Browsing by Author "Cordova, Samuel"

Now showing 1 - 15 of 15
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    An Efficient Forecasting-Optimization Scheme for the Intraday Unit Commitment Process Under Significant Wind and Solar Power
    (2018) Cordova, Samuel; Rudnick, Hugh; Lorca Galvez, Álvaro Hugo; Martinez Aranza, Victor Julio
    Due to their uncertain and variable nature, the large-scale integration of wind and solar power poses significant challenges to the generator scheduling process in power systems. To support this process, system operators require using repeatedly updated forecasts of the best possible quality for renewable power. Motivated by this, the present work aims to study the benefits of incorporating spatiotemporal dependence and seasonalities into probabilistic forecasts for the intraday unit commitment (UC) process. With this purpose, a highly efficient forecasting-optimization scheme is proposed, which is composed of a detrended periodic vector autoregressive model and a technology-clustered interval UC model. The proposed approach is tested on a 120-GW power system with 210 conventional generators using real wind and solar measurements and compared to existing deterministic and stochastic UC techniques alongside standard forecasting methods. Extensive computational experiments show that the incorporation of spatiotemporal dependence and seasonalities into forecasts translates in a reduction of up to 1.55% in operational costs for a daily UC relative to standard practice, the application of intraday instead of daily UC runs further reduces operational costs in up to 1.51%, and the proposed forecasting-optimization scheme takes less than 10 h to simulate a whole year.
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    Aporte de la ecocardiografía tridimensional en el diagnóstico y manejo de la endocarditis infecciosa. Experiencia clínica
    (2017) Vega, Julián; Gabrielli, Luigi; Cordova, Samuel; Muñoz Contreras, María Cecilia; Mc-Nab Martin, Paul Andrew; Saavedra Madariaga, Rodrigo Alejandro; Zalaquett Sepúlveda, Ricardo
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    Big thrombus "sitting" in an atrial septal aneurysm
    (2017) Vega, Julián; Gabrielli, Luigi; Cordova, Samuel; Saavedra Madariaga, Rodrigo Alejandro; Mc-Nab Martin, Paul Andrew
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    Cambios agudos en la función auricular derecha post uso de iloprost inhalatorio en pacientes con hipertensión arterial pulmonar : estudio con técnicas de deformación de imagen
    (2015) Kanacri, Andres; Gabrielli, Luigi; Vega, Julián; Saavedra Madariaga, Rodrigo Alejandro; Cordova, Samuel; Sepulveda, Pablo; Castro Gálvez, Pablo Federico
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    Endocarditis infecciosa por Listeria monocytogenes: revisión de la literatura a partir de un caso clínico
    (2013) Marin, Arnaldo; Lustig, Nicole; Cruz Urrutia, Ricardo Javier; Cordova, Samuel
    Infective endocarditis caused by Listeria monocytogenes is an extremely rare but usually aggressive disease. We have seen in recent years an increase in age of onset of this disease and a predilection for patients With valvular disease, especially prosthetic valve. The treatment of choice is ampicillin, which is combined with gentamicin for synergy. It is known that even with treatment the Mortality is very high and higher than in other types of bacterial endocarditis. With optimal therapy, that is medical-surgical, mortality has declined significantly in recent years. We presents a review of literature and a clinical ease of a patient with a febrile syndrome diagnosed as a infective endocarditis caused by L. monocytogenes treated Medically with successful Outcome to date.
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    Hipertrofia ventricular izquierda con patrón de strain característico. Left ventricular hypertrophy with a characteristic strain pattern
    (2017) Vega, Julián; Cordova, Samuel; Gabrielli, Luigi; Mc-Nab Martin, Paul Andrew; Saavedra Madariaga, Rodrigo Alejandro
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    Increased Rho-Kinase Activity in Hypertensive Patients With Left Ventricular Hypertrophy
    (2014) Gabrielli, Luigi; Winter, J.; Godoy J., Iván; Mc-Nab Martin, Paul Andrew; Padilla Argote, Ivonne Evelyn; Cordova, Samuel; Rigotti, P.; Novoa, Ulises; Mora, I.; Garcia, L.; Ocaranza Jeraldino, M. Paz; Jalil Milad, Jorge; Gabrielli, Luigi; Winter, J.; Godoy J., Iván; Mc-Nab Martin, Paul Andrew; Padilla Argote, Ivonne Evelyn; Cordova, Samuel; Rigotti, P.; Novoa, Ulises; Mora, I.; Garcia, L.; Ocaranza, María Paz; Jalil Milad, Jorge
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    Insuficiencia aórtica sistólica, un fenómeno singular
    (2017) Vega, Julián; Cordova, Samuel; Gabrielli, Luigi; Saavedra Madariaga, Rodrigo Alejandro; Mc-Nab Martin, Paul Andrew
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    Left Atrial Dysfunction Is a Predictor of Postcoronary Artery Bypass Atrial Fibrillation: Association of Left Atrial Strain and Strain Rate Assessed by Speckle Tracking
