Off-line incentive mechanism for long-term P2P backup storage

This paper presents a micro-payment-based incentive mechanism for long-term peer-to-peer storage systems. The main novelty of the proposed incentive mechanism is to allow users to be off-line for extended periods of time without updating or renewing their information by themselves. This feature is enabled through a digital cheque, issued by the user, which is later employed by the peers to get a gratification for storing the user's information when the user is off-line. The proposed P2P backup system also includes a secure and lightweight data verification mechanism. Moreover, the proposed incentive also contributes to improve the availability of the stored information and the scalability of the whole system. The paper details the verification and cheque-based incentive mechanisms in the context of a P2P backup service and analyzes its scalability and security properties. The system is furthermore validated by means of simulation, proving the effectiveness of the proposed incentive.This work has been funded by the Regional Government of Madrid under the MEDIANET project (S2009/TIC-1468) and has also received funding from the Ministry of Science and Innovation of Spain, under the QUARTET project (TIN2009-13992-C02-01).Publicad

Surface states on a topologically non-trivial semimetal: The case of Sb(110)

The electronic structure of Sb(110) is studied by angle-resolved photoemission spectroscopy and first-principle calculations, revealing several electronic surface states in the projected bulk band gaps around the Fermi energy. The dispersion of the states can be interpreted in terms of a strong spin-orbit splitting. The bulk band structure of Sb has the characteristics of a strong topological insulator with a Z2 invariant nu0=1. This puts constraints on the existence of metallic surface states and the expected topology of the surface Fermi contour. However, bulk Sb is a semimetal, not an insulator and these constraints are therefore partly relaxed. This relation of bulk topology and expected surface state dispersion for semimetals is discussed.Comment: 7 pages, 4 figure

Self-learning of Information Literacy Competencies in Higher Education: The Perspective of Social Sciences Students

Preference for autonomous versus directed learning for the acquisition of information competencies (ICs) was analyzed among undergraduate social science students according to gender, degree program, belief in importance, and self-efficacy. Data were gathered using the IL-HUMASS (Information Literacy Humanities Social Sciences) online survey from students at five public Spanish universities enrolled in audiovisual communication, education, information science, pedagogy, journalism, psychology, social work, and tourism undergraduate programs during the 2013–2014 academic year. Mann-Whitney U, Kruskal-Wallis, and chi-square tests, as well as discriminant analysis, were performed. The results revealed a higher preference for the directed learning style in the four IL competency categories: searching, evaluation, processing, and communication-dissemination. Audiovisual communication, education, and journalism students showed a predilection for autonomous learning, whereas information science and psychology students preferred directed learning. Higher scores in belief in importance correlated with a greater preference for autonomous learning. In contrast, higher levels of self-efficacy were associated with a greater preference for directed learning.This research is part of the national R&D Project “Innovación y formación en competencias informacionales de profesores y estudiantes universitarios de ciencias sociales” (CSO2016-80147-R), financed by MINECO

Estudio de optimización de un sistema de tracción eléctrica

El Proyecto Final de Carrera “Estudio de optimización de un sistema de tracción eléctrica.” se desarrolla en la sección eléctrica de la empresa “SENER Ingeniería y Sistemas” situada en Barcelona. El proyecto consiste en la realización de varios estudios para un mismo sistema de tracción eléctrica: un estudio eléctrico, un estudio de RAM y un estudio económico. A partir de los resultados obtenidos de forma independiente para cada uno de los estudios se realiza un análisis de conjunto de las conclusiones de cada uno de ellos. El proyecto se ha acabado centrando en un ejemplo de instalación de metro, concretamente ha tomado como base una línea de metro existente. Sin embargo, no pretende ser un estudio de esta línea de metro únicamente, sino que pretende generalizar de forma suficiente para abarcar cualquier tipo de instalación que se pueda diseñar para este medio de transporte. Se han estudiado las tipologías de subestación eléctrica de tracción más frecuentes, y todos los estudios se han hecho con todas y cada una de las configuraciones consideradas “más habituales”. El objetivo final es la obtención de la solución óptima considerando los tres parámetros: eléctrico, de fiabilidad y económico. Así pues, en función del nivel de redundancia de la instalación, del grado de disponibilidad que se requiera de ella o del horizonte económico al que se esté dispuesto a llegar, la solución puede ser una u otra y el objetivo del proyecto pretende dar esas pautas o indicaciones que permitan llegar a cada diseñador o instalador a su elección óptima

