Robot Impedance Control and Passivity Analysis with Inner Torque and Velocity Feedback Loops

Impedance control is a well-established technique to control interaction forces in robotics. However, real implementations of impedance control with an inner loop may suffer from several limitations. Although common practice in designing nested control systems is to maximize the bandwidth of the inner loop to improve tracking performance, it may not be the most suitable approach when a certain range of impedance parameters has to be rendered. In particular, it turns out that the viable range of stable stiffness and damping values can be strongly affected by the bandwidth of the inner control loops (e.g. a torque loop) as well as by the filtering and sampling frequency. This paper provides an extensive analysis on how these aspects influence the stability region of impedance parameters as well as the passivity of the system. This will be supported by both simulations and experimental data. Moreover, a methodology for designing joint impedance controllers based on an inner torque loop and a positive velocity feedback loop will be presented. The goal of the velocity feedback is to increase (given the constraints to preserve stability) the bandwidth of the torque loop without the need of a complex controller.Comment: 14 pages in Control Theory and Technology (2016

Spontaneous Embedding of DNA Mismatches Within the RNA:DNA Hybrid of CRISPR-Cas9.

CRISPR-Cas9 is the forefront technology for editing the genome. In this system, the Cas9 protein is programmed with guide RNAs to process DNA sequences that match the guide RNA forming an RNA:DNA hybrid structure. However, the binding of DNA sequences that do not fully match the guide RNA can limit the applicability of CRISPR-Cas9 for genome editing, resulting in the so-called off-target effects. Here, molecular dynamics is used to probe the effect of DNA base pair mismatches within the RNA:DNA hybrid in CRISPR-Cas9. Molecular simulations revealed that the presence of mismatched pairs in the DNA at distal sites with respect to the Protospacer Adjacent Motif (PAM) recognition sequence induces an extended opening of the RNA:DNA hybrid, leading to novel interactions established by the unwound nucleic acids and the protein counterpart. On the contrary, mismatched pairs upstream of the RNA:DNA hybrid are rapidly incorporated within the heteroduplex, with minor effect on the protein-nucleic acid interactions. As a result, mismatched pairs at PAM distal ends interfere with the activation of the catalytic HNH domain, while mismatches fully embedded in the RNA:DNA do not affect the HNH dynamics and enable its activation to cleave the DNA. These findings provide a mechanistic understanding to the intriguing experimental evidence that PAM distal mismatches hamper a proper function of HNH, explaining also why mismatches within the heteroduplex are much more tolerated. This constitutes a step forward in understanding off-target effects in CRISPR-Cas9, which encourages novel structure-based engineering efforts aimed at preventing the onset of off-target effects

A methodology for developing Distributed Generation scenarios in urban areas using geographical information systems

The implementation of Distributed Generation (DG) may lead to increased pollutant emissions that adversely affect air quality. This work presents a systematic methodology to characterise DG installation in urban basins. First, a set of parameters that characterise a DG implementation scenario is described. Second, a general approach using Geographic Information Systems (GIS) data is presented. Third, the methodology is demonstrated by application to the South Coast Air Basin (SoCAB) of California. Results show that realistic scenarios in the SoCAB concentrate DG technologies nearby industrial zones and introduce pollutant mass increments no larger than 0.43% with respect to baseline emissions.We graciously acknowledge the financial support of the California Energy Commission, sponsor of this work, and the significant leadership and contributions of Marla Mueller, our Contract Manager. M. Carreras and M. Medrano thank the continuing support of the Balsells-Generalitat de Catalunya Fellowship

Estrategia aplicada a simulador de negocios Capstone

El siguiente documento tiene como objetivo describir, analizar y reflexionar sobre la gestión estratégica de una compañía dentro de la industria de sensores durante un tiempo de ocho años en un ambiente virtual, el cual es facilitado por Capsima a través de su aplicación de simulador de negocios Capstone. De igual forma, se presentan conceptos, teorías y estudios de empresas líderes sobre estrategias de negocios que permiten entender con mayor profundidad el tema