    (WILEY, 2011) Gabrielli, Luigi; Corbalan, Ramon; Cordova, Samuel; Enriquez, Andres; Mc Nab, Paul; Verdejo, Hugo E.; Godoy, Ivan; Zalaquett, Ricardo; Lavandero, Sergio
    Background: Even though atrial fibrillation (AF) is the most common arrhythmia after coronary artery bypass grafting (CABG), its etiology remains poorly understood. Several factors are linked to postoperative AF (POAF), including advanced age and systemic inflammation. However, left atrial (LA) contractile dysfunction has not been evaluated in the perioperative scenario. Aim: To evaluate LA function through strain and strain rate in patients with coronary artery disease undergoing CABG and its correlation with POAF. Methods: We studied 70 patients undergoing CABG in sinus rhythm at the time of surgery. Preoperative echocardiography with evaluation of LA strain and strain rate by speckle tracking was performed. The occurrence of POAF was evaluated by continuous monitoring. Baseline and postoperative C-reactive protein (CRP) levels were measured to evaluate systemic inflammation. Results: After 1-week follow-up 26% of subjects developed AF. LA strain s wave (LASs) and LA strain rate s (LASRs) and a wave (LASRa) were significantly decreased in patients who developed POAF: LASs (10 +/- 1% vs. 24 +/- 1%, P < 0.001), LASRs (0.6 +/- 0.1 sec1 vs. 1.2 +/- 0.1 sec-1, P < 0.001), LASRa (-0.6 +/- 0.1 sec1 vs. 1.8 +/- 0.1 sec-1, P < 0.001). LASRs, LASRa, age, and LA volume were independent predictors of POAF. CRP at baseline was similar irrespective of POAF development. Conclusions: LA dysfunction, evaluated by strain and strain rate is an independent predictor of POAF and contributes to classic risk factors like age and atrial volume. (Echocardiography 2011;28:1104-1108)
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    Markedly increased Rho-kinase activity in circulating leukocytes in patients with chronic heart failure
    (MOSBY-ELSEVIER, 2011) Paz Ocaranza, Maria; Gabrielli, Luigi; Mora, Italo; Garcia, Lorena; McNab, Paul; Godoy, Ivan; Braun, Sandra; Cordova, Samuel; Castro, Pablo; Novoa, Ulises; Chiong, Mario; Lavandero, Sergio; Jalil, Jorge E.
    Background The small guanosine triphosphatase Rho and its target Rho-kinase have significant roles in experimental remodeling and ventricular dysfunction, but no data are available on Rho-kinase activation in patients with heart failure (HF). We hypothesized that, in patients with chronic HF, Rho-kinase in circulating leukocytes is activated and related to left ventricular (LV) remodeling and dysfunction.
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    Reparación de una perforación valvular mitral como secuela de endocarditis, aporte de la ecocardiografía tridimensional
    (2016) Vega, Julián; Cordova, Samuel; Muñoz, M. C.; Gabrielli, Luigi; Mc-Nab Martin, Paul Andrew; Saavedra Madariaga, Rodrigo Alejandro
    Resumen Reportamos un caso de reparación de perforación valvular mitral en un joven de 18 años que consulta por disnea de esfuerzos y con el antecedente remoto de una artritis séptica de rodilla tratada. En el examen físico se encontró un soplo holosistólico 4/6 en el foco mitral. Se realizó un ecocardiograma transtorácico (ETT) que objetivó una insuficiencia mitral severa, con un jet de recorrido muy excéntrico originado desde anterior, sospechando una perforación del velo anterior, sin lograr caracterizarla por dicha técnica. Se complementó el estudio con un ecocardiograma transesofágico (ETE) en una plataforma EPIQ 7 cv (PHILIPS), que identificó en el cuerpo del segmento 2 del velo anterior mitral (A2) una posible perforación. El análisis de la válvula mediante ETE tridimensional (3D), confirmó una perforación circular de bordes netos, de dimensiones máximas 6x6 mm, localizada en el cuerpo de A2. El análisis 3D aportó valiosa información para programar la reparación valvular, la cual se efectuó mediante un parche de pericardio autólo-go fresco (sin fijación en glutaraldehido) y una anu-loplastía con un anillo rígido, con óptimo resultado y sin complicaciones.
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    Resultados a largo plazo de la valvuloplastía mitral con balón
    (2014) Martínez, Gonzalo; Fajuri, Alejandro; Cordova, Samuel; Braun Jones, Sandra; Marchant, Eugenio; Guarda, E.; Veas, N.; Méndez Lesser, Manuel; Lindefjeld, Dante; Pérez, Osvaldo; Flores, A.; Valenzuela, E.|Martínez, A.
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    Rho-kinase pathway activation and apoptosis in circulating leucocytes in patients with heart failure with reduced ejection fraction
    (2020) Ocaranza, María Paz; Moya, J; Jalil Milad, Jorge; Lavandero, S; Kalergis Parra, Alexis Mikes; Molina, C; Gabrielli, Luigi; Godoy J., Iván; Cordova, Samuel; Castro Gálvez, Pablo Federico; Mac Nab, P; Rossel, V; Garcia, L; Gonzalez, J; Mancilla, C; Fierro, C; Farias, L
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    Veinte años de cirugía reparadora de la válvula mitral
    (2014) Zalaquett Sepúlveda, Ricardo; Latorre, G.; Almeida, J.; Meneses, A.; Muñoz Contreras, María Cecilia; Cordova, Samuel