Abstract: The concept of semi-regular sequences was introduced in order to assess the complexity of Gröumlbner basis algorithms such as F4 for the solution of polynomial equations. Despite the experimental evidence that semi-regular sequences are common, it was unknown whether there existed semi-regular sequences for all n, except in extremely trivial situations. In the present work, I prove some results on the existence and non-existence of semi-regular sequences. It was observed by J. Schlather and T. Hodges that if an element of degree d in Β(n)-variables is semi-regular, then we must have n≤3d. In this thesis, I establish precisely when the elementary symmetric polynomial of degree d is semi-regular. In particular, when d=2t and n=3d, the elementary symmetric polynomial of degree d is semi-regular establishing that the bound given by J. Schlather and T. Hodges is sharp for infinitely many n. For the general case of existence of semi-regular sequences Bardet, Faug&egravere and Salvy conjecture that the proportion π(n, m, d1, . . . , dm) of semiregular sequences over F2 in the set Ε(n, m, d1, . . . , dm) of algebraic systems of mequations of degrees d1, . . . , dm in n-variables tends to 1 as n tends to infinity. In this work, I show that for a fixed choice of (m, d1, . . . , dm), we have that limn→∞ π(n, m, d1, .. . , dm ) — 0 showing that the conjecture is false in this case.

Abstract: The present dissertation consists of three main chapters of self-contained works about international human migration and migrant's integration in the host society. The empirical studies can be read independently since each chapter addresses a research question and contains a specific literature review, methodology, empirical results, conclusions, and discussion of the results. As a summary: first, it estimates the joint effects of the preexisting stocks of migrant and ancestral distance to predict migration inflows. Second, it studies the children of migrants in the United States of America, their performance in high school when compared to the children of natives, and the role of educational aspirations and expectations as determinant factors behind their educational performance. Third, it examines international students and the role of financial aid on the successful completion of higher education abroad using data from Colfuturo's scholarship loan program. Resumen: La presente tesis consta de tres capítulos principales dedicados a estudiar la migración humana internacional y la integración de los migrantes en la sociedad de acogida. Los estudios empíricos se pueden leer de forma independiente ya que cada capítulo aborda una pregunta de investigación, contiene una revisión de literatura específica, metodología, resultados empíricos, conclusiones y discusión de los resultados. Como resumen: primero, esta tesis estima los efectos conjuntos de los stocks preexistentes de distancia migrante y ancestral para predecir los flujos migratorios. En segundo lugar, estudia a los hijos de migrantes en los Estados Unidos de América, su desempeño en la escuela secundaria en comparación con los hijos de nativos, y el papel de las aspiraciones y expectativas educativas como factores determinantes de su desempeño educativo. En tercer lugar, examina a los estudiantes internacionales y el papel de la ayuda financiera en la finalización exitosa de la educación superior en el extranjero utilizando datos del programa de becas / préstamos de Colfuturo.

Resumen: El estudio de las maternidades no heteronormativas viene ampliando el concepto de familia hacia una comprensión que se acerca cada vez más a los aspectos sociales del parentesco y la crianza. El objetivo de este trabajo es mostrar los patrones y las discontinuidades que aparecen en las narrativas de un grupo de mujeres lesbianas, bisexuales, -o que se salen de la heteronorma- en la configuración de sus proyectos de maternidad. Parto del análisis de sus narrativas para señalar que la reproducción asistida es un lugar de disputa, pues: i) apuesta por una construcción colectiva del parentesco por medio del diálogo y las conversaciones, ii) se presenta como un desafío al modelo de parentesco basado en lazos genéticos, iii) abre caminos para formas creativas de familia, maternidad y crianza más allá de los determinismos y mandatos sexo-genéricos, iv) fomenta prácticas de resistencia y agencia contra la discriminación y violencia del heteropatriarcado, y al mismo tiempo v) es un campo atravesado por cuestiones de clase y raza que demarca categorías de mujeres por las formas en las que acceden y se relacionan con la maternidad en el contexto catalán.

