Modulación de la actividad dopaminérgica en el núcleo Acumbens durante la formación y evocación de memoria al sabor

"El objetivo de este trabajo fue evaluar a través de microdiálisis en ratas en libre movimiento los cambios en los niveles extracelulares de DA en el NAc shell, durante el consumo novedoso de una solución azucarada (azúcar 10%), y tras el consumo agudo durante 2 días / 15 minutos de un sabor ligeramente familiar; así como durante el consumo de un sabor altamente familiar tras un consumo crónico de 14 días, como único líquido de ingesta ad libitum, basándose en el modelo gustativo apetitivo.

Changes in Prices After an Excise Tax to Sweetened Sugar Beverages Was Implemented in Mexico: Evidence from Urban Areas

In 2014 an excise tax to non-alcoholic sweetened beverages (SSB) was implemented in Mexico. The objective of this paper is to study whether and to what degree these taxes passed-through onto SSB prices in urban areas overall and by region, type of beverage and package size. Prices were obtained from the National Institute of Statistics and Geography from 2011 to 2014. We applied a pre-post quasi-experimental approach using fixed effects models. In sensitivity analysis we applied other model specifications to test the robustness of the findings and we also present weighted estimations based on household purchases. The dependent variables are real prices of a specific beverage category; the main independent variables are dummies for each month of 2014, and the models adjust for time trends and seasonality. Results suggest that the SSB tax passed along to consumers for all SSBs and we found overshifting for the carbonated SSBs. A greater effect is seen among the small package sizes, and we see heterogeneous effects by region. Estimating the effect of the tax on prices is important to understand the potential effect on consumption

Equilibrium of Global Amphibian Species Distributions with Climate

A common assumption in bioclimatic envelope modeling is that species distributions are in equilibrium with contemporary climate. A number of studies have measured departures from equilibrium in species distributions in particular regions, but such investigations were never carried out for a complete lineage across its entire distribution. We measure departures of equilibrium with contemporary climate for the distributions of the world amphibian species. Specifically, we fitted bioclimatic envelopes for 5544 species using three presence-only models. We then measured the proportion of the modeled envelope that is currently occupied by the species, as a metric of equilibrium of species distributions with climate. The assumption was that the greater the difference between modeled bioclimatic envelope and the occupied distribution, the greater the likelihood that species distribution would not be at equilibrium with contemporary climate. On average, amphibians occupied 30% to 57% of their potential distributions. Although patterns differed across regions, there were no significant differences among lineages. Species in the Neotropic, Afrotropics, Indo-Malay, and Palaearctic occupied a smaller proportion of their potential distributions than species in the Nearctic, Madagascar, and Australasia. We acknowledge that our models underestimate non equilibrium, and discuss potential reasons for the observed patterns. From a modeling perspective our results support the view that at global scale bioclimatic envelope models might perform similarly across lineages but differently across regions

El Equilibrio de las Especies con el Clima: Implicaciones en la Distribución Geográfica de los Vertebrados Terrestres

[EN] Climate has a central role in the physiology of species, which in turn, determine their geographic distributions. It is well known, since the biogeographical works of Buffon, Humbolt and Wallace, during the XVIII and XIX century, that sites climatically similar do not necessarily hold the same species assemblage. However, the scarce information available regarding the relationship between species and the environment has prevented scientists from addressing these issues thoroug hly, until recent times. It is possible to explore diverse biogeographic issues from the currently occupancy of species and its relation to climatic patterns; for example, the current degree of species’ equilibrium with climate, or why some regions that are climatically similar to those occupied by a species remain unoccupied by it. [ES] El clima juega un papel central en la fisiología de las especies que se refleja en sus áreas de distribución a escalas geográficas. Al respecto, es bien conocido desde los primeros estudios de Humbolt, Buffon y Wallace en los siglos XVIII y XIX, que no todos los sitios que son climáticamente similares presentan el mismo ensamblaje de especies; sin embargo, la falta de información sobre las especies y los ambientes no había permitido profundizar en el análisis de este tipo de preguntas, hasta ahora. Mediante el análisis de las condiciones climáticas de las áreas que habita una especie y cómo éstas cambian en el tiempo, se pueden explorar diversos temas biogeográficos; por ejemplo, el grado de equilibrio climático que tienen las especies en la actualidad, o cuántas regiones climáticamente similares a las áreas de distribución de una especie hay en otros lugares y por qué no está presente allá; o si son los factores históricos, como la deriva continental o qué tipo de barreras geográficas delimitan las áreas de distribución de las especies. En general, entender el papel que ha jugado y juega el clima en los procesos de las poblaciones y las especies que repercuten en su distribución geográfica es de interés teórico y aplicado, dado el presente cambio climático y la actual crisis de biodiversidad.Agradezco al Posgrado en Ciencias Biológicas de la UNAM por todas las facilidades otorgadas para concluir satisfactoriamente. Al CONACyT por otorgarme la beca doctoral para poder realizar mi doctorado. A los apoyos PAEP del Posgrado UNAM, con los cuales pude asistir a importantes congresos académicos. A mi tutor Dr. Enrique Martínez Meyer, tutor invitado Miguel B. Araújo y los miembros de mi comité tutoral Dr. Joaquín Arroyo Cabrales y Dr. Víctor Manuel G. Sánchez-Cordero Dávila por asesorarme, participar en valiosas discusiones en el tema de tesis y hacer valiosas recomendaciones durante el desarrollo del proyecto doctoral.Peer Reviewe

