Nuevas unidades léxicas en textos académicos y dificultades para su comprensión lectora

The objective of this research was to analyze reading comprehension problems of university students when they find new lexical acquisitions in Spanish texts and the strategies they apply in order to solve comprehension difficulties regarding neologisms. The instrument used to data included a survey applied to five groups of university students from mathematics, engineering, languages, Hispanic letters and pedagogy. Among the most relevant conclusions from the analysis and discussion of the results obtained, we have: difficulties to understand the new terms, lack of a specialized updated dictionary to clear up their doubts, semantic confusion when neologisms are loans from another language, and comprehension problems when neologisms introduced do not follow the linguistic constrains of Spanish word formation. La investigación presentada en este artículo se planteó como objetivo analizar las dificultades de comprensión lectora y las estrategias que aplican para su solución los  estudiantes universitarios cuando encuentran, en sus textos académicos, nuevas adquisiciones lexicales incorporadas al idioma castellano. En base a referencias fue diseñado un instrumento de recolección de datos aplicado a una muestra conformada por cinco grupos de estudiantes, pertenecientes a las áreas de matemática, ingeniería, idiomas, letras hispánicas y pedagogía. Entre las conclusiones más relevantes se encuentran: incomprensión del significado de los términos nuevos debido a su introducción en el lenguaje académico escrito; carencia de diccionarios especializados actualizados que contribuyan a aclarar dudas neológicas; confusión  semántica cuando los neologismos provienen de préstamos de otros idiomas, y problemas de comprensión cuando las nuevas unidades léxicas no cumplen con las restricciones morfofonémicas del castellano para la formación de nuevas palabras

Effect of heuristics on serendipity in path-based storytelling with linked data

Path-based storytelling with Linked Data on the Web provides users the ability to discover concepts in an entertaining and educational way. Given a query context, many state-of-the-art pathfinding approaches aim at telling a story that coincides with the user's expectations by investigating paths over Linked Data on the Web. By taking into account serendipity in storytelling, we aim at improving and tailoring existing approaches towards better fitting user expectations so that users are able to discover interesting knowledge without feeling unsure or even lost in the story facts. To this end, we propose to optimize the link estimation between - and the selection of facts in a story by increasing the consistency and relevancy of links between facts through additional domain delineation and refinement steps. In order to address multiple aspects of serendipity, we propose and investigate combinations of weights and heuristics in paths forming the essential building blocks for each story. Our experimental findings with stories based on DBpedia indicate the improvements when applying the optimized algorithm

Predicting Pregnancy Outcomes Using Longitudinal Information: A Penalized Splines Mixed–Effects Model Approach

We propose a semiparametric mixed–effects model (SNMM) using penalized splines to clas- sify longitudinal data and improve the prediction of a binary outcome. The work is motivated by a study in which different hormone levels were measured during the early stages of preg- nancy, and the challenge is using this information to predict normal versus abnormal pregnancy outcomes. The aim of this paper is to compare models and estimation strategies based on alternative formulations of SNMMs depending on the characteristics of the data set under con- sideration. For our motivating example, we address the classification problem using a particular case of the SNMM in which the parameter space has a finite dimensional component (fixed effects and variance components) and an infinite dimensional component (unknown function) that need to be estimated. The nonparametric component of the model is estimated using pe- nalized splines. For the parametric component, we compare the advantages of using random effects versus direct modeling of the correlation structure of the errors. Numerical studies show that our approach improves over other existing methods for the analysis of this type of data. Furthermore, the results obtained using our method support the idea that explicit modeling of the serial correlation of the error term improves the prediction accuracy with respect to a model with random effects, but independent errors.MTM2014-52184-

A solution for galactic disks with Yukawian gravitational potential

We present a new solution for the rotation curves of galactic disks with gravitational potential of the Yukawa type. We follow the technique employed by Toomre in 1963 in the study of galactic disks in the Newtonian theory. This new solution allows an easy comparison between the Newtonian solution and the Yukawian one. Therefore, constraints on the parameters of theories of gravitation can be imposed, which in the weak field limit reduce to Yukawian potentials. We then apply our formulae to the study of rotation curves for a zero-thickness exponential disk and compare it with the Newtonian case studied by Freeman in 1970. As an application of the mathematical tool developed here, we show that in any theory of gravity with a massive graviton (this means a gravitational potential of the Yukawa type), a strong limit can be imposed on the mass (m_g) of this particle. For example, in order to obtain a galactic disk with a scale length of b ~ 10 kpc, we should have a massive graviton of m_g << 10^{-59} g. This result is much more restrictive than those inferred from solar system observations.Comment: 7 pages; 1 eps figure; to appear in General Relativity and Gravitatio

