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Diluted density. Urban planning in the Monterrey Metropolitan Area

Sheila Ferniza Quiroz Jesús Manuel Fitch Osuna (2021)

The Monterrey Metropolitan Area (mma) in Northern Mexico has had an expansive and dispersed growth in recent decades. In 35 years, the city doubled its population and grew 8 times in territory (Secretariat for Sustainable Development, 2020). As a mitigation measure and with the objective of repopulating the areas within the city, urban regulations have been promoted that allow higher density and building potentials in some municipalities; however, the efforts are isolated and without metropolitan coordination. What are the urban regulation guidelines in the municipalities of the mma? How dense are its municipalities? Where are located the densest areas of the city? The objective of this research is to establish the current state of local regulation regarding urban development and to map the housing density to identify the locations with the lowest and highest density at the mma. The gross density at the Ageb scale is mapped for the 18 municipalities of the mma through the QGis software; data from the Inegi 2020 National Population and Housing Census is used. It is found that the peripheral municipalities of recent incorporation to the mma, unlike those of greater urbanization, lack urban development plans, and that most of the municipalities do not have updated regulations based on the current laws. The areas with the highest density are located in the peripheral municipalities, associated with the construction of low-income mass housing, and those with the lowest density in interior municipalities in areas of higher socioeconomic status, diluting the small efforts of densification in the city.

Article

Artículo

density urban sprawl urban planning densidad expansión urbana planeación urbana HUMANIDADES Y CIENCIAS DE LA CONDUCTA HUMANIDADES Y CIENCIAS DE LA CONDUCTA

Seasonal and successional dynamics of size-dependent plant demographic rates in a tropical dry forest

Irving Saenz Pedroza Richard Feldman Casandra Reyes García Jorge Arturo Meave del Castillo Luz María del Carmen Calvo Irabien FILOGONIO MAY PAT JUAN MANUEL DUPUY RADA (2020)

Tropical forests are globally important for biodiversity conservation and climate change mitigation but are being converted to other land uses. Conversion of seasonally dry tropical forests (SDTF) is particularly high while their protection is low. Secondary succession allows forests to recover their structure, diversity and composition after conversion and subsequent abandonment and is influenced by demographic rates of the constituent species. However, how these rates vary between seasons for different plant sizes at different successional stages in SDTF is not known. The effect of seasonal drought may be more severe early in succession, when temperature and radiation are high, while competition and density-dependent processes may be more important at later stages, when vegetation is tall and dense. Besides, the effects of seasonality and successional stage may vary with plant size. Large plants can better compete with small plants for limiting resources and may also have a greater capacity to withstand stress. Weasked how size-dependent density, species density, recruitment andmortality varied between seasons and successional stages in a SDTF. We monitored a chronosequence in Yucatan, Mexico, over six years in three 0.1 ha plots in each of three successional stages: early (3 5 years-old), intermediate (18 20 years-old) and advanced (>50 years-old). Recruitment, mortality and species gain and loss rates were calculated from wet and dry season censuses separately for large (diameter > 5 cm) and small (1 5 cm in diameter) plants. We used linear mixed-effects models to assess the effects of successional stage, seasonality and their changes through time on demographic rates and on plant and species density. Seasonality affected demographic rates and density of large plants, which exhibited high wet-season recruitment and species gain rates at the early stage and high wet-season mortality at the intermediate stage, resulting in an increase in plant and species density early in succession followed by a subsequent stabilization. Small plant density decreased steadily after only 5 years of land abandonment, whereas species density increased with successional stage. A decline in species dominance may be responsible for these contrasting patterns. Seasonality, successional stage and their changes through time had a stronger influence on large plants, likely because of large among-plot variation of small plants. Notwithstanding the short duration of our study.

Article

CHRONOSEQUENCE RESAMPLING PLANT AND SPECIES DENSITY RECRUITMENT MORTALITY DRY SEASON RAINY SEASON SECONDARY FOREST SUCCESSION COMPETITION ENVIRONMENTAL FILTERING BIOLOGÍA Y QUÍMICA CIENCIAS DE LA VIDA BIOLOGÍA VEGETAL (BOTÁNICA) DESARROLLO VEGETAL DESARROLLO VEGETAL

Estudios teórico-computacionales sobre las interacciones entre moléculas antioxidantes y grafeno y sus nuevos derivados

BRENDA MANZANILLA VIVEROS (2021)

