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Anatomía de la dispersión urbana en Barcelona
Mu?iz,Iván; García-López,Miquel-Angel;
EURE (Santiago) , 2013, DOI: 10.4067/S0250-71612013000100008
Abstract: there is no commonly accepted definition of urban sprawl, and therefore applied research has worked with different indicators aiming to grasp the diverse meanings assigned to the term. this study measures how the dispersion of population and employment in the barcelona metropolitan region (bmr) developed between 1986 and 2001. the dimensions that were investigated are divided into two groups. the first one involves dimensions of urban form (decentralization, low density and discontinuity), and the second, of urban structure. as opposed to some studies, where polycentrism and linear growth are presented as two forms of sprawl, in our case we contrast the idea of structured urban expansion (linear or poly-centric) with de structured urban expansion (amorphous, chaotic or random), identifying the latter with the fourth dimension of sprawl. the results suggest that population and employment in the bmr has become decentralized in a non-concentrated way and, in the case of population, the density has decreased. however, the bmr has not grown in a discontinuous or de-structured way, but quite the contrary.
Anatomía de la dispersión urbana en Barcelona
Iván Mu?iz,Miquel-Angel García-López
EURE (Santiago) , 2013,
Abstract: No existe una definición comúnmente aceptada de dispersión urbana (urban sprawl), de modo que la investigación aplicada ha trabajado con diferentes indicadores que pretenden a su vez capturar los distintos significados con que se ha dotado al término. En este trabajo se mide cómo ha evolucionado la dispersión de la población y del empleo de la Región Metropolitana de Barcelona (RMB) entre 1986 y 2001. Las dimensiones exploradas se dividen en dos grupos: i) forma urbana (desconcentración, baja densidad y discontinuidad) y ii) estructura urbana. A diferencia de algunos trabajos donde el policentrismo y el crecimiento lineal se presentan como dos formas de dispersión, en nuestro caso contraponemos la idea de expansión urbana estructurada (lineal o policéntrica) con la de expansión urbana desestructurada (amorfa, caótica o aleatoria), equiparando esta última con la cuarta dimensión de la dispersión. Los resultados obtenidos indican que la población y el empleo de la RMB se han descentralizado de forma desconcentrada y la densidad residencial se ha reducido. Sin embargo, la RMB no ha crecido de forma discontinua ni desestructurada, sino todo lo contrario. There is no commonly accepted definition of urban sprawl, and therefore applied research has worked with different indicators aiming to grasp the diverse meanings assigned to the term. This study measures how the dispersion of population and employment in the Barcelona Metropolitan Region (BMR) developed between 1986 and 2001. The dimensions that were investigated are divided into two groups. The first one involves dimensions of urban form (decentralization, low density and discontinuity), and the second, of urban structure. As opposed to some studies, where polycentrism and linear growth are presented as two forms of sprawl, in our case we contrast the idea of structured urban expansion (linear or poly-centric) with de structured urban expansion (amorphous, chaotic or random), identifying the latter with the fourth dimension of sprawl. The results suggest that population and employment in the BMR has become decentralized in a non-concentrated way and, in the case of population, the density has decreased. However, the BMR has not grown in a discontinuous or de-structured way, but quite the contrary.
A short proof of the odd-girth theorem
Edwin R. van Dam,Miquel Angel Fiol
Mathematics , 2012,
Abstract: Recently, it has been shown that a connected graph $\Gamma$ with $d+1$ distinct eigenvalues and odd-girth $2d+1$ is distance-regular. The proof of this result was based on the spectral excess theorem. In this note we present an alternative and more direct proof which does not rely on the spectral excess theorem, but on a known characterization of distance-regular graphs in terms of the predistance polynomial of degree $d$.
The Laplacian spectral excess theorem for distance-regular graphs
Edwin R. van Dam,Miquel Angel Fiol
Mathematics , 2014, DOI: 10.1016/j.laa.2014.06.001
Abstract: The spectral excess theorem states that, in a regular graph G, the average excess, which is the mean of the numbers of vertices at maximum distance from a vertex, is bounded above by the spectral excess (a number that is computed by using the adjacency spectrum of G), and G is distance-regular if and only if equality holds. In this note we prove the corresponding result by using the Laplacian spectrum without requiring regularity of G.
On perturbations of almost distance-regular graphs
Cristina Dalfó,Edwin R. van Dam,Miquel Angel Fiol
Mathematics , 2012, DOI: 10.1016/j.laa.2011.05.004
Abstract: In this paper we show that certain almost distance-regular graphs, the so-called $h$-punctually walk-regular graphs, can be characterized through the cospectrality of their perturbed graphs. A graph $G$ with diameter $D$ is called $h$-punctually walk-regular, for a given $h\le D$, if the number of paths of length $\ell$ between a pair of vertices $u,v$ at distance $h$ depends only on $\ell$. The graph perturbations considered here are deleting a vertex, adding a loop, adding a pendant edge, adding/removing an edge, amalgamating vertices, and adding a bridging vertex. We show that for walk-regular graphs some of these operations are equivalent, in the sense that one perturbation produces cospectral graphs if and only if the others do. Our study is based on the theory of graph perturbations developed by Cvetkovi\'c, Godsil, McKay, Rowlinson, Schwenk, and others. As a consequence, some new characterizations of distance-regular graphs are obtained.
