Biblioteca Digital

The fine and ultra fine size of diesel particulate mater (DPM) are of great health concern and significantly contribute to the overall cancer risk. In addition, diesel particles may contribute a warming effect on the planet's climate. The composition of these particles is composed principally of elemental carbon (EC) with adsorbed organic compounds, sulfate, nitrate, ammonia, metals, and other trace elements. The purpose of this study was to depict the seasonality and modeling of particulate matter in the Southeastern US produced by the diesel fueled sources (DFSs). The modeling results came from four one-month cases including March, June, September, and December to represent different seasons in 2003 by linking Models-3/CMAQ and SMOKE. The 1999 National Emissions Inventory Version 3 (NEI99) was used in this analysis for point, area, and non-road sources, whereas the National Mobile Inventory Model (NMIM) was used to create the on-road emissions. Three urban areas, Atlanta, Birmingham, and Nashville were selected to analyze the DPM emissions and concentrations. Even though the model performance was not very strong, it could be considered satisfactory to conduct seasonal distribution analysis for DPM. Important hourly DPM seasonality was observed in each city...

In this paper I intend to show the difficulties of sustaining Raz's argument in support of collective rights in the case of multicultural societies. This is in contrast to the argument of this author with J. Griffin. I conclude that although there are communal property, in the case of multicultural societies the possibility that these act as an agency makes it very difficult to agree on them, and in the event of this agreement, the result can not be called «law» according to the theory of law upheld by Joseph Raz.

This study characterizes the spatial and temporal distribution of chlorophyll a (Chl a) and sea surface temperature (SST) in the Interior Sea of Chiloe in Chile at a moderate spatial resolution using SeaWiFS and MODIS-Aqua time series data from the Goddard Earth Science (GES) Data and Information Services Center (DISC) imported into the GES DISC Interactive Online Visualization and Analysis System ('Giovanni'). The Interior Sea of Chiloe is home to Chile's salmon farming industry, the world's second largest salmonid producer. This study undertakes the characterization of the main patterns of spatial and temporal variability of Chl a and SST in the Interior Sea of Chiloe using a continuous set of time series ocean colour and SST data. Both Chl a and SST exhibit a marked spatial and temporal distribution, with values being significantly higher in the northern area (41.4-42.7°S; total area 41.4-43.5°S) and during the spring-summer period. Peak Chl a concentrations tend to occur in a temporal interval from October to April (austral spring-austral autumn), whereas monthly averaged peak SST values occur consistently in the month of February (austral summer). Chl a concentrations exhibit strong interannual variations, with monthly averaged peak Chl a concentrations experiencing a twofold increase between the year with the lowest and highest Chl a peak concentration in the time series. Results suggest that at the present scale of analysis two spatial domains can be distinguished...

Using cluster analysis this study investigated the characteristics of learning strategies learners use in online courses with one-on-one mentoring. Three distinct approaches were identified: "Mastery oriented", "Task focused" and "Minimalist in effort". Despite the widespread concern that students will have difficulty managing their time in online courses with high level of student freedom, this study found that the vast majority of learners were very effective in their learning strategies. The findings speak well for the potential of distance education environments to provide high quality self-paced learning, accommodating different learning strategies, which is difficult to do in group-paced courses. We further explored how these approaches relate to and interact with, participants' background and their levels of satisfaction and self reported learning.

Life histories and population dynamics of two populations of Musculium argentinum, one inhabiting a fluvial environment and the other a lacustrine one, are compared. Musculium argentinum is oviparous, iteroparous, and sequential incubator, reproducing throughout the year. The life cycle pattern of the fluvial population, unlike the lacustrine one, is characterized by seasonal reproductive variations, more marked in spring and summer, higher fertility and population reproductive productivity (potential recruitment), higher number of marsupial sacs per hemibranch, and smaller size of first reproduction. The content of organic matter and water flow would be the main factors determining the higher population density observed in the fluvial population.

1. A fundamental goal of ecological network research is to understand how the complexity observed in nature can persist and how this affects ecosystem functioning. This is essential for us to be able to predict, and eventually mitigate, the consequences of increasing environmental perturbations such as habitat loss, climate change, and invasions of exotic species. 2. Ecological networks can be subdivided into three broad types: 'traditional' food webs, mutualistic networks and host-parasitoid networks. There is a recent trend towards cross-comparisons among network types and also to take a more mechanistic, as opposed to phenomenological, perspective. For example, analysis of network configurations, such as compartments, allows us to explore the role of co-evolution in structuring mutualistic networks and host-parasitoid networks, and of body size in food webs. 3. Research into ecological networks has recently undergone a renaissance, leading to the production of a new catalogue of evermore complete, taxonomically resolved, and quantitative data. Novel topological patterns have been unearthed and it is increasingly evident that it is the distribution of interaction strengths and the configuration of complexity, rather than just its magnitude...

Se entregan antecedentes que establecen que Diplodon patagonicus (D'Orbigny 1835) señalado como especie presente en la región Neo tropica-Patagonia por Graf & Cummins (2007) corresponde aDiplodon chilensis patagonicus (D'Orbigny 1846) (sensu Haas 1969).

