Depuis une dizaine d'années, une part croissante de fonds de pension rencontrent des difficultés financières. Cette détérioration a soulevé des questions sur la gestion de ces institutions et sur l'efficacité du cadre réglementaires. Cette thèse a pour objet d'analyser les comportements financiers et la gestion des risques opérés par les fonds de pension à prestation définies et les institutions assimilées. En premier lieu, nous relions les choix d'investissement à la question du contrôle managériale. Notre analyse suggère que la bonne gestion des fonds de pension nécessite un partage optimal des droits de contrôle entre les participants du plan et l'entreprise sponsor. Nous montrons alors comment cette répartition affecte les décisions d'investissement. Notre seconde analyse étudie l'impact des fluctuations financières sur la gestion des fonds de pension. Nos résultats suggèrent que le cadre réglementaire actuel conduit à de larges effets pro-cycliques, en particulier sur les exigences de capital et les décisions d'investissement. Finalement, nous analysons comment les changement structurels de la mortalité affectent le risque et les politiques de risque des fonds de pension. / Since ten years, an increasing proportion of pension funds faces to severe financial difficulties, addressing some questions about the management of these institutions and the effectiveness of the regulatory framework. This thesis aims to analyze the investment decisions and financial risk management made by the pension fund defined benefit and assimilated institutions, in order to address some advances for the regulation purpose. First, we address the question of the pension funds management by analyzing the implications of the managerial control problem. Our analysis suggests that the efficient management may require an optimal splitting of control rights between plan participants and the sponsoring company. We then show how this splitting of right controls can affects investment decisions in pension funds. Second, we analyze the implications of financial cycles for pension fund management. Our results suggest that the regulatory framework produces large pro-cyclical, including regime-dependent capital requirement and regime-dependent investment decisions. Finally, we analyze how the structural change in mortality affect the risk and the risk management of pension funds.

La durée de vie humaine augmente dans le monde depuis quelques siècles. Cette augmentation a été plus importante que ne le prédisaient les spécialistes qui ont énoncé des limites. Malgré les incertitudes importantes sur l'avenir de la longévité, la biologie du vieillissement et ses applications semblent en passe de faire chuter les taux de mortalité aux grands âges, similairement à la chute des taux de mortalité infantile il y a 150 ans.L’industrie pharmaceutique prend conscience du potentiel des innovations biomédicales issues de la biologie du vieillissement, rachète des biotechs et développe des équipes en interne. Cela pourrait accélérer l'allongement de la vie.Cependant les tables des actuaires, à l'instar du modèle de type Lee Carter, tendent à prédire une décélération artificielle de la longévité et les risques calculés sont loin de représenter des avancées majeures issues de la biologie du vieillissement.Des modèles de mortalité future sont ici développés sans produire cette décélération. Il apparait qu'une augmentation voisine d'un trimestre par an était jusqu'à présent un meilleur prédicteur que les tendances de chaque pays. D'autres modèles prédisent des accélérations. Nous estimons les impacts sur les retraites.Les efforts pharmaceutiques en cours pour appliquer les résultats de la recherche biomédicale peuvent être craints du fait de leurs impacts sur les retraites. Nous étudions dans quelle mesure un méga fonds de longévité peut à la fois aider à financer les retraites par capitalisation et un grand nombre de développements pharmaceutiques: la mutualisation des risques cliniques permet de capter financièrement des succès biomédicaux liés à la longévité / The human lifespan has been increasing in the world for several centuries. This increase was greater than predicted by specialists who set limits to human age. Despite the significant uncertainties about the future of longevity, the biology of aging and its applications seem about to make old age mortality rates drop, at it happened to infant mortality 150 years ago.The pharmaceutical industry is becoming aware of the potential of biomedical innovations stemming from the biology of aging. It invests in biotechs and develops internal teams. This could accelerate life extension.In parallel, actuarial tables tend to artificially predict longevity