Abstract: Phosphorus (P) is a limiting element in the dynamics of legume-grass succession, because it fulfills different roles that imply functionality in the absorption efficiency with other elements such as Nitrogen and Iron (Fe), the latter especially in tropical soils. Rice has shaped the diet, economy, and culture of millions of people around the world. It is considered the third most produced crop after corn and wheat on the planet. China is the largest producer and consumer of rice in the world with an area of 30 million hectares with a total amount of 145 million tons, while Italy is the main producer of rice in Europe. with an area of 234,133 ha there is a rice production of more than million tons. Rice production faces agronomic and environmental challenges, such as the reduction of nutrient losses that can cause contamination of ecosystems, the increase of efficiency in fertilizer applications using alternative sources such as struvite, the use of friendly practices with the sustainable development of cover crops during the fallow period to improve soil fertility. Therefore, this thesis aimed to evaluate the role of P on biological N fixation (BNF) efficiency in legumes and the role of these cover crops on nutrient dynamics in temperate rice agrosystems (Northern Italy). Another objective of this thesis was developed under tropical conditions and aimed to evaluate P forms in acid soils under different water management and fertilized with conventional and alternative phosphate fertilizers. Resumen: El fósforo (P) es un macronutriente limitante en la dinámica de la mayoría de cultivos y particularmente cumple un papel importante en la sucesión de leguminosa-gramínea, debido a que cumple diferentes roles que implican funcionalidad en la eficiencia en la absorción con otros elementos como el Nitrógeno y el Hierro (Fe), sobre todo este último en suelos tropicales. El arroz ha dado forma a la dieta, la economía y la cultura de millones de personas en todo el mundo. Se considera el tercer cultivo más producido después del maíz y el trigo en el planeta. China es el mayor productor y consumidor de arroz del mundo con una superficie de 30 millones de hectáreas con una cantidad total de 145 millones de toneladas. Italia es el principal productor de arroz de Europa con una superficie de 234.133 hay una producción de arroz superior a 1.5 millones de toneladas. La producción de arroz enfrenta problemas a nivel agronómico y ambiental, como el de disminuir las pérdidas de nutrientes que pueden ocasionar contaminaciones en suelos y aguas, eficiencia en las aplicaciones de fertilizantes empleando fuentes alternativas como la estruvita, el uso de prácticas amigables con el desarrollo sostenible de los arrozales como la sucesión y rotación de la relación leguminosa-gramínea que altera la fertilidad de los suelos. De la tesis doctoral se han publicado 3 artículos: 1) Phosphorus Dynamics in the Soil–Plant–Environment Relationship in Cropping Systems: A Review (Journal Applied Sciences). 2)Cover Crops Increase N and P Cycling and Rice Productivity in Temperate Cropping Systems (Journal Agronomy) 3) Can Organic P Inputs Alleviate P Limitation Effects on Nutrient Uptake and Biological N2-Fixing Capacity of Hairy Vetch (Vicia villosa)? (Journal Soil Science and Plant Nutrition).

Abstract: The alternative of combining bioenergy with carbon capture and storage (BECCS) offers the prospect of minimizing greenhouse gas (GHG) emissions or even removing CO2 from the atmosphere. BECCS are an important approach to reach the target of 2°C as the maximum increase in the global average temperature by the end of this century. In Brazil, attention is drawn to the opportunities for BECCS in the sugar-energy sector, in which it is possible to combine the production of fuels and the generation of electricity from renewable biomass, and integrate them to capture the CO2 emitted in the conversion. This work aims to evaluate the technical-economic performance of BECCS systems in the generation of electricity using residual sugarcane biomass, in the Brazilian context. The integration of the carbon capture process in a typical sugarcane plant was evaluated considering two different cogeneration technologies and, finally, a thermoelectric plant was considered in which this unit uses surplus biomass from a nearby industry. The use of residual sugarcane biomass (bagasse and straw) was considered because of its availability on a large scale and at a relatively low cost in Brazilian sugarcane mills. The two power technologies included, the conventional condensing-extraction steam turbine (CEST), and biomass integrated gasification to combined cycles (BIG-CC). For the capture process, pre and post-combustion routes were compared, both technically feasible but impacted by high demands of steam. Compared to cogeneration, the results for thermoelectric power are favorable, but its location needs to be in a region where there is potentially a large amount of surplus biomass. The current stage of technological development of the BIG-CC technology indicates the impossibility of generating electricity and capturing CO2 in the short to medium term, a horizon in which the CEST technology can be used in demonstration projects. However, the alternative of capturing CO2 from fermentation, in the production of ethanol, should be prioritized, as it implies few energy penalties in the industry, has a relatively low cost and can reduce the carbon footprint of the biofuel.

