603 research outputs found

    Spin dynamics and magnetic interactions of Mn dopants in the topological insulator Bi2_2Te3_3

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    The magnetic and electronic properties of the magnetically doped topological insulator Bi2−x_{\rm 2-x}Mnx_{\rm x}Te3_3 were studied using electron spin resonance (ESR) and measurements of static magnetization and electrical transport. The investigated high quality single crystals of Bi2−x_{\rm 2-x}Mnx_{\rm x}Te3_3 show a ferromagnetic phase transition for x≥0.04x\geq 0.04 at TC≈12T_{C}\approx 12 K. The Hall measurements reveal a p-type finite charge-carrier density. Measurements of the temperature dependence of the ESR signal of Mn dopants for different orientations of the external magnetic field give evidence that the localized Mn moments interact with the mobile charge carriers leading to a Ruderman-Kittel-Kasuya-Yosida-type ferromagnetic coupling between the Mn spins of order 2-3 meV. Furthermore, ESR reveals a low-dimensional character of magnetic correlations that persist far above the ferromagnetic ordering temperature

    The femoral insertions of the anteromedial and posterolateral bundles of the anterior cruciate ligament: a radiographic evaluation

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    The aim of this radiographic study was to visualize the femoral insertion sites of the anteromedial (AM) and posterolateral (PL) bundle of the anterior cruciate ligament (ACL) on lateral radiographs in different angles of knee flexion to gain better understanding for arthroscopic femoral tunnel placement in ACL double bundle reconstruction. Four fresh cadaveric knees with an intact ACL were dissected to isolate the AM and PL bundle of the ACL. We obtained lateral radiographs of each knee over the range of 0°–90° flexion in 30° increments after painting the bundles with a radiopaque tantalum powder. The center of the radiographically marked femoral insertion was defined for each bundle on the lateral roentgenogram. We analyzed the relationship of knee flexion and the projection of the relative position of the femoral insertion sites of both bundles of the ACL on the lateral roentgenogram. The centre of the PL bundle visualized more anterior and distal than the centre of the AM bundle with the knee held in 90° flexion. The centers of the AM and PL bundle were horizontally aligned when the knee was flexed over 90°. The resulting images allow a radiographic description of the femoral insertion sites of both bundles in different angles of knee flexion. It is essential to be aware of the degree of knee flexion when drilling the femoral tunnels

    Carbon supported CdSe nanocrystals

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    Insights to the mechanism of CdSe nanoparticle attachment to carbon nanotubes following the hot injection method are discussed. It was observed that the presence of water improves the nanotube coverage while Cl containing media are responsible for the shape transformation of the nanoparticles and further attachment to the carbon lattice. The experiments also show that the mechanism taking place involves the right balance of several factors, namely, low passivated nanoparticle surface, particles with well-defined crystallographic facets, and interaction with an organics-free sp2 carbon lattice. Furthermore, this procedure can be extended to cover graphene by quantum dots.Comment: 5 pages, 5 figure

    Heritability of Body Mass Index: A comparison between the Netherlands and Spain.

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    A high body mass index (BMI) is commonly used as an index of overweight and obesity. There is persistent evidence of high heritability for variation in BMI, but the effects of common environment appear inconsistent across different European countries. Our objective was to compare genetic and environmental effects on BMI in a sample of twins from two different European countries with distinct population and cultural backgrounds. We analysed data of adult female twins from the Netherlands Twin Register (222 monozygotic [MZ] and 103 dizygotic [DZ] pairs) and the Murcia Twin Register (Spain; 202 MZ and 235 DZ pairs). BMI was based on self-reported weight and height. Dutch women were taller and heavier, but Spanish women had a significantly higher mean BMI. The age related weight increase was significantly stronger in the Spanish sample. Genetic analyses showed that genetic factors are the main contributors to variation in height, weight, and BMI, within both countries. For height and weight, estimates of genetic variances did not differ, but for height, the estimate for the environmental variance was significantly larger in Spanish women. For BMI, both the genetic and the environmental variance components were larger in Spanish than in Dutch women

    Distributional impacts of carbon pricing in developing Asia

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    Understanding who would be affected in which way by carbon pricing is pivotal for effective and socially equitable policy design, addressing climate change and reducing inequality. This paper focuses on eight key countries in developing Asia (Bangladesh, India, Indonesia, Pakistan, Philippines, Thailand, Turkey and Vietnam). By combining national household surveys with input-output data, we compare the distributional effects of four carbon pricing design options, including a globally harmonized carbon price, a national carbon price and sectoral carbon prices in the power and transport sectors, respectively. Our analysis reveals a substantial degree of variation regarding who would be affected across policy designs and countries. Looking into national carbon pricing as the most favourable policy option from an economic point of view, we find that differences in distributional outcomes are generally more pronounced within income groups than across income groups. These differences are mainly driven by households' energy use patterns, which vary across countries. Equally recycling revenues back to all citizens would overcompensate the burden of a carbon price for the poorest households in all countries. Carbon pricing can alter income distribution. With a focus on Bangladesh, India, Indonesia, Pakistan, Philippines, Thailand, Turkey and Vietnam, this study compares four types of carbon pricing schemes and finds substantial variation in distributional effects across policy designs and countries.Industrial Ecolog

