Differences in kicking velocity and kicking deficit in young elite soccer players

El objetivo de este estudio fue examinar la evolución del rendimiento máximo de golpeo de balón a lo largo de la edad en futbolistas jóvenes de élite. Un total de 175 fueron divididos en 11 grupos edad (U-9 hasta U-19), además del equipo filial del club (U-23). Se registró la velocidad máxima de golpeo con la pierna dominante y no dominante mediante radar. El déficit de golpeo fue calculado para comparar el rendimiento entre ambas piernas. La velocidad máxima de golpeo aumenta progresivamente de forma significativa desde U-9 hasta U-16 con la pierna dominante y hasta U-18 con la no dominante, y sigue aumentando de forma no significativa hasta U-23. La etapa con mayor incremento de la velocidad de golpeo fue entre U-13 y U-16. Existe un déficit de golpeo con la pierna no dominante y sus valores permanecen estables (9.43%-18.18%) sin cambios significativos desde U-9 hasta U-23The purpose of this current study was to examine the age-related differences in kicking performance with both legs in 175 youth soccer players. Players from the development programme of a professional club were grouped according to their respective under-age team (U-9 to U-18), in addition to the club’s second team (U-23). Maximal kicking velocity with the preferred and non-preferred leg was recorded using a Doppler radar gun. Kicking deficit was calculated to compare side-to-side performance. Maximal kicking velocity improved progressively from the U-9 to U-16 age groups for the preferred leg and from U-16 to U-18 for the non-preferred leg, and continued to improve moderately but non-statistically significant until U-23. The stage of greatest kicking velocity development was between 13 and 16 years of age. There is a kicking deficit with the non-preferred leg and its values remain steady (9.43%-18.18%) without significant changes in players from U-9 to U-23 categorie

Effect of calcium carbonate addition to helix aspersa müller diet

In this paper is studied the effect of calcium carbonate addition to diet on growth, mortality rate and feed intake of snails Helix aspersa Müller during the juvenile stage under laboratory conditions. Two treatments have been tested; first one with 12.5 percent and second one with 22.5 percent of calcium carbonate. Five groups of 40 snails have been randomly assigned to each treatment. Results show significant (p<0.05) differences between both treatments; in the second one is obtained a higher growth and lower mortality rate; however there is no significant difference for dry matter intake.En el presente trabajo se estudia el efecto de la adición de carbonato de calcio a la dieta sobre el crecimiento, mortalidad y consumo del caracol Helix aspersa Müller durante la fase de alevinaje y en condiciones de laboratorio. Se plantean dos tratamientos; el I con 12,5 p.100 y el II con 22,5 p.100 de carbonato cálcico. A cada tratamiento se le asignan aleatoriamente cinco lotes de 40 animales. Los resultados muestran diferencias significativas (p<0,05) entre ambos tratamientos; obteniéndose con el tratamiento II mayor crecimiento y menor mortalidad; que no se aprecian diferencias significativas respecto al consumo de materia seca

Effect of population density on size of edible snail helix aspersa müller

An assessment was made of the effects of population density on Helix aspersa Müller snails at their nursery stage. A sample of 3420 animals was used, grouped at eighteen density levels: from 600 to 11100 snails/m2. The results demonstrate that higher population density decreased growth (p<0.001). Furthermore the optimum snail population density at the nursery stage ranged from 600 to 4300 snails/m2.Se estudia el efecto de la densidad sobre el tamaño del Helix aspersa Müller durante la primera fase de crecimiento. Se utilizan 18 niveles de densidad entre 600 a 11100 animales/m2. Los resultados indican la existencia de diferencias significativas en el crecimiento según el nivel de densidad (p<0,001), de modo que a medida que se incrementa la densidad disminuye el tamaño. La densidad óptima, en primera edad, oscila entre 600 y 4300 animales/m2

