1,142 research outputs found

    Intensification of livestock farming in times of climate change: The challenges of domestic grazing in the drylands of the Argentine Patagonia

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    Livestock grazing modifies and even degrades arid ecosystems, which threatens the sustainability of livestock farming itself. It is essential to learn more about the effects of grazing on vegetation and soil to design strategies to avoid desertification, perhaps the most serious problem faced by drylands. In this paper, we evaluate the changes in the functional traits of the plant community and the biological soil crust induced by the intensification of grazing in Patagonian ecosystems. This description, together with changes in diversity, plant composition, and ecosystem functioning, can help us to understand the mechanisms by which the intensification of sheep grazing could degrade arid ecosystems.; El pastoreo con ganado modifica los ecosistemas áridos y llega incluso a degradarlos, lo que atenta contra la sustentabilidad de la propia actividad ganadera. Resulta clave conocer los efectos del pastoreo sobre la vegetación y el suelo para poder diseñar estrategias que eviten la desertificación, quizá el problema más grave que encaran los ecosistemas áridos. En este artículo, evaluamos los cambios en los rasgos funcionales de la comunidad vegetal y la costra biológica del suelo inducidos por la intensificación del pastoreo en ecosistemas patagónicos. Esta descripción, junto con los cambios en la diversidad, composición y funcionamiento ecosistémico, ayuda a comprender los mecanismos por los que la intensificación del pastoreo ovino podría degradar los ecosistemas áridos.; El pasturatge amb bestiar modifica els ecosistemes àrids i fins i tot arriba a degradar-los, cosa que atempta contra la sostenibilitat de la mateixa activitat ramadera. Resulta clau conèixer els efectes del pasturatge sobre la vegetació i el sòl per a poder dissenyar estratègies que eviten la desertificació, potser el problema més greu que encaren els ecosistemes àrids. En aquest article, avaluem els canvis en els trets funcionals de la comunitat vegetal i la crosta biològica del sòl induïts per la intensificació del pasturatge en ecosistemes patagònics. Aquesta descripció, juntament amb els canvis en la diversitat, composició i funcionament ecosistèmic, ajuda a comprendre els mecanismes pels quals la intensificació del pasturatge oví podria degradar els ecosistemes àrids

    A Computational Channel Model for Magnetic Induction-Based Subsurface Applications

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    There are many underground applications based on magnetic fields generated by an oscillating magnetic source. For them, a magnetic dipole in a three-layered region with upper semi-infinite air layer can be a convenient idealization used for their planning, development, and operation. Solutions are in the form of the well-known Sommerfeld integral expressions that can be evaluated by numerical methods. A set of field expressions to be numerically evaluated by an efficient algorithm are not collected comprehensively yet, or at least in a directly usable form. In this paper, the explicit magnetic field solutions for the vertical magnetic dipole and the horizontal magnetic dipole for a general source-observer location are derived from the Hertz vector. They can be properly combined to model the problem of a tilted magnetic dipole source for horizontally or inclined stratified media. As a result, a complete set of integral equations of the Sommerfeld type valid from the near zone to the far zone are formulated. A method for numerical evaluation of the field expressions for high accurate computations is described. The numerical results are validated using the finite element method for all the possible source-receiver configurations and three well-spanned frequencies of typical subsurface applications. Both numerical solutions agree according to the normalized root-mean-square error-based fit metric. Numerical results for two cases of study are presented to see its usefulness for subsurface applications. A MATLAB implementation of the mathematical description outlined in this paper and the proposed evaluation method is freely available for download

    Interleukin-8 expression in bronchoalveolar lavage cells in the evaluation of alveolitis in idiopathic pulmonary fibrosis

