3,231 research outputs found

    Influence of serological factors and BMI on the blood pressure/hematocrit association in healthy young men and women.

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    The association between mean arterial blood pressure (MAP) and hematocrit (Hct) as a surrogate for blood viscosity was investigated in a young (average 20.0±2.3 years), healthy population of 174 men and 442 women. Health status was assessed by clinical examination and serological evaluation. Individuals with severe anemia or hemoconcentration, prior traumas or major surgical intervention, smokers, and pregnant or lactating women were excluded from the study. The MAP/Hct association was positive and significant (P=0.04) for women and negative, albeit not significantly so, for men. The MAP/Hct association was also evaluated in subgroups of the same population with a progressive step-by-step exclusion of: individuals with cholesterol >200 mg/dL; triglycerides >200 mg/dL; body mass index >25 kg/m(2); and glucose >100 mg/dL. This consecutively reduced the strength of the positive MAP/Hct association in women, which became negative - although not significantly so - when all anomalously high factors were excluded. The same trend was found in men. Our study indicates that previously reported positive trends in the relationship between the MAP and Hct in the population are not present in a young, healthy population of men or women that excludes individuals with the confounding factors of above normal serological values and BMI

    Making use of the complementarity of hydropower and variable renewable energy in Latin America: A probabilistic analysis

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    Latin America is one of the regions most vulnerable to the effects of climate variability on hydropower generation. Hydropower is the backbone of the Latin-American power system and a key technology for ensuring low-carbon power generation in the region. Despite its importance, our understanding of the impact and likelihood of seasonal variability and of long-term phenomena such as the El Niño Southern Oscillation (ENSO) on hydropower is limited. There is an essential need to understand how likely these effects are and to identify measures to counterbalance them. A combination of wind, solar, and hydropower offers the potential to mitigate the impact of climate variability on renewable power generation and thus improve its reliability. Here we present a modeling framework to quantify the potential benefits of such combination. The modeling framework relies on a meteorological reanalysis dataset, large-scale renewable power generation models, and statistic models. We consider the countries with the largest hydropower capacity in the region, namely Argentina, Brazil, Colombia, Mexico, and Venezuela. We examine whether the probability of a production deficit is reduced when all renewable resources are combined compared to a scenario based solely on hydropower, especially during droughts. The approach presented allows for the first time an in-depth analysis of the benefits of a combined wind, solar, and hydropower-based power generation under different geographical conditions in altered ENSO phases. Our results suggest that—depending on the country and the percentile—the hydropower generated during drought ENSO phases could be up to 50% lower than that during neutral phases. The countries most affected are Colombia and Venezuela, while the reduction is somewhat less severe in Argentina, Brazil, and Mexico. Combining hydropower with variable renewable energy (VRE) offers the potential to reduce the risk of a power deficit during the 10th percentile of the driest months of the year, both in drought and neutral phases. Argentina is the country with the most effective combination of resources to mitigate a power deficit, as each MW of installed VRE generates 0.218 GWh of additional power. It is followed by Brazil and Mexico with 0.185 GWh per MW of VRE and by Venezuela and Colombia with 0.128–0.098 GWh/MW of VRE, respectively. These results can contribute to informing future decisions on capacity planning and regional transmission grids

    La República Popular de China en la Antártida y su acercamiento diplomático a Argentina y Chile

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    Artículo de Miguel Ángel Salazar Urrutia para Antártida: la mirada histórica latinoamericana y su proyección pedagógica integral.Fil: Salazar Urrutia, Miguel A.Salazar Urrutia, M. A. (2021). “La República Popular de China en la Antártida y su acercamiento diplomático a Argentina y Chile”. En Universidad de la Defensa Nacional (Ed.), Antártida: la mirada histórica latinoamericana y su proyección pedagógica integral (pp. 301-327). Buenos Aires: UNDEF Libros

    Black hole fusion in the extreme mass ratio limit

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    We present a simple, general, and accurate construction of the event horizons for the fusion of two neutral, rotating black holes with arbitrary orientation and values of their spins, in the extreme mass ratio limit where one black hole is much larger than the other. We compute several parameters that characterize the fusion and investigate their dependence on the black hole spin and orientation axis. We also exhibit and study the appearance of transient toroidal topology of the horizon. An earlier conjecture about universal critical exponents before and after an axisymmetric pinch is proven

    Social Protection during Disasters: Evidence from the Wenchuan Earthquake

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    Using evidence from the Wenchuan earthquake (12 May 2008) in China, this article examines the impact of disaster on the functioning of China's social protection system. The article examines the social protection system and the recipients of social protection. It presents four main findings: (1) the impact of the disaster on the social protection system itself was considerable; (2) the system was able to cope fairly successfully with the enormous demands created by the earthquake by a surge of resource utilisation; (3) there was an alarming rate of burnout and possible degradation in capabilities after several months, which may affect the effectiveness of the reconstruction stage, and (4) the demands of the public for perfect equality of treatment has hindered targeting of resources, but also simplified the operation at the relief stage. The article concludes with tentative proposals as to the nature of the institutional resilience expressed in the surge

