2,849 research outputs found
Disentangling Sources of Quantum Entanglement in Quench Dynamics
Quantum entanglement may have various origins ranging from solely
interaction-driven quantum correlations to single-particle effects. Here, we
explore the dependence of entanglement on time-dependent single-particle basis
transformations in fermionic quantum many-body systems, thus aiming at
isolating single-particle sources of entanglement growth in quench dynamics.
Using exact diagonalization methods, for paradigmatic non-integrable models we
compare to the standard real space cut various physically motivated
bipartitions. Moreover, we search for a minimal entanglement basis using local
optimization algorithms, which at short to intermediate post-quench times
yields a significant reduction of entanglement beyond a dynamical Hartree-Fock
solution. In the long-time limit, we identify an asymptotic universality of
entanglement for weakly interacting systems, as well as a cross-over from
dominant real-space to momentum-space entanglement in Hubbard-models undergoing
an interaction quench. Finally, we discuss the relevance of our findings for
the development of tensor network based algorithms for quantum dynamics.Comment: Updated version with minor modification
Atrial Fibrillation and Myocardial Infarction: A Systematic Review and Appraisal of Pathophysiologic Mechanisms
A growing body of evidence suggests that atrial fibrillation (AF) is associated with myocardial infarction (MI). However, incidence and management of MI in AF is still undefined.
METHODS AND RESULTS:
We searched MEDLINE via PubMed and Cochrane database between 1965 and 2015. All observational clinical studies and interventional trials reporting 1-year incidence of MI in AF were included. We also discussed pathophysiological mechanisms, predictors, and therapeutic approaches to reduce the risk of MI in AF. Twenty-one observational studies and 10 clinical trials were included. The annual rate of MI in observational studies including AF patients ranged from 0.4% to 2.5%. Higher rates of MI were reported in AF patients with stable coronary artery disease (11.5%/year), vascular disease (4.47%/year), heart failure (2.9%/year), and in those undergoing coronary artery interventions (6.3%/year). However, lower annual rates have been described in AF patients from Eastern countries (0.2-0.3%/year), and in those enrolled in clinical trials (from 0.4 to 1.3%/year).
CONCLUSIONS:
AF patients had a significant residual risk of MI despite anticoagulant treatment. Coexistence of atherosclerotic risk factors and platelet activation account for the increased risk of MI in AF. Identification of high-risk AF patients is a needed first step to develop cost-effective approaches for prevention. A new score, the 2MACE score, has been recently developed to stratify MI risk in AF, and may help not only in allocating resources to high-risk groups, but also in design of studies examining novel therapies for prevention of MI in AF
Statins and non-alcoholic fatty liver disease
Dear Editor,
In April 9 issue, van den Berg et al1 report interesting results on
the indication for lipidâlowering treatment in a large cohort with
suspected nonâalcoholic fatty liver disease (NAFLD) within the
populationâbased Lifelines Cohort Study. Fatty liver index (FLI) â„60
was used as a proxy of NAFLD and the NAFLD fibrosis score (NFS)
to identify the NAFLD patients with suspected advanced fibrosis.
Cardiovascular disease (CVD) risk was established by the 2016
European society of Cardiology/European Atherosclerosis Society
(ESC/EAS) Guidelines for the Management of Dyslipidemias.2
Subjects with FLI â„ 60 (suspected NAFLD) had an increased 10â
year predicted cardiovascular risk compared to those with FLI < 60
with an approximately 2 times higher need for statin therapy based
on CVD risk prediction and their LDL cholesterol level. Subjects with
a FLI â„ 60 were more likely to be classified with type 2 diabetes,
Metabolic Syndrome (MetS), history of CVD and impaired renal function.
Interestingly, estimated 10âyear very high cardiovascular risk was
approximately 4 times higher in subjects with a NFS > 0.676 compared
to those with the absence of advanced fibrosis. Finally, indication for
statin treatment was positively associated with a FLI â„ 60 after controlling
for age, sex, current smoking, impaired renal function, and the
presence of MetS and its individual components. The above results
have an even greater relevance if we consider that all the subjects who
were already on statin therapy were subtracted from the analysis.
