Cette thèse traite de processus de détérioration en théorie du risque et en biomathématique.<p><p>En théorie du risque, le processus de détérioration étudié est celui des sinistres supportés par une compagnie d'assurance.<p><p>Le premier chapitre examine la distribution de Markov-Polya comme loi possible pour modéliser le nombre de sinistres et établit certains liens avec la famille de lois de Katz/Panjer. Nous construisons la loi de Markov-Polya sur base d'un modèle de survenance des sinistres et nous montrons qu'elle satisfait une récurrence élégante. Celle-ci permet notamment de déduire un algorithme efficace pour la loi composée correspondante. Nous déduisons la famille de Katz/Panjer comme famille limite de la loi de Markov-Polya.<p><p>Le second chapitre traite de la famille dite "Lagrangian Katz" qui étend celle de Katz/Panjer. Nous motivons par un problème de premier passage son utilisation comme loi du nombre de sinistres. Nous caractérisons toutes les lois qui en font partie et nous déduisons un algorithme efficace pour la loi composée. Nous examinons également son indice de dispersion ainsi que son comportement asymptotique. <p><p>Dans le troisième chapitre, nous étudions la probabilité de ruine sur horizon fini dans un modèle discret avec taux d'intérêt positifs. Nous déterminons un algorithme ainsi que différentes bornes pour cette probabilité. Une borne particulière nous permet de construire deux mesures de risque. Nous examinons également la possibilité de faire appel à de la réassurance proportionelle avec des niveaux de rétention égaux ou différents sur les périodes successives.<p><p>Dans le cadre de processus épidémiques, la détérioration étudiée consiste en la propagation d'une maladie de type SIE (susceptible - infecté - éliminé). La manière dont un infecté contamine les susceptibles est décrite par des distributions de survie particulières. Nous en déduisons la distribution du nombre total de personnes infectées à la fin de l'épidémie. Nous examinons en détails les épidémies dites de type Markov-Polya et hypergéométrique. Nous approximons ensuite cette loi par un processus de branchement. Nous étudions également un processus de détérioration similaire en théorie de la fiabilité où le processus de détérioration consiste en la propagation de pannes en cascade dans un système de composantes interconnectées. <p><p><p> / Doctorat en Sciences / info:eu-repo/semantics/nonPublished

Cette thèse propose une étude mathématique des stratégies de vaccination.La partie I présente le cadre mathématique, notamment le modèle à compartiments Susceptible - Infected – Recovered.La partie II aborde les techniques mathématiques de type contrôle optimal employées afin de trouver une stratégie optimale de vaccination au niveau de la société. Ceci se fait en minimisant le coût de la société. Nous montrons que la fonction valeur associée peut avoir une régularité plus faible que celle attendue dans la littérature. Enfin, nous appliquons les résultats à la vaccination contre la coqueluche.La partie III présente un modèle où le coût est défini au niveau de l'individu. Nous reformulons le problème comme un équilibre de Nash et comparons le coût obtenu avec celui de la stratégie sociétale. Une application à la grippe A(H1N1) indique la présence de perceptions différentes liées à la vaccination.La partie IV propose une implémentation numérique directe des stratégies présentées. / This thesis propose a mathematical analysis of the vaccination strategies.The first part introduces the mathematical framework, in particular the Susceptible – Infected – Recovered compartmental model.The second part introduces the optimal control tools used to find an optimal vaccination strategy from the societal point of view, which is a minimizer of the societal cost. We show that the associated value function can have a less regularity than what was assumed in the literature. These results are then applied to the vaccination against the whooping cough.The third part defines a model where the cost is defined at the level of the individual. We rephrase this problem as a Nash equilibrium and compare this results with the societal strategy. An application to the Influenza A(H1N1) 2009-10 indicates the presence of inhomogeneous perceptions concerning the vaccination risks.The fourth and last part proposes a direct numerical implementation of the different strategies.

