14,037 research outputs found

    An equatorial ultra iron-poor star identified in BOSS

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    We report the discovery of SDSS J131326.89-001941.4, an ultra iron-poor red giant star ([Fe/H] ~ -4.3) with a very high carbon abundance ([C/Fe]~ +2.5). This object is the fifth star in this rare class, and the combination of a fairly low effective temperature (Teff ~ 5300 K), which enhances line absorption, with its brightness (g=16.9), makes it possible to measure the abundances of calcium, carbon and iron using a low-resolution spectrum from the Sloan Digital Sky Survey. We examine the carbon and iron abundance ratios in this star and other similar objects in the light of predicted yields from metal-free massive stars, and conclude that they are consistent. By way of comparison, stars with similarly low iron abundances but lower carbon-to-iron ratios deviate from the theoretical predictions.Comment: 6 pages, 4 figures, accepted for publication in A&

    Evaluating the effect of age and area of residence in the metal and metalloid contents in human hair and urban topsoils

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    The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.Monitoring the levels of trace elements in hair can allow estimating the effects of the geographical location and also can provide a notion of the metal body burden. However, the use of human hair is controversial due to the different confounding factors that could affect the presence of trace elements in hair. As a result, a comprehensive monitoring study was performed in Alcalá de Henares, one of the major cities in the Madrid region, Spain. Trace elements have been monitored in urban topsoils and in human hair of two well-defined and healthy groups of population: children (6–9 years) and adolescents (13–16 years). The city was divided into four areas or zones with different characteristics to assess the possible effect of area of residence and age in the presence of Al, As, Be, Cd, Cr, Cu, Hg, Mn, Pb, Sn, Ti, Tl and Zn in soils and hair. There is no current hypothesis that explains the possible effect of the area of monitoring in the distribution of Be, Cr, Ni, Sn and Ti found in these urban soils, maybe because urban soils receive high disturbance, and there are many factors involved. The presence of most of the trace elements monitored was significantly higher in the hair of the children population, except for Sn and Zn. This could be attributed mainly to dietary habits. Other factors influencing metal content in hair such as environmental factors would have had a minimal effect in the population groups here studied. Finally, none of the levels of trace elements studied in hair were significantly correlated with levels measured in the topsoils of public parks in Alcalá de Henares, with the exception of Pb in adolescent participants

    Effects of livestock pressure and vegetation cover on the spatial and temporal structure of soil microarthropod communities in Iberian rangelands

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    Forests, including their soils, play an important role since they represent a large reservoir of biodiversity. Current studies show that the diversity of soil fauna provides multiple ecosystem functions and services across biomes. However, anthropogenic practices often pose a threat to soil fauna because of changes in land use and soil mismanagement. In these terms, rangelands in the southwest of Spain present several problems of soil degradation related to livestock activity and soil erosion, the intensity of which compromises the soil fauna's functions in the ecosystem. Therefore, the aim of this study is to evaluate the response of community metrics and the spatial distribution of soil microarthropods to livestock activity and vegetation in such ecosystems. A photo interpretation analysis of an experimental catchment used as a study area was developed to identify and classify the intensity of livestock pressure. A total of 150 soil samples were collected throughout 2018. Soil biological (CO2 efflux) and physical-chemical parameters (pH, bulk density, organic matter, and water contents), and such meteorological variables as precipitation, temperature, and evapotranspiration were considered as variables affecting the composition of microarthropod communities in terms of taxa diversity, abundances, and their adaptation to soil environment (evaluated by QBS-ar index). Results showed higher abundance of microarthropods and higher adaptation to soil environment outside the influence of trees rather than beneath tree canopies. Moreover, the classification of livestock pressure revealed by the photo interpretation analysis showed low correlations with community structure, as well as with the occurrence of well-adapted microarthropod groups that were found less frequently in areas with evidence of intense livestock activity. Furthermore, abundances and adaptations followed different spatial patterns. Due to future climate changes and increasing anthropogenic pressure, it is necessary to continue the study of soil fauna communities to determine their degree of sensitivity to such changes

