723 research outputs found
Looking at the Haldane Conjecture from a Grouptheoretical Point of View
Based on the Lieb-Schultz-Mattis construction we present a five parameter
family of Spin-1 Hamiltonians with degenerate groundstate. Starting from the
critical symmetric Hamiltonian, we look for those perturbations of the
symmetry, which leave the groundstate degenerate. We also discuss the
spin-3/2 -case.Comment: 9 pages RevTex 3.
Decay Modes of the Nuclear Continuum Excited in Proton-Nucleus Interactions
Supported by the National Science Foundation and Indiana Universit
A Pragmatic Approach to the Continuum Spectrum in Quasifree Scattering
This work was supported by the National Science Foundation Grant NSF PHY 81-14339 and by Indiana Universit
Decay Modes of the Nuclear Continuum Excited in Proton-Nucleus Interactions
This work was supported by the National Science Foundation Grant NSF PHY 78-22774 A02 & A03 and by Indiana Universit
Cigarette Smoking, Cessation, and Risk of Heart Failure With Preserved and Reduced Ejection Fraction
Background: Smoking is well-recognized as a risk factor for heart failure (HF). However, few studies have evaluated the prospective association of cigarette smoking and smoking cessation with heart failure with preserved ejection fraction (HFpEF) and heart failure with reduced ejection fraction (HFrEF) as distinct phenotypes. Objectives: The aim of this study was to quantify the association of cigarette smoking and smoking cessation with the incidence of HFpEF and HFrEF. Methods: In 9,345 ARIC (Atherosclerosis Risk In Communities) study White and Black participants without history of HF at baseline in 2005 (age range 61-81 years), we quantified the associations of several established cigarette smoking parameters (smoking status, pack-years, intensity, duration, and years since cessation) with physician-adjudicated incident acute decompensated HF using multivariable Cox models. Results: Over a median follow-up of 13.0 years, there were 1,215 incident HF cases. Compared with never smokers, current cigarette smoking was similarly associated with HFpEF and HFrEF, with adjusted HRs ∼2. There was a dose-response relationship for pack-years of smoking and HF. A more extended period of smoking cessation was associated with a lower risk of HF, but significantly elevated risk persisted up to a few decades for HFpEF and HFrEF. Conclusions: All cigarette smoking parameters consistently showed significant and similar associations with HFpEF and HFrEF. Smoking cessation significantly reduced the risk of HF, but excess HF risk persisted for a few decades. Our results strengthened the evidence that smoking is an important modifiable risk factor for HF and highlighted the importance of smoking prevention and cessation for the prevention of HF, including HFpEF
Recurrent Acute Decompensated Heart Failure Admissions for Patients With Reduced Versus Preserved Ejection Fraction (from the Atherosclerosis Risk in Communities Study)
Hospitals are required to report all-cause 30-day readmissions for patients discharged with heart failure. Same-cause readmissions have received less attention but may differ for heart failure with reduced ejection fraction (HFrEF) versus heart failure with preserved ejection fraction (HFpEF). The ARIC study began abstracting medical records for cohort members hospitalized with acute decompensated heart failure (ADHF) in 2005. ADHF was validated by physician review, with HFrEF defined by ejection fraction <50%. Recurrent admissions for ADHF were analyzed within 30 days, 90 days, 6 months, and 1 year of the index hospitalization using repeat-measures Cox regression models. All recurrent ADHF admissions per patient were counted rather than the more typical analysis of only the first occurring readmission. From 2005 to 2014, 1,133 cohort members survived at least 1 hospitalization for ADHF and had ejection fraction recorded. Half were classified as HFpEF. Patients with HFpEF were more often women and had more co-morbidities. The overall ADHF readmission rate was greatest within 30 days of discharge but was higher for patients with HFrEF (115 vs 88 readmissions per 100 person-years). After adjustments for demographics, year of admission, and co-morbidities, there was a trend for higher ADHF readmissions with HFrEF, relative to HFpEF, at 30 days (hazard ratio [HR] 1.41, 95% confidence interval [CI] 0.92 to 2.18), 90 days (HR 1.39, 95% CI 1.05 to 1.85), 6 months (HR 1.47, 95% CI, 1.18 to 1.84), and 1 year (HR 1.42, 95% CI 1.18 to 1.70) of follow-up. In conclusion, patients with HFrEF have a greater burden of short- and long-term readmissions for recurrent ADHF
Quasi-local Energy for Spherically Symmetric Spacetimes
We present two complementary approaches for determining the reference for the
covariant Hamiltonian boundary term quasi-local energy and test them on
spherically symmetric spacetimes. On the one hand, we isometrically match the
2-surface and extremize the energy. This can be done in two ways, which we call
programs I (without constraint) and II (with additional constraints). On the
other hand, we match the orthonormal 4-frames of the dynamic and the reference
spacetimes. Then, if we further specify the observer by requiring the reference
displacement to be the timelike Killing vector of the reference, the result is
the same as program I, and the energy can be positive, zero, or even negative.
