The granites of Galicia used as industrial rock

[Resumen] Se han estudiado todos los tipos de rocas graníticas de la Comunidad Autónoma de Galicia para su utilización como roca industrial: áridos y piedra natural. El mercado de los áridos y la industria de la Piedra Natural son dos subsectores mineros de primer orden, tanto en Galicia como en el resto de España, con producciones globales en granitoides de 10 Mt (millones de toneladas) y un valor anual cercano a los 31.000 Mpts (millones de pesetas) para Galicia. Los tipos litológicos beneficiados son: granitoides inhomogéneos, granitos de dos micas, granitos biot1ticos y ortogneises, cuyas diferencias petrológicas, texturales y mineralógicas van a condicionar su nivel de calidad en uno y otro mercado.[Abstract] We have studied aH the types of granitic rocks of the region of Galicia, for their use as an industrial rock in aggregates and natural stone. The aggregate market and the natural stone industry are very important mining subsection, as much in Galicia as in the rest of Spain, with general granite productions of 10 Mt (millions of tonnes) and 31.000 Mpts (miHions of pesetas) as the annual value in Galicia. The types of mining rocks are: inhomogeneous granite, two mica granite, biotite granite and granite gneiss, whose petrological, textural and mineralogical differences determine their quality level in both uses

Anti-DNA antibodies and circulating immune complexes (C1q-IgG) in recurrent aphtous stomatitis

Anti-DNA antibodies and circulating immune complexes (C1q-IgG) in sera from 50 patients with minor aphtae at the moment of study and 50 healthy controls, were determined. The obtained results were correlated with chronological and clinical parameters of the disease. Our findings show a greater number of patients than controls with higher values of anti-DNA antibodies. The time from the last active stage of the disease conditioned the anti-DNA antibody levels (p< 0.001). However, no significant differences among the number of recurrences in a year or the number of lesions in a ulcerative stage and the anti-DNA antibody concentrations were observed.Cette étude a pour but de déterminer les anticorps anti-ADN et les complexes immuns circulants C1q-IgG dans le sérum de 50 patients qui présentaient des aphtes mineurs au moment de l’étude et chez 50 contrôles. Les résultats obtenus sont en rapport avec les paramètres cliniques et chronologiques de la maladie. Nous avons trouvé des niveaux plus élevés d’anticorps anti-ADN chez les patients avec des aphtes mineurs, en comparaison avec les contrôles. Il existait une corrélation entre ces niveaux d’anticorps anti-ADN et le temps écoulé depuis le dernier épisode de la maladie (p<0.001). Il n’existait cependant pas de différences significatives entre les concentrations anti-ADN ni en ce qui concerne le nombre de récidives ni le nombre de lésions durant l’épisode

Non-local quantum effects in plasmons of graphene superlattices

By using a non-local, quantum mechanical response function we study graphene plasmons in a one-dimensional superlattice (SL) potential $V_0 \cos G_0x$. The SL introduces a quantum energy scale $E_G \sim \hbar v_F G_0$ associated to electronic sub-band transitions. At energies lower than $E_G$, the plasmon dispersion is highly anisotropic; plasmons propagate perpendicularly to the SL axis, but become damped by electronic transitions along the SL direction. These results question the validity of semiclassical approximations for describing low energy plasmons in periodic structures. At higher energies, the dispersion becomes isotropic and Drude-like with effective Drude weights related to the average of the absolute value of the local chemical potential. Full quantum mechanical treatment of the kinetic energy thus introduces non-local effects that delocalize the plasmons in the SL, making the system behave as a meta-material even near singular points where the charge density vanishes.Comment: 22 pages, 14 figure

Local versus Global Knowledge in the Barabasi-Albert scale-free network model

The scale-free model of Barabasi and Albert gave rise to a burst of activity in the field of complex networks. In this paper, we revisit one of the main assumptions of the model, the preferential attachment rule. We study a model in which the PA rule is applied to a neighborhood of newly created nodes and thus no global knowledge of the network is assumed. We numerically show that global properties of the BA model such as the connectivity distribution and the average shortest path length are quite robust when there is some degree of local knowledge. In contrast, other properties such as the clustering coefficient and degree-degree correlations differ and approach the values measured for real-world networks.Comment: Revtex format. Final version appeared in PR

