246 research outputs found

    The Aharonov-Bohm effect for an exciton

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    We study theoretically the exciton absorption on a ring shreded by a magnetic flux. For the case when the attraction between electron and hole is short-ranged we get an exact solution of the problem. We demonstrate that, despite the electrical neutrality of the exciton, both the spectral position of the exciton peak in the absorption, and the corresponding oscillator strength oscillate with magnetic flux with a period Φ0\Phi_0---the universal flux quantum. The origin of the effect is the finite probability for electron and hole, created by a photon at the same point, to tunnel in the opposite directions and meet each other on the opposite side of the ring.Comment: 13 RevTeX 3.0 pages plus 4 EPS-figures, changes include updated references and an improved chapter on possible experimental realization

    Spin dependent scattering of a domain-wall of controlled size

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    Magnetoresistance measurements in the CPP geometry have been performed on single electrodeposited Co nanowires exchange biased on one side by a sputtered amorphous GdCo layer. This geometry allows the stabilization of a single domain wall in the Co wire, the thickness of which can be controlled by an external magnetic field. Comparing magnetization, resistivity, and magnetoresistance studies of single Co nanowires, of GdCo layers, and of the coupled system, gives evidence for an additional contribution to the magnetoresistance when the domain wall is compressed by a magnetic field. This contribution is interpreted as the spin dependent scattering within the domain wall when the wall thickness becomes smaller than the spin diffusion length.Comment: 9 pages, 13 figure

    Effects of glucagon-like peptide-1 receptor agonists liraglutide and semaglutide on cardiovascular and renal outcomes across body mass index categories in type 2 diabetes: Results of the LEADER and SUSTAIN 6 trials

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    35 and ≥35 kg/m2), and CV and kidney outcomes with GLP-1 RA versus placebo were analysed. All baseline BMI data from LEADER (n = 9331) and SUSTAIN 6 (n = 3290) were included (91% and 92% of patients with overweight or obesity, respectively). In SUSTAIN 6, nominally significant heterogeneity of semaglutide efficacy by baseline BMI was observed for CV death/myocardial infarction/stroke (major adverse CV events, primary outcome of both25, ≥25-&ltAssociations between body mass index (BMI) and the cardiovascular (CV) and kidney efficacy of glucagon-like peptide-1 receptor agonists (GLP-1 RAs) in patients with type 2 diabetes (T2D) are uncertain; therefore, data analysed separately from the Liraglutide Effect and Action in Diabetes: Evaluation of Cardiovascular Outcome Results (LEADER) trial and the Trial to Evaluate Cardiovascular and Other Long-term Outcomes with Semaglutide in Subjects with Type 2 Diabetes (SUSTAIN 6) were examined. These international, randomized, placebo-controlled trials investigated liraglutide and semaglutide (both subcutaneous) in patients with T2D and at high risk of CV events. In post hoc analyses, patients were categorized by baseline BMI (<25, ≥25-<30, ≥30-<35 and ≥35 kg/m2), and CV and kidney outcomes with GLP-1 RA versus placebo were analysed. All baseline BMI data from LEADER (n = 9331) and SUSTAIN 6 (n = 3290) were included (91% and 92% of patients with overweight or obesity, respectively). In SUSTAIN 6, nominally significant heterogeneity of semaglutide efficacy by baseline BMI was observed for CV death/myocardial infarction/stroke (major adverse CV events, primary outcome of both; Pinteraction =.02); otherwise, there was no statistical heterogeneity for either GLP-1 RA versus placebo across BMI categories for key CV and kidney outcomes. The lack of statistical heterogeneity from these cardiorenal outcomes implies that liraglutide and semaglutide may be beneficial for many patients and is probable not to depend on their baseline BMI, but further study is needed.therefore, data analysed separately from the Liraglutide Effect and Action in Diabetes: Evaluation of Cardiovascular Outcome Results (LEADER) trial and the Trial to Evaluate Cardiovascular and Other Long-term Outcomes with Semaglutide in Subjects with Type 2 Diabetes (SUSTAIN 6) were examined. These international, randomized, placebo-controlled trials investigated liraglutide and semaglutide (both subcutaneous) in patients with T2D and at high risk of CV events. In post hoc analyses, patients were categorized by baseline BMI (&ltAssociations between body mass index (BMI) and the cardiovascular (CV) and kidney efficacy of glucagon-like peptide-1 receptor agonists (GLP-1 RAs) in patients with type 2 diabetes (T2D) are uncertainPinteraction =.02)30, ≥30-&ltotherwise, there was no statistical heterogeneity for either GLP-1 RA versus placebo across BMI categories for key CV and kidney outcomes. The lack of statistical heterogeneity from these cardiorenal outcomes implies that liraglutide and semaglutide may be beneficial for many patients and is probable not to depend on their baseline BMI, but further study is needed

