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

Searching for Trans Ethyl Methyl Ether in Orion KL

We report on the tentative detection of $trans$ Ethyl Methyl Ether (tEME), $t-CH_3CH_2OCH_3$, through the identification of a large number of rotational lines from each one of the spin states of the molecule towards Orion KL. We also search for $gauche$-$trans$-n-propanol, $Gt-n-CH_3CH_2CH_2OH$, an isomer of tEME in the same source. We have identified lines of both species in the IRAM 30m line survey and in the ALMA Science Verification data. We have obtained ALMA maps to establish the spatial distribution of these species. Whereas tEME mainly arises from the compact ridge component of Orion, Gt-n-propanol appears at the emission peak of ethanol (south hot core). The derived column densities of these species at the location of their emission peaks are $\leq(4.0\pm0.8)\times10^{15} cm^{-2}$ and $\leq(1.0\pm0.2)\times10^{15} cm^{-2}$ for tEME and Gt-n-propanol, respectively. The rotational temperature is $\sim100 K$ for both molecules. We also provide maps of $CH_3OCOH$, $CH_3CH_2OCOH$, $CH_3OCH_3$, $CH_3OH$, and $CH_3CH_2OH$ to compare the distribution of these organic saturated O-bearing species containing methyl and ethyl groups in this region. Abundance ratios of related species and upper limits to the abundances of non-detected ethers are provided. We derive an abundance ratio $N(CH_3OCH_3)/N(tEME)\geq150$ in the compact ridge of Orion.Comment: Accepted in A&A Letter

Electronic and magnetic properties of Fe clusters inside finite zigzag single-wall carbon nanotubes

Density functional calculations of the electronic structure of the Fe12 cluster encapsulated inside finite singlewall zigzag carbon nanotubes of indices (11,0) and (10,0) have been performed. Several Fe12 isomers have been considered, including elongated shape isomers aimed to fit well inside the nanotubes, and the icosahedral minimum energy structure. We analyze the structural and magnetic properties of the combined systems, and how those properties change compared to the isolated systems. A strong ferromagnetic coupling between the Fe atoms occurs both for the free and the encapsulated Fe12 clusters, but there is a small reduction (3–7.4μB) of the spin magnetic moment of the encapsulated clusters with respect to that of the free ones (μ = 38μB). The reduction of the magnetic moment is mostly due to the internal redistribution of the spin charges in the iron cluster. In contrast, the spin magnetic moment of the carbon nanotubes, which is zero for the empty tubes, becomes nonzero (1–3μB) because of the interaction with the encapsulated cluster. We have also studied the encapsulation of atomic Fe and the growth of small Fen clusters (n = 2, 4, 8) encapsulated in a short (10,0) tube. The results suggest that the growth of nanowires formed by distorted tetrahedral Fe4 units will be favorable in (10,0) nanotubes and nanotubes of similar diameter

Psychometric Properties of the Barrier Autoinform for the Practice of the Physical Exercise (ABPEF)

El estudio consistió en examinar las propiedades psicométricas del cuestionario de autoinforme de barreras para la práctica del ejercicio físico (ABPEF) y comprobar el efecto del género sobre dichas barreras. Se han estudiado sus propiedades psicométricas con una muestra de 342 adolescentes (media de edad: 15.02±1.86). Se realizaron análisis de confiabilidad, análisis factorial exploratorio, correlación ítem con puntaje total y análisis factorial confirmatorio. Se encuentra una buena confiabilidad interna (α = .86), adecuada correlación ítem con puntaje total, y la presencia de cuatro factores en el análisis factorial exploratorio con correlaciones significativas entre las mismas. El análisis factorial confirmatorio mostró adecuado ajuste a los datos de un modelo tetrafactorial del cuestionario (χ2 /gl = 3.696; GFI=.89; AGFI=.86; RMSEA=.061). El género femenino presenta mayores barreras para la práctica del ejercicio físico. Este cuestionario es un instrumento fiable y válido y se sugiere su uso en futuras investigacionesThe objective of this study was to examine the psychometric properties of the self-report questionnaire for physical exercise (ABPEF). And to chek the effect of gender on those barriers. Their psychometric properties were studied with a sample of 342 adolescents (mean age: 15.02 ± 1.86). We performed reliability analysis, exploratory factor analysis, item correlation with total score and confirmatory factor analysis. We found a good internal reliability (α = .86), an adequate item correlation with total score, and the presence of four factors in the exploratory factor analysis with significant correlations between them. The confirmatory factor analysis showed adequate adjustment to the data of a tetrafactorial model of the questionnaire (χ2 / gl = 3.696; GFI = .89; AGFI = .86; RMSEA = .061). The female gender presents greater barriers to the practice of physical exercise. This questionnaire is a reliable and valid instrument for the population under study, and its use in future research is suggeste

Appearance of pyrophyllite as replacements of spiriferids (Brachiopoda) Shells of the devonian in the Central-Iberian zone (Hesperic Massif, Spain).

[Abstract] Amacroscopic pyrophyllite bearing mineralization related to shells ofspiriferids has beeen found in the Herrera Formation (southern Central-Iberian Zone, Hesperic Massif, Spain). The observed mineral asociation is pyrophyllite + nacrite + quartz + calcite + anhydrite, and it is interpreted as resulting from the substitution ofinitial carbonatic shell by a Si, Al, S rich hydrothermal solutio

Half-metallic finite zigzag single-walled carbon nanotubes from first principles

10 pages, 15 figures.-- PACS nrs.: 73.22.-f, 75.75.+a, 72.80.Rj, 85.75.-d.Density-functional calculations predict half-metallicity in zigzag single-walled carbon nanotubes of finite length with the two ends saturated with hydrogen. We have analyzed the change of the α- and β-spin electronic gaps under the influence of an electric field applied along the nanotube axis. The half-metallic behavior, in which the electronic gap is zero for one spin flavor and nonzero for the other, is obtained for a critical electric field of 3.0/w V/Å, where w is the length of the nanotube. This critical field is the same as that predicted for graphene nanoribbons. By a detailed analysis of the spin structure of the ground state, we show the relevance of the edge states, electronic states spatially localized at the carbon atoms of the nanotube boundaries, on the on-set of half-metallicity, and on the magnetic properties of the finite semiconducting zigzag nanotubes.Research supported by MEC of Spain (Projects No. MAT2005-06544-C03-01, No. MAT2005-06544-C03-03, No. FIS2004-06490-C03-00, and MONACEM), by Junta de Castilla y León (Project No. VA039A05), by Basque Government (Project No. IE05-151) under the ETORTEK Program (NANOMAT), and by the European Network of Excellence NANOQUANTA (Grant No. NM4-CT-2004-500198).Peer reviewe