15 research outputs found

    The state of the Martian climate

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    60°N was +2.0°C, relative to the 1981–2010 average value (Fig. 5.1). This marks a new high for the record. The average annual surface air temperature (SAT) anomaly for 2016 for land stations north of starting in 1900, and is a significant increase over the previous highest value of +1.2°C, which was observed in 2007, 2011, and 2015. Average global annual temperatures also showed record values in 2015 and 2016. Currently, the Arctic is warming at more than twice the rate of lower latitudes

    Geographic population structure analysis of worldwide human populations infers their biogeographical origins

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    The search for a method that utilizes biological information to predict humans’ place of origin has occupied scientists for millennia. Over the past four decades, scientists have employed genetic data in an effort to achieve this goal but with limited success. While biogeographical algorithms using next-generation sequencing data have achieved an accuracy of 700 km in Europe, they were inaccurate elsewhere. Here we describe the Geographic Population Structure (GPS) algorithm and demonstrate its accuracy with three data sets using 40,000–130,000 SNPs. GPS placed 83% of worldwide individuals in their country of origin. Applied to over 200 Sardinians villagers, GPS placed a quarter of them in their villages and most of the rest within 50 km of their villages. GPS’s accuracy and power to infer the biogeography of worldwide individuals down to their country or, in some cases, village, of origin, underscores the promise of admixture-based methods for biogeography and has ramifications for genetic ancestry testing

    The Physics of the B Factories

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    Interdiffusion in Ni-rich, Ni-Cr-Al alloys at 1100 and 1200 °C: Part II. Diffusion coefficients and predicted concentration profiles

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    Ternary interdiffusion coefficients were measured in the Ni solid solution γ (fcc) phase of the Ni-Cr-Al system at 1100 and 1200 °C. Extensive use was made of both γ/γ and γ/γ + β (β-NiAl structure) diffusion couples. Two analysis techniques were employed to calculate the interdiffusion coefficients. When the Matano planes for Al and Cr were not coincident, numerous integral calculations were made to determine an average diffusion coefficient and to assess the effect of the noncoincidence of the Matano planes. The results of the diffusivity measurements showed that {Mathematical expression} is approximately four times greater than {Mathematical expression}, while {Mathematical expression} and {Mathematical expression} are of the same magnitude. For all concentrations, {Mathematical expression} is two to three times greater than {Mathematical expression}. Both {Mathematical expression} and {Mathematical expression} increase with increasing Al concentration, whereas {Mathematical expression} and {Mathematical expression} show little concentration dependence on Cr alone. A ternary, finite-difference interdiffusion model was employed to predict concentration profiles for the γ/γ couples utilizing the concentration dependence of the measured diffusivities. Good agreement was observed between the predicted and measured concentration profiles for both 1100 and 1200 °C
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