Mexico.

Examina la geografía,la historia,la economía,la sociedad y la cultura de Mexico. Incluye actividades de cartografía y datos interesantes sobre la geografía, la flora y la fauna. Al final hay una relación alfabética de las palabras típicas mexicanas, con la pronunciación fgurada para los lectores de lengua inglesa. Hay un glosario final.

La capacitación para directivos de escuelas primarias en el estado de Coahuila, Mexico.

Mejorar la calidad educativa mediante la capacitación a los directivos de nivel primaria en el estado de Coahuila. Capacitar a las figuras directivas del nivel mediante el diplomado para Directivos de Escuelas Primarias. Promover que los directivos de Sector Rural Tres utilicen una plataforma tecnológica como herramienta de apoyo para mejorar su desempeño profesional. Promover y valorar el trabajo colaborativo que se base en la tecnología como estrategia didáctica de generación de nuevo conocimiento que impacte su labor de directivos. Valorar el enfoque educativo en base a la tecnología con el propósito de atender con eficacia las necesidades y retos actuales a las que se enfrentan las escuelas primarias del sector rural tres. Analizar las estrategias y metodología con las que el di9rectivo escolar ejerce sus competencias en la institución, tanto en su estructura (organización), funcionamiento (gestión) como la cultura del grupo humano que lo constituye. Se ha estudiado siguiendo un diseño cualitativo y por un estudio de caso, asimismo se utiliza la observación y la entrevista para la recolección de datos. Para identificar las características con las que una persona se comporta y actúa, en este caso los directivos de las escuelas primarias del Sector Rural Tres del Estado de Coahuila sujetos a estudio, se propone realizar una serie de observaciones de situaciones cotidianas, poniendo énfasis en aquellas que pueden reflejar cambios en consecuencia del comportamientos de los directivos; una segunda opción para conocer a los directivos, es la aplicación de entrevistas al personal, buscando en su opinión un reflejo de satisfacción o contradicción al comportamiento establecido por los directivos; con la aplicación de ambas técnicas (observación y entrevista) se busca construir un esquema del comportamiento de los directivos del Sector Rural Tres. La población se conforma de directores de educación primaria, supervisores y jefe de sector Rural III, distribuidos en los municipios de Arteaga, Saltillo y Ramos Arizpe, Coahuila, México. Para el desarrollo de la propuesta fue necesario elaborar o diseñar las guías tanto de observación como la de entrevista, implica una gran importancia, porque permite tener en cuenta los elementos necesarios y pertinentes para todas las acciones de recolección de información, estandarizando la información a identificar en cas acción de la propuesta. La escuela no solo se limita a los espacios físicos de la escuela primaria sino a todas las escuelas primarias del Sector Rural Tres de Coahuila que quieran integrarse a la comunidad virtual de aprendizaje mediado a través del uso de la tecnología. Esta iniciativa es de involucrar a otras instituciones de la misma zona escolar para genera e incrementar las expectativas de los directivos a través del uso de la tecnología y que sus escuelas sean reconocidas en sus logros académicos, el director es el gestor que inicia un proceso de vinculación entre instituciones liderando esta iniciativa y logra una situación más comprometida hacía su propia institución al intercambiar experiencias y conocimientos con los demás miembros del Sector Rural Tres. Los ámbitos de desarrollo que el director apuntala se refieren al proceso de enseñanza-aprendizaje buscando mejoras en los métodos y estrategias pedagógicas. La utilización de materiales educativos, áreas de interacción y de aprendizaje científico, áreas que han sido desperdiciadas como recursos para mejorar el aprendizaje en los alumnos, otro elemento, es el ambiente de trabajo adecuado para eficientar los procesos administrativos que realizan los docentes así como las líneas estratégicas de capacitación del personal, por último la vinculación y colaboración con los padres de familia, estableciendo mecanismos de comunicación, cooperación y apoyo en los procesos técnico pedagógicos y administrativos. En las reuniones será necesario generar estrategias o toma de decisiones que trascienda en la institución, el directivo utiliza diferentes estímulos adicionales lo que permite el análisis de la situación y toma de decisiones adecuadas.

