421 research outputs found

    Flat-band ferromagnetism induced by off-site repulsions

    Full text link
    Density matrix renormalization group method is used to analyze how the nearest-neighbor repulsion V added to the Hubbard model on 1D triangular lattice and a railway trestle (t-t') model will affect the electron-correlation dominated ferromagnetism arising from the interference (frustration). Obtained phase diagram shows that there is a region in smaller-t' side where the critical on-site repulsion above which the system becomes ferromagnetic is reduced when the off-site repulsion is introduced.Comment: 4 pages, RevTex, 6 figures in Postscript, to be published in Phys. Rev.

    Tight-binding study of high-pressure phase transitions in titanium: alpha to omega and beyond

    Full text link
    We use a tight-binding total energy method, with parameters determined from a fit to first-principles calculations, to examine the newly discovered gamma phase of titanium. Our parameters were adjusted to accurately describe the alpha Ti-omega Ti phase transition, which is misplaced by density functional calculations. We find a transition from omega Ti to gamma Ti at 102 GPa, in good agreement with the experimental value of 116 GPa. Our results suggest that current density functional calculations will not reproduce the omega Ti-gamma Ti phase transition, but will instead predict a transition from omega Ti to the bcc beta Ti phase.Comment: 3 encapsulated Postscript figures, submitted to Phyical Review Letter

    Characterization of Polymeric Proteins from Vitreous and Floury Sorghum Endosperm

    Get PDF
    Differences in protein content and composition between vitreous and floury endosperm were investigated using a number of different techniques. Differences in protein cross-linking between vitreous and floury endosperm were investigated using differential solubility, size exclusion chromatography (SEC), and analysis of sulfhydryl content and composition. Vitreous endosperm was found to have higher levels of total protein and kafirins, but floury endosperm had a higher proportion of γ-kafirins than the vitreous. Floury endosperm was found to have higher levels of SDS-soluble proteins than SDS-insoluble proteins extracted using sonication than vitreous endosperm. Conversely, vitreous endosperm had a greater proportion of the insoluble proteins. SEC analysis of the polymeric proteins revealed that the insoluble proteins had more polymeric proteins than did the soluble proteins, indicating greater cross-linking and a larger Mw distribution. Vitreous endosperm was also found to have a greater percentage (i.e., a higher ratio of disulfide to total sulfhydryls) of disulfide bonds than floury endosperm. These results show that the proteins in vitreous endosperm have a higher degree of cross-linking and a greater Mw distribution than those found in floury endosperm

    Photon and dilepton emission rates from high density quark matter

    Full text link
    We compute the rates of real and virtual photon (dilepton) emission from dense QCD matter in the color-flavor locked (CFL) phase, focusing on results at moderate densities (3-5 times the nuclear saturation density) and temperatures T80T\simeq80 MeV. We pursue two approaches to evaluate the electromagnetic (e.m.) response of the CFL ground state: (i) a direct evaluation of the photon self energy using quark particle/-hole degrees of freedom, and (ii) a Hidden Local Symmetry (HLS) framework based on generalized mesonic excitations where the ρ\rho meson is introduced as a gauge boson of a local SU(3) color-flavor group. The ρ\rho coupling to generalized two-pion states induces a finite width and allows to address the issue of vector meson dominance (VMD) in the CFL phase. We compare the calculated emissivities (dilepton rates) to those arising from standard hadronic approaches including in-medium effects. For rather large superconducting gaps (several tens of MeV at moderate densities), as suggested by both perturbative and nonperturbative estimates, the dilepton rates from CFL quark matter turn out to be very similar to those obtained in hadronic many-body calculations, especially for invariant masses above M0.3M\simeq0.3 GeV. A similar observation holds for (real) photon production.Comment: 18 pages, 12 figure

    Impact of percutaneous coronary intervention timing on 5-year outcome in patients with non-ST-segment elevation acute coronary syndromes. The ‘wait a day’ approach might be safer

