Estimación de tasas de erosión hídrica a partir de Dendrogeomorfología

La senda Schmid es un camino bien conocido dentro de la Sierra de Guadarrama, caracterizándose por presentar un uso recreativo casi exclusivo, generalmente asociado al senderismo. Como resultado, se ha producido un proceso acelerado de erosión hídrica que ha derivado en la exposición de raíces de Pinus sylvestris L. Investigaciones previas llevadas a cabo en esta área, han utilizado técnicas dendrogeomorfológicas para estimar tasas de erosión hídrica basadas en el análisis del cambio del patrón morfológico de las series de anillos de crecimiento. Para ello, se calculó el cociente definido por la profundidad de rebajamiento existente entre la parte superior de la raíz hasta la superficie actual del suelo; y el número de anillos que denotan exposición subaérea, al definir éstos un patrón de crecimiento excéntrico. En este trabajo se han reevaluado, a partir de 18 muestras tomadas a lo largo de la senda, tasas de erosión hídrica sobre la base de la determinación del primer año de exposición mediante el análisis anatómico. Para ello, en laboratorio se obtuvieron imágenes de láminas delgadas de madera de raíz, las cuales fueron adquiridas por medio de un dispositivo digital acoplado a un microscopio óptico. Los parámetros considerados fueron: a) anchura del anillo de crecimiento; b) número de células por anillo; c) porcentaje de madera tardía; y d) diámetro de la luz celular en la madera temprana. Una vez finalizado el estudio anatómico, y con el fin de validar las conclusiones preliminares derivadas de éste, se realizó un análisis ANOVA, verificándose diferencias que han permitido utilizar la fecha de exposición para reevaluar las tasas con una mayor precisión que por medio del simple cambio de patrón excéntrico. Los resultados de tasas de erosión acelerada obtenidos y sus tendencias evolutivas en el tiempo podrían ayudar a la gestión adecuada y regulación del tránsito de excursionistas en áreas de especial fragilidad

Сложность алгоритмов криптографической системы Эль–Гамаля и ихэффективность

Objective. - Electrical remodeling as well as atrial contractile dysfunction after the conversion of atrial fibrillation (AF) to sinus rhythm (SR) are mainly caused by a reduction of the inward L-type Ca2+ current (ICaL). We investigated whether the expression of L-type Ca2+-channel subunits was reduced in atrial myocardium of AF patients. Methods. - Right atrial appendages were obtained from patients undergoing coronary artery bypass graft surgery (CAD, n = 35) or mitral valve surgery (MVD, n = 37). Seventeen of the CAD patients and 18 of the MVD patients were in chronic (>3 months) AF, whereas the others were in SR. The protein expression of the L-type Ca2+-channel subunits {alpha}1C and {beta}2 was quantified by western blot analysis. Furthermore, we measured the density of dihydropyridine (DHP)-binding sites of the L-type Ca2+ channel using 3H-PN220-100 as radioligand. Results. - Surprisingly, the {alpha}1C and the {beta}2-subunit expression was not altered in atrial myocardium of AF patients. Also, the DHP-binding site density was unchanged. Conclusion. - The protein expression of the L-type Ca2+-channel subunits {alpha}1C or {beta}2 is not reduced in atrial myocardium of AF patients. Therefore, the reduced ICaL might be due to downregulation of other accessory subunits ({alpha}2{delta}), expression of aberrant subunits, changes in channel trafficking or alterations in channel function

Applying spatial reasoning to topographical data with a grounded geographical ontology

Grounding an ontology upon geographical data has been pro- posed as a method of handling the vagueness in the domain more effectively. In order to do this, we require methods of reasoning about the spatial relations between the regions within the data. This stage can be computationally expensive, as we require information on the location of points in relation to each other. This paper illustrates how using knowledge about regions allows us to reduce the computation required in an efficient and easy to understand manner. Further, we show how this system can be implemented in co-ordination with segmented data to reason abou

Thin accretion disc with a corona in a central magnetic field

We study the steady-state structure of an accretion disc with a corona surrounding a central, rotating, magnetized star. We assume that the magneto-rotational instability is the dominant mechanism of angular momentum transport inside the disc and is responsible for producing magnetic tubes above the disc. In our model, a fraction of the dissipated energy inside the disc is transported to the corona via these magnetic tubes. This energy exchange from the disc to the corona which depends on the disc physical properties is modified because of the magnetic interaction between the stellar magnetic field and the accretion disc. According to our fully analytical solutions for such a system, the existence of a corona not only increases the surface density but reduces the temperature of the accretion disc. Also, the presence of a corona enhances the ratio of gas pressure to the total pressure. Our solutions show that when the strength of the magnetic field of the central neutron star is large or the star is rotating fast enough, profiles of the physical variables of the disc significantly modify due to the existence of a corona.Comment: Accepted for publication in Astrophysics & Space Scienc

Loop effects and non-decoupling property of SUSY QCD in gb→tH−g b\to tH^{-}

One-loop SUSY QCD radiative correction to $gb \to tH^{-}$ cross section is calculated in the Minimal Supersymmetric Standard Model. We found that SUSY QCD is non-decoupling if the gluino mass and the parameter $\mu$, $A_t$ or $A_b$ are at the same order and get large. The non-decoupling contribution can be enhanced by large $\tan\beta$ and therefore large corrections to the hadronic production rates at the Tevatron and LHC are expected in the large $\tan\beta$ limit. The fundamental reason for such non-decoupling behavior is found to be some couplings in the loops being proportional to SUSY mass parameters.Comment: 15 pages, 5 PS figures. A proof of non-decouplings of SUSY-QCD, Comments on corresponding QCD correction and references adde