2,730 research outputs found

    Localized pulsed nanosecond discharges in a counterflow nonpremixed flame environment

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    A flame is a very unusual environment for the development of a gas discharge, since it presents strong gradients in temperature, composition, and pre-ionization. In this paper we examine how such an environment impacts the development of the plasma when using repetitive pulsed nanosecond discharges, one of the main strategies used in the field of plasma assisted combustion. Experiments were performed in a counterflow nonpremixed burner with parallel electrodes at the nozzle exits and nanosecond-resolved photography of the plasma emission is presented. It was shown that the discharge development in stratified media may take place in the form of a dielectric barrier discharge with a localized energy deposition. In the experiments presented the discharge energy was coupled to the flame front because of the high rate of chemi-ionization and the gas density decrease in the flame

    Avifauna en un area perturbada del bosque andino en el parque nacional natural Farallones de Cali, corregimiento de Pance, Valle del Cauca (Colombia)

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    El presente conjunto de datos en el formato de archivo Darwin Core incluye información del monitoreo de la avifauna en un área perturbada del Parque Nacional Natural Farallones de Cali. Con el objetivo de caracterizar y determinar la composición y estructura de la avifauna, se llevaron a cabo censos visuales desde agosto 2008 hasta julio 2009 en las localidades de El Topacio y El Pato en recorridos de 2 km de longitud, a elevaciones entre 1550 y 1800 m s.n.m. En total se hicieron 2363 registros de 157 especies de aves, pertenecientes a 41 familias y 19 órdenes. Se observaron 12 especies nuevas para el área, 10 de las cuales son aves propias de áreas abiertas. Nueve especies que habían sido registradas en El Topacio en 1978, no lo fueron en el presente estudio y en consecuencia se consideran extintas y vulnerables localmente, lo cual ilustra y ratifica cómo el reemplazo de los hábitats naturales por potreros, la fragmentación y el efecto de borde afectan negativamente las comunidades de aves en áreas protegidas.This dataset in Darwin Core Archive format includes monitoring information about bird life in a disturbed area of the Farallones de Cali National Natural Park. Aiming to characterize and determine the composition and structure of bird life, visual censuses were carried out from August 2008 to July 2009 at both the El Pato and the El Topacio localities along line census of 2 km and from elevations between1550 to 1800 m a.s.l. A total of 2363 records were obtained of 157 species of 41 families and 19 orders. Twelve were new records for the area, 10 of which are common in open areas. Nine species previously recorded in 1978 at El Topacio were absent and considered locally extinct and vulnerable. This illustrates how the replacement of natural habitats with pasturelands, as well as fragmentation and border effect affect negatively bird communities in protected areas.Fil: Bermudez Vera, Julio Cesar . Universidad del Valle. Departamento de Biología; ColombiaFil: Duque Lopez, Juan Sebastian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Patagonia Norte. Centro de Investigación Esquel de Montaña y Estepa Patagónicas; ArgentinaFil: Sanchez Martinez, Manuel A. . Universidad del Valle. Departamento de Biología; ColombiaFil: Tenorio, Elkin . Calima - Fundación para la Investigación de la Biodiversidad y Conservación en el Trópico; Colombi

    Resonant electron transmission through a finite quantum spin chain

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    Electron transport in a finite one dimensional quantum spin chain (with ferromagnetic exchange) is studied within an sds-d exchange Hamiltonian. Spin transfer coefficients strongly depend on the sign of the sds-d exchange constant. For a ferromagnetic coupling, they exhibit a novel resonant pattern, reflecting the salient features of the combined electron-spin system. Spin-flip processes are inelastic and feasible at finite voltage or at finite temperature.Comment: 4 pages including 4 .eps figure

    Use of Native Grassland in Small-Scale Dairy Systems in the Highlands of Central Mexico. A Case Study

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    Small-scale dairy systems in Mexico comprise 78% of specialized dairy farms and provide 37% of national production. They are small farms with herds 3-35 cows plus replacements, and rely on family labour (Posadas-Domínguez et al., 2014). In the highlands, many farms have native grasslands, grazed during the rainy season, and supplemented with other feeds as maize straw, maize grain and maize ears. Native grasslands have not been studied in this context. This is a case study on the use of native grassland in a small-scale dairy farm. The objective was to determine how native grasslands are integrated in feeding milking dairy cows, and the feeding costs involved

    Unsteady Flow and Whirl-Inducing Forces in Axial-Flow Compressors: Part I—Experiment

