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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Stressrelaterad ohälsa och utmattningssyndrom i en storstadsregion : En tvärsnittsstudie / Stress Related Illness and Exhaustion Syndrome in a Conurbation : A Cross-sectional Study

Hjalmarsson, Lina, Högström, Kristina January 2013 (has links)
Bakgrund: Stressrelaterad ohälsa och utmattningssyndrom ökar i Sverige vilket leder till fler långtidssjukskrivningar. Detta innebär ett stort lidande för de drabbade och höga kostnader för samhället. Stress som kvarstår under längre tid påverkar kroppen negativt och leder till kognitiv utmattning, sömnproblematik, utbredd trötthet, somatiska besvär, irritabilitet och negativ affekt. Utsatta personer är även i riskgrupper för allvarliga somatiska sjukdomar. Syfte: Att beskriva förekomsten av stressrelaterad ohälsa och utmattningssyndrom i en storstads-region. Metod: Data samlades in genom ett tvärsnittsurval bland kvinnor och män i arbetsför ålder boende i en storstadsregion. Mätinstrumentet som användes var Karolinska Exhaustion Scale (KES) (26). Korrelationsanalyser gjordes för att sedan jämföras med en tidigare studie där patienter diagnostiserade med utmattningssyndrom ingick i urvalet. Resultat: Respondenterna uppgav att symtom på fatigue och sömnsvårigheter var mest utbredda följt av irritabilitet. Ingen signifikant skillnad påvisades mellan kvinnor och män, ensam- eller sammanboende i urvalsgruppen. Studien påvisar en statistisk signifikant skillnad mellan studiens urvalsgrupp och en patientgrupp från en tidigare studie. Detta indikerar sämre stressrelaterad hälsa bland patientgruppen. Slutsats: Studiens resultat visar fatigue och sömnsvårigheter var mest förekommande av symtomen på stressrelaterad ohälsa i urvalsgruppen. Någon slutsats om skillnader mellan kön, ensamboende och sammanboende inom urvalsgruppen har inte kunnat konstateras. Stor signifikant skillnad kunde påvisas mellan urvalsgruppen och patientgruppen från en tidigare studie. Klinisk betydelse: Sammanställd data från studien kommer att användas för vidare forskning. / Background: Stress related illness and burnout are increasing which contributes to further long term sick leaves in Sweden. This causes great suffer for the individual and high expenses to the society. Being a subject to long term stress will have a negative impact on the body and may lead to cognitive exhaustion, disturbed sleep, excessive fatigue, somatic symptoms, irritability and negative affectivity. Exposed people are also at risk for other severe somatic illness. Aim: To describe the presence of stress related illness and burnout in a conurbation. Method: Data was gathered from cross-sectional samples consisting of women and men in a working age living in a conurbation. The study’s instrument was the Karolinska Exhaustion Scale (KES) (26). Correlation analyses were employed to compare with a sample from a previous study with patients diagnosed with burnout. Result: The findings show that individuals in the study had most difficulties with symptoms referring to fatigue and disturbed sleep, followed by irritability. No conclusion was made referring to differences between men and women or between those living alone and the cohabitants as no significant difference could be proven. There was a significant difference between the sample of the study and the sample from patients of the previous study. Conclusion: The findings of the study shows that of all the symptoms of stress related illness fatigue and disturbed sleep had the highest prevalence among the sample. Conclusions referring to differences between gender, individuals living alone and the cohabitants could not be proven. High significance level was found when comparing the sample of the study with a sample from a previous study with patients diagnosed with burnout. Clinical implication: Gathered data from the study will be used for further research. / <p>Röda Korsets sjuksköterskeförening stipendium 2014</p>
2

Adaptation, population viability and colonization-extinction dynamics of <em>Silene tatarica</em> in riparian habitats

