Influence of track modelling in modal parameters of railway bridges composed by single-track adjacent decks

[EN] A significant number of railway bridges composed by simply-supported (SS) spans are present in existing railway lines. Special attention must be paid to short to medium span length structures, as they are prone to experience high vertical acceleration levels at the deck, due to their low weight and damping, compromising the travelling comfort and the structural integrity. The accurate prediction of the dynamic response of these bridges is a complex issue since it is affected by uncertain factors such as structural damping and complex interaction mechanisms such as vehicle-bridge, soil-structure or track-bridge interaction. Concerning track-bridge interaction, experimental evidences of a dynamic coupling exerted by the ballasted track between subsequent SS spans and also between structurally independent single-track twin adjacent decks have been reported in the literature [1, 2]. Nevertheless, this phenomenon is frequently disregarded due to the computational cost of models including the track and due to the uncertainties in the mechanical parameters that define the track system. The present work contributes to the study of the coupling effect exerted by the ballasted track between independent structures in railway bridges. With this purpose two 3D finite element (FE) track-bridge interaction models are implemented. The former includes a continuous representation of the track components meshing the sleepers, ballast and sub-ballast with solid FE. In the latter, the track is represented as a 2D discrete three-layer model where the mass, stiffness and damping of the components are concentrated at the sleepers locations. The numerical models are updated with experimental measurements performed on an existing railway bridge in a view to evaluate (i) the influence of the track continuity on the bridge modal parameters and on the train-induced vibrations; (ii) the adequacy of the implemented numerical models and (iii) the importance of the track-bridge interaction for an accurate prediction of the vertical acceleration levels under operating conditions.The authors would like to acknowledge the financial support provided by the Spanish Ministry of Science and Innovation under research project PID2019-109622RB; FEDER Andalucía 2014-2020 Operational Program for project US-126491; Generalitat Valenciana and Universitat Jaume I under research projects AICO2019/175 and UJI/A2008/06; and the Andalusian Scientific Computing Centre (CICA).Sánchez Quesada, J.; Moliner, E.; Romero, A.; Galvín, P.; Martínez-Rodrigo, M. (2022). Influence of track modelling in modal parameters of railway bridges composed by single-track adjacent decks. En Proceedings of the YIC 2021 - VI ECCOMAS Young Investigators Conference. Editorial Universitat Politècnica de València. 278-287. https://doi.org/10.4995/YIC2021.2021.12283OCS27828

Nonlinear Integer Programming

Research efforts of the past fifty years have led to a development of linear integer programming as a mature discipline of mathematical optimization. Such a level of maturity has not been reached when one considers nonlinear systems subject to integrality requirements for the variables. This chapter is dedicated to this topic. The primary goal is a study of a simple version of general nonlinear integer problems, where all constraints are still linear. Our focus is on the computational complexity of the problem, which varies significantly with the type of nonlinear objective function in combination with the underlying combinatorial structure. Numerous boundary cases of complexity emerge, which sometimes surprisingly lead even to polynomial time algorithms. We also cover recent successful approaches for more general classes of problems. Though no positive theoretical efficiency results are available, nor are they likely to ever be available, these seem to be the currently most successful and interesting approaches for solving practical problems. It is our belief that the study of algorithms motivated by theoretical considerations and those motivated by our desire to solve practical instances should and do inform one another. So it is with this viewpoint that we present the subject, and it is in this direction that we hope to spark further research.Comment: 57 pages. To appear in: M. J\"unger, T. Liebling, D. Naddef, G. Nemhauser, W. Pulleyblank, G. Reinelt, G. Rinaldi, and L. Wolsey (eds.), 50 Years of Integer Programming 1958--2008: The Early Years and State-of-the-Art Surveys, Springer-Verlag, 2009, ISBN 354068274

Long-term antibiotic therapy in patients with surgery-indicated not undergoing surgery infective endocarditis

Background: To date, there is little information regarding management of patients with infective endocarditis (IE) that did not undergo an indicated surgery. Therefore, we aimed to evaluate prognosis of these patients treated with a long-term antibiotic treatment strategy, including oral long term suppressive antibiotic treatment in five referral centres with a multidisciplinary endocarditis team. Methods: This retrospective, multicenter study retrieved individual patient-level data from five referral centres in Spain. Among a total of 1797, 32 consecutive patients with IE were examined (median age 72 years; 78% males) who had not undergone an indicated surgery, but received long-term antibiotic treatment (LTAT) and were followed by a multidisciplinary endocarditis team, between 2011 and 2019. Primary outcomes were infection relapse and mortality during follow-up. Results: Among 32 patients, 21 had IE associated with prostheses. Of the latter, 8 had an ascending aorta prosthetic graft. In 24 patients, a switch to long-term oral suppressive antibiotic treatment (LOSAT) was considered. The median duration of LOSAT was 277 days. Four patients experienced a relapse during follow-up. One patient died within 60 days, and 12 patients died between 60 days and 3 years. However, only 4 deaths were related to IE. Conclusions: The present study results suggest that a LTAT strategy, including LOSAT, might be considered for patients with IE that cannot undergo an indicated surgery. After hospitalization, they should be followed by a multidisciplinary endocarditis team

