Le Morvan et les Cévennes sont des massifs protégés pour leur paysage et leur biodiversité exceptionnels. Cependant dès la Protohistoire, ces régions réputées pour la qualité de leur environnement ont été le lieu d’activités minières et métallurgiques. Les effets de telles activités peuvent être rémanents sur les écosystèmes, il est donc important dans un premier temps de les localiser, puis de quantifier leur impact sur la faune et la flore. Le présent travail propose une démarche pluridisciplinaire alliant archéologie, géochimie, écologie et écotoxicologie. L’application de méthodes statistiques empruntées à la prospection minière a permis de dresser des cartes de potentiel minier, supposées guider l’archéologue dans ses recherches de terrain. Des cartes de distribution spatiale des éléments traces métalliques ont été construites sur six sites (trois dans chaque parc). La biodisponibilité des éléments traces métalliques a été estimée sur des mulots, des truites et des bryophytes. Bien que la plupart de ces éléments semblent appartenir à la fraction non-extractible des sols, la part biodisponible restante peut être détectée dans des bioindicateurs. Une relation négative entre les indices de condition et la concentration en plomb dans les animaux, et dans certains cas une plus grande instabilité de développement a été trouvée, suggérant la présence d’effets délétères sur les organismes. L’impact des anciens sites miniers et métallurgiques est donc toujours décelable dans les écosystèmes actuels. Ces sites doivent être surveillés, notamment au sein des zones protégées supposées à tort comme éloignées de toutes contaminations anthropiques. / The Morvan and the Cevennes Massifs are nowadays protected for their outstanding landscape and biodiversity. However since Prehistory, these regions experienced mining and smelting activities. Because of remnant properties, locating these ancient sites is capital and then impact on fauna and flora must be estimated. This present work is based in on a pluridisciplinary approach combining archeology, geochemistry, ecology and ecotoxicology. Statistical methods, from modern prospection technique, have been applied in order to delineate geochemical anomalies, potentially due to mining exploitation and thus facilitate the archeological prospection. Spatial distribution maps of trace metals were built on six sites (three in each park). Biodisponibility was assessed thanks to the analyses of wood mice, trout and bryophytes. Even if it seems that most of these elements belong to the non-extractible fraction of soil, the remaining bioavailable trace metals can be detected in the bioindicators. A negative relationship between Pb concentrations in animals and their body condition indices was found, and in some cases developmental instability was higher, suggesting deleterious effect on current wildlife. As a consequence, the impact of past mining and smelting works is still traceable in ecosystems. For this reason, these sites should be monitored, particularly in protected areas thought to be relatively free of anthropogenic contamination.

Diese Doktorarbeit beschäftigt sich mit theoretischen Aspekten der Wellenleiterelektrodynamik (WQED), also mit der Wechselwirkung von Materie und Licht, welches nur in einer Dimension propagieren kann. Dieses Forschungsfeld erfreut sich seit seiner Entstehung in den 1990er Jahren wachsender Beliebtheit, der Grund hierfür sind die mannigfaltigen Anwendungsmöglichkeiten, beispielsweise bei der Konstruktion von Quantencomputern als auch von klassischen Computern. Auch Vorschläge für sogenannte Pump-Probe-Experimente auf der Basis der WQED sind Gegenstand der aktuellen Forschung.\\ All diese Gebiete sind darauf angewiesen, die zugrunde liegenden Prinzipien zu verstehen, diese Arbeit soll einen Beitrag dazu leisten. Hierzu haben wir einen Formalismus entwickelt, der auf Feynman-Diagrammen fußt. Das erste physikalische Modellsystem, welches hiermit untersucht wurde, besteht aus einem 1D-Wellenleiter und einem daran gekoppelten Zwei-Nievau-Atom (ZNA). Dies erlaubte uns, bekannte Rechnungen physikalisch transparenter und mathematisch kompakter zu reproduzieren und auf beliebige Disperisonsrelationen zu erweitern. Wir nachweisen, dass die Näherung einer linearen Dispersion in vielen Fällen unzureichend ist, um bestimmte interessante Effekte (beispielsweise gebundene Atom-Photon-Zustände) zu verstehen. Im zweiten Teil der Arbeit wurde das System um ein zweites ZNA erweitert, was zum Auftreten von Fluktuationskräften führt. Diese wurden anhand des Beispiels der Förster Energie untersucht, welche den strahlungsfreien Anteil des Energietransfers beschreibt. Es wurde nachgewiesen, dass dies für unser