decelerations, as for the Lee Carter model, and calculated longevity risks are far from representing major advances from biology of aging.Here, models that do not produce deceleration are developed. It appears that an increase of around one quarter per year was, until now, a better predictor than the trends of each country. Other models predict diverse accelerations, impacts on pensions are analyzed.Current pharmaceutical efforts to apply the results of biomedical research may be feared because of their impact on pensions. Here we study in what measure a longevity megafund can both help finance funded pension schemes and a large number of pharmaceutical developments: the pooling of clinical trial risks can financially capture longevity-related biomedical successes

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Made available in DSpace on 2016-12-08T16:24:22Z (GMT). No. of bitstreams: 1 PGCA15MA174.pdf: 1125115 bytes, checksum: debf2ea0252ff58d406adab80ac46300 (MD5) Previous issue date: 2015-06-25 / Improvement of animal nutrition and management, together with genetic selection for milk yeld, increased the productivity of the herds, especially Holstein cows. On the other hand, characteristics related to fertility, health and longevity were disadvantaged The aim was to compare the development, milk yeld and composition, the health of the mammary gland, the body condition score (BCS), reproductive performance and longevity of crossbred Holstein x Simmental cows with Holstein cows. To obtain the data set two farms were used, one in Bom Retiro in SC and another in Carambeí in PR. For growth evaluation, weight gain of the animals were evaluated monthly. For production and udder health data from the official Dairy Herds Improvement Programs of the farm were used. BCS and body weight estimation were made on the farm with an interval between 60 and 90 days within one year. Information concerning the date of birth, parity date, date and number of inseminations, were obtained from the management software of the farms, generating information regarding the calving interval, days between calving to first service, conception rate, age at first calving. In one of the farms, calving were monitoring to quantify the calving difficulty, in the same farm, information of culling were obtained to determine the survival rate of cows. Data were analyzed by statistical package of SAS, using the MIXED and GENMOD procedures. For growth curve, production and composition of milk, (BCS) and body weight nonlinear regression was used, using the NLIN procedure of SAS and the curves of Gompertz (growth) and Wood (production and composition) were used because of having the lowest mean square. Holstein x Simmental crossbred cows produced more milk 31,8 x 30,4 kg/day (P < 0,05), with higher content of lactose and protein, with no difference for fat content. Holstein cows had higher somatic cell score (SCS) 4.49 x 2.93 (P <0.0001) compared to crossbreed cows. Holstein x Simmental crossbred cows had better BCS during lactation 3.65 x 2.94 (P <0.0001) with no difference in body weight in relation to Holstein cows. For growth of calves and heifers there was no difference between the genetic groups. Crossbred cows Holstein x Simmental had better reproductive performance than the Holstein cows, characterized by lower calving interval (381 x 445 days), higher conception rate (37.31 x 33, 64%) and shorter interval calving to first service (65.6 x 89.3 days). Crossbred cows Holstein x Simmental had higher survival rate than Holstein cows (83 x 92 In conclusion, crossbred cows Holstein x Simmental produce more milk with higher content of lactose and protein, have less ECS and greater BCS without difference for growing of heifers and body weight in adult age. Crossbred cows still have better reproductive performance and have a higher survival rate than the Holstein cows / Melhorias na nutrição e no manejo dos rebanhos bem como a seleção genética para a produção de leite aumentaram a produtividade dos animais. Em contrapartida, características relacionadas a fertilidade, sanidade e longevidade foram prejudicadas. O objetivo foi comparar o desenvolvimento, a produção e composição do leite, a sanidade da glândula mamária, o escore de condição corporal o desempenho reprodutivo e a longevidade de vacas mestiças Holandês x Simental em relação as vacas puras Holandês. Foram utilizadas duas propriedades, uma localizada no município de Bom Retiro em SC e outra em Carambeí no PR. Para avaliação de crescimento o ganho de peso dos animais foi avaliado mensalmente. Para obter dados produtivos e de sanidade de úbere foram utilizados dados do controle leiteiro oficial da propriedade. As avaliações de escore e