297 research outputs found

    Abstract robust coarse spaces for systems of PDEs via generalized eigenproblems in the overlaps

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    Coarse spaces are instrumental in obtaining scalability for domain decomposition methods for partial differential equations (PDEs). However, it is known that most popular choices of coarse spaces perform rather weakly in the presence of heterogeneities in the PDE coefficients, especially for systems of PDEs. Here, we introduce in a variational setting a new coarse space that is robust even when there are such heterogeneities. We achieve this by solving local generalized eigenvalue problems in the overlaps of subdomains that isolate the terms responsible for slow convergence. We prove a general theoretical result that rigorously establishes the robustness of the new coarse space and give some numerical examples on two and three dimensional heterogeneous PDEs and systems of PDEs that confirm this property

    Physical demand but not dexterity is associated with motor flexibility during rapid reaching in healthy young adults

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    Healthy humans are able to place light and heavy objects in small and large target locations with remarkable accuracy. Here we examine how dexterity demand and physical demand affect flexibility in joint coordination and end-effector kinematics when healthy young adults perform an upper extremity reaching task. We manipulated dexterity demand by changing target size and physical demand by increasing external resistance to reaching. Uncontrolled manifold analysis was used to decompose variability in joint coordination patterns into variability stabilizing the end-effector and variability de-stabilizing the end-effector during reaching. Our results demonstrate a proportional increase in stabilizing and de-stabilizing variability without a change in the ratio of the two variability components as physical demands increase. We interpret this finding in the context of previous studies showing that sensorimotor noise increases with increasing physical demands. We propose that the larger de-stabilizing variability as a function of physical demand originated from larger sensorimotor noise in the neuromuscular system. The larger stabilizing variability with larger physical demands is a strategy employed by the neuromuscular system to counter the de-stabilizing variability so that performance stability is maintained. Our findings have practical implications for improving the effectiveness of movement therapy in a wide range of patient groups, maintaining upper extremity function in old adults, and for maximizing athletic performance

    Seasonality, richness and prevalence of intestinal parasites of three neotropical primates (Alouatta seniculus, Ateles hybridus and Cebus versicolor) in a fragmented forest in Colombia

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    Studies on parasites infecting non-human primates are essential to better understand the potential threat to humans of zoonoses transmission, particularly under the current processes of pervasive land use change and biodiversity loss. The natural ecosystems in the Middle Magdalena river basin in Colombia have suffered a dramatic reduction and transformation into pastures and agroindustrial monocultures, threatening their biodiversity, and probably affecting the dynamics between parasites and their hosts, as well as altering the disease transmission cycles between wild populations and humans. This study evaluated seasonality, prevalence and richness of intestinal parasites in three species of neotropical primates: Cebus versicolor, Ateles hybridus and Alouatta seniculus, in a fragmented forest in the Middle Magdalena river valley, Colombia. One hundred and eighty five faecal samples were collected between 2010 and 2015. Direct faecal smears were performed with saline solution (0.85%) and iodine solution (1%), in order to identify larvae and eggs based on their morphology. A large proportion of the samples examined (72.9%) was positive for intestinal parasites; seven families of nematodes were identified: Trichuridae, Trichostrongylidae, Oxyuridae, Strongyloididae, Ancylostomatidae, Ascarididae and Gnathostomatidae, two of protozoans: Entamoebidae and Balantiididae, as well as some eggs of trematodes, cestodes and acanthocephalans. Additionally, DNA extraction and sequencing were conducted on 30 faecal samples in order to identify Giardia sp. and Blastocystis hominis, two parasite species also present in humans. Molecular testing for Giardia sp. was negative and Blastocystis hominis was identified in a single sample of Alouatta seniculus. No clear patterns were observed for prevalence of intestinal parasites according to the season; nonetheless, parasite species richness was higher during the dry season. This study builds on our current understanding of intestinal parasites infecting wild neotropical primates and provides novel information on the patterns of intestinal parasites in primate communities exposed to anthropogenic disturbance

    Monitoring root rot in flat-leaf parsley via machine vision by unsupervised multivariate analysis of morphometric and spectral parameters

