966 research outputs found

    Common hypercyclic vectors for families of operators

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    We provide a criterion for the existence of a residual set of common hypercyclic vectors for an uncountable family of hypercyclic operators which is based on a previous one given by Costakis and Sambarino. As an application, we get common hypercyclic vectors for a particular family of hypercyclic scalar multiples of the adjoint of a multiplier in the Hardy space, generalizing recent results by Abakumov and Gordon and also Bayart. The criterion is applied to other specific families of operators

    Shrub facilitation increases plant diversity along an arid scrubland-temperate rainforest boundary in South America

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    Theoretical models predict nurse plant facilitation enhances species richness by ameliorating stressful environmental conditions and expanding distributional ranges of stress-intolerant species into harsh environments. We studied the role of nurse facilitation on the recruitment of perennial plants along an arid scrubland–temperate rain forest boundary to test the following predictions: (1) nurse shrub canopy increases seedling abundance and species richness along the rain forest–scrubland boundary; (2) scrubland species are less dependent on facilitative interactions than temperate rain forest species, especially at the moister, upper end of the gradient

    Clinical microbiological case: sore throat and painful bilateral lymph nodes

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    Thermo-economic analysis of an oxygen production plant powered by an innovative energy recovery system

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    [EN] Oxy-fuel combustion is considered an attractive alternative to reduce pollutant emissions, which uses high-purity oxygen mixed instead of air for combustion processes. However, purchasing large amounts of high-purity oxygen may be unprofitable for certain industrial sectors, discouraging its implementation. Considering this, the potential of an oxygen production cycle for factories using oxy-fuel combustion is studied by performing a thermo-economic analysis where high-purity oxygen, electricity, and natural gas prices are considered. Oxygen is produced by membrane means, where mixed ionic-electronic conducting membranes are used, which require high temperatures and pressure gradients to work properly. A set of turbochargers is implemented, chosen by scaling an off-the-shelf model, what introduces an innovative way of waste energy recovering for improving the performance of the cycle. The whole cycle is powered by waste heat from high temperature flue gases, and it is sized for a ceramic manufacturing factory. In this work, two cases are analysed, differentiated by considering additional heating and the vacuum generation method in the oxygen line. The first case exhibits smaller production levels, although better profitability (31¿€t¿1), whereas the second case displays higher production levels and production costs (33¿€t¿1). Both cases are competitive concerning the average price of high-purity oxygen, supposing an average of 50¿€t¿1 in wholesale markets, proving the potential of the proposed alternative for oxygen production.This research work has been supported by Grant PDC2021120821-I00 funded by MCIN/AEI/10.13039/501100011033 and by European Union NextGenerationEU/PRTR. This work has also been supported by Grant UPV-SOLGEN-79674 funded by the Vicerrectorado de Investigacion de la Universitat Politecnica de Valencia (PAID-11-21). The authors want to acknowledge the institution "Conselleria d'Educacio, Investigaci o, Cultura i Esport de la Generalitat Valenciana" and its grant program "Subvenciones para la contratacion de personal investigador de caracter predoctoral" for doctoral studies (ACIF/2020/246) funded by The European Union. Also, this work is part of grant number INNVA1/2021/38 funded by "Agencia Valenciana de la Innovacion (AVI)" and by "ERDF A way of making Europe".Serrano, J.; Arnau Martínez, FJ.; García-Cuevas González, LM.; Gutierrez, FA. (2022). Thermo-economic analysis of an oxygen production plant powered by an innovative energy recovery system. Energy. 255:1-18. https://doi.org/10.1016/j.energy.2022.12441911825

    Correlates of ideal cardiovascular health in European adolescents: The HELENA study

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    Background and aims: The ideal cardiovascular health (iCVH) construct consists of 4 health behaviors (smoking status, body mass index, physical activity and diet) and 3 health factors (total cholesterol, blood pressure and fasting glucose). A greater number of iCVH components in adolescence are related to better cardiovascular health, but little is known about the correlates of iCVH in adolescents. Thus, the aim of the study was to examine correlates of iCVH in European adolescents. Methods and results: The study comprised 637 European adolescents with complete iCVH data. Participants were part of the Healthy Lifestyle in Europe by Nutrition in Adolescence (HELENA) study, a cross-sectional, multicenter study conducted in 9 different European countries. Correlates investigated were sex and age, family affluence scale, maternal education, geographic location, sleep time, television viewing, duration of pregnancy, birth weight and breastfeeding. Younger adolescents, those whose mothers had medium/high education or those whowatched television less than 2 h per day had a greater number of iCVH components compared to those who were older, had a mother with low education or watched television 2 h or more daily (P <= 0.01). Conclusion: Since in our study older adolescents had worse iCVH than younger adolescents, early promotion of cardiovascular health may be important. Future studies mayalso investigate the usefulness of limiting television viewing to promote iCVH. Finally, since adolescents of mothers with low education had poorer iCVH, it may be of special interest to tailor public health promotion to adolescents from families with low socioeconomic status

    Prediction of Pathological Tremor Signals Using Long Short-Term Memory Neural Networks