Modellsystem im Rahmen der RWA der einzig relevante Anteil ist und ausserdem nur für beschränkte Dispersionsrelationen existiert. Wir konnten zeigen, dass sowohl die Stärke als auch die Form der zugehörigen Potentiale stark vom Anfangszustand des Systems abhängt. Dies eröffnet interessante Perspektiven für die Erzeugung maßgeschneiderter Kraftprofile zwischen beiden Atomen. / This PhD Thesis deals with the theoretical aspects of the so called waveguide quantum electrodynamics (WQED). This part of physics deals with the interaction of matter and light which is confined to just one spatial dimension. This area of science experiences growing importance since its formation in the 1990s. The main reason for this are the diverse application possibilities such as the construction of quantum computers as well as classical computers on an optical basis. Furthermore pump-probe experiments using WQED are a promising direction of current research. All this topics are relying on a exact understanding of the underlying physical processes and this thesis shall make a contribution to this. For this purpose we developed a formalism, which relies on Feynman diagrams. The first model system which was investigated in this context consists of a 1D optical waveguide coupled to a two level system (TLS). We where able to reproduce many known results in a physically more transparent and mathematically more compact fashion. Furthermore we generalized this results to arbitrary dispersion relation and showed that the approximation of a linear dispersion is insufficient to describe many physical effects, like atom-photon bound states for example.\\ In the second part of this work we generalized the model system by adding an additional TLS, which supports the occurrence of fluctuation forces. Those where investigated in great detail at the example of the Förster energy, which describes the radiationless part of energy fluctuations. It was shown that this is the only relevant contribution as long as the RWA is valid and only occurs for bounded dispersion relations. We proved that the strength as well as the shape of the corresponding potential strongly depends on the initial state of the system, which opens interesting perspectives for the creation of tailored force profiles between both atoms. All calculations where done analytically as well as numerically.

<p> <p>&nbsp / </p> </p> <p align="left">The current study aimed to describe the paradox of risk through an exploration of the experiences and perceptions of sexuality and HIV/AIDS among physically disabled young people in Nyanga, South Africa. This is against the background that AIDS has become a national and global crisis, which requires all people to participate in efforts to contain the pandemic. Yet literature indicates that young people with disabilities are not participating in such efforts. There is also an assumption, that physically disabled young people do not experience challenges in expressing their sexuality and accessing HIV/AIDS prevention services, to the same extent as other disability groups such as the blind and those with intellectual disabilities. Hence there was a need to explore disabled young people&rsquo / s own understanding of risk and the factors that hinder or support their participation in existing sexuality education and HIV/AIDS prevention programmes. It was also important for this group to suggest ways in which they may participate in such programmes.</p>

This investigation address the effect that pressure, p, and temperature, T, have on 4f-states of the rare-earth elements in the isostructural YbRh2Si2, EuCo2Ge2, and EuCu2Ge2 compounds. Upon applying pressure, the volume of the unit cell reduces, enforcing either the enhancement of the hybridization of the 4f-localized electrons with the ligand or a change in the valence state of the rare-earth ions. Here, we probe the effect of a pressure-induced lattice contraction on these system by means of electrical resistivity, from room temperature down to 100 mK. At ambient pressure, the electrical resistivity of YbRh2Si2 shows a broad peak at 130 K related to the incoherent scattering on the ground state and the excited crystalline electrical field (CEF) levels. At T_N = 70 mK, YbRh2Si2 undergoes a magnetic phase transition. Upon applying pressure up to p_1 = 4 GPa , T_N increases monotonously while the peak in the electrical resistivity is shifted to lower temperatures. For p &amp;lt; p_1 a different behavior is observed; namely, T_N depends weakly on the applied pressure and a decomposition of the single peak in the electrical resistivity into several shoulders and peaks occurs. Above p_2 = 9 GPa, the electrical resistivity is significantly reduced