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    AbstractInterleukin-8 (IL-8) is a neutrophilic chemotactic factor which may have a prominent role in the attraction of neutrophils to the lung in idiopathic pulmonary fibrosis (IPF). The objective of this study was to investigate the usefulness of IL-8 expression in bronchoalveolar lavage (BAL) cells in the evaluation of alveolitis in IPF. We analysed the BAL cell expression of IL-8 by immunocytochemistry in 19 patients with IPF (six smokers, three ex-smokers and ten non-smokers) and in a control group composed of 14 individuals (six smokers, eight non-smokers). In IPF, BAL was performed on both the pulmonary lobe with the most extensive involvement and the one less extensively involved on high-resolution computed tomography (HRCT) scans. The percentages and absolute numbers of BAL IL-8+ macrophages from lobes with the most extensive HRCT scan involvement (36 ± 6% and (6 ± 2 × 104 ml−1) (SE) and from those less extensively involved [26% ± 4% and (6 ± 1) × 104 ml−1] were significantly higher with respect to both those from healthy smokers [17% ± 6% and (7 ± 4) × 104 ml−1] and those from non-smokers [2% ± 1% and (1 ± 0·3) × 104 ml−1] (P=0·005 and P=0·001, respectively), without differences between the two lobes. In contrast, both the proportions and the absolute numbers of BAL neutrophils in IPF were significantly higher in lobes with the most extensively involved HRCT scan in comparison with lobes with the least extensive involvement [13% ± 3%, (3 ± 1) × 104 ml−1 vs. 8% ± 2%, (1 ± 0·3) × 104 ml−1, P=0·05]. Moreover, the numbers of BAL neutrophils, but not those of IL-8+ macrophages, correlated with the extent of total pulmonary HRCT scan abnormalities in the most involved lobe (r=0·64, P=0·04). A correlation between neutrophils and IL-8+ cells was not observed. The results of this study suggest that, in IPF, BAL neutrophilia offers a better description of the disease inflammatory process than the expression of IL-8 in BAL cells

    Action of phenylephrine on protein synthesis in liver cells

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    Dynamic soluble changes in sVEGFR1, HGF, and VEGF promote chemotherapy and bevacizumab resistance: A prospective translational study in the BECOX (GEMCAD 09-01) trial

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    Despite initial responsiveness, acquired resistance to both bevacizumab and chemotherapy in metastatic colorectal cancer is universal. We have recently published that in vitro, chronically oxaliplatin resistance upregulates soluble vascular endothelial growth factor receptor 1, downregulates vascular endothelial growth factor, and also promotes c-MET, b-ca catenin/transcription factor 4, and AKT activation. We tested whether variation in three serum biomarkers such as the natural c-MET ligand (hepatocyte growth factor), soluble vascular endothelial growth factor receptor 1, and vascular endothelial growth factor-A was associated with efficacy in metastatic colorectal cancer patients treated in the prospective BECOX study. Serum levels of vascular endothelial growth factor-A165, soluble vascular endothelial growth factor receptor 1, and hepatocyte growth factor were assessed by enzyme-linked immunosorbent assay method basally and every 3 cycles (at the time of computed tomography evaluation) in a preplanned translational study in the first-line BECOX trial in metastatic colorectal cancer patients treated with CAPOX plus bevacizumab. Response was evaluated by routine contrast-enhanced computed tomography by RECIST 1.1 by investigator assessment and by three blinded independent radiologists. Ratios between soluble vascular endothelial growth factor receptor 1/vascular endothelial growth factor-A and hepatocyte growth factor/vascular endothelial growth factor-A were established and variations through time were related to RECIST 1.1 by investigator assessment and independent radiologist. The BECOX trial included 68 patients, and 27 patients were analyzed in the translational trial. A total of 80 RECIST 1.1 evaluations were done by investigator assessment and 56 by independent radiologist. We found that a 3.22-fold increase in soluble vascular endothelial growth factor receptor 1/vascular endothelial growth factor-A by investigator assessment and a 3.06-fold increase in soluble vascular endothelial growth factor receptor 1/vascular endothelial growth factor-A by independent radiologist from previous determination were associated with responses compared with 1.38-fold increase by investigator assessment and 1.59 by independent radiologist in non-responders (p= 0.0009 and p = 0.03, respectively). Responders had a 3.36-fold increase in hepatocyte growth factor/vascular endothelial growth factor-A from previous determination by investigator assessment and 3.66-fold increase in hepatocyte growth factor/vascular endothelial growth factor-A by independent radiologist compared with 1.43-fold increase by investigator assessment and 1.53 by independent radiologist for non-responders (p = 0.002 and 0.003, respectively). In conclusion, a decrease in vascular endothelial growth factor-A and an increase in soluble vascular endothelial growth factor receptor 1 during chemotherapy and bevacizumab exposure can contribute to both chemotherapy (due to c- MET/b-catenin activation) and bevacizumab (due to low vascular endothelial growth factor requirements) resistance. Because hepatocyte growth factor levels decrease also during acquired resistance, alternative strategies to hepatocyte growth factor–ligand inhibition should be investigatedThis work was supported by “beca SEOM a Jóvenes Investigadores 2009” and by the Emili Letang fellowship to Estela Pineda

    A proposal for the maximum use of recycled concrete sand in masonry mortar design