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    Previous implementations of closed-loop peripheral electrical stimulation (PES) strategies have provided evidence about the effect of the stimulation timing on tremor reduction. However, these strategies have used traditional signal processing techniques that only consider phase prediction and might not model the non-stationary behavior of tremor. Here, we tested the use of long short-term memory (LSTM) neural networks to predict tremor signals using kinematic data recorded from Essential Tremor (ET) patients. A dataset comprising wrist flexion-extension data from 12 ET patients was pre-processed to feed the predictors. A total of 180 models resulting from the combination of network (neurons and layers of the LSTM networks, length of the input sequence and prediction horizon) and training parameters (learning rate) were trained, validated and tested. Predicted tremor signals using LSTM-based models presented high correlation values (from 0.709 to 0.998) with the expected values, with a phase delay between the predicted and real signals below 15 ms, which corresponds approximately to 7.5% of a tremor cycle. The prediction horizon was the parameter with a higher impact on the prediction performance. The proposed LSTM-based models were capable of predicting both phase and amplitude of tremor signals outperforming results from previous studies (32 - 56% decreased phase prediction error compared to the out-of-phase method), which might provide a more robust PES-based closed-loop control applied to PES-based tremor reduction.The authors would like to thank Cristina Montero Pardo for illustrations from Fig. 1 and the patients from Gregorio Marañón Hospital who voluntarily participated in this study

    Pulmonary long-term consequences of COVID-19 infections after hospital discharge

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    Objectives: COVID-19 survivors are reporting residual abnormalities after discharge from the hospital. Limited information is available about this stage of recovery or the lingering effects of the virus on pulmonary function and inflammation. The aim of this study was to describe lung function and to identify biomarkers in serum and induced sputum samples from patients recovering from COVID-19 hospitalisation. Methods: Patients admitted to Spanish hospitals with laboratory-confirmed COVID-19 infection by a real-time PCR (RT-PCR) assay for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) were recruited for this study. Each hospital screened their lists of discharged patients at least 45 days after symptom onset. SARS-CoV-2-infected patients were divided into mild/moderate and severe disease groups according to the severity of their symptoms during hospitalisation. Patients’ epidemiological and medical histories, comorbidities, chronic treatments, and laboratory parameters were evaluated. Pulmonary function tests, the standardised 6-minute walk test (6 MWT) and chest computed tomography (CT) were also performed. The levels of proteases, their inhibitors, and shed receptors were measured in serum and induced sputum samples. Results: A total of 100 patients with respiratory function tests were included in this study. The median number of days after the onset of symptoms was 104 (IQR 89.25, 126.75). COVID-19 was severe in 47% (47/100) of patients. CT was normal in 48% (48/100) of patients. Lung function was normal (FEV1 ≥80%, FVC ≥80%, FEV1/FVC ≥0.7, and diffusing capacity for carbon monoxide [DLCO] ≥80%) in 92% (92/100), 94% (94/100), 100% (100/100) and 48% (48/100) of patients, respectively. Multivariate analysis showed that a DLCO <80% (OR 5.92; 95%CI 2.28-15.37; p <0.0001) and a lower serum LDH level (OR 0.98; 95%CI 0.97-0.99) were associated with the severe disease group of SARS-CoV-2 during hospital stay. Conclusions: A diffusion deficit (DLCO <80%) was still present after hospital discharge and was associated with the most severe SARS-CoV-2 cases

    Green function techniques in the treatment of quantum transport at the molecular scale

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    The theoretical investigation of charge (and spin) transport at nanometer length scales requires the use of advanced and powerful techniques able to deal with the dynamical properties of the relevant physical systems, to explicitly include out-of-equilibrium situations typical for electrical/heat transport as well as to take into account interaction effects in a systematic way. Equilibrium Green function techniques and their extension to non-equilibrium situations via the Keldysh formalism build one of the pillars of current state-of-the-art approaches to quantum transport which have been implemented in both model Hamiltonian formulations and first-principle methodologies. We offer a tutorial overview of the applications of Green functions to deal with some fundamental aspects of charge transport at the nanoscale, mainly focusing on applications to model Hamiltonian formulations.Comment: Tutorial review, LaTeX, 129 pages, 41 figures, 300 references, submitted to Springer series "Lecture Notes in Physics

    Management and outcomes of patients with left atrial appendage thrombus prior to percutaneous closure

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    Altres ajuts: Fundación Interhospitalaria para la Investigación Cardiovascular (FIC Foundation); Abbott.Objective: Left atrial appendage (LAA) thrombus has heretofore been considered a contraindication to percutaneous LAA closure (LAAC). Data regarding its management are very limited. The aim of this study was to analyse the medical and invasive treatment of patients referred for LAAC in the presence of LAA thrombus. Methods: This multicentre observational registry included 126 consecutive patients referred for LAAC with LAA thrombus on preprocedural imaging. Treatment strategies included intensification of antithrombotic therapy (IAT) or direct LAAC. The primary and secondary endpoints were a composite of bleeding, stroke and death at 18 months, and procedural success, respectively. Results: IAT was the preferred strategy in 57.9% of patients, with total thrombus resolution observed in 60.3% and 75.3% after initial and subsequent IAT, respectively. Bleeding complications and stroke during IAT occurred in 9.6% and 2.9%, respectively, compared with 3.8% bleeding and no embolic events in the direct LAAC group before the procedure. Procedural success was 90.5% (96.2% vs 86.3% in direct LAAC and IAT group, respectively, p=0.072), without cases of in-hospital thromboembolic complications. The primary endpoint occurred in 29.3% and device-related thrombosis was found in 12.8%, without significant difference according to treatment strategy. Bleeding complications at 18 months occurred in 22.5% vs 10.5% in the IAT and direct LAAC group, respectively (p=0.102). Conclusion: In the presence of LAA thrombus, IAT was the initial management strategy in half of our cohort, with initial thrombus resolution in 60% of these, but with a relatively high bleeding rate (∼10%). Direct LAAC was feasible, with high procedural success and absence of periprocedural embolic complications. However, a high rate of device-related thrombosis was detected during follow-up
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