Abstract: The world is facing a global refugee crisis where people are being forced to flee their countries mostly due to violence and poverty; crossing borders to new nations hoping to find not only a new life and stability but also peace without losing their identity. In Venezuela, the Refugee crisis was established as a crisis, until 2019, that is why in the same report, the country does not appear in the ranking of countries with the most international displacement. Venezuela would be the country with the second most international forced displacement, where more than 4 million Venezuelans have fled around the world in the past 5 years. 1.3 million of these refugees have been received by Colombia’s government in the past two. Colombia - both its government and its people - has been very open to receiving Venezuelan refugees and it has been able to find ways to provide them the best options and conditions for them to either stay in a temporary or in a permanent way, but the situation is challenging. But the rapidly increasing flows of immigrants crossing the border, the unexpected numbers of groups of people arriving in Colombia, and the problems Colombia on its own is facing (high unemployment and poverty rates to name a few) are fundamental for this crisis to be even more difficult to solve. It was difficult to find solutions in Colombia even before Venezuela’s crisis, today a state of emergency has been declared in most cities across the 2,300 kilometers of shared borders. Inspired and influenced by this crisis, this Capstone project aims to create a local solution to Venezuela’s refugee crisis in Colombia; one, that can be replicated in all places that are going through the same or similar circumstances. What development tools can be used or included in these specific communities as part of the solution? How can we transform this crisis into an opportunity for both Colombian communities and Venezuelan refugees? This study is focused on implementing circular economies recommendations in temporal shelters for Venezuelan refugees in Colombia. Specifically, shelters that are supervised by Carminates Tricolor a Colombian/Venezuelan nonprofit. Taking into account that there are various routes and multiple organizations involved, the project will start by creating recommendations to the temporal and local shelters located in the section between Cucuta and Bucaramanga, one of the most dangerous routes that the walkers cross to get to their final destinations.

Abstract: In 2017 the National Power Company in Iceland, Landsvirkjun, started the operation of a geothermal power plant in Theistareykir (Northeastern Iceland). The plant’s operation requires extraction, circulation, and injection of the geothermal fluids to produce energy. These processes depend on the existing fracture network of the reservoir. Therefore, geothermal energy exploitation requires knowledge of underground structures to identify potential fluid flow pathways. These are, in many cases, evidenced by the local seismicity. In this context, the GFZ German Research Center for Geosciences and Landsvirkjun chose this site for deploying a dense network of fifteen seismic broadband stations to monitor and characterize the field’s seismicity. The data coming from this very dense network allows us to implement and test an optimized processing scheme to perform a detailed analysis of the local seismicity. This study’s primary goal is to implement an efficient and reliable scheme to characterize the local seismicity of the Theistareykir geothermal field using the collected high-resolution seismic data from the dense network. I used several traditional earthquake seismology methods to detect, analyze, classify, and localize, repeating microseismic events. I first used a recursive STA/LTA algorithm to detect the local seismicity between January 1, 2018, until June 30, 2018. Using the detections, I manually reviewed and picked P- and Sphase arrival times. After an initial non-linear localization, I performed a correlation clustering analysis and identified two events with a high degree of waveform similarity. I corrected the picked phase arrivals using the cross-correlation coefficients of the events to a master trace. These events were relocated to improve their relative locations. Events of both clusters will be used in future studies for template-matching to detect and pick additional events within this period. The methodology applied here is meant as a guide to process upcoming seismic data of the geothermal field and efficiently perform a full seismological characterization using more massive datasets.

