We consider the problem of optimization and decision-making in various settings involving complex systems. In particular, we consider specific problems in decentralized finance which we address employing insights from mathematical finance, in course-mode selection that we solve by applying mixed-integer programming, and in social networks that we approach using tools from graphical game theory.In the first part of the thesis, we model and analyze fixed spread liquidation lending in DeFi as implemented by popular pooled lending protocols such as AAVE, JustLend, and Compound. Empirically, we observe that over 70% of liquidations occur in the absence of any downward price jumps. Then, assuming the borrowers monitor their loans with exponentially distributed horizons, we compute the expected liquidation cost incurred by the borrowers in closed form as a function of the monitoring frequency. We compare this cost against liquidation data obtained from AAVE protocol V2, and observe a match with our model assuming the borrowers monitor their loans five to six times more often than they interact with the pool. Such borrowers must balance the financing cost against the likelihood of liquidation. We compute the optimal health factor in this situation assuming a financing rate for the collateral. Empirically, we observe that borrowers are often more conservative compared to model predictions, though on average, model predictions match with empirical observations. In the second part of the thesis, we consider the problem of hybrid scheduling that was faced by Columbia Business School during the Covid-19 pandemic and describe the system that we implemented to address it. The system allows some students to attend in-person classes with social distancing, while their peers attend online, and schedules vary by day. We consider two variations of this problem: one where students have unique, individualized class enrollments, and one where they are grouped in teams that are enrolled in identical classes. We formulate both problems as mixed-integer programs. In the first setting, students who are scheduled to attend all classes in person on a given day may, at times, be required to attend a particular class on that day online due to social distancing constraints. We count these instances as “excess.” We minimize excess and related objectives, and analyze and solve the relaxed linear program. In the second setting, we schedule the teams so that each team’s in-person attendance is balanced over days of week and spread out over the entire term. Our objective is to maximize interaction between different teams. Our program was used to schedule over 2,500 students in student-level scheduling and about 790 students in team-level scheduling from the Fall 2020 through Summer 2021 terms at Columbia Business School. In the third part of the thesis, we consider a social network, where individuals choose actions which optimize utility which is a function of their neighbors’ actions. We assume that a central authority aiming to maximize social welfare at equilibrium can intervene by paying some cost to shift individual incentives, and that the cost is upper bounded by a budget. The intervention that maximizes the social welfare can be computed using the spectral decomposition of the adjacency matrix of the graph, yet this is infeasible in practice if the adjacency matrix is unknown. We study the question of designing intervention strategies for graphs where the adjacency matrix is unknown and is drawn from some distribution. For several commonly studied random graph models, we show that the competitive ratio of in intervention proportional to the first eigenvector of the expected adjacency matrix, approaches 1 in probability as the graph size increases. We also provide several efficient sampling-based approaches for approximately recovering the first eigenvector when we do not know the distribution. On the whole, our analysis compares three categories of interventions: those which use no data about the network, those which use some data (such as distributional knowledge or queries to the graph), and those which are fully optimal. We evaluate these intervention strategies on synthetic and real-world network data, and our results suggest that analysis of random graph models can be useful for determining when certain heuristics may perform well in practice.