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    \ua9 The Author(s) 2024.Use of vertical farms is increasing rapidly as it enables year-round crop production, made possible by fully controlled growing environments situated within supply chains. However, intensive planting and high relative humidity make such systems ideal for the proliferation of fungal pathogens. Thus, despite the use of bio-fungicides and enhanced biosecurity measures, contamination of crops does happen, leading to extensive crop loss, necessitating the use of high-throughput monitoring for early detection of infected plants. In the present study, progression of foliar symptoms caused by Pythium irregulare-induced root rot was monitored for flat-leaf parsley grown in an experimental hydroponic vertical farming setup. Structural and spectral changes in plant canopy were recorded non-invasively at regular intervals using a 3D multispectral scanner. Five morphometric and nine spectral features were selected, and different combinations of these features were subjected to multivariate data analysis via principal component analysis to identify temporal trends for early segregation of healthy and infected samples. Combining morphometric and spectral features enabled a clear distinction between healthy and diseased plants at 4–7 days post inoculation (DPI), whereas use of only morphometric or spectral features allowed this at 7–9 DPI. Minimal datasets combining the six most effective features also resulted in effective grouping of healthy and diseased plants at 4–7 DPI. This suggests that selectively combining morphometric and spectral features can enable accurate early identification of infected plants, thus creating the scope for improving high-throughput crop monitoring in vertical farms

    Diseño de un sistema de tratamiento para el agua residual en el proceso de beneficio de café

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    Existe una problemática en el manejo inadecuado del mucílago de café, el cual se convierte en agua residual durante el proceso de beneficio tradicional de este. Esta agua residual es tan alta en las regiones cafeteras de Colombia, como lo es en el municipio de Socorro en el departamento de Santander. Las razones se deben, en la mayoría de los casos, a la falta de compromiso de la entidad ambiental y al desconocimiento del tema en general por parte de los caficultores. Este documento hace referencia al tratamiento del mucílago de café, el tipo de tratamiento, las variables para tomar la decisión de escoger las unidades operacionales del mismo, y el diseño para lograr la disminución de la contaminación del cuerpo receptor. Todo ello basado en el RAS 2000 y en experiencias de algunos autores sobre el tema. Adicionalmente se buscó aportar a los caficultores de esta región nuevas estrategias para el tratamiento de dicho subproducto, introduciendo conceptos ecológicos en el proceso de beneficio del café, que respondan a exigencias legales y ambientales y, por lo tanto, mejoren su calidad de vida y la de sus familias. De esta forma, el objetivo principal de este proyecto consistió en diseñar un sistema de tratamiento para el agua residual en el proceso de beneficio de café en la finca La Primavera, ubicada en la vereda Alto de Reinas, del municipio del Socorro, Santander. Como resultado se realizó el diseño del sistema para la gestión integral del manejo y tratamiento del agua residual generada en el proceso de beneficio de café. Asimismo, se generó una hoja de cálculo y planos en detalle de los sistemas propuestos, para facilitar el diseño y la construcción, al momento de que algún ente ya sea ambiental o privado decida implementarlo

    Evaluation of agraz consumption on adipocytokines, inflammation, and oxidative stress markers in women with metabolic syndrome

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    ABSTRACT: Metabolic syndrome (MetS) is characterized by increased oxidative stress and a pro-inflammatory state. Vaccinium meridionale Swartz (known as “agraz”) is a berry rich in polyphenolic compounds with demonstrated antioxidant activity and anti-inflammatory effects in preclinical studies. The aim of this study was to evaluate the effects of agraz consumption on inflammatory and oxidative stress markers in women with MetS. Forty women with MetS (47 ± 9 years) were randomly assigned to consume daily either 200 mL of agraz nectar or placebo over four weeks in a double-blind, cross-over design study, separated by a 4-week washout period. Metabolic and inflammatory markers in serum and antioxidant/oxidative stress markers in serum and urine were assessed at the end of each period. Serum antioxidant capacity measured by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) method was significantly higher (p = 0.028), while urinary 8-hydroxy-2-deoxyguanosine (8-OHdG) was lower (p = 0.041) after agraz consumption, compared to placebo. In conclusion, consumption of agraz during four weeks increased serum antioxidant capacity and decreased a marker of DNA oxidative damage in women with MetS, compared to placebo. These results suggest that agraz consumption may play a protective role in patients with MetS

    Effect of Agraz (Vaccinium meridionale Swartz) on high-density lipoprotein function and inflammation in women with metabolic syndrome

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    ABSTRACT: Metabolic syndrome (MetS) is associated with low-grade inflammation and high-density lipoprotein (HDL) dysfunction. Polyphenol-rich foods may improve these alterations. Agraz is a fruit rich in polyphenols (mainly anthocyanins); however, there is limited information about its effects on human health. We evaluated the effects of agraz consumption as compared to placebo on HDL function and inflammation in women with MetS. Forty volunteers (25–60 years) were included in this double-blind crossover study. Women consumed agraz or placebo over 4 weeks; separated by a 4-week washout period. HDL function (apoliprotein-A1; paraoxonase 1 (PON1) activity; cholesterol efflux capacity), oxidative stress (myeloperoxidase (MPO), advanced oxidation protein products) and inflammatory markers (serum cytokines/chemokines and peripheral blood mononuclear cell nuclear factor-kB) were measured after each period. Compared to placebo, agraz consumption did not significantly change any of the biomarkers measured. Interestingly, only after agraz period there were significant positive correlations between PON1 activities and cholesterol efflux. Additionally, there were significant inverse correlations between changes in inflammatory markers and HDL function markers and positive correlations with oxidative markers. Although polyphenol-rich foods have been shown to be beneficial for certain conditions; polyphenol-rich agraz fruit consumption did not impact inflammation and HDL function in the current study of women with MetS

    Caracterización epidemiológica de la diarrea neonatal aguda indiferenciada (DNAI) en ganaderías lecheras del valle de Ubaté.

