1,026 research outputs found

    Diversidad de mariposas (Lepidoptera, Papilionoidea) y su relación con el paisaje de alta montaña en los Andes nororientales de Colombia

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    Diversitat de papallones (Lepidoptera, Papilionoidea) i la seva relació amb el paisatge d’alta muntanya als Andes nord-orientals de Colòmbia La regió andina es caracteritza per acollir una gran varietat d’ecosistemes entre els quals es compten les característiques zones d’alta muntanya, que mostren processos de transformació del sòl accelerats que han convertit els boscos natius en zones agrícoles i ramaderes, la qual cosa ha ocasionant un declivi de la diversitat biològica regional. L’ús d’indicadors de diversitat és adequat per avaluar els canvis en els paisatges d’alta muntanya i les papallones són un dels grups més importants per determinar els canvis que es produeixen en els diferents tipus d’ambients. A l’àrea d’estudi es van establir dotze punts de mostreig als complexos d’erms d’Almorzadero, Santurbán i Tamá de la regió nord-oriental de Colòmbia. Durant la fase de mostreig es van practicar captures d’individus adults de papallones en transsectes de 100 x 4 m en un gradient altitudinal de 500 m. Es van registrar 69 espècies, pertanyents a cinc famílies. Els valors de diversitat de la comunitat de papallones diürnes van variar a les diferents cobertures vegetals associades a cada transsecte. Així, les àrees amb cobertura vegetal conservada (per exemple, bosc dens, arbustos i matolls i erm i suberm) van presentar els valors més alts de diversitat, mentre que les zones amb cobertura alterada (per exemple, bosc fragmentat, pastures i àrees agrícoles) van presentar els valors de diversitat més baixos. Les anàlisis d’estructura de comunitats evidencien que les espècies de papallones endèmiques estan associades a àrees fragmentades a les zones d’alta muntanya. Aquest estudi és el primer del seu tipus que estableix canvis en la diversitat de les papallones en zones d’alta muntanya del nord-est de Colòmbia i s’ha fet amb el propòsit de generar estratègies de conservació en llocs que presenten un alt grau d’endemisme i diversitat.Diversity of butterflies (Lepidoptera, Papilionoidea) and their relationship with the highlands’ landscape in the northeastern Andes of Colombia The Andean region harbors a great variety of ecosystems, including the characteristic high mountain zones. The biological diversity in these zones, however, is declining as the result of changes in land use, particularly the introduction of agriculture and cattle ranching. Changes in the high mountain landscape can be appropriately monitored using diversity indicators such as butterflies, one of the most important indicator species. We chose twelve sampling points in the paramo (high altitude moor) complexes Almorzadero, Santurbán and El Tamá, located in the northeastern region of Colombia to collect adult butterflies within transects of 100 x 4 m, along an altitudinal gradient of 500 m. We recorded 69 species, from five families. Diversity values of the diurnal butterfly communities varied among  the different areas of vegetation coverage associated with each transect. Conserved vegetation coverage (i.e. dense forest, scrublands and scrublands, and paramo and subparamo) showed the highest values of diversity, while  perturbed coverage (i.e. fragmented forests, pastures and agriculture areas) presented the lowest values of diversity. Analysis of the community structure showed that endemic butterfly species were associated with fragmented areas in the high mountains. Findings from this study, the first of its kind to determine changes in butterfly diversity in highlands in northeastern Colombia, may help to generate conservation strategies in places where there is high endemism and diversityLa región andina se caracteriza por albergar una gran variedad de ecosistemas entre los que se cuentan las características zonas de alta montaña, que muestran acelerados procesos de transformación del suelo que han convertido los bosques nativos en zonas agrícolas y ganaderas ocasionando un declive de la diversidad biológica regional. El empleo de indicadores de diversidad es adecuado para evaluar los cambios en los paisajes de alta montaña, siendo las mariposas uno de los grupos más importantes para determinar los cambios que se producen en los diferentes tipos de ambientes. En el área de estudio se establecieron doce puntos de muestreo en los complejos de páramos del Almorzadero, Santurbán y Tamá de la región nororiental de Colombia. Durante la fase de muestreo se realizaron capturas de individuos adultos de mariposas en transectos de 100 x 4 m en un gradiente altitudinal de 500 m. Se registraron 69 especies, pertenecientes a cinco familias. Los valores de diversidad de la comunidad de mariposas diurnas variaron en las diferentes coberturas vegetales asociadas a cada transecto. Así, las áreas con cobertura vegetal conservada (por ejemplo, bosque denso, arbustos y matorrales y páramo y subpáramo) presentaron los valores más altos de diversidad, mientras que las zonas con cobertura alterada (por ejemplo, bosque fragmentado, pastos y áreas agrícolas) presentaron los valores de diversidad más bajos. Los análisis de estructura de comunidades evidencian que las especies de mariposas endémicas están asociadas a áreas fragmentadas en las zonas de alta montaña. Este estudio es el primero de su tipo que establece cambios en la diversidad de las mariposas en zonas de alta montaña del nordeste de Colombia y se ha realizado con el propósito de generar estrategias de conservación en lugares que presentan un alto grado de endemismo y diversidad