Adsorption of mono- and multivalent cat- and anions on DNA molecules

Adsorption of monovalent and multivalent cat- and anions on a deoxyribose nucleic acid (DNA) molecule from a salt solution is investigated by computer simulation. The ions are modelled as charged hard spheres, the DNA molecule as a point charge pattern following the double-helical phosphate strands. The geometrical shape of the DNA molecules is modelled on different levels ranging from a simple cylindrical shape to structured models which include the major and minor grooves between the phosphate strands. The densities of the ions adsorbed on the phosphate strands, in the major and in the minor grooves are calculated. First, we find that the adsorption pattern on the DNA surface depends strongly on its geometrical shape: counterions adsorb preferentially along the phosphate strands for a cylindrical model shape, but in the minor groove for a geometrically structured model. Second, we find that an addition of monovalent salt ions results in an increase of the charge density in the minor groove while the total charge density of ions adsorbed in the major groove stays unchanged. The adsorbed ion densities are highly structured along the minor groove while they are almost smeared along the major groove. Furthermore, for a fixed amount of added salt, the major groove cationic charge is independent on the counterion valency. For increasing salt concentration the major groove is neutralized while the total charge adsorbed in the minor groove is constant. DNA overcharging is detected for multivalent salt. Simulations for a larger ion radii, which mimic the effect of the ion hydration, indicate an increased adsorbtion of cations in the major groove.Comment: 34 pages with 14 figure

Relationship between olive oil consumption and ankle-brachial pressure index in a population at high cardiovascular risk

The aim of this study was to ascertain the association between the consumption of different categories of edible olive oils (virgin olive oils and olive oil) and olive pomace oil and ankle-brachial pressure index (ABI) in participants in the PREDIMED-Plus study, a trial of lifestyle modification for weight and cardiovascular event reduction in individuals with overweight/obesity harboring the metabolic syndrome. Methods: We performed a cross-sectional analysis of the PREDIMED-Plus trial. Consumption of any category of olive oil and olive pomace oil was assessed through a validated food-frequency questionnaire. Multivariable linear regression models were fitted to assess associations between olive oil consumption and ABI. Additionally, ABI ≤1 was considered as the outcome in logistic models with different categories of olive oil and olive pomace oil as exposure. Results: Among 4330 participants, the highest quintile of total olive oil consumption (sum of all categories of olive oil and olive pomace oil) was associated with higher mean values of ABI (beta coefficient: 0.014, 95% confidence interval [CI]: 0.002, 0.027) (p for trend = 0.010). Logistic models comparing the consumption of different categories of olive oils, olive pomace oil and ABI ≤1 values revealed an inverse association between virgin olive oils consumption and the likelihood of a low ABI (odds ratio [OR] 0.73, 95% CI [0.56, 0.97]), while consumption of olive pomace oil was positively associated with a low ABI (OR 1.22 95% CI [1.00, 1.48]). Conclusions: In a Mediterranean population at high cardiovascular risk, total olive oil consumption was associated with a higher mean ABI. These results suggest that olive oil consumption may be beneficial for peripheral artery disease prevention, but longitudinal studies are needed

