1,439 research outputs found

    Impact of Fluid Substitution on the Performance of an Axial Compressor Blade Cascade Working with Supercritical Carbon Dioxide

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    Abstract Recent research on turbomachinery design and analysis for supercritical carbon dioxide (sCO2) power cycles has relied on computational fluid dynamics. This has produced a large number of works whose approach is mostly case-specific, rather than of general application to sCO2 turbomachinery design. As opposed to such approach, this work explores the aerodynamic performance of compressor blade cascades operating on air and supercritical CO2 with the main objective to evaluate the usual aerodynamic parameters of the cascade for variable boundary conditions and geometries, enabling “full” or “partial” similarity. The results present both the global performance of the cascades and certain features of the local flow (trailing edge and wake). The discussion also highlights the mechanical limitations of the analysis (forces exerted on the blades), which is the main restriction for applying similarity laws to extrapolate the experience gained through decades of work on air turbomachinery to the new working fluid. This approach is a step toward the understanding and appropriate formulation of a multi-objective optimization problem for the design of such turbomachinery components where sCO2 is used as the operating fluid. With this objective, the paper aims to identify and analyze what would be expected if a common description of such computational design problems similar to those where air is the working fluid were used.</jats:p

    Comentarios sobre el discurso quĂ­mico en la escuela

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    Este libro presenta los resultados de la experiencia de formación de profesores llevada a cabo desde el campo de la química en el marco del Programa RED de la Universidad Nacional de Colombia. / Contenido. Preliminares; Capítulo 1 - La experiencia; Capítulo 2 - Demostraciones y enseñanza de la química; Anexos

    Radical radiotherapy in epidermoid cancer in the orbitary region: ideal scheme of hypo-fractionation in times of COVID-19: a case report

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    There are adverse events in the patient's environment that impact on therapeutic decisions and become a medical challenge, as is currently the management of cancer patients with radiotherapy, particularly the elderly in times of a COVID-19 pandemic, due the high risk of infection and fatal complications from non-cancer causes. Here we present the case of an 84-year-old woman with voluminous squamous cell cancer in the left orbital region, which caused intense pain, stench, and persistent bleeding. And due to persistence and time, it impacted with deterioration in the patient’s quality of life. In the end, of hypo fractionated radiotherapy management as the only modality, it evolves with a complete clinical response and total palliation of initial symptoms. The reasons for the decision to manage radiotherapy and the excellent clinical results that reinforce the idea of personalized medicine and the importance of evaluating the biopsychosocial environment of the cancer patient will be discussed

    Physical capacity in youth football players of a profesional club

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    Las caracterĂ­sticas fĂ­sicas del fĂștbol son muy diversas, aunque se reconocen como muy importantes la capacidad de realizar esfuerzos de alta intensidad y la de retrasar la fatiga en la mayor medida posible en esfuerzos intermitentes. Son diversos los trabajos que analizan dichas caracterĂ­sticas en el fĂștbol profesional, aunque son menores los que analizan las categorĂ­as de formaciĂłn. En el presente estudio se analiza la evoluciĂłn por categorĂ­as de pruebas de salto, velocidad, agilidad y resistencia aerĂłbica especĂ­fica, en jugadores de fĂștbol jĂłvenes de la cantera de un club profesional de la liga española. Se produjo un incremento de las marcas con la edad, aunque no se observaron diferencias significativas en grupos de edad cercanos, produciĂ©ndose una meseta en el rendimiento en la fuerza explosiva y velocidad de aceleraciĂłn a partir de los 17 años y en la velocidad de desplazamiento y agilidad a los 15 añosPhysical characteristics of football are very different, but are recognized as very important the ability to perform high-intensity efforts and to delay fatigue as much as possible in intermittent efforts. There are several studies that analyze these characteristics in professional football but are less those who analyze the categories of training. In the present study analyzes the evolution of categories of jumping, speed, agility and specific endurance in young soccer players from a professional club of the Spanish league. There was an increase of the marks with age, although no significant differences in age groups encircle. Producing a plateau in performance in explosive strength and acceleration speed from 17 years and in speed and agility at age of 1

    Antimicrobial Resistance in Bacteria Isolated from Exotic Pets : The Situation in the Iberian Peninsula