Abstract: This project follows the complete development process of a sustainable building which intend to optimize the natural and built conditions, to merge the architecture with the sustainability; applied to the renovation of the BUILDING H in Palogrande Campus, Universidad Nacional de Colombia in the city of Manizales. Along this work the author put in practice the different methods of analysis and problem solution learned in the Politecnico di Milano, which are oriented to create a user experience focused in the current necessity of saving energy, having at simple sight the building spaces, systems, elements and components which will work to carry out this purpose, being the building use an interactive process between the users and the sustainability. A holistic approach leads the present project, starting from a general analysis of the physical, environmental, historical and social context at country, city, university and campus scale; the urban analysis considers the campus and its surrounding area, yet the design has been limited to the campus area; the architectural design follows the physical and social necessities and is connected with the sustainable strategies which intend to create an comfort environment with a low energy consumption; the details of the systems, elements and components are presented, as well as the structure analysis. Photographs, plans, schemes and renders illustrate the process and result. All the solutions proposed are ecofriendly oriented and expect to be a reference for future studies and design projects in another cities and functions.

Abstract: This study conducts an overview of false cognates between Spanish and Portuguese to propose the didactic strategy of associative mnemonics: associative images with associative sentences, this with the aim of reducing interference and improving the accuracy at the time of recalling false cognates. The study was designed with 30 Spanish-native Colombian speakers who learn Portuguese as a foreign language at the University. The findings show that the associative mnemonics improve participants performance just when associative images are included (experimental group) rather than just associative sentences (control group), there was a rising of 25,8% when comparing groups with and without associative images. Participants also demonstrated different perceptions of the cognates depending on the type of task that they face. Linking individual translations between both languages showed a performance of 85%, but when the task was about a written description of pictures, the performance lowered to 54%. This study gives light to the need of teachers and students to find diverse metacognitive techniques to differentiate complex lexicon in both languages. Resumen: Este estudio realiza un recorrido por los falsos cognados entre español y portugués para proponer la estrategia didáctica de la mnemotécnica asociativa: imágenes asociativas con frases asociativas, esto con el objetivo de reducir la interferencia y mejorar la precisión al momento de recordar falsos cognados. El estudio fue diseñado con 30 hispanohablantes colombianos que aprenden portugués como lengua extranjera en la Universidad. Los hallazgos muestran que los mnemotécnicos asociativos mejoran el rendimiento de los participantes solo cuando se incluyen imágenes asociativas (grupo experimental) en lugar de solo frases asociativas (grupo control), hubo un incremento del 25,8% al comparar grupos con y sin imágenes asociativas. Los participantes también demostraron diferentes percepciones de los cognados según el tipo de tarea que desempeñan. Las traducciones individuales entre ambos idiomas mostraron un rendimiento del 85 %, pero cuando la tarea se trataba de una descripción escrita de imágenes, el rendimiento bajó al 54 %. Este estudio revela la necesidad de docentes y estudiantes de encontrar diversas técnicas metacognitivas para diferenciar léxicos complejos en ambas lenguas.