for T &amp;lt; 50 K and this process is accompanied by a sudden enhancement of T_N. Thus, our results confirm the unexpected behavior of the magnetization as function of pressure reported by Plessel et al. The small value of the magnetic ordering temperature for p &amp;lt; p_2 and the strength of the mechanism that leads to the peaks and shoulders in the electrical resistivity suggest that the f-electrons are still screened by the conduction electrons. Therefore, the observed behavior for pressures lower than p_2 might be a consequence of the competition of two different types of magnetic fluctuations (seemingly AFM and FM). Furthermore, the results suggest that a sudden change of the CEF scheme occurs at pressures higher than p_1, which would have an influence on the ground state. Additionally, a comparison of the pressure dependent features in the electrical resistivity of YbRh2Si2 with similar maxima in other isostructural YbT2X2 (T = transition metal; X = Si or Ge) compounds was performed. For the comparison, a simple relation that considers the Coqblin-Schrieffer model and the hypothesis of Lavagna et al. is proposed. A systematic behavior is observed depending on the transition metal; namely, it seems that the higher the atomic radii of the T-atom the smallest the pressure dependence of the maximum in the electrical resistivity, suggesting a weaker coupling of localized- and conduction-electrons. It is also observed that an increase in the density of conduction electrons reduces the pressure dependence of the characteristic Kondo temperature. The mechanism responsible for the sudden enhancement of T_N in YbRh2Si2 at about p_2 is still unknown. However two plausible scenarios are discussed. The Eu-ions in EuCo2Ge2 and EuCu2Ge2 have a divalent character in the range 100 mK &amp;lt; T &amp;lt; 300 K. Therefore, these systems order magnetically at T_N = 23 K and T_N = 12 K, respectively. The studies performed on EuCo2Ge2 and EuCu2Ge2 as a function of pressure suggest that a change to a non-magnetic trivalent state of the Eu-ions might occur at zero temperature for pressures higher than 3 GPa and 7 GPa, respectively. A common and characteristic feature on EuCo2Ge2 and EuCu2Ge2 is the absence of a clear first order transition from the divalent to the trivalent state of the Eu-ions at finite temperature for p &amp;gt; 3 GPa and for p &amp;gt; 7 GPa, respectively. In other isostructural Eu-based compounds, a discontinuous and abrupt change in the thermodynamic and transport properties associated to the valence transition of the Eu-ions is typically observed at finite temperatures. In contrast, the electrical resistivity of EuCo2Ge2 and EuCu2Ge2 changes smoothly as a function of pressure and temperature. The analysis of the the electrical resistivity of EuCo2Ge2 suggest that a classical critical point might be close to the AFM-ordered phase, being a hallmark of this compound. The overall temperature dependence of the the electrical resistivity of EuCo2Ge2 changes significantly at 3 GPa; therefore, it seems that the system suddenly enters to a T-dependent valence-fluctuating regime. Additionally, the pressure-dependent electrical-resistivity isotherms show a step-like behavior. Thus, it is concluded that discontinuous change of the ground state might occur at 3 GPa. The electrical resistivity of EuCu2Ge2 at high pressure is characterized by a negative logarithmic T-dependence in the pressure range 5 GPa &amp;lt; p &amp;lt; 7 GPa for T &amp;gt; T_N and by a broad peak in the pressure dependent residual resistivity, whose maximum is located at 7.3 GPa. The first behavior resembles the incoherent scattering process typical for an exchange coupling mechanism between the localized electrons and the ligand. This and the peak effect in the local 4f susceptibility observed in NMR measurements are consistent with such a coupling mechanism. Thus, it would be for the first time that a dense Eu-based compound like EuCu2Ge2 show such a behavior. Combining the results of the experiment performed at high pressures on EuCu2Ge2 with the studies performed in the EuCu2(Ge1-xSix)2 series, a crossover from an antiferromagnetically ordered state into a Fermi-liquid state for pressures higher than 7.3 GPa may be inferred from the analysis. Therefore, it may be possible that the sudden depopulation of 4f-level occur mediated by quantum fluctuation of the charge due to a strong Coulomb repulsion between the localized-electrons and the ligand. This phenomenon would explain the broad peak in the residual resistivity. To our knowledge, this would be the first Eu-based compound, isostructural to ThCr2Si2, that show such a transition as function of pressure at very low temperatures.

