508 research outputs found
Vertical wind profile characterization and identification of patterns based on a shape clustering algorithm
Wind power plants are becoming a generally accepted resource in the generation mix of many utilities. At the same time, the size and the power rating of individual wind turbines have increased considerably. Under these circumstances, the sector is increasingly demanding an accurate characterization of vertical wind speed profiles to estimate properly the incoming wind speed at the rotor swept area and, consequently, assess the potential for a wind power plant site. The present paper describes a shape-based clustering characterization and visualization of real vertical wind speed data. The proposed solution allows us to identify the most likely vertical wind speed patterns for a specific location based on real wind speed measurements. Moreover, this clustering approach also provides characterization and classification of such vertical wind profiles. This solution is highly suitable for a large amount of data collected by remote sensing equipment, where wind speed values at different heights within the rotor swept area are available for subsequent analysis. The methodology is based on z-normalization, shape-based distance metric solution and the Ward-hierarchical clustering method. Real vertical wind speed profile data corresponding to a Spanish wind power plant and collected by using a commercialWindcube equipment during several months are used to assess the proposed characterization and clustering process, involving more than 100000 wind speed data values. All analyses have been implemented using open-source R-software. From the results, at least four different vertical wind speed patterns are identified to characterize properly over 90% of the collected wind speed data along the day. Therefore, alternative analytical function criteria should be subsequently proposed for vertical wind speed characterization purposes.The authors are grateful for the financial support from the Spanish Ministry of the Economy and Competitiveness and the European Union —ENE2016-78214-C2-2-R—and the Spanish Education, Culture and Sport Ministry —FPU16/042
Influence of irrigation conditions in the germination of plasma treated Nasturtium seeds
Plasma treatments had emerged as a useful technique to improve seed germination. In this work we investigate the influence of different irrigation conditions and plasma treatments on the germination of nasturtium seeds. During plasma treatment, seeds experience a progressive weight loss as a function of treatment time that has been associated to water release, a process that is more pronounced after longer plasma treatment times. Seeds treated for short times (<30 s) are able to germinate more efficiently than untreated specimen under hydric stress (drought conditions), while plasma treatments for longer times (up to 300 s) impaired germination independently on irrigation conditions. Characterization analysis of plasma treated seeds by FTIR-ATR, SEM/EDX and XPS showed that plasma treatment affected the chemical state of pericarp while, simultaneously, induced a considerable increase in the seeds water uptake capacity. The decrease in germination efficiency found after plasma treatment for long times, or for short times under optimum irrigation conditions, has been attributed to that the excess of water accumulated in the pericarp hampers the diffusion up to the embryo of other agents like oxygen which are deemed essential for germination.España FEDER y MINECO MINECO (projects MAT2013-40852-R, MAT2016-79866-R, MINECOCSIC 201560E055)España, RECUPERA 2020 y Junta de Andalucía project P12-2265 M
Effect of Preoperative Infusion of Levosimendan on Biomarkers of Myocardial Injury and Haemodynamics After Paediatric Cardiac Surgery: A Randomised Controlled Trial
Trial registry number: EudraCT 2012-005310-19.Key Points
A randomised controlled trial was conducted to test the hypothesis that preoperative infusion of levosimendan would decrease myocardial injury biomarkers (troponin I and B-type natriuretic peptide) after paediatric cardiac surgery more efficiently than placebo.
Troponin I and B-type natriuretic peptide levels were higher with placebo at 12 and 24 h after cardiopulmonary bypass, but the differences were not statistically significant. Lactic acid level was significantly lower and oxygen delivery (DO2) was significantly higher at 12 and 24 h after surgery in Levosimendan group.
The results highlight the importance of this new drug and its possible benefit with regard to myocardial injury; however, evaluation in larger, adequately powered trials is needed to determine the efficacy of levosimendan.Objective
The aim was to test the hypothesis that preoperative infusion of levosimendan would decrease patients’ cardiac biomarker profiles during the immediate postoperative stage (troponin I and B-type natriuretic peptide levels) more efficiently than placebo after cardiopulmonary bypass.
Methods
In a randomised, placebo-controlled, double-blinded study, 30 paediatric patients were scheduled for congenital heart disease surgery. 15 patients (50%) received prophylactic levosimendan and 15 patients (50%) received placebo from 12 h before cardiopulmonary bypass to 24 h after surgery.