    Blood pressure reduction due to hemoglobin glycosylation in type 2 diabetic patients

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    Pedro Cabrales1, Miguel A Salazar Vázquez2,3, Beatriz Y Salazar Vázquez3,4, Martha Rodríguez-Morán5, Marcos Intaglietta4, Fernando Guerrero-Romero51La Jolla Bioengineering Institute, La Jolla, California, USA; 2Hospital Regional No. 1, of the Mexican Social Security Institute, Victoria de Durango, Dgo. Mexico; 3Faculty of Medicine and Dept. of Physical Chemistry, Universidad Juárez del Estado de Durango, Victoria de Durango, Dgo. Mexico; 4Department of Bioengineering, University of California, San Diego, La Jolla, California, USA; 5Biomedical Research Unit, of the Mexican Social Security Institute, Victoria de Durango, Dgo. MexicoObjective: To test the hypothesis that glycosylation of hemoglobin constitutes a risk factor for hypertension.Methods: A total of 129 relative uniform diabetic subjects (86 women and 42 men) were enrolled in a cross-sectional study. Exclusion criteria included alcohol consumption, smoking, ischemic heart disease, stroke, neoplasia, renal, hepatic, and chronic inflammatory disease. Systolic and diastolic pressures were recorded in subsequent days and mean arterial blood pressure (MAP) was determined. Hemoglobin glycosylation was measured by determining the percentage glycosylated hemoglobin (HbA1c) by means of the automated microparticle enzyme immunoassay test.Results: MAP was found to be independent of the concentration of HbA1c; however, correcting MAP for the variability in hematocrit, to evidence the level of vasoconstriction (or vasodilatation) showed that MAP is negatively correlated with the concentration of HbA1c (p for trend <0.05), when patients treated for hypertension are excluded from the analysis. Patients treated for hypertension showed the opposite trend with increasing MAP as HbA1c increased (p for the difference in trends <0.05).Conclusions: Glycosylation per se appears to lead to blood pressure reduction in type 2 diabetic patients untreated for hypertension. Treatment for hypertension may be associated with a level of endothelial dysfunction that interferes with the antihypertensive effect of HbA1c.Keywords: diabetes, hemoglobin glycosylation, hypertension, hematocrit, nitric oxid

    System analysis of the bio-based economy in Colombia: A bottom-up energy system model and scenario analysis

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    The transition to a sustainable bio‐based economy is perceived as a valid path towards low‐carbon development for emerging economies that have rich biomass resources. In the case of Colombia, the role of biomass has been tackled through qualitative roadmaps and regional climate policy assessments. However, neither of these approaches has addressed the complexity of the bio‐based economy systematically in the wider context of emission mitigation and energy and chemicals supply. In response to this limitation, we extended a bottom‐up energy system optimization model by adding a comprehensive database of novel bio‐based value chains. We included advanced road and aviation biofuels, (bio)chemicals, bioenergy with carbon capture and storage (BECCS), and integrated biorefinery configurations. A scenario analysis was conducted for the period 2015–2050, which reflected uncertainties in the capacity for technological learning, climate policy ambitions, and land availability for energy crops. Our results indicate that biomass can play an important, even if variable, role in supplying 315–760 PJ/y of modern bio‐based products. In pursuit of a deep decarbonization trajectory, the large‐scale mobilization of biomass resources can reduce the cost of the energy system by up to 11 billion $/year, the marginal abatement cost by 62%, and the potential reliance on imports of oil and chemicals in the future. The mitigation potential of BECCS can reach 24–29% of the cumulative avoided emissions between 2015 and 2050. The proposed system analysis framework can provide detailed quantitative information on the role of biomass in low carbon development of emerging economies

    Adaptive mesh refinement in topology optimization

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    This dissertation presents developments in stress constrained topology optimization with Adaptive Mesh Refinement (AMR). Regions with stress concentrations dominate the optimized design. As such, we first present an approach to obtain designs with accurately computed stress fields within the context of topology optimization. To achieve this goal, we invoke threshold and AMR operations during the optimization. We do so in an optimal fashion, by applying AMR techniques that use error indicators to refine and coarsen the mesh as needed. In this way, we obtain accurate simulations and greater resolution of the design domain in a computationally efficient manner. We present results in two dimensions to demonstrate the efficacy of our method. The topology optimization community has regularly employed optimization algorithms from the operations research community. However, these algorithms are implemented in the Euclidean space instead of the proper function space where the design, i.e. volume fraction, field resides. In this thesis, we show that, when discretizing the volume fraction field over a non-uniform mesh, algorithms in Euclidean space are mesh dependent. We do so by first explaining the functional analysis tools necessary to understand why convergence is affected by the mesh. Namely, the distinction between derivative and gradient definitions and the role of the mesh dependent inner product. These tools are subsequently used to make the Globally Convergent Method of Moving Asymptotes (GCMMA), a popular optimization algorithm in the topology optimization community, mesh independent. We then benchmark our algorithm with three common problems in topology optimization. High resolution three-dimensional design models optimized for arbitrary cost and constraint functions are absolutely necessary ingredients for the solution of real{world engineering design problems. However, such requirements are non trivial to implement. In this thesis, we address this dilemma by developing a large scale topology optimization framework with AMR. We discuss the need for efficient parallelizable regularization methods that work across different mesh resolutions, iterative solvers and data structures. Furthermore, the optimization algorithm needs to be implemented with the same data structure that is used for the design field. To demonstrate the versatility of our framework, we optimize the designs of a three dimensional stress constrained benchmark L-bracket and a stress-constrained compliant mechanism