RAEA-Heliciculture: mechanism of conservation and rural development in Andalusia

The fast growth system is a snail rearing method with a high degree of technification. Actually, the experimental evaluation of the system is being developed by an Andalusian Network of Agrarian Research (RAEA-Heliciculture) on commercial farms. The aim of this study was to compare the fast growth and the intensive systems in juvenile Helix aspersa snails. The growth and the growth patterns are studied in 5 groups of 60 H. aspersa snails reared with both systems. The snails reared with the fast growth system reached a high weight (0.956 g) and a low variability (13%). The growth rate with the fast growth system showed the best fit to exponential model, while the growth rate with the intensive system showed good fit to logistic model.El sistema de pronto engorde es una especialización productiva en la fase de crecimiento y engorde de Helix aspersa con alto nivel de tecnificación. Actualmente se está desarrollando su evaluación experimental en granjas comerciales, a través de una Red Andaluza de Experimentación Agraria (RAEA-Helicicultura). Con el objetivo de comparar el sistema de pronto engorde frente al intensivo, se estudia el crecimiento y su modelización en 5 lotes de 60 caracoles H. aspersa criados con ambos sistemas durante la fase juvenil. Los resultados muestran que los caracoles del sistema de pronto engorde alcanzan el peso más alto con 0,956 g y la menor variabilidad (13%). El crecimiento con el pronto engorde se ajusta a un modelo exponencial, mientras que el sistema intensivo muestra mayor bondad en el ajuste con el modelo logístico

Experimental conditions for microhabitat selection in terrestrial snails

Habitat selection by terrestrial snails, used as laboratory animals, is an important factor because it can alter growth rates often used as a good biological indicator, moreover of its productive meaning. As support to the studies in this field, different models from election of microhabitat based on the individual selection or derived from other questions as the availability or the accessibility of the habitat or patron of movement of the organism are reviewed. Finally two experimental designs used in invertebrates under laboratorial conditions for preference studies are considered.La selección de hábitat por los caracoles terrestres que se utilizan como animales de experimentación, es importante porque condiciona el crecimiento y éste, además de su importancia productiva, es un buen indicador en muchos estudios. Como apoyo a los estudios en este campo, se revisan diferentes modelos de elección de microhábitat en función de la selección del propio individuo o bien derivados de cuestiones en buena parte ajenas a él como la disponibilidad o accesibilidad del hábitat o el patrón de movimiento del organismo. Finalmente se plantean dos diseños experimentales adecuados para el estudio de preferencia en invertebrados bajo condiciones de laboratorio

Malacological diversity in Andalusia. Renewable resource

The aim of this study is the evaluation of malacological diversity in Andalusian region. It has been observed high heterogeneity in relation to distribution patters of snails. Terrestrial edible snail populations are grouped in zones in relation to spatial distribution and specie. Zone I is located in Sierra Morena and shows a low density level of the most commonly edible species (O. lactea, H. aspersa, T. pisana and E. vermiculata). Zone II is extended throughout La Campiña and Vega del Guadalquivir. This zone is widely populated by snails with great economically importance: O. lactea and T. pisana and H. aspersa with a smaller density. Zone III is located in Sierras Béticas and it is characterised by the presence of many endemic populations (O. lactea murcica, O. punctata, T. pisana arietina, T. subdentata helicella, C. nemoralis, I. gualtierianus gualtierianus, I. gualtierianus alonensis, I. gualtierianus guiraoanus, etc.). It is necessary to develop strategic plans in order to conserve the malacological diversity in Andalusia.El objetivo del estudio es la evaluación de la diversidad malacológica andaluza como base del aprovechamiento de un recurso genético de interés económico. Se zonifican las poblaciones de caracoles comestibles existentes en Andalucía en relación al número de especies y su distribución geográfica. Se observa elevada heterogeneidad que da lugar a la conformación de tres zonas diferenciadas, en las que aparecen fundamentalmente los géneros Otala, Theba, Cantareus, Iberus, Eobania, Cepaea, Pseudotachea y Sphincterochila. La Zona I comprende Sierra Morena y se caracteriza por una baja presencia de caracoles, asociados mayoritariamente a la presencia humana y representados por las especies más comunes (O. lactea, H. aspersa, T. pisana y E. vermiculata). La Zona II comprende la Campiña y Vega del Guadalquivir, donde aparecen las especies de mayor valor comercial: O. lactea y T. pisana, con gran distribución; y H. aspersa con menor presencia. Finalmente la Zona III, que se integra por las Sierras Béticas donde aparecen, junto con las especies anteriormente citadas, gran diversidad de taxones con elevada singularidad, debido a la existencia de un número importante de endemismos y poblaciones relictas (O. lactea murcica, O. punctata, T. pisana arietina, T. subdentata helicella, C. nemoralis, I. gualtierianus gualtierianus, I. gualtierianus alonensis, I. gualtierianus guiraoanus, etc.). La existencia de esta biodiversidad justifica la necesidad de adoptar acciones estratégicas y planes específicos de conservación que preserven este recurso de forma eficaz