    Nuclear Reaction Rates in a Plasma

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    The problem of determining the effects of the surrounding plasma on nuclear reaction rates in stars is formulated ab initio, using the techniques of quantum statistical mechanics. We derive a result that expresses the complete effects of Coulomb barrier penetration and of the influence of the surrounding plasma in terms of matrix elements of well defined operators. We find that possible "dynamical screening" effects that have been discussed in the literature are absent. The form of our results suggests that an approach that relies on numerical calculations of the correlation functions in a classical Coulomb gas, followed by construction of an effective two body potential and a quantum barrier penetration calculation, will miss physics that is as important as the physics that it includes.Comment: 66 pages, revtex, Errors Fixed, Explanation Adde

    Deciphering past and present atmospheric metal pollution of urban environments: The role of black crusts formed on historical constructions

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    Construction materials affected by black crusts (BCs) can be subjected to restoration, demolition, recycling or even to their management as waste products. Therefore, the determination of their chemical features should be considered a crucial step before undertaking any action. In this work, we present the development of an analytical methodology useful to be implemented as a routine screening tool to detect recent and past atmospheric emissions of heavy metals, nowadays superficially deposited or even encapsulated in BCs. For its development, BCs together with the underneath original substrate/construction material were sampled from the historical construction Punta Begona Galleries (Getxo, Basque Country, North of Spain). In order to detect quickly and in a cost-effective way the stratification of the metallic deposits in the BCs over time (surface or external/recent and internal/past), thin sections were analyzed by elemental spectroscopic imaging techniques (SEM-EDS and mu-ED-XRF). In the external part of the BCs, iron particles were mainly identified, whereas in the inner areas (past deposition events) of the most exposed BCs to the atmosphere, lead accumulations together with zinc and copper were identified. Additional Raman imaging studies allowed to perform the molecular speciation study of lead, identifying mainly laurionite (PbClOH) together with hydrocerussite (Pb-3(CO3)(2)(OH)(2)). The presence of the mentioned lead chloride hydroxide confirms the role of the marine aerosol (chloride input) in the formation of the metallic compounds. These experimental evidences were used to assist the chemical equilibrium models developed to explain the reactivity pathway, which lead to the formation of the identified compounds. Through ICP-MS and lead isotopic ratio analysis, more than 3000 mg kg(-1) of lead were quantified in the BCs, probably coming from the old emissions conducted by the old power station close to the construction,. That lead content can be high enough to consider those crusts as a source of metallic contamination and a possible risk to the environment and human health

    Shale Water Desalination: Multistage membrane distillation considering different configurations and heat integration