Resumen: A lo largo de este documento, se encontrarán la descripción de un contexto pedagógico a partir del cual se llegan a diferentes reflexiones, análisis didácticos, humanos y lingüísticos entre Colombia, Francia y Rusia. La creación y análisis de un manual que implementa el arte como medio y estrategia didáctica para la enseñanza-aprendizaje del francés como lengua extranjera y para la valorización de nuestra propia identidad individual e intercultural. En primer lugar, encontrarán la descripción de la situación de enseñanza en la cual la presente propuesta fue implementada. Enseguida, se presentarán las características de un sistema educativo que tiene algunas especificaciones primordiales por señalar. Allí conoceremos el contexto educativo y la organización diferenciada de una concepción académica al interior de la ciudad de Tunja en el departamento de Boyacá, Colombia. Por otro lado, se hará la presentación y argumentación del enfoque pedagógico abordado frente a la planeación de las clases y el desarrollo de esta propuesta pedagógica . Del mismo modo, se expondrán las selecciones didácticas en lo que concierne a la concepción y elaboración del presente manual, llamado Fl'évolución. Así pues, podremos analizar algunas sesiones de clase experimentadas y exponer el proyecto de mensajería "Rusia- Colombia" que fue implementado con estudiante de francés de los países mencionados anteriormente. Para finalizar, se darán a conocer las conclusiones de esta estadía lingüística correspondiente a la maestría del programa de lingüística, especialidad didáctica y del francés como lengua extranjera y segunda ofrecida por la Universidad de Poitiers en Francia. Résumé: Tout au long de ce document, vous allez trouver une description d’un contexte pédagogique à partir duquel il a été possible d’arriver à plusieurs réflexions et analyses didactiques et linguistiques. Premièrement, vous allez trouver la description de la situation d’enseignement. Elle va vous permettre de vous contextualiser face aux situations qui seront exposées juste après. Ensuite, je présenterai les caractéristiques d’un système éducatif qui a certains traits didactiques importants à souligner. Cette présentation sera l’occasion de connaitre le contexte éducatif et l’organisation différenciée d’une conception académique à l’intérieur de la ville de Tunja, Colombia. Puis, je ferai la présentation et l’argumentation de l’approche pédagogique adoptée face à la préparation des cours et le déroulement d’une pédagogie différenciée. Cela nous permettra de connaitre touts les facteurs sous-jacentsdidactiquement parlant. Ensuite je vais vous présenter mes choix didactiques en ce qui concerne la conception et l’élaboration du manuel FL’évolution. Ce qui me permettra d’analyser quelques-unes des séances expérimentées et de vous exposer le projet de messagerie « Russie- Colombie » qui a été implémenté pour des apprenants de français des pays préalablement mentionnés. Pour finir, j’exposerai les conclusions de ce stage correspondant au master 2 du programme de didactique de langues et français langue étrangère et seconde, offert par l’université de Poitiers en France. Finalement vous trouverez la bibliographie et les annexes qui servent d’illustration et de support au document suivant.

Abstract: This study presents the effect of dividend announcements on the share price of French companies from the luxury goods industry. The relevant theories used to explain this research were the “dividend irrelevance theorem” proposed by Miller and Modigliani (1961), where dividends do not have an impact in the share price; and the “dividend signaling hypothesis”, where the dividend policy affects the share price. The “dividend signaling hypothesis” was studied by Lintner (1956), Miller and Rock (1985), Grullon et al. (2002), Grullon et al. (2005), Flint et al. (2010), and Vazakidis and Athianos (2010). The application of this theories to the luxury industry was evaluated with statistical elements including the method of “event study”. Data was collected from Bloomberg, financial reports and reports of the general meeting of shareholders. The methodology proposed includes the quantitative analysis of the daily last price of the selected companies, their logarithmic returns as well as their abnormal returns, to demonstrate if they were statistically significant to accept or to reject the findings of Modigliani and Miller. All calculations and estimations were done by using Microsoft Excel®. The main conclusion of this study is that the theory of Miller and Modigliani is not applicable on the listed French luxury goods companies. And in terms of recommendations about the performance of the selected shares: the announcement of dividends has a negative impact between 3 or 4 days before the announcement, and a positive impact no later than 2 days after the announcement.