    Monitoring falls in gastric cancer mortality in Europe

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    We have considered trends in age-standardized mortality from gastric cancer in 25 individual European countries, as well as in the European Union (EU) as a whole, in six selected central-eastern European countries and in the Russian Federation over the period 1950-1999. Steady and persisting falls in rates were observed, and the fall between 1980 and 1999 was ∼50% in the EU, 45% in eastern Europe and 40% in Russia. However, the declines were greater in Russia and eastern Europe, since rates were much higher, in absolute terms. Joinpoint regression analysis indicated that the falls were proportionally greater in the last decade for men (-3.83% per year in the EU) and in the last 25 years for women (-3.67% per year in the EU) than in previous calendar years. Moreover, steady declines in gastric cancer mortality were observed in the middle-aged and the young population as well, suggesting that they are likely to persist in the near future. In terms of number of deaths avoided, however, the impact of the decline in gastric cancer mortality will be smaller, particularly in the E

    Chemical regeneration of thermally conditioned basalt fibres

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    The disposal of fibre reinforced composite materials is a problem widely debated in the literature. This work explores the ability to restore the mechanical properties of thermally conditioned basalt fibres through chemical treatments. Inorganic acid (HF) and alkaline (NaOH) treatments proved to be effective in regenerating the mechanical strength of recycled basalt fibres, with up to 94% recovery of the strength on treatment with NaOH. In particular, HF treatment proved to be less effective compared to NaOH, therefore pointing towards a more environmentally sustainable approach considering the disposal issues linked to the use of HF. Moreover, the strength regeneration was found to be dependent on the level of temperature experienced during the thermal treatment process, with decreasing effectiveness as a function of increasing temperature. SEM analysis of the fibres' lateral surfaces suggests that surface defects removal induced by the etching reaction is the mechanism controlling recovery of fibre mechanical properties. In addition, studies on the fracture toughness of the regenerated single fibres were carried out, using focussed ion beam (FIB) milling technique, to investigate whether any structural change in the bulk fibre occurred after thermal exposure and chemical regeneration. A significant increase in the fracture toughness for the regenerated fibres, in comparison with the as-received and heat-treated basalt ones, was measured

    Strength, jumping, and change of direction speed asymmetries are not associated with athletic performance in elite academy soccer players

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    The aims of the present study were twofold: 1) to measure inter-limb asymmetries from a battery of fitness tests in youth soccer players and, 2) determine the association between asymmetry and measures of athletic performance. Sixteen elite youth soccer players (14.7 ± 0.2 years) performed a single leg Abalakov test (ABK), change of direction (COD) test over 10 m (5 + 5) and 20 m (10 + 10), and an iso-inertial power test. Subjects also performed 10 m, 20 m and 30 m sprints and a bilateral countermovement jump (CMJ), which were correlated with all ABK, COD and iso-inertial asymmetry scores. A one-way repeated measures ANOVA showed significant differences between inter-limb asymmetry scores across multiple tests (p 0.05) between the different inter-limb asymmetry scores, and between asymmetry scores and athletic performance. These findings show the test-specific nature of asymmetries in youth soccer players, with the iso-inertial power test being the most sensitive in detecting asymmetry. Moreover, the results obtained suggest that inherent asymmetry in young soccer players did not negatively impact their performance

    Lung cancer mortality in European regions (1955-1997)

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    Background: The different spread of tobacco smoking across European countries has caused a substantial variability in lung cancer mortality. The objective of this investigation was to analyse the trends in lung cancer mortality rates in three broad European regions (Northern and Western countries, Eastern countries, and Mediterranean countries) during the second half of the 20th century. Patients and methods: Mortality data were obtained from the World Health Organisation database. Lung cancer mortality rates were age-standardised by the direct method to the world standard population. Trends from 1955 to 1997 were assessed by means of joinpoint regression analysis. Results: In men, rates in Eastern Europe increased to reach in the 1990s the highest values ever registered, while downward trends were observed in Northern and Western Europe since 1979, and in Mediterranean countries since the 1990s. In women, upward trends were observed in the three regions considered for the whole period. Conclusions: Different smoking prevalences over time explain the shift of almost one decade in the trends in Mediterranean men as compared with Northern and other Western European men. The persisting upward trends in women in the three regions are of concer
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