2,879 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
Development and application of innovative strategies for identification and characterization of viruses
Come testimoniato dalla pandemia COVID-19, la capacitaÌ di identificare rapidamente e caratterizzare geneticamente i virus emergenti, con un focus su quelli con impatto zoonotico, eÌ sempre piuÌ importante per la salute pubblica. I virus hanno tassi di mutazione elevati e possono essere coinvolti in frequenti eventi di ricombinazione e riassortimento. Queste proprietaÌ evolutive portano ad un'alta diversitaÌ genetica e all'emergenza di nuove varianti che possono avere un impatto zoonotico, virulenza e diffusione piuÌ elevati. In uno scenario come questo, disporre di protocolli di laboratorio e di pipeline bioinformatiche capaci di identificare e caratterizzare tempestivamente varianti virali emergenti eÌ cruciale in piani di early warning volti a prevenire o controllare tempestivamente nuove minacce infettive. Questa tesi si concentra sull'identificazione e caratterizzazione dei dati di sequenziamento genetico, sviluppando un flusso di lavoro completo per l'analisi dei dati NGS, partendo dai dati grezzi generati con differenti approcci di sequenziamento, fino alla creazione della sequenza consenso e all'applicazione di metodi filogenetici e filodinamici per studiare le dinamiche evolutive. Per la caratterizzazione di SARS-CoV-2, agente causativo della pandemia COVID-19, sono stati sviluppati protocolli ad hoc ed eÌ stata condotta una comparazione tra le tecnologie di sequenziamento di seconda (MiSeq, Illumina) e terza (MinION, Nanopore) generazione. Le tecnologie di sequenziamento di seconda generazione e il loro protocollo sono stati applicati all'analisi genetica di SARS-CoV-2 identificato in un gatto domestico, rivelando un'infezione con la variante B.1.177. Il miglioramento, l'ottimizzazione e l'applicazione delle analisi bioinformatiche dei dati NGS sono stati realizzati anche per l'identificazione e caratterizzazione del genoma completo di Hantavirus rilevato nei topi. Inoltre, utilizzando un approccio di sequenziamento diretto, cosiÌ detto âuntargetedâ, eÌ stato possibile caratterizzare il genoma di due virus a DNA nei pappagalli in Italia: il Polyomavirus e un possibile nuovo Circovirus. Sono stati inoltre applicati approcci bioinformatici anche per lâanalisi e lo studio del genoma del virus influenzale aviario ad alta patogenicitaÌ (sottotipo H5) (HPAI). In particolare, attraverso la generazione del genoma completo di centinaia di virus H5 HPAI identificati durante le ondate epidemiche italiane del 2020-2023 che hanno colpito volatili domestici e selvatici e la successiva applicazione di analisi filogenetiche e filogeografiche bayesiane, eÌ stato possibile rilevare la co-circolazione di diversi genotipi virali, ricostruire le dinamiche di diffusione del patogeno sul territorio nazionale ed esplorare il ruolo svolto dai diversi ospiti coinvolti nellâinfezione. Ma lo studio del genoma dei virus HPAI non si eÌ limitato alla situazione nazionale e alle specie aviarie. Una grave epidemia causata ancora una volta da virus H5 HPAI ha colpito i gatti in Polonia nellâestate del 2023. Le analisi molecolari ed evolutive applicate al genoma completo dei virus coinvolti nellâinfezione hanno svelato la circolazione di un virus con mutazioni capaci di aumentare lâadattamento del virus aviario al mammifero e ha consentito di chiarire che tutti gli animali coinvolti nellâevento epidemico erano stati esposti ad una comune fonte di infezione, verosimilmente di origine alimentare. I risultati generati nel presente progetto di dottorato sottolineano la strategicitaÌ del dato genetico e delle analisi bioinformatiche per comprendere le dinamiche di emergenza, evoluzione e disseminazione dei virus e per fornire informazioni chiave nella valutazione del rischio associato ai patogeni virali.As testified by the COVID-19 pandemic, the ability to rapidly identify and genetically characterize emerging viruses, with focus on ones with zoonotic impact, is increasingly crucial for public health. Viruses have high mutation rates and may be involved in frequent recombination and reassortment events. These evolutionary properties lead to high genetic diversity and the emergence of new variants that may have higher zoonotic impact, virulence, and increased spread. In a scenario like this, having laboratory protocols and bioinformatic pipelines capable of promptly identifying and characterizing emerging viral variants is crucial in early warning plans aimed at preventing or promptly controlling new infectious threats. This thesis focuses on the identification and characterization of genetic sequencing data, developing a comprehensive workflow for NGS data analysis, starting from raw data generated using different sequencing approaches to the consensus sequence creation and the phylogenetic and phylodynamic methods application to study evolutionary dynamics. For the characterization of SARS-CoV-2, causative agent of the COVID-19 pandemic, specific protocols were developed, and a comparison was conducted between second-generation sequencing technologies (MiSeq, Illumina) and third-generation sequencing technologies (MinION, Nanopore). Second-generation sequencing technologies and their protocol were applied to the genetic analysis of SARS-CoV-2 identified in a domestic cat, revealing an infection with the B.1.177 variant. Improvements, optimizations, and the application of bioinformatic analyses of NGS data were also accomplished for the identification and characterization of the complete genome of Hantavirus detected in mice. Additionally, using an "untargeted" direct sequencing approach, the genome of two DNA viruses in parrots in Italy, namely Polyomavirus and a possible new Circovirus, could be characterized. Bioinformatic approaches were also applied to the analysis and study of the genome of highly pathogenic avian influenza virus (subtype H5) (HPAI). Specifically, by generating the complete genome of hundreds of H5 HPAI viruses identified during the Italian epidemic waves of 2020-2023 that affected domestic and wild birds and subsequently applying Bayesian phylogenetic and phylogeographic analyses, it was possible to reveal the co-circulation of different viral genotypes, reconstruct the pathogen's spread dynamics across the national territory, and explore the role played by different hosts in the infection. However, the study of the genome of HPAI viruses was not limited to the national situation and avian species. A severe epidemic, caused once again by H5 HPAI viruses, affected cats in Poland in the summer of 2023. Molecular and evolutionary analyses applied to the complete genome of the viruses involved in the infection revealed the circulation of a virus with mutations capable of increasing the adaptation of the avian virus to mammals and clarified that all animals involved in the epidemic event had been exposed to a common source of infection, presumably of food origin. The results generated in this PhD project emphasize the strategic importance of genetic data and bioinformatic analyses in understanding the dynamics of emergence, evolution, and dissemination of viruses and providing key information in the assessment of the risk associated with viral pathogens
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
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
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
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