La ràdio-ensenyança

Abstract not availabl

Implementation of novel statistical procedures and other advanced approaches to improve analysis of CASA data

P. 860-866Computer-aided sperm analysis (CASA) produces a wealth of data that is frequently ignored. The use of multiparametric statistical methods can help explore these datasets, unveiling the subpopulation structure of sperm samples. In this review we analyse the significance of the internal heterogeneity of sperm samples and its relevance. We also provide a brief description of the statistical tools used for extracting sperm subpopulations from the datasets, namely unsupervised clustering (with non-hierarchical, hierarchical and two-step methods) and the most advanced supervised methods, based on machine learning. The former method has allowed exploration of subpopulation patterns in many species, whereas the latter offering further possibilities, especially considering functional studies and the practical use of subpopulation analysis. We also consider novel approaches, such as the use of geometric morphometrics or imaging flow cytometry. Finally, although the data provided by CASA systems provides valuable information on sperm samples by applying clustering analyses, there are several caveats. Protocols for capturing and analysing motility or morphometry should be standardised and adapted to each experiment, and the algorithms should be open in order to allow comparison of results between laboratories. Moreover, we must be aware of new technology that could change the paradigm for studying sperm motility and morphology.S

Continuous-time cascaded ΣΔ modulators for VDSL: A comparative study

This paper describes new cascaded continuous-time ΣΔ modulators intended to cope with very high-rate digital subscriber line specifications, i.e 12-bit resolution within a 20-MHz signal bandwidth. These modulators have been synthesized using a new methodology that is based on the direct synthesis of the whole cascaded architecture in the continuous-time domain instead of using a discrete-to-continuous time transformation as has been done in previous approaches. This method allows to place the zeroes/poles of the loop-filter transfer function in an optimal way and to reduce the number of analog components, namely, transconductors and/or amplifiers, resistors, capacitors and digital-to-analog converters. This leads to more efficient topologies in terms of circuitry complexity, power consumption and robustness with respect to circuit non-idealities. A comparison study of the synthesized architectures is done considering their sensitivity to most critical circuit error mechanisms. Time-domain behavioral simulations are shown to validate the presented approach.Ministerio de Educación y Ciencia TEC2004-01752/MI

A design tool for high-resolution high-frequency cascade continuous- time Σ∆ modulators

Event: Microtechnologies for the New Millennium, 2007, Maspalomas, Gran Canaria, SpainThis paper introduces a CAD methodology to assist the de signer in the implementation of continuous-time (CT) cas- cade Σ∆ modulators. The salient features of this methodology ar e: (a) flexible behavioral modeling for optimum accuracy- efficiency trade-offs at different stages of the top-down synthesis process; (b) direct synthesis in the continuous-time domain for minimum circuit complexity and sensitivity; a nd (c) mixed knowledge-based and optimization-based architec- tural exploration and specification transmission for enhanced circuit performance. The applicability of this methodology will be illustrated via the design of a 12 bit 20 MHz CT Σ∆ modulator in a 1.2V 130nm CMOS technology.Ministerio de Ciencia y Educación TEC2004-01752/MICMinisterio de Industria, Turismo y Comercio FIT-330100-2006-134 SPIRIT Projec

Effect of biological maturation on strength-related adaptations in young soccer players

Strength training is crucial for soccer players’ long-term development at early ages and the biological maturation may influence specific strength-training adaptations. The aim of this study was to propose a strength-training programme for the strength development of pre- pubertal players and to analyse the adaptations to this training programme in players with different maturity status. One hundred and thirty young male soccer players participated in an 8-week strength-training programme consisting of two sessions per week (20-minutes of a combination of plyometric and resistance exercises) which was conducted prior to their normal soccer training. Three maturity groups were defined according to the years from/to their peak height velocity (PHV) as Pre-, Mid- and Post-PHV. Initial differences between the maturity groups were found in anthropometrical (weight and height) and physical perfor- mance variables (One Repetition Maximum (RM), Peak Power output (PP), 30-m sprint and T-test). The strength-training programme was beneficial for the three maturity groups (p< 0.05) with general greater improvements for the Pre- and Mid-PHV groups, with large effects in RM, PP and T-test, than for the Post-PHV group (moderate effects). The strength-training programme proposed in the present study seems to be positive for the strength-related development in young soccer players especially for Pre- and Mid-PHV players. The differ- ences in the training adaptations for players with different maturity status suggest the indi- vidualization of the training stimulus for the correct long-term development of the playersSIThe authors received no specific funding for this work

Localización óptima de estaciones de medición de humedad del suelo mediante clasificaciones del relieve a partir de modelos digitales del terreno

Las formas del relieve están directamente relacionadas con los procesos ambientales que sobre ellas se desarrollan, como los hidrológicos. Para estudiar estos procesos se utilizan numerosas técnicas, como la instalación de estaciones de medición de la humedad del suelo, las cuales tienen un alto coste, tanto instrumental como asociado a su montaje. A partir de Modelos Digitales del Terreno (MDT) se han realizado una serie de análisis espaciales para obtener clasificaciones geomorfométricas de las formas del relieve. Estas clasificaciones han permitido la delimitación de áreas que pueden diferenciarse por tener una humedad edáfica distinta y por desarrollar procesos hidrológicos diferentes, según el tipo de unidad geomorfométrica que representen. De esta forma se ha facilitado la selección de zonas para la instalación de las estaciones. Los resultados se han corroborado con trabajo de campo. Esta técnica se presenta como una herramienta eficaz para la obtención de la localización potencial de zonas con distinta humedad edáfica según su posición en las áreas de estudio, lo que permite reducir el tiempo y costes asociados al trabajo de campo, y permite delimitar de antemano las áreas óptimas para la instalación de las estaciones.Landforms are directly related to environmental processes that are developed on them, such as hydrology. To study these processes many techniques are used, as installation of monitoring stations for soil moisture, which have a high cost associated with both instrumental and assembly. From Digital Terrain Models (DTM) spatial analyses have been conducted in order to obtain geomorphometric landform classifications. These classifications have allowed the delimitation of areas of different soil moisture content and hydrological processes, according to the type of geomormophetric units. This has facilitated the selection of sites for the installation of soil moisture monitoring stations. Results have been verified by fieldwork. This technique appears as an effective tool for obtaining the potential location of different soil moisture content areas reducing time and economical costs associated with fieldwork and allow defining in advance the optimal areas for soil moisture monitoring installation