1,177 research outputs found

    Evaluación nutricional de escolares Hausa de Batata (Sur de Níger)

    Get PDF
    The present paper studies the nutritional status assessment of Niger rural schoolchildren using body composition anthropometric estimators. Likewise, validity of exclusive use of traditional indicators –weight, height and Body Mass Index (BMI)- is evaluated. The sample is composed of 137 Hausa schoolchildren, between 6 and 15 years old from Sae Saboua comunity, Batata. Twelve anthropometric direct measurements were taken. BMI was calculated, mid-arm and total body composition were estimated. NHANES I y II for black population was selected as reference criteria (Frisancho 1990). Results show that BMI tends to underestimate protein malnutrition and overrate caloric one in a way that body composition analysis is necessary for a correct nutritional status assessment.En el presente trabajo se evalúa la condición nutricional de una población escolar del medio rural del Sur de Niger a través de estimadores antropométricos de composición corporal. Al mismo tiempo, se analiza la validez del uso exclusivo de los indicadores habitualmente utilizados de peso, talla, Indice Córmico (IC) e Índice de Masa Corporal (IMC). La muestra se compone de 137 niños y niñas de etnia Hausa, entre 6 y 15 años de edad de la comunidad de Sae Saboua, Batata. Mediante la técnica antropométrica, se tomaron 12 medidas directas a partir de las cuales se calculó el IMC y se estimó la composición corporal mesobraquial y total. Como referencia se consideró el estándar NHANES I y II para población negra (Frisancho 1990). Se deduce de los resultados que el IMC y el peso/talla tienden a subestimar la desnutrición proteica y sobrestimar la desnutrición calórica, de manera que para un correcto diagnóstico del estado nutricional es imprescindible el análisis de la composición corporal

    Dynamic performance of existing double track railway bridges at resonance with the increase of the operational line speed

    Get PDF
    [EN] This article addresses the dynamic behaviour of double track simply supported bridges of short to medium span lengths (10 m < L< 25 m) belonging to conventional railway lines. These structures are susceptible to experience inadmissible levels of vertical vibrations when traversed by trains at high speeds, and in certain cases their dynamic performance may require to be re-evaluated in case of an increase of the traffic velocity above 200 km/h. In engineering consultancies, these structures have been traditionally analysed under the passage of trains at different speeds using planar models, neglecting the contribution of transverse vibration modes and also the flexibility of the elastomeric bearings. The study presented herein endeavours to evaluate the influence of these two aspects in the verification of the Serviceability Limit State of vertical accelerations, which is of great interest in order to guarantee a conservative prediction of the dynamic behaviour. In the present study, the dynamic response of representative slab and girder bridges has been evaluated using an orthotropic plate finite element model, leading to practical conclusions regarding the circumstances under which the above mentioned factors should be considered in order to adequately evaluate the transverse vibration levels of the deck.Moliner, E.; Martínez-Rodrigo, M.; Museros Romero, P. (2017). Dynamic performance of existing double track railway bridges at resonance with the increase of the operational line speed. Engineering Structures. 132:98-109. doi:10.1016/j.engstruct.2016.11.031S9810913

    Polymer-solvent interaction parameters of SBS rubbers by inverse gas chromatography measurements

    Get PDF
    The solubility parameters of two SBS commercial rubbers with different structures (lineal and radial), and with slightly different styrene content have been determined by inverse gas chromatography technique. The Flory–Huggins interaction parameters of several polymer–solvent mixtures have also been calculated. The influence of the polymer composition, the solvent molecular weight and the temperature over these parameters have been discussed; besides, these parameters have been compared with previous ones, obtained by intrinsic viscosity measurements. From the Flory–Huggins interaction parameters, the infinite dilution activity coefficients of the solvents have been calculated and fitted to the well-known NRTL model. These NRTL binary interaction parameters have a great importance in modelling the separation steps in the process of obtaining the rubber

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

    Get PDF
    [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

    Peroxidase expression in a cereal cyst nematode (Heterodera avenae) resistant hexaploid wheat line.