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    Literature related to antimicrobial resistant (AMR) bacteria in exotic pets is minimal, being essential to report objective data on this topic, which represents a therapeutic challenge for veterinary medicine and public health. Between 2016 and 2020, laboratory records of 3156 exotic pet specimens' microbiological diagnoses and antibiotic susceptibility testing (AST) results were examined. The samples were classified into three animal classes: birds (n = 412), mammalia (n = 2399), and reptilian (n = 345). The most prevalent bacteria in birds and mammals were Staphylococcus spp. (15% and 16%), while in reptiles they were Pseudomonas spp. (23%). Pseudomonas was the genus with the highest levels of AMR in all animal groups, followed by Enterococcus spp. By contrast, Gram-positive cocci and Pasteurella spp. were the most sensitive bacteria. Moreover, in reptiles, Stenotrophomonas spp., Morganella spp., and Acinetobacter spp. presented high levels of AMR. Multidrug-resistant (MDR) bacteria were isolates from reptiles (21%), birds (17%), and mammals (15%). The Enterobacterales had the highest MDR levels: S. marcescens (94.4%), C. freundii (50%), M. morganii (47.4%), K. pneumoniae (46.6%), E. cloacae (44%), and E. coli (38.3%). The prevalence of MDR P. aeruginosa strains was 8%, detecting one isolate with an XDR profile. Regarding antimicrobial use, many antibiotics described as critically important for human use had significant AMR prevalence in bacteria isolated from exotic pets. Under the One-Health approach, these results are alarming and of public health concern since potential transmission of AMR bacteria and genes can occur from exotic pets to their owners in both senses. For this reason, the collaboration between veterinarians and public health professionals is crucial

    Urban sustainability. Tome: A proposal for evaluating chilean general plans

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    This article values the sustainability in the urban planning through the design of an indicators system, that arise from the identification of the attributes of the Sustainable Urban Planning. The indicators are tried in the proposed land cover model established in the instrument of territorial planning called “Regulator Urban Plan”. The study is applied in the town of “TomĂ©â€, located in the 8th Region “BĂ­o BĂ­o” of Chile. The obtaining of the indicators of urban sustainability is developed from the use of the tools of GIS. The proposed urban planning is evaluated with a system of indicators based on 3 territorial components, that are: Distribution of uses and physical structure, Land use consumption and environmental Quality, and are processed in the zones of the proposed land cover model. The method combines the bibliographical analysis with the application of spatial analysis and geoprocessing in GIS. The results allow to access to us to value the sustainability of the proposed territorial model.Este artĂ­culo valora la sostenibilidad en la planificaciĂłn urbana por medio del diseño de un sistema de indicadores, que surgen de la identificaciĂłn de los atributos del Planeamiento Urbano Sostenible. Los indicadores se ensayan en el modelo de ocupaciĂłn del suelo propuesto y establecido en el instrumento de planificaciĂłn territorial denominado "Plan Regulador Comunal". El estudio se aplica en la localidad de TomĂ©, ubicada en la VIII RegiĂłn del Bio BĂ­o de Chile. La obtenciĂłn de los indicadores de sostenibilidad urbana se desarrolla a partir del uso de las herramientas de Sistemas de InformaciĂłn GeogrĂĄfica Ăł SIG. El planeamiento urbano propuesto se evalĂșa con un sistema de indicadores basados en 3 componentes territoriales que se procesan en la zonficaciĂłn del suelo urbano propuesto y que son, la distribuciĂłn de usos y estructura fisica, el consumo de Suelo y la calidad ambiental. El mĂ©todo combina el analisis bibliogrĂĄfico, con la aplicaciĂłn de anĂĄlisis espacial y geoprocesamiento en SIG. Los resultados se aproximan a valorar la sostenibilidad del modelo territorial propuesto

    NIVELES DE VIBRACIONES EN LA CIUDAD DE PANAMÁ

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    &nbsp; &nbsp;This paper studies the levels of maximum accelerations of the ambient vibrations and their corresponding frequencies in a sector of Panama City, which concentrates health centers educational, religious and residential buildings. The measurements were due during a year in 25 points, three times a day was possible to verify that we are exposed to high levels dose of vibrations that, although in most of the cases are not perceivable, they affect in the long term.&nbsp;&nbsp; &nbsp;En este trabajo se estudian los niveles de aceleraciones måximas de las vibraciones ambientales y sus correspondientes frecuencias, en un sector de la Ciudad de Panamå que concentra centros sanitarios, educativos y religiosos, así como edificios residenciales. Las mediciones se realizaron durante un año, en 25 puntos de la ciudad, en tres momentos del día. Se pudo comprobar que estamos expuestos a niveles de vibraciones altas que, aunque en la mayoría de los casos no son perceptibles por las personas, afectan nuestra salud.&nbsp

    Quinoa in Ecuador: Recent Advances under Global Expansion

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    Quinoa is a highly diverse crop domesticated in the Andean region of South America with broad adaptation to a wide range of marginal environments. Quinoa has garnered interest worldwide due to its nutritional and health benefits. Over the last decade, quinoa production has expanded outside of the Andean region, prompting multiple studies investigating the potential for quinoa cultivation in novel environments. Currently, quinoa is grown in countries spanning five continents, including North America, Europe, Asia, Africa, and Oceania. Here, we update the advances of quinoa research in Ecuador across different topics, including (a) current quinoa production situation with a focus on breeding progress, (b) traditional seed production, and (c) the impact of the work of the nongovernment organization “European Committee for Training and Agriculture” with quinoa farmers in Chimborazo province. Additionally, we discuss genetic diversity, primary pests and diseases, actions for adapting quinoa to tropical areas, and recent innovations in quinoa processing in Ecuador. Finally, we report a case study describing a participatory breeding project between Washington State University and the Association of Andean Seed and Nutritional Food Producers Mushuk Yuyay in the province of Cañar