La sélection de l'information intégrée à l'agenda politique représente une étape décisive pour les politiciens, influencée par des contraintes telles que les ressources limitées et la dispersion de l'attention nécessaire pour résoudre les problèmes prioritaires. Cette dynamique souligne l'importance croissante du rôle de la capacité de l'État dans la conception et la formation de l'agenda politique, un sujet sous-étudié dans la littérature sur les politiques publiques. Cette thèse se focalise précisément sur une question qui a été peu explorée jusqu'à présent : quelle est l'influence de la capacité de l'État sur la formation de l'agenda politique ? Afin de répondre à cette question, trois chapitres empiriques ont été développés, visant à examiner la dynamique complexe entre la capacité de l'État et l'agenda politique au Brésil. Le premier article (chapitre 3) met en lumière les mécanismes de changement de l'agenda législatif pendant les conflits agro-environnementaux au niveau national. Il souligne comment la capacité du secteur agricole et de l'environnement influence les informations intégrées dans l’agenda politique. L'article conclut que les secteurs agricoles dotés d'une plus grande capacité étatique ont tendance à bloquer les sujets environnementaux de l'agenda politique, mais que sous la pression médiatique, ils peuvent être amenés à concéder temporairement à ceux avec une capacité moindre. Le deuxième article (chapitre 4) examine l'influence de la capacité étatique sur l'utilisation de l'information scientifique pendant la pandémie de COVID-19 au niveau régional. Il révèle que les États avec une forte capacité épidémiologique ont tendance à privilégier l'information scientifique dans leur agenda politique, même lorsque d'autres approches sont disponibles. L'article souligne également que la capacité épidémiologique des États devient cruciale pour déterminer le type d'information intégrée dans l'agenda politique, en particulier en période de crise. Le troisième article de cette thèse (chapitre 5) explore l’influence de l'opinion publique sur la gravité des mesures prises lors de la pandémie de COVID-19 au niveau régional. Il met en évidence que les États avec des capacités épidémiologiques plus fortes tendent à accorder une plus grande importance aux préoccupations de santé publique dans leurs décisions politiques, tandis que ceux avec des capacités moindres peuvent être davantage influencés par les préoccupations économiques. L'article conclut que la capacité étatique influence la manière dont les ii gouvernements interprètent et utilisent l'information de l'opinion publique pour définir leur agenda politique. En conclusion, ces articles démontrent le rôle crucial de la capacité étatique dans la formation de l'agenda politique. Cette capacité influence la sélection et la priorisation de l'information, ce qui en retour détermine les sujets abordés par les décideurs politiques. Comprendre le fonctionnement de la capacité étatique est donc indispensable pour appréhender pleinement les mécanismes de la formation de l'agenda politique. / The selection of information integrated into the political agenda represents a crucial step for politicians, influenced by constraints such as limited resources and the dispersion of attention needed to address priority issues. This dynamic increasingly emphasizes the importance of the state's capacity in shaping and forming the political agenda, a topic under-explored in the literature on public policy. This thesis specifically focuses on a question that has been relatively unexplored until now: what is the influence of state capacity on the formation of the political agenda? To address this question, three empirical chapters were developed, aiming to examine the complex dynamics between state capacity and the political agenda in Brazil. The first article (Chapter 3) highlights the mechanisms of legislative agenda change during agroenvironmental conflicts at the national level. It emphasizes how the capacity of the agricultural and environmental sectors influences the information integrated into the political agenda. The article concludes that agricultural sectors with greater state capacity tend to block environmental issues from the political agenda, but under media pressure, they may be temporarily compelled to concede to those with lesser capacity. The second article (Chapter 4) examines the influence of state capacity on the use of scientific information during the COVID-19 pandemic at the regional level. It reveals that states with strong epidemiological capacity tend to prioritize scientific information in their political agenda, even when other approaches are available. The article also emphasizes that the epidemiological capacity of states becomes crucial in determining the type of information integrated into the political agenda, especially during times of crisis. The third article of this thesis (Chapter 5) explores the influence of public opinion on the severity of measures taken during the COVID-19 pandemic at the regional level. It highlights that states with stronger epidemiological capacities tend to prioritize public health concerns more in their policy decisions, while those with weaker capacities may be more influenced by economic concerns. The article concludes that state capacity influences how governments interpret and use public opinion information to shape their political agenda. In conclusion, these articles demonstrate the crucial role of state capacity in shaping the political agenda. This capacity influences the selection and prioritization of information, which in turn determines the topics addressed by policymakers. Understanding the functioning of state capacity is therefore essential for fully grasping the mechanisms of agenda formation.

La presente investigación se enfocó en el impacto que tuvo el COVID-19 en el sector servicios específicamente en el inmobiliario. Por tanto, se planteó como objetivo general analizar el impacto económico y financiero de las estrategias ante el COVID-19 de la Inmobiliaria Ingenierías Energías y Medio Ambiente SAC años 2019 a 2022. La metodología de estudio empleada fue cuantitativa, de tipo aplicada y nivel descriptivo, a su vez, un diseño experimental de corte de transversal. Así mismo, la población sujeta de estudio es la inmobiliaria teniendo como muestra a la información financiera para la elaboración de indicadores financieros, implementando estrategias para la toma de decisiones. Por ello, se utilizaron instrumentos como la entrevista y el análisis documental. Los resultados evidenciaron la elaboración de un diagnóstico de la situación económica financiera de la Inmobiliaria Ingeniería Energía y Medio Ambiente SAC, con esta información se observó una rentabilidad y liquidez no significativa; además se analizaron las medidas de reactivación económica empresarial aplicadas por la inmobiliaria durante la pandemia las cuales fueron estrategias operativas y de mercado, así pues, se evaluó el efecto por el COVID-19 en los estados financieros de los años 2021 al 2022 un ligero mejoramiento en sus ratios de rentabilidad y liquidez. Por lo tanto, la elaboración de estrategias complementarias nos va permitir enfrentar la situación económica de la Inmobiliaria Ingeniería Energía y Medio Ambiente SAC para el año 2023. / The present investigation focused on the impact that COVID-19 had on the services sector, specifically on real estate. Therefore, it has been proposed as a general objective to analyze the economic and financial impact of the strategies before the Covid-19 of the Inmobiliaria Ingenierías Energías y Medio Ambiente SAC years 2019 to 2022. The study methodology used was quantitative, of an application type and level descriptive, in turn, a cross-sectional experimental design. Likewise, the population subject to study is real estate, having as a sample the financial information for the elaboration of financial indicators, implementing strategies for decision making. For this reason, instruments such as the interview and documentary analysis were used. The results evidenced the elaboration of a diagnosis of the financial economic situation of the Inmobiliaria Ingeniería Energía y Medio Ambiente SAC, with this information a non-significant profitability and liquidity was observed; In addition, the business economic reactivation measures applied by the real estate company during the pandemic were analyzed, which were operational and market strategies, thus, the effect of Covid 19 on the financial statements for the years 2021 to 2022 was evaluated, a slight improvement in their profitability and liquidity ratios. Therefore, the elaboration of complementary strategies will allow us to face the economic situation of the Inmobiliaria Ingeniería Energía y Medio Ambiente SAC for the year 2023.