Personal adjustment in children and adolescents diabetics and non-diabetics

La siguiente investigación pretende comprobar la existencia de posibles diferencias entre un grupo de niños y adolescentes diabéticos con otro que no lo es, en lo que a ajuste personal se refiere. En el estudio participaron un total de 88 familias con hijos de entre 10 y 18 años, de los cuales 42 niños padecían diabetes y los otros 46 no. El instrumento seleccionado para medir el ajuste social (compuesto por las dimensiones de autoestima, confianza en sí mismo, relaciones interpersonales y relaciones con los padres) ha sido el Sistema de Evaluación de la Conducta de Niños y Adolescentes (BASC). Los análisis de diferencia de muestras concluyen que los niños diabéticos tienden a puntuar más bajo en dicha dimensión global, si bien las diferencias halladas entre ambos grupos no son significativas. Sin embargo, en las subescalas de confianza en sí mismos (niños) y autoestima (adolescentes) sí se pueden observar diferencias significativas entre ambos grupos. Dichas puntuaciones sugieren que, como vienen mostrando numerosos estudios en este ámbito, la aparición de esta enfermedad produce altos índices de depresión, ansiedad y baja autoestima –principalmente durante la adolescencia–, por lo que se han de promover actitudes positivas y de resiliencia que mejoren dicha situación. Asimismo, demuestran la importancia de enfatizar la independencia de niños con diabetes, para ayudarlos a ganar confianza en sí mismos en pro de mejorar esta habilidad.The following research aims to check for possible differences between a group of children and adolescents with diabetes and a group with no diabetes, in regards to personal adjustment. A total of 88 families with children between the ages of 10 and 18 years old participated in the study, of which 42 suffer from diabetes and the other 46 do not suffer from diabetes. The instrument selected for measuring social adjustment (dimensions made up of self-esteem, self- confidence, interpersonal relationships and relationships with parents) was the Behavior Assessment System for Children (BASC). The different sample analyses conclude that diabetic children tend to score lower in this global dimension, although the differences found between both groups are not significant. However, the subscales of self- confidence (children) and self-esteem (adolescents) are able to observe significant differences between both groups. These scores suggest that, as numerous studies from this field have been showing, the appearance of this illness causes high rates of depression, anxiety, and low self-esteem mainly during adolescence, that’s why they have to promote positive attitudes and resilience in order to improve their situation. They also demonstrate the importance of emphasizing the independence of children with diabetes, in order to help them gain self- confidence in support of improving this skill

Personal adjustment in children and adolescents diabetics and non-diabetics

La siguiente investigación pretende comprobar la existencia de posibles diferencias entre un grupo de niños y adolescentes diabéticos con otro que no lo es, en lo que a ajuste personal se refiere. En el estudio participaron un total de 88 familias con hijos de entre 10 y 18 años, de los cuales 42 niños padecían diabetes y los otros 46 no. El instrumento seleccionado para medir el ajuste social (compuesto por las dimensiones de autoestima, confianza en sí mismo, relaciones interpersonales y relaciones con los padres) ha sido el Sistema de Evaluación de la Conducta de Niños y Adolescentes (BASC). Los análisis de diferencia de muestras concluyen que los niños diabéticos tienden a puntuar más bajo en dicha dimensión global, si bien las diferencias halladas entre ambos grupos no son significativas. Sin embargo, en las subescalas de confianza en sí mismos (niños) y autoestima (adolescentes) sí se pueden observar diferencias significativas entre ambos grupos. Dichas puntuaciones sugieren que, como vienen mostrando numerosos estudios en este ámbito, la aparición de esta enfermedad produce altos índices de depresión, ansiedad y baja autoestima –principalmente durante la adolescencia–, por lo que se han de promover actitudes positivas y de resiliencia que mejoren dicha situación. Asimismo, demuestran la importancia de enfatizar la independencia de niños con diabetes, para ayudarlos a ganar confianza en sí mismos en pro de mejorar esta habilidad.The following research aims to check for possible differences between a group of children and adolescents with diabetes and a group with no diabetes, in regards to personal adjustment. A total of 88 families with children between the ages of 10 and 18 years old participated in the study, of which 42 suffer from diabetes and the other 46 do not suffer from diabetes. The instrument selected for measuring social adjustment (dimensions made up of self-esteem, self- confidence, interpersonal relationships and relationships with parents) was the Behavior Assessment System for Children (BASC). The different sample analyses conclude that diabetic children tend to score lower in this global dimension, although the differences found between both groups are not significant. However, the subscales of self- confidence (children) and self-esteem (adolescents) are able to observe significant differences between both groups. These scores suggest that, as numerous studies from this field have been showing, the appearance of this illness causes high rates of depression, anxiety, and low self-esteem mainly during adolescence, that’s why they have to promote positive attitudes and resilience in order to improve their situation. They also demonstrate the importance of emphasizing the independence of children with diabetes, in order to help them gain self- confidence in support of improving this skill