Social networks play an important role in disseminating a piece of information in a population. Companies advertising a newly launched product, movie promotion, political campaigns, social awareness campaigns by governments, charity campaigns by NGOs and crowd funding campaigns by entrepreneurs are a few examples where an entity is interested in disseminating a piece of information in a target population, possibly under resource constraints. In this thesis we model information diffusion in a population using various epidemic models and study optimal campaigning strategies to maximize the reach of information. In the different problems considered in this thesis, information epidemics are modeled as the Susceptible-Infected, Susceptible-Infected-Susceptible, Susceptible-Infected-Recovered and Maki Thompson epidemic processes; however, we modify the models to incorporate the intervention made by the campaigner to enhance information propagation. Direct recruitment of individuals as spreaders and providing word-of-mouth incentives to the spreaders are considered as two intervention strategies (controls) to enhance the speed of information propagation. These controls can be implemented by placing advertisements in the mass media, announcing referral/cash back rewards for introducing friends to a product or service being advertised etc. In the different problems considered in this thesis, social contacts are modeled with varying levels of complexity---population is homogeneously mixed or follows heterogeneous mixing. The solutions to the problems which consider homogeneous mixing of individuals identify the most important periods in the campaign duration which should be allocated more resources to maximize the reach of the message, depending on the system parameters of the epidemic model (e.g., epidemics with high and low virulence). When a heterogeneous model is considered, apart from this, the solution identifies the important classes of individuals which should be allocated more resources depending upon the network considered (e.g. Erdos-Renyi, scale-free) and model parameters. These classes may be carved out based on various centrality measures in the network. If multiple strategies are available for campaigning, the solution also identifies the relative importance of the strategies depending on the network type. We study variants of the optimal campaigning problem where we optimize different objective functions. For some of the formulated problems, we discuss the existence and uniqueness of the solution. Sometimes our formulations call for novel techniques to prove the existence of a solution.

Obesity and obesity-related diseases – such as type 2 diabetes – have become the most crucial indicators of population health in the 21st century. Formerly understood as ‘diseases of affluence’, obesity is now prevalent in the Global South posing serious risk to socioeconomic development. This is particularly true for rapidly developing countries where nutrition transitions are most apparent. There are many factors which impact on risk of obesity (e.g. gender, culture, environment, socioeconomic status, biological determinants). The problem is further aggravated within small island developing states where food security is exacerbated by factors associated with globalization and development. The thesis examines the surge of obesity and type 2 diabetes within Caribbean populations, using Barbados as a case study. A holistic approach was applied using an ecological health model. Moving away from the lifestyle model, the theoretical framework underpinning included sub-theories (e.g. social constructivism, feminism, post-colonial theory, concepts of memory and trauma).

The dynamics of many aspects of social behaviour, such as spread of fads and fashion, collective action, group decision-making, homophily and disagreement, have been captured by mathematical models. The power of these models is that they can provide novel insight into the emergent dynamics of groups, e.g. 'epidemics' of memes, tipping points for collective action, wisdom of crowds and leadership by small numbers of individuals, segregation and polarisation. A current weakness in the scientific models is their sheer number. 'New' models are continually 'discovered' by physicists, engineers and mathematicians. The models are analysed mathematically, but very seldom provide predictions that can be tested empirically. In this work, we provide a framework of simple models, based on Lotka's original idea of using chemical reactions to describe social interactions. We show how to formulate models for social epidemics, social recovery, cycles, collective action, group decision-making, segregation and polarisation, which we argue encompass the majority of social dynamics models. We present an open-access tool, written in Python, for specifying social interactions, studying them in terms of mass action, and creating spatial simulations of model dynamics. We argue that the models in this