En este trabajo se presenta el estudio con Teoría de Funcionales de la Densidad (DFT, Density Funtional Theory) de diversos modelos finitos de grafeno y algunos de sus derivados, así como de antioxidantes endógenos como melatonina y algunos de sus análogos, y exógenos como el ácido chicórico (CA), la curcumina y el éster fenetílico del ácido cafeico (CAPE), para formar nanovectores que ayuden a reducir el estrés oxidativo. En la primera parte del proyecto se analizó el cambio en las propiedades químicas de diversos modelos finitos de grafeno y algunos de sus derivados, como son grafeno dopado con boro (B), nitrógeno (N) o fósforo (P), grafano, fluorografeno, grafino, grafidiino y óxido de grafeno. Para ello, se usaron los descriptores globales y locales de la reactividad de la DFT Conceptual, cambios estructurales y, además, se analizó la posible toxicidad de los distintos modelos finitos de grafeno. De estos, se seleccionaron al óxido de grafeno y al fluorografeno como posibles vehículos para el transporte de antioxidantes. En la segunda y tercera parte del proyecto se analizaron distintas propiedades de los antioxidantes endógenos y exógenos, para diseñar nuevos antioxidantes que puedan frenar el estrés oxidativo. Por lo que, se calcularon los descriptores para estimar la biodisponibilidad, se calculó el valor del pKa, la energía de solvatación, se estimó la toxicidad y mecanismos de reacción primarios como son la transferencia electrónica simple (SET) y la transferencia de átomos de hidrógeno (HAT); así como la inhibición de una enzima productora de radicales libres, xantina oxidasa. De este análisis se confirma que CAPE y CA son buenos antioxidantes. Finalmente, se diseñaron nanovectores conformados por los derivados de grafeno con los descriptores más adecuados (óxido de grafeno y fluorografeno), que responderán a estímulos redox para el transporte y liberación dirigida de los antioxidantes y, así, coadyuvar a a frenar el alto estrés oxidativo que origina múltiples enfermedades.

This research thesis presents a study within Density Functional Theory (DFT) of various finite models of graphene and some of its derivatives, endogenous melatonin and some analogs and exogenous antioxidants such as chicoric acid (CA), curcumin, and caffeic acid phenethyl ester (CAPE) to form nanovectors that help reduce oxidative stress. In the first part of the project, the change in different graphene finite models' chemical properties and some of their derivatives, such as graphene doped with boron (B), nitrogen (N), or phosphorus (P), graphane, fluorographene, graphyne, graphdiyne, and graphene oxide, were analyzed. For this purpose, we analyzed the global and local descriptors of the Conceptual DFT reactivity, structural changes, and the possible toxicity of the different graphene finite models. Graphene oxide and fluorographene were selected to be potential drug delivery vehicles for antioxidants transport. In the second and third part of this project, different endogenous and exogenous antioxidants were analyzed to design new antioxidants to stop oxidative stress. For this, chemical properties were studied through calculation of the global descriptors like, the value of pKa, solvation energy, toxicity, and the primary reaction mechanisms such as the simple electron transfer (SET) and hydrogen atom transfer (HAT); as well as the inhibition of a free radical-producing enzyme, xanthine oxidase. According to our results, CAPE and CA are good antioxidants. Finally, nanovectors made up of selected graphene derivatives (graphene oxide and fluorographene), were designed to respond to redox stimuli for the transport and targeted release of antioxidants. Our designed nanovectors are new potential systems, thus aiding to stop the high oxidative stress that causes multiple diseases.

Doctoral thesis

CGU- Doctorado en Química BIOLOGÍA Y QUÍMICA CIENCIAS TECNOLÓGICAS TECNOLOGÍA BIOQUÍMICA Grafeno – Derivados Índices de reactividad Química teórica y computacional DFT Conceptual (Teoría de Funcionales de la Densidad) Nanovectores Moléculas antioxidantes Graphene - Derivatives Reactivity indexes Theoretical and computational chemistry Conceptual DFT (Density Functional Theory) Nanovectors Antioxidant molecules

Densidade e qualidade ambiental o inevitável, o desejável e o possível

Denise Duarte (2012)

A pesar de las críticas, la ciudad moderna fue una solución a los problemas de finales del siglo XIX y gran parte del siglo XX, pero hoy se presentan otras circunstancias. Estamos nuevamente en un punto de inflexión y esta vez enfrentados a la escasez de recursos, cambio climático, entre otros problemas. En este contexto, dos fuerzas importantes que están conformando nuestras ciudades son: el crecimiento de la población y el aumento de las tasas de urbanización. Por diversas razones, una de las necesidades actuales de las aglomeraciones urbanas es una mayor densidad de ocupación, priorizando la ciudad existente, lo que ha provocado un gran debate. La ocupación urbana de mayor densidad es inevitable. La urbanización y alta densidad de ocupación son irreversibles. El modo de vida más denso continuará desarrollándose y en un futuro será la norma.

Though there is criticism, the modern city was a solution to the problems at the end of the 19th century and much of the 20th century, but today other circumstances arise. We are again at a turning point and this time faced with the scarcity of resources, change climate, among many other problems. In this context, two important forces that are shaping our cities, these are: the increase in the rates of urbanization and the growth of the population. For various reasons, one of the current needs of urban agglomerations is a higher density of occupation, giving priority to the existing city, which has caused a great debate. Higher density urban occupation is inevitable. Urbanization and high density of occupation are irreversible. The more dense way Universidad de São Paulo, Brasil of life will continue to develop and will be standard in the future.

Book part

Calidad ambiental. Sustainable development--Brazil. Population density--Brazil--Case studies. Urbanization--Brazil. Densidad de población. Urbanización. Política ambiental. HC190.E5 HUMANIDADES Y CIENCIAS DE LA CONDUCTA CIENCIAS DE LAS ARTES Y LAS LETRAS ARQUITECTURA URBANISMO