Torsion homology and cellular approximation

We describe the role of the Schur multiplier in the structure of the p-torsion of discrete groups. More concretely, we show how the knowledge of H2G allows us to approximate many groups by colimits of copies of p-groups. Our examples include interesting families of noncommutative infinite groups, including Burnside groups, certain solvable groups and branch groups. We also provide a counterexample for a conjecture of Emmanuel Farjoun.Fondo Europeo de Desarrollo RegionalMinisterio de Ciencia e InnovaciónConsejería de Economía, Innovación y Ciencia (Junta de Andalucía

Effect of Vinyl Flooring on the Modal Properties of a Steel Footbridge

Damping ratios associated with non structural elements play an important role in mitigating the pedestrian-induced vibrations of slender footbridges. In particular, this paper analyses the effect of vinyl flooring on the modal parameters of steel footbridges. Motivated by the unexpected high experimental damping ratios of the first vibration modes of a real footbridge, whose deck was covered by a vinyl flooring, this paper aims at assessing more accurately the experimental damping ratios generated by this non-structural element on steel footbridges. For this purpose, a laboratory footbridge was built and vinyl flooring was installed on it. Its numerical and experimental modal parameters without and with the vinyl flooring were determined. The operational modal analysis method was used to estimate experimentally the modal parameters of the structure. The damping ratios associated with the vinyl flooring were obtained via the substraction between the experimental damping ratios of the laboratory footbridge with and without the vinyl flooring. An average increase of the damping ratios of 2.069% was observed due to the vinyl flooring installed. According to this result, this type of pavement may be a useful tool to significantly increase the damping ratios of steel footbridges in order to reduce pedestrian-induced vibrationsMinisterio de Economía y Competitividad DPI2014-53947-RFondo Europeo de Desarrollo Regional DPI2014-53947-

Estudio descriptivo y valoración del gasto energético en actividades militares de combate simulado

Son escasos los estudios que analizan poblaciones físicamente activas como la militar. Además en el ejército español no se ha realizado este tipo de estudio en el que se simula la realización de un combate con todo el equipo. Por otra parte, la incorporación de la mujera a las Fuerzas Armadas, el nuevo carácter profesional de la tropa y la participación de nuestro ejército en conflictos internacionales obliga a un conocimiento más profundo del grado de enfrentamiento físico de nuestros soldados. Por todo ello se propone como objetivo final: Aportar un mayor grado de conocimiento sobre el esfuerzo de tales maniobras que suponen un éxito profesional y vital, para así contribuir a la mejora de la misma de acuerdo a los dispuesto en el artículo 44 de la Reales Ordenanzas para las Fuerzas Armadas que sobre la forma física del personal militar dice: ".. Es necesario una adecuada preparación física que le permita cumplir sus misiones con la bebida competencia y actuar con eficacia en el combate". Utilizando una muestra de 27 soldados profesionales (19 varones y 8 mujeres) destinados en la Brigada de Infantería Mecanizada Córdoba X con sede en Centro Muriano (Córdoba), se lleva a cabo un estudio cineantropométrico, y una prueba de esfuerzo máxima en tapiz. Una semana más tarde se realiza una prueba en tapiz con la ropa de instrucción, el equipo de combate y el armamento (Peso del equipo completo: 26.170 kg) simulando una maniobra de combate de una compañía de infantería ligera en su fase de aproximación desde los 1500 metros hasta la línea de fuego enemigo. Analizando los resultados podemos resaltar que la capacidad de trabajo físico del soldado presenta un valor medio de 51.1 ml/kg/min coincidiendo con el encontrado en la mayoría de estudios realizados con poblaciones militares. Se confirma que la muestra estudiada presenta una buena capacidad aeróbica a pesar de que se encontraban en una fase sedentaria desarrollando tareas militares en el acuartelamiento y sin tratamiento específico, en un período a una fase de campaña de 6 meses de duración (guerra de Bosnia).En función del sexo los parámetros ergoespirométricos alcanzan valores más altos en los soldados masculinos a excepción de la FC que durante las fases 2,3 y 4 alcanzan cifras superiores en los soldados femeninos, posiblemente relacionados con la influencia del peso del equipo sobre una población con un peso graso mucho más elevado. Sería necesario realizar un entrenamiento adecuado en función del sexo que permita mantener una igualdad en la condición física de los soldados y poder ejecutar las acciones del combate de forma homogénea y precisa. Por tanto comparando los parámetros cardiorespiratorios y metabólicos durante las cuatro fases de la maniobra protocolizada, se produce un claro aumento en las tres primeras fases (en relación con la intensidad del esfuerzo) y una disminución en la fase 4 relacionada con la falta de recuperación y la fatiga progresiva. Por todo ello se considera de gran importancia: A,- Modificar este protocolo, ya sea acortando las distancias de las series o aumentando el tiempo de recuperación entre ellas, para facilitar una reducción de la fatiga que permita al soldado llegar a las posiciones enemigas donde se producirá el combate cuerpo a cuerpo, en las mejores condiciones fisiológicas posibles. B,- O mejorar la preparación física en base a programas de entrenamiento que aumenten la capacidad aeróbica y la fuerza y resistencia muscular para transportar el equipo de combate de 26 kg.1320731