    Get PDF
    Background The OPTIMA trial was a randomised multicentre trial exploring the influence of the timing of percutaneous coronary intervention (PCI) on patient outcomes in an intermediate to high risk non-ST-elevation acute coronary syndrome (NSTE-ACS) population. In order to decide the best treatment strategy for patients presenting with NSTEACS, long-term outcomes are essential. Methods Five-year follow-up data from 133 of the 142 patients could be retrieved (94 %). The primary endpoint was a composite of death and spontaneous myocardial infarction (MI). Spontaneous MI was defined as MI occurring more than 30 days after randomisation. Secondary endpoints were the individual outcomes of death, spontaneous MI or re-PCI. Results No significant difference with respect to the primary endpoint was observed (17.8 vs. 10.1 %; HR 1.55, 95 % CI: 0.73–4.22, p = 0.21). There was no significant difference in mortality rate. However, spontaneous MI was significantly more common in the group receiving immediate PCI (11.0 vs. 1.4 %; HR 4.46, 95 % CI: 1.21–16.50, p = 0.02). We did not find a significant difference between the groups with respect to re-PCI rate. Conclusion There was no difference in the composite of death and spontaneous MI. The trial suggests an increased long-term risk of spontaneous MI for patients treated with immediate PCI

    A genotype-guided strategy for oral P2Y₁₂ Inhibitors in primary PCI

    Get PDF
    BACKGROUND: It is unknown whether patients undergoing primary percutaneous coronary intervention (PCI) benefit from genotype-guided selection of oral P2Y12 inhibitors. METHODS: We conducted a randomized, open-label, assessor-blinded trial in which patients undergoing primary PCI with stent implantation were assigned in a 1:1 ratio to receive either a P2Y12 inhibitor on the basis of early CYP2C19 genetic testing (genotype-guided group) or standard treatment with either ticagrelor or prasugrel (standard-treatment group) for 12 months. In the genotype-guided group, carriers of CYP2C19*2 or CYP2C19*3 loss-of-function alleles received ticagrelor or prasugrel, and noncarriers received clopidogrel. The two primary outcomes were net adverse clinical events - defined as death from any cause, myocardial infarction, definite stent thrombosis, stroke, or major bleeding defined according to Platelet Inhibition and Patient Outcomes (PLATO) criteria - at 12 months (primary combined outcome; tested for noninferiority, with a noninferiority margin of 2 percentage points for the absolute difference) and PLATO major or minor bleeding at 12 months (primary bleeding outcome). RESULTS: For the primary analysis, 2488 patients were included: 1242 in the genotype-guided group and 1246 in the standard-treatment group. The primary combined outcome occurred in 63 patients (5.1%) in the genotype-guided group and in 73 patients (5.9%) in the standard-treatment group (absolute difference, -0.7 percentage points; 95% confidence interval [CI], -2.0 to 0.7; P<0.001 for noninferiority). The primary bleeding outcome occurred in 122 patients (9.8%) in the genotype-guided group and in 156 patients (12.5%) in the standard-treatment group (hazard ratio, 0.78; 95% CI, 0.61 to 0.98; P = 0.04). CONCLUSIONS: In patients undergoing primary PCI, a CYP2C19 genotype-guided strategy for selection of oral P2Y12 inhibitor therapy was noninferior to standard treatment with ticagrelor or prasugrel at 12 months with respect to thrombotic events and resulted in a lower incidence of bleeding. (Funded by the Netherlands Organization for Health Research and Development; POPular Genetics ClinicalTrials.gov number, NCT01761786; Netherlands Trial Register number, NL2872.)