Enligt Carlsson och Rönnqvist (2005) och Frayret et al. (2007) blir det allt viktigare att arbeta med supply chain management inom trävaruindustrin. En utmaning är att finna ett arbetssätt för att hantera variationen i kundens efterfrågan. Idag hanteras variationen oftast genom onödigt stor lagerhållning (Lee et al., 1997b; So och Zheng, 2003).                                                                                 Syftet med studien är att utreda påverkande faktorer som bidrar till en varierande efterfrågan inom trävaruindustrin samt föreslå hur uppkomsten av dessa kan undvikas. För att svara på syftet har tre frågeställningar tagits fram och en fallstudie genomfördes på ett hyvleri. Informationsinsamlingen har skett genom intervjuer av anställda från olika avdelningar samt litteraturstudier. Studien visar att det finns flera utmaningar när det är stor variation på efterfrågan såsom brist på tillgång till prognoser och kommunikationsbrist med kunder. Det medför att planeringen av råvaruåtgången försvåras och det leder till svårigheter att uppnå leveransprecision.   Slutsatsen visar att de påverkande faktorer som bidrar till en varierad efterfrågan är prisvariationer, orderstorlek och orderfrekvens. Prisvariationer kan undvikas genom ABC-indelning av produkterna utifrån produktefterfrågan. Prognoser underlättar uppskattning av efterfrågan men för ett fungerande prognosarbete krävs samsyn, nära relation samt god kommunikation mellan kund och leverantör. Problem med orderstorlek och orderfrekvens kan reduceras om kunden får avgöra orderstorleken utan att specifika krav måste uppfyllas. Slutsatsen visar även att faktorer såsom väderlek, trender, mode, helgdagar och rotavdragets eventuella försvinnande påverkar variationen i efterfrågan. / According to Carlsson &amp; Rönnqvist (2005) and Frayret et al. (2007) supply chain management in the wood products industry is getting more important. One of the challenges is to find a way to deal with customer’s fluctuating demand. Traditional solution to handle fluctuating demand is large inventory (Lee et al., 1997b; So &amp; Zheng, 2003), which causes often high inventory cost for effective supply chain management.   The aim of the study is to investigate factors that affect a fluctuating demand in the wood products industry and suggest how to reduce the fluctuating demand through related factors analysis in order to improve Demand-Supply chain management efficiency. For this pursose, a case study on a planing is conducted. To collect data, interviews with employees from different departments have been made along with literature studies. The study presents that there are many challenges for the fluctuation demand such as lack of forecasts and lack of communication with customers. This, in turn, will cause problems with planning of the raw material as well as difficulties to deliver the goods on time.   The conclusion shows that the factors affecting a fluctuating demand are price variations, the orders batch size and order frequency. Price variations can be improved by ABC classification of the products by product demand. Forecasts will make the estimation of demand easier, although, in order to use forecasts properly a joint vision, close relationships and good communication with customer and supplier is required. Problems regarding batch size and order frequency can be reduced if the customer is allowed to decide the batch size with no specific requirements. The study also shows that factors such as weather, trends, fashion, holidays and disappearance of ROT work affects the fluctuating demand.