Actividad ovina y diversificación de los modos de vida rurales en la alta montaña mexicana

UnpublishedTomo I . Sección: Sistemas Ganaderos-Economía y Gestión. Sesión: Sostenibilidad. Ponencia nº 3

Enhancing Transport Efficiency by Hybrid Routing Strategy

Traffic is essential for many dynamic processes on real networks, such as internet and urban traffic systems. The transport efficiency of the traffic system can be improved by taking full advantage of the resources in the system. In this paper, we propose a dual-strategy routing model for network traffic system, to realize the plenary utility of the whole network. The packets are delivered according to different "efficient routing strategies" [Yan, et al, Phys. Rev. E 73, 046108 (2006)]. We introduce the accumulate rate of packets, {\eta} to measure the performance of traffic system in the congested phase, and propose the so-called equivalent generation rate of packet to analyze the jamming processes. From analytical and numerical results, we find that, for suitable selection of strategies, the dual- strategy system performs better than the single-strategy system in a broad region of strategy mixing ratio. The analytical solution to the jamming processes is verified by estimating the number of jammed nodes, which coincides well with the result from simulation.Comment: 6 pages, 3 figure

An Emulator Toolbox to Approximate Radiative Transfer Models with Statistical Learning

Physically-based radiative transfer models (RTMs) help in understanding the processes occurring on the Earth’s surface and their interactions with vegetation and atmosphere. When it comes to studying vegetation properties, RTMs allows us to study light interception by plant canopies and are used in the retrieval of biophysical variables through model inversion. However, advanced RTMs can take a long computational time, which makes them unfeasible in many real applications. To overcome this problem, it has been proposed to substitute RTMs through so-called emulators. Emulators are statistical models that approximate the functioning of RTMs. Emulators are advantageous in real practice because of the computational efficiency and excellent accuracy and flexibility for extrapolation. We hereby present an “Emulator toolbox” that enables analysing multi-output machine learning regression algorithms (MO-MLRAs) on their ability to approximate an RTM. The toolbox is included in the free-access ARTMO’s MATLAB suite for parameter retrieval and model inversion and currently contains both linear and non-linear MO-MLRAs, namely partial least squares regression (PLSR), kernel ridge regression (KRR) and neural networks (NN). These MO-MLRAs have been evaluated on their precision and speed to approximate the soil vegetation atmosphere transfer model SCOPE (Soil Canopy Observation, Photochemistry and Energy balance). SCOPE generates, amongst others, sun-induced chlorophyll fluorescence as the output signal. KRR and NN were evaluated as capable of reconstructing fluorescence spectra with great precision. Relative errors fell below 0.5% when trained with 500 or more samples using cross-validation and principal component analysis to alleviate the underdetermination problem. Moreover, NN reconstructed fluorescence spectra about 50-times faster and KRR about 800-times faster than SCOPE. The Emulator toolbox is foreseen to open new opportunities in the use of advanced RTMs, in which both consistent physical assumptions and data-driven machine learning algorithms live together

Bounds for the time to failure of hierarchical systems of fracture

For years limited Monte Carlo simulations have led to the suspicion that the time to failure of hierarchically organized load-transfer models of fracture is non-zero for sets of infinite size. This fact could have a profound significance in engineering practice and also in geophysics. Here, we develop an exact algebraic iterative method to compute the successive time intervals for individual breaking in systems of height $n$ in terms of the information calculated in the previous height $n-1$. As a byproduct of this method, rigorous lower and higher bounds for the time to failure of very large systems are easily obtained. The asymptotic behavior of the resulting lower bound leads to the evidence that the above mentioned suspicion is actually true.Comment: Final version. To appear in Phys. Rev. E, Feb 199

Time dependence of breakdown in a global fiber-bundle model with continuous damage

A time-dependent global fiber-bundle model of fracture with continuous damage is formulated in terms of a set of coupled non-linear differential equations. A first integral of this set is analytically obtained. The time evolution of the system is studied by applying a discrete probabilistic method. Several results are discussed emphasizing their differences with the standard time-dependent model. The results obtained show that with this simple model a variety of experimental observations can be qualitatively reproduced.Comment: APS style, two columns, 4 figures. To appear in Phys. Rev.