peso vivo foram realizadas na propriedade com intervalo entre 60 e 90 dias no período de um ano, informações estas obtidas em uma das propriedades. As informações referentes a data de nascimento, data de parto, data e número de coberturas, foram obtidas junto aos software de gerenciamento de ambas as propriedades, gerando informações referentes ao intervalo entre partos (IEP), período parto primeiro serviço, taxa de concepção, idade ao primeiro parto. Em uma das propriedades foi feito o acompanhamento dos partos para quantificar a dificuldade de parto, da mesma forma, foram obtidas informações referentes ao descarte de animais para determinar a taxa de permanência no rebanho das vacas. Os dados foram analisados pelo pacote estatístico SAS, utilizando-se os procedimentos MIXED e GENMOD Para curva de crescimento, de produção e composição do leite bem como escore de condição corporal (ECC) e peso vivo foi utilizada a técnica de regressão não linear, do pacote estatístico SAS sendo que foram utilizadas as curvas de Gompertz (crescimento) e de Wood (produção e composição) por apresentarem o menor quadrado médio do erro. Vacas mestiças Holandês x Simental produziram mais leite 31,8 x 30,4 ( P < 0,05), com maior teor de lactose e proteína, sem diferença para teor de gordura. Vacas Holandês obtiveram maior escore de células somáticas (ECS) 4,49 x 2,93 (P < 0,0001) em relação as mestiças. Vacas mestiças Holandês x Simental obtiveram melhor ECC durante a lactação 3,65 x 2,94 (P < 0,0001) sem diferença para peso vivo em relação as vacas Holandês. Para crescimento de bezerras e novilhas não houve diferença entre os grupamentos genéticos. Vacas mestiças Holandês x Simental obtiveram melhor desempenho reprodutivo em relação as vacas puras, caracterizado através do menor IEP (381 x 445 dias), maior taxa de concepção (37,31 x 33, 64 %) bem como menor intervalo parto primeiro serviço (65,6 x 89,3 dias). Vacas mestiças Holandês x Simental apresentaram maior taxa de permanência no rebanho em relação as vacas puras (83 x 92 %). Conclui-se que vacas mestiças produzem mais leite, com maior teor de lactose e proteína, possuem menos ECS e maior ECC sem diferença para crescimento de novilhas e peso vivo na idade adulta. Apresentam ainda melhor desempenho reprodutivo e maior taxa de permanência no rebanho em relação as vacas puras Holandês

Dans la société contemporaine complexe, surtout depuis de la fin du siècle dernier, s’est développée une inquiétude particulière au sujet de l’acroissement rapide du nombre des personnes âgées et de la longévité de la population. Au Brésil, cet intérêt se manifeste à travers les divers domaines interdisciplinaires d’études scientifiques et par les actions menées dans la sphère du pouvoir public et de la vie privée des personnes, mettant ainsi en évidence la pluralité et la complexité qu’implique le processus de vieillissement. Cette thèse traite de la façon dont la longévité devient une identité collective par excellence dans les municipalités de Maués - Amazonas et Veranopolis - Rio Grande do Sul (Brésil). Compte tenu des effets de la mondialisation dans les villes contemporaines, même celles de moindre importance, qui commencent à chercher de nouvelles vocations - économiques, culturelles - de développement, je considére l'existence d'une «culture de la longévité» construite dans les domaines biologique, social et politique et problématisé dans une perspective anthropologique. Grâce aux méthodes ethnographiques, cette recherche visait à identifier les valeurs que les personnes très agées ou celles s’approchant de ce groupe générationnel, attachent à leur expérience de vie, leurs idées et leurs pratiques et comment ce mode de vie est liée à leur souhait de dépasser l’âge de quatre-vingt ans. Aussi, cette étude recherche à comprendre la construction de la «culture de la longévité» dans la sphère politique en collaboration avec des experts des domaines de la santé qui ont été les précurseurs dans la recherche sur la longévité dans les deux villes. / Na sociedade complexa contemporânea, especialmente a partir da virada do século, tem aumentado a preocupação com o crescimento acelerado do número de idosos e da longevidade da população. No Brasil, o interesse é revelado pelas diversas áreas interdisciplinares de estudo científico, pelas ações na esfera do Estado e no âmbito privado, evidenciando a pluralidade e complexidade que envolve o processo de envelhecimento. Esta tese discute como a longevidade torna-se a identidade coletiva por excelência nos municípios de Maués – Amazonas e Veranópolis – Rio Grande do Sul (Brasil). Considerando os efeitos da globalização nas cidades contemporâneas, mesmo as de pequeno porte, que passam a buscar novas