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    Natural sand mining from rivers and seashores is causing serious environmental problems in many parts of the world, whereas the fine fraction from recycling concrete waste is underutilized as a construction material. The aim of this paper is to determine the maximum replacement level of natural sand by recycled sand in the manufacturing of masonry mortar (M-10). For this purpose, five replacement levels were tested: 0%, 25%, 50%, 75% and 100% by volume. The mixes were made using cement CEM II/BL 32.5 N in a volumetric proportion of cement-to-aggregate of 1:5. A commercial admixture was used at a constant content. The amount of water was variable to achieve a consistency of 175±10 mm. The short- and long-term mortar properties were evaluated. The data were analyzed using a one-way ANOVA. In conclusion, a maximum percentage of 50% recycled concrete sand can be used in an indoor environment.<br><br>La extracción de arena natural de ríos y costas está provocando graves problemas ambientales en muchas partes del mundo, mientras que la fracción fina de los áridos reciclados de residuos de hormigón está infrautilizada como material de construcción. El objetivo de este artículo es determinar el máximo porcentaje de sustitución de arena natural por arena reciclada en la fabricación de morteros M-10. Cinco niveles de sustitución en volumen fueron ensayados: 0%, 25%, 50%, 75% y 100%. Las mezclas fueron hechas con cemento CEM II/BL 32,5 N en una relación volumétrica cemento-árido de 1:5. Se utilizó un aditivo comercial a dosis constante. El agua se ajustó experimentalmente para conseguir una consistencia de 175±10 mm. Se evaluaron las propiedades de los morteros a corto y largo plazo. Los datos se analizaron mediante una ANOVA-simple. En conclusión, un porcentaje máximo del 50% de arena reciclada de hormigón puede usarse en interiores

    Psychometric properties of a revised Spanish 20-item Toronto Alexithymia Scale adaptation in multiple sclerosis patients

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    There have been a small number of investigations of alexithymia in multiple sclerosis (MS) using the 20-item Toronto Alexithymia Scale (TAS-20). However, the TAS-20 factor structure has not yet been evaluated in a MS patient sample, and earlier Spanish translations of this instrument require some improvement. We aimed to evaluate the factorial validity and reliability of an improved Spanish translation of the TAS-20 (the TAS-20-S). The TAS-20-S was completed by 221 MS patients. Confirmatory factor analysis was used to compare the fit of six different factor models. Internal consistency and retest reliability coefficients were also computed. The correlated three-factor model and the higher-order factor model made up of Difficulty Identifying Feelings, Difficulty Describing Feelings, and Externally Oriented Thinking achieved the best fit. Alpha coefficients ranged between .87 and .67; mean inter-item correlations ranged between .48 and .20; and retest correlations after 6 months ranged between .61 and .52. A high degree of alexithymia was present in 18.1% of the sample. Reliability and the traditional three-factor structure were demonstrated for the TAS-20-S, which can now be recommended for assessing an aspect of emotional processing in MS patients.En la esclerosis múltiple (EM) son escasas las investigaciones centradas en evaluar la alexitimia con la Escala de Alexitimia de Toronto (TAS-20). A pesar de ello, no se ha evaluado aún su estructura factorial en dicha población y, además, las anteriores traducciones al español necesitan modificaciones. Los objetivos del presente estudio fueron evaluar la validez factorial y la fiabilidad de una traducción mejorada en español de la TAS-20 (la TAS-20-S), la cual fue administrada en una muestra de 221 pacientes con EM. Se realizaron análisis factoriales confirmatorios para comparar el ajuste de seis modelos factoriales. También se calcularon coeficientes de consistencia interna y de fiabilidad test-retest. Los modelos trifactorial correlacionado y el de orden superior conformados por Dificultad en Identificar Sentimientos, Dificultad en Describir Sentimientos y Pensamiento Externamente Orientado lograron el mejor ajuste. Los coeficientes alfa oscilaron entre 0,87 y 0,67; las correlaciones medias inter-ítem entre 0,48 y 0,20; y las correlaciones test-retest tras 6 meses oscilaron entre 0,61 y 0,52. El 18,10% de la muestra presentó niveles elevados de alexitimia. La TAS-20-S presentó una adecuada fiabilidad así como la tradicional estructura trifactorial, por lo que su uso es ahora recomendable para evaluar un aspecto del procesamiento emocional en EM.Ministerio de Educación, Cultura y Deporte de España Programa FPU (Formación del Profesorado Universitario
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