1,151 research outputs found

    Intruder States and their Local Effect on Spectral Statistics

    Full text link
    The effect on spectral statistics and on the revival probability of intruder states in a random background is analysed numerically and with perturbative methods. For random coupling the intruder does not affect the GOE spectral statistics of the background significantly, while a constant coupling causes very strong correlations at short range with a fourth power dependence of the spectral two-point function at the origin.The revival probability is significantly depressed for constant coupling as compared to random coupling.Comment: 18 pages, 10 Postscript figure

    Data-driven estimation of the instantaneous reproduction number and growth rates for the 2022 monkeypox outbreak in Europe

    Get PDF
    Objective: To estimate the instantaneous reproduction number RtR_t and the epidemic growth rates for the 2022 monkeypox outbreaks in the European region. Methods: We gathered daily laboratory-confirmed monkeypox cases in the most affected European countries from the beginning of the outbreak to September 23, 2022. A data-driven estimation of the instantaneous reproduction number is obtained using a novel filtering type Bayesian inference. A phenomenological growth model coupled with a Bayesian sequential approach to update forecasts over time is used to obtain time-dependent growth rates in several countries. Results: The instantaneous reproduction number RtR_t for the laboratory-confirmed monkeypox cases in Spain, France, Germany, the UK, the Netherlands, Portugal, and Italy. At the early phase of the outbreak, our estimation for RtR_t, which can be used as a proxy for the basic reproduction number R0R_0, was 2.062.06 (95%95\% CI 1.63−2.541.63-2.54) for Spain, 2.622.62 (95%95\% CI 2.23−3.172.23-3.17) for France, 2.812.81 (95%95\% CI 2.51−3.092.51-3.09) for Germany, 1.821.82 (95%95\% CI 1.52−2.181.52-2.18) for the UK, 2.842.84 (95%95\% CI 2.07−3.912.07-3.91) for the Netherlands, 1.131.13 (95%95\% CI 0.99−1.320.99-1.32) for Portugal, 3.063.06 (95%95\% CI 2.48−3.622.48-3.62) for Italy. Cumulative cases for these countries present subexponential rather than exponential growth dynamics. Conclusions: Our findings suggest that the current monkeypox outbreaks present limited transmission chains of human-to-human secondary infection so the possibility of a huge pandemic is very low. Confirmed monkeypox cases are decreasing significantly in the European region, the decline might be attributed to public health interventions and behavioral changes in the population due to increased risk perception. Nevertheless, further strategies toward elimination are essential to avoid the subsequent evolution of the monkeypox virus that can result in new outbreaks.Non

    The erosion of nongambling spheres by smartphone gambling: a qualitative study on workplace and domestic disordered gambling

    Get PDF
    The potential dangers of internet-based gambling as compared with more traditional land-based gambling have been increasingly investigated over the past decade. The general consensus appears to be that although internet gambling might not be a more dangerous medium for gambling per se, the 24/7 availability it generates for problem gamblers, however, is. Because smartphones have become the most used way of gambling online, internet gambling must, therefore, be further subcategorized according to the device by which it is accessed. This study examines the issue by exploring the views of smartphone gamblers undergoing treatment for gambling disorder in focus group settings (N=35). Utilizing thematic analysis, the paper shows that smartphone gambling has colonized spaces previously regarded as nongambling spheres. The workplace, especially in male-dominated contexts, emerged as an accommodator and stimulator of gambling behavior, raising issues of productivity rather than criminality. Domestic gambling was mostly characterized by an invasion of bathroom and bedtime spheres of intimacy. The study examines the implications of prevention and treatment, focusing on the minimization of exposure to gambling stimuli, the erosion of intimacy that recovering gamblers must endure, and the necessity of embracing a broader definition of gambling-related harm

    Strategic Teaching Plan For The Training of Students Towards. The Creation and Management of Family Businesses in Barcelona, Spain

    Get PDF
    Family businesses are one of the main drivers of the economy, hence the relevance of studying them. There are several contributions from national specialists on the subject of family businesses, but the studies and tools developed with the purpose of to professionalize to this type of companies are insufficient. Therefore, the main objective of this research is to design a strategic teaching plan with interdisciplinary characteristics for the training of students towards the creation and management of family businesses in Barcelona, Spain, responding to the needs and demands of society. The methodology used is of a quantitative nature, with a scope according to the level of knowledge obtained with said research: exploratory-descriptive. It also required a non-experimental descriptive transactional type, all in order to investigate the incidence and provide a vision of the study community. The unit of analysis used was the teaching staff of the area of Organization of companies. Based on the proposed strategic teaching plan, it is intended that teachers first acquire the same skills that students are required to manage and lead family businesses. Key words: strategic plan, family businesses, teaching competencies JEL Classification: M13, M19, M53, M5

