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Search Results: 1 - 10 of 449996 matches for " Carlos M Duarte "
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Expansion of vegetated coastal ecosystems in the future Arctic
Dorte Krause-Jensen,Carlos M. Duarte
Frontiers in Marine Science , 2014, DOI: 10.3389/fmars.2014.00077
Abstract: Warming occurs particularly fast in the Arctic and exerts profound effects on arctic ecosystems. Sea ice-associated ecosystems are projected to decline but reduced arctic sea ice cover also increases the solar radiation reaching the coastal seafloors with the potential for expansion of vegetated habitats, i.e. kelp forests and seagrass meadows. These habitats support key ecosystem functions, some of which may mitigate effects of climate change. Therefore, the likely expansion of vegetated coastal habitats in the Arctic will generate new productive ecosystems, offer habitat for a number of invertebrate and vertebrate species, including provision of refugia for calcifiers from possible threats from ocean acidification, contribute to enhance CO2 sequestration and protect the shoreline from erosion. The development of models allowing quantitative forecasts of the future of vegetated arctic ecosystems requires that key hypotheses underlying such forecasts be tested. Here we propose a set of three key testable hypotheses along with a research agenda for testing them using a broad diversity of approaches, including analyses of paleo-records, space for-time substitutions and experimental studies. The research agenda proposed would provide a solid underpinning to guide forecasts on the spread of marine macrophytes onto the Arctic with climate change and contribute to balance our understanding of climate change impacts on the arctic ecosystem through a focus on the role of engineering species. Anticipating these changes in ecosystem structure and function is key to develop managerial strategies to maximize these ecosystem services in a future warmer Arctic.
CARACTERIZACIóN FISICOQUíMICA DE PECIOLOS DEL PANGUE (Gunnera tinctoria)
Petzold M,Guillermo; Catril C,Gonzalo; Duarte D,Carlos;
Revista chilena de nutrición , 2006, DOI: 10.4067/S0717-75182006000500010
Abstract: the petioles of pangue (gunnera tinctoria) are foods with a very pleasant acid flavor and constitute an important non-wood forests product (nwfp) of chile which may be an alternative for the formulation of new food products. the objectives of this work were to determine its proximal chemical composition, to establish its energy contribution and to define some of their physiochemical and biochemical properties. the content of proteins, lipids, moisture, fiber, ashes, carbohydrates, ascorbic acid, soluble solids, and water activity were determined. the activities of the enzymes peroxidase and poliphenoloxidase were also measured. the results show that the commodity possesses a high content of moisture and water activity, and a reduced contribution of energy and ascorbic acid. the petioles present an intense green color in the nearby portion of rhizome. they have a reduced ph that permits to classify them as an acid food. the results give an orientation on the possible strategies of processing of this vegetable to obtain food products with a shelf life that permit their commercialization
CARACTERIZACIóN FISICOQUíMICA DE PECIOLOS DEL PANGUE (Gunnera tinctoria) PHYSICOCHEMICAL CHARACTERIZATION OF PETIOLES OF PANGUE (Gunnera tinctoria)
Guillermo Petzold M,Gonzalo Catril C,Carlos Duarte D
Revista Chilena de Nutricíon , 2006,
Abstract: Los pecíolos del pangue (Gunnera tinctoria) son comestibles con un sabor ácido muy agradable y constituyen un importante producto forestal no maderable (PFNM) de Chile. Sin embargo, no existen antecedentes sobre las características de este vegetal que permitan un uso industrial alternativo que puede ser la formulación de nuevos productos alimentarios. Los objetivos de este trabajo fueron determinar la composición químico proximal, el aporte energético y algunas propiedades fisicoquímicas y bioquímicas de los pecíolos del pangue. Se determinó el contenido de proteínas, lípidos, humedad, fibra, cenizas, carbohidratos por diferencia, pH, ácido ascórbico, actividad de agua, sólidos solubles, color y enzimas peroxidasa y polifenoloxidasa. Los resultados muestran que la materia prima posee un elevado contenido de humedad y actividad de agua, un reducido aporte energético y trazas de ácido ascórbico. El color de los pecíolos presenta una coloración verde más intensa en la porción cercana al rizoma. Asimismo, posee un pH reducido que permite clasificarlo como un alimento ácido y presenta actividad de la enzima peroxidasa. Los resultados entregan una orientación sobre las posibles estrategias de procesamiento de este vegetal para obtener productos alimentarios con una vida útil que permita su comercialización The petioles of pangue (Gunnera tinctoria) are foods with a very pleasant acid flavor and constitute an important non-wood forests product (NWFP) of Chile which may be an alternative for the formulation of new food products. The objectives of this work were to determine its proximal chemical composition, to establish its energy contribution and to define some of their physiochemical and biochemical properties. The content of proteins, lipids, moisture, fiber, ashes, carbohydrates, ascorbic acid, soluble solids, and water activity were determined. The activities of the enzymes peroxidase and poliphenoloxidase were also measured. The results show that the commodity possesses a high content of moisture and water activity, and a reduced contribution of energy and ascorbic acid. The petioles present an intense green color in the nearby portion of rhizome. They have a reduced pH that permits to classify them as an acid food. The results give an orientation on the possible strategies of processing of this vegetable to obtain food products with a shelf life that permit their commercialization
