1,394 research outputs found

    Aplicación del modelo modergis en el uso sostenible en la dendroenergía y los biocombustibles para países en vía de desarrollo- caso Colombia.

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    Numerosos países en vía de desarrollo caso Colombia, contienen un enorme potencial de recursos en energías renovables como la dendroenergía incluidos los biocombustibles, pero no se utilizan en gran magnitud ni se han incorporado al Mix Energético Nacional debido a la falta de herramientas que las evalué e integre de manera armónico y con criterio sostenible. En tal sentido la Universidad Nacional de Colombia y el Centro de Investigaciones Energéticas Medioambientales y Tecnológicas - CIEMAT de España, han desarrollado conjuntamente una herramienta de planificación energética sostenible denominada - MODERGIS - que tiene como objeto la incorporación, evaluación y análisis de energías renovables con énfasis a la dendroenergía y los biocombustibles utilizando las técnicas de los Sistemas de Información Geográfica - SIG, como instrumento alternativo de planificación y uso sostenible ambiental, social, económico y cultural del uso del suelo. El modelo esta conformado por tres componentes: ENERDEM modelo de demanda- oferta de energía, ENERSIG: espacialización e integración de energías renovables mediante los Sistemas de Información Geográfica - SIG y ENERSOS modelo basado en métodos de análisis multiobjetivo tendientes a optimizar las dimensiones de la sostenibilidad de las fuentes energética, incorporando el análisis de ciclo de vida. Los resultados preliminares del modelo presentan 6.8 Millones de hectáreas factibles en el uso de la Dendroenergía, el cual significaría un potencial de 4400 MW instalables si se dedicara en la producción de energía eléctrica. En biocombustibles el Biodiesel de palma de aceite arroja un potencial de 1017 millones de barriles y 54 millones de barriles de etanol de caña de azúcar, el cual justificaría proporciones de abastecimiento interno con las mezclas de E10 y B5, quedando un gran potencial para interferir el mercado internacional, lo cual con la metodología de ModerGIS tiene incluido los criterios de sostenibilidad que son necesarios para ingresar a estos mercados.An essential element to reach sustainable development is an appropriate and reliable energy supply. This helps to eradicate poverty, improve human welfare, and to raise quality of life in the population. However, many regions in the world do not have a reliable supply, and its use exceeds economic limits, creating a dichotomy between growth and sustainability. World institutons such as United Nations and its organization UNESCO, have demonstrated that current energy production and consumption models are not sustainable in a medium term. Many countries, especially those that are in development such as Colombia, have a great potential of renewable energy resources that have not been used or incorporated into the energy mix due to the lack of tools to evaluate and to integrate them with a sustainability criteria. Then, “Universidad Nacional de Colombia” (Colombia) and “Centro de Investigaciones Energéticas Medioambientales y Tecnológicas – CIEMAT” (Spain) have jointly developed an integrated energy planning tool named MODERGIS. Its objective is to incorporate, evaluate and analyze renewable resources such as wood energy including biofuels. This model comprises three constitutive elements: an energy supply-demand model (ENERDEM), an integration and space definition of renewable energy through geographic information systems (ENERSIG), and a multi-objectiveanalysis to optimize sustainability dimensions of energy sources (ENERSOS). The current paper shows some of the preliminary results of this model, and discusses on the methodological issues faced during its development. Further and more expanded results are expected to be published in the near future

    Customer perceptions about family firms and their effects on customer behaviors

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    The current is an exploratory project exploring the associations and impressions evoked by the term “family-owned business” (FOBs) and how these impressions affect intentions to buy from a family firm. Four studies were conducted to assess the perceptions about family firms. Based on signaling theory and the theory of reason action, it was predicted that the family nature of firms would act as a signal that consumers will use to determine perceptions, attitudes towards family firms, and intentions to buy from family firms. Results indicate that, in general, participants had positive perceptions about organizational values and neutral perceptions about products and services offered by family firms. As suggested by the Theory of Reasoned Action, these perceptions affected attitudes and intentions towards FOBs. Implications for theory and practice are discussed

    Efecto del enriquecimiento con nutrientes en la degradación de clorpirifos, malatión y metil paratión