article provide a baseline of empirically testable predictions arising from social dynamics, and that before creating new and more complicated versions of the same idea, researchers should explain how their model differs substantially from our baseline models. / Matematiska modeller kan hjälpa oss att förstå många typer av sociala fenomen, som ryktesspridning, spridning av memes, gruppbeslut, segregation och radikalisering. Det finns idag otaliga modeller för sociala beteenden hos människor och djur, och fler presenteras kontinuerligt. Det stora antalet modeller försvårar navigering inom forskningsfältet, och många av modellerna är dessutom komplicerade och svåra att verifiera genom experiment. I detta arbete föreslås ett ramverk av grundläggande modeller, som var och en modellerar en aspekt av socialt beteende; det gäller sociala epidemier, cykler, gemensamt handlande, gruppbeslut, segregation och polarisering. Vi menar att dessa modeller utgör majoriteten av de verifierbara aspekter av socialt beteende som studeras, och att de bör behandlas som en utgångspunkt när en ny modell ska introduceras. Vilka av mekanismerna från utgångspunkten finns representerade i modellen? Skiljer den sig ens nämnvärt från utgångspunkten? Genom att ha en god förståelse för grundmodellerna, och genom att förklara på vilket sätt en ny modell skiljer sig från dem, kan forskare undvika att presentera modeller som i praktiken är mer komplicerade varianter av sådana som redan finns. I detta arbete visar vi hur dessa grundläggande modeller kan formuleras och studeras. Modellerna bygger på enkla regler om vad som händer när individer i en befolkning möter varandra. Till exempel, om en person som har vetskap om ett rykte träffar någon som inte har det, kan ryktet spridas vidare. Därför har antaganden om vilka personer som kan träffa varandra stor påverkan på de resultat som modellerna ger. I detta arbete studeras varje modell med två olika metoder: i den ena har alla personer i befolkningen samma sannolikhet att träffa varandra, i den andra representeras befolkningen av ett rutnät, där varje plats motsvarar en individ. I den senare har alltså varje person ett begränsat antal grannar att interagera med. Vilken av dessa två metoder man väljer har stor betydelse för vilka beteenden modellerna förutspår. Som ett komplement till detta arbete presenteras ett verktyg i form av ett Python-program som utför analysen av modellerna. Detta kan användas för att undersöka grundmodellerna som presenteras i detta arbete, men också för att formulera och analysera nya modeller på samma sätt. På det viset kan nya modeller enkelt jämföras mot grundmodellerna. Verktyget är användbart både som introduktion för de som är nya inom social dynamik, men också för de forskare som som vill ta fram nya modeller och föra forskningsfältet vidare.

The prevalence of Hepatitis C Virus (HCV) in the US is estimated at 3.5 million with 18,153 deaths in 2016. It is the most common bloodborne infection, with a higher age-adjusted mortality rate than Hepatitis B Virus or Human Immunodeficiency Virus. Without treatment, nearly 1.1 million people will die from HCV by 2060. About 41,200 new cases of HCV were reported in 41 states in the US in 2016. The reported cases of acute HCV in 2016 is 2.3 per 100,000 in Tennessee, which is more than twice the national goal set by Healthy People 2020. This is a descriptive study to ascertain the HCV prevalence and usefulness of screening in medical outreach settings (MO) compared to indigent healthcare clinics (IHC) in northeast Tennessee. This study period was from April 2017 – February 2019. Participants (n=250), were adults, who engaged in routine, opt-out HCV testing at 4 IHC and 3 MO sites in the Tri-Cities, TN region. During the screening, demographic information- age, gender, race- were collected and the de-identified data were analyzed using Statistical Analysis System (SAS 9.3) to perform a descriptive analysis. Also, several discrete Chi-Square tests of independence between the demographic variables, screening locations, and HCV antibody prevalence was conducted. A total of 250 clients were screened for HCV. The majority of clients screened were non-Hispanic whites 228 (91.20%); females 136 (54.40%); young adults 131 (52.40%) and at IHC clinics 187 (74.80%). Screening showed HCV antibody prevalence of 14.8%. The majority of positive cases were non-Hispanic whites 36 (97.30%; P=0.1561); females 19 (51.35%; P=0.6867) and young adults 23 (62.16%; P=0.286). The prevalence at the IHC clinics and MO settings were 36 (97.30%; P=0.0006) and 1(2.70%) respectively. This analysis shows the higher yield of targeted HCV screening at IHC clinics. Focused HCV screening is critical in the era of opioid epidemic, particularly when direct-acting antiviral agents (DAAs) which offer a Sustained Virologic Response (SVR) rate of more than 90% are available. The use of case control or cohort study designs to establish causality is recommended for improving focused HCV screening.

