89 research outputs found
Process chain approach to high-order perturbation calculus for quantum lattice models
A method based on Rayleigh-Schroedinger perturbation theory is developed that
allows to obtain high-order series expansions for ground-state properties of
quantum lattice models. The approach is capable of treating both lattice
geometries of large spatial dimensionalities d and on-site degrees of freedom
with large state space dimensionalities. It has recently been used to
accurately compute the zero-temperature phase diagram of the Bose-Hubbard model
on a hypercubic lattice, up to arbitrary large filling and for d=2, 3 and
greater [Teichmann et al., Phys. Rev. B 79, 100503(R) (2009)].Comment: 11 pages, 6 figure
Frustrated quantum antiferromagnetism with ultracold bosons in a triangular lattice
We propose to realize the anisotropic triangular-lattice Bose-Hubbard model
with positive tunneling matrix elements by using ultracold atoms in an optical
lattice dressed by a fast lattice oscillation. This model exhibits frustrated
antiferromagnetism at experimentally feasible temperatures; it interpolates
between a classical rotor model for weak interaction, and a quantum spin-1/2
-model in the limit of hard-core bosons. This allows to explore
experimentally gapped spin liquid phases predicted recently [Schmied et al.,
New J. Phys. {\bf 10}, 045017 (2008)].Comment: 6 pages, as published in EP
Exploring dynamic localization with a Bose-Einstein condensate
We report on the experimental observation of dynamic localization of a
Bose-Einstein condensate in a shaken optical lattice, both for sinusoidal and
square-wave forcing. The formulation of this effect in terms of a quasienergy
band collapse, backed by the excellent agreement of the observed collapse
points with the theoretical predictions, suggests the feasibility of systematic
quasienergy band engineering.Comment: 7 pages, 4 figure
Engineering spin waves in a high-spin ultracold Fermi gas
We report on the detailed study of multi-component spin-waves in an s=3/2
Fermi gas where the high spin leads to novel tensorial degrees of freedom
compared to s = 1/2 systems. The excitations of a spin-nematic state are
investigated from the linear to the nonlinear regime, where the tensorial
character is particularly pronounced. By tuning the initial state we engineer
the tensorial spin-wave character, such that the magnitude and sign of the
counterflow spin-currents are effectively controlled. A comparison of our data
with numerical and analytical results shows excellent agreement.Comment: 9 pages, 4 figure
Systematic, early rhythm control strategy for atrial fibrillation in patients with or without symptoms:the EAST-AFNET 4 trial
AIMS: Clinical practice guidelines restrict rhythm control therapy to patients with symptomatic atrial fibrillation (AF). The EAST-AFNET 4 trial demonstrated that early, systematic rhythm control improves clinical outcomes compared to symptom-directed rhythm control. METHODS AND RESULTS: This prespecified EAST-AFNET 4 analysis compared the effect of early rhythm control therapy in asymptomatic patients (EHRA score I) to symptomatic patients. Primary outcome was a composite of death from cardiovascular causes, stroke, or hospitalization with worsening of heart failure or acute coronary syndrome, analyzed in a time-to-event analysis. At baseline, 801/2633 (30.4%) patients were asymptomatic [mean age 71.3 years, 37.5% women, mean CHA(2)DS(2)-VASc score 3.4, 169/801 (21.1%) heart failure]. Asymptomatic patients randomized to early rhythm control (395/801) received similar rhythm control therapies compared to symptomatic patients [e.g. AF ablation at 24 months: 75/395 (19.0%) in asymptomatic; 176/910 (19.3%) symptomatic patients, P = 0.672]. Anticoagulation and treatment of concomitant cardiovascular conditions was not different between symptomatic and asymptomatic patients. The primary outcome occurred in 79/395 asymptomatic patients randomized to early rhythm control and in 97/406 patients randomized to usual care (hazard ratio 0.76, 95% confidence interval [0.6; 1.03]), almost identical to symptomatic patients. At 24 months follow-up, change in symptom status was not different between randomized groups (P = 0.19). CONCLUSION: The clinical benefit of early, systematic rhythm control was not different between asymptomatic and symptomatic patients in EAST-AFNET 4. These results call for a shared decision discussing the benefits of rhythm control therapy in all patients with recently diagnosed AF and concomitant cardiovascular conditions (EAST-AFNET 4; ISRCTN04708680; NCT01288352; EudraCT2010-021258-20)
Longer and better lives for patients with atrial fibrillation:the 9th AFNET/EHRA consensus conference
Aims: Recent trial data demonstrate beneficial effects of active rhythm management in patients with atrial fibrillation (AF) and support the concept that a low arrhythmia burden is associated with a low risk of AF-related complications. The aim of this document is to summarize the key outcomes of the 9th AFNET/EHRA Consensus Conference of the Atrial Fibrillation NETwork (AFNET) and the European Heart Rhythm Association (EHRA). Methods and results: Eighty-three international experts met in MĂŒnster for 2 days in September 2023. Key findings are as follows: (i) Active rhythm management should be part of the default initial treatment for all suitable patients with AF. (ii) Patients with device-detected AF have a low burden of AF and a low risk of stroke. Anticoagulation prevents some strokes and also increases major but non-lethal bleeding. (iii) More research is needed to improve stroke risk prediction in patients with AF, especially in those with a low AF burden. Biomolecules, genetics, and imaging can support this. (iv) The presence of AF should trigger systematic workup and comprehensive treatment of concomitant cardiovascular conditions. (v) Machine learning algorithms have been used to improve detection or likely development of AF. Cooperation between clinicians and data scientists is needed to leverage the potential of data science applications for patients with AF. Conclusions: Patients with AF and a low arrhythmia burden have a lower risk of stroke and other cardiovascular events than those with a high arrhythmia burden. Combining active rhythm control, anticoagulation, rate control, and therapy of concomitant cardiovascular conditions can improve the lives of patients with AF
Genome-wide association meta-analyses and fine-mapping elucidate pathways influencing albuminuria
Abstract: Increased levels of the urinary albumin-to-creatinine ratio (UACR) are associated with higher risk of kidney disease progression and cardiovascular events, but underlying mechanisms are incompletely understood. Here, we conduct trans-ethnic (n = 564,257) and European-ancestry specific meta-analyses of genome-wide association studies of UACR, including ancestry- and diabetes-specific analyses, and identify 68 UACR-associated loci. Genetic correlation analyses and risk score associations in an independent electronic medical records database (n = 192,868) reveal connections with proteinuria, hyperlipidemia, gout, and hypertension. Fine-mapping and trans-Omics analyses with gene expression in 47 tissues and plasma protein levels implicate genes potentially operating through differential expression in kidney (including TGFB1, MUC1, PRKCI, and OAF), and allow coupling of UACR associations to altered plasma OAF concentrations. Knockdown of OAF and PRKCI orthologs in Drosophila nephrocytes reduces albumin endocytosis. Silencing fly PRKCI further impairs slit diaphragm formation. These results generate a priority list of genes and pathways for translational research to reduce albuminuria
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