Linfoma cerebral en paciente postrasplante renal Primary brain lymphoma in a patient after renal transplantation
Carlos Arteaga,Mónica Duarte,Hernán Bayona,Rafael Andrade
Acta Medica Colombiana , 2009,
Abstract: El linfoma primario del sistema nervioso central (LPSNC) ha tenido un aumento en la incidencia en los últimos 40 a os asociado con estados de inmunosupresión, principalmente en pacientes infectados con el virus de inmunodeficiencia humana (VIH) y con trasplante de órganos. La tumorogénesis se relaciona con el virus de Epstein Barr (VEB). El inmunofenotipo más frecuente es el linfoma de células B. Las manifestaciones clínicas son dependientes de la localización de la masa tumoral, principalmente trastornos del comportamiento y síndrome de hipertensión endocraneana. El diagnóstico diferencial etiológico se hace con procesos infecciosos, enfermedad cerebrovascular (ECV), tumores primarios gliales del sistema nervioso central y metástasis cerebrales. Al diagnóstico se llega a través de imágenes diagnósticas principalmente resonancia magnética (RM ) cerebral y con estudio histopatológico. Es importante descartar infección por VIH al hacerse diagnóstico de LPSNC. En esta revisión reportamos un linfoma primario del SNC en una paciente con antecedente de trasplante renal por enfermedad poliquística ocho a os antes. The incidence of primary central nervous system lymphoma (PCNSL) has increased during the past 40 years. This has been associated with immunodeficiency, mainly in patients infected with the human immunodeficiency virus (HIV) and in transplant patients. Tumor genesis is related with the Epstein-Barr virus (EBV). The most frequent PCNSL immunophenotype is B-cell lymphoma. Clinical manifestations depend on tumor localization, and are usually behavior dysfunctions and intracranial hypertension syndrome. Differential diagnosis must take into consideration infectious processes, stroke, primary brain tumors, and metastases. The diagnosis of PCNSL requires brain MRI and brain biopsy. It is important to assess HIV infection when diagnosing PCNSL. This review reports a case of primary brain lymphoma in a patient who underwent renal transplantation due to polycystic kidney disease 8 years before.
CHANGES IN THE C, N AND P CYCLES BY THE PREDICTED SALPS-KRILL SHIFT IN THE SOUTHERN OCEAN.
Miquel Alcaraz,Rodrigo Almeda,Carlos M. Duarte,Sebastien Lasternas
Frontiers in Marine Science , 2014, DOI: 10.3389/fmars.2014.00045
Abstract: The metabolic carbon requirements and excretion rates of three major zooplankton groups in the Southern Ocean were studied in February 2009. The research was conducted in the framework of the ATOS research project as part of the Spanish contribution to the International Polar Year. The objective was to ascertain the possible consequences of the predicted zooplankton shift from krill to salps in the Southern Ocean for the cycling of biogenic carbon and the concentration and stoichiometry of dissolved inorganic nutrients. The carbon respiratory demands and NH4-N and PO4-P excretion rates of < 5 mm size copepods, krill and salps were estimated by incubation experiments. The carbon-specific metabolic rates and N:P metabolic quotients of salps were higher than those of krill (furcilia spp. and adults) and copepods, and as expected there was a significant negative relation between average individual zooplankton biomass and their metabolic rates, each metabolic process showing a particular response that lead to different metabolic N:P ratios. The predicted change from krill to salps in the Southern Ocean would encompass not only the substitution of a pivotal group for Antarctic food webs (krill) by one with an indifferent trophic role (salps). In a zooplankton community dominated by salps the respiratory carbon demand by zooplankton will significantly increase, and therefore the proportion of primary production that should be allocated to compensate for the global respiratory C-losses of zooplankton. At the same time, the higher production by salps of larger, faster sinking fecal pellets will increase the sequestration rate of biogenic carbon. Similarly, the higher N and P excretion rates of zooplankton and the changes in the N:P stoichiometry of the metabolic products will modify the concentration and proportion of N and P in the nutrient pool, inducing quantitative and qualitative changes on primary producers that will translate to the whole Southern Ocean ecosystem.