Motivés par la demande croissante de services de santé améliorés et à distance, qui tend à augmenter notamment avec une population de plus en plus âgée, et la réduction du coût de l'utilisation des infrastructures réseaux, afin d'assurer des applications de santé temps-réel et à faible débit de données, les réseaux de capteurs médicaux sans fil (WBANs) forment encore un domaine de recherche en forte croissance, notamment avec le développement de WBANs coopératifs. Dans ce contexte, en utilisant les utilisateurs du réseau eux-mêmes en tant que relais on pourrait étendre les infrastructures réseaux existantes, tout en améliorant la capacité du réseau et optimisant l'utilisation du spectre radio. Ainsi, les opérateurs réseaux, qui planifient déjà pour l'intégration de l'internet des objets (IoT) et l'informatique en nuage (cloud), devraient aussi penser à créer un nouveau type de réseau ad hoc mobile, où les utilisateurs du réseau sont utilisés comme des stations de base ad hoc simplifiées, afin de partager l'information en temps-réel entre des personnes colocalisées portant des capteurs corporels. Ce nouveau type de réseau est appelé réseau corporel sans fil (BBN: Body-to-Body Network). Dans un BBN, un appareil radio, collecte les données des nœuds capteurs attachés ou portés par une personne, et les transmet à un appareil récepteur situé sur une autre personne du voisinage, afin d'être traitées ou retransmises à d'autres utilisateurs du BBN. le BBN peut trouver des applications dans divers domaines tels que la santé, les sports d'équipe, le militaire, les divertissements, ainsi que des expériences passionnantes des réseaux sociaux. Fonctionnant dans la bande Industrielle, Scientifique et Médicale (ISM), les liaisons de communication dans un BBN seront très sensibles aux interférences entre les différentes technologies qui partagent le spectre radio limité. Ainsi, l'interférence entre ces technologies devient une préoccupation importante pour la conception de protocoles pour l'utilisateur final du BBN. À ce jour, très peu d'études existent, qui effectuent une analyse en profondeur de ce type de scénario implicant le corps humain dans des communications radio. Le problème d'interférence dans un tel système distribué, doit être abordé avec des mécanismes distribués, tels que la théorie des jeux. Les décideurs dans le jeu sont soit les WBANs formant le BBN ou les opérateurs de réseaux qui contrôlent les dispositifs de communication inter-WBAN. Ces dispositifs doivent faire face à des ressources de transmission limitées (bande ISM) ce qui donne lieu à des conflits d'intérêts. Cette thèse vise à explorer les opportunités pour permettre des communications inter-WBANs en assurant le partage du spectre radio par le biais de deux approches. D'abord, l'atténuation des interférences mutuelles et croisées, et par la conception d'un protocole de routage spécifique BBN utilisé dans une application de contrôle de l'expansion d'une épidémie dans les zones de rassemblement de masse, tels que les aéroports. Dans un premier volet, une approche basée sur la théorie des jeux est proposée pour résoudre le problème d'interférence distribué dans les BBNs. Le jeu d'atténuation des interférences socialement conscient des intérêts de la collectivité (SIM) a une double tâche: à l'échelle WBAN, il alloue des canaux ZigBee aux capteurs corporels pour la collecte intra-WBAN des données, et à l'échelle BBN, il alloue les canaux WiFi aux appareils mobiles pour la transmission et le relais des données inter-WBANs. Deux algorithmes, BR-SIM et SORT-SIM, ont été développés pour rechercher les points d'équilibre de Nash du jeu SIM. Le premier (BR-SIM) assure les solutions de meilleure réponse (Best-response) tandis que le second (SORT-SIM) tente d'obtenir un compromis entre des solutions quasi-optimales et un temps de convergence réduit. (...) / Motivated by the rising demand for remote and improved healthcare, while decreasing the cost of using network infrastructures to ensure time and data rate-constrained applications, Wireless Body Area Networks (WBANs) still form a strongly growing research field. Besides, engineers and researchers are investigating new solutions to supplement mobile communications through developing opportunities for cooperative WBANs. In this context, using network users themselves as relays could complement and extend existing infrastructure networks, while improving network capacity and promoting radio spectrum usage. Yet, network operators, that are already planning for the Internet of Things (IoT) and cloud computing technologies integration, should also think about this new possibility of creating a new type of mobile ad hoc network, where network users themselves are used as