. The extent to which insults to the developing lung are associated with increased risk of COPD in later life depends on the underlying cause, timing and severity of such derangements. Suboptimal conditions in utero result in aberrations of lung development such that affected individuals are born with reduced lung function, which tends to remain diminished throughout life, thereby increasing the risk both of wheezing disorders during childhood and subsequent COPD in genetically susceptible individuals. If the current trend towards the ever-increasing incidence of COPD is to be reversed, it is essential to minimize risks to the developing lung by improvements in antenatal and neonatal care, and to reduce prenatal and postnatal exposures to environmental pollutants, including passive tobacco smoke. Furthermore, adult physicians need to recognize that lung disease is potentially associated with early life insults and provide better education regarding diet, exercise and avoidance of smoking to preserve precious reserves of lung function in susceptible adults. This review focuses on factors that adversely influence lung development in utero and during the first 5 years of life, thereby predisposing to subsequent COPD

    Cluster coherent potential approximation for electronic structure of disordered alloys

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    We extend the single-site coherent potential approximation (CPA) to include the effects of non-local disorder correlations (alloy short-range order) on the electronic structure of random alloy systems. This is achieved by mapping the original Anderson disorder problem to that of a selfconsistently embedded cluster. This cluster problem is then solved using the equations of motion technique. The CPA is recovered for cluster size Nc=1N_{c}=1, and the disorder averaged density-of-states (DOS) is always positive definite. Various new features, compared to those observed in CPA, and related to repeated scattering on pairs of sites, reflecting the effect of SRO are clearly visible in the DOS. It is explicitly shown that the cluster-CPA method always yields positive-definite DOS. Anderson localization effects have been investigated within this approach. In general, we find that Anderson localization sets in before band splitting occurs, and that increasing partial order drives a continuous transition from an Anderson insulator to an incoherent metal.Comment: 7 pages, 6 figures. submitted to PR

    Temperature dependent magnetic anisotropy in metallic magnets from an ab-initio electronic structure theory: L1_0-ordered FePt

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    On the basis of a first-principles, relativistic electronic structure theory of finite temperature metallic magnetism, we investigate the variation of magnetic anisotropy, K, with magnetisation, M, in metallic ferromagnets. We apply the theory to the high magnetic anisotropy material, L1_0-ordered FePt, and find its uniaxial K consistent with a magnetic easy axis perpendicular to the Fe/Pt layering for all M and to be proportional to M^2 for a broad range of values of M. For small M, near the Curie temperature, the calculations pick out the easy axis for the onset of magnetic order. Our results are in good agreement with recent experimental measurements on this important magnetic material.Comment: 4 pages, 2 figure

    Acceptability, Precision and Accuracy of 3D Photonic Scanning for Measurement of Body Shape in a Multi-Ethnic Sample of Children Aged 5-11 Years: The SLIC Study.

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    Information on body size and shape is used to interpret many aspects of physiology, including nutritional status, cardio-metabolic risk and lung function. Such data have traditionally been obtained through manual anthropometry, which becomes time-consuming when many measurements are required. 3D photonic scanning (3D-PS) of body surface topography represents an alternative digital technique, previously applied successfully in large studies of adults. The acceptability, precision and accuracy of 3D-PS in young children have not been assessed
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