    Relativistic K shell decay rates and fluorescence yields for Zn, Cd and Hg

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    In this work we use the multiconfiguration Dirac-Fock method to calculate the transition probabilities for all possible decay channels, radiative and radiationless, of a K shell vacancy in Zn, Cd and Hg atoms. The obtained transition probabilities are then used to calculate the corresponding fluorescence yields which are compared to existing theoretical, semi-empirical and experimental results

    Avaliação bioeconômica de estratégias de suplementação de novilhos zebuínos mantidos em pastagens diferidas de capim-marandu no período seco

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    RESUMO O objetivo com este trabalho foi avaliar estratégias de suplementação sobre o consumo de suplemento, comportamento e desempenho de novilhos zebuínos mantidos em pastagem de capim-marandu (Urochloa brizantha cv. Marandu) diferido. Foi utilizado delineamento inteiramente casualizado para testar cinco estratégias de suplementação: sal mineral (SM), sal proteinado com 25% de ureia (SP) e três multimisturas (45,5% NDT) com 10% (MM10), 15% (MM 15), ou 20% (MM20) de ureia. Foram utilizados vinte novilhos com peso inicial 300±24,9kg, sendo quatro por tratamento, mantidos em cinco piquetes de 3,4ha rotacionados semanalmente, de julho a outubro de 2010. Os dados foram submetidos à ANOVA, usando o Teste de Tukey para comparar as médias (P<0,05); entretanto, a análise econômica determinou a melhor estratégia. A ingestão de suplementos foi alterada (P<0,05) pela estratégia de suplementação, sendo de: 106, 196, 852, 666 e 400 g/animal/dia para SM, SP, MM10, MM15 e MM20, respectivamente. O aumento do consumo de suplementos não alterou o tempo de pastejo ou ruminação/ócio (P>0,05). SM resultou em perda de peso (-137 g/animal/dia). Utilizando-se o SP praticamente manteve o peso dos novilhos. Entretanto, para obtenção de ganho de peso, as multimisturas devem ser utilizadas (P<0,05). Nesses casos, o ganho de peso diário chegou a 324 g/animal (MM10). Baseado nos resultados econômicos, a melhor estratégia foi MM20, seguida de MM10

    Dapagliflozin and cardiovascular outcomes in type 2 diabetes

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    BACKGROUND The cardiovascular safety profile of dapagliflozin, a selective inhibitor of sodium– glucose cotransporter 2 that promotes glucosuria in patients with type 2 diabetes, is undefined. METHODS We randomly assigned patients with type 2 diabetes who had or were at risk for atherosclerotic cardiovascular disease to receive either dapagliflozin or placebo. The primary safety outcome was a composite of major adverse cardiovascular events (MACE), defined as cardiovascular death, myocardial infarction, or ischemic stroke. The primary efficacy outcomes were MACE and a composite of cardiovascular death or hospitalization for heart failure. Secondary efficacy outcomes were a renal composite (≥40% decrease in estimated glomerular filtration rate to <60 ml per minute per 1.73 m2 of body-surface area, new end-stage renal disease, or death from renal or cardiovascular causes) and death from any cause. RESULTS We evaluated 17,160 patients, including 10,186 without atherosclerotic cardiovascular disease, who were followed for a median of 4.2 years. In the primary safety outcome analysis, dapagliflozin met the prespecified criterion for noninferiority to placebo with respect to MACE (upper boundary of the 95% confidence interval [CI], <1.3; P<0.001 for noninferiority). In the two primary efficacy analyses, dapagliflozin did not result in a lower rate of MACE (8.8% in the dapagliflozin group and 9.4% in the placebo group; hazard ratio, 0.93; 95% CI, 0.84 to 1.03; P=0.17) but did result in a lower rate of cardiovascular death or hospitalization for heart failure (4.9% vs. 5.8%; hazard ratio, 0.83; 95% CI, 0.73 to 0.95; P=0.005), which reflected a lower rate of hospitalization for heart failure (hazard ratio, 0.73; 95% CI, 0.61 to 0.88); there was no between-group difference in cardiovascular death (hazard ratio, 0.98; 95% CI, 0.82 to 1.17). A renal event occurred in 4.3% in the dapagliflozin group and in 5.6% in the placebo group (hazard ratio, 0.76; 95% CI, 0.67 to 0.87), and death from any cause occurred in 6.2% and 6.6%, respectively (hazard ratio, 0.93; 95% CI, 0.82 to 1.04). Diabetic ketoacidosis was more common with dapagliflozin than with placebo (0.3% vs. 0.1%, P=0.02), as was the rate of genital infections that led to discontinuation of the regimen or that were considered to be serious adverse events (0.9% vs. 0.1%, P<0.001). CONCLUSIONS In patients with type 2 diabetes who had or were at risk for atherosclerotic cardiovascular disease, treatment with dapagliflozin did not result in a higher or lower rate of MACE than placebo but did result in a lower rate of cardiovascular death or hospitalization for heart failure, a finding that reflects a lower rate of hospitalization for heart failure. (Funded by AstraZeneca; DECLARE–TIMI 58 ClinicalTrials.gov number, NCT01730534.
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