Quantum dynamics of a spin-1/2 charged particle in the presence of magnetic field with scalar and vector couplings

The quantum dynamics of a spin-1/2 charged particle in the presence of magnetic field is analyzed for the general case where scalar and vector couplings are considered. The energy spectra are explicitly computed for different physical situations, as well as their dependencies on the magnetic field strength, spin projection parameter and vector and scalar coupling constants.Comment: arXiv admin note: text overlap with arXiv:1403.411

On the 2D Dirac oscillator in the presence of vector and scalar potentials in the cosmic string spacetime in the context of spin and pseudospin symmetries

The Dirac equation with both scalar and vector couplings describing the dynamics of a two-dimensional Dirac oscillator in the cosmic string spacetime is considered. We derive the Dirac-Pauli equation and solve it in the limit of the spin and the pseudo-spin symmetries. We analyze the presence of cylindrical symmetric scalar potentials which allows us to provide analytic solutions for the resultant field equation. By using an appropriate ansatz, we find that the radial equation is a biconfluent Heun-like differential equation. The solution of this equation provides us with more than one expression for the energy eigenvalues of the oscillator. We investigate these energies and find that there is a quantum condition between them. We study this condition in detail and find that it requires the fixation of one of the physical parameters involved in the problem. Expressions for the energy of the oscillator are obtained for some values of the quantum number $n$. Some particular cases which lead to known physical systems are also addressed.Comment: 15 pages, 8 figures, matches published versio

Bound states of bosons and fermions in a mixed vector-scalar coupling with unequal shapes for the potentials

The Klein-Gordon and the Dirac equations with vector and scalar potentials are investigated under a more general condition, $V_{v}+V_{s}= \mathrm{constant}$. These intrinsically relativistic and isospectral problems are solved in a case of squared hyperbolic potential functions and bound states for either particles or antiparticles are found. The eigenvalues and eigenfuntions are discussed in some detail and the effective Compton wavelength is revealed to be an important physical quantity. It is revealed that a boson is better localized than a fermion when they have the same mass and are subjected to the same potentials.Comment: 3 figure

Balance de líquidos y electrolitos en cirugía

Al introducir el tema general del cuidado pre y post-operatorio con relación a los estudios sobre el balance de líquidos y electrolitos, volumen sanguíneo y estado de nutrición de los enfermos en general, parece apropiado traer a cuento una anotación de los Dres. Lockwood y Randall del "Presbyterian Hospital of New York": "El cirujano está en la obligación de dominar en la terapéutica quirúrgica las aplicaciones prácticas de los métodos fundamentales de la bioquímica y de la fisiología. El cirujano que delega su responsabilidad en el cuidado pre y post-operatorio de los enfermos a su cuidado, está en grave peligro de no ser más que un técnico y no merece un sitio en la cirugía científica de hoy en día"

Managing in Latin America: Common issues and a research agenda

Latin America is a paradoxical region. It has unique conditions that make it one of the most attractive contexts worldwide for doing business, but it also faces serious challenges that severely underscore these opportunities. We apply a simple framework of analysis to describe the Latin American business environment and detect research opportunities. For that, we focus on four aspects of the region: (1) the institutional context, (2) the macroeconomic environment, (3) the consumer profile, and (4) the natural resource endowments. We summarize firms' strategic choices that result from this context and analyze their consequences for new business creation, incumbents' survival and growth, and sources of competitive advantages. We conclude by outlining a management research agenda.Fil: Vassolo, Roberto Santiago. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Austral; ArgentinaFil: De Castro, Julio O.. IE University; EspañaFil: Gomez Mejia, Luis R.. Texas A&M University; Estados Unido

Light-activated electroforming in ITO/ZnO/p-Si resistive switching devices

We report on light-activated electroforming of ZnO/p-Si heterojunction memristors with transparent indium tin oxide as the top electrode. Light-generated electron-hole pairs in the p-type substrate are separated by the external electric field and electrons are injected into the active ZnO layer. The additional application of voltage pulses allows achieving different resistance states that end up in the realization of the low resistance state (LRS). This process requires much less voltage compared to dark conditions, thus avoiding undesired current overshoots and achieving a self-compliant device. The transport mechanisms governing each resistance state are studied and discussed. An evolution from an electrode-limited to a space charge-limited transport is observed along the electroforming process before reaching the LRS, which is ascribed to the progressive formation of conductive paths that consequently induce the growth of conductive nanofilaments through the ZnO layer. This work was financially supported by the Spanish Ministry of Economy and Competitiveness (Project Nos. TEC2012-38540-C02-01 and TEC2016-76849-C2-1-R). O.B. also acknowledges the subprogram "Ayudas para Contratos Predoctorales para la Formación de-Doctores" from the Spanish Ministry of Economy and Competitiveness for economical support. J.L.F. acknowledges the subprogram "Ayudas para la Formación de Profesorado Universitario" (No. FPU16/06257) from the Spanish Ministry of Education, Culture and Sports for economical support. X.P., C.L., and C.G. are grateful to C. Frilay for his expertise in the maintenance of the sputtering setup used for the growth of the ZnO films