Viabilidad de un programa de prevención selectiva de los problemas de ansiedad en la infancia aplicado en la escuela
Miquel Tortella Feliu,Mateu Servera,María Balle,Miquel Angel Fullana
International Journal of Clinical and Health Psychology , 2004,
Abstract: Los programas de prevención de los trastornos psicopatológicos en la infancia y la adolescencia son todavía muy escasos. El objetivo del presente estudio fue el de analizar mediante un experimento complejo (dise o 2x3 de un factor entre grupo con dos niveles y un factor intra tiempo- con tres niveles), la viabilidad de un programa breve de prevención selectiva de los problemas de ansiedad aplicado en la escuela en una muestra de ni os y ni as de Educación Secundaria Obligatoria. Trece ni os/-as con elevada sensibilidad a la ansiedad recibieron un programa para la prevención de la ansiedad. La sensibilidad a la ansiedad en la infancia y adolescencia se considera como uno de los principales factores de riesgo para el desarrollo de trastornos de ansiedad. Un grupo de sujetos procedentes de la misma muestra y con puntuaciones normales en todas las variables estudiadas sirvió de grupo control. Al final de la intervención, el grupo al que se aplicó el programa preventivo mostró reducciones estadísticamente significativas respecto al grupo control en dos de las tres variables de resultado analizadas: sensibilidad a la ansiedad, ansiedad rasgo pero no en sintomatología depresiva. Los resultados se mantenían en el seguimiento a tres meses.
Di-μ-chlorido-bis{chlorido[(R)/(S)-1,5-diphenyl-3-(2-pyridyl-κN)-2-pyrazoline-κN2]zinc(II)}
Miquel Barceló-Oliver,Angel Terrón,Angel García-Raso,Iztok Turel
Acta Crystallographica Section E , 2010, DOI: 10.1107/s1600536810026127
Abstract: In the centrosymmetric binuclear title compound, [Zn2Cl4(C20H17N3)2], the coordination geometry of the ZnII ion can be described as a distorted ZnN2Cl3 trigonal bipyramid (τ = 0.89), arising from the N,N′-bidentate ligand, a terminal chloride ion and two bridging chloride ions. The N atoms occupy one axial and one equatorial site and the terminal chloride ion occupies an equatorial site. The dihedral angle between the pyridine and pyrazole rings is 12.8 (2)°. In the crystal, aromatic π–π stacking [centroid–centroid separations = 3.812 (3) and 3.848 (3) ] and C—H...Cl and C—H...π interactions help to establish the packing.
Estudo do metabolismo energético muscular em atletas por 31P-ERM
Santos, Maria Gisele dos;González de Suso, Jose Manuel;Moreno, Angel;Cabanas, Miquel;Arus, Carles;
Revista da Associa??o Médica Brasileira , 2004, DOI: 10.1590/S0104-42302004000200026
Abstract: background: the aim of this study was to characterize the muscular reservoirs of phosphorilated energetic components of athletes using 31p-mrs. methods: the sample was formed by 14 elite athletes from the center for high sportive performance (car, sant cugat del vallés, spain). the pattern of the phosphorilated metabolites was measured from the muscle vastus medialis by 31p-mrs. oral supplementation of 20 g of creatine monohydrate was given during 14 days. two groups of athletes were formed according to their physical characteristics (weight, height, body mass index, maximum o2 uptake). the first group received a placebo (maltodextrine), while the second group received a diet of creatine supplement. the exercise was performed inside the resonance tunnel with a frequency of 60 rpm with both legs. results: the results showed that significant decrease occurred in phosphocreatine (pcr), inorganic phosphate (pi) and intracellular ph after supplementation. conclusion: it was concluded that the exercise performed by the long distance runners recruited in this study, detected by 31p-mrs, reduced the consumption of pcr during exercise owing to creatine supplementation diet.
Assessment of Dressed Time-Dependent Density-Functional Theory for the Low-Lying Valence States of 28 Organic Chromophores
Miquel Huix-Rotllant,Andrei Ipatov,Angel Rubio,Mark E. Casida
Physics , 2010, DOI: 10.1016/j.chemphys.2011.03.019
Abstract: Almost all time-dependent density-functional theory (TDDFT) calculations of excited states make use of the adiabatic approximation, which implies a frequency-independent exchange-correlation kernel that limits applications to one-hole/one-particle states. To remedy this problem, Maitra et al.[J.Chem.Phys. 120, 5932 (2004)] proposed dressed TDDFT (D-TDDFT), which includes explicit two-hole/two-particle states by adding a frequency-dependent term to adiabatic TDDFT. This paper offers the first extensive test of D-TDDFT, and its ability to represent excitation energies in a general fashion. We present D-TDDFT excited states for 28 chromophores and compare them with the benchmark results of Schreiber et al.[J.Chem.Phys. 128, 134110 (2008).] We find the choice of functional used for the A-TDDFT step to be critical for positioning the 1h1p states with respect to the 2h2p states. We observe that D-TDDFT without HF exchange increases the error in excitations already underestimated by A-TDDFT. This problem is largely remedied by implementation of D- TDDFT including Hartree-Fock exchange.
Dual concepts of almost distance-regularity and the spectral excess theorem
Cristina Dalfó,Edwin R. van Dam,Miquel Angel Fiol,Ernest Garriga
Mathematics , 2012, DOI: 10.1016/j.disc.2012.03.003
Abstract: Generally speaking, `almost distance-regular' graphs share some, but not necessarily all, of the regularity properties that characterize distance-regular graphs. In this paper we propose two new dual concepts of almost distance-regularity, thus giving a better understanding of the properties of distance-regular graphs. More precisely, we characterize $m$-partially distance-regular graphs and $j$-punctually eigenspace distance-regular graphs by using their spectra. Our results can also be seen as a generalization of the so-called spectral excess theorem for distance-regular graphs, and they lead to a dual version of it.
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