Lesiones musculares en el deporte. Muscular injuries in sport.

ResumenDurante la práctica de la actividad física hay una gran incidencia de lesiones musculares, si bien se han llevado a cabo pocos estudios clínicos sobre el tratamiento y la resolución de las mismas. Desde el punto de vista etiopatogénico, hay que señalar que la incidencia de lesión es mayor en aquellos músculos poliarticulares en condiciones de acumulación de fatiga y con condiciones ambientales desfavorables. La clasificación de las lesiones musculares permite distinguir entre aquellas que no afectan a la fascia produciéndose un sangrado dentro del mismo (intramuscular) o bien si la fascia también se rompe, el sangrado se sitúa entre los diferentes músculos (intermuscular). El tratamiento de estas lesiones se realizará combinando reposo, compresión, aplicación de frío y elevación del área lesionada así como el desarrollo de un adecuado programa de readaptación funcional que permita al jugador incorporarse lo antes posible a la dinámica del equipo. En la actualidad se está llevando a cabo opciones terapéuticas con factores de crecimiento, terapia génica y células madre, si bien todavía no están lo suficientemente desarrolladas.AbstractDuring the practice of the physical activity there is a great effect of muscular injuries, though few clinical studies have been carried out on the treatment and the resolution of the same ones. Inside the reasons it is necessary to indicate that the effect of injury is major in those muscles you will polyarticulate in situation of fatigue and with environmental unfavorable conditions.The classification of the muscular injuries allows to distinguish between those that do not affect the fascia producing the bled intramuscular or if the fascia also breaks, the bled one places between the different muscles (intermuscular).The treatment will be realized combining rest, compression, application of cold and elevation of these injuries as well as the development of a program of functional readaptation that allows to the player to join as soon as possible to the dynamics of the team. At present therapeutic options are carried out by factors of growth, therapy genetic and cells mother, though still they are not sufficiently developed

Standard compliant flicker reduction method with PSNR loss control

Proceedings: EEE International Conference on Acoustics, Speech and Signal Processing (ICASSP2013). Vancouver, Canada, May 26-31, 2013Flicker is a common video coding artifact that occurs especially at low and medium bit rates. In this paper we propose a temporal filter-based method to reduce flicker. The proposed method has been designed to be compliant with conventional video coding standards, i.e., to generate a bitstream that is decodable by any standard decoder implementation. The aim of the proposed method is to make the luminance changes between consecutive frames smoother on a block-by-block basis. To this end, a selective temporal low-pass filtering is proposed that smooths these luminance changes on flicker-prone blocks. Furthermore, since the low-pass filtering can incur in a noticeable blurring effect, an adaptive algorithm that allows for limiting the PSNR loss -and thus the blur-has also been designed. The proposed method has been extensively assessed on the reference software of the H.264/AVC video coding standard and compared to a state-of-the-art method. The experimental results show the effectiveness of the proposed method and prove that its performance is superior to that of the state-of-the-art method.Publicad

Mode Decision-Based Algorithm for Complexity Control in H.264/AVC

The latest H.264/AVC video coding standard achieves high compression rates in exchange for high computational complexity. Nowadays, however, many application scenarios require the encoder to meet some complexity constraints. This paper proposes a novel complexity control method that relies on a hypothesis testing that can handle time-variant content and target complexities. Specifically, it is based on a binary hypothesis testing that decides, on a macroblock basis, whether to use a low-or a high-complexity coding model. Gaussian statistics are assumed so that the probability density functions involved in the hypothesis testing can be easily adapted. The decision threshold is also adapted according to the deviation between the actual and the target complexities. The proposed method is implemented on the H.264/AVC reference software JM10.2 and compared with a state-of-the-art method. Our experimental results prove that the proposed method achieves a better trade-off between complexity control and coding efficiency. Furthermore, it leads to a lower deviation from the target complexity.This work has been partially supported by the National Grant TEC2011-26807 of the Spanish Ministry of Science and Innovation.Publicad

