Estimando el nivel agroecologico de una finca: una herramienta de evaluación para agricultores

Climate change and inappropriate landscape management have increased the intensity and severity of wildfires in Chilean Mediterranean ecosystems, including sclerophyllous forests. During the 2016-2017 summer, a megafire affected more than 5,000 km2 in the country, compromising these ecosystems. Despite advances on aboveground recovery following fires, belowground restoration has been less explored in these forests. This study aimed to evaluate early responses of simple and approachable soil health indicators to different organic amendments and vegetation establishment methods. Six months following organic amendment application (compost, swine or poultry manure) and plant establishment (either seeds or seedlings), soil health indicators including heterotrophic microbial counts (colony-forming-units -CFUs) and physicochemical characteristics were determined in a fire-affected sclerophyllous Mediterranean forest of central Chile. The organic amendments, plant establishment, and their interaction, significantly affected soil CFUs, while chemical parameters including pH and electrical conductivity were solely affected by organic amendment. The swine manure-plantation treatment and the unburned reference forest had four- and five-fold more CFUs than the control, respectively. No effect was observed in soil gravimetric water content, organic matter content, or aggregate distribution. Overall, less marked effects were registered in soil physicochemical conditions as compared to microbial counts.Aunque existen muchas metodologías disponibles para evaluar el desempeño de un agroecosistema (sostenibilidad, resiliencia, calidad del suelo y salud de las plantas, niveles de biodiversidad, etc.), aún es necesario desarrollar una metodología para ser utilizada a nivel de campo por investigadores y agricultores para evaluar si los sistemas agrícolas encuestados se basan o no en principios agroecológicos. El desarrollo de dicha metodologia es clave para determinar si los agricultores en transición están en el camino agroecológico correcto. Para satisfacer esta necesidad, se desarrolló y probó una herramienta metodológica con la participación de nueve agricultores japoneses en tres prefecturas (Kyoto, Hiroshima y Hyogo). La metodología consta de dos partes. La primera es una encuesta de evaluación simple y rápida basada en la calificación de ocho indicadores que permite evaluar si las prácticas utilizadas por los agricultores coinciden con los principios agroecológicos. La segunda parte utiliza los mismos indicadores para definir un “umbral”, por debajo del cual se estima que un sistema agrícola aún no está “basado en la agroecología”. Este proceso permite contextualizar la herramienta para permitir que los agricultores reflexionen y utilicen la herramienta como guía para adoptar o ajustar sus prácticas basadas en los principios de la agroecología, instándolos a cambiar el diseño y el manejo de la finca, a fin de optimizar la función del agroecosistema

Understanding the importance of selenium and selenoproteins in muscle function

Selenium is an essential trace element. In cattle, selenium deficiency causes dysfunction of various organs, including skeletal and cardiac muscles. In humans as well, lack of selenium is associated with many disorders, but despite accumulation of clinical reports, muscle diseases are not generally considered on the list. The goal of this review is to establish the connection between clinical observations and the most recent advances obtained in selenium biology. Recent results about a possible role of selenium-containing proteins in muscle formation and repair have been collected. Selenoprotein N is the first selenoprotein linked to genetic disorders consisting of different forms of congenital muscular dystrophies. Understanding the muscle disorders associated with selenium deficiency or selenoprotein N dysfunction is an essential step in defining the causes of the disease and obtaining a better comprehension of the mechanisms involved in muscle formation and maintenance

A Stable Difference Scheme for Computing Motion of Level Surfaces by the Mean Curvature

A difference scheme is introduced for computing the motion of level surfaces moved by the mean curvature. This scheme is proved to be stable in the maximum norm so that the computation can be completed without over-flow