La "máquina" o "generador" de terremotos en un laboratorio universitario

La máquina o generador de terremotos es un dispositivo experimental que trata de modelizar el comportamiento de una falla. En la actividad propuesta, se le muestra al alumnado la complejidad de ciertos sistemas, así como la dificultad de predecir su comportamiento. Aunque inicialmente se postuló como un experimento abierto dirigido a estudiantes de enseñanza secundaria y bachillerato, la calidad de los datos que pueden obtenerse permite que pueda plantearse como un experimento en unlaboratorio universitario de ciencias de la Tierra. Los datos obtenidos en una experiencia de este tipo pueden ser equiparables, en cierto sentido, a los datos obtenidos por redes sísmicas regionales, en especial, los datos referentes a la sismicidad generada por una falla o sistema de fallas, en términos de magnitud, tiempo y caída de esfuerzos. Eso sí, con la clara ventaja de que en pocos minutos puede reproducirse lo que serían cientos o miles de años de acción de las fuerzas tectónicas. En función del nivel del curso en el que se proponga dicha experiencia, planteándose en este caso como una experiencia cerrada centrada en la obtención de determinados resultados, se pueden utilizar diferentes análisis de datos, fundamentalmente de tipo estadístico. Estos análisis permitirán conocer el nivel de predictibilidad de un modelo de estas características. Este trabajo plantea diferentes métodos y analiza los resultados que pueden obtenerse con este modelo mecánic

Utilización de ansiolíticos e hipnóticos en España (1995-2002)

Producción CientíficaFundamento: Estudios recientes han señalado un aumento en el consumo de ansiolíticos e hipnóticos, así como su uso inadecuado, en países occidentales. El objetivo de este trabajo es conocer su patrón de utilización en España entre los años 1995 y 2002. Métodos: Los datos de consumo de medicamentos se obtuvieron de la base de datos ECOM (Especialidades Consumo de Medicamentos) del Ministerio de Sanidad y Consumo, que contiene información sobre el consumo de medicamentos dispensados con cargo al Sistema Nacional de Salud en farmacias comunitarias. Los datos se expresaron en Dosis Diarias Definidas por 1.000 habitantes y día. Resultados: La utilización de ansiolíticos e hipnóticos creció desde 39,71 Dosis Diarias Definidas por 1.000 habitantes y día en 1995 a 62,02 en 2002. A lo largo del periodo estudiado las benzodiazepinas de vida media intermedia (8-24 horas) fueron los medicamentos más utilizados, en especial lorazepam, alprazolam y lormetazepam. El principio activo que más disminuyó su consumo fue el flunitrazepam. Conclusiones: Aunque el consumo de ansiolíticos e hipnóticos en España experimentó un notable incremento en los últimos años, el patrón de consumo no presentó modificaciones sustanciales

A new geometrical method for 3D evaluation of non-rigid registration methods for radiotherapy in prostate cancer

Three-dimensional conformal radiotherapy aims at delivering a high dose of radiation to the tumour, while sparing the surrounding normal tissue to a maximum extent. Image registration is an essential tool for monitoring radiation therapies, since allows morphological comparisons in presence of anatomic variations. The evaluation of non-rigid registration methods is very complicated owe to the absence of a known pointwise correspondence. The use of analysis of variations in target volume delineations has been proposed in the past for the evaluation of non-rigid registration methods. Delineation of the target volume is usually accomplished by outlining the contour of the volume in each separate tomographic slice. In the studies of reference, the 3D surface is rendered from the contours by means of a Delauney triangulation. This geometrical method only works correctly for convex structures. However the volumes involved on pelvic anatomy, such as bladder or prostate including the seminal vesicles, have relevant concavities that introduce a huge error in the evaluation. A new geometrical method for the evaluation of convex-concave target volumes delineation is proposed

Mathematical modelling of neural processes within the oculomotor system

It is presented a mathematical model of the oculomotor plant, based on experimental data in cats. The system that generates, from the neuronal processes at the motoneuron, the control signals to the eye muscles that moves the eye. In contrast with previous models, that base the eye movement related motoneuron behavior on a first order linear differential equation, non-linear effects are described: A dependency on the eye angular position of the model parameters