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    Con el fin de evaluar el efecto del enriquecimiento con nutrientes (una sal de fósforo o un fertilizante comercial con N, P y K) como alternativa para mejorar la capacidad de degradación de los microorganismos en una matriz sólida, contaminada con los pesticidas organofosforados: clorpirifos, malatión y metil paratión, se realizaron experimentos de cultivo bajo condiciones controladas de oscuridad, temperatura y humedad por 30 días. En todos los tratamientos hubo degradación de los pesticidas; sin embargo, en el tratamiento con fósforo los tiempos para degradar el clorpirifos y el metil paratión fueron mayores. La presencia de los pesticidas no generó efectos tóxicos detectables sobre la microflora en ninguno de los tratamientos evaluados. La actividad biológica de las matrices no presentó una relación directa con la capacidad de degradación. Abstract In order to evaluate the effect of inorganic nutrient addition (phosphorus or commercial fertilizer) over the microbial degradation capacity present in a solid matrix contaminated with chlorpyrifos, malathion and methyl parathion, microcosms assays were held under controlled conditions of light, moisture and temperature for 30 days. Results showed that even though three treatments microorganisms were able to degrade the three organophosphorus pesticides, microorganisms of phosphorus-enrichment treatment were less efficient to degrade Chlorpyrifos and Methyl Parathion than microorganisms of Fertilizer-enrichment treatment. It was not observed a direct relation between mineralization and microbial pesticides degradation capacity. The microbial activity was not affected by the presence of organophosphorus pesticides

    Prostaglandin E 2 production and viability of cells cultured in contact with freshly mixed endodontic materials

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73861/1/j.1365-2591.2006.01070.x.pd

    Productividad cianobacteriana, variaciones del carbono orgánico y facies de la Formación Indidura (Cenomaniano-Turoniano), noreste de México

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    Las rocas de edad Cenomaniano-Turoniano normalmente asignadas a la Formación de Indidura en México nororiental (Estado de Coahuila) contienen facies distintivas que son indicativas de una variabilidad espacial importante a través de la plataforma de carbonatos. Se han seleccionado tres secciones estratigráficas para probar si estas diferencias existen. La sección de Las Delicias (estratotipo) esta caracterizada por capas naranja claro de biocalciruditas (10-30 centímetros de espesor). Las estructuras internas primarias están ausentes. Los aloquímicos consisten esencialmente en asociaciones ricas en fósiles de equinodermos, pelecípodos, así como amonitas y foraminíferos planctónicos. El contenido de carbonato total (CaCO3) varía entre 48% y 94%, y el contenido de carbono total orgánico (TOC) entre 0,7% y 1,5%.La sección del Cañón La Casita, está al sureste de Las Delicias. Esta consiste en capas café claro amarillento de biocalcilutitas y lutitas laminadas verde oliva a grises con espesores de 3 a 30 cm. No se observa ninguna estructura interna deposicional; en las secciones delgadas se observa claramente abundante bioturbación. Los aloquímicos esencialmente son fragmentos esparcidos de foraminíferos planctónicos y radiolarios concentrados en madrigueras. El carbonato total (CaCo3) varía entre el 0,8% y 59,3%, mientras que el TOC varia entre el 0,17% y 5,8%. En contraste con estas sucesiones pobremente laminadas, en la Sierra de Parras, al sur de La Delicias y al oeste de la Casita, la sucesión se presenta como intercalaciones rítmicas de lutitas laminadas grisverdosas y negroparduzcas con espesores de 8 a 200 cm y biocalcilutitas margosas de 5 a 100 cm de espesor. Ambas facies exhiben estructuras internas similares organizadas en forma de laminillas duales paralelas “varvas” de < 3 mm de espesor, que contienen escasos foraminíferos planctónicos esparcidos en las laminillas oscuras. No se hay restos de epifauna, salvo esporádicos pelecípodos (Inocerámidos). El contenido de carbonato total (CaCO3) varía entre 43% y 78,3%, mientras que el contenido de TOC es relativamente alto con valores entre 7,3% y 24,3%, consistentemente superiores a 20%. La observación, de las laminillas presentes en las facies del área de Parras, muestra que sus diferencias composicionales están asociadas a la variabilidad en la abundancia de esferas microscópicas o “micro-oolitos.” Estas estructuras son interpretadas como de un posible origen cianobacteriano y se entienden como ciclos que representan eventos de florecimientos de cianobacterias, las cuales permanecieron dominantes a lo largo de la sucesión. Aún más, las lutitas laminadas y biocalcilutitas negras y ricas en TOC de la región de Parras documentan unas condiciones paleoceanográficas únicas, las cuales estaban caracterizadas por aguas oceánicas relativamente pobres en oxígeno.La distribución de la epifauna y las variaciones de carbón/carbonato en la región de Parras, sugieren que en los fondos de acumulación hubo fuertes eventos rítmicos de disoxia/anoxia. Esto contrasta claramente con los sedimentos de las áreas de Las Delicias y de La Casita, en las que se documentan condiciones del fondo diferentes, donde la epifauna bentónica y la fauna planctónica y nectónica pudieron proliferar. Asumiendo que estas facies son coetáneas, los análisis de microfacies y de TOC de estas rocas demuestran aún más las diferencias entre estas áreas

    Discrete but variable structure of animal societies leads to the false perception of a social continuum

