Control robusto de reactores continuos de tanque agitado para la producción de biohidrógeno

114 páginas. Maestría en Ingeniería de Procesos.Un tema relevante de hoy en día es el cambio climático, el cual se genera entre otras cosas por la gran cantidad de gases arrojados a la atmósfera, los cuales son precursores del efecto invernadero. Una fuente principal de estos gases de efecto invernadero son las emisiones de vehículos motorizados a través de la combustión de combustibles fósiles. Más aun, uno de los mayores desafíos de nuestro siglo es cubrir la demanda mundial de energía, debido al incremento de la población y al aumento del nivel de vida. Sumado a esto, las reservas de combustibles fósiles son cada vez menos accesibles a medida que se consumen las de fácil acceso, por lo que el precio de dicho combustible cada vez es más elevado. Con la finalidad de mitigar efectos ambientales y tener seguridad energética, se ha propuesto la producción del hidrógeno por medio de procesos biológicos. El hidrógeno es un combustible con alto contenido energético y durante su combustión solo se genera agua como producto resultante, lo que reduce en forma importante los efectos ambientales de los combustibles convencionales. El hidrógeno se puede producir mediante diferentes métodos. Uno de los más prometedores es por métodos biológicos, el cual emplea biomasa como materia prima. Con la producción del hidrógeno a partir de un sustrato se pueden obtener diversos beneficios, principalmente la obtención de energía limpia y la gestión de desechos. Sin embargo algunas desventajas de la producción de hidrógeno a partir de biomasa son los bajos niveles de producción de hidrógeno así como la tasa de degradación del sustrato. En consecuencia los procesos continuos son preferibles para el aumento en la producción a largo plazo. Se debe considerar que la operación convencional de procesos biotecnológicos continuos está sujeta a cambios importantes en la carga orgánica del sustrato, la actividad microbiana y las condiciones ambientales. Además, existe la necesidad de optimizar las condiciones para mejorar su productividad a largo plazo. Controlar un proceso biotecnológico puede ser un problema complicado debido a dificultades inherentes tales como la cinética no lineal y las incertidumbres del modelo. En este trabajo, se presentan dos métodos biológicos de producción de hidrógeno, la fermentación oscura y la fotofermentación, a los cuales se les implementa su optimización para la producción de hidrógeno en un CSTR. Además, para garantizar el proceso en las condiciones óptimas, se propone un enfoque de control robusto y práctico. Los resultados muestran que es posible mejorar la operación convencional y la producción de hidrógeno en reactores continuos

Mortality and pulmonary complications in patients undergoing surgery with perioperative SARS-CoV-2 infection: an international cohort study

Background: The impact of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on postoperative recovery needs to be understood to inform clinical decision making during and after the COVID-19 pandemic. This study reports 30-day mortality and pulmonary complication rates in patients with perioperative SARS-CoV-2 infection. Methods: This international, multicentre, cohort study at 235 hospitals in 24 countries included all patients undergoing surgery who had SARS-CoV-2 infection confirmed within 7 days before or 30 days after surgery. The primary outcome measure was 30-day postoperative mortality and was assessed in all enrolled patients. The main secondary outcome measure was pulmonary complications, defined as pneumonia, acute respiratory distress syndrome, or unexpected postoperative ventilation. Findings: This analysis includes 1128 patients who had surgery between Jan 1 and March 31, 2020, of whom 835 (74·0%) had emergency surgery and 280 (24·8%) had elective surgery. SARS-CoV-2 infection was confirmed preoperatively in 294 (26·1%) patients. 30-day mortality was 23·8% (268 of 1128). Pulmonary complications occurred in 577 (51·2%) of 1128 patients; 30-day mortality in these patients was 38·0% (219 of 577), accounting for 81·7% (219 of 268) of all deaths. In adjusted analyses, 30-day mortality was associated with male sex (odds ratio 1·75 [95% CI 1·28–2·40], p\textless0·0001), age 70 years or older versus younger than 70 years (2·30 [1·65–3·22], p\textless0·0001), American Society of Anesthesiologists grades 3–5 versus grades 1–2 (2·35 [1·57–3·53], p\textless0·0001), malignant versus benign or obstetric diagnosis (1·55 [1·01–2·39], p=0·046), emergency versus elective surgery (1·67 [1·06–2·63], p=0·026), and major versus minor surgery (1·52 [1·01–2·31], p=0·047). Interpretation: Postoperative pulmonary complications occur in half of patients with perioperative SARS-CoV-2 infection and are associated with high mortality. Thresholds for surgery during the COVID-19 pandemic should be higher than during normal practice, particularly in men aged 70 years and older. Consideration should be given for postponing non-urgent procedures and promoting non-operative treatment to delay or avoid the need for surgery. Funding: National Institute for Health Research (NIHR), Association of Coloproctology of Great Britain and Ireland, Bowel and Cancer Research, Bowel Disease Research Foundation, Association of Upper Gastrointestinal Surgeons, British Association of Surgical Oncology, British Gynaecological Cancer Society, European Society of Coloproctology, NIHR Academy, Sarcoma UK, Vascular Society for Great Britain and Ireland, and Yorkshire Cancer Research