Dissolved organic carbon fluxes by seagrass meadows and macroalgal beds
Cristina Barron,Eugenia T. Apostolaki,Carlos M. Duarte
Frontiers in Marine Science , 2014, DOI: 10.3389/fmars.2014.00042
Abstract: Estimates of dissolved organic carbon (DOC) release by marine macrophyte communities (seagrass meadows and macroalgal beds) based on in situ benthic chambers from published and unpublished are compiled in this study. The effect of temperature and light availability on DOC release by macrophyte communities was examined. Almost 85 % of the seagrass communities and all of macroalgal communities examined acted as net sources of DOC. Net DOC fluxes in seagrass communities increase positively with water temperature. In macroalgal communities net DOC fluxes under light exceeded those under dark condition, however, this trend was weaker in seagrass communities. Shading of a mixed seagrass meadow in The Philippines led to a significant reduction on the net DOC release when shading was maintained for 6 days compared to only 2 days of shading. Net DOC fluxes increased with increasing community respiration, but were independent of primary production or net community production. The estimated global net DOC flux, and hence export, from marine macrophytes is about 0.158 ± 0.055 Pg C yr-1 or 0.175 ± 0.056 Pg C yr-1 depending on the global extent of seagrass meadows considered.
Capitalismo, etnicidad y globalizacion: el caso andino
Duarte,Carlos;
Análisis Político , 2006,
Abstract: during the last the 15 years the phenomena of ethnic mobilization, have taken an unusual importance within the globalisation. the objective of this paper will be to present the general cadre in which these phenomena follow one another, regarding the affinities and specificities of these processes in three countries of the andean area ( colombia, ecuador and bolivia ). the intention will be to show how the indigenous policies of the andean states correspond with the processes of expansion and capitalist accumulation. by this way, we set out to locate the impacts produced by the neoliberal reforms imposed to the andean states, within the present phenomena of "globalization" and "location". finally we will try to suggest some analyses that demonstrate the relation between the revitalisation of the indigenous organization, the production of the expert knowledge and the famous "paradoxes of the ethnicity ".
IMPLEMENTACIóN Y CRISIS DEL ACTUAL SISTEMA DE GOBERNABILIDAD MINERA EN COLOMBIA: EL MODELO DE ENCLAVE EXPORTADOR IMPLEMENTATION AND CRISIS OF THE CURRENT MINING GOVERNANCE SYSTEM IN COLOMBIA: THE MODEL OF EXPORT ENCLAVE
Carlos Duarte
Análisis Político , 2012,
Abstract: Este trabajo se sustenta en una revisión a las transformaciones contemporáneas de la legislación colombiana, buscando caracterizar cual es el modelo de gobernabilidad minera a partir de la Constitución de 1991. Para tal fin se desarrolla un ejercicio comparativo entre el sistema legislativo inmediatamente precedente (el Código minero de 1988), continuando con la legislación que gravita alrededor de la Ley 685 (Código minero vigente), para finalizar con los discusiones jurídicas y sociales que llevarían a declarar inexequible la última de las reformas legislativas (Ley 1382 del 2010). Este ejercicio busca delinear la administración de los recursos mineros bajo la tensión entre las políticas de apertura económica y los derechos sociales consagrados en la nueva constitución. A modo de conclusión se problematiza el actual sistema de gobernanza minera frente a anteriores modelos de gobernanza minera implementados en el país. Luego, se realiza un paralelo entre la legislación colombiana y los principales elementos que vienen transformándose en la legislación minera chilena. Finalmente, se plantea hasta que punto una administración del subsuelo que busca a toda costa ofrecer las mejores garantías para que la explotación minera se realice de acuerdo a los intereses multinacionales, puede convertirse en herramienta de despojo hacia la pe6que a minería y numerosos territorios habitados por poblaciones étnicas This work is based on a review of contemporary transformations of Colombian law, seeking to characterize the mining governance model from 1991 Constitution until now. To this end, a comparison is developed between the immediately preceding legal system (the Mining Code of 1988), followed by the Law 685 (current Mining Code), to arrive at the legal and social discussions that would lead to declare unconstitutional the latest legislative changes (Act 1382 of 2010). This exercise intends to delineate the management of mineral resources under the tension between policies of economic liberalization and social rights recognized in the new constitution. As a conclusion, it questions the current governance system compared to previous mining governance models implemented in the country. Then, a parallel between the Colombian legislation and the main elements that are changing in the Chilean mining legislation is done. Then, it analyzes how and administration that seeks, at all cost, to provide the best guarantee that the mining is done in accordance with multinational interests, can become an accessory of dispossession against the small miners in territories inhabite
