1,578 research outputs found
Variables cinéticas de la batida relacionadas con el rendimiento del salto horizontal a pies juntos
El presente trabajo analiza las variables fuerza-tiempo (f-t), velocidad-tiempo (V-t) y potenciatiempo
(P-t) que más se relacionan con la distancia del salto horizontal (SH), y discute sobre la
validez de este test como predictor de la fuerza explosiva de las extremidades inferiores. Participaron
144 estudiantes de educación física (96 hombres y 48 mujeres) que realizaron 3 saltos verticales
(SV) sobre plataforma de contacto y 3 SH sobre plataforma de fuerzas. Se obtuvieron correlaciones
significativas (p<0.05) entre SH y f-t, SH y P-t (relativas al peso corporal) y SH y V-t. Paralelamente,
se obtuvieron diferencias significativas (p<0.05) en estas variables entre hombres y mujeres
(6-36%). También se obtuvieron altas relaciones (p<0.001) entre SH y SV en hombres y mujeres (r=
0.68 y r= 0.69, respectivamente). En conclusión, el test de SH es válido para evaluar la fuerza
explosiva de las extremidades inferiores. Algunos aspectos metodológicos deben tenerse en cuenta
para analizar y tratar las variables cinéticas del SH. Futuros trabajos deben seleccionar las variables
cinéticas más importantes para corregir la técnica del SH.The present work analyzes the force-time (f-t), speed-time (V-t) and power-time (P-t) variables
related with the standing long jump distance (SLJ). Also, this work analyzes the validity of the SLJ
in order to predict the lower extremities explosive force. 144 physical education students (96 men
and 48 women) participated in this study. The students carried out 3 vertical jumps (VJ) on contact
mat, and 3 SLJ on force plate. We have obtained significant correlations (p<0.05) between SLJ and
f-t, SLJ and P-t (relative to body weight) and SLJ and V-t variables. Significant differences (p<0.05)
between men and women were obtained in these variables (6-36 %). Also, relationships between
SLJ and VJ (p< 0.001) were obtained in men and women (r= 0.68 and r= 0.69, respectively). In
conclusion, the SLJ test is valid in order to evaluate the lower extremities explosive force. Some
methodological aspects are important in order to analyze the SLJ kinetic variables. Future works
should select the most important SLJ kinetic variables in order to correct the SLJ technique
Integral Field Spectroscopy based H\alpha\ sizes of local Luminous and Ultraluminous Infrared Galaxies. A Direct Comparison with high-z Massive Star Forming Galaxies
Aims. We study the analogy between local U/LIRGs and high-z massive SFGs by
comparing basic H{\alpha} structural characteristics, such as size, and
luminosity (and SFR) surface density, in an homogeneous way (i.e. same tracer
and size definition, similar physical scales). Methods. We use Integral Field
Spectroscopy based H{\alpha} emission maps for a representative sample of 54
local U/LIRGs (66 galaxies). From this initial sample we select 26 objects with
H{\alpha} luminosities (L(H{\alpha})) similar to those of massive (i.e. M\ast
\sim 10^10 M\odot or larger) SFGs at z \sim 2, and observed on similar physical
scales. Results. The sizes of the H{\alpha} emitting region in the sample of
local U/LIRGs span a large range, with r1/2(H{\alpha}) from 0.2 to 7 kpc.
However, about 2/3 of local U/LIRGs with Lir > 10^11.4 L\odot have compact
H{\alpha} emission (i.e. r1/2 < 2 kpc). The comparison sample of local U/LIRGs
also shows a higher fraction (59%) of objects with compact H{\alpha} emission
than the high-z sample (25%). This gives further support to the idea that for
this luminosity range the size of the star forming region is a distinctive
factor between local and distant galaxies of similar SF rates. However, when
using H{\alpha} as a tracer for both local and high-z samples, the differences
are smaller than the ones recently reported using a variety of other tracers.