Abstract: The aim of this investigation is to assess the behavior of the low-cost sensors under different levels of temperature and relative humidity, which are the main parameters affecting their performance. Several set of experiments were carried out in both, laboratory and field conditions using four low-cost sensors from the company Alphasense. As a short summary of the experimental plan, the low-cost sensors were firstly tested under six relative humidity and four temperature levels against traditional reference instruments. This with the aim of developing a correction algorithm for these two parameters. Then the implementation of a low-cost dryer was evaluated which would reduce the influence of the mentioned parameters on the low-cost sensor behavior. All of these stated tests were performed in controlled conditions in the laboratory. In the end, a long-term experiment in the field was done. This experiment had a duration of one month, and its aim was to appraise the algorithm calculated from the laboratory when comparing their results against the concentrations measured by a monitoring station in Marienplatz, Stuttgart. The relative humidity levels achieved during the laboratory experiments were from 10% until 85%, increasing in steps of 15%, and the temperature levels were 10°C, 25°C, 35°C and 45°C. All low-cost sensors showed a significant improvement when the developed correction algorithm was applied, which is reflected in the selected evaluation parameters (MAPE, MAE, linearity and offset). The relative humidity levels used for the assessment of the low-cost dryer were 40%, 55%, 70% and 85%, finding similar results obtained from the previous experiments. However, with the advantage that in this case, after the drying process, the relative humidity and temperature levels were stable, which leads to avoid applying a complex correction algorithm. The concentrations measured by the low-cost sensors with the applied correction showed improved results, with absolute errors of 38.18 ppb, 7.64 ppb and 4.27 ppb for CO, NO and NO2, respectively. Further investigation is also suggested, regarding the use of different set of sensor for checking the reproducibility as well as dynamic changes in the influencing parameters.

Abstract: The present thesis’ objective is mapping opportunities for service design in Creative industries in Colombia that work by bridging academia and the professional practice, to provide conditions that help generate a healthier job market and business creation for the new and future professionals. The study considers the policies and statistics of the creative industries for finding opportunities and deepens in understanding needs and motivations of freelancers in design, filmmaking, and independent artists. As the latter depend on a different ecosystem, the results were focused on proposing a service system for designers and filmmakers. The research started with a literature review for a conceptual understanding of the Creative Industries in an international and historical context, and then focused on the Creative Industries sectors classification, statistics and characteristics in Colombia. The analysis continued with exploring international and national case studies focused on university-based entrepreneurship programs. Moreover, the field exploration used a Human centered design approach, gathering quantitative and qualitative data from students, graduates and freelancers in Bogota, Cali and Popayan through surveys and interviews, involving stakeholders in ideation processes and service prototyping. The analysis shows that stakeholders need capability building in entrepreneurship, increasing their knowledge of copyright and diversifying the activities along the value chain. A stronger link with academia would help to boost innovation and the existing programs for entrepreneurs require experience as a registered business, creating a gap in capability building for getting started. Education focuses on creation rather than in managing business opportunities, while new professionals struggle with pricing, billing, communicating value and depend on networking. Not everyone is an entrepreneur, but all need to manage their businesses. As an outcome, a service system is proposed: Listo! a series of services to support freelance designers and filmmakers in Colombia to gain the capabilities for running and growing their business in their shift from academia to work life. Resumen: El objetivo de la presente tesis es mapear las oportunidades para el diseño de servicios en las Industrias Creativas en Colombia que funcionen como puente entre la academia y la práctica profesional, para proporcionar condiciones que ayuden a generar un mercado de trabajo más saludable y la creación de negocios para los nuevos y futuros profesionales. El estudio considera las políticas y estadísticas de las industrias creativas para encontrar oportunidades y profundiza en la comprensión de las necesidades y motivaciones de los profesionales independientes del diseño, creación audiovisual y los artistas independientes. Como estos últimos dependen de un ecosistema diferente, los resultados se centraron en proponer un sistema de servicios para diseñadores y creadores audiovisuales. La investigación comenzó con una revisión bibliográfica para una comprensión conceptual de las Industrias Creativas en un contexto internacional e histórico, y luego se centró en la clasificación, las estadísticas y las características de los sectores de las Industrias Creativas en Colombia. El análisis continuó con la exploración de estudios de caso internacionales y nacionales centrados en programas de emprendimiento vinculados a universidades. Además, la investigación de campo utilizó un enfoque de diseño centrado en las personas, recopilando datos cuantitativos y cualitativos de estudiantes, graduandos y trabajadores independientes en Bogotá, Cali y Popayán a través de encuestas y entrevistas, involucrando a las partes interesadas en procesos de ideación y creación de prototipos de servicios. El análisis muestra que los creativos necesitan desarrollar capacidades en materia de emprendimiento, aumentar sus conocimientos sobre derechos de autor y diversificar las actividades a lo largo de la cadena de valor. A la vez que un vínculo más fuerte con el mundo académico ayudaría a impulsar la innovación, los programas existentes para emprendedores requieren experiencia como empresa registrada, generando así una brecha de aprendizaje de las habilidades necesarias para incursionar en el emprendimiento. La educación se centra en la creación más que en la gestión de las oportunidades de negocio, mientras que los nuevos profesionales tienen dificultades para fijar los precios, facturar, comunicar el valor y dependen de la creación de redes. No todo el mundo es empresario, pero todos necesitan gestionar sus negocios. Como resultado, se propone un sistema de servicios: Listo!, una serie de servicios para apoyar a los diseñadores y creadores audiovisuales independientes de Colombia para que adquieran las capacidades necesarias para gestionar y hacer crecer su negocio en su paso de la academia a la vida laboral.

