A KD-trees based method for fast radiation source representation for virtual reality dosimetry applications in nuclear safeguards and security

[EN] With the aim of demonstrating the concrete advantages that novel technologies such as Virtual (VR) can provide to the nuclear industry, the authors of this paper have been working on the development of a VR based simulator of a gamma dose rate detector for training purposes, to be applied in the field of nuclear security and safety. Historically in nuclear science, simulating gamma dose rate transport has had a series of requirements, most importantly the accuracy of the computation. When embedding this dose rate computation in the environment of a VR based application, a second and opposing key requirement appears: real time performance. Meeting this requirement is only possible if a fast method to compute gamma radiation is used. In order to achieve this target the authors have been working in ways of improving the efficiency of the Point-Kernel method by reducing its computational effort. This paper presents the latest step in this pursuit of efficiency; a novel method based on a non-regular kernel approach, combined with a KD-tree based volume division method. Devised to reduce as much as possible the number of points that represent the volume of the source while aiming at retaining sufficient dose computation accuracy. (C) 2016 Elsevier Ltd. All rights reserved.This project is fully funded by the Institute of Transuranium Elements of the European Commission's Joint Research Centre, Ispra site, Italy.Moltó-Caracena, T.; Vendrell Vidal, E.; Goncalves, JG.; Peerani, P. (2017). A KD-trees based method for fast radiation source representation for virtual reality dosimetry applications in nuclear safeguards and security. Progress in Nuclear Energy. 95:78-83. https://doi.org/10.1016/j.pnucene.2016.12.001S78839

A variable point kernel dosimetry method for virtual reality simulation applications in nuclear safeguards and security

© 2013 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.This paper presents an algorithm to calculate gamma dose rates intended for virtual reality (VR) applications. It dynamically adapts the method to cope with both accuracy and time requirements. Given the real-time constraints imposed by VR applications, more accurate, but computationally intensive stochastic algorithms (e.g., Monte Carlo) are not suited to this task. On the opposite end, a Point Kernel (PK) method can be effective in some cases with as little as one point (mono PK) to define a source, in contrast with the millions of points that Monte Carlo computes. Simple mono PK codes may lack the desired accuracy in some circumstances, requiring a more detailed source representation. In this work, a novel method is presented which automatically estimates the appropriate level of detail for a source's volumetric representation, then generates a non-regular mesh model and subsequently computes the dose rate via a PK method, performing this three-step process in real time.This work was supported by the European Commission's Joint Research Centre Ph.D. grant program.Moltó Caracena, T.; Gonçalves, JGM.; Peerani, P.; Vendrell Vidal, E. (2013). A variable point kernel dosimetry method for virtual reality simulation applications in nuclear safeguards and security. IEEE Transactions on Nuclear Science. 60(5):3862-3871. doi:10.1109/TNS.2013.2279411S3862387160

Tissue-specific effects of central leptin on the expression of genes involved in lipid metabolism in liver and white adipose tissue

Copyright (2007) The Endocrine Society .The paper can be found at the following URL on the website http://endo.endojournals.org

Ageing alters the lipid sensing process in the hypothalamus of Wistar rats. Effect of food restriction

Lipids regulate a wide range of biological processes. The mechanisms by which fatty acids (FA) and its metabolites influence the hypothalamic regulation of energy homeostasis have been highly studied. However, the effect of ageing and food restriction (FR) on this process is unknown. Herein, we analyzed the gene expression, protein and phosphorylation levels of hypothalamic enzymes and transcription factors related to lipid metabolism. Experiments were performed in male Wistar rats of 3-, 8- and 24-month-old Wistar rats fed ad libitum (AL), as ageing model. Besides, 5- and 21-month-old rats were subjected to a moderate FR protocol (equivalent to ≈ 80% of normal food intake) for three months before the sacrifice. Aged Wistar rats showed a situation of chronic lipid excess as a result of an increase in de novo FA synthesis and FA levels that reach the brain, contributing likely to the development of central leptin and insulin resistance. We observe a hypothalamic downregulation of AMP-activated protein kinase (AMPK) and stearoyl-CoA desaturase (SCD1) and an increase of carnitine palmitoyltransferase-1c (CPT1c) expression

Polygenic contribution to the relationship of loneliness and social isolation with schizophrenia

Previous research suggests an association of loneliness and social isolation (LNL-ISO) with schizophrenia. Here, we demonstrate a LNL-ISO polygenic score contribution to schizophrenia risk in an independent case-control sample (N = 3,488). We then subset schizophrenia predisposing variation based on its effect on LNL-ISO. We find that genetic variation with concordant effects in both phenotypes shows significant SNP-based heritability enrichment, higher polygenic contribution in females, and positive covariance with mental disorders such as depression, anxiety, attention-deficit hyperactivity disorder, alcohol dependence, and autism. Conversely, genetic variation with discordant effects only contributes to schizophrenia risk in males and is negatively correlated with those disorders. Mendelian randomization analyses demonstrate a plausible bi-directional causal relationship between LNL-ISO and schizophrenia, with a greater effect of LNL-ISO liability on schizophrenia than vice versa. These results illustrate the genetic footprint of LNL-ISO on schizophrenia

