Control adaptativo por modelo de referencia para un inversor basado en LCL con síntesis de controlador mínima

[Resumen] Un Control Adaptativo por Modelo de Referencia (MRAC) con Síntesis de Controlador Mínima (MCS), es desarrollado con el objetivo de controlar un Inversor monofásico basado en un Filtro LCL conectado a la Red Eléctrica y adaptar el inductor de la red, que es un parámetro desconocido y que genera incertidumbre, manteniendo las prestaciones y la robustez del sistema. Para ello primero se revisara el algoritmo de MCS y en función de este, se muestran todos los pasos a seguir y el desarrollo de los componentes necesarios para el funcionamiento de MCS en tiempo continuo. Se desarrolla un modelo de simulación promediado y se presentan los resultados obtenidos.Este trabajo ha sido realizado gracias al apoyo de la Secretaría Nacional de Educación Superior, Ciencia y Tecnología e Innovación del Ecuador (SENESCYT), a la Universidad de Cuenca, y a los proyectos DPI2013-41224-P y DPI2015-69286-C3-2-R (MINECO/FEDER) y 2014 SGR 267 de la agencia AGAUR de la Generalitat de CatalunyaGeneralitat de Catalunya; 2014 SGR 267https://doi.org/10.17979/spudc.978849749808

Mental health and burnout syndrome among postgraduate students in medical and multidisciplinary residencies during the COVID-19 pandemic in Brazil : protocol for a prospective cohort study

Background: The COVID-19 pandemic has led to high levels of physical, psychological, and social stress among health care professionals, including postgraduate students in medical and multidisciplinary residencies. This stress is associated with the intense fear of occupational exposure to SARS-CoV-2, the virus known to cause COVID-19. These professionals are at risk of developing physical and mental illnesses not only due to the infection but also due to prolonged exposure to multidimensional stress and continued work overload. Objective: This study aims to evaluate the prevalence of symptoms suggestive of mental disorders and burnout syndrome and determine the risk factors for burnout among postgraduate students in medical and multidisciplinary residencies in Brazil during the COVID-19 pandemic. Methods: For this prospective cohort study with parallel groups, participants were recruited between July and September 2020 to achieve a sample size of at least 1144 participants. Research instruments such as Depression, Anxiety, and Stress Scale; Patient Health Questionnaire; Brief Resilient Coping Scale; and Oldenburg Burnout Inventory will be used to collect data. Data will be collected in 2 waves: the first wave will include data related to sample characterization and psychosocial evaluation, and the second wave will be launched 12 weeks later and will include an evaluation of the incidence of burnout as well as correlations with the potential predictive factors collected in the first wave. Additionally, we will collect data regarding participants’ withdrawal from work. Results: The recruitment took place from July 29 to September 5, 2020. Data analyses for this phase is already in progress. The second phase of the study is also in progress. The final data collection began on December 1, 2020, and it will be completed by December 31, 2020. Conclusions: We believe the findings of this study will help evaluate the impact of the COVID-19 pandemic on the mental health conditions of health professionals in Brazil as well as contribute to the planning and implementation of appropriate measures that can alleviate these mental health challenges. International Registered Report Identifier (IRRID): DERR1-10.2196/2429

Rationale, study design, and analysis plan of the Alveolar Recruitment for ARDS Trial (ART): Study protocol for a randomized controlled trial

Background: Acute respiratory distress syndrome (ARDS) is associated with high in-hospital mortality. Alveolar recruitment followed by ventilation at optimal titrated PEEP may reduce ventilator-induced lung injury and improve oxygenation in patients with ARDS, but the effects on mortality and other clinical outcomes remain unknown. This article reports the rationale, study design, and analysis plan of the Alveolar Recruitment for ARDS Trial (ART). Methods/Design: ART is a pragmatic, multicenter, randomized (concealed), controlled trial, which aims to determine if maximum stepwise alveolar recruitment associated with PEEP titration is able to increase 28-day survival in patients with ARDS compared to conventional treatment (ARDSNet strategy). We will enroll adult patients with ARDS of less than 72 h duration. The intervention group will receive an alveolar recruitment maneuver, with stepwise increases of PEEP achieving 45 cmH(2)O and peak pressure of 60 cmH2O, followed by ventilation with optimal PEEP titrated according to the static compliance of the respiratory system. In the control group, mechanical ventilation will follow a conventional protocol (ARDSNet). In both groups, we will use controlled volume mode with low tidal volumes (4 to 6 mL/kg of predicted body weight) and targeting plateau pressure <= 30 cmH2O. The primary outcome is 28-day survival, and the secondary outcomes are: length of ICU stay; length of hospital stay; pneumothorax requiring chest tube during first 7 days; barotrauma during first 7 days; mechanical ventilation-free days from days 1 to 28; ICU, in-hospital, and 6-month survival. ART is an event-guided trial planned to last until 520 events (deaths within 28 days) are observed. These events allow detection of a hazard ratio of 0.75, with 90% power and two-tailed type I error of 5%. All analysis will follow the intention-to-treat principle. Discussion: If the ART strategy with maximum recruitment and PEEP titration improves 28-day survival, this will represent a notable advance to the care of ARDS patients. Conversely, if the ART strategy is similar or inferior to the current evidence-based strategy (ARDSNet), this should also change current practice as many institutions routinely employ recruitment maneuvers and set PEEP levels according to some titration method.Hospital do Coracao (HCor) as part of the Program 'Hospitais de Excelencia a Servico do SUS (PROADI-SUS)'Brazilian Ministry of Healt

Omecamtiv mecarbil in chronic heart failure with reduced ejection fraction, GALACTIC‐HF: baseline characteristics and comparison with contemporary clinical trials