Experimental response of agglomerated cork under multi-impact loads

In contrast to other cellular materials, which deform by crushing under impact and develop permanent deformation, agglomerated cork has a viscoelastic response and is environmentally friendly; therefore, it could be a good alternative to be used in engineering applications subjected to more than one impact, and thus further understanding of the energy-absorption capabilities of this material under multi-impact conditions is needed. In this work the multi-impact behaviour of agglomerated cork was studied experimentally by performing several consecutive impacts in a drop-weight tower on specimens of different thickness and at two impact energy levels. The maximum contact force, maximum strain, and the absorbed energy were evaluated in each test. The results show the great capability of agglomerated cork to continue absorbing energy after several consecutive impacts.Publicad

Frailty is associated with objectively assessed sedentary behaviour patterns in older adults: Evidence from the Toledo Study for Healthy Aging (TSHA)

Objective: The aim of this study was to examine the association of sedentary behaviour patterns with frailty in older people. Setting: Clinical setting. Design: Cross-sectional, observational study. Participants and measurements: A triaxial accelerometer was used in a subsample from the Toledo Study for Healthy Aging (519 participants, 67–97 years) to assess several sedentary behaviour patterns including sedentary time per day, the number and duration (min) of breaks in sedentary time per day, and the proportion of the day spent in sedentary bouts of 10 minutes or more. Frailty was assessed using the Frailty Trait Scale (FTS). Regression analysis was used to ascertain the associations between sedentary behaviour patterns and frailty. Results: Sedentary time per day and the proportion of the day spent in sedentary bouts of 10 minutes or more, were positively associated with frailty in the study sample. Conversely, the time spent in breaks in sedentary time was negatively associated with frailty. Conclusion: In summary, breaking up sedentary time and time spent in sedentary behaviour are associated with frailty in older people

Automated FISH spots counting in interphase nuclei

ABSTRACT NUMBER 197Work supported by grant CYCIT (TIC92-0922)

The Effect of Cholesterol on the Long-Range Network of Interactions Established among Sea Anemone Sticholysin II Residues at the Water-Membrane Interface

Actinoporins are α-pore forming proteins with therapeutic potential, produced by sea anemones. Sticholysin II (StnII) from Stichodactyla helianthus is one of its most extensively characterized members. These proteins remain stably folded in water, but upon interaction with lipid bilayers, they oligomerize to form a pore. This event is triggered by the presence of sphingomyelin (SM), but cholesterol (Chol) facilitates pore formation. Membrane attachment and pore formation require changes involving long-distance rearrangements of residues located at the protein-membrane interface. The influence of Chol on membrane recognition, oligomerization, and/or pore formation is now studied using StnII variants, which are characterized in terms of their ability to interact with model membranes in the presence or absence of Chol. The results obtained frame Chol not only as an important partner for SM for functional membrane recognition but also as a molecule which significantly reduces the structural requirements for the mentioned conformational rearrangements to occur. However, given that the DOPC:SM:Chol vesicles employed display phase coexistence and have domain boundaries, the observed effects could be also due to the presence of these different phases on the membrane. In addition, it is also shown that the Arg51 guanidinium group is strictly required for membrane recognition, independently of the presence of Chol

A new method for quantitative evaluation of target volume variations in radiotherapy planning

A new method for three-dimensional quantitative evaluation of target volume delineation is presented. It is composed by a new 3D reconstruction method called Origami, based on the combination of two bidimensional analysis of the volume of each organ instead of one 3D analysis, and a 3D description of the error distribution in the space. The Origami method avoid external errors introduced by a 3D rendering and has shown to work correctly in both convex and convex-concave volumes, accurately fitting the contours of the planning study. Its performance has been evaluated comparing it with the Convex Hull algorithm using Delaunay triangulation, resulting in a much more adjusted evaluation. Moreover, Origami computes thousands of control points in less than one second in a common PC

Método de evaluación cuantitativa de algoritmos de registro tridimensional deformable

Se presenta una nueva metodología de evaluación cuantitativa de algoritmos de registro tridimensional deformable basada en las delineaciones de los órganos de interés. Esta metodología ofrece una completa descripción tridimensional del error de registro mediante el cálculo de las distancias entre los volúmenes del órgano de interés en la imagen de referencia y la imagen registrada. El método propuesto ha demostrado la capacidad de trabajar correctamente tanto en volúmenes totalmente convexos como en volúmenes cóncavo-convexos, ajustándose de manera precisa a los volúmenes marcados por el especialista. Además, el alto rendimiento del método permite la rápida evaluación en un gran número de direcciones de control (64800 direcciones en menos de un segundo