5,868 research outputs found
Critical Exponents of the KPZ Equation via Multi-Surface Coding Numerical Simulations
We study the KPZ equation (in D = 2, 3 and 4 spatial dimensions) by using a
RSOS discretization of the surface. We measure the critical exponents very
precisely, and we show that the rational guess is not appropriate, and that 4D
is not the upper critical dimension. We are also able to determine very
precisely the exponent of the sub-leading scaling corrections, that turns out
to be close to 1 in all cases. We introduce and use a {\em multi-surface
coding} technique, that allow a gain of order 30 over usual numerical
simulations.Comment: 10 pages, 8 eps figures (2 figures added). Published versio
Phase-ordering of conserved vectorial systems with field-dependent mobility
The dynamics of phase-separation in conserved systems with an O(N) continuous
symmetry is investigated in the presence of an order parameter dependent
mobility M(\phi)=1-a \phi^2. The model is studied analytically in the framework
of the large-N approximation and by numerical simulations of the N=2, N=3 and
N=4 cases in d=2, for both critical and off-critical quenches. We show the
existence of a new universality class for a=1 characterized by a growth law of
the typical length L(t) ~ t^{1/z} with dynamical exponent z=6 as opposed to the
usual value z=4 which is recovered for a<1.Comment: RevTeX, 8 pages, 13 figures, to be published in Phys. Rev.
Crop diversity effects on soil organic matter and nitrate retention in surface and subsoils
Much of the available soil organic carbon (SOC) is in subsoil, yet few studies have evaluated how crop rotation affects SOC below the plow layer. This project looks at whether crop rotations with greater belowground C inputs would increase SOC stocks by delivering C to subsoil with relatively low SOC levels
Variables and distance covered during the World Cup Southafrica'10
El objetivo de este trabajo fue relacionar las variables contextuales y la velocidad media de los desplazamientos realizados por los equipos que participaron durante la Copa del Mundo Sudáfrica 2010. Se estudiaron 128 registros, medidos a través de la velocidad media en metros por minuto (m∙min1), durante los 64 partidos celebrados. Las variables contextuales fueron: tipo de competición, continente, resultado del partido, ranking FIFA del equipo y ranking FIFA del rival. Únicamente se han encontrado diferencias significativas en las variables continente (F=3,861;p=0,005) y resultado del partido en interacción con tipo de competición (F=3,999;p=0,029). Los resultados de este trabajo permiten aumentar el conocimiento referente a la influencia de las diferentes variables contextuales en la intensidad de desplazamiento de los equipos mientras disputan un partido de competición y, en consecuencia, gestionar la importancia de estos requerimientos energéticos con relación a la evaluación del rendimiento fÃsicoThe aim of this study was to determine whether there is any influence from different contextual variables on the physical performance of the teams during the South African World Cup 2010. The physical performances of 128 teams were studied, measured by distance travelled in meters per minute (m∙min-1), during the 64 matches played in South Africa 2010. The contextual variables were: type of competition, continent, match score, FIFA team ranking, and FIFA opponent ranking. Significant differences were found only in the continent variable (F=3.86,p=0.005) and match score in interaction with type of competition (F=3.999,p=0.029). The results of this study provide increasing knowledge concerning the influence of contextual variables on the physical demands on teams during a competition match and, therefore, will help to manage the importance of these energy requirements in relation to physical performanc
Un desafÃo a la pastoral y a la espiritualidad: el directorio sobre liturgia y piedad popular
The process of irreversible nucleation in multilayer growth. II. Exact results in one and two dimensions
We study irreversible dimer nucleation on top of terraces during epitaxial
growth in one and two dimensions, for all values of the step-edge barrier. The
problem is solved exactly by transforming it into a first passage problem for a
random walker in a higher-dimensional space. The spatial distribution of
nucleation events is shown to differ markedly from the mean-field estimate
except in the limit of very weak step-edge barriers. The nucleation rate is
computed exactly, including numerical prefactors.Comment: 22 pages, 10 figures. To appear in Phys. Rev.
Statistical physics of the Schelling model of segregation
We investigate the static and dynamic properties of a celebrated model of
social segregation, providing a complete explanation of the mechanisms leading
to segregation both in one- and two-dimensional systems. Standard statistical
physics methods shed light on the rich phenomenology of this simple model,
exhibiting static phase transitions typical of kinetic constrained models,
nontrivial coarsening like in driven-particle systems and percolation-related
phenomena.Comment: 4 pages, 3 figure
Routes to thermodynamic limit on scale-free networks
We show that there are two classes of finite size effects for dynamic models
taking place on a scale-free topology. Some models in finite networks show a
behavior that depends only on the system size N. Others present an additional
distinct dependence on the upper cutoff k_c of the degree distribution. Since
the infinite network limit can be obtained by allowing k_c to diverge with the
system size in an arbitrary way, this result implies that there are different
routes to the thermodynamic limit in scale-free networks. The contact process
(in its mean-field version) belongs to this second class and thus our results
clarify the recent discrepancy between theory and simulations with different
scaling of k_c reported in the literature.Comment: 5 pages, 3 figures, final versio
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