    Unexplored outflows in nearby low luminosity AGNs: the case of NGC 1052

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    Outflows play a central role in galaxy evolution shaping the properties of galaxies. Understanding outflows and their effects in low luminosity AGNs, such as LINERs, is essential (e.g. they are a numerous AGN population in the local Universe). We obtained VLT/MUSE and GTC/MEGARA optical IFS-data for NGC1052, the prototypical LINER. The stars are distributed in a dynamically hot disc, with a centrally peaked velocity dispersion map and large observed velocity amplitudes. The ionised gas, probed by the primary component is detected up to ∌\sim30arcsec (∌\sim3.3 kpc) mostly in the polar direction with blue and red velocities (∣\midV∣\mid<<250 km/s). The velocity dispersion map shows a notable enhancement (σ\sigma>>90 km/s) crossing the galaxy along the major axis of rotation in the central 10arcsec. The secondary component has a bipolar morphology, velocity dispersion larger than 150 km/s and velocities up to 660 km/s. A third component is detected but not spatially resolved. The maps of the NaD absorption indicate optically thick neutral gas with a velocity field consistent with a slow rotating disc (Δ\DeltaV = 77±\pm12 km/s) but the velocity dispersion map is off-centred without any counterpart in the flux map. We found evidence of an ionised gas outflow with mass of 1.6±\pm0.6 ×\times 105^{5} Msun, and mass rate of 0.4±\pm0.2 Msun/yr. The outflow is propagating in a cocoon of gas with enhanced turbulence and might be triggering the onset of kpc-scale buoyant bubbles (polar emission). Taking into account the energy and kinetic power of the outflow (1.3±\pm0.9 ×\times 1053^{53} erg and 8.8±\pm3.5 ×\times 1040^{40} erg/s, respectively) as well as its alignment with both the jet and the cocoon, and that the gas is collisionally ionised, we consider that the outflow is jet-powered, although some contribution from the AGN is possible.Comment: A&A accepted 04/04/2022, 31 pages, 12 figures and 3 appendixe

    Vitamin D Deficiency Is Significantly Associated with Retinopathy in Type 2 Diabetes Mellitus: A Case-Control Study

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    Aim: Results from meta-analyses point to an association between vitamin D deficiency and the onset of diabetic retinopathy (DR). The objectives of the present study were to evaluate the association of vitamin D for the development of DR and to determine the levels of vitamin D associated with a greater risk of DR. Methods: Between November 2013 and February 2015, we performed a case-control study based on a sample of patients with diabetes in Spain. The study population comprised all patients who had at least one evaluable electroretinogram and recorded levels of 25(OH)D. We collected a series of analytical data: 25(OH)D, 1,25(OH)2D, iPTH, calcium, albumin, and HbA1c. Glycemic control was evaluated on the basis of the mean HbA1c values for the period 2009?2014. A logistic regression analysis was performed to identify the variables associated with DR. Results: The final study sample comprised 385 patients, of which 30 (7.8%) had DR. Significant differences were found between patients with and without DR for age (69.54 vs. 73.43), HbA1c (6.68% vs. 7.29%), years since diagnosis of diabetes (10.9 vs. 14.17), level of 25(OH)D (20.80 vs. 15.50 ng/mL), level of 1,25(OH)2D (35.0 vs. 24.5 pg/mL), treatment with insulin (14.9% vs. 56.7%), hypertension (77.7% vs. 100%), cardiovascular events (33.2% vs. 53.3%), and kidney failure (22.0% vs. 43.3%). In the multivariate analysis, the factors identified as independent risk factors for DR were treatment of diabetes (p = 0.001) and 25(OH)D (p = 0.025). The high risk of DR in patients receiving insulin (OR 17.01) was also noteworthy. Conclusions: Levels of 25(OH)D and treatment of diabetes were significantly associated with DR after adjusting for other risk factors. Combined levels of 25(OH)D < 16 ng/mL and levels of 1,25(OH)2D < 29 pg/mL are the variables that best predict the risk of having DR with respect to vitamin D deficiency. The risk factor with the strongest association was the treatment of type 2 diabetes mellitus. This was particularly true for patients receiving insulin, who had a greater risk of DR than those receiving insulin analogues. However, further studies are necessary before a causal relationship can be established
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