oalib

Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99

Submit

Any time

2020 ( 26 )

2019 ( 238 )

2018 ( 282 )

2017 ( 296 )

Custom range...

Search Results: 1 - 10 of 226836 matches for " Sanchez R. "
All listed articles are free for downloading (OA Articles)
Page 1 /226836
Display every page Item
The sequence of origin of the postmetamorphic rays in Heliaster and Labidiaster (Echinodermata: Asteroidea)
SANCHEZ R,PATRICIO;
Revista chilena de historia natural , 2000, DOI: 10.4067/S0716-078X2000000400002
Abstract: postmetamorphic rays in heliaster and labidiaster originate in four `quadrants' between the five primary rays, and not normally in the madreporic interradius. the rays originate in one of two very definite sequences depending on the species. h. kubiniji and h. multiradiatus share one sequence, whereas h. canopus, h. helianthus and labidiaster share the other sequence. pycnopodia, rathbunaster, heliaster and labidiaster add rays at far greater sizes and in a manner that is distinctive from other multiradiate starfish, possibly indicating a new taxonomic unit
The sequence of origin of the postmetamorphic rays in Heliaster and Labidiaster (Echinodermata: Asteroidea) Origen sequencial de los rayos postmetamorficos en Heliaster y Labidiaster (Echinodermata: Asteroidea)
PATRICIO SANCHEZ R
Revista chilena de historia natural , 2000,
Abstract: Postmetamorphic rays in Heliaster and Labidiaster originate in four `quadrants' between the five primary rays, and not normally in the madreporic interradius. The rays originate in one of two very definite sequences depending on the species. H. kubiniji and H. multiradiatus share one sequence, whereas H. canopus, H. helianthus and Labidiaster share the other sequence. Pycnopodia, Rathbunaster, Heliaster and Labidiaster add rays at far greater sizes and in a manner that is distinctive from other multiradiate starfish, possibly indicating a new taxonomic unit Los rayos post-metamórficos en Heliaster y Labidiaster se originan en cuatro"cuadrantes" entre los cinco rayos primarios, y no como ocurre normalmente en el interradio del madreporito. Los rayos se originan en una de dos secuencias definidas, dependiendo de la especie. H. kubiniji y H. multiradiatus comparten una secuencia, mientras que H. canopus, H. helianthus y Labidiaster comparten otra secuancia. Pycnopodia, Rathbunaster, Heliaster y Labidiaster adicional rayos de tama os mucho mayores y de una manera que es distintiva de aquel de otras estrellas de mar multiradiadas, posiblemente indicando su pertenencia a una nueva unidad taxonómica
Third Quantization in Bergmann-Wagoner Theory
Mora C.,Sanchez R.
Progress in Physics , 2008,
Abstract: We present the third quantization of Bergmann-Wagoner scalar-tensor and Brans Dicke solvable toy models. In the first one we used an exponential cosmological term, for the second one we considered vanishing cosmological constant. In both cases, it is found that the number of the universes produced from nothing is very large.
Scaling properties of planetary calderas and terrestrial volcanic eruptions
L. Sanchez,R. Shcherbakov
Nonlinear Processes in Geophysics (NPG) , 2012, DOI: 10.5194/npg-19-585-2012
Abstract: Volcanism plays an important role in transporting internal heat of planetary bodies to their surface. Therefore, volcanoes are a manifestation of the planet's past and present internal dynamics. Volcanic eruptions as well as caldera forming processes are the direct manifestation of complex interactions between the rising magma and the surrounding host rock in the crust of terrestrial planetary bodies. Attempts have been made to compare volcanic landforms throughout the solar system. Different stochastic models have been proposed to describe the temporal sequences of eruptions on individual or groups of volcanoes. However, comprehensive understanding of the physical mechanisms responsible for volcano formation and eruption and more specifically caldera formation remains elusive. In this work, we propose a scaling law to quantify the distribution of caldera sizes on Earth, Mars, Venus, and Io, as well as the distribution of calderas on Earth depending on their surrounding crustal properties. We also apply the same scaling analysis to the distribution of interevent times between eruptions for volcanoes that have the largest eruptive history as well as groups of volcanoes on Earth. We find that when rescaled with their respective sample averages, the distributions considered show a similar functional form. This result implies that similar processes are responsible for caldera formation throughout the solar system and for different crustal settings on Earth. This result emphasizes the importance of comparative planetology to understand planetary volcanism. Similarly, the processes responsible for volcanic eruptions are independent of the type of volcanism or geographical location.
Roughness Scaling of Deconstruction Interfaces
Juan R. Sanchez
Physics , 2002,