Abstract: Information regarding the state of bridges is fundamental for maintaining a satisfactory performance level, given that deterioration may lead to bridge failure and thus, increased costs. Bridges face harsh environmental conditions and natural disasters are often inevitable and can be one of the main reasons for bridge collapse. Consequences from flooding events (e.g., scour) are responsible for a large percentage of failures in bridge structures. Therefore, the assessment of bridges susceptible to these phenomena is of utmost importance to identify possible mitigation needs. The objective of the present research is to present a consistent framework to obtain fragility curves associated with the inplane behavior of masonry arch bridges (MAB) under flood hazard. By implementing metamodeling techniques to the probabilistic analysis, a computational cost-efficient framework is proposed which is employed on a MAB “Ponte da Vala do Carregado” located in Portugal. A two-dimensional numerical model was constructed where the random variables that affect the structural capacity and the scouring process were considered. Finally, a parametric analysis, based on the geometric variations of the bridge structure and geotechnical variations of the foundation material (bed material), was implemented. The fragility curves show that failure probability increases when flow discharge increases, especially when the skew flow was considered. This will allow assessing the performance of bridges that may affect the network efficiency at important sections of the roadway system if damaged by a flood event. Resumen: La información sobre el estado de los puentes es fundamental para mantener un nivel de desempeño satisfactorio, dado que el deterioro puede conducir a la falla del puente y, por ende, a un aumento de los costos. Los puentes enfrentan duras condiciones ambientales y los desastres naturales a menudo son inevitables y pueden ser una de las principales razones del colapso del puente. Las consecuencias de las inundaciones (por ejemplo, la socavación) son responsables de un gran porcentaje de fallas en las estructuras de los puentes. Por lo tanto, la evaluación de puentes susceptibles a estos fenómenos es de suma importancia para identificar posibles necesidades de mitigación. El objetivo de la presente investigación es presentar un marco consistente para obtener curvas de fragilidad asociadas con el comportamiento en el plano de puentes de arco de mampostería (MAB) bajo peligro de inundación. Mediante la implementación de técnicas de metamodelado para el análisis probabilístico, se propone un marco computacional rentable que se emplea en un MAB ""Ponte da Vala do Carregado"" ubicado en Portugal. Se construyó un modelo numérico bidimensional donde se consideraron las variables aleatorias que afectan la capacidad estructural y el proceso de socavación. Finalmente, se implementó un análisis paramétrico, basado en las variaciones geométricas de la estructura del puente y las variaciones geotécnicas del material de cimentación (material del lecho). Las curvas de fragilidad muestran que la probabilidad de falla aumenta cuando aumenta la descarga del flujo, especialmente cuando se considera el flujo sesgado. Esto permitirá evaluar el desempeño de los puentes que pueden afectar la eficiencia de la red en secciones importantes del sistema vial si se dañan por una inundación.

Abstract: The 2016 peace accords between the Colombian state and the FARC created great expectations of peace across the region. However, four years later, Colombia is experiencing a growing wave of violence from numerous actors, including former FARC dissidents. What drove the emergence of splinter groups after the 2016 peace accords? This thesis argues that insurgents’ levels of cohesiveness and ideological commitment during negotiations significantly condition the long-term prospects for successful accord implementation. When insurgencies enter these processes with low levels of these two factors, peace accords tend to transform, rather than end, the conflict. The thesis examines this argument through an analysis of the FARC’s organizational and ideological properties throughout history and finds that while the FARC had traditionally been a cohesive organization, during the 2000s the COIN strategy and Plan Colombia weakened its organizational structure. Furthermore, its incorporation in the drug trade contributed to the dilution of its ideological commitment. When accords were signed, the FARC lacked the necessary levels of cohesiveness and commitment to implement and enforce the accords in their ranks, causing the emergence of splinter groups. This thesis recommends that in an eventual negotiation with insurgencies, governments must give careful consideration to both the organizational and ideological properties of such organizations to avoid splintering and recurrence of violence.

