Results 1 - 10 of 52
Results 1 - 10 of 52. Search took: 0.016 seconds
|Sort by: date | relevance|
[en] LAI is a key factor in light and rainfall interception processes in forest stands and, for this reason, is called to play an important role in global change adaptive silviculture. Therefore, it is necessary to develop practical and operative methodologies to measure this parameter as well as simple relationships with other silviculture variables. This work has studied 1) the feasibility of LAI-2000 sensor in estimating LAI-stand when readings are taken under direct sunlight conditions; and 2) the ability of LAI in studying rainfall partitioned into throughfall (T) in an Aleppo pine stand after different thinning intensities, as well as its relationships to basal area, (G), cover (FCC), and tree density (D). Results showed that the angular correction scheme applied to LAI-2000 direct-sunlight readings stabilized them for different solar angles, allowing a better operational use of LAI-2000 in Mediterranean areas, where uniform overcast conditions are difficult to meet and predict. Forest cover showed the highest predictive ability of LAI (R2 = 0.98; S = 0.28), then G (R2 = 0.96; S = 0.43) and D (R2 = 0.50; S = 0.28). In the hydrological plane, T increased with thinning intensity, being G the most explanatory variable (R2 = 0.81; S = 3.07) and LAI the one that showed the poorest relation with it (R2 = 0.69; S = 3.95). These results open a way for forest hydrologic modeling taking LAI as an input variable either estimated form LAI-2000 or deducted from inventory data. (Author) 36 refs.
[en] The aim of this paper was to analyze the segregation of some polymorphisms in three genes (CAPN1, CAST and DGAT1) related to meat quality in the Lidia cattle breed and some of its main lineages. To that effect, 119 individuals from the Lidia breed were analyzed. Although the association between the polymorphisms and the phenotype has never been demonstrated in this breed, the absence of fixed genotypes for these polymorphisms in the studied population makes the Lidia cattle a good candidate to develop selection objectives. The clear differentiation among lineages for most of the genes studied reinforces the high reproductive isolation presented in the Lidia cattle as revealed by previous studies on the structure of the population within the Lidia breed using microsatellite markers. Considering both issues in the design of breeding schemes will be necessary to save the lineages and not to lose this valuable genetic resource. Finally, it would be necessary to carry out an in depth search for new polymorphisms in genes associated with meat quality and to perform needed association analyses between the SNPs segregating in Lidia cattle and traits of economic interest.
[en] The use of antibiotics to treat mastitis and other infectious diseases in dairy sheep and goats is a widespread practice nowadays that can, when not properly applied, result in the contamination of the milk supply. Spanish legislation establishes the control of the presence of antibiotic residues in sheep and goat’s milk using screening methods that detect, at least, beta-lactam drugs. Microbial inhibitor tests using Geobacillus stearothermophilus var. calidolactis and specific receptor-binding assays are most widely employed for this purpose. The detection rates of screening tests routinely used in Spain have been calculated considering the frequency of use of veterinary drugs commonly applied in ovine and caprine livestock to treat and prevent mastitis as well as the test sensitivity toward these substances at safety levels. In general, the use of a single test allows detecting 62.8-82.4% of the antibiotics employed. For sheep milk, the total detection range achieved with microbial tests was significantly higher than that reached with rapid receptor tests. However, no significant differences between the two types of methods were found when goat's milk was analysed. In both types of milk, the simultaneous use of two screening tests with a different analytical basis increases the total detection range significantly, reaching values ≥ 90% in some cases (81.5-90.1% for sheep and 84.7-92.6% for goats). However, the periodical use of screening tests able to detect quinolones, macrolides or aminoglycosides would be recommended to carry out more efficient screening and ensure the safety of milk and dairy products from sheep and goats. (Author)
[en] The double-beta-decay process are studied in order to test the existence of an electronic lepton number conservation law. General formulae for the transitions )+→)+, )+→2+, )+→4+ are given for neutrinoless double beta-decay. The double beta-decay of 48Ca is studied in detail. From the experimental data it is concluded that absolute value delta-1(<=)3.10-6