Aims: The safety and efficacy of the novel selective cardiac myosin activator, omecamtiv mecarbil, in patients with heart failure with reduced ejection fraction (HFrEF) is tested in the Global Approach to Lowering Adverse Cardiac outcomes Through Improving Contractility in Heart Failure (GALACTIC‐HF) trial. Here we describe the baseline characteristics of participants in GALACTIC‐HF and how these compare with other contemporary trials. Methods and Results: Adults with established HFrEF, New York Heart Association functional class (NYHA) ≥ II, EF ≤35%, elevated natriuretic peptides and either current hospitalization for HF or history of hospitalization/ emergency department visit for HF within a year were randomized to either placebo or omecamtiv mecarbil (pharmacokinetic‐guided dosing: 25, 37.5 or 50 mg bid). 8256 patients [male (79%), non‐white (22%), mean age 65 years] were enrolled with a mean EF 27%, ischemic etiology in 54%, NYHA II 53% and III/IV 47%, and median NT‐proBNP 1971 pg/mL. HF therapies at baseline were among the most effectively employed in contemporary HF trials. GALACTIC‐HF randomized patients representative of recent HF registries and trials with substantial numbers of patients also having characteristics understudied in previous trials including more from North America (n = 1386), enrolled as inpatients (n = 2084), systolic blood pressure < 100 mmHg (n = 1127), estimated glomerular filtration rate < 30 mL/min/1.73 m2 (n = 528), and treated with sacubitril‐valsartan at baseline (n = 1594). Conclusions: GALACTIC‐HF enrolled a well‐treated, high‐risk population from both inpatient and outpatient settings, which will provide a definitive evaluation of the efficacy and safety of this novel therapy, as well as informing its potential future implementation

Experimental validation of a continuous-time MCSI algorithm with bounded adaptive gains

Model reference adaptive control algorithms with minimal controller synthesis have proven to be an effective solution to tame the behaviour of linear systems subject to unknown or time-varying parameters, unmodelled dynamics and disturbances. However, a major drawback of the technique is that the adaptive control gains might exhibit an unbounded behaviour when facing bounded disturbances. Recently, a minimal controller synthesis algorithm with an integral part and either parameter projection or σ-modification strategies was proposed to guarantee boundedness of the adaptive gains. In this article, these controllers are experimentally validated for the first time by using an electro-mechanical system subject to significant rapidly varying disturbances and parametric uncertainty. Experimental results confirm the effectiveness of the modified minimal controller synthesis methods to keep the adaptive control gains bounded while providing, at the same time, tracking performances similar to that of the original algorithm

Experimental validation of a continuous-time MCSI algorithm with bounded adaptive gains

Model reference adaptive control algorithms with minimal controller synthesis have proven to be an effective solution to tame the behaviour of linear systems subject to unknown or time-varying parameters, unmodelled dynamics and disturbances. However, a major drawback of the technique is that the adaptive control gains might exhibit an unbounded behaviour when facing bounded disturbances. Recently, a minimal controller synthesis algorithm with an integral part and either parameter projection or σ-modification strategies was proposed to guarantee boundedness of the adaptive gains. In this article, these controllers are experimentally validated for the first time by using an electro-mechanical system subject to significant rapidly varying disturbances and parametric uncertainty. Experimental results confirm the effectiveness of the modified minimal controller synthesis methods to keep the adaptive control gains bounded while providing, at the same time, tracking performances similar to that of the original algorithm

Revisión de control adaptativo por modelo de referencia con síntesis de controlador mínima y aplicación al control de velocidad de un motor DC

En este artículo se revisan los aspectos basicos del Control Adaptativo por Modelo de Referencia con Síntesis de Controlador Mínima, tanto en su version de tiempo continuo como en la de tiempo discreto. A su vez, se ilustran sus principales características de funcionamiento a partir del control de velocidad de un motor DC con parametros inciertos sometido a perturbaciones periódicas, para el cual se aportan resultados numericos y experimentale

State of the art on animal embryonic chimeras

Embryonic chimerism is generally used in basic research and in vivo diagnosis of undifferentiated embryonic stem cells (ESC), mostly using mice embryos, although there have been reports in the literature on using rat, rabbit, sheep, chicken, primate, bovine, goat and pig embryos. Several techniques can currently be used to produce chimeric embryos, including microinjection, co-culture with ESC, fusion and aggregation. Although microinjection is the most commonly used method in mice, the mere aggregation of embryos with ESC may result in viable chimeras and be as efficient as microinjection. In mice, this chimerism technique has been shown to have the advantage of aggregating embryos in different stages of development with different ploidy, in addition to using ESC in the tetraploid complementation assay. Compared to other techniques for producing chimeras, the aggregation technique is a cheaper, faster and easier methodology to be performed. Moreover, aggregation can be simplified by chemically removing the zona pellucida with pronase or acidic Tyrode’s solution and be enhanced by using the Well of the Well culture system in combination with adhesion molecules, such as phytohemagglutinin. The most commonly used stages for chimerism by aggregation are those that precede the full compaction of the morula. In these stages, embryos have low-tension adherent junctions at the tangential point between two blastomeres. During the embryonic development of mice, the inner cell mass differentiates into epiblast and hypoblast. These layers will originate the fetal tissues and a portion of the extraembryonic tissues (yolk sac, allantois and amnion), whereas the trophectoderm (TE) gives rise to the chorion. A functional TE is essential for the complex molecular communications that occur between the embryo and the uterus. Embryos produced by somatic cell nuclear transfer, such as commercial cattle clones or endangered species, are subject to large fetal and neonatal losses. Hence embryo complementation with heterologous TE could be of assistance to decrease these losses and might as well assist development of high-value embryos in other approaches