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    This work introduces a simultaneous synthesis of membrane distillation systems with heat exchanger networks (HENs) for desalinating shale gas flowback and produce water. The direct contact and vacuum membrane configurations are the best options for desalination. Moreover, multistage membrane distillation systems usually have higher efficiencies than single-stages processes. For this reason, two different mathematical models for synthetizing multistage direct contact membrane distillation (MSDCMD) and multistage vacuum membrane distillation (MSVMD) are developed and optimized to achieve zero liquid discharge (ZLD) conditions. To this aim, brine discharges are considered to be near to the salt saturation conditions. The multi-stage superstructures are implemented in GAMS and optimized by SBB solver. The mathematical model is formulated via generalized disjunctive programming (GDP) and mixed-integer nonlinear programming (MINLP), to minimize the total annualized cost.This project has received funding from the European Union’s Horizon 2020 Research and Innovation Programme under grant agreement No. 640979

    Listeriolysin O Is Strongly Immunogenic Independently of Its Cytotoxic Activity

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    The presentation of microbial protein antigens by Major Histocompatibility Complex (MHC) molecules is essential for the development of acquired immunity to infections. However, most biochemical studies of antigen processing and presentation deal with a few relatively inert non-microbial model antigens. The bacterial pore-forming toxin listeriolysin O (LLO) is paradoxical in that it is cytotoxic at nanomolar concentrations as well as being the source of dominant CD4 and CD8 T cell epitopes following infection with Listeria monocytogenes. Here, we examined the relationship of LLO toxicity to its antigenicity and immunogenicity. LLO offered to antigen presenting cells (APC) as a soluble protein, was presented to CD4 T cells at picomolar to femtomolar concentrations- doses 3000–7000-fold lower than free peptide. This presentation required a dose of LLO below the cytotoxic level. Mutations of two key tryptophan residues reduced LLO toxicity by 10–100-fold but had no effect on its presentation to CD4 T cells. Thus there was a clear dissociation between the cytotoxic properties of LLO and its very high antigenicity. Presentation of LLO to CD8 T cells was not as robust as that seen in CD4 T cells, but still occurred in the nanomolar range. APC rapidly bound and internalized LLO, then disrupted endosomal compartments within 4 hours of treatment, allowing endosomal contents to access the cytosol. LLO was also immunogenic after in vivo administration into mice. Our results demonstrate the strength of LLO as an immunogen to both CD4 and CD8 T cells

    Nutritional status and the risk of malnutrition in older adults with chronic kidney disease – implications for low protein intake and nutritional care: A critical review endorsed by ERN-ERA and ESPEN

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    Increased life expectancy is posing unprecedented challenges to healthcare systems worldwide. These include a sharp increase in the prevalence of chronic kidney disease (CKD) and of impaired nutritional status with malnutrition-protein-energy wasting (PEW) that portends worse clinical outcomes, including reduced survival. In older adults with CKD, a nutritional dilemma occurs when indications from geriatric nutritional guidelines to maintain the protein intake above 1.0 g/kg/day to prevent malnutrition need to be adapted to the indications from nephrology guidelines, to reduce protein intake in order to prevent or slow CKD progression and improve metabolic abnormalities. To address these issues, the European Society for Clinical Nutrition and Metabolism (ESPEN) and the European Renal Nutrition group of the European Renal Association (ERN-ERA) have prepared this conjoint critical review paper, whose objective is to summarize key concepts related to prevention and treatment of both CKD progression and impaired nutritional status using dietary approaches, and to provide guidance on how to define optimal protein and energy intake in older adults with differing severity of CKD. Overall, the authors support careful assessment to identify the most urgent clinical challenge and the consequent treatment priority. The presence of malnutrition-protein-energy wasting (PEW) suggests the need to avoid or postpone protein restriction, particularly in the presence of stable kidney function and considering the patient's preferences and quality of life. CKD progression and advanced CKD stage support prioritization of protein restriction in the presence of a good nutritional status. Individual risk-benefit assessment and appropriate nutritional monitoring should guide the decision-making process. Higher awareness of the challenges of nutritional care in older adult patients with CKD is needed to improve care and outcomes. Research is advocated to support evidence-based recommendations, which we still lack for this increasingly large patient subgroup