Capitalismo, etnicidad y globalizacion: el caso andino Capitalism, etnicidad and globalizacion: The Andean case
Carlos Duarte
Análisis Político , 2006,
Abstract: Durante los últimos 15 a os los fenómenos de reivindicación étnica y de movilización social desde los espacios locales, han tomado un auge inusitado en el marco de la globalización. El objetivo de este escrito será presentar el encuadramiento general en el que se suceden estos fenómenos, fijando la mirada en las afinidades y especificidades de estos procesos en tres países del área andina (Colombia, Ecuador y Bolivia). La intención será mostrar hasta que punto las políticas indigenistas de los estados nación andinos corresponden con los procesos de expansión y acumulación capitalista. De esta manera, nos proponemos situar los impactos producidos por las reformas neoliberales al antiguo modelo de estado-nación, dentro de los actuales fenómenos de "globalización" y "localización". Finalmente se pretenderá sugerir algunas líneas de análisis que evidencien la relación entre la revitalización de la organización indígena, la producción del conocimiento experto y las famosas "paradojas de la etnicidad". During the last the 15 years the phenomena of ethnic mobilization, have taken an unusual importance within the globalisation. The objective of this paper will be to present the general cadre in which these phenomena follow one another, regarding the affinities and specificities of these processes in three countries of the Andean area ( Colombia, Ecuador and Bolivia ). The intention will be to show how the indigenous policies of the Andean states correspond with the processes of expansion and capitalist accumulation. By this way, we set out to locate the impacts produced by the neoliberal reforms imposed to the Andean states, within the present phenomena of "globalization" and "location". Finally we will try to suggest some analyses that demonstrate the relation between the revitalisation of the indigenous organization, the production of the expert knowledge and the famous "paradoxes of the ethnicity ".
Scaling properties of protein family phylogenies
Alejandro Herrada, Víctor M Eguíluz, Emilio Hernández-García, Carlos M Duarte
BMC Evolutionary Biology , 2011, DOI: 10.1186/1471-2148-11-155
Abstract: The comparative analysis between protein and species phylogenies shows that both sets of phylogenies share a remarkably similar scaling behavior, suggesting the universality of branching rules and of the evolutionary processes that drive biological diversification from gene to species level. In order to explain such generality, we propose a simple model which allows us to estimate the proportion of evolvability/robustness needed to approximate the scaling behavior observed in the phylogenies, highlighting the relevance of the robustness of a biological system (species or protein) in the scaling properties of the phylogenetic trees.The invariance of the scaling properties at levels spanning from genes to species suggests that rules that govern the incapability of a biological system to diversify are equally relevant both at the gene and at the species level.During the last century, an important effort has been devoted to the understanding of diversification patterns and processes in terms of branching evolutionary trees [1-7]. Tempo and mode of genetic change, and their connections with tempo and mode of speciation is an important issue in this context. In that sense, we address the question of whether similar forces act across the gene level and species-level evolution [8-10], through a comparative analysis of the topological behavior of protein and species phylogenies.Previous analyses of the topological properties of phylogenies have revealed universal patterns of phylogenetic differentiation [3,6,7,11,12]. This means that the impact of evolutionary forces shaping the diversity of life on Earth on the shape of phylogenetic trees is, at least to the level of detail captured by the descriptors used, similar across a broad range of scales, from macro-evolution to speciation and population differentiation, and across diverse organisms such as eukaryotes, eubacteria, archaea or viruses, thereby. This together with the fact that evolutionary forces work at molecular lev
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