vocações – econômicas, culturais – de desenvolvimento, considero a existência de uma “cultura da longevidade” construída nos âmbitos biológico, social e político e problematizada na perspectiva antropológica. Através do método etnográfico esta pesquisa buscou identificar os valores que os longevos - ou aqueles que se aproximam desse enquadramento - atribuem à sua experiência de vida, às suas práticas e concepções e como esse estilo de vida é relacionado à possibilidade de ultrapassar os oitenta anos. Assim como, compreender a construção da “cultura da longevidade” no âmbito político em conjunto com os especialistas das áreas da saúde que foram os precursores nas investigações sobre a longevidade nos dois municípios. / In complex contemporary society, especially since the turn of the century, has increased the concern about the accelerated growth in the number of elderly and longevity of the population. In Brazil, the interest is revealed by the various interdisciplinary areas of scientific study, the actions in the sphere of the state and the private sphere, showing the diversity and complexity involved in the aging process. This thesis discusses how the longevity becomes the collective identity, for excellence, in the municipalities of Maués – Amazonas and Veranópolis – Rio Grande do Sul (Brazil). Considering the effects of the globalization in the contemporary cities, even the small ones, that go to seek new vocations – economic, cultural – of development, I consider the existence of a “culture of longevity”, constructed in the biological, social and political areas and that is discussed by an anthropological perspective. Through ethnographic method, this research sought to identify the values that the elderlyor those who approach this framework - attach to their life experience, their conceptions and practices and how this lifestyle is related to the possibility of overcoming the eighties. So as, this study intends to understand the construction of the "culture of longevity" in the political sphere in conjunction with experts from the fields of health, which were the forerunners in research on longevity in both cities.

Dans la société contemporaine complexe, surtout depuis de la fin du siècle dernier, s’est développée une inquiétude particulière au sujet de l’acroissement rapide du nombre des personnes âgées et de la longévité de la population. Au Brésil, cet intérêt se manifeste à travers les divers domaines interdisciplinaires d’études scientifiques et par les actions menées dans la sphère du pouvoir public et de la vie privée des personnes, mettant ainsi en évidence la pluralité et la complexité qu’implique le processus de vieillissement. Cette thèse traite de la façon dont la longévité devient une identité collective par excellence dans les municipalités de Maués - Amazonas et Veranopolis - Rio Grande do Sul (Brésil). Compte tenu des effets de la mondialisation dans les villes contemporaines, même celles de moindre importance, qui commencent à chercher de nouvelles vocations - économiques, culturelles - de développement, je considére l'existence d'une «culture de la longévité» construite dans les domaines biologique, social et politique et problématisé dans une perspective anthropologique. Grâce aux méthodes ethnographiques, cette recherche visait à identifier les valeurs que les personnes très agées ou celles s’approchant de ce groupe générationnel, attachent à leur expérience de vie, leurs idées et leurs pratiques et comment ce mode de vie est liée à leur souhait de dépasser l’âge de quatre-vingt ans. Aussi, cette étude recherche à comprendre la construction de la «culture de la longévité» dans la sphère politique en collaboration avec des experts des domaines de la santé qui ont été les précurseurs dans la recherche sur la longévité dans les deux villes. / Na sociedade complexa contemporânea, especialmente a partir da virada do século, tem aumentado a preocupação com o crescimento acelerado do número de idosos e da longevidade da população. No Brasil, o interesse é revelado pelas diversas áreas interdisciplinares de estudo científico, pelas ações na esfera do Estado e no âmbito privado, evidenciando a pluralidade e complexidade que envolve o processo de envelhecimento. Esta tese discute como a longevidade torna-se a identidade coletiva por excelência nos municípios de Maués – Amazonas e Veranópolis – Rio Grande do Sul (Brasil). Considerando os efeitos da globalização nas cidades contemporâneas, mesmo as de pequeno porte, que passam a buscar novas vocações – econômicas, culturais – de desenvolvimento, considero a existência de uma “cultura da longevidade” construída nos âmbitos biológico, social e político e problematizada na perspectiva