62 research outputs found

    Diferencias de género en la percepción y valoración del dolor y de la dimensión emocional tras un programa de ejercicios en adultos

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    En el análisis de las posibles relaciones entre el dolor y la dimensión emocional (DE), algunos autores como Casado y Urbano (2001) afirman que los pacientes con dolor continuo presentan un mayor grado de ansiedad y depresión que los pacientes con dolor intermitente. Otros investigadores analizan las diferencias de género en relación a la tolerancia al dolor (Bircan, 2007; Puddifoot, 2007) y la calidad de vida (Seculí, 2001; Vilagut, 2005). Por ello, nos planteamos analizar las diferencias de género tras un programa de Natación Terapéutica (PNT) en las variables dolor, medido mediante la Escala Visual Analógica y, en la DE cuya valoración se ha realizado mediante un cuestionario elaborado a tal efecto (EDAQ-9). Hemos realizado un estudio expostfacto comparativo causal con postest y pretest retrospectivo en 52 sujetos. Posteriormente, realizamos un análisis de los datos mediante técnicas descriptivas, correlaciones y de contraste aplicando estudios exploratorios mediante descriptores robustos en función del género. El estudio demuestra que existen diferencias significativas en las variables estudiadas en función del género: las mujeres experimentan más dolor y una DE más marcada, antes y después de la realización del PNT

    El poder de las naciones en la Unión Europea

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    En este trabajo se definen algoritmos, basados en funciones generatrices, para calcular el índice de poder de Banzhaf en juegos simples de votación ponderada y en juegos de doble y triple mayoría. La utilización de funciones generatrices permite un cálculo exacto del índice de Banzhaf con una reducción sensible de la complejidad temporal. Además se calculan los índices de Banzhaf para las reglas de decisión, aprobadas en la cumbre de Niza, que se utilizan en la Unión Europea ampliada a 25 países. Finalmente, se demuestra que los sistemas de triple mayoría adoptados son equivalentes en la práctica a juegos de mayoría simple o doble, porque la cuota de población exigida para aprobar una decisión no cambia el índice de Banzhaf de los países de la Unión Europea ampliada.Juegos de votación; índice de Banzhaf; Unión Europea

    An accurate density functional theory for the vaporliquid interface of chain molecules based on the statistical associating fluid theory for potentials of variable range for Mie chainlike fluids

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    A new Helmholtz free energy density functional is presented to predict the vapor-liquid interface of chainlike molecules. The functional is based on the last version of the statistical associating fluid theory for potentials of variable range for homogeneous Mie chainlike fluids (SAFT-VR Mie). Following the standard formalism, the density functional theory (SAFT-VR Mie DFT) is constructed using a perturbative approach in which the free energy density contains a reference term to describe all the short-range interactions treated at the local level, and a perturbative contribution to account for the attractive perturbation which incorporates the long-range dispersive interactions. In this first work, we use a mean-field version of the theory in which the pair correlations are neglected in the attractive term. The SAFT-VR Mie DFT formalism is used to examine the effect of molecular chain length and the repulsive exponent of the intermolecular potential on density profiles and surface tension of linear chains made up to six Mie (lr6) segments with different values of the repulsive exponent of the intermolecular potential. Theoretical predictions from the theory are compared directly with molecular simulation data for density profiles and surface tension of Mie chainlike molecules taken from the literature. Agreement between theory and simulation data is good for short-chain molecules at all thermodynamic conditions of coexistence considered. Once the theory has proven that is able to predict the interfacial properties, and particularly interfacial tension, the SAFT-VR Mie DFT formalism is used to predict the interfacial behavior of two new coarse-grained models for carbon dioxide and water recently proposed in the literature. In particular, the theoretical formalism, in combination with the coarse-grained models for carbon dioxide and water, is able to predict the interfacial properties of these important substances in a reasonable way.The authors thank helpful discussions with Carlos Avendaño andJosé Matías Garrido. We also acknowledge Centro de Supercom-putación de Galicia (CESGA, Santiago de Compostela, Spain) andMCIA (Mésocentre de Calcul Intensif Aquitain) of the Universitésde Bordeaux and Pau et Pays de l’Adour (France), for providingaccess to computing facilities and Ministerio de Economía, In-dustria y Competitividad through Grant with reference FIS2017-89361-C3-1-P co-financed by EU FEDER funds. Further financialsupport from Junta de Andalucía and Universidad de Huelva isalso acknowledged. J.A., J.M.M., and F.J.B. thankfully acknowl-edge the computer resources at Magerit and the technical supportprovided by the Spanish Supercomputing Network (RES) (ProjectQCM-2018-2-0042)