    The geographic mosaic of herbicide resistance evolution in the common morning glory, Ipomoea purpurea: Evidence for resistance hotspots and low genetic differentiation across the landscape

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    Strong human‐mediated selection via herbicide application in agroecosystems has repeatedly led to the evolution of resistance in weedy plants. Although resistance can occur among separate populations of a species across the landscape, the spatial scale of resistance in many weeds is often left unexamined. We assessed the potential that resistance to the herbicide glyphosate in the agricultural weed Ipomoea purpurea has evolved independently multiple times across its North American range. We examined both adaptive and neutral genetic variations in 44 populations of I. purpurea by pairing a replicated dose–response greenhouse experiment with SSR genotyping of experimental individuals. We uncovered a mosaic pattern of resistance across the landscape, with some populations exhibiting high‐survival postherbicide and other populations showing high death. SSR genotyping revealed little evidence of isolation by distance and very little neutral genetic structure associated with geography. An approximate Bayesian computation (ABC) analysis uncovered evidence for migration and admixture among populations before the widespread use of glyphosate rather than the very recent contemporary gene flow. The pattern of adaptive and neutral genetic variations indicates that resistance in this mixed‐mating weed species appears to have evolved in independent hotspots rather than through transmission of resistance alleles across the landscape.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/113156/1/eva12290_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/113156/2/eva12290.pd

    Arthroscopic evaluation of the ACL double bundle structure

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    In order to describe the arthroscopic presence of the double bundle structure and to evaluate the value of different portals in knee arthroscopy, we assessed the AM and PL bundle anatomy. We prospectively examined the knees of 60 patients undergoing arthroscopic surgery for pathology unrelated to the ACL. Arthroscopy was performed in a two portal technique using an anterolateral (ALP) and an anteromedial (AMP) portal. With the arthroscope in the ALP, we could distinguish an AM and PL bundle in 28%. Switching the arthroscope to the AMP, differentiation of the bundles was possible in 67%. In all remaining cases visualization of the PL bundle was possible after retraction of the AM bundle. Use of AMP increased visualization of the PL bundle. It seems reasonable to perform arthroscopy for ACL reconstruction with the arthroscope in the AMP and to establish an additional medial working portal to increase the visualization of the femoral ACL insertion sites for optimal femoral tunnel placement

    Crystal Growth and Electronic Phase Diagram of 4\u3cem\u3ed\u3c/em\u3e-doped Na\u3csub\u3e1-\u3cem\u3eδ\u3c/em\u3e\u3c/sub\u3eFe\u3csub\u3e1-\u3cem\u3ex\u3c/em\u3e\u3c/sub\u3eRh\u3csub\u3e\u3cem\u3ex\u3c/em\u3e\u3c/sub\u3eAs in Comparison to 3\u3cem\u3ed\u3c/em\u3e-doped Na\u3csub\u3e1-\u3cem\u3eδ\u3c/em\u3e\u3c/sub\u3eFe\u3csub\u3e1-\u3cem\u3ex\u3c/em\u3e\u3c/sub\u3eCo\u3csub\u3e\u3cem\u3ex\u3c/em\u3e\u3c/sub\u3eAs

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    Single crystals of Na1−δFe1−xTxAs with T = Co, Rh have been grown using a self-flux technique. The crystals were thoroughly characterized by powder x-ray diffraction, magnetic susceptibility, and electronic transport with particular focus on the Rh-doped samples. Measurements of the specific heat and ARPES were conducted exemplarily for the optimally doped compositions. The spin-density wave transition (SDW) observed for samples with low Rh concentration (0≤x≤0.013) is fully suppressed in the optimally doped sample. The superconducting transition temperature (Tc) is enhanced from 10 K in Na1−δFeAs to 21 K in the optimally doped sample (x=0.019) of the Na1−δFe1−xRhxAs series and decreases for the overdoped compounds, revealing a typical shape for the superconducting part of the electronic phase diagram. Remarkably, the phase diagram is almost identical to that of Co-doped Na1−δFeAs, suggesting a generic phase diagram for both dopants
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