Incidencia de los Factores psicosociales en empleados del sector público de la provincia de Tarma

Objective. Describe the incidence of psychosocial factors in public sector employees in the province of Tarma. Methods. The type of investigation was basic; descriptive level, descriptive-simple design; The instrument used was the questionnaire on psychosocial factors by Pando et al. (2016), whose dimensions were: workplace conditions, workload, content and characteristics of the task, job demands, job role and career development, social interaction and organizational aspects, and satisfaction with performance compensation; The sample consisted of 120 collaborators from 3 public institutions; the sampling was non-probabilistic - intentional. Results. Psychosocial factors moderately affect the job performance of public sector employees in the province of Tarma. Conclution. The degree of incidence of the factors in the behavior and performance of workers is moderately pernicious, and in the medium term may be a determining aspect in the development and generation of some occupational diseases such as stress and burnout.Objetivo. Describir la incidencia de los factores psicosociales en empleados del sector público de la provincia de Tarma. Métodos. El tipo de investigación fue básico; nivel descriptivo, diseño descriptivo-simple; el instrumento utilizado fue el cuestionario de factores psicosociales de Pando et al. (2016), cuyas dimensiones fueron: condiciones del lugar de trabajo, carga de trabajo, contenido y características de la tarea, exigencias laborales, papel laboral y desarrollo de la carrera, interacción social y aspectos organizacionales y satisfacción con la remuneración del rendimiento; la muestra estuvo conformada por 120 colaboradores de 3 instituciones públicas; el muestreo fue no probabilístico - intencional. Resultados. Los factores psicosociales inciden moderadamente en el rendimiento laboral de los empleados del sector público de la provincia de Tarma. Conclusión. El grado de incidencia de los factores en el comportamiento y rendimiento de los trabajadores, es medianamente pernicioso, pudiendo ser a mediano plazo un aspecto determinante en el desarrollo y generación de algunas enfermedades laborales como el estrés y burnout

Hypothetical Pneumocystis jirovecii Transmission from Immunocompetent Carriers to Infant

Revue en accès libre via : http://www.cdc.gov/ncidod/eid/index.htmInternational audienc

Vertical Transmission of Pneumocystis jirovecii in Humans

This study is part of the project “Pneumocystis Pathogenomics: Unravelling the Colonization-to-Disease Shift,” a Coordination Action supported by the European Commission (ERANET PathoGenoMics). This study was partially supported by the Spanish Ministry of Health (FIS 03/1743). M.A.M.-C. and C.d.l.H. were supported by the Spanish Ministry of Health (FIS CP-04/217 and FIS CM-04/146).Ye

Pneumocystis jirovecii Transmission from Immunocompetent Carriers to Infant

We report a case of Pneumocystis jirovecii transmission from colonized grandparents to their infant granddaughter. Genotyping of P. jirovecii showed the same genotypes in samples from the infant and her grandparents. These findings support P. jirovecii transmission from immunocompetent carrier adults to a susceptible child

Abrasive Wear Behavior of Al–4Cu–1.5Mg–WC Composites Synthesized through Powder Metallurgy

Different Al–4Cu–1.5Mg/WC composites were synthesized through powder metallurgy to establish the effect of WC particle addition on the abrasive wear behavior of an Al–4Cu–1.5Mg (wt. %) alloy. The wear tests were performed using a pin-on-disc tribometer at room temperature in dry conditions using SiC abrasive sandpaper as a counterbody and tribometer of linear configuration. The results showed that WC additions increase the hardness of the Al–4Cu–1.5Mg alloy due to the strengthening effect of particle dispersion in the aluminum matrix, which generates an improvement in the wear resistance of the composites by preventing direct contact of the sample with the counterbody, in turn delaying the plastic deformation phenomena responsible for the degradation sequence. In addition, the dominant wear mechanism was abrasive wear, and the increased friction coefficient did not bring a rapid wear rate, which was related to the enhanced deformation resistance due to the high hardness