Polymer blend nanocomposites based on poly(L-lactic acid), polypropylene and WS2 inorganic nanotubes

Tungsten disulphide inorganic nanotubes (INT-WS2) have been incorporated into poly(L-lactic acid) (PLLA)/ polypropylene (PP) blends compatibilized with polypropylene-grafted-maleic anhydride (PP-g-MAH), and their effects on the morphology, thermal and mechanical properties of the resulting nanocomposites have been investigated. The nanofillers were uniformly dispersed at the nanoscale via a melt-blending process. The addition of 1.0 wt% INT-WS2 to the PLLA/PP blends hardly affected their thermal stability or their degradation mechanism. Differential scanning calorimetry (DSC) thermograms revealed the nucleating role of INT-WS2 on both polymeric components, reflected not only in an increase in the crystallization temperature from the melt but also in a rise in the crystallization enthalpy and the suppression of the cold-crystallization process; this effect was found to be more pronounced on PLLA and the blends rich in this component. Dynamic mechanical analysis (DMA) measurements demonstrated that the storage modulus of the nanocomposites was higher than those of the binary blends in the whole temperature range studied, ascribed to a synergistic effect of their increased crystallinity and the high INT-WS2 rigidity. This study opens up new perspectives to develop novel INTWS2/polymer blend hybrid nanocomposites that show great potential for biomedical applications

Monitorización de las cargas de entrenamiento en corredores de fondo y medio fondo de alto nivel

El principal objetivo del entrenamiento consiste en mejorar el rendimiento y, por ende, reducir lesiones. Para ello, la monitorización de dicha carga (interna, externa y su relación) se ha constatado como vital. Sin embargo, muchos entrenadores siguen sin controlar (o etéreamente) las cargas en sus deportistas, pues, además, no existe un sistema etiquetado como el ideal. Consecuentemente, teniendo en cuenta el contexto y lo que la literatura dice al respecto, se realizó una propuesta personal con corredores de resistencia de alto nivel, contabilizando, en cuanto a carga externa, volumen mediante los kilómetros recorridos semanalmente, intensidad mediante la velocidad de carrera con zonas de entrenamiento en función del perfil individual de lactato, y frecuencia registrando el número de entrenamientos y de los contenidos trabajados. Respecto al estrés interno, la Escala de Esfuerzo Percibido y la medición de la altura del salto vertical con contramovimiento, en pos de determinar la fatiga neuromuscular subaguda. Los resultados mostraron relación significativa en la mayoría de variables, haciendo que el objetivo e hipótesis que perseguía la intervención se cumplan en mayor o menor medida, por lo que el sistema de monitorización escogido y/o los diferentes ítems que lo componen podrían ser válidos para su utilización en otros contextos.The main objective of training is to improve performance and, therefore, reduce injuries. For that reason, the monitoring of this load (internal, external and their relationship) has been verified as vital. However, many trainers still do not control (or ethereally) the loads on their athletes. In addition, there is not system labeled as the ideal. Consequently, taking into account the context and what the literature says about it, a personal research was made with high-level resistance runners, accounting, in terms of external load, volume through the kilometers traveled weekly, intensity through the running speed with training zones depending on the individual lactate profile, and frequency recording the number of training sessions and the contents worked. Regarding internal stress, the Rating of Perceived Exertion and a measurement of countermovement jump height, in order to determine subacute neuromuscular fatigue. The results showed a significant relationship in most variables, making the objective and hypothesis of the intervention have been met to a greater or lesser extent, so that the chosen monitoring system and / or the different items that comprise it could be valid for its use in other contexts.info:eu-repo/semantics/publishedVersio

Análisis del golpeo y la preparación psicológica para retornar a la práctica en futbolistas tras una lesión isquiosural