[en] The value of the electrochemical technique Reverse Pulse Voltammetry (RPV) for the characterization of chemical equilibria in solution is theoretically investigated. For this, the RPV response of the square scheme is studied at spherical and disc electrodes of any size assuming that the chemical reactions are at equilibrium. When the effective diffusion coefficients of the oxidized and reduced species are the same, analytical solutions are reported for both electrode geometries. Otherwise, a rigorous analytical solution is derived for spherical electrodes whereas the case of microdiscs is addressed by numerical simulations. The theory for the square scheme enables the study of the RPV response in very different situations, including the cases where the electrochemical and/or chemical transformations alter significantly the species diffusivity such as in electron transfer processes in room temperature ionic liquids or in the association of the electroactive species with (bio) macromolecules and nanoparticles. It is found that, when medium-size (disc or spherical) microelectrodes are employed, the RPV method enables the simultaneous determination of the effective diffusion coefficients of the oxidized and reduced species as well as the apparent formal potential. These magnitudes make it possible a sound physicochemical characterization of the system
[en] Highlights: • Ni_2P catalyst is much more active than CoP one for Cl-removal. • Benzene is the main reaction product for Ni_2P catalyst. • The activity followed the order ClB > 1,4-DClB ≈ 1,2,4-TClB > 1,3-DClB > 1,2-DClB for Ni_2P. • The activity followed the order ClB > 1,4-DClB > 1,3-DClB > 1,2-DClB > 2,4-TClB for CoP. • Active phase dispersion, P-concentration on the surface and H-species on the surface explain the results. - Abstract: Ni_2P and CoP catalysts (5 wt.% of metal) supported on a commercial SiO_2 were tested in the gas phase catalytic hydrodechlorination (HDCl) of mono (chlorobenzene-ClB) and polychlorobenzenes (PCBs) (1,2- dichlorobenzene (1,2-DClB), 1,3-dichlorobenzene (1,3-DClB), 1,4-dichlorobenzene (1,4-DClB), and 1,2,4-trichlorobenzene (1,2,4-TClB)) at atmospheric pressure. It was investigated how the number and position of chlorine atoms in the molecule influence the HDCl activity. The prepared catalysts were characterized by X-ray diffraction (XRD), CO chemisorption, N_2 adsorption–desorption at −196 °C, and X-ray photoelectron spectroscopy (XPS). Characterization results indicated better active phase dispersion and greater amount of P on the Ni_2P catalyst surface. Catalytic results showed that the Ni_2P was more active and stable in this type of reactions. The hydrodechlorination activity decreased by increasing the number of chlorine atoms in the molecule and chlorine substituents in close proximity. The observed trend in the HDCl activity was: ClB > 1,4-DClB > 1,3-DClB > 1,2-DClB > 1,2,4-TClB. The exception was the catalytic response after 24 h on stream observed for the Ni_2P in the HDCl reaction of 1,2,4-TClB, which was equal to that observed for the 1,4-DClB molecule, and also yielding benzene as the main reaction product
[en] The quantization of a priori hamiltonian predictive systems is studied. It is applied to quantize the family of N-particle relativistic models. The relativistic two-particle oscillator is studied in detail and finally our results are compared with others that already appeared in the literature
[en] The degradation of permanent frozen ground (permafrost) and the increase in the thickness of the active layer may be caused both by natural processes (such as global climate change) and by anthropic activity, which changes the natural environmental conditions that allow its existence, as has been widely reported to occur in the northern polar and subpolar regions. In the case of Antarctica, some scientific research stations are located in areas with permafrost, such as the Spanish Antarctic station “Gabriel de Castilla” on Deception Island. In the place where the station is located, an important increase in erosion has been observed in recent years, including the excavation of new gullies and the erosion of the coastal cliffs. In order to develop an initial analysis of the possible effects of the station on the permafrost degradation, ground temperature has been monitored since 2012 and the thickness and of the active layer and the temperature, both inside and beneath the station, have also been sporadically measured. Here we show the results and discuss how the station reduces the freezing of the ground during the winter when the station is closed and facilitates the warming of the ground during the living periods of the station in the Antarctic summer. Those initial results and conclusions make necessary to continue the study of the permafrost and the active layer in the station site by systematic monitoring of the ground temperature and the thickness of the active layer.