Results
Troponin I levels were higher in the placebo group at 0, 12, and 24 h after cardiopulmonary bypass, although the mean differences between the study groups and the 95% confidence intervals (CIs) for troponin I levels did not present statistically significant differences at any of the three time points considered (mean differences [95% CIs] − 3.32 pg/ml [− 19.34 to 12.70], − 2.42 pg/ml [− 19.78 to 13.95], and − 79.94 pg/ml [− 266.99 to 16.39] at 0, 12, and 24 h, respectively). A similar lack of statistically significant difference was observed for B-type natriuretic peptide (mean differences [95% CIs] 36.86 pg/dl [− 134.16 to 225.64], − 350.79 pg/dl [− 1459.67 to 557.45], and − 310.35 pg/dl [− 1505.76 to 509.82]). Lactic acid levels were significantly lower with levosimendan; the mean differences between the study groups and the 95% CIs for lactate levels present statistically significant differences at 0 h (− 1.52 mmol/l [− 3.19 to − 0.25]) and 12 h (− 1.20 mmol/l [− 2.53 to − 0.10]) after cardiopulmonary bypass. Oxygen delivery (DO2) was significantly higher at 12 h and 24 h after surgery (mean difference [95% CI] 627.70 ml/min/m2 [122.34–1162.67] and 832.35 ml/min/m2 [58.15 to 1651.38], respectively).
Conclusions
Levosimendan does not significantly improve patients’ postoperative troponin I and B-type natriuretic peptide profiles during the immediate postoperative stage in comparison with placebo, although both were numerically higher with placebo. Levosimendan, however, significantly reduced lactic acid levels and improved patients’ DO2 profiles. These results highlight the importance of this new drug and its possible benefit with regard to myocardial injury; however, evaluation in larger, adequately powered trials is needed to determine the efficacy of levosimendan
META 2016
Producción CientíficaA planar complementary metamaterial, as well as its corresponding inverse structure, has been designed and characterized. Numerical results (using commercial software) are presented here. The structure shows a giant gyrotropy (chirality) as well as very low losses.Ministerio de Economía, Industria y Competitividad (Project TEC2014-55463-C3-2-P
A complementary chiral metamaterial with giant electromagnetic activity and low losses
A planar complementary metamaterial, as well as its corresponding inverse structure, has been designed and characterized. Numerical results (using commercial software) are presented here. The structure shows a giant gyrotropy (chirality) as well as very low losses.This work has been supported by the Spanish Government (MINECO) through the Research Projects TEC2014-55463-C3-1-P, TEC2014-55463-C3-2-P, and TEC2014-55463-C3-3-P and also by the European Commission (ERDF)
El pensamiento médico social de Ernesto Guevara: su presencia en el paradigma socio-médico cubano
La personalidad de Ernesto Guevara es reconocida en el mundo por sus aportes a la lucha de los pueblos, su ética y sus principios revolucionarios, que han dejado sus huellas en la vida social, política, económica y cultural de las diferentes naciones del mundo; sin embargo, un aspecto insuficientemente estudiado de su obra es su pensamiento y acciones a favor del desarrollo de la medicina social, aquella que le otorga un papel determinante a los factores sociales en el origen y desarrollo de la salud y la enfermedad, así como a la acción político - gubernamental en las áreas de prevención, promoción, rehabilitación y a la atención médica. Estas ideas del Che se fueron conformando a lo largo de su vida, mucho antes de iniciar su carrera como médico, y se consolidaron durante la lucha guerrillera en la Sierra Maestra; se convirtieron en convicción en su actuar práctico, primero, durante la lucha revolucionaria, y después del triunfo en 1959 en Cuba. En el pensamiento médico social de Che están contenidos los principios rectores y las bases conceptuales y prácticas del paradigma socio-médico cubano, que están vigentes en la concepción de la medicina familiar y en la formación del médico de familia cubano. Este trabajo tiene como objetivo determinar los principales aspectos del pensamiento médico social de Ernesto Che Guevara y su contribución teórica a la conformación del paradigma socio-médico cubano
Evolución Reciente del Endeudamiento Externo de los Bancos Colombianos - Marzo de 2021
El objetivo de este informe es describir la evolución reciente de las líneas de crédito en moneda extranjera de los bancos colombianos y presentar los principales resultados de la última encuesta de endeudamiento externo y cupos, la cual fue aplicada por el Departamento de Estabilidad Financiera del Banco de la República a una muestra representativa de bancos comerciales que tienen líneas de crédito en moneda extranjera
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