Does the Pulvinar-Lp Complex Contribute to Motor Programming?

[Abstract] Extracellular unit recording studies in the pulvinar lateral posterior complex (Pui-LP) of behaving monkeys have shown a response property not previously reported. In monkeys performing aimed arm reaching movements towards frontally located targets some cells showed a change in activity beginning 495 ± 84 ms before the onset of the reaching movement. This change in frequency precedes that observed in primary motor and parietal posterior cortex for reaching movements. These findings seem to indicate the involvement of the Pul-LP in motor functions and suggest its possible contribution to motor programming.Comisión Asesora de Investigacion Cientifica y Tecnica (España); PR83-210

FUZZY SPEED CONTROL FOR TRAJECTORY FOLLOW-UP OF A ROBOT MOVING ON VERTICAL SURFACES

Este artículo presenta el diseño de un controlador fuzzy aplicado en el control de trayectorias en un robot móvil que se desplazara sobre superficies verticales con la finalidad de realizar operaciones de inspección y limpieza en tanques de almacenamiento de hidrocarburos. En la primera etapa se realiza la identificación de cada uno de los actuadores (motores DC). En la segunda etapa se presenta el diseño del controlador de velocidad fuzzy con el cual se podrán seguir las trayectorias determinadas. Y finalmente se presenta el algoritmo que le permitirá al robot determinar cuáles son los puntos más críticos de la superficie a inspeccionar y cual será camino que deberá seguir el robot móvil sobre la superficie.This paper shows the design of fuzzy speed control of trajectories in a mobilerobot. This robot can move on vertical surfaces of storage tanks for exploration, inspection and cleaning tasks. While the first step involvedactuators (DC motors) identification, the second step presented fuzzy control speed, which can be used for trajectory control. Finally, the genetic algorithm was implemented to obtain optimal trajectory of critical points on the surface where the robot is to follow its predetermined trajectory

Sturmian morphisms, the braid group B_4, Christoffel words and bases of F_2

We give a presentation by generators and relations of a certain monoid generating a subgroup of index two in the group Aut(F_2) of automorphisms of the rank two free group F_2 and show that it can be realized as a monoid in the group B_4 of braids on four strings. In the second part we use Christoffel words to construct an explicit basis of F_2 lifting any given basis of the free abelian group Z^2. We further give an algorithm allowing to decide whether two elements of F_2 form a basis or not. We also show that, under suitable conditions, a basis has a unique conjugate consisting of two palindromes.Comment: 25 pages, 4 figure

Detección de parásitos gastrointestinales en hurones (Mustela putorius furo) mediante análisis coprológico

The aim of this study was to determine the presence of zoonotic gastrointestinal parasites by coprological examination in ferrets (Mustela putorius furo) reared as pets and the role of sex and age. The faeces of 30 ferrets were analysed, 16 [53.3%] from pet stores and 14 [46.7%] from homes in the city of Santiago and Concepción, Chile. Burrows' coprological technique was used for the diagnosis, which allows detecting eggs of protozoan helminths, cysts and trophozoites Three samples (10%) tested positive for protozoa, one for Entamoeba coli, in a 6 month old male from a pet store, and two for Endolimax nana in a 3-month-old female and a 2-year-old male from private homes. This would be the first record for the two species of protozoa commensals in ferrets in Chile, which were probably acquired by the close contact of mustelids with humans.El objetivo del estudio fue determinar la presencia de parásitos gastrointestinales zoonóticos mediante examen coproparasitológico en hurones (Mustela putorius furo) criados como mascotas y el rol de las variables sexo y edad. Se analizaron las heces de 30 hurones, 16 [53.3%] de tiendas de mascotas y 14 [46.7%] de hogares de la ciudad de Santiago y Concepción, Chile. Para el diagnóstico se utilizó la técnica coproparasitaria de Burrows, que permite detectar huevos de helmintos, quistes y trofozoítos de protozoos. Tres muestras (10%) resultaron positivas a protozoos, una a Entamoeba coli, en un macho de 6 meses de una tienda de mascotas, y dos a Endolimax nana en una hembra de 3 meses y un macho se 2 años, ambos de hogares. Este sería el primer registro para las dos especies de protozoos comensales en hurones en Chile, los que probablemente fueron adquiridos por el estrecho contacto de los mustélidos con los humanos. &nbsp

A pilot field evaluation on heat stress in sugarcane workers in Costa Rica: What to do next?

BACKGROUND: Climate change is producing major impacts including increasing temperatures in tropical countries, like Costa Rica, where the sugarcane industry employs thousands of workers who are exposed to extreme heat. OBJECTIVES: This article outlines a pilot qualitative evaluation of working conditions and heat in the sugarcane industry. DESIGN: A literature review, direct observations and exploratory interviews with workers were conducted to reach a preliminary understanding of the dimensions of heat-related health issues in the sugarcane industry, as a basis for the design of future studies. RESULTS: The industry employs temporary workers from Nicaragua and Costa Rica as well as year-round employees. Temporary employees work 12-hour shifts during the harvest and processing ('zafra') season. In many cases, sugarcane field workers are required to carry their own water and often have no access to shade. Sugar mill workers are exposed to different levels of heat stress depending upon their job tasks, with the most intense heat and workload experienced by the oven ('caldera') cleaners. CONCLUSIONS: Research is needed to achieve better understanding of the multiple factors driving and interacting with heat exposures in the sugarcane industry in order to improve the health and safety of workers while maintaining worker productivity