Estudio comparativo de las leyes que regulan los mercados de valores de México y Costa Rica para la elaboración de recomendaciones que actualicen el marco jurídico del mercado de valores de Nicaragua

Tesis (Licenciatura en Derecho)--Universidad Americana, Managua, 2001La presente tesis estudia el Mercado de Valores desde el punto de vista de la doctrina, elaborando un estudio de derecho comparado de las legislaciones de México y Costa Rica, utilizando como base los objetivos y principios de la regulación de Valores emitidos por la Organización Internacional de Comisiones de Valores, estudiando el marco jurídico que regula el Mercado de Valores de Nicaragua, conociendo los aspectos positivos y las necesidades de orden legal que impiden su desarrollo

Human impact gradient on mammalian biodiversity

Drastic changes have been caused by human influence in natural landscapes, which may exert an intensive effect on species loss. However, species loss from human pressure is not random but depends on a series of environmentally associated factors. Linking species traits to environmental attributes may allow us to detect the ecological impacts of habitat so that meaningful habitat degradation gradients can be identified. The relationships between environmental factors and species traits provide the basis for identifying those biological traits that make species more sensitive to disturbance. These relationships are also helpful to detect the geographic distribution of latent risk to reveal areas where biodiversity is threatened. Here, we identify a “Human Impact Gradient for Biodiversity (HIGB)” based on a three-table ordination method (RLQ analysis) and fourth-corner analysis to identify key species traits that are associated with environmental gradient. Species distribution and environmental geographic data were gathered nationwide to analyze 68 localities, which represent 27% of Mexico’s surface, including 211 species of mammals. Nine environmental variables (including biophysical, geophysical and land-use impacts) were analyzed by using the Geographic Information System. Three types of species’ traits were evaluated: locomotion, trophic habit and body size. We identified a human impact gradient, which was mainly determined by the percentage of the area that was covered by seedlings, the plant richness, the understory coverage percentage and the human settlement index. The most important species traits that are associated with non-human-impacted sites were carnivores, frugivores–herbivores and a body size that was greater than 17.8 kg; 25 species were selected by the decision criteria framework for species that were sensitive to degradation based on ecological function information. Conversely, granivores, fossorial and semifossorial traits were associated with highly impacted sites. The environmental attributes were mapped to highlight the spatial patterns of human risk for species. Finally, we highlighted the need to apply science-based monitoring to future research based on the decision criteria framework for selecting species that are sensitive to degradation

On Scrutinizing the Classical Polanyi Adsorption Potential Theory for Vapour Uptake Occurring in the Mesopores of Curved Shapes

One of the essential foundations of the classical Polanyi adsorption potential theory has been assessed with respect to the invariability with temperature of the so-called characteristic adsorption curves. This has been achieved both numerically and experimentally for nitrogen and numerically for argon adsorption onto spherical as well as onto cylindrical mesopore entities at 77.35 K and 87.29 K, respectively. The adsorption results in these spherical and cylindrical pores were obtained from an application of the Broekhoff–de Boer equation and compared to nitrogen experimental sorption data obtained from cylindrical SBA-15 and spherical SBA-16 pore systems. The characteristic curves obtained in both ways were consistent with each other

Affordability of Food and Beverages in Mexico between 1994 and 2016

We estimated the affordability of food and beverages by energy density and nutrient quality in Mexico and tested for differential trends in affordability over time and by income quintile. We used the National Income and Expenditures Survey from 1994 to 2016, and information on the caloric and nutrient content of food and beverages from Mexican food composition tables. We estimated food energy density (kcal/kg) and nutrient quality of food and beverages using the nutrient-rich food index (NRFI). Affordability of food and beverages was defined as household monthly income needed to purchase 1000 kcal. The affordability index was expressed by quintiles of energy density and quintiles of the NRFI and by income quintile over time. We found that more energy-dense foods and food and beverages with lower nutrient quality were more affordable compared to healthier food and beverages. Food categories with lower energy density and a higher NRFI became less affordable over time for most income groups, but the burden was higher for lower-income households. A comprehensive national strategy should be implemented to make healthier options more affordable and discretional foods and beverages with lower nutrient quality less affordable

Aplicación del código sanitario internacional en el SICA y en Nicaragua

Tesis (Lic. en Derecho)-Universidad Nacional Autónoma de Nicaragua, LeónUNAN-Leó

El derecho de la educación de niños y niñas con necesidades educativas en edad pre-escolar en la Escuela Especial-León

Tesis (Lic. en Ciencias de la Educación con Mención en Preescolar)-Universidad Nacional Autónoma de Nicaragua, LeónUNAN-Leó