Bayesian adaptive algorithm for fast coding unit decision in the High Efficiency Video Coding (HEVC) standard

The latest High Efficiency Video Coding standard (HEVC) provides a set of new coding tools to achieve a significantly higher coding efficiency than previous standards. In this standard, the pixels are first grouped into Coding Units (CU), then Prediction Units (PU), and finally Transform Units (TU). All these coding levels are organized into a quadtree-shaped arrangement that allows highly flexible data representation; however, they involve a very high computational complexity. In this paper, we propose an effective early CU depth decision algorithm to reduce the encoder complexity. Our proposal is based on a hierarchical approach, in which a hypothesis test is designed to make a decision at every CU depth, where the algorithm either produces an early termination or decides to evaluate the subsequent depth level. Moreover, the proposed method is able to adaptively estimate the parameters that define each hypothesis test, so that it adapts its behavior to the variable contents of the video sequences. The proposed method has been extensively tested, and the experimental results show that our proposal outperforms several state-of-the-art methods, achieving a significant reduction of the computational complexity (36.5% and 38.2% average reductions in coding time for two different encoder configurations) in exchange for very slight losses in coding performance (1.7% and 0.8% average bit rate increments).This work has been partially supported by the National Grant TEC2014-53390-P of the Spanish Ministry of Economy and Competitiveness

Developing Efficient Discrete Simulations on Multicore and GPU Architectures

In this paper we show how to efficiently implement parallel discrete simulations on multicoreandGPUarchitecturesthrougharealexampleofanapplication: acellularautomatamodel of laser dynamics. We describe the techniques employed to build and optimize the implementations using OpenMP and CUDA frameworks. We have evaluated the performance on two different hardware platforms that represent different target market segments: high-end platforms for scientific computing, using an Intel Xeon Platinum 8259CL server with 48 cores, and also an NVIDIA Tesla V100GPU,bothrunningonAmazonWebServer(AWS)Cloud;and on a consumer-oriented platform, using an Intel Core i9 9900k CPU and an NVIDIA GeForce GTX 1050 TI GPU. Performance results were compared and analyzed in detail. We show that excellent performance and scalability can be obtained in both platforms, and we extract some important issues that imply a performance degradation for them. We also found that current multicore CPUs with large core numbers can bring a performance very near to that of GPUs, and even identical in some cases.Ministerio de Economía, Industria y Competitividad, Gobierno de España (MINECO), and the Agencia Estatal de Investigación (AEI) of Spain, cofinanced by FEDER funds (EU) TIN2017-89842

Standard-Compliant Low-Pass Temporal Filter to Reduce the Perceived Flicker Artifact

Flicker is a common video-compression-related temporal artifact. It occurs when co-located regions of consecutive frames are not encoded in a consistent manner, especially when Intra frames are periodically inserted at low and medium bit rates. In this paper we propose a flicker reduction method which aims to make the luminance changes between pixels in the same area of consecutive frames less noticeable. To this end, a temporal low-pass filtering is proposed that smooths these luminance changes on a block-by-block basis. The proposed method has some advantages compared to another state-of-the-art methods. It has been designed to be compliant with conventional video coding standards, i.e., to generate a bitstream that is decodable by any standard decoder implementation. The filter strength is estimated on-the-fly to limit the PSNR loss and thus the appearance of a noticeable blurring effect. The proposed method has been implemented on the H. 264/AVC reference software and thoroughly assessed in comparison to a couple of state-of-the-art methods. The flicker reduction achieved by the proposed method (calculated using an objective measurement) is notably higher than that of compared methods: 18.78% versus 5.32% and 31.96% versus 8.34%, in exchange of some slight losses in terms of coding efficiency. In terms of subjective quality, the proposed method is perceived more than two times better than the compared methods.This work has been partially supported by the National Grant TEC2011-26807 of the Spanish Ministry of Science and Innovation.Publicad