antropológica. Através do método etnográfico esta pesquisa buscou identificar os valores que os longevos - ou aqueles que se aproximam desse enquadramento - atribuem à sua experiência de vida, às suas práticas e concepções e como esse estilo de vida é relacionado à possibilidade de ultrapassar os oitenta anos. Assim como, compreender a construção da “cultura da longevidade” no âmbito político em conjunto com os especialistas das áreas da saúde que foram os precursores nas investigações sobre a longevidade nos dois municípios. / In complex contemporary society, especially since the turn of the century, has increased the concern about the accelerated growth in the number of elderly and longevity of the population. In Brazil, the interest is revealed by the various interdisciplinary areas of scientific study, the actions in the sphere of the state and the private sphere, showing the diversity and complexity involved in the aging process. This thesis discusses how the longevity becomes the collective identity, for excellence, in the municipalities of Maués – Amazonas and Veranópolis – Rio Grande do Sul (Brazil). Considering the effects of the globalization in the contemporary cities, even the small ones, that go to seek new vocations – economic, cultural – of development, I consider the existence of a “culture of longevity”, constructed in the biological, social and political areas and that is discussed by an anthropological perspective. Through ethnographic method, this research sought to identify the values that the elderlyor those who approach this framework - attach to their life experience, their conceptions and practices and how this lifestyle is related to the possibility of overcoming the eighties. So as, this study intends to understand the construction of the "culture of longevity" in the political sphere in conjunction with experts from the fields of health, which were the forerunners in research on longevity in both cities.

Introdução: No contexto do envelhecimento populacional, uma questão fundamental é avaliar se as estratégias de prevenção de doenças crônicas poderiam contribuir para o aumento dos anos vividos em boas condições de saúde, pela população idosa. Objetivo: Avaliar se a eliminação de determinadas doenças crônicas é capaz de levar à compressão da morbidade em indivíduos idosos. Métodos: Estudo transversal analítico, de base populacional, utilizando dados oficiais secundários para o Município de São Paulo, em 2000, e dados obtidos a partir do estudo SABE. O método de Sullivan foi utilizado para o cálculo de expectativas de vida livre de incapacidade (E.V.L.I.). O impacto da eliminação de uma doença na prevalência de incapacidade foi estimado com um modelo de regressão logística múltipla. Tábuas de vida de eliminação de causas foram utilizadas para calcular as probabilidades de morte com a eliminação de doenças. O efeito da eliminação das doenças crônicas foi avaliado, considerando a teoria de riscos competitivos e a abordagem proposta por Nusselder e colaboradores. Resultados: Os maiores ganhos em E.V.L.I., com a eliminação de doenças crônicas, ocorreram no sexo feminino, levando a um processo de compressão absoluta da morbidade. Nos indivíduos de idade mais avançada, os ganhos em E.V.L.I., ocorreram em função de um processo de compressão relativa da morbidade. Nos homens com idade de 75 anos, todas as doenças estudadas, com exceção da doença cardíaca e da hipertensão arterial sistêmica, levaram a um processo de expansão absoluta da morbidade, mas simultaneamente a um processo de compressão relativa da morbidade, ao serem eliminadas. A doença cardíaca apresentou-se como aquela que mais promoveria a compressão da morbidade, caso fosse eliminada, em ambos os sexos. Conclusão: A eliminação de doenças crônicas na população idosa poderia levar a uma compressão da morbidade em homens e mulheres, tanto na idade de 60 anos, quanto na de 75 anos / Introduction: In the context of the aging process, a key issue is to assess whether strategies to prevent chronic diseases may contribute to the increase in years lived in good health among elderly individuals. Objective: To evaluate whether elimination of certain chronic diseases can lead to the compression of morbidity, in the elderly. Methods: Analytical cross-sectional survey, based on official data for the city of São Paulo, in 2000, and data obtained from the SABE study. Sullivans method was used for the calculation of disability-free life expectancy (DFLE). Cause-deleted disability prevalence was estimated using multiple logistic regression model. Cause-deleted probabilities of dying were derived with the cause-elimination life-table technique, considering the independence of the causes of based on