Систематизированы специфические особенности торговой недвижимости в условиях стабильной и нестабильной рыночной среды, выявлены факторы влияющие на изменение стоимости объекта в условиях неопределенности и обоснован усовершенствованный подход к определению рыночной стоимости объекта торгового назначения, основанный на учете влияния факторов внешней среды на стоимость объектов доходной недвижимости в зависимости от специфики данного сегмента рынка недвижимости. / The features of real estate trade in a stable and international market environment are systematized, factors influencing changes in the value of an object under conditions of uncertainty are identified, and a modernized approach to determining the market value of a real estate object is substantiated, based on taking into account external environmental factors on the cost of profitable real estate, depending on the specifics this segment of the real estate market.

This study investigated the associations between sleep patterns and singing voice quality in 231 adult singers of various skill levels across the United States. The four-part survey using a general questionnaire on demographics, musical background, vocal health, and three established survey instruments: the Pittsburgh Sleep Quality Index (PSQI), the Singing Voice Handicap Index-10 (SVHI-10), and the Epworth Sleepiness Scale (ESS) found that while scores were worse than normative values for the PSQI and the SVHI-10, a Pearson correlation between the two showed a moderate association. A linear regression also yielded that 8.9% of the variance in SVHI-10 scores could be predicted from PSQI scores. While further research is needed in this area, this study suggests that the amount of sleep needed for an optimal singing voice may be different from the amount needed to feel well-rested for some singers. Moreover, singers may overestimate the influence of sleep on their singing voices.

Healthcare workers (HCWs) and public safety personnel (PSP) are at an elevated risk for adverse mental health outcomes, including PTSD, anxiety, depression, and increased suicidality. Workplace challenges and burdens were exacerbated by the COVID-19 pandemic, which further highlighted the physical and mental health vulnerabilities of HCWs and PSP. As a result, there has been a growing interest from mental health professionals and researchers in understanding the unique stresses and mental health risks these individuals face. Moral injury (MI), a phenomenon linked to the unique experiences of HCWs and PSP, has been associated with adverse mental health outcomes. Cognitive impairments, such as memory disturbances, are also frequently observed in these populations. This thesis explored the relation between MI and memory disturbances and how this relation was impacted by emotion regulation (ER) and self-compassion (SC). In addition, we investigated how SC and ER influenced the relation between MI and adverse childhood experiences (ACEs). In the first study of this thesis, we explored these relations through a series of correlational, moderated mediation analyses of self-report measures collected among HCWs and PSP during the COVID-19 pandemic. These analyses revealed significant relations between MI and memory disturbances, where higher levels of moral injury were associated with elevated levels of memory disturbances, particularly in relation to subscales of guilt and shame. Interestingly, these effects were moderated by ER and mediated by SC at high levels of ER difficulties. In the second study of the thesis, we conducted various correlational analyses as well as explored the relation between MI and ACEs alongside the impacts of SC and ER through moderated mediation analysis. The analyses in this study revealed significant relations between MI and ACEs regarding the mediating effect of SC and the moderating effect of ER at medium and low levels of ER difficulties. / Thesis / Master of Science (MSc)

This thesis project explores how interactive technologies can facilitate a sense of social connectedness with others whilst remotely located. While studying the way humans use rituals for emotional management, I focused my interest on the act of commensality because it is one of the oldest and most important rituals used to foster togetherness among families and groups of friends. Dining with people who do not belong to the same household is of course hard during a global pandemic, just like many of the other forms of social interactions that were forcibly replaced by the use of technological means such as video-chat apps, instant messaging and perhaps an excessive use of social networking websites. These ways of staying connected, however, lack the subtleties of real physical interaction, which I tried to replicate with my prototype system, which consists of two sets of a lamp and a coaster which enable to communicate through light and tactile cues. The use of such devices creates a new kind of ritual based on the simultaneous use of the devices by two people, thus enabling a new and original form of commensality that happens through a shared synchronized experience.

