1,537 research outputs found

    Spin Torque Dynamics with Noise in Magnetic Nano-System

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    We investigate the role of equilibrium and nonequilibrium noise in the magnetization dynamics on mono-domain ferromagnets. Starting from a microscopic model we present a detailed derivation of the spin shot noise correlator. We investigate the ramifications of the nonequilibrium noise on the spin torque dynamics, both in the steady state precessional regime and the spin switching regime. In the latter case we apply a generalized Fokker-Planck approach to spin switching, which models the switching by an Arrhenius law with an effective elevated temperature. We calculate the renormalization of the effective temperature due to spin shot noise and show that the nonequilibrium noise leads to the creation of cold and hot spot with respect to the noise intensity.Comment: 10 pages, 7 figure

    Applying Domain Knowledge from Structured Citation Formats to Text and Data Mining: Examples Using the CITE Architecture

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    Domain knowledge expressed in structured citation formats can be exploited in data mining. We propose four structural properties of canonically cited texts, then look at to two classic problems in the study of the scholia, or ancient scholarly commentary, found in the manuscripts of the Iliad. We cluster citations of scholia to analyze their distribution in different manuscripts; this leads to a revised view of how the manuscripts\u27 scribes drew on their source material. Correlated frequencies of named entities suggest that one group of manuscripts had access to material more closely based on the work of the greatest Hellenistic editor of Homer, Aristarchus of Samothrace

    Anisotropy of ultra-thin ferromagnetic films and the spin reorientation transition

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    The influence of uniaxial anisotropy and the dipole interaction on the direction of the magnetization of ultra-thin ferromagnetic films in the ground-state is studied. The ground-state energy can be expressed in terms of anisotropy constants which are calculated in detail as function of the system parameters and the film thickness. In particular non-collinear spin arrangements are taken into account. Conditions for the appearance of a spin reorientation transition are given and analytic results for the width of the canted phase and its shift in applied magnetic fields associated with this transition are derived.Comment: 6 pages, RevTeX

    A Plasma {\beta} Transition Within a Propagating Flux Rope

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    We present a 2.5D MHD simulation of a magnetic flux rope (FR) propagating in the heliosphere and investigate the cause of the observed sharp plasma beta transition. Specifically, we consider a strong internal magnetic field and an explosive fast start, such that the plasma beta is significantly lower in the FR than the sheath region that is formed ahead. This leads to an unusual FR morphology in the first stage of propagation, while the more traditional view (e.g. from space weather simulations like Enlil) of a `pancake' shaped FR is observed as it approaches 1 AU. We investigate how an equipartition line, defined by a magnetic Weber number, surrounding a core region of a propagating FR can demarcate a boundary layer where there is a sharp transition in the plasma beta. The substructure affects the distribution of toroidal flux, with the majority of the flux remaining in a small core region which maintains a quasi-cylindrical structure. Quantitatively, we investigate a locus of points where the kinetic energy density of the relative inflow field is equal to the energy density of the transverse magnetic field (i.e. effective tension force). The simulation provides compelling evidence that at all heliocentric distances the distribution of toroidal magnetic flux away from the FR axis is not linear; with 80% of the toroidal flux occurring within 40% of the distance from the FR axis. Thus our simulation displays evidence that the competing ideas of a pancaking structure observed remotely can coexist with a quasi-cylindrical magnetic structure seen in situ.Comment: 11 pages of text + 6 figures. Accepted to ApJ on 16 Oct 201

    Archaeology of the Planned Location of the Toyota Motor Manufacturing Plant, San Antonio, Bexar County, Texas

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    From October 2002 to January 2004, the Center for Archaeological Research (CAR) of The University of Texas at San Antonio conducted archaeological investigations for the City of San Antonio in a 2,570.25-acre project area that is the future site of the San Antonio Toyota Motor Manufacturing Plant. The work was conducted under Texas Antiquities Permit No. 2982 with Dr. Steve A. Tomka, CAR Director, serving as Principal Investigator. The project included the reconnaissance of over 500 acres of the project area, the excavation of 376 shovel tests, 250 mechanical auger borings, and 42 backhoe and Gradall trenches. The backhoe and Gradall trenches were dug for geoarchaeological investigations and in one instance to search for a presumed historic cemetery. Reassessment for National Register of Historic Places and State Archeological Landmark status was conducted for 16 previously documented archaeological sites (41BX125, 41BX349, 41BX652, 41BX653, 41BX654, 41BX655, 41BX656, 41BX657, 41BX658, 41BX659, 41BX660, 41BX661, 41BX662, 41BX676, 41BX681, and 41BX832) and five newly identified sites (41BX1571–41BX1575). Of the 21 sites examined during this project, 12 are prehistoric, seven are historic and two have both prehistoric and historic components. The prehistoric sites are lithic and burned rock scatters, possibly the remnants of campsites. Diagnostic artifacts found in previous surveys indicate Archaic and Late Prehistoric time frames. The historic sites present are farmstead-ranch complexes including residential structures and outbuildings. Also encountered were tenant farmer residences and a small brick kiln. The historic components are primarily late-nineteenth and early-twentieth-century, although original surveys noted early-nineteenth-century artifacts. All artifacts collected are curated at the Center for Archaeological Research laboratory facility

    Z2_2 topology and superconductivity from symmetry lowering of a 3D Dirac Metal Au2_2Pb