Potential-density pairs for axisymmetric galaxies: the influence of scalar fields

We present a formulation for potential-density pairs to describe axisymmetric galaxies in the Newtonian limit of scalar-tensor theories of gravity. The scalar field is described by a modified Helmholtz equation with a source that is coupled to the standard Poisson equation of Newtonian gravity. The net gravitational force is given by two contributions: the standard Newtonian potential plus a term stemming from massive scalar fields. General solutions have been found for axisymmetric systems and the multipole expansion of the Yukawa potential is given. In particular, we have computed potential-density pairs of galactic disks for an exponential profile and their rotation curves.Comment: 8 pages, no figures, corrected version to the one that will appear in Gen. Relativ. Gravit., where a small typo in eq. (13) is presen

Aplicação do método de análise hierárquica na seleção de revestimentos anticorrosivos para equipamentos contidos em paradas de produção de plataformas marítimas

Neste artigo é proposto um modelo de auxílio multicritério para orientação da escolha do revestimento anticorrosivo nos equipamentos de processo contidos nas plataformas marítimas nos períodos de paradas de produção. Foi utilizado o método de Análise Hierárquica (AHP), que é amplamente utilizado e serve como base de referência no processo de tomada de decisão com vários critérios. Uma estrutura hierárquica foi também proposta após a identificação dos critérios (tempo, custo e qualidade), dos subcritérios (o tempo de aplicação e o tempo de cura do mesmo) e das alternativas viáveis. Questionários foram aplicados a um grupo de especialistas selecionados a fim de determinar a prioridade dos critérios e subcritérios. As prioridades das alternativas foram feitas baseadas em escalas de comparação propostas neste trabalho. Para aplicação do método foram utilizados dados de vinte equipamentos de processos contidos em paradas de produção de plataformas marítimas localizados na Bacia de Campos, litoral do estado de Rio de Janeiro. Os resultados apresentados foram satisfatórios e evidenciaram a viabilidade da utilização do método AHP para seleção dos revestimentos anticorrosivos para os equipamentos de processos.Sociedad Argentina de Informática e Investigación Operativa (SADIO

Aplicação do método de análise hierárquica na seleção de revestimentos anticorrosivos para equipamentos contidos em paradas de produção de plataformas marítimas

Neste artigo é proposto um modelo de auxílio multicritério para orientação da escolha do revestimento anticorrosivo nos equipamentos de processo contidos nas plataformas marítimas nos períodos de paradas de produção. Foi utilizado o método de Análise Hierárquica (AHP), que é amplamente utilizado e serve como base de referência no processo de tomada de decisão com vários critérios. Uma estrutura hierárquica foi também proposta após a identificação dos critérios (tempo, custo e qualidade), dos subcritérios (o tempo de aplicação e o tempo de cura do mesmo) e das alternativas viáveis. Questionários foram aplicados a um grupo de especialistas selecionados a fim de determinar a prioridade dos critérios e subcritérios. As prioridades das alternativas foram feitas baseadas em escalas de comparação propostas neste trabalho. Para aplicação do método foram utilizados dados de vinte equipamentos de processos contidos em paradas de produção de plataformas marítimas localizados na Bacia de Campos, litoral do estado de Rio de Janeiro. Os resultados apresentados foram satisfatórios e evidenciaram a viabilidade da utilização do método AHP para seleção dos revestimentos anticorrosivos para os equipamentos de processos.Sociedad Argentina de Informática e Investigación Operativa (SADIO

Stellar population gradients from cosmological simulations: dependence on mass and environment in local galaxies

The age and metallicity gradients for a sample of group and cluster galaxies from N-body+hydrodynamical simulation are analyzed in terms of galaxy stellar mass. Dwarf galaxies show null age gradient with a tail of high and positive values for systems in groups and cluster outskirts. Massive systems have generally zero age gradients which turn to positive for the most massive ones. Metallicity gradients are distributed around zero in dwarf galaxies and become more negative with mass; massive galaxies have steeper negative metallicity gradients, but the trend flatten with mass. In particular, fossil groups are characterized by a tighter distribution of both age and metallicity gradients. We find a good agreement with both local observations and independent simulations. The results are also discussed in terms of the central age and metallicity, as well as the total colour, specific star formation and velocity dispersion.Comment: 9 pages, 5 figures, accepted for publication on MNRA