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    Se estudió la epidemiología de la diarrea neonatal aguda indiferenciada (DNAI) en ganaderías de leche del valle de Ubaté mediante encuestas en 49 fincas. La DNAI afectó a los bovinos neonatos con prevalencia instantánea de 8.3 por ciento para la zona y de 9.6 por ciento para fincas afectadas, los animales de ambos sexos menores de 1 semana e hijos de vacas primerizas constituyeron el grupo de edad más afectado. La entidad patológica se vió favorecida por la alcalinización semestral de las praderas, el consumo de pastos muy tiernos por parte de las madres, la alimentación de los terneros por medio de baldes o cubos, la permanencia de madres y crías en el sitio de parición por períodos entre 15 y 60 días, la desinfección de implementos y utensilios propios del manejo animal con agua, jabón, desinfectantes y el uso de antiparasitarios internos sólo cada tres meses. Se calculan algunas pérdidas económicas, se discute el hecho de que la DNAI es producto de la interacción entre organismos causales, medio ambiente y sistema de explotación. Se sugieren algunas medidas de prevención y controlGanado de leche-Ganadería lech

    Las ametropías: revisión actualizada para médicos no oftalmólogos

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    Los defectos de refracción se originan por un desacople entre el poder de convergencia de los lentes del ojo por un lado, es decir la córnea y el cristalino, que hacen que los rayos que llegan al ojo formen un foco y generen una imagen,  y por otro lado la retina, que es la pantalla biológica fotosensible donde esa imagen será transformada en un impulso nervioso. Estos defectos incluyen la miopía, la hipermetropía y el astigmatismo.  La presbicia se puede considerar también un defecto refractivo, pero de características especiales, pues solo afecta la visión próxima en mayores de 40 años. rocedure performed by an experimen enfocada en la mergencia de los lentes del ojo (c ification procedure performed by an experimAl alterar la calidad de la imagen enfocada en la zona mas sensible a la luz de la retina (la mácula), disminuyen la agudeza visual. Para su manejo existen desde el uso de anteojos y lentes de contacto hasta la corrección quirúrgica (cirugía refractiva). La incidencia de ciertos errores de refracción (específicamente de la  miopía) se ha incrementado en la últimas décadas, y se han identificado algunos factores ambientales relacionados con ello. Algunas medidas de manejo médico de la misma han mostrado un efecto positivo en el control de su aparición y progresión.</p

    Three axis vector magnet set-up for cryogenic scanning probe microscopy

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    We describe a three axis vector magnet system for cryogenic scanning probe microscopy measurements. We discuss the magnet support system and the power supply, consisting of a compact three way 100 A current source. We obtain tilted magnetic fields in all directions with maximum value of 5T along z-axis and of 1.2T for XY-plane magnetic fields. We describe a scanning tunneling microscopy-spectroscopy (STM-STS) set-up, operating in a dilution refrigerator, which includes a new high voltage ultralow noise piezodrive electronics and discuss the noise level due to vibrations. STM images and STS maps show atomic resolution and the tilted vortex lattice at 150 mK in the superconductor β-Bi2Pd. We observe a strongly elongated hexagonal lattice, which corresponds to the projection of the tilted hexagonal vortex lattice on the surface. We also discuss Magnetic Force Microscopy images in a variable temperature insertThis work was supported by Convocatoria Doctorados en el Exterior 568-2012 COLCIENCIAS, the Spanish MINECO (FIS2011-23488, MAT2011-27470-C02-02, CSD2009-00013), by the Comunidad de Madrid through program Nanofrontmag-CM (S2013/MIT-2850) and by Marie-Curie actions under the project FP7-PEOPLE-2013- CIG-618321. The research leading to these results has received funding from the European Union Seventh Framework Programme under Grant Agreement No. 604391 Graphene Flagship. We also acknowledge Banco Santander, COST MP1201. J.A. and C.M. acknowledge the FPI (BES- 2012-058600) and Juan de la Cierva (JCI-2011-08815) programs, respectivel
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