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    Animal societies are typically divided into those in which reproduction within a group is monopolized by a single female versus those in which it is shared among multiple females. It remains controversial, however, whether these two forms of social structure represent distinct evolutionary outcomes or endpoints along a continuum of reproductive options. To address this issue and to determine whether vertebrates and insects exhibit the same patterns of variation in social structure, we examined the demographic and reproductive structures of 293 species of wasps, ants, birds and mammals. Using phylogenetically informed comparative analyses, we found strong evidence indicating that not all reproductive arrangements within social groups are viable in nature and that in societies with multiple reproductives, selection favours instead taxon-specific patterns of decrease in the proportion of breeders as a function of group size. These outcomes suggest that the selective routes to sociality differ depending upon whether monopolization of reproduction by one individual is possible and that variation within and among taxonomic groups may lead to the false perception of a continuum of social structures. Thus, the occurrence of very large societies may require either complete reproductive monopolization (monogyny/singular breeding) or the maintenance of a taxon-specific range of values for the proportional decrease in the number of breeders within a group (polygyny/plural breeding), both of which may reduce reproductive conflict among females

    Liquid culture for isolating microorganisms with potential to degrade methyl parathion from agricultural soils and organic waste.

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    The search for microorganisms with high capacity for pesticide degradation is a very interesting attempt to approach bioremediation strategies in order to prevent contamination. This study evaluates the potential of agricultural soils and solid organic waste cultures microbial isolation as a strategy for screening microorganisms with potential for Methyl parathion (MP) degradation. For the study, microbial consortia were recovered from the liquid fraction of suspension cultures of agricultural soils and solid organic waste. Then, the MP degradation ability and its toxic effect on microbial activity were determined during microbial incubations under laboratory controlled conditions. The results showed that it is not possible to recover the active microorganisms that have potential to degrade the MP from the agricultural soils. However, an active consortium that would degrade both MP and its degradation products was isolated from the organic solid waste

    Mode-Wise Entanglement of Gaussian States

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    We address the decomposition of a multi-mode pure Gaussian state with respect to a bi-partite division of the modes. For any such division the state can always be expressed as a product state involving entangled two-mode squeezed states and single mode local states at each side. The character of entanglement of the state can therefore be understood modewise; that is, a given mode on one side is entangled with only one corresponding mode of the other, and therefore the total bi-partite entanglement is the sum of the modewise entanglement. This decomposition is generally not applicable to all mixed Gaussian states. However, the result can be extended to a special family of "isotropic" states, characterized by a phase space covariance matrix with a completely degenerate symplectic spectrum.Comment: 4 pages, RevTex4. Replaced with revised version with reference added to a previous related paper. Minor typographical errors correcte

    Liquid culture for isolating microorganisms with potential to degrade methyl parathion from agricultural soils and organic waste.

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    The search for microorganisms with high capacity for pesticide degradation is a very interesting attempt to approach bioremediation strategies in order to prevent contamination. This study evaluates the potential of agricultural soils and solid organic waste cultures microbial isolation as a strategy for screening microorganisms with potential for Methyl parathion (MP) degradation. For the study, microbial consortia were recovered from the liquid fraction of suspension cultures of agricultural soils and solid organic waste. Then, the MP degradation ability and its toxic effect on microbial activity were determined during microbial incubations under laboratory controlled conditions. The results showed that it is not possible to recover the active microorganisms that have potential to degrade the MP from the agricultural soils. However, an active consortium that would degrade both MP and its degradation products was isolated from the organic solid waste

    Concrete with partial replacement of natural aggregate by PET aggregate—An exploratory study about the influence in the compressive strength

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    The expansion of cities contributed to the problems related to the accumulation of waste and lack of control over its management, there are still around 2400 dumps or uncontrolled landfills in Brazil. There is a large volume of polyethylene terephthalate (PET) improperly discarded. In turn, the construction industry has been looking for sustainable ways to produce concrete. This work deals with the analysis of the replacement of PET as a fine aggregate in concrete in the proportions of 5% and 15%. PET particles pass more than 75% in the 2.36 mm opening sieve and have more than 99% of their particle size retained in the 0.15 mm opening sieve. Concrete properties, compressive strength, tensile strength, water absorption and void ratio were evaluated and compared with the reference mix. In total, 45 specimens cast in concrete were used to complete the experiment. The results obtained showed that mixture compositions that incorporate PET as fine aggregates decrease compressive and tensile strength, increase water absorption and void index. The results obtained showed that blending compositions that incorporate PET as fine aggregates decrease compressive strength in about 14%, decrease tensile strength in about 7–11%, increased the void ratio in almost 20% and increased the water absorption in about 30%.info:eu-repo/semantics/publishedVersio
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