Habitat selection in terrestrial snails and its applications to heliciculture

Snails are employed as experimental animals in different scientific fields and their growth is a good biological indicator. Growth is mainly determined at a genetic level, although many factors biotic and abiotic may alter growth rates. One of these factors is habitat selection. Nevertheless the knowledge about the cha-racteristics that determines habitat selection are not considered in the design of installations, management of farms or raising snails. In this way, the aim of this paper is synthesize the different components of habitat that influence habitat choice of terrestrial snails. On the other hand, it proposes premises that would be considered in design of installations.El crecimiento de los caracoles terrestres que, además de como animales productivos, se utilizan como animales de experimentación es considerado un buen indicador biológico. Aunque el crecimiento está genéticamente determinado, muchos factores pueden modificarlo, uno de ellos es la selección de hábitat. Sin embargo, los conocimientos sobre las condiciones que la determinan no se suelen incorporar al diseño de instalaciones, manejo de los criaderos o la producción helicícola. En este trabajo se revisan aquellas condiciones que determinan la selección de microhábitat en caracoles terrestres y se proponen medidas que deberían ser consideradas en el diseño de instalaciones

Pulsar-wind nebulae and magnetar outflows: observations at radio, X-ray, and gamma-ray wavelengths

We review observations of several classes of neutron-star-powered outflows: pulsar-wind nebulae (PWNe) inside shell supernova remnants (SNRs), PWNe interacting directly with interstellar medium (ISM), and magnetar-powered outflows. We describe radio, X-ray, and gamma-ray observations of PWNe, focusing first on integrated spectral-energy distributions (SEDs) and global spectral properties. High-resolution X-ray imaging of PWNe shows a bewildering array of morphologies, with jets, trails, and other structures. Several of the 23 so far identified magnetars show evidence for continuous or sporadic emission of material, sometimes associated with giant flares, and a few possible "magnetar-wind nebulae" have been recently identified.Comment: 61 pages, 44 figures (reduced in quality for size reasons). Published in Space Science Reviews, "Jets and Winds in Pulsar Wind Nebulae, Gamma-ray Bursts and Blazars: Physics of Extreme Energy Release

Sensitivity of the Cherenkov Telescope Array to spectral signatures of hadronic PeVatrons with application to Galactic Supernova Remnants

The local Cosmic Ray (CR) energy spectrum exhibits a spectral softening at energies around 3~PeV. Sources which are capable of accelerating hadrons to such energies are called hadronic PeVatrons. However, hadronic PeVatrons have not yet been firmly identified within the Galaxy. Several source classes, including Galactic Supernova Remnants (SNRs), have been proposed as PeVatron candidates. The potential to search for hadronic PeVatrons with the Cherenkov Telescope Array (CTA) is assessed. The focus is on the usage of very high energy $\gamma$-ray spectral signatures for the identification of PeVatrons. Assuming that SNRs can accelerate CRs up to knee energies, the number of Galactic SNRs which can be identified as PeVatrons with CTA is estimated within a model for the evolution of SNRs. Additionally, the potential of a follow-up observation strategy under moonlight conditions for PeVatron searches is investigated. Statistical methods for the identification of PeVatrons are introduced, and realistic Monte--Carlo simulations of the response of the CTA observatory to the emission spectra from hadronic PeVatrons are performed. Based on simulations of a simplified model for the evolution for SNRs, the detection of a $\gamma$-ray signal from in average 9 Galactic PeVatron SNRs is expected to result from the scan of the Galactic plane with CTA after 10 hours of exposure. CTA is also shown to have excellent potential to confirm these sources as PeVatrons in deep observations with $\mathcal{O}(100)$ hours of exposure per source.Comment: 34 pages, 16 figures, Accepted for publication in Astroparticle Physic