the approach proposed by Nusselder and co-workers. Results: The greatest gains in DFLE, with the elimination of chronic diseases, occurred in women, leading to a process of absolute compression of morbidity. Among individuals of a more advanced age, gains in DFLE occurred due to a relative compression of morbidity process. Among men aged 75 years, all diseases eliminated, except heart disease and hypertension, led to a process of absolute expansion of morbidity, but simultaneously, to a relative compression of morbidity. If eliminated, heart disease was the condition that would most lead to the compression of morbidity in both genders. Conclusion: The elimination of chronic diseases in the elderly population could lead to the compression of morbidity in men and women at both 60 years of age and in 75 years of age or older

Depuis longtemps les modèles de type phase sont utilisés dans plusieurs domaines scientifiques pour décrire des systèmes qui peuvent être caractérisés par différents états. Les modèles sont bien connus en théorie des files d’attentes, en économie et en assurance.<p><p>La thèse est focalisée sur différentes applications des modèles de type phase en assurance et montre leurs avantages. En particulier, le modèle de Lin et Liu en 2007 est intéressant, parce qu’il décrit le processus de vieillissement de l’organisme humain. La durée de vie d’un individu suit une loi de type phase et les états de ce modèle représentent des états de santé. Le fait que le modèle prévoit la connexion entre les états de santé et l’âge de l’individu le rend très utile en assurance.<p><p>Les résultats principaux de la thèse sont des nouveaux modèles et méthodes en assurance pension et en assurance santé qui utilisent l’hypothèse de la loi de type phase pour décrire la durée de vie d’un individu.<p><p>En assurance pension le but d’estimer la profitabilité d’un fonds de pension. Pour cette raison, on construit un modèle « profit-test » qui demande la modélisation de plusieurs caractéristiques. On décrit l’évolution des participants du fonds en adaptant le modèle du vieillissement aux causes multiples de sortie. L’estimation des profits futurs exige qu’on détermine les valeurs des cotisations pour chaque état de santé, ainsi que l’ancienneté et l’état de santé initial pour chaque participant. Cela nous permet d’obtenir la distribution de profits futurs et de développer des méthodes pour estimer les risques de longevité et de changements de marché. De plus, on suppose que la diminution des taux de mortalité pour les pensionnés influence les profits futurs plus que pour les participants actifs. C’est pourquoi, pour évaluer l’impact de changement de santé sur la profitabilité, on modélise séparément les profits venant des pensionnés.<p><p>En assurance santé, on utilise le modèle de type phase pour calculer la distribution de la valeur actualisée des coûts futurs de santé. On développe des algorithmes récursifs qui permettent d’évaluer la distribution au cours d’une période courte, en utilisant des modèles fluides en temps continu, et pendant toute la durée de vie de l’individu, en construisant des modèles en temps discret. Les trois modèles en temps discret correspondent à des hypothèses différentes qu’on fait pour les coûts: dans le premier modèle on suppose que les coûts de santé sont indépendants et identiquement distribués et ne dépendent pas du vieillissement de l’individu; dans les deux autres modèles on suppose que les coûts dépendent de son état de santé.<p> / Doctorat en Sciences / info:eu-repo/semantics/nonPublished

Patagonian toothfish (Dissostichus eleginoides) or "Chilean sea bass" support a valuable and controversial fishery, but the life history is little known and longevity estimates range from ~20 to more than 40 or 50 yr. In this study, lead-radium dating provided validated age estimates from juveniles to older adults, supporting the use of otoliths as accurate indicators of age. The oldest age groups were near 30 yr, which provided support for age estimates exceeding 40 or 50 yr from grow zone counts in otolith sections. Hence, scale reading, which rarely exceeds 20 years, has the potential for age underestimation. Lead-radium dating revealed what may be minor differences in age interpretation between two facilities and findings may provide an age-validated opportunity for the CCAMLR Otolith Network to reassess otolith interpretations. Orange roughy (Hoplostethus atlanticus) support a major deep-sea fishery and stock assessments often depend on age analyses, but lifespan estimates range from ~20 to over 100 yr and validation of growth zone counts remained unresolved. An early application of lead-radium dating supported centenarian ages, but the