    Full text link
    The incompatible interaction between plant and pathogen is often determined by the hypersensitive reaction (HR). This response is associated with accumulation of reactive oxygen species (ROS), which results in adverse growth conditions for pathogens. Two major mechanisms involving either NADPH oxidases or peroxidases have been proposed for generation of ROS. Peroxidases (PER, EC 1.11.1.7), present in all land plants, are members of a large multigenic family with high number of isoforms involved in a broad range of physiological processes. PER genes, which are expressed in nematode feeding sites, have been identified in several plant species (Zacheo et al. 1997). A strong correlation between HR and PER activities at four and seven days post nematode infection, was detected in roots of wheat lines carrying Cre2, Cre5 (from Ae. ventricosa) or Cre7 (from Ae. triuncialis) Heterodera avenae resistance genes (Andrés et al. 2001; Montes et al. 2003, 2004). We have studied changes in root of peroxidase mRNAs levels after infection by H. avenae of a wheat/Ae. ven¬tricosa introgression line (H-93-8) carrying Cre2 (Delibes et al. 1993). We also report and classify the predicted protein sequences derived from complete peroxidase transcripts

    Altered development of white matter in youth at high familial risk for bipolar disorder: a diffusion tensor imaging study

    Get PDF
    Objective: To study white matter (WM) development in youth at high familial risk for bipolar disorder (BD). WM alterations are reported in youth and adults with BD. WM undergoes important maturational changes in adolescence. Age-related changes in WM microstructure using diffusion tensor imaging with tract-based spatial statistics in healthy offspring having a parent with BD were compared with those in healthy controls. Method: A total of 45 offspring participated, including 20 healthy offspring with a parent diagnosed with BD (HBO) and 25 healthy control offspring of healthy parents (CONT). All were free of medical and psychiatric disorders. Mean fractional anisotropy (FA), radial diffusivity (RD), and longitudinal diffusivity were examined using whole-brain analyses, co-varying for age. Results: Group-by-age interactions showed a linear increase in FA and a linear decrease in RD in CONT in the left corpus callosum and right inferior longitudinal fasciculus. In HBO, there was a linear decrease in FA and an increase in RD with age in the left corpus callosum and no relation between FA or RD and age in the right inferior longitudinal fasciculus. Curve fitting confirmed linear and showed nonlinear relations between FA and RD and age in these regions in CONT and HBO. Conclusions: This is the first study to examine WM in healthy offspring at high familial risk for BD. Results from this cross-sectional study suggest altered development of WM in HBO compared with CONT in the corpus callosum and temporal associative tracts, which may represent vulnerability markers for future BD and other psychiatric disorders in HBO. J. Am. Acad. Child Adolesc. Psychiatry, J. Am. Acad. Child Adolesc. Psychiatry, 2010; 49(12):1249 -1259. Key words: bipolar disorder, familial risk, white matter, diffusion tensor imaging, neurodevelopment B ipolar disorder (BD) is a serious psychiatric illness affecting 1% to 3% of the adult population and remains a leading cause of morbidity, functional impairment, and completed suicide. 1 BD is characterized by difficulties in the regulation of emotions and behavior, as indicated by episodes of mania and depression. BD is highly heritable: the risk of BD is much greater in first-degree relatives of individuals diagnosed with BD. 2,3 Recent evidence has indicated that offspring of parents with BD are at increased risk for BD and other psychiatric disorders, including BD spectrum disorder, anxiety, and depression disorders. 2 Although genetic and environmental factors and their interactions are important in the development of BD, abnormalities of brain structure and function that most likely mediate these effects have yet to be elucidated. Converging evidence from epidemiologic, genetic, and neuroimaging studies has suggested that abnormalities in the development of white matter (WM) may play an important role in the neuropathophysiology of BD

    Regulation and role of the PP2A-B56 holoenzyme family in cancer

    Get PDF
    Protein phosphatase 2A (PP2A) inactivation is common in cancer, leading to sustained activation of pro-survival and growth-promoting pathways. PP2A consists of a scaffolding A-subunit, a catalytic C-subunit, and a regulatory B-subunit. The functional complexity of PP2A holoenzymes arises mainly through the vast repertoire of regulatory B-subunits, which determine both their substrate specificity and their subcellular localization. Therefore, a major challenge for developing more effective therapeutic strategies for cancer is to identify the specific PP2A complexes to be targeted. Of note, the development of small molecules specifically directed at PP2A-B56α has opened new therapeutic avenues in both solid and hematological tumors. Here, we focus on the B56/PR61 family of PP2A regulatory subunits, which have a central role in directing PP2A tumor suppressor activity. We provide an overview of the mechanisms controlling the formation and regulation of these complexes, the pathways they control, and the mechanisms underlying their deregulation in cancer