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    3D Dirac semi-metals (DSMs) are materials that have massless Dirac electrons and exhibit exotic physical properties It has been suggested that structurally distorting a DSM can create a Topological Insulator (TI), but this has not yet been experimentally verified. Furthermore, quasiparticle excitations known as Majorana Fermions have been theoretically proposed to exist in materials that exhibit superconductivity and topological surface states. Here we show that the cubic Laves phase Au2_2Pb has a bulk Dirac cone above 100 K that gaps out upon cooling at a structural phase transition to create a topologically non trivial phase that superconducts below 1.2 K. The nontrivial Z2_2 = -1 invariant in the low temperature phase indicates that Au2_2Pb in its superconducting state must have topological surface states. These characteristics make Au2_2Pb a unique platform for studying the transition between bulk Dirac electrons and topological surface states as well as studying the interaction of superconductivity with topological surface states

    Effect of fenugreek (Trigonella foenum-graecum) seed powder on lipid profile: A single blind placebo controlled study

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    Background: Dyslipidemia is one of the most prevalent risk factors contributing to atherosclerotic cardiovascular disease. Clinical trials have demonstrated that treatment of dyslipidemia reduces cardiovascular events. Fenugreek seed powder supplementation has lipid-lowering activity, but has not been studied extensively. In light of this, we undertook the present study at tertiary care hospital in Amravati, Maharashtra, with the aim of studying the effect of fenugreek seed powder on serum lipid profile in patients with dyslipidemia & to determine the adverse effects of it. Methods: The study was a single blind placebo controlled study conducted on 60 patients with dyslipidemia from June 2022 to November 2022, after meeting inclusion and exclusion criteria. Results: It was found significant decrease in serum total cholesterol (237.32 to 204.51mg/dl) p value 0.05, without any major side effects. Conclusion: Fenugreek seed powder significantly lowers serum total cholesterol, LDL cholesterol and triglyceride levels in dyslipidemia patients, with no effect on serum HDL cholesterol levels. fenugreek seed powder supplementation considerably improves lipid Profile. Hence it could be well-thought-out as an effective lipid lowering nutritional supplement. Further high quality & large scale studies are needed to decisively establish the clinical efficacy of fenugreek seed powder

    Sitagliptin in patients with non-alcoholic steatohepatitis: A randomized, placebo-controlled trial

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    AIM To evaluate the effect of sitagliptin vs placebo on histologic and non-histologic parameters of nonalcoholic steatohepatitis (NASH). METHODS Twelve patients with biopsy-proven NASH were randomized to sitagliptin (100 mg daily) (n = 6) or placebo (n = 6) for 24 wk. The primary outcome was improvement in liver fibrosis after 24 wk. Secondary outcomes included evaluation of changes in NAFLD activity score (NAS), individual components of NAS (hepatocyte ballooning, lobular inflammation, and steatosis), glycemic control and insulin resistance [including measurements of glycated hemoglobin (HbA1C) and adipocytokines], lipid profile including free fatty acids, adipose distribution measured using magnetic resonance imaging (MRI), and thrombosis markers (platelet aggregation and plasminogen activator inhibitor 1 levels). We also sought to determine the correlation between changes in hepatic fat fraction (%) [as measured using the Iterative Decomposition of water and fat with Echo Asymmetry and Least-squares estimation (IDEAL) MRI technique] and changes in hepatic steatosis on liver biopsy. RESULTS Sitagliptin was not significantly better than placebo at reducing liver fibrosis score as measured on liver biopsy (mean difference between sitagliptin and placebo arms, 0.40, P = 0.82). There were no significant improvements evident with the use of sitagliptin vs placebo for the secondary histologic outcomes of NAS total score as well as for the individual components of NAS. Compared to baseline, those patients who received sitagliptin demonstrated improved HbA1C (6.7% ± 0.4% vs 7.9% ± 1.0%, P = 0.02), and trended towards improved adiponectin levels (4.7 ± 3.5 μg/mL vs 3.9 ± 2.7 μg/mL, P = 0.06) and triglyceride levels (1.26 ± 0.43 mmol/L vs 2.80 ± 1.64 mmol/L, P = 0.08). However, when compared with placebo, sitagliptin did not cause a statistically significant improvement in HbA1C (mean difference, -0.7%, P = 0.19) nor triglyceride levels (mean difference -1.10 mmol/L, P = 0.19) but did trend towards improved adiponectin levels only (mean difference, 0.60 μg/mL, P = 0.095). No significant changes in anthropometrics, liver enzymes, other adipocytokines, lipid profile, thrombosis parameters, or adipose distribution were demonstrated. The MRI IDEAL procedure correlated well with steatosis scores obtained on liver biopsy in both groups at baseline and post-treatment, and the Spearman correlation coefficients ranged from r = 0.819 (baseline) to r = 0.878 (post-treatment), P = 0.002. CONCLUSION Sitagliptin does not improve fibrosis score or NAS after 24 wk of therapy. The MRI IDEAL technique may be useful for non-invasive measurement of hepatic steatosis

    Frequency and distribution of rare electrophoretic mobility variants in a population of human newborns in Ann Arbor, Michigan

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    We have summarized the frequency and distribution of the rare variants encountered during the screening of 258 815 allele products, the products of 51 different loci, in 3242 predominantly Caucasian (88 %) newborns. Seventy-nine different rare variants, representing 187 occurrences, were identified. Almost 60 % (46 of 79) of the rare variants occurred as singletons while another 20 % were seen in two unrelated individuals. No rare variants were detected at 18 loci while no variants, either rare or polymorphic, were detected at 14 loci. More rare variants were identified at loci that were classified as polymorphic and also at loci where the gene products exist as a monomer. A positive relationship was observed between variant frequency, either classes or copies, and subunit molecular mass.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65173/1/j.1469-1809.1987.tb01065.x.pd
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