Las lesiones de la musculatura isquiosural son las más comunes en fútbol, y pueden presentar efectos residuales que cambien el patrón de un gesto técnico. El presente estudio analizó las diferencias en la técnica de golpeo entre jugadores anteriormente lesionados y jugadores no lesionados, así como las correlaciones entre la capacidad psicológica para retornar a la práctica y las características del gesto. Tres futbolistas que habían padecido una lesión de isquiosurales conformaron el grupo de jugadores anteriormente lesionados, y tres futbolistas que no habían padecido ninguna lesión en el miembro inferior en los últimos dos años, formaron el grupo de jugadores no lesionados. Se analizaron los gestos de golpeo a balón parado y de golpeo en carrera a través del programa Kinovea. Asimismo, se evaluó la capacidad psicológica para retornar a la práctica mediante el Injury Psychological Readiness to Return to Sport (I-PRRS). Únicamente la velocidad del balón en el golpeo en carrera presentó diferencias significativas entre grupos (p<0,05). Además, se obtuvieron correlaciones positivas entre la preparación psicológica para retornar y la flexión de rodilla en el golpeo en carrera, y entre la flexión de rodilla en el golpeo a balón parado y los ítems 3 y 4 del I-PRRS. Asimismo, se hallaron correlaciones negativas entre la extensión de cadera en el golpeo a balón parado y el ítem 6 del I-PRRS. Los resultados permiten concluir que variables cinemáticas y variables psicológicas se encuentran interrelacionadas tras una lesión en la musculatura isquiosural.info:eu-repo/semantics/publishedVersio

Effect of restricted feeding under rearing on reproduction, body condition and blood metabolites of rabbit does selected for growth rate

[EN] Young rabbit females selected for growth rate can have nutritional needs which may not be met by the common practice of feed restriction during rearing in commercial rabbit production. The aim of this study was to analyse the effect of two different feeding programmes: restricted and ad libitum feeding, applied in young rabbit females for one month at the end of rearing, on reproductive performance, body condition and circulating metabolic hormones and metabolites in a rabbit line selected by growth rate in 3 consecutive reproductive cycles. Thus, twenty-four 16-week-old does were randomly assigned to a group in which the daily recommended nutrient intakes were satisfied (fed restricted: 130 g/day, n=13) or a group fed to satiety (ad libitum: 235.5 g/day, n=11) during one month. Then, all does were inseminated in 3 consecutive cycles using a 42-day reproductive cycle. Measurements of does’ body weight, perirenal fat thickness and plasma leptin, non-esterified-fatty-acids (NEFA), beta-hydroxybutyrate (BOHB) and fructosamine were performed at artificial insemination (AI), parturition and weaning time in 3 consecutive cycles. Reproductive performance of does was evaluated based on fertility, litter size at parturition, prolificacy and productivity. Differences in body weight were found only in the 1st cycle, ad libitum fed females being heavier than restricted ones. Nevertheless, body weight variances disappeared in later cycles. No differences were found in perirenal fat thickness. Finally, in ad libitum fed females slight differences were found in plasma levels of NEFAs (452 vs. 258 μekv/L and 527 vs. 306 μekv/L for 1st and 2nd cycles) and BOHB (0.26 vs. 0.03 mM for 2nd cycle), but disappeared in the 3rd reproductive cycle. Fertility, prolificacy and productivity was not significantly affected by the feeding programme. Nevertheless, total litter size showed to be higher in ad libitum fed females at second parturition (8.7 vs. 5.9 kits). Therefore, the evaluated feeding programmes until first AI in females selected by growth rate had no effect on their reproductive outcomes, as the global reproductive performance was not affected.This work was supported by the Spanish Research Project AGL2014- 53405-C2-1-P (CICYT). Carmen Naturil was supported by a research grant from the Education Ministry of the Valencian Regional Government (programme VALi+d. ACIF ⁄ 2013 ⁄ 296). English text version revised by N. Macowan English Language Service.Naturil-Alfonso, C.; Marco-Jiménez, F.; Pascual, J.; Vicente, J. (2017). Effect of restricted feeding under rearing on reproduction, body condition and blood metabolites of rabbit does selected for growth rate. World Rabbit Science. 25(4):303-312. https://doi.org/10.4995/wrs.2017.6848SWORD30331225