These findings may have an important clinical relevance and emphasize
the need for effective treatment with statins in patients with
NAFLD. Indeed, accumulating evidence suggests that CVD, rather
than liver disease, dictates the outcomes in NAFLD.3 Besides, in
most subjects NAFLD constitutes the hepatic component of MetS
and numerous patients have atherogenic dyslipidemia.
This study further supports the results of a previous study by our
group where under prescription of statins in patients with NAFLD
was observed.4 In fact, mild liver enzyme elevation remains a concern
and despite its proven efficacy and safety,5 statin administration
is sometimes limited by the worry about related side effects.
Indeed, there is a tendency of general physicians to discourage statin
use in patients with baseline elevation of serum liver enzymes and/
or to discontinue medication when minor alterations were appreciated.
Of note, in our study, statin underâuse was high also in patients
at very high CV risk such as those with a previous CV event.
This study by van den Berg et al further stresses the issue of
under prescription of statins in people with NAFLD and indication
for treatment, based on CV risk class and lowâdensity lipoprotein
cholesterol target according to ESC/EAS guidelines
Atherothrombosis and Oxidative Stress: Mechanisms and Management in Elderly
Significance: The incidence of cardiovascular events (CVEs) increases with age, representing the main cause of
death in an elderly population. Aging is associated with overproduction of reactive oxygen species (ROS),
which may affect clotting and platelet activation, and impair endothelial function, thus predisposing elderly
patients to thrombotic complications.
Recent Advances: There is increasing evidence to suggest that aging is associated with an imbalance between
oxidative stress and antioxidant status. Thus, upregulation of ROS-producing enzymes such as nicotinamide
adenine dinucleotide phosphate (NADPH) oxidase and myeloperoxidase, along with downregulation of antioxidant
enzymes, such as superoxide dismutase and glutathione peroxidase, occurs during aging. This imbalance
may predispose to thrombosis by enhancing platelet and clotting activation and eliciting endothelial
dysfunction. Recently, gut-derived products, such as trimethylamine N-oxide (TMAO) and lipopolysaccharide,
are emerging as novel atherosclerotic risk factors, and gut microbiota composition has been shown to change by
aging, and may concur with the increased cardiovascular risk in the elderly.
Critical Issues: Antioxidant treatment is ineffective in patients at risk or with cardiovascular disease. Further,
anti-thrombotic treatment seems to work less in the elderly population.
Future Directions: Interventional trials with antioxidants targeting enzymes implicated in aging-related
atherothrombosis are warranted to explore whether modulation of redox status is effective in lowering CVEs in
the elderly
An Exegetical and Phenomenological Study of 1â3 John as a Model for Developing Biblical Community Through Spiritual Leadership Practices
Pastors and church leaders have been trusted with the New Testament responsibility of building biblical community characterized by koinonia. For contemporary pastors, this means developing this community while addressing internal conflicts and an increasing level of opposition from a post-Christian societal culture. The leadership approach of the Apostle John and the biblical principles in the epistles of 1â3 John serve as a model for building and maintaining biblical community while addressing internal and external challenges. Spiritual leadership theory (Fry, 2003) and organizational culture (Cameron & Quinn, 2011; Schein, 1986, 1990) provide valid theoretical constructs that are compatible with the Scriptural approach as taught and modeled by the Apostle John. This study included an exegetical analysis of the New Testament epistles of 1â3 John, as well as a phenomenological study of contemporary church leaders as a model for developing biblical community through spiritual leadership practices in a post- Christian culture. The exegetical analysis produced seven broad leadership themes. The biblical themes formed the basis for in-depth qualitative interview questions that 11 Assemblies of God presbyters responded to. The results integrated Scripture, leadership theory, and phenomenological findings to serve as a guide for contemporary church leaders who are endeavoring to build and maintain biblical community in a post-Christian society
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