    Spinal cord from body donors is suitable for multicolor immunofluorescence

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    Immunohistochemistry is a powerful tool for studying neuronal tissue from humans at the molecular level. Obtaining fresh neuronal tissue from human organ donors is difficult and sometimes impossible. In anatomical body donations, neuronal tissue is dedicated to research purposes and because of its easier availability, it may be an alternative source for research. In this study, we harvested spinal cord from a single organ donor 2 h (h) postmortem and spinal cord from body donors 24, 48, and 72 h postmortem and tested how long after death, valid multi-color immunofluorescence or horseradish peroxidase (HRP) immunohistochemistry is possible. We used general and specific neuronal markers and glial markers for immunolabeling experiments. Here we showed that it is possible to visualize molecularly different neuronal elements with high precision in the body donor spinal cord 24 h postmortem and the quality of the image data was comparable to those from the fresh organ donor spinal cord. High-contrast multicolor images of the 24-h spinal cords allowed accurate automated quantification of different neuronal elements in the same sample. Although there was antibody-specific signal reduction over postmortem intervals, the signal quality for most antibodies was acceptable at 48 h but no longer at 72 h postmortem. In conclusion, our study has defined a postmortem time window of more than 24 h during which valid immunohistochemical information can be obtained from the body donor spinal cord. Due to the easier availability, neuronal tissue from body donors is an alternative source for basic and clinical research

    Prevalence of chronic kidney disease in women of reproductive age and observed birth rates

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    INTRODUCTION: Women of reproductive age with chronic kidney disease (CKD) are recognised to have decreased fertility and a higher risk of adverse pregnancy outcomes. How often CKD afflicts women of reproductive age is not well known. This study aimed to evaluate the burden of CKD and associated birth rates in an entire region.METHODS: This was a retrospective cohort study including women of childbearing age in Stockholm during 2006-2015. We estimated the prevalence of "probable CKD" by the presence of an ICD-10 diagnosis of CKD, a single estimated glomerular filtration rate (eGFR) &lt; 60 mL/min/1.73 m2 or history of maintenance dialysis. By linkage with the Swedish Medical Birth Register we identified births during the subsequent three years from study inclusion and evaluated birth rates.RESULTS: We identified 817,730 women in our region, of whom 55% had at least one creatinine measurement. A total of 3938 women were identified as having probable CKD, providing an age-averaged CKD prevalence of 0.50%. Women with probable CKD showed a lower birth rate 3 years after the index date (35.7 children per 1000 person years) than the remaining women free from CKD (46.5 children per 1000 person years).CONCLUSION: As many as 0.50% of individuals in this cohort had probable CKD, defined on the basis of at least one eGFR&lt;60 ml/min1.73 m2 test result, dialysis treatment (i.e. CKD stages 3-5) or an ICD-10 diagnosis of CKD. This prevalence is lower than previous estimates. Women with probable CKD, according to a study mainly capturing CKD 3-5, had a lower birth rate than those without CKD, illustrating the challenges of this population to successfully conceive.</p

    Optimal Shale Gas Flowback Water Desalination under Correlated Data Uncertainty

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    Presentation at the 27th European Symposium on Computer-Aided Process Engineering (ESCAPE-27), Barcelona, 2017, 1-5 October.Optimal flowback water desalination is critical to improve overall efficiency and sustainability of shale gas production. Nonetheless, great uncertainty in well data from shale plays strongly hinders the design task. In this work, we introduce a new stochastic multiscenario optimization model for the robust design of desalination systems under uncertainty. A zero-liquid discharge (ZLD) system composed by multiple-effect evaporation with mechanical vapor recompression (MEE-MVR) is proposed for the desalination of high-salinity shale gas flowback water. Salinity and flowrate of flowback water are both considered as uncertain design parameters, which are described by correlated scenarios with given probability of occurrence. The set of scenarios is generated via Monte Carlo sampling technique from a multivariate normal distribution. ZLD operation is ensured by the design constraint that allows brine concentration near to salt saturation conditions for all scenarios. The stochastic multiscenario nonlinear programming (NLP) model is optimized in GAMS, through the minimization of the expected total annualized cost. Risk analysis based on cumulative probability curves is performed in the uncertain search space, to support decision-makers towards the selection of more robust ZLD desalination systems applied to shale gas flowback water.This project has received funding from the European Union's Horizon 2020 research and innovation program under grand agreement No 640979
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