Complex paths for regular-to-chaotic tunneling rates

In generic Hamiltonian systems tori of regular motion are dynamically separated from regions of chaotic motion in phase space. Quantum mechanically these phase-space regions are coupled by dynamical tunneling. We introduce a semiclassical approach based on complex paths for the prediction of dynamical tunneling rates from regular tori to the chaotic region. This approach is demonstrated for the standard map giving excellent agreement with numerically determined tunneling rates.Comment: 5 pages, 4 figure

A new conceptual framework for revenge firesetting

Revenge has frequently been acknowledged to account for a relatively large proportion of motives in deliberate firesetting. However, very little is actually known about the aetiology of revenge firesetting. Theoretical approaches to revenge-seeking behaviour are discussed. A brief review of how revenge is accounted for in existing theoretical explanations of deliberate firesetting and the known characteristics of revenge firesetters are provided. On this basis, the authors suggest, as a motive, revenge firesetting has to date been misconceptualised. A new conceptual framework is thus proposed, paying particular attention to the contextual, affective, cognitive, volitional and behavioural factors which may influence and generate a single episode of revenge firesetting. Treatment implications and suggestions for future research are also provided

Eigenstate thermalization hypothesis through the lens of autocorrelation functions

Matrix elements of observables in eigenstates of generic Hamiltonians are described by the Srednicki ansatz within the eigenstate thermalization hypothesis (ETH). We study a quantum chaotic spin-fermion model in a one-dimensional lattice, which consists of a spin-1/2 XX chain coupled to a single itinerant fermion. In our study, we focus on translationally invariant observables including the charge and energy current, thereby also connecting the ETH with transport properties. Considering observables with a Hilbert-Schmidt norm of one, we first perform a comprehensive analysis of ETH in the model taking into account latest developments. A particular emphasis is on the analysis of the structure of the offdiagonal matrix elements $|\langle \alpha | \hat O | \beta \rangle|^2$ in the limit of small eigenstate energy differences $\omega = E_\beta - E_\alpha$. Removing the dominant exponential suppression of $|\langle \alpha | \hat O | \beta \rangle|^2$, we find that: (i) the current matrix elements exhibit a system-size dependence that is different from other observables under investigation, (ii) matrix elements of several other observables exhibit a Drude-like structure with a Lorentzian frequency dependence. We then show how this information can be extracted from the autocorrelation functions as well. Finally, our study is complemented by a numerical analysis of the fluctuation-dissipation relation for eigenstates in the bulk of the spectrum. We identify the regime of $\omega$ in which the well-known fluctuation-dissipation relation is valid with high accuracy for finite systems

Dissociation of a Hubbard--Holstein bipolaron driven away from equilibrium by a constant electric field

Using a variational numerical method we compute the time-evolution of the Holstein-Hubbard bipolaron from its ground state when at t=0 the constant electric field is switched on. The system is evolved taking into account full quantum effects until it reaches a quasi-stationary state. In the zero-field limit the current shows Bloch oscillations characteristic for the adiabatic regime where the electric field causes the bipolaron to evolve along the quasiparticle band. Bipolaron remains bound and the net current remains zero in this regime. At larger electric fields the system enters the dissipative regime with a finite steady-state current. Concomitantly, the bipolaron dissociates into two separate polarons. By examining different parameter regimes we show that the appearance of a finite steady-state current is inevitably followed by the dissociation of the bipolaron.Comment: 9 pages, 7 figure

Cost-effectiveness analysis of individual-level obesity treatment in paediatrics: A scoping review.