The effect of climate on dairy and beef cattle is variable and complex because it affects the environment in which the animals are raised and reproduced. Its influence on animal welfare and production have been recognized and studied since 1950's. Climate affects livestock directly and indirectly, since it modifies the quality and/or quantity of food available, the requirements of water and energy, and the amount of energy consumed and the use of it. The animals cope with these adverse conditions of climate by altering physiological and behavioral mechanisms in order to maintain their body temperature within a normal range. As a result it is possible to observe changes in the food intake, behavior and productivity. These changes are magnified under extreme conditions of heat or cold, implying drastic reductions in the indices of production, such as average daily gain and daily milk production. Most of the research conducted in this area has been done mainly in controlled environmental chambers, with emphasis on the animal response and its productivity. Currently, the major scientific focus is on the development of thermal stress indices as practical tools for cattle handling under unfavorable environmental conditions. The objectives of this review are to describe and discuss the most important climatic factors affecting cattle performance as well as the major mitigation alternatives. It also presents a brief overview of the research carried out in Chile and possible lines of research in this field.; El efecto del clima en el ganado bovino es variable y complejo...

The aim of the present study was to experimentaly evaluate the capability of the freshwater mussel Diplodon chilensis as a potential depurator of residual waters in fish farming. With this purpose, the present study was carried out at the fish farm of the School of Aquaculture of the Catholic University- Temuco, Chile (38°46'S; 72°38'W). The experimental design consisted of 12 poly vinyl chloride trays of 50x20x20cm corresponding to 3 treatments with 3 replicates each treatment and their respective controls. Each tray contained sterilized sand substratum and running water from a trout feeding tank. The treatments 1, 2, 3 contained 15, 30 and 60 mussels respectively, while the control trays contained no mussels. The growth tank contained 5,2k/m3 of Oncorhynchus mykiss. The trouts were fed daily with 37g of fish food during the time of the experiment duration. At time 0 the wet weight and length of each mussel was measured to determine the physiological state of the specimens through the Condition index. At the onset of the experiment it was determined the mortality and the Condition index of each individual. Also water samples from each tray corresponding to the 3 treatments, their respective replicates and controls were taken at time 0...

The beekeeping in Chile has been especially important for the small and medium agriculture due to the several products that can be obtained from the explotation. One of the major problems is the incidence of diseases and parasites, being the acarus ectoparasite Varroa destructor Anderson & Trueman one of the main pathologies because of its difficult control since it's reproduced in brood capped cells, decreasing the population of the colony and in strong infestations making them disappear completely; also by using chemical products for its control, which are not used correctly, producing resistance and leaving residues in the bee products. In order to change this situation it is necessary to find new control alternatives such as genetic resistance through hygienic behavior. The hygienic behavior related to the infestation level of Varroa destructor is analyzed in this work. Twenty one honeybee colonies were involved in this study, which were evaluated from October to December 2005. The percentage of hygienic behavior of each colony was determined through the pin-killed test. Samples to carry out the diagnoses of varroa were also taken. The results showed a low and heterogeneous level of hygienic behavior, where the values fluctuated in the colonies in average from 20% to 80% (2 colonies). The non-existence of correlation was also shown. The evaluated parameters showed an infestation average of 4.5% in adult bee; 7% in worker brood and 31% in drone brood.; La apicultura en Chile ha sido importante sobre todo para la pequeña y mediana agricultura...

Mobile sources are among the largest contributors of NOx in the Great Smoky Mountains National Park region (GSMNP). In 2001, these sources contributed 45% of NOx emissions. From 1990 to 2001, the growth of vehicle miles traveled (VMT) increased 60% and 55% in neighboring Sevier and Blount counties respectively. These emissions combined with the high volatile organic compounds (VOC) emissions in the Southeast area have caused the ozone ground level concentration to be as high as some major metropolitan areas in the summer season. In 2001, the maximum 8-hr ozone concentration inside the park was 103 parts per billion. In response to high ozone levels in other areas, federal, state, and local governments are promoting the use of alternative, clean, and reformulated fuel vehicles as a means to improve local air pollution. One of these fuels is compressed natural gas (CNG). The purpose of this project was to use USEPA's CMAQ system in order to model the air quality and compare the ozone ground level formation in the GSMNP from light duty vehicles (LDVs) operating with 100% CNG within 100 miles around GSMNP. A severe southeast ozone episode between August and September 1999 was used as a reference and 2004 was used as a future case. Results showed that LDVs fueled with 100% CNG in the domain could reduce ozone level by 10% and 8% for 1-hr and 8-hr ozone formation respectively in the GSMNP on the modeled time period. Scavenging occurred around the GSMNP in the morning time during the selected episode.

A la fecha en Chile no existen estadísticas ni estudios sobre el uso (o abuso) de implantes anabólicos, estimándose que al menos el 50% de la carne que se produce en nuestro país proviene de animales que han recibido algún tipo de agente anabolizante.

