Cambios en la física del suelo e incrementos de la escorrentía y la erosión tras un incendio forestal

[Resumen] Los cambios en las propiedades físicas del suelo después de un incendio forestal, determinan una menor capacidad de infiltración y son responsables del incremento de escorrentía y erosión. El siguiente artículo analiza la textura, la porosidad y la estabilidad estructural del suelo de un bosque quemado en 1993. Se analizan también las diferencias que las intensidades del fuego pudieron tener en estas propiedades. Estos aspectos son comparados entre una parcela control de bosque y tres áreas afectadas por diferentes intensidades del incendio. Se han obtenido tasas de escorrentía hasta 8 veces superiores en la zona de intensidad alta, y tasas de erosión 30 veces superiores en episodios concretos de precipitación. La suma de los efectos producidos en la física del suelo, así como la desprotección del mismo por parte de la vegetación explicarían el aumento de la escorrentía y la erosión.[Abstract] Runoff and erosion increment after forest fires are, in part, a consequence of changes in the physical properties of the soil. This paper analizes the texture, porosity and aggregate stability of the soil of a forest burnt in 1993. The differences of these properties as a consequence of different fire intensities are also analized. As a consequence of these changes the soil has less infiltration capacity, and there is an increment of runoff and erosiono These two aspects are compared between a control plot in the forest, and in three areas afected with different fire intensity. Runoff increases 8 times and erosion 30 times in the high fire intensity area during concret rainfal1 events. The effects of fire in the physical properties plus the burnt of vegetation explain the increases of runoff and erosion

The highly ionized disk wind of GRO J1655-40

Aims: The galactic superluminal microquasar GRO J1655-40 started a new outburst in February 2005, after seven years in quiescence, rising to a high/soft state in March 2005. In this paper we study the X-ray spectra during this rise. Methods: We observed GRO J1655-40 with XMM-Newton, on 27 February 2005, in the low/hard state, and on three consecutive days in March 2005, during the rise of the source to its high/soft state. The EPIC-pn camera was used in the fast-read Burst mode to avoid photon pile-up. Results: First, we contributed to the improvement of the calibration of the EPIC-pn, since the high flux received from the source required some refinements in the correction of the Charge Transfer Efficiency of the camera.Second, we find that the X-ray spectrum of GRO J1655-40 is dominated in the high/soft state by the thermal emission from the accretion disk, with an inner radius of 13-14(D/3.2kpc)km and a maximum temperature of 1.3 keV. Two absorption lines are detected in the EPIC-pn spectra, at 6.7-6.8 and 7.8-8.0 keV, which can be identified either as blended Fe XXV and Fe XXVI K-alpha and K-beta lines, or as blueshifted Fe XXV. We find no orbital dependence on the X-ray properties, which provides an upper limit for the inclination of the system of 73 degr. The RGS spectrometers reveal interstellar absorption features at 17.2AA, 17.5AA (Fe L edges) and 23.54AA (OI K-alpha). Finally, while checking the interstellar origin of the OI line, we find a general correlation of the OI K-alpha line equivalent width with the hydrogen column density using several sources available in the literature.Comment: 10 pages, 7 figures, 4 tables. Revised version with important change

Military spending and economic growth in China: a regime-switching analysis

This article has been made available through the Brunel Open Access Publishing Fund.This article investigates the impact of military spending changes on economic growth in China over the period 1953 to 2010. Using two-state Markov-switching specifications, the results suggest that the relationship between military spending changes and economic growth is state dependent. Specifically, the results show that military spending changes affect the economic growth negatively during a slower growth-higher variance state, while positively within a faster growth-lower variance one. It is also demonstrated that military spending changes contain information about the growth transition probabilities. As a policy tool, the results indicate that increases in military spending can be detrimental to growth during slower growth-higher growth volatility periods. © 2014 © 2014 The Author(s). Published by Taylor & Francis

Insulin degradation by adipose tissue is increased in human obesity

White adipose tissue samples from obese and lean patients were used for the estimation ofinsulin protease and insulin:glutathione transhydrogenase using 1251-labeled insulin. There was no activity detected in the absence of reduced glutathione, which indicates that insulin is cleaved in human adipose "tissue through reduction of the disulfide bridge between the chains. O bese patients showed higher transhydrogenase activity (per U tissue protein wt, per U tissue wt, and in the total adipose tissue mass) than the lean group. There is a significant correlation between the activity per U tissue wt, and protein and total activity in the whole adipose tissue with respect to body mass index, with a higher activity in obese patients. The potential ofinsulin cleavage by adipose tissue in obese patients was a mean 5.6-fold higher than that in controla. The coexistence of high insulinemia and high cleavage capability implies that insulin secretion and turnover are increased in the o bese. Thus, white adipose tissue may be crucial in the control of energy availability through modulation ofinsulin cleavage

Acoustic properties of colloidal crystals

We present a systematic study of the frequency band structure of acoustic waves in crystals consisting of nonoverlapping solid spheres in a fluid. We consider colloidal crystals consisting of polystyrene spheres in water, and an opal consisting of close-packed silica spheres in air. The opal exhibits an omnidirectional frequency gap of considerable width; the colloidal crystals do not. The physical origin of the bands are discussed for each case in some detail. We present also results on the transmittance of finite slabs of the above crystals.Comment: 7 pages, 9 figures, prb approve