Abstract: Microfluidics is a relatively recent technology which involves the manipulation of fluids geometrically constrained to small scales. These devices have been gaining attention, especially due to the broad range of potential applications, being one of them microreactors. In this project, the optimum flow conditions for generation droplets under merging regime were established, identifying most important variables, which influence the regime desired in this type of application. Capillary and Reynolds numbers were found as the parameters which determine the region in which the system is performed. These numbers are subject to the interfacial tension, viscosity, and flowrate which are the most sensitive variables that modify all the regimes. Likewise, it was identified that the geometry of the microdevice influences on the system. Therefore, several microdevices were designed with different geometries where the viscosity, the flowrate, and the width ratio were varied at fixed interfacial tension, to assess their impact. It was found that by increasing the viscosity and flowrate, the shear forces inside the microdevices increase proportionally, giving way to undesired laminar regimes and bigger droplets. The width ratio has an indirect impact on the regime obtained, by increasing the amount of water entering the main channel. Phase diagrams illustrate the optimal conditions for merging regime, where the most optimal values found to have this regime and smallest droplet were by using width ratio of 1, and flowrates of 3.5ml/h and 0.8ml/h in the continuous phase and dispersed phases, respectively, using silicone oil of 5cSt. The results found in this study can contribute to the development of further research, including the formation of nanoparticles to carry out chemical reactions in a micro scale. Resumen: La microfluídica es una tecnología relativamente reciente que implica la manipulación de fluidos restringidos geométricamente a pequeñas escalas. Estos dispositivos han ido ganando atención, especialmente debido a la amplia gama de aplicaciones potenciales, siendo una de ellas los microrreactores. En este proyecto se establecieron las condiciones óptimas de flujo para la generación de gotas en régimen de fusión, identificando las variables más importantes, que influyen en el régimen deseado en este tipo de aplicación. Los números de capilaridad y de Reynolds se encontraron como los parámetros que determinan la región en la que se desarrolla el sistema. Estos números están sujetos a la tensión interfacial, la viscosidad y el caudal, que son las variables más sensibles que modifican todos los regímenes. Asimismo, se identificó que la geometría del microdispositivo influye en el sistema. Por lo tanto, se diseñaron varios microdispositivos con diferentes geometrías en los que la viscosidad, la velocidad de flujo y la relación de anchura se variaron a una tensión interfacial fija, para evaluar su impacto. Se comprobó que al aumentar la viscosidad y la velocidad de flujo, las fuerzas de cizallamiento en el interior de los microdispositivos aumentan proporcionalmente, dando lugar a regímenes laminares no deseados y a gotas más grandes. La relación de anchura tiene un impacto indirecto en el régimen obtenido, al aumentar la cantidad de agua que entra en el canal principal. Los diagramas de fase ilustran las condiciones óptimas para el régimen de fusión, donde los valores más óptimos encontrados para tener este régimen y la gota más pequeña fueron utilizandos a una la relación de anchura de 1, y caudales de 3,5ml/h y 0,8ml/h en la fase continua y en la fase dispersa, respectivamente, utilizando aceite de silicona de 5cSt. Los resultados encontrados en este estudio pueden contribuir al desarrollo de nuevas investigaciones, incluyendo la formación de nanopartículas para llevar a cabo reacciones químicas a microescala.

Abstract: This paper describes the treatment of lexis in three Spanish as a foreign language (SFL) textbooks recently produced in Colombia. To achieve this aim, the typology of lexical activities proposed in three units of each textbook has been analysed according to the most current theories on vocabulary teaching and by means of grids designed for this purpose. The evolution of the treatment of vocabulary in textbooks produced at different times was also analysed. Among the most notable conclusions, it has been found that the teaching strategies most commonly used in the textbooks are based on the task-based approach and the key to the evolution of the material produced in Colombia has been the design of activities prioritising the students and their needs. Indeed, the most recent textbooks have changed pedagogical and presentational aspects and can be said to apply current SFL teaching guidelines, such as the use of audiovisual material as a basis for the development of the textbook. The relevance of this study is reflected in the need to improve the quality of textbooks in Colombia and their promotion. Resumen: En este trabajo se realiza una descripción del tratamiento del léxico en tres manuales de español como lengua extranjera (ELE) recientemente producidos en Colombia. Para llegar a este fin, se ha analizado la tipología de actividades de léxico propuestas en tres unidades de cada manual conforme a las teorías más actuales acerca de la enseñanza de vocabulario y por medio de unas parrillas diseñadas para tal fin. Asimismo, se ha analizado la evolución del tratamiento de vocabulario en manuales producidos en distintos momentos. Entre las conclusiones destacables, se ha encontrado que las estrategias de enseñanza más utilizadas en los manuales se apoyan en el enfoque basado en tareas y la clave para la evolución del material producido en Colombia ha sido el diseño de actividades priorizando al alumnado y sus necesidades. Efectivamente los manuales más recientes han cambiado aspectos pedagógicos y de presentación y se podría decir que aplican las directrices actuales de enseñanza de ELE, como la utilización de material audiovisual como base para el desarrollo del manual. La pertinencia de este estudio se ve reflejada en la necesidad de mejorar la calidad de los manuales en Colombia y su difusión.