If, instead, we require that the Lie derivatives of the two-area along the
displacement vector in both the dynamic and reference spacetimes to be the
same, the result is the same as program II, and it satisfies the usual
criteria: the energies are non-negative and vanish only for Minkowski (or
anti-de Sitter) spacetime.Comment: 16 pages, no figure
Screened Coulomb interactions in metallic alloys: II Screening beyond the single-site and atomic sphere approximations
A quantitative description of the configurational part of the total energy of
metallic alloys with substantial atomic size difference cannot be achieved in
the atomic sphere approximation: It needs to be corrected at least for the
multipole moment interactions in the Madelung part of the one-electron
potential and energy. In the case of a random alloy such interactions can be
accounted for only by lifting the atomic sphere and single-site approximations,
in order to include the polarization due to local environment effects.
Nevertheless a simple parameterization of the screened Coulomb interactions for
the ordinary single-site methods, including the generalized perturbation
method, is still possible. We obtained such a parameterization for bulk and
surface NiPt alloys, which allows one to obtain quantitatively accurate
effective interactions in this system.Comment: 24 pages, 2 figure
Prospective study of plasma high molecular weight kininogen and prekallikrein and incidence of coronary heart disease, ischemic stroke and heart failure
Introduction: High molecular weight kininogen (HK) and prekallikrein (PK) are proteins in the kallikrein/kinin system of the coagulation cascade. They play an important role in the contact activation system of the intrinsic coagulation pathway, renin-angiotensin activation, and inflammation. Hence these proteins have been posited to affect the occurrence of cardiovascular events and thus to be potential therapeutic targets. Previous case-control studies have provided inconsistent evidence for an association of HK and PK with cardiovascular disease. Methods: In the prospective population-based Atherosclerosis Risk in Communities(ARIC) Study, we used Cox proportional hazards regression models to investigate the association in 4195 middle-aged adults of plasma HK and PK concentrations in 1993–95 (linearly and in quartiles) with incident coronary heart disease, ischemic stroke, and heart failure through 2016. Results: Over a mean of 18 years follow-up, we identified incident cardiovascular events (coronary heart disease and ischemic stroke) in 618 participants and heart failure in 667. We observed no significant relation between HK or PK and cardiovascular disease or heart failure, before and after adjusting for several potential confounding variables. Conclusions: We found no compelling evidence to support an association of plasma HK or PK concentrations with incident CHD, ischemic stroke, or heart failure
Same-sign dileptons as a signature for heavy Majorana neutrinos in hadron-hadron collisions
We discuss the possibility of same-sign dileptons as a signature for Majorana
neutrinos. The production mechanism is given by a single heavy neutrino
production and decay proton-proton -> l^{\pm} N X -> l^{\pm} l^{\pm} X'. Cross
section and distributions are presented for the LHC energies.Comment: 07 pages, LaTeX; to be published in Physics Letters
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