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    An experimental and theoretical investigation has been conducted to evaluate the effects seen in axial-flow compressors when the centerline of the rotor is displaced from the centerline of the static structure of the engine. This creates circumferentially nonuniform rotor-tip clearances, unsteady flow, and potentially increased clearances if the rotating and stationary parts come in contact. The result not only adversely affects compressor stall margin, pressure rise capability, and efficiency, but also generates an unsteady, destabilizing, aerodynamic force, called the Thomas/Alford force, which contributes significantly to rotor whirl instabilities in turbomachinery. Determining both the direction and magnitude of this force in compressors, relative to those in turbines, is especially important for the design of mechanically stable turbomachinery components. Part I of this two-part paper addresses these issues experimentally and Part II presents analyses from relevant computational models. Our results clearly show that the Thomas/Alford force can promote significant backward rotor whirl over much of the operating range of modern compressors, although some regions of zero and forward whirl were found near the design point. This is the first time that definitive measurements, coupled with compelling analyses, have been reported in the literature to resolve the long-standing disparity in findings concerning the direction and magnitude of whirl-inducing forces important in the design of modern axial-flow compressors

    Up-regulation of HDACs, a harbinger of uraemic endothelial dysfunction, is prevented by defibrotide

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    Altres ajuts: This work was supported by Jazz Pharmaceuticals Plc (IST-16-10355 to MDR. and EC); German José Carreras Leukaemia Foundation (Grant 11R/2016 and 03R/2019 to MDR. and EC); [...]. We would like to thank the Proteomics unit staff (CCIT, University of Barcelona) for their support in the proteomic assay performance and analysis, and to the Primary Hemostasis laboratory group for their technical support. We also acknowledge the collaboration of Dr Josep Maria Cruzado of Institut d'Hemodiàlisi Barcelona who collaborated in obtaining the blood samples, the staff of the Maternitat Hospital, in Barcelona, for providing the umbilical cords that made possible some of the current results and to Shook Studio for the visual abstract design.Endothelial dysfunction is an earlier contributor to the development of atherosclerosis in chronic kidney disease (CKD), in which the role of epigenetic triggers cannot be ruled out. Endothelial protective strategies, such as defibrotide (DF), may be useful in this scenario. We evaluated changes induced by CKD on endothelial cell proteome and explored the effect of DF and the mechanisms involved. Human umbilical cord vein endothelial cells were exposed to sera from healthy donors (n = 20) and patients with end-stage renal disease on haemodialysis (n = 20). Differential protein expression was investigated by using a proteomic approach, Western blot and immunofluorescence. HDAC1 and HDAC2 overexpression was detected. Increased HDAC1 expression occurred at both cytoplasm and nucleus. These effects were dose-dependently inhibited by DF. Both the HDACs inhibitor trichostatin A and DF prevented the up-regulation of the endothelial dysfunction markers induced by the uraemic milieu: intercellular adhesion molecule-1, surface Toll-like receptor-4, von Willebrand Factor and reactive oxygen species. Moreover, DF down-regulated HDACs expression through the PI3/AKT signalling pathway. HDACs appear as key modulators of the CKD-induced endothelial dysfunction as specific blockade by trichostatin A or by DF prevents endothelial dysfunction responses to the CKD insult. Moreover, DF exerts its endothelial protective effect by inhibiting HDAC up-regulation likely through PI3K/AKT

    Exhaled volatilome analysis as a useful tool to discriminate asthma with other coexisting atopic diseases in women of childbearing age

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    ©2021. The authors. This document is made available under the CC-BY 4.0 license http://creativecommons.org/licenses/by /4.0/ This document is published version of a Published Work that appeared in final form in Scientifc Reports. To access the final edited and published work see https://doi.org/10.1038/s41598-021-92933-2The prevalence of asthma is considerably high among women of childbearing age. Most asthmatic women also often have other atopic disorders. Therefore, the diferentiation between patients with atopic diseases without asthma and asthmatics with coexisting diseases is essential to avoid underdiagnosis of asthma and to design strategies to reduce symptom severity and improve quality of life of patients. Hence, we aimed for the frst time to conduct an analysis of volatile organic compounds in exhaled breath of women of childbearing age as a new approach to discriminate between asthmatics with other coexisting atopic diseases and non-asthmatics (with or without atopic diseases), which could be a helpful tool for more accurate asthma detection and monitoring using a noninvasive technique in the near future. In this study, exhaled air samples of 336 women (training set (n= 211) and validation set (n= 125)) were collected and analyzed by thermal desorption coupled with gas chromatography-mass spectrometry. ASCA (ANOVA (analysis of variance) simultaneous component analysis) and LASSO+LS (least absolute shrinkage and selection operator+ logistic regression) were employed for data analysis. Fifteen statistically signifcant models (p-value< 0.05 in permutation tests) that discriminated asthma with other coexisting atopic diseases in women of childbearing age were generated. Acetone, 2-ethyl-1-hexanol and a tetrahydroisoquinoline derivative were selected as discriminants of asthma with other coexisting atopic diseases. In addition, carbon disulfde, a tetrahydroisoquinoline derivative, 2-ethyl-1-hexanol and decane discriminated asthma disease among patients with other atopic disorders. Results of this study indicate that refned metabolomic analysis of exhaled breath allows asthma with other coexisting atopic diseases discrimination in women of reproductive ag
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