306 research outputs found

    Effect of age on the prognostic value of left ventricular function in patients with acute coronary syndrome:a prospective registry study

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    Objective: This study aims to study the prognostic impact of LV function on mortality and examine the effect of age on the prognostic value of left ventricular function. Ā Methods: We examined the Myocardial Ischaemia National Audit Project (MINAP) registry (2006-2010) data with a mean follow up of 2.1 years. LV function was categorized into good (ejection fraction (EF) ā‰„50%), moderate (EF 30-49%) and poor (EF <30%) categories. Cox-proportional hazards models were constructed to examine the prognostic significance of LV function in different age groups (<65, 65-74, 75-84 and ā‰„85 years) on all-cause mortality adjusting for baseline variables. Ā Results: Of 424,848 patients, LV function data available for 123,609. Multiple imputations were used to impute missing values of LV function and the final sample for analyses were drawn from 414,305. After controlling for confounders, 339,887 participants were included in the regression models. For any age group, mortality was higher with worsening degree of LV impairment. Increased age reduced the adverse prognosis associated with reduced LV function (hazard ratios (HRs) of death comparing poor LV function to good LV function were 2.11 95%CI 1.88-2.37 for age <65 years and 1.28 95%CI 1.20-1.36 for age ā‰„85 years. Older patients had a high mortality risk even in those with good LV function. HRs of mortality for ā‰„85 compared to <65 years (HR=1.00) within good, moderate and poor ejection fractions groups were 5.89, 4.86 and 3.43, respectively. Ā Conclusions: In patients with ACS, clinicians should interpret the prognostic value of LV function taking into account patientā€™s age

    Spatial heterogeneities in structural temperature cause Kovacsā€™ expansion gap paradox in aging of glasses

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    Volume and enthalpy relaxation of glasses after a sudden temperature change has been extensively studied since Kovacsā€™ seminal work. One observes an asymmetric approach to equilibrium upon cooling versus heating and, more counterintuitively, the expansion gap paradox, i.e., a dependence on the initial temperature of the effective relaxation time even close to equilibrium when heating. Here, we show that a distinguishable-particle lattice model can capture both the asymmetry and the paradox. We quantitatively characterize the energetic states of the particle configurations using a physical realization of the fictive temperature called the structural temperature, which, in the heating case, displays a strong spatial heterogeneity. The system relaxes by nucleation and expansion of warmer mobile domains having attained the final temperature, against cooler immobile domains maintained at the initial temperature. A small population of these cooler regions persists close to equilibrium, thus explaining the paradox

    Kovacs Effect Studied Using The Distinguishable Particles Lattice Model Of Glass

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    Kovacs effect is a characteristic feature of glassy relaxation. It consists in a non-monotonic evolution of the volume (or enthalpy) of a glass after a succession of two abrupt temperatures changes. The second change is performed when the instantaneous value of the volume coincides with the equilibrium one at the final temperature. While this protocol might be expected to yield equilibrium dynamics right after the second temperature change, the volume instead rises and reaches a maximum, the so-called Kovacs hump, before dropping again to the final equilibrium value. Kovacs effect constitutes one of the hallmarks of aging in glasses. In this paper we reproduce all features of the Kovacs hump by means of the Distinguishable Particles Lattice Model (DPLM) which is a particle model of structural glasses.Comment: 4 pages, 2 figure

    Arbitrage, Covered Interest Parity and Cointegration Analysis on the NTD/USD Forex Market Revisited

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    This study applies interest parity theory including Covered Interest Parity (CIP) to examine the 30-, 60-.90-, and 180-day maturities for the NTD/USD foreign exchange (FX) market. In the empirical unit root tests, we find that NTD/USD forward premium and interest rate spread present I(0) property. Empirical results are provided that interest rate differential appears stationary component; imply the stable relationship between Taiwan and USA on monetary policy. Using Taylor (1989)'s covered interest arbitrage model, the empirical results exhibit the absence of excess profit opportunities on New Taiwan Dollar (NTD) or US Dollar (USD) returns. Additionally, theoretical innovation approach of the cost-of-carry model is considered to evaluate the arbitrage opportunities in FX study. Accordingly, the covered interest parity condition generally continue to hold that almost zero-arbitrage results support FX market efficiency although the Federal Reserve implemented several rounds of quantitative easing after the peak of the 2008 financial crisis. Ultimately, Taiwanese FX market emerges to have been little affected by the increased crisis risks during the turbulent times because of the its limited development and market integration. Keywords: Covered Interest Parity, Market Integration, Granger Causality Tests, Cost-of-Carry model JEL Classifications: G1, G12, F3

    Towards Relating Fragile-To-Strong Transition to Fragile Glass

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    Glass formers are in general classified as strong or fragile depending on whether their relaxation rates follow Arrhenius or super-Arrhenius temperature dependence. There are however notable exceptions such as water, which exhibit a fragile-to-strong (FTS) transition and behave as fragile and strong respectively at high and low temperatures. In this work, the FTS transition is studied using a distinguishable-particle lattice model previously demonstrated to be capable of simulating both strong and fragile glasses [Phys. Rev. Lett. 125, 265703 (2020)]. Starting with a bimodal pair-interaction distribution appropriate for fragile glasses, we show that by narrowing down the energy dispersion in the low-energy component of the distribution, a FTS transition is observed. The transition occurs at a temperature at which the stretching exponent of the relaxation is minimized, in agreement with previous molecular dynamics simulations

    Large heat-capacity jump in cooling-heating of fragile glass from kinetic Monte Carlo simulations based on a two-state picture

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    The specific-heat capacity c v of glass formers undergoes a hysteresis when subjected to a cooling-heating cycle, with a larger c v and a more pronounced hysteresis for fragile glasses than for strong ones. Here we show that these experimental features, including the unusually large magnitude of c v of fragile glasses, are well reproduced by kinetic Monte Carlo and equilibrium study of a distinguishable particle lattice model incorporating a two-state picture of particle interactions. The large c v in fragile glasses is caused by a dramatic transfer of probabilistic weight from high-energy particle interactions to low-energy ones as temperature decreases
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