    Cost Effectiveness of a CYP2C19 Genotype-Guided Strategy in Patients with Acute Myocardial Infarction:Results from the POPular Genetics Trial

    Get PDF
    INTRODUCTION: The POPular Genetics trial demonstrated that a CYP2C19 genotype-guided P2Y12 inhibitor strategy reduced bleeding rates compared with standard treatment with ticagrelor or prasugrel without increasing thrombotic event rates after primary percutaneous coronary intervention (PCI). OBJECTIVE: In this analysis, we aimed to evaluate the cost effectiveness of a genotype-guided strategy compared with standard treatment with ticagrelor or prasugrel. METHODS: A 1-year decision tree based on the POPular Genetics trial in combination with a lifelong Markov model was developed to compare costs and quality-adjusted life-years (QALYs) between a genotype-guided and a standard P2Y12 inhibitor strategy in patients with myocardial infarction undergoing primary PCI. The cost-effectiveness analysis was conducted from a Dutch healthcare system perspective. Within-trial survival and utility data were combined with lifetime projections to evaluate lifetime cost effectiveness for a cohort of 1000 patients. Costs and utilities were discounted at 4 and 1.5%, respectively, according to Dutch guidelines for health economic studies. Besides deterministic and probabilistic sensitivity analyses, several scenario analyses were also conducted (different time horizons, different discount rates, equal prices for P2Y12 inhibitors, and equal distribution of thrombotic events between the two strategies). RESULTS: Base-case analysis with a hypothetical cohort of 1000 subjects demonstrated 8.98 QALYs gained and €725,550.69 in cost savings for the genotype-guided strategy (dominant). The deterministic and probabilistic sensitivity analysis confirmed the robustness of the model and the cost-effectiveness results. In scenario analyses, the genotype-guided strategy remained dominant. CONCLUSION: In patients undergoing primary PCI, a CYP2C19 genotype-guided strategy compared with standard treatment with ticagrelor or prasugrel resulted in QALYs gained and cost savings. TRIAL REGISTRATION: Clinicaltrials.gov number: NCT01761786, Netherlands trial register number: NL2872

    Varespladib and cardiovascular events in patients with an acute coronary syndrome: the VISTA-16 randomized clinical trial

    Get PDF
    IMPORTANCE: Secretory phospholipase A2(sPLA2) generates bioactive phospholipid products implicated in atherosclerosis. The sPLA2inhibitor varespladib has favorable effects on lipid and inflammatory markers; however, its effect on cardiovascular outcomes is unknown. OBJECTIVE: To determine the effects of sPLA2inhibition with varespladib on cardiovascular outcomes. DESIGN, SETTING, AND PARTICIPANTS: A double-blind, randomized, multicenter trial at 362 academic and community hospitals in Europe, Australia, New Zealand, India, and North America of 5145 patients randomized within 96 hours of presentation of an acute coronary syndrome (ACS) to either varespladib (n = 2572) or placebo (n = 2573) with enrollment between June 1, 2010, and March 7, 2012 (study termination on March 9, 2012). INTERVENTIONS: Participants were randomized to receive varespladib (500 mg) or placebo daily for 16 weeks, in addition to atorvastatin and other established therapies. MAIN OUTCOMES AND MEASURES: The primary efficacy measurewas a composite of cardiovascular mortality, nonfatal myocardial infarction (MI), nonfatal stroke, or unstable angina with evidence of ischemia requiring hospitalization at 16 weeks. Six-month survival status was also evaluated. RESULTS: At a prespecified interim analysis, including 212 primary end point events, the independent data and safety monitoring board recommended termination of the trial for futility and possible harm. The primary end point occurred in 136 patients (6.1%) treated with varespladib compared with 109 patients (5.1%) treated with placebo (hazard ratio [HR], 1.25; 95%CI, 0.97-1.61; log-rank P = .08). Varespladib was associated with a greater risk of MI (78 [3.4%] vs 47 [2.2%]; HR, 1.66; 95%CI, 1.16-2.39; log-rank P = .005). The composite secondary end point of cardiovascular mortality, MI, and stroke was observed in 107 patients (4.6%) in the varespladib group and 79 patients (3.8%) in the placebo group (HR, 1.36; 95% CI, 1.02-1.82; P = .04). CONCLUSIONS AND RELEVANCE: In patients with recent ACS, varespladib did not reduce the risk of recurrent cardiovascular events and significantly increased the risk of MI. The sPLA2inhibition with varespladib may be harmful and is not a useful strategy to reduce adverse cardiovascular outcomes after ACS. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT01130246. Copyright 2014 American Medical Association. All rights reserved
    corecore