Jäkäläniemi, A. (Anne) 06 September 2005 (has links)
Abstract Plants in riparian environments have to tolerate disturbances like floods and erosion. In the absence of disturbances, habitats will gradually become unfavorable for early-successional species. This can have fundamental consequences not only for adaptation at the individual level, but also for the viability of local populations as well as for the persistence of the species on a regional scale. Silene tatarica is a rare perennial plant exposed to annual floods of the Oulanka River. After sand burial most plants formed vertical rhizomes and new meristems by bud ramification. The special anatomical features of these fleshy underground structures seemed to allow the plants to be very resilient against fast-flowing water. Seed structure may enhance long-distance dispersal by water. Selection gradients for plant height were positive at the individual and group levels, but for the number of stems they were in opposition, as selection at the group level favored a smaller number of stems. This can be associated with pollination and herbivory, since taller and larger plants often attract more pollinators and mammalian herbivores. At the local level, population growth was most sensitive to the survival and growth of juvenile individuals. The populations showed different fates, and according to stochastic simulations some of them will disappear in the near future. Their colonization and extinction rates varied between the years, but their balance over the study period was positive. Small patches had the highest risk of extinction and recolonization of extinct patches was very rare. Elasticity analysis indicated that the survival of patches made a much greater contribution to patch dynamics than did the production of new patches. The short-term dynamics of S. tatarica depend primarily on local dynamics but, in the long run, the species will track the availability of habitat, and its persistence will depend on successful colonizations. The amount of suitable habitat depends on river disturbance. Conservation of this species requires the creation of new suitable open sites for colonization, a dispersal process leading to successful colonizations, and favorable habitats for survival. These conditions can be maintained either by natural processes of river disturbance or by active conservation management.
3

Rapid divergence of local populations with different color forms in the dung beetle Phelotrupes auratus revealed by population genomics analyses / 集団ゲノム解析で明らかになった食糞性甲虫オオセンチコガネにおける異なる色彩型の地域集団の急速な分化

Araki, Yoshifumi 23 January 2023 (has links)
京都大学 / 新制・課程博士 / 博士(理学) / 甲第24310号 / 理博第4880号 / 新制||理||1698(附属図書館) / 京都大学大学院理学研究科生物科学専攻 / (主査)教授 曽田 貞滋, 准教授 渡辺 勝敏, 教授 中務 真人 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM
4

Effekter av land grabbing i Etiopien : En litteraturstudie med fokus på lokalbefolkningens försörjning och miljön / Effects of land grabbing in Ethiopia : A literature study with a focus on the local population's livelihood and the environment

Basha, Basha, Sadiqi, Amin January 2023 (has links)
Efter finanskrisen 2007–2008 blev jordbruksmark attraktiv som en investeringsmöjlighet, vilket innebar att många utländska företag, stater eller privata investerare förvärvade storskaliga områden av odlingsbar mark. Detta fenomen, som kallas för land grabbing, är särskilt förekommande i utvecklingsländer och det globala syd. Trots påståenden om att sådana investeringar kan bidra till utveckling och möjligheter i fattiga länder, visar forskning att det i själva verket har motsatt effekt. Syftet med detta arbete är att genomföra en litteraturstudie för att undersöka konsekvenser av land grabbing i Etiopien. En kvalitativ forskningsstrategi som består av litteraturstudie har använts. Med hjälp av aspekter inom teorier om försörjning såsom naturkapital, fysiskt kapital, mänskligt kapital, finansiellt kapital och socialt kapital samt tematisk analys har litteraturen analyserats. Resultatet visar att storskaliga land grabbing i Etiopien har en direkt påverkan på den lokala befolkningens försörjningsmöjligheter som undermineras genom förluster av mark samt tillgång till mark och viktiga naturresurser. Studien visar även att de utländska markinvesteringarnas hantering och produktion av bland annat kaffe, biobränsle, gruvdrift vidare har en negativ påverkan på miljön, biologisk mångfald och det lokala ekosystemet. Detta har resulterat i en matosäkerhet och socioekonomisk utsatthet bland befolkningen. Studien visar också att lokalbefolkningen inte inkluderas i beslutsfattande som rör deras mark och att de oftast inte får tillräcklig kompensation/ersättning för förlust av mark eller andra tillgångar, vilket tyder på brott mot mänskliga rättigheter. / After the financial crisis of 2007–2008, agricultural land became an attractive investment opportunity, which meant that many foreign companies, states, or private investors acquired large-scale land areas. This phenomenon, called land grabbing, is particularly prevalent in developing countries and the global south. Despite claims that such investment can contribute to development and opportunity in poorer countries, research shows it has the opposite effect. The purpose of this work is to conduct a literature study to investigate the consequences of land grabbing in Ethiopia. A qualitative research strategy consisting of a literature study has been used. The data was analyzed by using aspects of the livelihood approach such as natural capital, physical capital, human capital, financial capital, and social capital as well as a thematic analysis. The results show that large-scale land grabbing in Ethiopia has a direct impact on the livelihood of the local population, which is undermined through losses of land and access to land and important natural resources. The study also shows that the foreign land investments' management and production of, among other things, coffee, biofuel, and mining also harm the environment, biological diversity, and the local ecosystem. This has resulted in food insecurity and socioeconomic vulnerability among the population. Furthermore, the study also shows that local people are not included in decision-making concerning their land and they often do not receive sufficient compensation for the loss of land or other assets, which indicates violations of human rights.
5