Shifts in resident bird communities associated with cloud forest patch size in Central Veracruz, Mexico

Avian communities in cloud forests have high levels of endemism and are at major risk given the accelerated rate of habitat fragmentation. Nevertheless, the response of these communities to changes in fragment size remains poorly understood. We evaluated species richness, bird community density, community composition, and dominance as indicators of the response to fragment size in a fragmented cloud forest landscape in central Veracruz, Mexico. Medium-sized fragments had statistically higher than expected species richness and more even communities, which may be a reflection of the intermediate disturbance hypothesis, in which medium-sized fragments are exploited by both forest and disturbance-associated species. Bird density also reached higher values in medium-sized fragments, which may indicate a carrying capacity in this habitat. However, large cloud forest fragments had a distinct taxonomic and functional composition, attributable to an increased number of understory insectivore species and canopy frugivores. By comparison, omnivorous species associated with human-altered habitats were more abundant in smaller fragments. Hence, although medium-sized cloud forest fragments had higher species richness and high bird density, large forest tracts maintained a distinct avian community composition, particularly of insectivorous and frugivorous species. Furthermore, the underlying response to fragmentation can only be properly addressed when contrasting several community attributes, such as richness, density, composition, and species dominance. Therefore, cloud forest conservation should aim to preserve the remaining large forest fragments to maintain comprehensive avian communities and avoid local extinctions.

Chemical composition and fermentation characteristics of grain and different parts of the stover from maize land races harvested at different growing periods in two zones of central Mexico

The objective of this work was to determine the rumen fermentation characteristics of maize land races used as forage in central Mexico. In vitro gas production (ml per 200 mg dry matter (DM)) incubations were carried out, and cumulative gas volumes were fitted to the Krishnamoorthy et al. (1991) model. The trial used a split-plot design with cultivation practices associated with maize colour (COL) as the main plot with three levels: white, yellow and black maize; growing periods (PER) were the split plots where PER1, PER2 and PER3 represented the first, second and third periods, respectively and two contrasting zones (Z1 = valley and Z2 = mountain) were used as blocking factors. The principal effects observed were associated with the maturity of the plants and potential gas production increased (P < 0.05) in stems (PER 1 = 51.8, PER2 = 56.3, PER3 = 58.4 ml per 200 mg DM) and in whole plant (PER 1 = 60.9, PER2 = 60.8, PER3= 70.9 ml per 200 mg DM). An inverse effect was observed with fermentation rates in leaves (P < 0.01) with 0.061, 0.053 and 0.0509 (per h) and in whole plant (P < 0.05) with 0.068, 0.057, 0.050 (per h) in PER1, PER2 and PER3 respectively. The digestibility of the neutral-detergent fibre (NDF) decreased with maturity especially in leaves (P < 0.05) with values of 0.71, 0.67 and 0.66 g/kg; in rachis (P < 0.01) 0.75, 0.72, and 0.65 in PER1, PER2 and PER3 respectively. The NDF content in leaves in leaves (668, 705 and 713 g/kg DM for PER1, PER2 and PER3, respectively), stems (580, 594 and 644 g/kg DM) and, husk (663, 774 and, 808 g/kg DM) increased (P < 0.05) with increasing plant maturity, rachis were significantly different between periods (P < 0.01). The structure with-the best nutritive characteristics was the husk, because it had the lowest fibre contents, especially in acid-detergent lignin, with values of 22.6, 28.6 and 37.6 g/kg DM in PER1, PER2 and PER3, respectively.

In situ degradability of dry matter and neutral-detergent fibre of thorn scrubland forage consumed by goats in the semi-arid region of north Mexico