Global urban environmental change drives adaptation in white clover

Urbanization transforms environments in ways that alter biological evolution. We examined whether urban environmental change drives parallel evolution by sampling 110,019 white clover plants from 6169 populations in 160 cities globally. Plants were assayed for a Mendelian antiherbivore defense that also affects tolerance to abiotic stressors. Urban-rural gradients were associated with the evolution of clines in defense in 47% of cities throughout the world. Variation in the strength of clines was explained by environmental changes in drought stress and vegetation cover that varied among cities. Sequencing 2074 genomes from 26 cities revealed that the evolution of urban-rural clines was best explained by adaptive evolution, but the degree of parallel adaptation varied among cities. Our results demonstrate that urbanization leads to adaptation at a global scale

The global retinoblastoma outcome study : a prospective, cluster-based analysis of 4064 patients from 149 countries

DATA SHARING : The study data will become available online once all analyses are complete.BACKGROUND : Retinoblastoma is the most common intraocular cancer worldwide. There is some evidence to suggest that major differences exist in treatment outcomes for children with retinoblastoma from different regions, but these differences have not been assessed on a global scale. We aimed to report 3-year outcomes for children with retinoblastoma globally and to investigate factors associated with survival. METHODS : We did a prospective cluster-based analysis of treatment-naive patients with retinoblastoma who were diagnosed between Jan 1, 2017, and Dec 31, 2017, then treated and followed up for 3 years. Patients were recruited from 260 specialised treatment centres worldwide. Data were obtained from participating centres on primary and additional treatments, duration of follow-up, metastasis, eye globe salvage, and survival outcome. We analysed time to death and time to enucleation with Cox regression models. FINDINGS : The cohort included 4064 children from 149 countries. The median age at diagnosis was 23·2 months (IQR 11·0–36·5). Extraocular tumour spread (cT4 of the cTNMH classification) at diagnosis was reported in five (0·8%) of 636 children from high-income countries, 55 (5·4%) of 1027 children from upper-middle-income countries, 342 (19·7%) of 1738 children from lower-middle-income countries, and 196 (42·9%) of 457 children from low-income countries. Enucleation surgery was available for all children and intravenous chemotherapy was available for 4014 (98·8%) of 4064 children. The 3-year survival rate was 99·5% (95% CI 98·8–100·0) for children from high-income countries, 91·2% (89·5–93·0) for children from upper-middle-income countries, 80·3% (78·3–82·3) for children from lower-middle-income countries, and 57·3% (52·1-63·0) for children from low-income countries. On analysis, independent factors for worse survival were residence in low-income countries compared to high-income countries (hazard ratio 16·67; 95% CI 4·76–50·00), cT4 advanced tumour compared to cT1 (8·98; 4·44–18·18), and older age at diagnosis in children up to 3 years (1·38 per year; 1·23–1·56). For children aged 3–7 years, the mortality risk decreased slightly (p=0·0104 for the change in slope). INTERPRETATION : This study, estimated to include approximately half of all new retinoblastoma cases worldwide in 2017, shows profound inequity in survival of children depending on the national income level of their country of residence. In high-income countries, death from retinoblastoma is rare, whereas in low-income countries estimated 3-year survival is just over 50%. Although essential treatments are available in nearly all countries, early diagnosis and treatment in low-income countries are key to improving survival outcomes.The Queen Elizabeth Diamond Jubilee Trust and the Wellcome Trust.https://www.thelancet.com/journals/langlo/homeam2023Paediatrics and Child Healt

Robust Master-Slave Synchronization of Neuronal Systems

The desire to understand physiological mechanisms of neuronal systems has led to the introduction of engineering concepts to explain how the brain works. The synchronization of neurons is a central topic in understanding the behavior of living organisms in neurosciences and has been addressed using concepts from control engineering. We introduce a simple and reliable robust synchronization approach for neuronal systems. The proposed synchronization method is based on a master-slave configuration in conjunction with a coupling input enhanced with compensation of model uncertainties. Our approach has two nice features for the synchronization of neuronal systems: (i) a simple structure that uses the minimum information and (ii) good robustness properties against model uncertainties and noise. Two benchmark neuronal systems, Hodgkin-Huxley and Hindmarsh-Rose neurons, are used to illustrate our findings. The proposed synchronization approach is aimed at gaining insight into the effect of external electrical stimulation of nerve cells

Income redistribution in Latin America: A microsimulation approach

We analyse the effect of taxes and benefits on income distribution of six Latin American countries: Argentina, Bolivia, Colombia, Ecuador, Uruguay, and Venezuela. Our analysis makes use of tax-benefit microsimulation models based on harmonized household representative survey data and developed within the structure of EUROMOD. The analysis focuses on the relative importance of tax-benefit instruments across countries and on the effect of taxes and benefits on poverty and inequality. The selected countries represent a wide range of cases in terms of the redistributive role of the tax-benefit system with Uruguay providing a large degree of redistribution, whereas the Bolivian system has a very modest role. We further exploit the advantages of our models and perform a simulation exercise whereby the most progressive income tax system of our set of countries is applied to the rest and assess its effect on inequality and revenue. Our paper represents the first study making use of microsimulation techniques to assess the redistributive role of tax-benefit systems in the region in a comparable manner, and highlights the advantages offered by microsimulation models to evaluate the effect of policy reforms aiming to improve social protection in the region