    Approximating the solution stochastic process of the random Cauchy one-dimensional heat model

    Get PDF
    [EN] This paper deals with the numerical solution of the random Cauchy one-dimensional heat model. We propose a random finite difference numerical scheme to construct numerical approximations to the solution stochastic process. We establish sufficient conditions in order to guarantee the consistency and stability of the proposed random numerical scheme.The theoretical results are illustrated by means of an example where reliable approximations of the mean and standard deviation to the solution stochastic process are given.This work has been partially supported by the Ministerio de Economía y Competitividad Grant MTM2013-41765-P. Ana Navarro Quiles acknowledges the doctorate scholarship granted by Programa de Ayudas de Investigación y Desarrollo (PAID), Universitat Politècnica de València. M. A. Sohaly is also indebted to Egypt Ministry of Higher Education, Cultural Affairs, for its financial support [mohe-casem (2016)].Navarro Quiles, A.; Romero, J.; Roselló, M.; Sohaly, M. (2016). Approximating the solution stochastic process of the random Cauchy one-dimensional heat model. Abstract and Applied Analysis. 2016:1-7. https://doi.org/10.1155/2016/5391368S172016Logan, J. D. (2004). Partial Differential Equations on Bounded Domains. Undergraduate Texts in Mathematics, 121-171. doi:10.1007/978-1-4419-8879-9_4Wang, J. (1994). A Model of Competitive Stock Trading Volume. Journal of Political Economy, 102(1), 127-168. doi:10.1086/261924Tsynkov, S. V. (1998). Numerical solution of problems on unbounded domains. A review. Applied Numerical Mathematics, 27(4), 465-532. doi:10.1016/s0168-9274(98)00025-7Koleva, M. N. (2006). Numerical Solution of the Heat Equation in Unbounded Domains Using Quasi-uniform Grids. Lecture Notes in Computer Science, 509-517. doi:10.1007/11666806_58Han, H., & Huang, Z. (2002). A class of artificial boundary conditions for heat equation in unbounded domains. Computers & Mathematics with Applications, 43(6-7), 889-900. doi:10.1016/s0898-1221(01)00329-7Wu, X., & Sun, Z.-Z. (2004). Convergence of difference scheme for heat equation in unbounded domains using artificial boundary conditions. Applied Numerical Mathematics, 50(2), 261-277. doi:10.1016/j.apnum.2004.01.001Cortés, J. C., Sevilla-Peris, P., & Jódar, L. (2005). Analytic-numerical approximating processes of diffusion equation with data uncertainty. Computers & Mathematics with Applications, 49(7-8), 1255-1266. doi:10.1016/j.camwa.2004.05.015Casabán, M.-C., Cortés, J.-C., García-Mora, B., & Jódar, L. (2013). Analytic-Numerical Solution of Random Boundary Value Heat Problems in a Semi-Infinite Bar. Abstract and Applied Analysis, 2013, 1-9. doi:10.1155/2013/676372Casabán, M.-C., Company, R., Cortés, J.-C., & Jódar, L. (2014). Solving the random diffusion model in an infinite medium: A mean square approach. Applied Mathematical Modelling, 38(24), 5922-5933. doi:10.1016/j.apm.2014.04.063Villafuerte, L., Braumann, C. A., Cortés, J.-C., & Jódar, L. (2010). Random differential operational calculus: Theory and applications. Computers & Mathematics with Applications, 59(1), 115-125. doi:10.1016/j.camwa.2009.08.061Øksendal, B. (2003). Stochastic Differential Equations. Universitext. doi:10.1007/978-3-642-14394-6Kloeden, P. E., & Platen, E. (1992). Numerical Solution of Stochastic Differential Equations. doi:10.1007/978-3-662-12616-5Holden, H., Øksendal, B., Ubøe, J., & Zhang, T. (2010). Stochastic Partial Differential Equations. doi:10.1007/978-0-387-89488-
    corecore