[es]La degradación de los suelos congelados (permafrost) y el aumento de espesor de la capa activa pueden deberse tanto a factores naturales, como antrópicos (edificaciones, carreteras, cimentaciones, etc.) que modifican las condiciones naturales y, por tanto, sus características termo-mecánicas, tal y como ha sido profusamente estudiado en el hemisferio Norte. En el caso de la Antártida, algunas bases se encuentran en zonas de permafrost, como es el caso de la base española Gabriel de Castilla en la isla Decepción. En la zona donde se localiza esta base se ha observado un importante aumento de la erosión, con la excavación de torrenteras y el retroceso del escarpe costero. Con la hipótesis de la degradación del permafrost como causa principal, se decidió evaluar los posibles efectos de la base (su módulo principal) en el estado de la capa activa y el permafrost sobre el que se asienta. Para ello, entre 2012 y 2015 se han tomado distintas medidas de temperatura del suelo, espesor de la capa activa y de temperatura en el interior del edificio y bajo la base, cuyos resultados se presentan y analizan en este trabajo. Se concluye que la edificación ejerce un doble efecto, reduciendo el enfriamiento del terreno durante el invierno, en el que permanece cerrada, y facilitando su calentamiento durante los meses de actividad, durante el verano antártico. Estos resultados hacen que sea necesario un estudio de las causas y se tomen las medidas y acciones necesarias para reducir los efectos de la degradación de la capa activa bajo la base, así como una investigación sistemática del estado de la capa activa y el permafrost en la zona afectada por la presencia de la base antártica.
[en] High resolution observations of the H2-6367.7 A quadrupole line and rotationally resolved features of the NH3-6450 A and CH4-6815 A bands at the centre of the Jovian disk are presented. An interpretation of the results in terms of an inhomogeneous atmospheric radiative transfer model has been made. This model has also been applied to low resolution measurements of the CH4-6190 A band and NH3-6450 A band, already published, obtained also in September, 1985. A range of cloud parameters are shown to be compatible with the observations. The effects of the variations of the model parameters on the continuum reflectivity are also discussed
[en] In the present work, we aimed to present an alternative methodology to the use of commercial devices for daily quality assurance of the linac energy in the clinic using the electronic portal-imaging device combined with a pair of cylindrical aluminum pieces.Methodology: With an external degradation of beam energy, we achieved a modification of around 2% (considered as clini-cally relevant) in the representative energy parameter (PDD20,10: ratio of dose percentage at 20 and 10 cm depths, respectively). The proposed methodology was then validated for the detection of this beam perturbation.Results: We observed that the methodology was able to distinguish the intentioned deviations performed in photon energy with a good reproducibility, obtaining threshold-warning levels.Conclusions: The new methodology allows to establish a warning in case of a deviation clinically relevant in beam energy quality with the only use of the portal-imaging system together with a couple of aluminium pieces. The system has demonstrated to be reliable as well as easy to implement without needing extra equipment.
[es]Objetivo: Presentar una metodología para el control diario de la calidad energética del haz en rutina clínica, alternativa al uso de sistemas comerciales, empleando el sistema de imagen portal en combinación con un par de piezas cilíndricas de aluminio.Método: Degradando externamente el haz de fotones, se consiguió una desviación en el parámetro representativo de la energía (PDD20,10: cociente de porcentaje de dosis a las profundidades de 20 y 10 cm, respectivamente) de en torno al 2%, considerada como clínicamente relevante. La metodología propuesta se validó para la detección de esta perturbación del haz. Resultados: Se observó que, de manera reproducible, el método era capaz de distinguir las desviaciones efectuadas en la energía del haz, y se establecieron unos valores umbral de alarma. Conclusiones: La metodología propuesta permite detectar desviaciones clínicamente relevantes de la energía, mediante el uso del sistema de imagen portal y dos piezas cilíndricas de aluminio. El sistema ha demostrado ser fiable y sencillo de implementar, sin requerir equipamiento adicional.