    Vesicular-arbuscular mycorrhizal, dark septate endophytes and root anatomy in Fragaria ananassa var. Camino Real (Rosaceae) in the province of Tucumán, Argentina

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    En la provincia de Tucumán el cultivo de frutilla ocupa una superficie de 350 hectáreas. El mismo es invernal, con cosechas periódicas de fines de mayo a noviembre inclusive. Para evitar esta discontinuidad de producción, se incorporan al espectro de variedades precoces (Fortuna y Festival), variedades tardías, entre ellas Camino Real. Los objetivos de este trabajo fueron estudiar las micorrizas vesículo-arbusculares, los endófitos septados oscuros y caracterizar la anatomía radical en Fragaria ananassa var. Camino Real en cultivo comercial en la provincia de Tucumán. El muestreo fue realizado en el INTA-EEA Famaillá, Tucumán, Argentina. Se recolectaron los sistemas radicales correspondientes a un total de 20 individuos; los que fueron tratados con técnicas convencionales. Los sistemas radicales de la variedad Camino Real presentan las células del parénquima cortical colonizadas por micorrizas vesículo-arbusculares con dos tipos morfológicos simultáneos: Arum y Paris, siendo la morfología Arum la de mayor frecuencia. Además, el tejido cortical presenta endófitos septados oscuros. La anatomía radical de la estructura primaria presenta una histología típica con estelas de tipo diarca a tetrarca. Mientras que la estructura secundaria de la raíz muestra diferentes estadios de crecimiento, con restos de epidermis y parénquima cortical adheridos a la polidermis en formación. Se describen por primera vez, para Argentina, las micorrizas vesículoarbusculares, los endófitos septados oscuros y la anatomía radical en Fragaria ananassa var. Camino Real.In the province of Tucumán strawberry cultivation occupies an area of 350 hectares. It is a winter crop, with periodic harvests since late May to November inclusive. To avoid this discontinuity of production, a late variety (Camino Real) was added to the spectrum of early varieties (Fortuna and Festival). This paper aims to evaluate the vesicular-arbuscular mycorrhiza, dark septate endophytes and characterize the radical anatomy in Fragaria ananassa variety Camino Real in the province of Tucumán. The sampling was carried out at INTA-EEA Famaillá, Tucumán, Argentina. The radicals systems corresponding to 20 individuals were collected and treated with conventional techniques. The root systems of the variety Camino Real, show cortical parenchyma cells colonized by vesicular-arbuscular mycorrhizae which have two simultaneous morphological types: Arum and Paris. The Arum morphology is the most frequent. In addition, the cortical tissue has dark septate endophytes. The radical anatomy of the primary structure presents a typical histology with diarca to tetrarch stela, while the secondary root structure show different stages of growth with traces of epidermis and cortical parenchyma attached to the polidermis in development. The vesicular-arbuscular mycorrhizae, dark septate endophytes and radical anatomy of Fragaria ananassa var. ‘Camino Real’ were described for the first time for ArgentinaFil: Lizarraga, Sofía Valentina. Fundación Miguel Lillo; ArgentinaFil: Ruiz, A. I.. Fundación Miguel Lillo; ArgentinaFil: Salazar, Sergio Miguel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; Argentina. Instituto Nacional de Tecnología Agropecuaria; ArgentinaFil: Diaz Ricci, Juan Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaFil: Albornoz, Patricia Liliana. Fundación Miguel Lillo; Argentin

    The effect of broadband matching in simultaneous information and power transfer

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    This paper presents the implementation and the effect of broadband matching in simultaneous information and power transfer. The narrowband characteristic of antennas limited the applications of simultaneous information and power transfer. The simplified real frequency technique (SRFT) and the non-foster matching technique have been presented to improve the performance in terms of channel capacity and power delivery. Electromagnetic simulation and multiobjective optimization are performed to analyze the tradeoff between the channel capacity and power delivery in different matching conditions. The performance gain using the matching networks have been demonstrated and analyzedPeer ReviewedPostprint (author’s final draft
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