Cambio climático, conciencia medioambiental, creciente demanda de alimentos. ¿Cómo afectará este escenario a la producción ganadera futura? A continuación, algunas señales para entender las transformaciones y prepararnos para las exigencias que se vienen.

Las proyecciones de diversos organismos indican que en el futuro la carne bovina será un producto “premium” debido a su creciente demanda, a la dificultad para producirla y al costo económico y ambiental en comparación a otras fuentes de proteína de origen animal. Chile se encuentra en un momento crucial, en el que deben conjugarse una serie de voluntades para lograr la consolidación necesaria de la industria en todos sus niveles.

Muchas de las pérdidas y ganancias que se obtienen en ganadería se explican por la gestión que se realiza al interior del predio. A continuación exponemos un estudio de caso con objeto de ejemplificar el impacto que tienen diversos factores en el negocio criancero.

Talcahuano and Hualpén counties are one of the most highly industrial-polluted coastal zones in Chile, overhanging the iron foundry industry, coal burning power plants, chemical industry, and petroleum refinery, etc. The relationship between air pollution from PM2.5 measured at the Libertad monitoring station and health effects as the daily number of deaths and hospital admissions, for specific cardiovascular and respiratory diseases were studied. The results were compared with a health perception survey applied to the local population during spring 2008. Significant statistical associations were found between daily mortality and morbidity in Talcahuano-Hualpén area for cardiovascular and respiratory diseases and daily PM2.5 concentration, coinciding with the health perception of the inhabitants from these counties. The results suggest that point sources may be responsible for increased mortality in that industrial area. This has an important implication in relation with the size and chemical composition of the particles, but also for monitoring and control strategies. This is an abstract of a paper presented at the 103rd AWMA Annual Conference and Exhibition (Alberta, Canada 6/22-25/2010).

Box-Jenkins Time Series (ARIMA) and the multivariate linear models (MLM) have been important and popular linear tools in air quality forecasting during the past decade for urban areas. On the other hand, artificial neural networks (ANN) recently have been used successfully as a nonlinear tool in several research studies of pollution forecasting. A hybrid model that combines both ARIMA and ANN tools was proposed to improve the unique capabilities of ARIMA and ANN tools in linear and non linear modeling on particulate matter forecasting. To examine the effectiveness of the proposed hybrid model over real particulate matter data, the time series of PM10 and meteorological data observed in ambient air during 2000-2006 at a site in Temuco, Chile, was used In 2005, this city was declared a non-attainment area for PM10, whose pollution is the result of a great economic growth, a fast urban expansion, woodstoves, industrial sources, and a strong diesel vehicles growth. Experimental results with meteorological and PM10 data sets indicated that the hybrid model can be an effective tool to improve the forecasting accuracy obtained by either of the models used separately, and compared with a statistical multivariate linear regression. This is an abstract of a paper presented at the 100th Annual Conference and Exhibition of the Air and Waste Management Association 2007 (Pittsburgh...

Air toxics concentrations and health effects that come from different sources emission scenarios by linking Models-3/CMAQ and cancer risk assessment were predicted. The year 1999 was used to emissions inventory and the year 2003 for meteorological data and modeling performance. To demonstrate the system's effectiveness, this study was performed on priority mobile sources air toxics; benzene, 1,3-butadiene, formaldehyde, acetaldehyde, and diesel particulate matter (DPM). The analysis was applied mainly to Nashville in the Southeastern US. Ten emissions scenarios were selected to compare the principal results. DPM posed a cancer risk that was 4.2 times higher than the combined total cancer risk from all other four air toxics. Those high cancer risk levels were due mainly to non-road sources (57.9%). For the on-road diesel fueled sources, the principal reductions were due to the DPM generated by heavy duty diesel vehicles. The main on-road reductions were due to the air toxics generated by gasoline light duty vehicles, principally benzene and 1,3-butadiene. Reducing ambient DPM concentrations would lead to improvement in human health more than other air toxics, indicating that better technologies and regulations must be applied to the mobile diesel engines...

The particulate matter pollution, induced mainly by the domiciliary wood heating, vehicular traffic, and industrial activity, has become the main source of concern of urban air quality in cities of colder climates. The city of Temuco, 800 km to the south of Santiago, Chile, suffers from severe wood smoke particulate pollution events. It is estimated that 87% of PM10 winter emissions originate from residential wood combustion. The relative risk estimations in Temuco were higher than those estimated in Santiago for respiratory mortality and for cardiovascular mortality. The main air pollution sources in Temuco are the residential wood stoves and wood cook stoves, while in Santiago are the diesel from mobile sources. The particles size distribution is different in Temuco and Santiago also. In winter season, the PM2.5 presents a higher proportion of the total PM10 in Temuco than in Santiago. These situations could explain the generation of higher toxicity over the exposed population in Temuco than that from Santiago, because finer particles penetrate more deeply in the respiratory system, even entering to the bloodstream and transported to other organs, where the PAH and other air toxics could cause toxic effects. Even though the study focused on PM10...