Gender differences in executive functions in Preschool children aged five years

Estudios previos en niños en edad preescolar han proporcionado evidencias de que las niñas presentan mayores niveles de funciones ejecutivas que los niños. Las chicas suelen superar a los chicos en algunas tareas ejecutivas, especialmente en aquellas que requieren de control inhibitorio, control emocional y aquellas que implican un retraso de la gratificación. Por el contrario, otros estudios no han logrado encontrar diferencias de género en las tareas que requieren del funcionamiento ejecutivo. Dado que en la actualidad, existe mucha controversia sobre la influencia del género en las funciones ejecutivas, la presente investigación pretende estudiar si los niños y las niñas difieren en la puntuación obtenida en funciones ejecutivas. Se espera que las niñas obtengan puntuaciones significativamente superiores que los niños. En el estudio participaron 66 alumnos/as (37 niños y 29 niñas) de 5 años de edad, matriculados en el tercer curso de Educación Infantil, en un centro concertado de la provincia de Granada. Los resultados indican que los sujetos presentan niveles dispares en las variables inhibición, memoria, flexibilidad y planificación. No se encontraron diferencias significativas en el resto de variables analizadas: control emocional y total de funciones ejecutivas. En conclusión, las diferencias de género en las funciones ejecutivas sigue siendo un ámbito controvertido con resultados muy dispares. Por tanto, sería interesante realizar estudios longitudinales que permitan conocer si existen diferencias de género en las funciones ejecutivas, y si las diferencias permanecen a lo largo del tiempo.Prior researches in preschool have proved that girls have higher levels of executive functions than boys. Girls use to lead boys in some executive tasks, especially in those that demand inhibitory and emotional control, and those that involve delayed gratification. On the other side, other studies do not find any gender differences in tasks related to executive functions. Nowadays there is a lot of controversy about the influence of gender in executive functions; so that research aims to study whether there is any difference between boys and girls in executive functions. It is expected that girls obtain significantly higher scores than boys. The study involved 66 students (37 boys and 29 girls) from 5 years old, enrolled in the last year of kindergarten, in a private publicly funded school in Granada. Results indicate that subjects present different levels in the variables of memory, inhibition, flexibility and planning. No significant differences in the other variables analysed were found: emotional control and total control of executive functions. In conclusion, gender differences in executive functions remain a controversial area with very different results. Therefore, it would be interesting to conduct longitudinal studies to know if there are gender differences in executive functions, and if these differences remain over time.Investigación realizada gracias a la ayuda para la formación de profesorado universitario (FPU) del Ministerio de Educación, Cultura y Deporte

Gender differences in executive functions in Preschool children aged five years

Estudios previos en niños en edad preescolar han proporcionado evidencias de que las niñas presentan mayores niveles de funciones ejecutivas que los niños. Las chicas suelen superar a los chicos en algunas tareas ejecutivas, especialmente en aquellas que requieren de control inhibitorio, control emocional y aquellas que implican un retraso de la gratificación. Por el contrario, otros estudios no han logrado encontrar diferencias de género en las tareas que requieren del funcionamiento ejecutivo. Dado que en la actualidad, existe mucha controversia sobre la influencia del género en las funciones ejecutivas, la presente investigación pretende estudiar si los niños y las niñas difieren en la puntuación obtenida en funciones ejecutivas. Se espera que las niñas obtengan puntuaciones significativamente superiores que los niños. En el estudio participaron 66 alumnos/as (37 niños y 29 niñas) de 5 años de edad, matriculados en el tercer curso de Educación Infantil, en un centro concertado de la provincia de Granada. Los resultados indican que los sujetos presentan niveles dispares en las variables inhibición, memoria, flexibilidad y planificación. No se encontraron diferencias significativas en el resto de variables analizadas: control emocional y total de funciones ejecutivas. En conclusión, las diferencias de género en las funciones ejecutivas sigue siendo un ámbito controvertido con resultados muy dispares. Por tanto, sería interesante realizar estudios longitudinales que permitan conocer si existen diferencias de género en las funciones ejecutivas, y si las diferencias permanecen a lo largo del tiempo.Prior researches in preschool have proved that girls have higher levels of executive functions than boys. Girls use to lead boys in some executive tasks, especially in those that demand inhibitory and emotional control, and those that involve delayed gratification. On the other side, other studies do not find any gender differences in tasks related to executive functions. Nowadays there is a lot of controversy about the influence of gender in executive functions; so that research aims to study whether there is any difference between boys and girls in executive functions. It is expected that girls obtain significantly higher scores than boys. The study involved 66 students (37 boys and 29 girls) from 5 years old, enrolled in the last year of kindergarten, in a private publicly funded school in Granada. Results indicate that subjects present different levels in the variables of memory, inhibition, flexibility and planning. No significant differences in the other variables analysed were found: emotional control and total control of executive functions. In conclusion, gender differences in executive functions remain a controversial area with very different results. Therefore, it would be interesting to conduct longitudinal studies to know if there are gender differences in executive functions, and if these differences remain over time.Investigación realizada gracias a la ayuda para la formación de profesorado universitario (FPU) del Ministerio de Educación, Cultura y Deporte