Abstract: The scaling properties of one-dimensional deconstructed surfaces are studied by numerical simulations of a disaggregation model. The model presented here for the disaggregation process takes into account the possibility of having quenched disorder in the bulk under deconstruction. The disorder can be considered to model several types of irregularities appearing in real materials (dislocations, impurities). The presence of irregularities makes the intensity of the attack to be not uniform. In order to include this effect, the computational bulk is considered to be composed by two types of particles. Those particles which can be easily detached and other particles that are not sensible to the etching attack. As the detachment of particles proceeds in time, the dynamical properties of the rough interface are studied. The resulting one-dimensional surface show self-affine properties and the values of the scaling exponents are reported when the interface is still moving near the depinning transition. According to the scaling exponents presented here, the model must be considered to belong to a new universality class.
Structure and Dynamics of Surface Adsorbed Clusters
J. R. Sanchez
Physics , 1999,
Abstract: Extensive numerical simulation are reported for the structure and dynamics of large clusters on metal(100) surfaces. Different types of perimeter hopping processes makes center-of-mass of the cluster to follow a a random walk trajectory. Then, a {\it diffusion coefficient} $D$ can be defined as $\lim\limits_{t\to \infty} D(t)$, with $D(t)=< d^2 >/(4t)$ and $d$ the displacement of the center-of-mass. In the simulations, the dependence of the diffusion coefficient on those perimeter hopping processes can be analyzed in detail, since the relations between different rates for the processes are explicitly considered as parameters.
Surface Properties of a Selective Dissagregation Model
Juan R. Sanchez
Physics , 1999,
Abstract: There are three fundamental physical processes that gives rise to the morphology of a surface: deposition, surface diffusion and desorption. The characteristics of the interfaces generated by the combination of deposition and surface diffusion has been well studied during the past decades . In particular for growth models, particles are added to the surface and then are allowed to relax by different mechanisms. Many of this models have been shown to lead to the formation of self-affine surfaces, characterized by scaling exponents. From a theoretical point of view, the studies dedicated to the self-affine interfaces generated by growth models can be considered to follow two main branches. The studies about the properties of discrete models and the studies about continuous models. The first ones where dedicated mainly to the study of the properties of computational models in which the growth proceeds on an initially empty lattice representing a d-dimensional substrate. At each time step, the height of the lattice sites is increased by units (usually one unit) representing the incoming particles. Different models only differs on the relaxation mechanisms proposed to capture specific experimental characteristics. Then, the models are classified according to the values of the scaling exponents in several universality classes.
A modified one-dimensional Sznajd model
Juan R. Sanchez
Physics , 2004,
Abstract: The Sznajd model is an Ising spin model representing a simple mechanism of making up decisions in a closed community. In the model each member of the community can take two attitudes A or B represented by a spin up or spin down state respectively. It has been shown that, in one-dimension starting from a totally random initial state, three final fixed points can be obtained; all spins up, all spins down or an antiferromagnetic state in which each site take a state which is opposite from its two nearest neighbors. Here, a modification of the updating rule of the Sznajd model is proposed in order to avoid such antiferromagnetic state since it is considered to be an unrealistic state in a real community.
Quantum Ferroelectric Magnets in Underdoped Manganites
E. R. Sanchez Guajardo
Physics , 2006,
Abstract: Using the degenerate double exchange Hamiltonian with on-site Coulomb interactions we show that there is an instability towards the displacement of the manganese ion in La_{1-x}Ca_{x}MnO_{3}. The result is a dipole moment due to the charge disproportionation and the lattice distortions that gives rise to the predicted magnetic ferroelectric phase for dopings in between x=4 and x=5. The instability is stabilized by the phonons of the lattice, resulting in a stable configuration of the degrees of freedom of the system.
Order of Degrees of Freedom in Underdoped Manganites
E. R. Sanchez Guajardo
Physics , 2006,
Abstract: Using the degenerate double exchange Hamiltonian with on-site Coulomb interactions we show how the spin, charge, and orbital state degrees of freedom vary in La_{1-x}Ca_{x}MnO_{3} for dopings in between x=4 and x=5. With the ordered configuration of the system we investigate the band structure for different values of the doping.
Page 1 /226836
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.