Usos e percep??es de comunidades do entorno de uma unidade de conserva??o do semi?rido nordestino: instrumentos para gest?o?

Silva, Thaise Sousa da 27 February 2009 (has links)
Made available in DSpace on 2014-12-17T15:54:52Z (GMT). No. of bitstreams: 1 ThaiseSS.pdf: 718076 bytes, checksum: 64a98bfc820098a42e87b1c389114353 (MD5) Previous issue date: 2009-02-27 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / The loss of Earth?s biodiversity is a major concern for the international scientific community and megadiverse countries like Brazil are paramount for discussions about the overall situation of the planet. The Caatinga biome is probably one of the most threatened in Brazil and the implementation of Conservation Units (CU) represents a measure for protecting its natural resources and biodiversity. The Station Ecological of Serid? (ESEC-Serido) is one of the few CU in the Caatinga of Rio Grande do Norte State (NE Brazil) and interacts with several neighboring communities and settlements. However the ESEC does not integrate environmental perception feedback from the local communities in its management plan. Considering this, the present articles aims at identifying the perceptions and concepts of such communities regarding environmental issues and biodiversity as well as indicate strategies to improve the administration of this CU. In order to achieve these goals, a review of the specialized literature was carried out and a research tool based on Environmental Perception was developed in the form of structured interviews applied to the persons from communities neighboring the ESEC. These interviews were later processed through content analysis. The concepts and perceptions obtained through this analysis show that the people from the environs are aware of the main problems faced by ESEC-Serid?, as well as the strategies to address them / A situa??o do planeta envolve discuss?es sobre perdas da biodiversidade. Pa?ses como o Brasil, um dos maiores em biodiversidade, n?o poderia escapar ? essas discuss?es. Um de seus Biomas, e provavelmente o mais amea?ado ? a Caatinga. Uma das a??es que visa a prote??o de ?reas naturais e da biodiversidade ? a manuten??o de Unidades de Conserva??o (UC s). Uma dessas UC s da Caatinga ? a Esta??o Ecol?gica do Serid? (ESEC Serid?) que, apesar de ter em seu entorno v?rias comunidades que interagem com ela, n?o inclui a percep??o dessas popula??es em sua forma de gest?o. Neste sentido, o objetivo do artigo ? identificar as percep??es e conceitos dessas comunidades sobre a ESEC Serid?, assim como, as estrat?gias devem ser adotadas para sua melhor forma de atua??o. Para alcan?ar esses objetivos dessa pesquisa realizou-se pesquisa bibliogr?fica, elabora??o de um instrumento baseado nas pr?ticas da Percep??o Ambiental, na forma de entrevista estruturada aplicada ? popula??o do entorno dessa ESEC, e os dados tratados atrav?s da an?lise de conte?do. Os resultados mostram de forma clara nos discursos da popula??o, seus conceitos e percep??es, os principais problemas enfrentados pela ESEC Serid?, bem como estrat?gias para a resolu??o dos mesmos, sendo observado no conhecimento das pessoas a realidade enfrentada pela ESEC e sua poss?vel melhoria como ?rea de prote??o da natureza
6

Participation et tourisme : quelle place pour la population ? Une étude exploratoire d'initiatives participatives au Brésil. / Participation and tourism : what place for population? An exploratory study of participatory initiatives in Brazil.

