Gerardo Jorge Vazquez

Optical transition in self-assembled InAs/GaAs quantum lens under high hydrostatic pressure

We present a simulation to characterize the dependence on hydrostatic pressure for the photoluminescence spectra in self-assembled quantum dots with lens shape geometry. We have tested the physical effects of the band offset and electron-hole effective masses on the optical emission in dot lens. The model could be implemented to get qualitative information of the parameters involved in the quantum dot or the measured optical properties as function of pressure.

Induced Cultural Globalization by an External Vector Field in an Enhanced Axelrod Model

A new model is proposed, in the context of Axelrod’s model for the study of cultural dissemination, to include and external vector field (VF) which describes the effects of mass media on social systems. The VF acts over the whole system and it is characterized by two parameters: a non-null overlap with each agent in the society and a confidence value of its information. Beyond a threshold value of the confidence there is induced monocultural globalization of the system lined up with the VF. Below this value, the multicultural states are unstable and certain homogenization of the system is obtained in opposite line up according to that we have called negative publicity effect. Three regimes of behavior for the spread process of the VF information as a function of time are reported.

Induced Monoculture In Axelrod Model With Clever Mass Media

A new model is proposed, in the context of Axelrods model for the study of cultural dissemination, to include an external vector field (VF) which describes the effects of mass media on social systems. The VF acts over the whole system and it is characterized by two parameters: a nonnull overlap with each agent in the society and a confidence value of its information. Beyond a threshold value of the confidence, there is induced monocultural globalization of the system lined up with the VF. Below this value, the multicultural states are unstable and certain homogenization of the system is obtained in opposite line up according to that we have called negative publicity effect. Three regimes of behavior for the spread process of the VF information as a function of time are reported.

Effects of geometry, applied hydrostatic pressure and magnetic field on the electron-hole transition energy in a GaAs-Ga 1-x Al x As pillbox immersed in a system of Ga 1-y Al y As

In this work, we study the behavior of the electron-hole transition energy in a GaAs-Ga1-xAlxAs pillbox immersed in a system of Ga1-yAlyAs as a function of thickness of the ladder barrier potential for a fixed length of the pillbox, length of the pillbox, thickness of the ladder barriers and pillbox position in the host of Ga1-yAlyAs. The behavior of the electron-hole transition energy as a function of an applied hydrostatic pressure and an applied magnetic field is also studied. For both electron and hole we found that in the strong confinement regime (L≤10A) energy of the ground state as function of the position of the pillbox relative to the ladder barrier potential presents a behavior similar to the binding energy of a hydrogenic impurity in quantum wells, quantum wires and quantum dots [L. Esaki, R. Tsu, IBM J. Res. Dev. 14 (1970) 61; G. Bastard, Phys. Rev. B 24 (1981) 4714; N. Porras-Montenegro, J. Lopez-Gondar, L.E. Oliveira, Phys. Rev. B 43 (1991) 1824]. Electron-heavy hole transition energies increase with the applied magnetic field. Also, we have found that these transition energies, as a function of the applied hydrostatic pressure, present an excellent agreement with experimental reports by Venkateswaran et al. [phys. Rev. B 33 (1986) 8416].

SOCIAL HIERARCHIES WITH AN ATTRACTIVE SITE DISTRIBUTION

We reinvestigate the model of Bonabeau et al.1 of self-organizing social hierarchies by including a distribution of attractive sites. Agents move randomly except in the case where an attractive site is located in its neighborhood. We find that the transition between an egalitarian society at low population density and a hierarchical one at high population density strongly depends on the distribution and percolation of the valuable sites. We also show how agent diffusivity is closely related to social hierarchy.

STARK EFFECT IN A FINITE REGION FOR A 1D COULOMB POTENTIAL

We calculate the states of a one-dimensional hydrogen atom under the effect of an electric field (Stark effect) in the strong field regime being the field confined in a finite region of width 2a (capacitor region). We find numerically the solution inside the capacitor and match it to an analytical solution outside the capacitor. Although the electric field tends to separate the two opposite charges particles, the total energy of the system decreases with increasing electric field strength. Our results are useful as a guideline to study strong electric field effects in electronic states of impurities or excitons in 1D systems.