findings were met with disbelief and some studies have attempted to discredit the technique and the long lifespan. In this study, an improved lead-radium dating technique used smaller samples than previously possible and circumvented assumptions that were previously necessary. Lead-radium dating of otolith cores, the first few years of growth, provided ratios that correlated well with the ingrowth curve. This provided robust support for age estimates from otolith thin sections. Use of radiometric ages as independent age estimates indicated the fish in the oldest group were at least 93 yr. Lead-radium dating has validated a centenarian lifespan for orange roughy. To date, radium-226 has been measured in otoliths of 39 fish species ranging from the northern Pacific and Atlantic Oceans to the Southern Ocean. In total, 367 reliable radium-226 measurements were made in 36 studies since the first lead-radium dating study on fish in 1982. The activity of radium-226 measurements ranged over 3 orders of magnitude (<0.001 to >1.0 dpm.g⁻¹). An analysis revealed ontogenetic differences in radium-226 uptake that may be attributed to changes in habitat or diet. Radiometric age from otolith core studies was used to describe a radium-226 uptake time-series for some species, which revealed interesting patterns over long periods. This synopsis provides information on the uptake of radium-226 to otoliths from an environmental perspective, which can be used as a basis for future studies.

Sensor nodes in a wireless sensor network (WSN) have a small, non-rechargeable power supply. Each message transmission or reception depletes a sensor node’s energy. Many WSN applications are ad-hoc deployments where a sensor node is only aware of its immediate neighbours. The lack of a predefined route path and the need to restrict the amount of communication that occurs within the application area impose constraints on WSNs not prevalent in other types of networks. An area of active research has been how to notify the central sink (or monitoring hub) about an event in real-time by utilising the minimum number of messages to route a message from a source node to the destination sink node. In this thesis, strategies to limit communication within a WSN application area, while ensuring that events are reported on and responded to in real-time, is presented. A solution based on modelling a WSN as a small world network and then transmitting an initialisation message (IM) on network start-up to create multiple route paths from any sensor node to one or more sinks is proposed. The reason for modelling a WSN as a small world network is to reduce the number of nodes required to re-transmit a message from a source sensor node to a sink. The purpose of sending an IM at network start-up is to ensure that communication within the WSN is minimised. When routing a message to a static sink, the nodes closest to the static sink receive a disproportionate number of messages, resulting in their energy being consumed earlier. The use of mobile sinks has been proposed but to our knowledge no studies have been undertaken on the paths these mobile sinks should follow. An algorithm to determine the optimum path for mobile sinks to follow in a WSN application area is described. The purpose of an optimum path is to allow more equitable usage of all nodes to transfer an event message to a mobile sink. The idea of using multiple static sinks placed at specific points in the small world model is broadened to include using multiple mobile sinks called actors to move within a WSN application area and respond to an event in real-time. Current coordination solutions to determine which actor(s) must respond to the event result in excessive message communication and limit the real-time response to an event. An info gap decision theory (IGDT) model to coordinate which actor or set of actors should respond to the event is described. A comparison of the small world routing (SWR) model against routing using flooding and gossiping shows that the SWR model significantly reduces the number of messages transmitted within the network. An analysis of the number of IMs transmitted and received at individual node level shows that prudent selection of the hop count (number of additional nodes required to route a message to sink) to a sink node will result in a reduced number of messages transmitted and received per node within the network. The use of the IGDT model results in a robust decision on the actor(s) chosen to respond to an event even when uncertainty about the location and available energy of other actor(s) exists. / Thesis (PhD(Eng))--University of Pretoria, 2012. / Electrical, Electronic and Computer Engineering / unrestricted