Seno Alves, Daiane 26 June 2018 (has links)
Les débats autour du « durable » retournent le regard du développement vers le local. La participation citoyenne commence ainsi à intégrer les projets de développement territorial en tant qu’outil pour faire rapprocher les habitants aux décisions et aux décideurs de projets, en même temps qu’ils se réapproprient leur territoire. Les publications apparues autour de la participation jusqu’à présent se dédient notamment à sa définition et moyens. Certaines se positionnent dans un contexte précis et nous donnent des idées plus concrètes du terrain. Cependant, la plupart de recherches sur la participation et la concertation analysent soit des cas liés à la gestion de ressources naturelles (gestion de l’eau ou des forêts...), soit de l’aménagement urbain. Il existe pourtant une activité qui est encore peu étudiée et qui touche l’ensemble des caractéristiques du territoire : le tourisme. Peu d’ouvrages (notamment sur le tourisme solidaire ou responsable) sont dédiés à analyser l’importance du développement participatif dans le domaine. Nous souhaitons étudier ce type de développement dans le tourisme de manière globale afin de comprendre les relations complexes entre la population, les décideurs, les autres acteurs, le projet, le territoire et les touristes. Même si nous nous inspirons des cas de développement participatif dans d’autres domaines, il restera toujours une marge de différence assez significative entre eux et le tourisme. C’est pourquoi nous croyons que des analyses plus précises d’un développement participatif dans le tourisme doivent être menées en parallèle. Ces analyses cherchent comprendre tout d’abord dans quelles mesures ce type de développement est important pour l’évolution durable du tourisme pour ensuite déterminer les niveaux de participation plus pertinents et comment les mettre en oeuvre. Ce travail a un caractère exploratoire et cherche développer une compréhension théorique du(des) rôle(s) de la participation citoyenne aux décisions et projets touristiques. Même si cette recherche devrait être considérée plus exploratoire que comparative, nous avons autant l’ambition de tracer quelques comparaisons vers la fin. La motivation première de cette étude concerne la nécessité d’impliquer les habitants dans les politiques et projets touristiques locaux. Ainsi, la question globale de la recherche a été identifiée : la participation de la population peut-elle représenter un facteur de durabilité pour le développement d’un tourisme plus inscrit dans le territoire ? À partir de là, d’autres questionnements sont faits : Quelle est la réalité de la participation citoyenne dans les décisions touristiques ? Les avis de la population sont-ils pris en compte par les autorités responsables ? Comment cette implication peut-elle influencer à la fois le tourisme installé sur le territoire (images, valorisation, accueil, flux...) et la vie quotidienne des habitants (qualité, sentiments, aménités, relations...) ? / Debates around “sustainability” focus the development on the local level. Citizen participation becomes therefore part of territorial development projects as a tool that at the same time brings closer inhabitants and projects decision-makers and allows the first ones to reappropriate their territory. Publications about participation so far worry about its definition and the necessary means. Some talk about more precised contexts and give us real concrete ideas. Nevertheless, research about participation and dialogue analyzes either cases of natural resources management (e.g. water or forests management) or city planning. There is however a less studied activity which touches all the characteristics of a territory: tourism. Few texts (mainly about solidarity or responsible tourism) are dedicated to the analysis of the importance of participatory development in the sector. We propose a general study of this kind of development in tourism in order to understand complex relations between population, decision-makers, other actors, projects, territory and tourists. Even if we get inspired by cases of participatory development in other fields, there will always be a large margin of difference between them and tourism. That is why we believe that more specific analyses of participatory development in tourism must be drawn in parallel. These analyses try firstly to understand in which ways this kind of development is important to a sustainable evolution of tourism. In this way, later on the study it is possible to determine the pertinent levels of participation and how to employ them. This work has an explorative character and seeks to develop a theoretical understanding of citizen participation role(s) in touristic decision-making and projects. Even though the study should be considered as explorative rather than comparative, our ambition is to make some comparative notes by the end of it. The initial research problem motivating this study concerns the need of involvement of inhabitants in local touristic politics and projects. Hence, one overall research question has been defined: Can people’s participation represent a factor of sustainability to the development of a tourism fitting well in a territory? From that reflection, other questions are made: What is the reality of citizen participation in touristic decision-making? Are people’s opinions taken into consideration by the responsible authorities? How can this involvement influence at the same time the tourism on a territory (images, promotion, welcome, flows, etc.) and the everyday life of inhabitants (quality, feelings, amenities, relations, etc.)?
7

Mathematical modeling of an epidemic under vaccination in two interacting populations