    Simulation of the carbon dioxide hydrate-water interfacial energy

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    Hypothesis: Carbon dioxide hydrates are ice-like nonstoichiometric inclusion solid compounds with importance to global climate change, and gas transportation and storage. The thermodynamic and kinetic mechanisms that control carbon dioxide nucleation critically depend on hydrate-water interfacial free energy. Only two independent indirect experiments are available in the literature. Interfacial energies show large uncertainties due to the conditions at which experiments are performed. Under these circumstances, we hypothesize that accurate molecular models for water and carbon dioxide combined with computer simulation tools can offer an alternative but complementary way to estimate interfacial energies at coexistence conditions from a molecular perspective. Calculations: We have evaluated the interfacial free energy of carbon dioxide hydrates at coexistence conditions (three-phase equilibrium or dissociation line) implementing advanced computational methodologies, including the novel Mold Integration methodology. Our calculations are based on the definition of the interfacial free energy, standard statistical thermodynamic techniques, and the use of the most reliable and used molecular models for water (TIP4P/Ice) and carbon dioxide (TraPPE) available in the literature. Findings: We find that simulations provide an interfacial energy value, at coexistence conditions, consistent with the experiments from its thermodynamic definition. Our calculations are reliable since are based on the use of two molecular models that accurately predict: (1) The ice-water interfacial free energy; and (2) the dissociation line of carbon dioxide hydrates. Computer simulation predictions provide alternative but reliable estimates of the carbon dioxide interfacial energy. Our pioneering work demonstrates that is possible to predict interfacial energies of hydrates from a truly computational molecular perspective and opens a new door to the determination of free energies of hydrates.We thank Pedro J. Pérez for the critical reading of the manuscript. We also acknowledge Centro de Supercomputación de Galicia (CESGA, Santiago de Compostela, Spain) and MCIA (Mésocentre de Calcul Intensif Aquitain) of the Universités de Bordeaux and Pau et Pays de l’Adour (France) for providing access to computing facilities. We thank financial support from the Ministerio de Economía, Industria y Competitividad (FIS2017- 89361-C3-1-P), Junta de Andalucía (P20-00363), and Universidad de Huelva (P.O. FEDER UHU-1255522), all three cofinanced by EU FEDER funds. J.A. acknowledges Contrato Predoctoral de Investigación from XIX Plan Propio de Investigación de la Universidad de Huelva and a FPU Grant (Ref. FPU15/03754) from Ministerio de Educación, Cultura y Deporte. J. A., J. M. M., and F. J. B. thankfully acknowledge the computer resources at Magerit and the technical support provided by the Spanish Supercomputing Network (RES) (Project QCM- 2018–2- 0042). Funding for open access charge: Universidad de Huelva / CBU

    Vapour–liquid phase equilibria and interfacial properties of fatty acid methyl esters from molecular dynamics simulations

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    We have determined the phase equilibria and interfacial properties of a methyl ester homologous series (from methyl acetate to methyl heptanoate) using direct simulations of the vapour–liquid interfaces. The methyl esters are modelled using the united atom approach in combination with transferable parameters for phase equilibria (TraPPE) force fields for alkanes, alkenes, carbon dioxide, ethers, and carboxylic acids in a transferable way. This allows us to take into account explicitly both dispersive and coulombic inter- actions, as well as the repulsive Pauli-exclusion interactions. Simulations are performed in the NVT or canonical ensemble using molecular dynamics. Vapour–liquid surface tension is determined using the virial route, i.e., evaluating the normal and tangential components of the pressure tensor along the simu- lation box. We have also calculated density profiles, coexistence densities, vapour pressures, surface entropies and enthalpies, and interfacial thickness as functions of temperature, as well as the normal boiling temperatures and the critical temperatures, densities, and pressures for each member of the series. Special attention is paid to the comparison between experimental data taken from the literature and our results obtained using molecular dynamics simulations. We also analyze the effect of increasing the molecular weight of the methyl esters (at fixed temperature) on all the properties considered, with special emphasis on phase equilibria envelopes and surface tension. The TraPPE force fields transferred from other molecules and chemical families are able to predict very accurately the experimental vapour–liquid phase envelopes of methyl esters. We also compare the results obtained from simulations of the surface tension, with experimental data taken from the literature. To our knowledge, this is the first time that vapour–liquid phase equilibria and interfacial properties, and particularly surface tension, of this methyl ester homologous series are obtained using computer simulation.The authors acknowledge the Centro de Supercomputación de Galicia (CESGA, Santiago de Compostela, Spain) for providing access to computing facilities, and Ministerio de Economía, Industria y Competitividad through the Grant with reference FIS2017-89361-C3-1-P co-financed by EU FEDER funds. A. M. acknowledges funding from Fondecyt (Chile) through Grant 1190107. Further financial support from Junta de Andalucía and Universidad de Huelva is also acknowledged. J. A. F. acknowledges Contrato Predoctoral de Investigación from XIX Plan Propio de Investigación de la Universidad de Huelva and an FPU Grant (Ref. FPU15/03754) from the Ministerio de Educación, Cultura y Deporte. J. A., J. M. M., P. G.-A., and F. J. B. thankfully acknowledge the computer resources at Magerit and the technical support provided by the Spanish Supercomputing Network (RES) (Project QCM-2018-2-0042)