simplified ad hoc base stations, to fulfill the desire of sharing real-time information between colocated persons carrying body sensors. This emerging type of network is called Body-to-Body Network (BBN). In a BBN, a radio device situated on one person gathers the sensor data from the sensor nodes worn by that person, and transmit them to a transceiver situated on another person in the nearby area, in order to be processed or relayed to other BBN users. BBNs can find applications in a range of areas such as healthcare, team sports, military, entertainment, as well as exciting social networking experiences. Operating in the popular Industrial, Scientific and Medical (ISM) band, the communication links in a BBN will be heavily susceptible to interference between the different radio technologies sharing the limited radio spectrum. Thus, inter-body interference become an important concern for protocol design and quality of service for the BBN end user. Yet, higher layer MAC and networking mechanisms need to be in place to overcome this interference problem. To date, very few studies, that perform in-depth analysis of this type of body-centric scenario, exist. The interference problem in such distributed system, should be tackeled with distributed mechanisms, such as Game Theory. The decision makers in the game are either the WBANs/people forming the BBN or the network operators who control the inter-WBAN communicating devices. These devices have to cope with a limited transmission resource (ISM band) that gives rise to a conflict of interests. This thesis aims at exploring the opportunities to enable inter-WBAN communications by ensuring feasible sharing of the radio spectrum through two challenging research issues. First, mutual and cross-technology interference mitigation, and second, the design of a BBN specific routing protocol applied to an epidemic control application within mass gathering areas, such as the airport, as use case in this thesis. In a first phase, a game theoretical approach is proposed to resolve the distributed interference problem in BBNs. The Socially-aware Interference Mitigation (SIM) game performs twofold: at the WBAN stage, it allocates ZigBee channels to body sensors for intra-WBAN data sensing, and at the BBN stage, it allocates WiFi channels to mobile devices for inter-WBAN data transmitting and relaying. Two algorithms, BR-SIM and SORT-SIM, were developed to search for Nash equilibra to the SIM game. The first (BR-SIM) ensures best response solutions while the second (SORT-SIM) attempts to achieve tradeoff between sub-optimal solutions and short convergence time. Then, in order to highlight the social role of BBNs, the second part of this thesis is devoted to propose an epidemic control application tailored to BBNs, in indoor environment. This application implements a geographic routing protocol, that differentiates WBANs traffic and ensures real-time quarantine strategies. (...)

There is an identified problem with patients receiving suboptimal pain management at a hospice agency in the northwestern United States. At this agency, undertreatment of pain is prevalent. Evidence indicates that this may be a result of a lack of guidelines, education, and knowledge of appropriate prescribing. Known barriers to the correct prescription and administration of potent opioids in the hospice setting include prevailing beliefs, knowledge, skills, and attitudes, all of which can impact care negatively. Contextually, hospice principles mandate patient comfort and caregiver involvement in continuous quality improvement, which includes adequate and informed pain management. Moreover, hospice metrics demand requisite knowledge, skills, and attitudes for optimal care, including pain management at the end of life. The Academic Center for Evidence-Based Practice (ACE) star model was used to guide the development of an evidence-based, guideline-supported educational program that will improve pain management at the hospice agency when implemented. The purpose of this project was to use transdisciplinary expertise and team collaboration to develop the program and then to conduct a formative and summative evaluation utilizing experts to prepare the guidelines and process for implementation. Ten experts reviewed the guideline, the educational materials, the process, and the evaluation plan and conducted reviews using the AGREE II tool. The panel of experts agreed within the 6 AGREE domains. Future implementation of this guideline, translation process, and evaluation tool will impact social change through the empowerment of the clinical staff, patients, and caregivers to provide the best pain control and comfort at end of life, a vulnerable time for all patients.