Abstract: Power systems have been dominated by synchronous generators for more than a century. The power system stability has been classically categorized with respect to the dynamics and interactions of the synchronous generator. The classic categories are rotor-angle, frequency, and voltage stability. However, due to the recent high penetration of inverterbased generators such as solar panels and wind turbines, instabilities have arisen outside the spectrum of the classical power system definitions. Therefore, in 2020, the slowinteraction converter-driven stability has been included in the power system stability classification by the IEEE Power System Dynamic Performance Committee. This instability has been observed in real-life cases showing undamped voltage oscillations, which have led to the partial disconnection of power systems. This work focuses on this recently classified instability whose investigation is in the early stages regarding its cause, detection and prevention. Therefore, this work proposes a methodology for the detection and prediction of this instability. This methodology is based on time-domain simulations, the computation of eigenvalues of the power system and the participation factors of oscillatory modes. The proposed tool has been effective in not only detecting but also anticipating the onset of converter-driven instability in operational scenarios with long-term voltage instability. The elements causing the instability are identified using the participation factors, which facilitate the tuning of inverter-based generators controls. Thereby, it is possible to mitigate the converter-driven instability before its manifestation and thus avoid undesired disconnection of generation units, or in the worst case, a potential system collapse. Resumen: Los sistemas de energía han estado dominados por generadores síncronos durante más de un siglo. La estabilidad del sistema de potencia se ha categorizado clásicamente con respecto a la dinámica y las interacciones del generador síncrono. Las categorías clásicas son el ángulo del rotor, la frecuencia y la estabilidad de voltaje. Sin embargo, debido a la reciente alta penetración de generadores basados en inversores, como paneles solares y turbinas eólicas, han surgido inestabilidades fuera del espectro de las definiciones clásicas de sistemas de energía. Por lo tanto, en 2020, la estabilidad impulsada por el convertidor de interacción lenta ha sido incluida en la clasificación de estabilidad del sistema de energía por el Comité de Desempeño Dinámico del Sistema de Energía de IEEE. Esta inestabilidad se ha observado en casos de la vida real que muestran oscilaciones de tensión no amortiguadas, que han provocado la desconexión parcial de los sistemas eléctricos. Este trabajo se centra en esta inestabilidad recientemente clasificada cuya investigación se encuentra en etapas tempranas en cuanto a su causa, detección y prevención. Por tanto, este trabajo propone una metodología para la detección y predicción de esta inestabilidad. Esta metodología se basa en simulaciones en el dominio del tiempo, el cálculo de los valores propios del sistema eléctrico y los factores de participación de los modos oscilatorios. La herramienta propuesta ha sido eficaz no solo para detectar sino también para anticipar el inicio de la inestabilidad impulsada por el convertidor en escenarios operativos con inestabilidad de voltaje a largo plazo. Los elementos que causan la inestabilidad se identifican utilizando los factores de participación, que facilitan el ajuste de los controles de los generadores basados en inversores. De esta manera, es posible mitigar la inestabilidad impulsada por el convertidor antes de su manifestación y así evitar la desconexión no deseada de las unidades de generación o, en el peor de los casos, un colapso potencial del sistema.