Three goats provided with oesophageal and ruminal cannulae were used to determine variations in dry matter (DM) and neutral-detergent fibre (NDF) degradability of the forage consumed when grazing thorn scrubland in the semi-arid region of north Mexico, during two consecutive dry and wet periods. Ingesta samples were incubated intraruminally, the data were fitted to the exponential equation P = a + b (1-e(-ct)) and statistically analysed using a randomized-block design. Organic matter and crude protein (CP) contents were higher (P < 0.05) in the wet seasons. Values of NDF were similar in dry and wet season of both years whereas higher numerical values of acid-detergent fibre (ADF), lignin and cellulose were registered in the dry seasons. DM and NDF degradabilities after 24 and 48 h of ruminal incubation were higher (P < 0.05) in the wet seasons. Higher values (P < 0.05) in DM and NDF bag losses at zero time (A fraction) were registered in the two wet seasons. The insoluble but fermentable DM and NDF (B fractions) were higher (P < 0.05) in the 1999 wet season and variable in the rest of the studied period. Numerically higher values of DM and NDF c fraction were found in wet periods, whereas DM and NDF potential degradabilities were higher (P < 0.05) in the wet season in 1999 and similar across seasons in 2000. Lowest (P < 0.05) contents of CP in grazed forage, DM and NDF degradabilities after 48 h of ruminal incubation, and A, and B, and c fractions were observed in the dry seasons. Thus, these results may be related to both the lower feeding value of forage consumed by the animals and lower performance of livestock during this period. Then, the DM and NDF degradability after 48 h, together with the insoluble but fermentable matter and the c fraction permit the nutritive value of the forage consumed by grazing goats to be accurately described.

Study of the lactation curve in dairy cattle on farms in Central Mexico

Accurate knowledge of lactation curves has an important relevance to management and research of dairy production systems. A number of equations have been proposed to describe the lactation curve, the most widely applied being the gamma equation. The objective of this work was to compare and evaluate candidate functions for their predictive ability in describing lactation curves from central Mexican dairy cows reared under 2 contrasting management systems. Five equations were considered: Gaines ( exponential decay), Wood ( gamma equation), Rook ( Michaelis-Menten x exponential), and 2 more mechanistic ones (Dijkstra and Pollott). A database consisting of 701 and 1283 records of cows in small-scale and intensive systems, respectively, was used in the analysis. Before analysis, the database was divided into 6 groups representing first, second, and third and higher parity cows in both systems. In all cases except second and above parity cows in small-scale systems, all models improved on the Gaines equation. The Wood equation explained much of the variation, but its parameters do not have direct biological interpretation. Although the Rook equation fitted the data well, some of the parameter estimates were not significant. The Dijkstra equation consistently gave better predictions, and its parameters were usually statistically significant and lend themselves to physiological interpretation. As such, the differences between systems and parity could be explained due to variations in theoretical initial milk production at parturition, specific rates of secretory cell proliferation and death, and rate of decay, all of which are parameters in the model. The Pollott equation, although containing the most biology, was found to be over-parameterized and resulted in nonsignificant parameter estimates. For central Mexican dairy cows, the Dijkstra equation was the best option to use in describing the lactation curve.

Modeling small-scale dairy farms in central Mexico using multi-criteria programming

Milk supply from Mexican dairy farms does not meet demand and small-scale farms can contribute toward closing the gap. Two multi-criteria programming techniques, goal programming and compromise programming, were used in a study of small-scale dairy farms in central Mexico. To build the goal and compromise programming models, 4 ordinary linear programming models were also developed, which had objective functions to maximize metabolizable energy for milk production, to maximize margin of income over feed costs, to maximize metabolizable protein for milk production, and to minimize purchased feedstuffs. Neither multicriteria approach was significantly better than the other; however, by applying both models it was possible to perform a more comprehensive analysis of these small-scale dairy systems. The multi-criteria programming models affirm findings from previous work and suggest that a forage strategy based on alfalfa, rye-grass, and corn silage would meet nutrient requirements of the herd. Both models suggested that there is an economic advantage in rescheduling the calving season to the second and third calendar quarters to better synchronize higher demand for nutrients with the period of high forage availability.

Analysis of the calving pattern of herds in small-scale dairy systems in central Mexico

This study sets out to find the best calving pattern for small-scale dairy systems in Michoacan State, central Mexico. Two models were built. First, a linear programming model was constructed to optimize calving pattern and herd structure according to metabolizable energy availability. Second, a Markov chain model was built to investigate three reproductive scenarios (good, average and poor) in order to suggest factors that maintain the calving pattern given by the linear programming model. Though it was not possible to maintain the optimal linear programming pattern, the Markov chain model suggested adopting different reproduction strategies according to period of the year that the cow is expected to calve. Comparing different scenarios, the Markov model indicated the effect of calving interval on calving pattern and herd structure.