A role for insulator elements in the regulation of gene expression response to hypoxia

Hypoxia inducible factor (HIF) up-regulates the transcription of a few hundred genes required for the adaptation to hypoxia. This restricted set of targets is in sharp contrast with the widespread distribution of the HIF binding motif throughout the genome. Here, we investigated the transcriptional response of GYS1 and RUVBL2 genes to hypoxia to understand the mechanisms that restrict HIF activity toward specific genes. GYS1 and RUVBL2 genes are encoded by opposite DNA strands and separated by a short intergenic region (~1 kb) that contains a functional hypoxia response element equidistant to both genes. However, hypoxia induced the expression of GYS1 gene only. Analysis of the transcriptional response of chimeric constructs derived from the intergenic region revealed an inhibitory sequence whose deletion allowed RUVBL2 induction by HIF. Enhancer blocking assays, performed in cell culture and transgenic zebrafish, confirmed the existence of an insulator element within this inhibitory region that could explain the differential regulation of GYS1 and RUVBL2 by hypoxia. Hence, in this model, the selective response to HIF is achieved with the aid of insulator elements. This is the first report suggesting a role for insulators in the regulation of differential gene expression in response to environmental signals

Importancia de las tareas educativas y del concepto situación del objeto físico en los cursos de Física

This paper defines and explains the idea of educative task in general and in a Physics course, classifying them and fixing its relation with the exercises and problems in a Physics course. It is also defined and explained the idea of physical object situation in the paper. It is exemplified and it is explained its importance in the Physics teaching and learning process.El trabajo define y explica el concepto de tarea educativa en general y en Física, clasificando las mismas y precisando su relación con los ejercicios y problemas de Física. También define y explica el concepto de situación del objeto físico. Este lo ejemplifica y plantea su importancia en el proceso de enseñanza aprendizaje de la Física

Análisis funcional de secuencias aisladoras en genomas de vertebrados: aplicaciones en biotecnología animal

Resumen del trabajo presentado al XXXVII Congreso de la Sociedad Española de Genética, celebrado en Torremolinos (Málaga) del 29 de septiembre al 2 de octubre de 2009.-- et al.El genoma se subdivide en unidades contiguas pero independientes, denominadas dominios de expresión, que contienen genes o grupos de ellos junto con los elementos necesarios para la correcta expresión de los mismos. Sorprendentemente, se ha visto que sólo un 4-5% del genoma de mamíferos está constituido por secuencias génicas, mientras que el resto son secuencias intergénicas que, además de secuencias repetitivas, contienen elementos reguladores. Entre estos elementos reguladores, destaca la presencia de los aisladores genómicos, conocidos como boundaries o insulators en inglés, cuya función es la de delimitar estructural y funcionalmente los dominios de expresión. Por un lado, los boundaries evitan las interferencias de elementos reguladores externos al dominio de expresión, asegurando la correcta expresión de los genes. Por otro lado, impiden la extensión o propagación de estados de heterocromatina adyacentes que bloquearían la expresión del dominio. Además, se ha demostrado que los boundaries contribuyen a la organización estructural del núcleo. En nuestro laboratorio se han utilizado 3 dominios de expresión diferentes de ratón como modelos de estudio de los boundaries en el genoma de mamíferos: el del locus del gen de la tirosinasa (Tyr), el del locus de la proteína ácida de la leche (Wap) y el del locus de la hormona de crecimiento (Gh). Estos 3 locus se expresan solamente en determinados tejidos y tienen una estricta regulación durante el desarrollo. A lo largo de los últimos años hemos demostrado que los boundaries de estos 3 dominios de expresión están formados por elementos diferentes desde el punto de vista estructural, pero que son funcionalmente equivalentes. Debido a que los boundaries actúan mediante diferentes mecanismos y no están relacionados desde el punto de vista estructural, continúa siendo un desafío el poder establecer estrategias que permitan predecir la existencia de nuevos boundaries en los genomas. En esta presentación resumiremos la estrategia experimental desarrollada en el laboratorio para cumplir con este objetivo. Primero las secuencias potenciales las analizamos y filtramos in vitro mediante ensayos de bloqueo de enhancer (EBA), y luego las evaluamos in vivo en experimentos de transgénesis con ratones y zebrafish; estos últimos en colaboración con el laboratorio de José Luis Gómez-Skarmeta del Centro Andaluz de Biología del Desarrollo en Sevilla.Peer reviewe