Evanescent states in quantum wires with Rashba spin-orbit coupling

We discuss the calculation of evanescent states in quasi-one-dimensional quantum wires in the presence of Rashba spin-orbit interaction. We suggest a computational algorithm devised for cases in which longitudinal and transverse motions are coupled. The dispersion relations are given for some selected cases, illustrating the feasibility of the proposed computational method. As a practical application, we discuss the solutions for a wire containing a potential step.Comment: 8 pages, 8 figure

Transport through Majorana nanowires attached to normal leads

This paper presents a coupled channel model for transport in 2D semiconductor Majorana nanowires coupled to normal leads. When the nanowire hosts a zero mode, conspicuous signatures on the linear conductance are predicted. An effective model in second quantization allowing a fully analytical solution is used to clarify the physics. We also discuss the nonlinear current response ($dI/dV$)Comment: 17 pages, 6 figure

Multichannel effects in Rashba quantum wires

We investigate intersubband mixing effects in multichannel quantum wires in the presence of Rashba spin-orbit coupling and attached to two terminals. When the contacts are ferromagnetic and their magnetization direction is perpendicular to the Rashba field, the spin-transistor current is expected to depend in a oscillatory way on the Rashba coupling strength due to spin coherent oscillations of the travelling electrons. Nevertheless, we find that the presence of many propagating modes strongly influences the spin precession effect, leading to (i) a quenching of the oscillations and (ii) strongly irregular curves for high values of the Rashba coupling. We also observe that in the case of leads' magnetization parallel to the Rashba field, the conductance departs from a uniform value as the Rashba strength increases. We also discuss the Rashba interaction induced current polarization effects when the contacts are not magnetic and investigate how this mechanism is affected by the presence of several propagating channels.Comment: 8 pages, 7 figure

Localized magnetic states in Rashba dots

We study the formation of local moments in quantum dots arising in quasi-one dimensional electron wires due to localized spin-orbit (Rashba) interaction. Using an Anderson-like model to describe the occurrence of the magnetic moments in these Rashba dots, we calculate the local magnetization within the mean-field approximation. We find that the magnetization becomes a nontrivial function of the Rashba coupling strength. We discuss both the equilibrium and nonequilibrium cases. Interestingly, we obtain a magnetic phase which is stable at large bias due to the Rashba interaction.Comment: 8 pages, 4 figures; to appear in Phys. Rev.

Relationship between attitudes towards physical activity and sports and academic performance of spanish and portuguese college students

The propose of this study is to analyse the existing relationship between attitudes towards physical activity and sports and academic performance at university level from a cross-cultural perspective. This study is based on two samples of Spanish and Portuguese college students from the Degree in Tourism. The sample of Spanish students comprises 108 students, while the sample of Portuguese students comprises 92 students. Psychometric analysis through latent structure analysis is conducted. For this, the Dosil's (2002) scale of attitudes towards physical activity and sports was used. The results show a direct relationship between attitudes towards physical activity and academic performance, yet only in the sample of Spanish male students. Moreover, it was confirmed the validation of scale of attitudes towards physical activity and sports

Tributacion sobre el Patrimonio de las Personas Naturales en Chile : Impuesto sobre Herencias y Donaciones, Impuestos Territorial y Patentes Municipales

62 p.La importancia de definir Impuesto sobre el Patrimonio en Chile es notable, ya que se ha intentado precaver su existencia en un sistema que prefiere gravar la renta y el consumo, más que la riqueza personal. Así, existen impuestos que gravan el patrimonio de los individuos, como lo son el impuesto sobre Herencias y Donaciones, el impuesto territorial o contribución y las patentes municipales. Dichas manifestaciones de imposición patrimonial, crea en la mayoría de los casos fenómenos no deseados, como la doble tributación, por ejemplo en el impuesto sobre las herencias, cuando el causante que ya pago renta, lo paga, y luego de la muerte de la cónyuge que la recibió, se grava su patrimonio, respecto de sus hijos, quienes pagarían dos veces dicho tributo. Así, esta memoria intenta ser una denuncia de este tipo de imposición económicamente innecesaria y poco acorde con el Chile moderno, en vías de desarrollo

Magnetic-field instability of Majorana modes in multiband quantum wires

We investigate the occurrence of Majorana modes in semiconductor quantum wires in close proximity with a superconductor and when both, Rashba interaction and magnetic field, are present. We consider long, but finite, multiband wires (namely, planar wires with dimensions $L_x\gg L_y$). Our results demonstrate that interband mixing coming from Rashba spin orbit term hybridizes Majorana pairs originating from different transverse modes while simultaneously closing the effective gap. Consequently, multiple Majorana modes do not coexist in general. On the contrary, Majorana physics is robust provided that only one single transverse mode contributes with a Majorana pair. Finally, we analyse the robustness of Majorana physics with respect to magnetic orbital effects.Comment: 5 pages, 4 figure

Osteogenic effects of simvastatin-loaded mesoporous titania thin films

The use of statins in the field of bone regeneration is under current investigation due to the existing demand for non-toxic anabolic agents capable of enhancing bone formation in cases of substantial loss. Simvastatin, a coenzyme currently prescribed in clinics to inhibit cholesterol biosynthesis, has been proven to promote osteogenic differentiation by stimulating bone formation and inhibiting osteoclasts activity. We present the loading of simvastatin in mesoporous TiO2 thin films toward combining the pro-osteogenic properties of this molecule with the demonstrated bioactivity of titania. TiO2 thin films processing and characterization were carried out, as well as evaluation of MC3T3-E1 pre-osteoblasts viability when directly incubated with different concentrations of simvastatin, followed by the analysis of osteogenic activity promoted by simvastatin upon loading in the thin films. The accessible porosity of 36% quantified on the 95 ± 5 nm thick mesoporous thin films, together with pore diameters of 5.5 nm, necks between pores of 2.8 nm and interpore distances of 12 ± 2 nm allow the loading of the simvastatin molecule, as confirmed by FTIR spectroscopy. Simvastatin was found to promote MC3T3-E1 pre-osteoblasts viability at concentrations ≤0.01 g l−1, with a cytotoxicity threshold of 0.05 g l−1. We additionally found that film loadings with 0.001 g l−1 simvastatin promotes statistically higher MC3T3-E1 pre-osteoblast proliferation whereas a higher concentration of 0.01 g l−1 leads to statistically higher osteogenic activity (ALP synthesis), after 21 days of incubation, as compared to unloaded films. These results demonstrate the potential of simvastatin local administration based on bioactive mesoporous thin films to promote pro-osteogenic properties. By focusing this strategy on the coating of metallic prostheses, the supply of simvastatin to the target tissue can be favored and risks of systemic side effects will be reduced while enhancing the osteointegration of the implants.Fil: Lopez Alvarez, Miriam. Universidad de Vigo; EspañaFil: López Puente, Vanesa. Universidad de Vigo; EspañaFil: Rodriguez Valencia, Cosme. Universidad de Vigo; EspañaFil: Angelome, Paula Cecilia. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Liz Marzan, Luis M. Ikerbasque; EspañaFil: Serra, Julia. Universidad de Vigo; EspañaFil: Pastoriza Santos, Isabel. Universidad de Vigo; EspañaFil: Gonzalez, Pio. Universidad de Vigo; Españ