OBJECTIVES: This scoping review informs a health economics perspective on the treatment of paediatric obesity. The results detail recently published research findings on the cost-effectiveness of paediatric obesity treatments and identify key characteristics of cost-effective interventions. METHODS: A structured search was applied to six databases with no data restriction through March 2023: Medline, Embase, Cochrane CENTRAL, CINAHL, and PsycINFO. Studies that included a cost analysis of an individual level, weight management intervention (behavioural, pharmacotherapy, and surgical) in youth, with obesity, ages 2 to 21 years were eligible for inclusion. RESULTS: Of the 4371 records identified in the initial search, 353 underwent full-text review, 39 studies met the pre-specified inclusion criteria. The majority were published after 2010 (n = 36/39, 92%) and applied to high-income countries (n = 39/39, 100%). Thirty-five of the studies assessed the cost-effectiveness of lifestyle interventions (90%), and four studies assessed surgical outcomes (10%). No pharmacotherapy studies met eligibility criteria. Although the outcome measures differed across the studies, all four surgical interventions were reported to be cost-effective. Thirty of the 35 (85%) lifestyle modification studies were reported to be cost-effective compared to the study comparator examined. CONCLUSIONS: There is a small amount of evidence that individual-level paediatric obesity treatment interventions are cost-effective and, in some cases cost-saving, with most of this work conducted on behavioural interventions. The economic evaluation of paediatric obesity interventions poses various methodologic challenges, which should be addressed in future research to fully use the potential of economic evaluation as an aid to decision-making

Diagnostic accuracy of haemophilia early arthropathy detection with ultrasound (HEAD-US): A comparative magnetic resonance imaging (MRI) study

Background. Repeated haemarthroses affect approximately 90% of patients with severe haemophilia and lead to progressive arthropathy, which is the main cause of morbidity in these patients. Diagnostic imaging can detect even subclinical arthropathy changes and may impact prophylactic treatment. Magnetic resonance imagining (MRI) is generally the gold standard tool for precise evaluation of joints, but it is not easily feasible in regular follow-up of patients with haemophilia. The development of the standardized ultrasound (US) protocol for detection of early changes in haemophilic arthropathy (HEAD-US) opened new perspectives in the use of US in management of these patients. The HEAD-US protocol enables quick evaluation of the six mostly affected joints in a single study. The aim of this prospective study was to determine the diagnostic accuracy of the HEAD-US protocol for the detection and quantification of haemophilic arthropathy in comparison to the MRI. Patients and methods. The study included 30 patients with severe haemophilia. We evaluated their elbows, ankles and knees (overall 168 joints) by US using the HEAD-US protocol and compared the results with the MRI using the International Prophylaxis Study Group (IPSG) MRI score. Results. The results showed that the overall HEAD-US score correlated very highly with the overall IPSG MRI score (r = 0.92). Correlation was very high for the evaluation of the elbows and knees (r 48 0.95), and slightly lower for the ankles (r 48 0.85). Conclusions. HEAD-US protocol proved to be a quick, reliable and accurate method for the detection and quantification of haemophilic arthropathy

Mir-96 and miR-183 differentially regulate neonatal and adult post-infarct neovascularisation

Following myocardial infarction (MI), the adult heart has minimal regenerative potential. Conversely, the neonatal heart can undergo extensive regeneration, and neovascularisation capacity was hypothesised to contribute to this difference. Here, we demonstrate the higher angiogenic potential of neonatal compared to adult mouse cardiac endothelial cells (MCECs) in vitro and use this difference to identify candidate microRNAs (miRs) regulating cardiac angiogenesis after MI. MiR expression profiling revealed miR-96 and miR-183 upregulation in adult compared to neonatal MCECs. Their overexpression decreased the angiogenic potential of neonatal MCECs in vitro and prevented scar resolution and neovascularisation in neonatal mice after MI. Inversely, their inhibition improved the angiogenic potential of adult MCECs, and miR-96/miR-183 knock-out mice had increased peri-infarct neovascularisation. In silico analyses identified anillin (ANLN) as a direct target of miR-96 and miR-183. In agreement, Anln expression declined following their overexpression and increased after their inhibition in vitro. Moreover, ANLN expression inversely correlated with miR-96 expression and age in cardiac ECs of cardiovascular patients. In vivo, ANLN-positive vessels were enriched in the peri-infarct area of miR-96/miR-183 knock-out mice. These findings identify miR-96 and miR-183 as regulators of neovascularisation following MI and miR-regulated genes such as anillin as potential therapeutic targets for cardiovascular disease

Erratum to: Methods for evaluating medical tests and biomarkers

[This corrects the article DOI: 10.1186/s41512-016-0001-y.]