Ahmed, Ibrahim H.I. January 2011 (has links)
<p><b>In this dissertation we present the quantitative response of an epidemic of the so-called SIR-type, in a population consisting of a local component and a migrant component. Each component can be divided into three classes, the susceptible individuals, usually denoted by S, who are uninfected but may contract the disease, infected individuals (I) who are infected and can spread the disease to the susceptible individuals and the class (R) of recovered individuals. If a susceptible individual becomes infected, it moves into the infected class. An infected individual, at recovery, moves to the class R. Firstly we develop a model describing two interacting populations with vaccination. Assuming the vaccination rate in both groups or components are constant, we calculate a threshold parameter and we call it a vaccination reproductive number. This invariant determines whether the disease will die out or becomes endemic on the (in particular, local) population. Then we present the stability analysis of equilibrium points and the effect of vaccination. Our primary finding is that the behaviour of the disease free equilibrium depend on the vaccination rates of the combined population. We show that the disease free equilibrium is locally asymptotically stable if the vaccination reproductive number is less than one. Also our stability analysis show that the global stability of the disease free equilibrium depends on the basic reproduction number, not the vaccination reproductive number. If the vaccination reproductive number is greater than one, then the disease free equilibrium is unstable and there exists three endemic equilibrium points in our model. Two of these three endemic equilibria are so-called boundary equilibrium points, which means that the infection is only in one group of the population. The third one which we focus on is the general endemic point for the whole system. We derive a threshold condition that determines whether the endemic equilibria is locally asymptotically stable or not. Secondly, by assuming that the rate of vaccination in the migrant population is constant, we apply optimal control theory to find an optimal vaccination strategy in the local population. Our numerical simulation shows the effectiveness of the control strategy. This model is suitable for modeling the real life situation to control many communicable diseases. Models similar to the model used in the main contribution of our dissertation do exist in the literature. In fact, our model can be regarded as being in-between those of [Jia et al., Theoretical Population Biology 73 (2008) 437-448] and [Piccolo and Billings, Mathematical and Computer Modeling 42 (2005) 291-299]. Nevertheless our stability analysis is original, and furthermore we perform an optimal control study whereas the two cited papers do not. The essence of chapter 5 and 6 of this dissertation is being prepared for publication.</b></p>
8

Enforcing Legitimacy : Perspectives on the Relationship between Intervening Armed Forces and the Local Population in Afghanistan

Karlborg, Lisa January 2015 (has links)
Bolstering local perceptions of legitimacy in armed intervention has emerged as an important feature of increasingly complex international peace and statebuilding efforts. Yet, previous research has only begun to explore what local legitimacy entails to those involved in, and affected by, armed intervention. This dissertation advances an understanding of local legitimacy as a perception-based, relational phenomenon. Through this lens, it examines armed intervention in Afghanistan (2001-2014). In particular, this dissertation studies how the relationship between Afghan citizens and intervening armed forces interacts with, and shapes, perspectives on local legitimacy held by the main 'interveners' and those 'intervened upon'. This dissertation consists of an introduction, which situates the study in a wider context, and four essays. Beginning with the organizational perspectives of the main intervening actors in Afghanistan, Essay I finds that the UN and NATO initially conceptualized problems of local legitimacy as principally the consequence of a fragile Afghan state, and not as failings of the intervention. When negative dimensions of intervention became increasingly recognized, principal responsibility for the legitimacy process shifted away from intervening authorities and onto the Afghan state. Similarly, Essay II shows how key U.S. military doctrine, over time, reconceptualized the formal duty of intervening forces in the local legitimacy process, ultimately considering it contingent on, and subordinate to, the will and capabilities of host-state authorities and the local population. Turning thereafter to firsthand accounts from the field, Essay III and Essay IV together contrast personal perspectives on the intervention held by U.S. Army Officers and Afghan citizens. Essay III finds that personal experiences of noncombat contact with Afghans reinforced the Officers' sense of duty toward the local population. Conversely, Essay IV suggests that the local legitimacy of intervening forces became increasingly contested among Afghans, due largely to the perceived intensification of foreign intrusion on 'everyday' life. Taken together, the findings of this dissertation lay the foundation for the development of a new concept, the host-citizen contract. In so doing, it provides a social contract framework to better understand the complex dynamics of local legitimacy in Afghanistan, and beyond.
9

Mathematical modeling of an epidemic under vaccination in two interacting populations