The purpose of this thesis is to find out how a hundred and its public healthcare system managed the 1918 flu pandemic, with Näs hundred as a case study. Relevant information is found using archived copies of the provincial physician's sent letters, editions of the local newspaper, and death-and-funeral books. Such information includes mortality statistics, which measures were taken, which role the private sector had, and if there was any change within the public healthcare system. The study finds that the Spanish flu stood out from other illnesses and the general state of health. At its culmination in October, hundreds were sick and private workplaces were short of staff. The mortality rate seems to have been around 0.49% of the population, which is a reasonable rate in comparison to other case studies. When the epidemic was at its height, the authorities closed schools and prohibited events that attracted larger masses of people. This was announced through the local newspaper, alongside urges for the people to avoid crowding. Within the public healthcare system, there were no extensive changes, except an increase in workdays, a higher salary and a decrease in the number of nurses. There was a discussion on who should be allowed to be cared for in the epidemic hospital, as this hospital, according to routine, did not care for people with influenza or people from outside the central locality. There is no evidence on how this turned out, but some information seems to suggest that the hospital, or at least the epidemic nurse, did get to care for people with influenza. Nonetheless, it is clear that the public healthcare system could not manage the epidemic, and that the majority of people had to be treated in their homes by a relative or an ambulating nurse. When it comes to actions taken by the private sector, charity funding for the victims is the sole provable action. In contrast to other case studies, there is no evidence of private healthcare or charity organizations that would have cooperated with the public healthcare system. This charity, as well as those measures taken by the authorities, can be seen as consequences of a so-called institutional weakening, which itself would be a consequence of the epidemic outbreak. The outbreak showed that the public healthcare system could not handle an epidemic of this size, which in turn made established routines obsolete, showed that there were holes in the system and legitimized interventions made by the authorities. As a consequence, the aforementioned measures were taken to inhibit the spread of the epidemic and to care for the sick. / Syftet med denna uppsats är att undersöka hur ett härad och dess sjukvårdsorganisation klarade av 1918 års influensapandemi, med Näs härad som fallstudie. Relevant information hittades genom att granska provinsialläkarens konceptböcker, nummer av Säffle-Tidningen och död- och begravningsböcker från tiden. Sådan information inkluderar hur sjukan utmärkte sig som bidragande faktor till det allmänna hälsoläget, vilka åtgärder som vidtogs som reaktion av epidemin och ifall någon förändring i sjukvårdens organisation skedde till följd av spanska sjukan. Uppsatsen kommer fram till att spanska sjukan stod ut från övriga sjukdomar och det allmänna hälsoläget. Vid kulmen i oktober var hundratals insjuknade och arbetsplatser hade brist på personal. Dödstalet låg på runt 0,49% av befolkningen, vilket är ett rimligt tal i jämförelse med tidigare forskning. När epidemin var som mest utbredd stängde myndigheterna skolor, biografer och liknande tillställningar som drog till sig större folkmassor. Detta utannonserades i Säffle-Tidningen, samtidigt som de uppmanade folk att hålla distans till sjuka och undvika trängsel. Inom sjukvården kom inga större förändringar, utan främst utökade arbetstider, höjd lön och en minskning i antal sköterskor. En diskussion fanns dock kring vilka som skulle få vårdas i epidemisjukhuset, som enligt rutin inte tog emot folk sjuka av influensa eller folk utanför den centrala köpingen. Det går inte att belägga hur detta kom att se ut, men en del tyder på att epidemisjukhuset, eller åtminstone epidemisjuksköterskan, trotts allt kom att vårda folk sjuka i influensa. Oavsett är det klart att sjukvården inte hade beredskap nog att hantera sjukan, och att majoriteten av de sjuka fick vårdas i hemmet av anhörig eller kringvandrande sjuksköterska. Av vad man kan belägga med det givna källmaterialet är en välgörenhetsfond åt de utsatta det närmsta man kommer vad gäller reaktioner från privat sektor. Till skillnad från fallstudier i tidigare forskning finns inget bevis på att privat vård eller välgörenhetsorganisationer kom att samarbeta med sjukvården. Oavsett kan detta, samt de åtgärder och förändringar som vidtogs av myndigheterna, ses som ha kommit till följd av en institutionell försvagning, som i sig var en följd av det epidemiska utbrottet. Epidemin påvisade nämligen att sjukvården och samhället inte kunde hantera en så stor mängd sjuka, vilket gjorde att rutiner blev obsoleta, att hål i systemet uppenbarades, och interventioner kunde legitimeras av myndigheterna. Som följd vidtogs ovannämnda åtgärder för att försöka hämma epidemins spridning och vårda de sjuka.

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