Abstract: Colombian schools' mental health approaches to secondary students have not been researched deeply in the country. Therefore, there is a need to understand how schools are currently promoting students' mental health to identify strengths and obstacles to improving the provision of mental health approaches in Colombian schools. The present study explored Colombian secondary school teachers' perceptions of schools' approaches toward students' mental health. Seven semi-structured in-depth interviews with teachers from different Colombian secondary schools, mainly from Bogotá, were carried out. Thematic analysis was used to analyse the data. The study found that schools have different strategies to promote students' mental health, including mental health-related classes in the curriculum, activities done by the psychology department, the Parent Training Programme, extracurricular activities and targeting common adolescent issues. However, there are various obstacles that schools need to address to improve mental health promotion. Barriers include the lack of correct implementation of combing mental health skills within the subjects, lack of continuity of mental health activities, lack of reflection and significant learning in the strategies, not talking directly about mental health, and engaging better parents and school staff in students' mental health promotion. Moreover, the study considers practical implications for Colombian schools and the Colombian government to improve mental health approaches in schools and contribute to better mental health in Colombian adolescents. Finally, future studies are discussed to contribute to deep research on Colombian secondary students' mental health. Resumen: Los enfoques en salud mental de los colegios de Colombia para los estudiantes de bachillerato no han sido investigados profundamente en el país. Por lo tanto, existe la necesidad de entender cómo los colegios están actualmente promoviendo la salud mental de los estudiantes para identificar fortalezas y obstáculos y así mejorar la provisión de los enfoques de salud mental en los colegios de Colombia. El presente estudio exploró las percepciones de los profesores de bachillerato sobre los enfoques de los colegios hacia la salud mental de los estudiantes. Se realizaron siete entrevistas semiestructuradas a docentes de diferentes colegios de Colombia, principalmente de Bogotá, y se utilizó el análisis temático para analizar los datos. El estudio encontró que los colegios tienen diferentes estrategias para promover la salud mental de los estudiantes, incluyendo clases relacionadas con la salud mental en el plan de estudios, actividades realizadas por el departamento de psicología, la escuela de padres, actividades extracurriculares y abordaje de problemáticas comunes de la adolescencia. Sin embargo, se encontraron varios obstáculos que los colegios deben abordar para mejorar la promoción de salud mental. Los obstáculos incluyen la falta de implementación correcta de habilidades de salud mental dentro de las asignaturas, falta de continuidad de las actividades de salud mental, falta de reflexión y aprendizaje significativo en las actividades, no hablar directamente sobre la salud mental, y falta de fomentación en la participación de padres y colaboradores del colegio en la promoción de salud mental de los estudiantes. Además, el estudio considera implicaciones prácticas para los colegios de Colombia y el gobierno colombiano para mejorar los enfoques de salud mental en los colegios y contribuir a una mejor salud mental en los adolescentes colombianos. Finalmente, se discuten futuros estudios que contribuyan a una investigación profunda sobre la educación secundaria colombiana.

Abstract: The continuous development and upgrading of computational methods has allowed for great advances in scientific research in fields like astrophysics. The capacity of this methods to accurately reproduce processes and environments that can not be directly observed makes them specially useful in areas like planet formation, as the stages of planetary growth can be rarely observed and directly studied. From dust to planetesimals, protoplanetary embryos and terrestrial planets, planetary growth is still a field of open research, specially as many processes like the formation of planetesimals and the origin of water in terrestrial planets remains unclear. Specially for the origin of water a number of hypothesis have been postulated including both endogenous and exogenous sources, such that the most plausible source of the water accreted by the inner planets of the Solar System corresponds to bodies originated in the outer asteroid belt. The delivery of water is most likely carried out by massive and decisive collisions of similar sized bodies during the late-stage accretion phase of planetary growth. In this master thesis, the focus is placed on studying in detail this type of collisions, utilizing a post-collisional processing python code using the N-body integrator REBOUND, which determines a wide array of parameters for the resulting fragments, as final mass and number of collisions, while at the same time performing a gravitational analysis of the system in order to obtain gravitationally bound aggregates, their orbits and their respective orbital parameters. For a scenario consisting of four collisional events, initially performed by Burger et al. (2020), we obtain unique gravitational systems as a direct consequence of the different impact parameters presented by each collision of the scenario, where the impact angle has the greatest incidence on the outcome of the collision, such that scenarios with large grazing angles result in systems that are completely gravitationally bound, while scenarios with smaller straight-on angles result in systems with numerous fragments in independent trajectories. Additionally, from the analysis of the post-collisional system we obtain a protoplanetary embryo with a growth path consistent with a viable candidate for a terrestrial planet in the Solar System, presenting a final stable co-planar circular orbit located in the habitable zone.