    Understanding the Phase Behavior of Tetrahydrofuran + Carbon Dioxide, + Methane, and + Water Binary Mixtures from the SAFT-VR Approach

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    The high-pressure phase diagrams of the tetrahydrofuran(1) + carbon dioxide(2), + methane(2), and + water(2) mixtures are examined using the SAFT-VR approach. Carbon dioxide molecule is modeled as two spherical segments tangentially bonded, water is modeled as a spherical segment with four associating sites to represent the hydrogen bonding, methane is represented as an isolated sphere, and tetrahydrofuran is represented as a chain of m tangentially bonded spherical segments. Dispersive interactions are modeled using the square-well intermolecular potential. In addition, two different molecular model mixtures are developed to take into account the subtle balance between water−tetrahydrofuran hydrogen-bonding interactions. The polar and quadrupolar interactions present in water, tetrahydrofuran, and carbon dioxide are treated in an effective way via square-well potentials of variable range. The optimized intermolecular parameters are taken from the works of Giner et al. (Fluid Phase Equil. 2007, 255, 200), Galindo and Blas (J. Phys. Chem. B 2002, 106, 4503), Patel et al (Ind. Eng. Chem. Res. 2003, 42, 3809), and Clark et al. (Mol. Phys. 2006, 104, 3561) for tetrahydrofuran, carbon dioxide, methane, and water, respectively. The phase diagrams of the binary mixtures exhibit different types of phase behavior according to the classification of van Konynenburg and Scott, ranging from types I, III, and VI phase behavior for the tetrahydrofuran(1) + carbon dioxide(2), + methane(2), and + water(2) binary mixtures, respectively. This last type is characterized by the presence of a Bancroft point, positive azeotropy, and the so-called closed-loop curves that represent regions of liquid−liquid immiscibility in the phase diagram. The system exhibits lower critical solution temperatures (LCSTs), which denote the lower limit of immiscibility together with upper critical solution temperatures (UCSTs). This behavior is explained in terms of competition between the incompatibility with the alkyl parts of the tetrahydrofuran ring chain and the hydrogen bonding between water and the ether group. A minimum number of unlike interaction parameters are fitted to give the optimal representation of the most representative features of the binary phase diagrams. In the particular case of tetrahydrofuran(1) + water(2), two sets of intermolecular potential model parameters are proposed to describe accurately either the hypercritical point associated with the closed-loop liquid−liquid immiscibility region or the location of the mixture lower- and upper-critical end-points. The theory is not only able to predict the type of phase behavior of each mixture, but also provides a reasonably good description of the global phase behavior whenever experimental data are available.We acknowledge Ministerio de Economía y Competitividad of Spain for financial support from Projects FIS2012-33621 and FIS2015-68910-P (M.M.P. and J.M.M.) and FIS2013-46920- C2-1-P (F.J.B. and J.A.), both cofinanced with EU Feder funds. J.M.M. acknowledges Xunta de Galicia for a Postdoctoral Grant (ED481B2014/117-0). The French CARNOT Institute ISIFoR is also acknowledged for the funds provided through the THEMYS Project (novel approaches in thermodynamical modelling and molecular simulation for the study of gas hydrates and their applications). Further financial support from Universidad de Huelva and Junta de Andalucía is also acknowledged

    High prevalence of obstructive sleep apnea syndrome in Spain’s Stroke Belt

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    [Objective] Spain’s so-called Stroke Belt is an area with high prevalence of vascular disease. We aimed to determine the prevalence of undetected obstructive sleep apnea–hypopnea syndrome (OSAHS) among patients with acute ischemic stroke (AIS) in southern Spain.[Methods] We conducted a cross-sectional study at the Virgen Macarena University Hospital Stroke Unit during 2018 to 2019. We included patients <72 hours after AIS with a neuroimaging lesion and performed sleep tests.[Results] Seventy-two patients were included. The median participant age was 72 years. Mean body mass index was 27.07 kg/m2, and 40.28% were daily alcohol drinkers. Hypertension, atrial fibrillation, ischemic cardiomyopathy, and previous stroke were detected in 63.9%, 11.1%, 15.3%, and 17.6% of patients, respectively. Polygraphy was feasible in 91.38% of patients. The prevalence of OSAHS was 84.72% (apnea–hypopnea index ≥5). Patients with moderate and severe OSAHS were more likely to be obese and to have a larger neck circumference and facial palsy. The diagnostic criteria of central sleep apnea syndrome were met in only 1.38% of patients.[Conclusions] The high prevalence of OSAHS found in the Spanish Stroke Belt justifies further investigation and development of a screening program as a strategy to identify patients with undetected OSAHS.The authors disclosed receipt of the following financial support for the research, authorship and/or publication of this article: This work was supported by the Neurovascular Research Group, part of the Cooperative Cerebrovascular Disease Research Network (INVICTUS+) (RD16/0019/0015).Peer reviewe

