Compact cryogenic Kerr microscope for time-resolved studies of electron spin transport in microstructures

A compact cryogenic Kerr microscope for operation in the small volume of high-field magnets is described. It is suited for measurements both in Voigt and Faraday configuration. Coupled with a pulsed laser source, the microscope is used to measure the time-resolved Kerr rotation response of semiconductor microstructures with ~1 micron spatial resolution. The microscope was designed to study spin transport, a critical issue in the field of spintronics. It is thus possible to generate spin polarization at a given location on a microstructure and probe it at a different location. The operation of the microscope is demonstrated by time-resolved measurements of micrometer distance diffusion of spin polarized electrons in a GaAs/AlGaAs heterojunction quantum well at 4.2 K and 7 Tesla

Suppressed spin dephasing for 2D and bulk electrons in GaAs wires due to engineered cancellation of spin-orbit interaction terms

We report a study of suppressed spin dephasing for quasi-one-dimensional electron ensembles in wires etched into a GaAs/AlGaAs heterojunction system. Time-resolved Kerr-rotation measurements show a suppression that is most pronounced for wires along the [110] crystal direction. This is the fingerprint of a suppression that is enhanced due to a strong anisotropy in spin-orbit fields that can occur when the Rashba and Dresselhaus contributions are engineered to cancel each other. A surprising observation is that this mechanisms for suppressing spin dephasing is not only effective for electrons in the heterojunction quantum well, but also for electrons in a deeper bulk layer.Comment: 5 pages, 3 figure

Intel, Guadalajara Design Center

ITESO, A.C

Funciones cognitivas afectadas en paciente con ACV

El objetivo de este estudio consiste en determinar el perfil neuropsicológico en pacientes que han sufrido un accidente cerebrovascular y su impacto psicosocial. Se realizó un estudio descriptivo, bajo el enfoque empírico analítico; se hizo una evaluación neuropsicológica transversal en 3 pacientes de ambos géneros, entre 20 y 69 años del departamento de Rawson, en la ciudad de San Juan, que han sido diagnosticados en Centro Integral de Rehabilitación con ACV isquémico y en otros casos hemorrágico, con estudios de neuroimagen que así lo confirmaron. Se realizó un análisis sobre la base de un procedimiento clínico. Se encontró síndromes neuropsicológicos como, afasia, agnosia, apraxia gestual y heminegligencia. No se pudo establecer un cuadro sintomatológico único debido a la heterogeneidad de las lesiones que causa el cuadro. Se comprobó la incidencia del contexto familiar en el desarrollo del proceso de neurorehabilitación, así como el impacto en la estructura familiar que provoca la situación de discapacidad del paciente que ha sufrido un accidente cerebro vascular.Fil: Rizo Saffe, Valeria A

Impact of texture TDS and flavour TDS tasks and of chocolate-chip biscuit characteristics on oral processing features

[EN] The objective of the present study was to investigate differences in oral activity when biscuits of the same type but with subtle composition differences are consumed and how performing a Temporal Dominance of Sensations (TDS) task modifies the way one eats. In addition, comparisons were made between performing a texture TDS (T-TDS) and a flavour TDS (F-TDS). Oral activity while eating biscuits with and without conducting a TDS task was recorded using a 3.dimensional motion capture system to monitor the evolution of jaw movements. The results showed that oral activity evolved over the consumption time, differed depending on the texture of the sample and was affected to a small but significant extent when a TDS task was performed simultaneously (the differences averaged < 4 cycles, 1 s in duration, 0.1 cycles/s in frequency, and 1 mm in lateral displacement). The biscuit samples were affected equally. Almost no differences were found on comparing oral activity during the execution of the T-TDS and the F-TDS tasks. Overall, the present results show differences in oral activity even for food products of the same category with subtle differences in composition. Performing TDS tasks (regardless of their modality) during sample consumption affected the total number, frequency and lateral amplitude of the chewing movements which should be taken into account for future research. However, these differences were small and affected both samples equally.The authors are grateful to the Spanish Ministry of the Economy and Competitiveness (AGL-2016-75403-R, Spain) and to the Regional Government of Valencia (Project Prometeo 2017/189, Spain) for financial support.Rizo, A.; Jimenez-Pérez, I.; Camacho-García, A.; Fiszman, S.; Pérez-Soriano, P.; Tarrega, A. (2019). Impact of texture TDS and flavour TDS tasks and of chocolate-chip biscuit characteristics on oral processing features. Food Quality and Preference. 76:109-117. https://doi.org/10.1016/j.foodqual.2019.04.005S1091177

Numerical resolution of Emden's equation using Adomian polynomials

Purpose: In this paper the authors aim to show the advantages of using the decomposition method introduced by Adomian to solve Emden's equation, a classical non‐linear equation that appears in the study of the thermal behaviour of a spherical cloud and of the gravitational potential of a polytropic fluid at hydrostatic equilibrium. Design/methodology/approach: In their work, the authors first review Emden's equation and its possible solutions using the Frobenius and power series methods; then, Adomian polynomials are introduced. Afterwards, Emden's equation is solved using Adomian's decomposition method and, finally, they conclude with a comparison of the solution given by Adomian's method with the solution obtained by the other methods, for certain cases where the exact solution is known. Findings: Solving Emden's equation for n in the interval [0, 5] is very interesting for several scientific applications, such as astronomy. However, the exact solution is known only for n=0, n=1 and n=5. The experiments show that Adomian's method achieves an approximate solution which overlaps with the exact solution when n=0, and that coincides with the Taylor expansion of the exact solutions for n=1 and n=5. As a result, the authors obtained quite satisfactory results from their proposal. Originality/value: The main classical methods for obtaining approximate solutions of Emden's equation have serious computational drawbacks. The authors make a new, efficient numerical implementation for solving this equation, constructing iteratively the Adomian polynomials, which leads to a solution of Emden's equation that extends the range of variation of parameter n compared to the solutions given by both the Frobenius and the power series methods.This work has been supported by the Ministerio de Ciencia e Innovación, project TIN2009-10581

Learning Probabilistic Features for Robotic Navigation Using Laser Sensors

SLAM is a popular task used by robots and autonomous vehicles to build a map of an unknown environment and, at the same time, to determine their location within the map. This paper describes a SLAM-based, probabilistic robotic system able to learn the essential features of different parts of its environment. Some previous SLAM implementations had computational complexities ranging from O(Nlog(N)) to O(N2), where N is the number of map features. Unlike these methods, our approach reduces the computational complexity to O(N) by using a model to fuse the information from the sensors after applying the Bayesian paradigm. Once the training process is completed, the robot identifies and locates those areas that potentially match the sections that have been previously learned. After the training, the robot navigates and extracts a three-dimensional map of the environment using a single laser sensor. Thus, it perceives different sections of its world. In addition, in order to make our system able to be used in a low-cost robot, low-complexity algorithms that can be easily implemented on embedded processors or microcontrollers are used.This work has been supported by the Spanish Ministerio de Ciencia e Innovación (www.micinn.es), project TIN2009-10581