    Optimal vaccine allocation for the control of sexually transmitted infections

    Get PDF
    The burden of sexually transmitted infections (STIs) poses a challenge due to its large negative impact on sexual and reproductive health worldwide. Besides simple prevention measures and available treatment efforts, prophylactic vaccination is a powerful tool for controlling some viral STIs and their associated diseases. Here, we investigate how prophylactic vaccines are best distributed to prevent and control STIs. We consider sex-specific differences in susceptibility to infection, as well as disease severity outcomes. Different vaccination strategies are compared assuming distinct budget constraints that mimic a scarce vaccine stockpile. Vaccination strategies are obtained as solutions to an optimal control problem subject to a two-sex Kermack– McKendrick-type model, where the control variables are the daily vaccination rates for females and males. One important aspect of our approach relies on conceptualizing a limited but specific vaccine stockpile via an isoperimetric constraint. We solve the optimal control problem via Pontryagin’sMaximum Principle and obtain a numerical approximation for the solution using a modified version of the forward–backward sweep method that handles the isoperimetric budget constraint in our formulation. The results suggest that for a limited vaccine supply (20%–30%vaccination coverage), onesex vaccination, prioritizing females, appears to be more beneficial than the inclusion of both sexes into the vaccination program.Whereas, if the vaccine supply is relatively large (enough to reach at least 40% coverage), vaccinating both sexes, with a slightly higher rate for females, is optimal and provides an effective and faster approach to reducing the prevalence of the infection

    Optimal vaccination strategies for a heterogenous population using multiple objectives: The case of L1 and L2-formulations

    Get PDF
    The choice of the objective functional in optimization problems coming from biomedical and epidemiological applications plays a key role in optimal control outcomes. In this study, we investigate the role of the objective functional on the structure of the optimal control solution for an epidemic model for sexually transmitted infections that includes a core group with higher sexual activity levels than the rest of the population. An optimal control problem is formulated to find a targeted vaccination program able to control the spread of the infection with minimum vaccine deployment. Both L1−L_{1}- and L2−L_{2}-objectives are considered as an attempt to explore the trade-offs between control dynamics and the functional form characterizing optimality. The results show that the optimal vaccination policies for both the L1−L_{1}- and the L2−L_{2}-formulation share one important qualitative property, that is, immunization of the core group should be prioritized by policymakers to achieve a fast reduction of the epidemic. However, quantitative aspects of this result can be significantly affected depending on the choice of the control weights between formulations. Overall, the results suggest that with appropriate weight constants, the optimal control outcomes are reasonably robust with respect to the L1−L_{1}- or L2−L_{2}-formulation. This is particularly true when the monetary cost of the control policy is substantially lower than the cost associated with the disease burden. Under these conditions, even if the L1−L_{1}-formulation is more realistic from a modeling perspective, the L2−L_{2}-formulation can be used as an approximation and yield qualitatively comparable outcomes

    In-situ monitoring by thermal lens microscopy of a photocatalytic reduction process of hexavalent chromium

    Get PDF
    In this work, we describe the application of a micro-spatial thermal lens spectroscopy setup (thermal lens microscope, TLM) with coaxial counter-propagating pump, and probe laser beams, and an integrated passive optical Fabry-Perot, to quantify the Cr-VI concentration in water during a photocatalytic reaction in-situ. A series of test samples was analyzed using the 1.5 diphenil carbazide colorimetric method. A calibration curve was obtained by plotting of the TLM signal as a function of the concentration of Cr(VI) in a range between 0 and 10 mu g/L (1 mu g/L = 1 ppb, part per billion), with a detection limit of 53 ng/L (1 ng/L = 1 ppt, part per trillion). A solution of 10 mu g/L Cr(VI) in distillated water was placed into a cell in contact with an iron-incorporated titanium dioxide film, which was previously grown onto a 1 mm thick glass microscope slide by the sol-gel dip-coating technique. The TLM signal was registered as a function of the photocatalysis time measured from the beginning of the process, radiating the film with UV-violet light. The Cr(VI) concentration was determined with the calibration curve and after the first 50 minutes a reduction of 95 % of Cr(VI) was observed, being the chemical reaction kinetic described by a potential time decreasing function.645507511Agências de fomento estrangeiras apoiaram essa pesquisa, mais informações acesse artig
    • …
    corecore