Syfte: Syftet med denna studie är att belysa hur den kris som Covid-19 pandemin skapat harpåverkat hotell och resebyråers digitala taktiska respektive planerade strategiska marknadsföring,samt den krishantering som tillämpats av företagen under denna pandemin och de lärdomar dedragit av denna kris.Teori: Den teoretiska referensramen för denna studie innefattar marknadsförings-, krishanteringsoch organisationsteori. Inom marknadsföring har SCRM samt RACE marketing planningframework modellerna tillämpats och inom krishantering har krisprocessen och kriskurvanmodellerna. Vad gäller organisationsteori har fokus varit på organisatoriskt lärande och teoriernasingle-, double- och triple-loop learning samt learning in crisis.Metod: Studien omfattar en kvalitativ undersökning av två hotell och två resebyråer grundad på ensemistrukturerad intervjumetod.Slutsatser: Covid-19 pandemin har tvingat respondenterna att vara flexibla och att göra kortsiktigaanpassningar av sina marknadsföringsmetoder. Den taktiska marknadsföringen har skett genom enökad användning av digitala kanaler som lyhört anpassats till kundernas behov av hälsa ochsäkerhet. Det var ännu för tidigt för att bedöma eventuella förändringar i den strategiskamarknadsföringen men några respondenter förväntade sig ett större fokus på värde begrepp somhälsa och trygghet. Samtliga respondenter har i praktiken ägnat sig åt krishantering och de flestarespondenterna hade någon form av förberedda krisplaner, som dock inte varit anpassade till en såomfattande och djup kris som den förevarande. Samtliga respondenter verkar ha fått en större insikti vikten av att ha en effektiv och tät intern och extern kriskommunikation. Den yttre situationen harskapat ett stort tryck på respondenterna och har givit dem lärdomar som de möjligen inte hade fåttunder normala omständigheter, inklusive att på ett flexibelt och lättrörligt sätt anpassa sig till nyaoch föränderliga situationer. Även om Covid-19 pandemin framkallat mycket stress och ångest såhar den även haft positiva effekter som kan ge upphov till mer varaktiga förändringar. / Purpose: The purpose of this study is to shed some light on how some hotels and travel agenciesin the Swedish tourism and hospitality industry have adapted to and managed the effects of theCovid-19 pandemic, particularly in terms of strategic and tactical digital marketing as well as crisismanagement, and the lessons learned from this crisis.Theory: The theoretical foundations for this paper include digital marketing theories, crisismanagement and organizational theory. In marketing theory, the SCRM and the RACE marketingplanning framework models have been applied and in terms of crisis management, the crisismanagement process as well as the crisis curve models have been applied. In terms oforganizational theory, focus has been on organizational learning and the theories single-, doubleand triple-loop learning as well as learning in crisis.Method: This study is a qualitative study of two hotels and two travel agencies based on semistructured interviews.Conclusions: This study demonstrates that the Covid-19 pandemic has forced the respondents tobe flexible and to make short-term adjustments to their marketing tactics. The tactical marketinghas included an increased use of digital channels and an adaptation of their marketing to theircustomers' needs for health and safety. It was too early to assess any changes in strategicmarketing, but some respondents planned to place a greater focus on value concepts such ashealth and safety. In practice, all respondents were engaged in crisis management and most of therespondents had some form of prepared crisis plans, which, however, were not adapted to such anextensive and protracted crisis as the Covid-19 pandemic. All respondents seemed to have gainedgreater insight into the importance of having effective and frequent internal and external crisiscommunication. The external situation has put a great deal of pressure on the respondents and hasgiven them lessons that they might not have acquired under normal circumstances, including acapacity to adapt flexibly and easily to new and changing situations. Although the Covid-19pandemic has caused a lot of stress and anxiety, it has also had positive effects that could triggerchanges in their longer term strategic marketing.