Despite of the higher fraction of galaxies with compact H{\alpha} emission, a
sizable group (\sim 1/3) of local U/LIRGs are large (i.e. r1/2 > 2 kpc). These
are systems showing pre-coalescence merger activity and they are
indistinguishable from the massive high-z SFGs galaxies in terms of their
H{\alpha} sizes, and luminosity and SFR surface densities.Comment: Accepted for publication in A&A. (!5 pages, 7 figures, 2 tables
Dark matter direct detection of a fermionic singlet at one loop
Abstract The strong direct detection limits could be pointing to dark matter – nucleus scattering at loop level. We study in detail the prototype example of an electroweak singlet (Dirac or Majorana) dark matter fermion coupled to an extended dark sector, which is composed of a new fermion and a new scalar. Given the strong limits on colored particles from direct and indirect searches we assume that the fields of the new dark sector are color singlets. We outline the possible simplified models, including the well-motivated cases in which the extra scalar or fermion is a Standard Model particle, as well as the possible connection to neutrino masses. We compute the contributions to direct detection from the photon, the Z and the Higgs penguins for arbitrary quantum numbers of the dark sector. Furthermore, we derive compact expressions in certain limits, i.e., when all new particles are heavier than the dark matter mass and when the fermion running in the loop is light, like a Standard Model lepton. We study in detail the predicted direct detection rate and how current and future direct detection limits constrain the model parameters. In case dark matter couples directly to Standard Model leptons we find an interesting interplay between lepton flavor violation, direct detection and the observed relic abundance
Análisis de las adaptaciones inducidas por cuatro semanas de entrenamiento pliométrico
La suplementación con creatina en el deporte y su relación con el rendimiento deportivo
Linear programming of a slate quarry
[Abstract] A new exploitation of roofing slate has several possibilities of marketing
depending on the sizes of the pieces that it makes. Three sizes has been chosen
among aH the possibilities in base of the conditions and the production of the
rock in the quarry, the marketing limitation and the final price of the producto
We've procces aH these data to obtain the optimun output, with the simplex
algorithm. The objective function (week invoicing) and the restrictions of the
problem are created in canonical and standard formo Optimun solution has been
obtained among aH the basic and practical ones, using the graphic and the
analytic method. Sorne conclusions come from the algorithm matrix about the
outputs for each marketing option
Propagación del desgarro de tejido biológico empleado en la construcción de bioprótesis cardíacas en función de la forma y el tipo de sutura
En este trabajo hemos estudiado la fuerza necesaria para propagar un desgarro en un tejido de pericardio de avestruz, tejido alternativo y en estudio para la fabricación de bioprótesis cardiacas. Se analiza la influencia de dos de las suturas más empleadas en cirugía cardiovascular: Prolene® y Gore-Tex®, en este comportamiento mecánico. El tejido se suturó de dos formas distintas borde-borde y en solapa. Para los ensayos se utilizó un péndulo Elmendorf capaz de medir, la fuerza necesaria para propagar el desgarro de un tejido.
Se analizaron 106 ensayos, tras aplicar criterios de selección morfológica habituales en estos ensayos y que homogenizaron las muestras por su espesor y las hicieron comparables.
La serie de control, no suturada, necesitó 24 N, como valor medio, para propagar el desgarro en 1 cm, mientras que las series suturadas borde con borde, con Gore-Tex® y con Prolene®, necesitaron, para la misma propagación del d-esga-rro, 12.69 N (p=0.001) y 16.18 N respectivamente. Esta pérdida de resistencia no se observó en las series suturadas con solape de 1 cm de longitud, 29.73 N, como valor medio, en la serie suturada con Gore-Tex® y 42.56 N, como valor medio, en la serie suturada con Prolene® (p=0.000). La sutura de Prolene® mostró una mayor resistencia a la propagación del desgarro que la sutura de Gore-Tex®.
Una sutura protegida, mediante una zona previa no rasgada, dificulta la propagación del desgarro y puede tener interés desde un punto de vista constructivo en el diseño de las formas de sutura de implantes o bioprótesis
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