5,337 research outputs found
The relative dependence of Spanish landscape pattern on environmental and geographical variables over time
The analysis of the dependence of landscape patterns on environment was carried out in order to investigate the landscape structure evolution of Spain. The underlying concept was that the dependence between landscape spatial structure and environmental factors could be gradually decreasing over time. Land cover data were recorded from aerial photo interpretation of 206 4 x 4 km(2) samples from three different years: 1956, 1984 and 1998. Geographical variables were taken into consideration together with the purely environmental ones. General Linear Models of repeated measures were then used to segregate environmental from geographical effects on the pattern of the land cover patches of the samples. Aridity, lithology and topography were the environmental factors used to analyse structural indices of landscape. Landscape composition has a higher dependence on environment than configuration. Environmental variables showed higher correlations with landscape composition and configuration than geographical variables. Ail-long them, overall the climatic aridity and topography significantly accounted for more variation than did lithology. There was a high degree of stability in land cover composition over time, with some significant exceptions. Nevertheless, the registered increase of fragmentation over time has demonstrated that configuration measures are needed to fully assess landscape change
Can the dehesa system work as a carbon sink? Analysis of the case of the Dehesón del Encinar.
Agroforestry systems are considered multi-purpose systems, aimed towards achieving an increased and more efficient use of natural resources. This acquires greater relevance in Mediterranean areas where high yield is compromised and non-timber goods and services are the main ecosystems products. The dehesa is a well-known agroforestry system that occupies more than 3.10 6 ha in the Iberian Peninsula. In spite of their importance, there is a lack of knowledge of multiple issues regarding the ecosystem functioning and dynamics. One of the potential services of the dehesa is CO2 fixation which should be incorporated into the management planning. In this work the potential of dehesas as C sink is analysed in the framework of a Spanish Research National Plan project carried out in several dehesa system locations in Spain
Gross output and livestock sales modelling in Spanish extensive farms using PLSR
The aim of this paper is to model some production variables in extensive livestock farms located in the dehesa ecosystem. We intend to use not only purely economic variables in the construction of the model, but also structural variables in order to identify the characteristics of the farms that have the higher influence. Another objective is to be able to predict these variables at the farm level, using structural variables that are easy to measure. The data used in this work were obtained from a questionnaire survey to the holders/managers of a sample of 69 dehesa farms in Extremadura (SW Spain). The statistical methodology used for the construction of the model was Partial Least Square Regression (PLSR). It can be concluded that the variables relative to farm intensification, to labour and especially to Iberian pig breeding, are those that take part mainly in the model.dehesa, livestock farming systems, partial least square regression, gross output, Crop Production/Industries, Livestock Production/Industries, Research Methods/ Statistical Methods,
Complexity analysis of Klein-Gordon single-particle systems
The Fisher-Shannon complexity is used to quantitatively estimate the
contribution of relativistic effects to on the internal disorder of
Klein-Gordon single-particle Coulomb systems which is manifest in the rich
variety of three-dimensional geometries of its corresponding quantum-mechanical
probability density. It is observed that, contrary to the non-relativistic
case, the Fisher-Shannon complexity of these relativistic systems does depend
on the potential strength (nuclear charge). This is numerically illustrated for
pionic atoms. Moreover, its variation with the quantum numbers (n, l, m) is
analysed in various ground and excited states. It is found that the
relativistic effects enhance when n and/or l are decreasing.Comment: 4 pages, 3 figures, Accepted in EPL (Europhysics Letters
Configuration Complexities of Hydrogenic Atoms
The Fisher-Shannon and Cramer-Rao information measures, and the LMC-like or
shape complexity (i.e., the disequilibrium times the Shannon entropic power) of
hydrogenic stationary states are investigated in both position and momentum
spaces. First, it is shown that not only the Fisher information and the
variance (then, the Cramer-Rao measure) but also the disequilibrium associated
to the quantum-mechanical probability density can be explicitly expressed in
terms of the three quantum numbers (n, l, m) of the corresponding state.
Second, the three composite measures mentioned above are analytically,
numerically and physically discussed for both ground and excited states. It is
observed, in particular, that these configuration complexities do not depend on
the nuclear charge Z. Moreover, the Fisher-Shannon measure is shown to
quadratically depend on the principal quantum number n. Finally, sharp upper
bounds to the Fisher-Shannon measure and the shape complexity of a general
hydrogenic orbital are given in terms of the quantum numbers.Comment: 22 pages, 7 figures, accepted i
Shannon Entropy as Characterization Tool in Acoustics
We introduce Shannon's information entropy to characterize the avoided
crossing appearing in the resonant Zener-like phenomenon in ultrasonic
superlattices made of two different fluidlike meta- materials. We show that
Shannon's entropy gives a correct physical insight of the localization effects
taking place and manifest the informational exchange of the involved acoustic
states in the narrow region of parameters where the avoided crossing occurs.
Results for ultrasonic structures consisting of alternating layers of
methyl-metacrylate and water cavities, in which the acoustic Zener effect were
recently demonstrated, are also reported.Comment: 4 pages, 5 figures. Submitted to Phys. Rev. Let
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