Pilot study of vegetation in the Alchichica-Perote region by remote sensing

A study of the application of satellite images to the identification of vegetation in a small area corresponding to the arid zone of Veracruz and part of Puebla is presented. This study is accomplished by means of images from the LANDSAT satellite obtained on January 19 and May 23, 1973. The interpretation of the different maps is made on the basis of information from the data bank of the Flora de Veracruz program, and various surveys made by land and air

Poisonous plants for cattle in Colombia: research perspectives

Even though Colombian cattle-farming makes an important contribution to the national economy it also has great potential for growth; however, this activity is carried out in areas where animals may become naturally exposed to poisonous plants, affecting their health and production. It is recognised that some plants may damage the livestock sector in countries placing an important emphasis on cattle-rearing. Such problem has received scarce attention from academic research in Colombia, and the efforts made to do so date from the 1930s, 1940s, 1970s and 1980s without having had continuity. Many of the studies done in Colombia have been orientated towards establishing nitrate and cyanogenic glycoside content, ignoring other toxic metabolites. Likewise, certain vegetal species which can cause poisoning have not been fully studied, thereby hampering their management and treatment. It is thus important that studies are carried out in greater depth in Colombia concerning poisonous plants affecting livestock. A methodology is thus proposed which includes a search for initial information about suspicious plants, reproducing such poisoning experimentally (selecting the animal species, route, presentation and administration time, and evaluating effects) and searching for the chemical responsible for causing the poisoning. All these aspects are dealt with in the present review.Además de un gran potencial de crecimiento, la ganadería bovina colombiana tiene un importante aporte a la economía nacional. Esta actividad se desarrolla en áreas donde los animales pueden exponerse naturalmente a plantas tóxicas, afectando su salud y producción. En países con una importante vocación ganadera se reconocen las plantas que pueden menoscabar el sector pecuario. En Colombia, escasamente ha sido estudiada esta problemática y los esfuerzos por hacerlo datan de las décadas de 1930, 1940, 1970 y 1980, sin que haya habido continuidad en los mismos. Muchos de los estudios realizados en el país han estado orientados a establecer el contenido de nitratos y glucósidos cianogénicos, ignorando otros metabolitos tóxicos. Así mismo, existen intoxicaciones por ciertas especies de vegetales que no han sido plenamente estudiadas, dificultando su manejo y tratamiento. Es importante que en el país se investigue con mayor profundidad sobre las plantas tóxicas de interés pecuario y para ello se propone una metodología que incluye selección de la planta sospechosa, reproducción experimental de la intoxicación (elección de la especie animal, vía, presentación y tiempo de administración y evaluación de efectos) y búsqueda de principios responsables de causar la intoxicación; estos aspectos se abordan en la presente revisión.Facultad de Ciencias Veterinaria

Poisonous plants for cattle in Colombia: research perspectives

Even though Colombian cattle-farming makes an important contribution to the national economy it also has great potential for growth; however, this activity is carried out in areas where animals may become naturally exposed to poisonous plants, affecting their health and production. It is recognised that some plants may damage the livestock sector in countries placing an important emphasis on cattle-rearing. Such problem has received scarce attention from academic research in Colombia, and the efforts made to do so date from the 1930s, 1940s, 1970s and 1980s without having had continuity. Many of the studies done in Colombia have been orientated towards establishing nitrate and cyanogenic glycoside content, ignoring other toxic metabolites. Likewise, certain vegetal species which can cause poisoning have not been fully studied, thereby hampering their management and treatment. It is thus important that studies are carried out in greater depth in Colombia concerning poisonous plants affecting livestock. A methodology is thus proposed which includes a search for initial information about suspicious plants, reproducing such poisoning experimentally (selecting the animal species, route, presentation and administration time, and evaluating effects) and searching for the chemical responsible for causing the poisoning. All these aspects are dealt with in the present review.Además de un gran potencial de crecimiento, la ganadería bovina colombiana tiene un importante aporte a la economía nacional. Esta actividad se desarrolla en áreas donde los animales pueden exponerse naturalmente a plantas tóxicas, afectando su salud y producción. En países con una importante vocación ganadera se reconocen las plantas que pueden menoscabar el sector pecuario. En Colombia, escasamente ha sido estudiada esta problemática y los esfuerzos por hacerlo datan de las décadas de 1930, 1940, 1970 y 1980, sin que haya habido continuidad en los mismos. Muchos de los estudios realizados en el país han estado orientados a establecer el contenido de nitratos y glucósidos cianogénicos, ignorando otros metabolitos tóxicos. Así mismo, existen intoxicaciones por ciertas especies de vegetales que no han sido plenamente estudiadas, dificultando su manejo y tratamiento. Es importante que en el país se investigue con mayor profundidad sobre las plantas tóxicas de interés pecuario y para ello se propone una metodología que incluye selección de la planta sospechosa, reproducción experimental de la intoxicación (elección de la especie animal, vía, presentación y tiempo de administración y evaluación de efectos) y búsqueda de principios responsables de causar la intoxicación; estos aspectos se abordan en la presente revisión.Facultad de Ciencias Veterinaria

Spacetime-Filling Branes and Strings with Sixteen Supercharges

We discuss branes whose worldvolume dimension equals the target spacetime dimension, i.e. ``spacetime-filling branes''. In addition to the D9-branes, there are 9-branes in the NS-NS sectors of both the IIA and IIB strings. The worldvolume actions of these branes are constructed, via duality, from the known actions of branes with codimension larger than zero. Each of these types of branes is used in the construction of a string theory with sixteen supercharges by modding out a type II string by an appropriate discrete symmetry and adding 32 9-branes. These constructions are related by a web of dualities and each arises as a different limit of the Horava-Witten construction.Comment: 43 pages, LaTeX, 8 figures, uses html.sty, version to appear in Nucl. Phys.