Covid-19 pandemin skapade många begränsningar i det fysiska mötet för företag i Sverige. Problematiken för de företag som inte kunde erbjuda sin produkt på samma sätt digitalt var det som skapade ett intresse att genomföra denna studie. Många företag fick göra ett skifte och fokusera mer på de digitala verktygen under den här tiden. Därför valde gruppen att fördjupa sig i hur företag på Instagram arbetar med sitt innehåll för att skapa engagemang. Frågorna som besvarades togs fram med syftet att skapa en uppfattning kring vilken av de tre framtagna inläggs kategorierna som skapar högst engagemang, rationella inlägg, interaktionella inlägg eller transaktionella inlägg. Samt hur innehållet på Instagram kan förändras beroende på om det fysiska mötet är begränsat eller ej.En kvalitativ fallstudie på Liseberg genomfördes i form av dokumentanalys på företagets Instagramkonto. Resultatet kopplades därefter samman med den tidigare forskningen inom engagemang, digital marknadsföring, sociala medier marknadsföringsstrategi och Social Exchange Theory. Studien är avgränsad till att endast mäta engagemang baserat på gilla-markeringar och kommentarer. Vikten av att ett företag behöver engagemang för att vara konkurrenskraftiga klarläggs samt relevans att företag finns på sociala medier. Resultatet visade att de transaktionella inläggen hade betydligt högst engagemang, men även att de interaktionella inläggen skapade högt engagemang. Förslagsvis borde företag under perioderna de har nedstängt fokusera just på dessa två kategorier som uppmanar till att skapa engagemang i form av gilla-markeringar och kommentarer. Studien visade också hur Liseberg anpassade mängden samt innehållet av deras inlägg under de olika perioderna för att hålla sig aktuella med vad besökarna efterfrågade. Studien är skriven på svenska. / Covid-19 pandemic created a lot of limitations for companies when it came to the physical meeting. The problem that occurred when companies no longer were able to offer their product in reality created an interest in this study. Many companies had to make a shift and focus more on digital tools during this time. Therefore, this group chose to dive into how a company on Instagram works with their content to create engagement. The questions that were answered were developed with the aim of creating knowledge about which of the three developed post categories create the highest engagement, rational posts, interactional posts or transactional posts. As well as how the content on Instagram may change depending on whether the physical meeting is limited or not.A qualitative case study on the amusement park Liseberg was carried out in the form of document analysis on @Lisebergab Instagram. The result was then connected with the previous research on engagement, digital marketing, social media marketing strategy and the Social Exchange Theory. The study is limited to only measuring engagement based on likes and comments. The importance of companies needing engagement to be competitive is clarified, as well as the relevance of companies being on social media. The transactional posts received the highest engagement, but it was also shown that it is not financially sustainable to focus on this too much.The results showed that transactional posts had the highest engagement, but also that interactive posts created high engagement. It is suggested that companies during periods of shutdown should focus on these two categories that encourage engagement in the form of likes and comments. This study also showed how Liseberg adapted the amount and content of their posts during different periods to stay current with what visitors demanded from the company. Following will this paper be written in swedish.

The phenomenon of educational inequality on access to physical resources in the Highveld Ridge East Circuit of Mpumalanga was investigated in the study. Since the COVID-19 worldwide pandemic had affected education on a global scale, South Africa included, it became necessary to incorporate this new development into the emerging design that unfolded. The study explored the impact of access to physical resources in three public schools. The aim of the investigation was to ascertain how educational disparities on access to physical resources manifested at the chosen research sites, especially during the COVID-19 pandemic. A qualitative research approach was utilised comprising of a multiple case study design. The study reported how the principal and deputy principals viewed educational inequality on access to physical resources from a management perspective, while educators provided insight on the effect of this phenomenon on the teaching and learning process. Observations, individual interviews involving the principal and deputy principals as participants, and focus group interviews involving the teachers, as well as the scrutiny of relevant official documents provided the empirical data for this investigation. All research participants were purposively selected, as a full staff complement was unavailable at the research sites during the pandemic. The results that emerged from the study indicated that educational inequality was prevalent in these public schools. The dearth of resources, and in some instances basic essential resources, had a marked impact on the management as well as the teachers and students at these schools. A significant point to consider was how ill-equipped the public schools in this area were to deal with education during a global pandemic. The backlog of the inequities on access to physical resources needed to be addressed as a matter of dire urgency if the country had any hope of salvaging the education process even at the most basic level. The recommendations in the conclusion of the study are desperate pleas for help in assisting the country, especially the previously marginalised, to move forward in the worst of times. / Educational Management and Leadership / M. Ed. (Education Management)