    Solubility of Methane in Water: Some Useful Results for Hydrate Nucleation

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    In this paper, the solubility of methane in water along the 400 bar isobar is determined by computer simulations using the TIP4P/Ice force field for water and a simple LJ model for methane. In particular, the solubility of methane in water when in contact with the gas phase and the solubility of methane in water when in contact with the hydrate has been determined. The solubility of methane in a gas–liquid system decreases as temperature increases. The solubility of methane in a hydrate–liquid system increases with temperature. The two curves intersect at a certain temperature that determines the triple point T3 at a certain pressure. We also determined T3 by the three-phase direct coexistence method. The results of both methods agree, and we suggest 295(2) K as the value of T3 for this system. We also analyzed the impact of curvature on the solubility of methane in water. We found that the presence of curvature increases the solubility in both the gas–liquid and hydrate–liquid systems. The change in chemical potential for the formation of hydrate is evaluated along the isobar using two different thermodynamic routes, obtaining good agreement between them. It is shown that the driving force for hydrate nucleation under experimental conditions is higher than that for the formation of pure ice when compared at the same supercooling. We also show that supersaturation (i.e., concentrations above those of the planar interface) increases the driving force for nucleation dramatically. The effect of bubbles can be equivalent to that of an additional supercooling of about 20 K. Having highly supersaturated homogeneous solutions makes possible the spontaneous formation of the hydrate at temperatures as high as 285 K (i.e., 10K below T3). The crucial role of the concentration of methane for hydrate formation is clearly revealed. Nucleation of the hydrate can be either impossible or easy and fast depending on the concentration of methane which seems to play the leading role in the understanding of the kinetics of hydrate formation

    Clinical Predictors of Hyperperfusion Syndrome Following Carotid Stenting: Results From a National Prospective Multicenter Study

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    [Objectives] The aim of the HISPANIAS (HyperperfusIon Syndrome Post-carotid ANgIoplasty And Stenting) study was to define CHS rates and develop a clinical predictive model for cerebral hyperperfusion syndrome (CHS) after carotid artery stenting (CAS).[Background] CHS is a severe complication following CAS. The presence of clinical manifestations is estimated on the basis of retrospective reviews and is still uncertain.[Methods] The HISPANIAS study was a national prospective multicenter study with 14 recruiting hospitals. CHS was classified as mild (headache only) and moderate-severe (seizure, impaired level of consciousness, or development of focal neurological signs).[Results] A total of 757 CAS procedures were performed. CHS occurred in 22 (2.9%) patients, in which 16 (2.1%) had moderate-severe CHS and 6 (0.8%) had mild CHS (only headache). The rate of hemorrhages was 0.7% and was associated with high mortality (20%). Pre-operative predictors of moderate-severe CHS in multivariate analysis were female sex (odds ratio [OR]: 3.24; 95% confidence interval [CI]: 1.11 to 9.47; p = 0.03), older patients (OR: 1.09; 95% CI: 1.01 to 1.17; p = 0.02), left carotid artery treated (OR: 4.13; 95% CI: 1.11 to 15.40; p = 0.03), and chronic renal failure (OR: 6.29; 95% CI: 1.75 to 22.57; p = 0.005). The area under the curve of this clinical and radiological model was 0.86 (95% CI: 0.81 to 0.92; p = 0.001).[Conclusions] The rate of CHS in the HISPANIAS study was 2.9%, with moderate-severe CHS of 2.1%. CHS was independently associated with female sex, older age, history of chronic kidney disease, and a treated left carotid artery. Although further investigations are needed, the authors propose a model to identify high-risk patients and develop strategies to decrease CHS morbidity and mortality in the future.This study was supported by a Spanish grant from the Instituto de Salud Carlos III (ISCIII-FIS IP14/00971, 2014–2017). The ITRIBIS project has the registration number REGPOT-2013-1. Cooperative Cerebrovascular Disease Research Network (INVICTUS+) (RD16/0019/0015). Dr. Mancha is supported by a Río Hortega contract (CM16/00015). Abbott and Grifols have partial financial supported the conduction of the HISPANIAS project but had no role in the design of the study, interpretation of the data, or manuscript approval.Peer reviewe
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