Ahmed, Ibrahim H.I. January 2011 (has links)
<p><b>In this dissertation we present the quantitative response of an epidemic of the so-called SIR-type, in a population consisting of a local component and a migrant component. Each component can be divided into three classes, the susceptible individuals, usually denoted by S, who are uninfected but may contract the disease, infected individuals (I) who are infected and can spread the disease to the susceptible individuals and the class (R) of recovered individuals. If a susceptible individual becomes infected, it moves into the infected class. An infected individual, at recovery, moves to the class R. Firstly we develop a model describing two interacting populations with vaccination. Assuming the vaccination rate in both groups or components are constant, we calculate a threshold parameter and we call it a vaccination reproductive number. This invariant determines whether the disease will die out or becomes endemic on the (in particular, local) population. Then we present the stability analysis of equilibrium points and the effect of vaccination. Our primary finding is that the behaviour of the disease free equilibrium depend on the vaccination rates of the combined population. We show that the disease free equilibrium is locally asymptotically stable if the vaccination reproductive number is less than one. Also our stability analysis show that the global stability of the disease free equilibrium depends on the basic reproduction number, not the vaccination reproductive number. If the vaccination reproductive number is greater than one, then the disease free equilibrium is unstable and there exists three endemic equilibrium points in our model. Two of these three endemic equilibria are so-called boundary equilibrium points, which means that the infection is only in one group of the population. The third one which we focus on is the general endemic point for the whole system. We derive a threshold condition that determines whether the endemic equilibria is locally asymptotically stable or not. Secondly, by assuming that the rate of vaccination in the migrant population is constant, we apply optimal control theory to find an optimal vaccination strategy in the local population. Our numerical simulation shows the effectiveness of the control strategy. This model is suitable for modeling the real life situation to control many communicable diseases. Models similar to the model used in the main contribution of our dissertation do exist in the literature. In fact, our model can be regarded as being in-between those of [Jia et al., Theoretical Population Biology 73 (2008) 437-448] and [Piccolo and Billings, Mathematical and Computer Modeling 42 (2005) 291-299]. Nevertheless our stability analysis is original, and furthermore we perform an optimal control study whereas the two cited papers do not. The essence of chapter 5 and 6 of this dissertation is being prepared for publication.</b></p>
10

Mathematical modeling of an epidemic under vaccination in two interacting populations

Ahmed, Ibrahim H.I. January 2011 (has links)
>Magister Scientiae - MSc / In this dissertation we present the quantitative response of an epidemic of the so-called SIR-type, in a population consisting of a local component and a migrant component. Each component can be divided into three classes, the susceptible individuals, usually denoted by S, who are uninfected but may contract the disease, infected individuals (I) who are infected and can spread the disease to the susceptible individuals and the class (R) of recovered individuals. If a susceptible individual becomes infected, it moves into the infected class. An infected individual, at recovery, moves to the class R. Firstly we develop a model describing two interacting populations with vaccination. Assuming the vaccination rate in both groups or components are constant, we calculate a threshold parameter and we call it a vaccination reproductive number. This invariant determines whether the disease will die out or becomes endemic on the (in particular, local) population. Then we present the stability analysis of equilibrium points and the effect of vaccination. Our primary finding is that the behaviour of the disease free equilibrium depend on the vaccination rates of the combined population. We show that the disease free equilibrium is locally asymptotically stable if the vaccination reproductive number is less than one. Also our stability analysis show that the global stability of the disease free equilibrium depends on the basic reproduction number, not the vaccination reproductive number. If the vaccination reproductive number is greater than one, then the disease free equilibrium is unstable and there exists three endemic equilibrium points in our model. Two of these three endemic equilibria are so-called boundary equilibrium points, which means that the infection is only in one group of the population. The third one which we focus on is the general endemic point for the whole system. We derive a threshold condition that determines whether the endemic equilibria is locally asymptotically stable or not. Secondly, by assuming that the rate of vaccination in the migrant population is constant, we apply optimal control theory to find an optimal vaccination strategy in the local population. Our numerical simulation shows the effectiveness of the control strategy. This model is suitable for modeling the real life situation to control many communicable diseases. Models similar to the model used in the main contribution of our dissertation do exist in the literature. In fact, our model can be regarded as being in-between those of [Jia et al., Theoretical Population Biology 73 (2008) 437-448] and [Piccolo and Billings, Mathematical and Computer Modeling 42 (2005) 291-299]. Nevertheless our stability analysis is original, and furthermore we perform an optimal control study whereas the two cited papers do not. The essence of chapter 5 and 6 of this dissertation is being prepared for publication. / South Africa

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