SUMMARY In the research work for Master degree the variance of morphological-physiological characteristics of the needles of Scots pine (Pinus sylvestris L.) growing in the vicinity of local pollution sources of Lithuania were investigated. Subject of research: Scots pine (Pinus sylvestris L.) growing near the largest industrial pollution sources in Lithuania: a cement factory, a nitrogen fertilizer factory and an oil refinery. Goals of the research: to estimate morphological and physiological features of the needles sampled from the pines growing at different distances from the largest industrial pollution sources. Methodology: the needle morphological features were determined by evaluating needle fluctuating length asymmetry and needle fluctuating mass asymmetry. The needle surface quality was evaluated by measuring contact angles of the water droplets and following the dynamics of water loss from excised needles. Research results: Significant differences were documented between the pine stands located at different distances from the cement factory. The needle asymmetry and surface data of the pine stand near the cement factory showed that the cement dust had a negative effect on the needle development and structure. The pine stand growing in the vicinity of the cement factory was characterised by increased needle asymmetry, faster water loss from the excised needles and increased surface wettability. No morphological and physiological changes as caused by air... [to full text]

<p> <p>&nbsp / </p> </p> <p align="left">The current study aimed to describe the paradox of risk through an exploration of the experiences and perceptions of sexuality and HIV/AIDS among physically disabled young people in Nyanga, South Africa. This is against the background that AIDS has become a national and global crisis, which requires all people to participate in efforts to contain the pandemic. Yet literature indicates that young people with disabilities are not participating in such efforts. There is also an assumption, that physically disabled young people do not experience challenges in expressing their sexuality and accessing HIV/AIDS prevention services, to the same extent as other disability groups such as the blind and those with intellectual disabilities. Hence there was a need to explore disabled young people&rsquo / s own understanding of risk and the factors that hinder or support their participation in existing sexuality education and HIV/AIDS prevention programmes. It was also important for this group to suggest ways in which they may participate in such programmes.</p>

Social amoebae are eukaryotic organisms that inhabit soil of almost every climate zone. They are remarkable for their switch from unicellularity to multicellularity as an adaptation to starvation. When starved, millions of single cells aggregate and form a multicellular fruiting body, which contains reproductive spore cells and dead stalk cells, which help in spore dispersion. This costly behavior made social amoebae a model system for addressing major questions of the evolution of cooperation and multicellularity. In this study we look at three different aspects of social amoebae behavior; aggregation, non-aggregation and competition, and ask how they contribute to our understanding of cooperation in social amoebae and microbial systems in general.We explored the known but neglected observation that, upon starvation, not all cells aggregate and engage in multicellular development. We describe phenotypically and genetically non-aggregating cell proportion in D. discoideum species. Both aggregating and non-aggregating strategy are costly or beneficial depending on duration of starvation. With our computational model we propose that partitioning the population into unicellular and multicellular states is adaptive in fluctuating environments with unpredicted duration of starvation periods. Social amoebae may therefore lie at the intersection of cooperation and bet-hedging. In the second part, we provide a new framework for addressing the contrasting observations of high genetic diversity in natural populations of social amoebae and experimentally suggested low diversity-high relatedness required for cooperation. We propose that complex life cycle of social amoebae provides multiple competition points that can possibly play an important role in maintaining diversity and cooperation. We explore this experimentally and computationally by looking at competition over the whole life cycle between 6 natural isolates of D. discoideum. Our simulation model indicates that competition at different stages of the life cycle can lead to exclusion of "social winners". Though we failed to explain strain coexistence. Although preliminary, our results emphasize the importance of integrating species ecology in cooperative studies.Finally, we focus on a new aggregation dynamics in P. pallidum species observed in our lab. Aggregation is a population level process during which population gets divided into numerous subpopulations/aggregates that face selection independently. Such population partitioning can have strong evolutionary consequences on cooperation that have not yet been explored experimentally. We describe the population dynamics qualitatively and propose several quantitative measurements of population partitioning into aggregates. Our preliminary results suggest that there is a preference for aggregates of certain size, but there is no spatial organization of aggregates.

Les organismes vivent dans des environnements dynamiques. Or la plupart des approches expérimentales étudient la fonction et la sélection des gènes dans des environnements statiques. De ce fait, la sélection naturelle agissant en environnements fluctuants reste mal comprise. L´objectif de mon projet a été de déterminer si certains gènes sont particulièrement importants pour la fitness (taux de croissance) de cellules de levures en environnements oscillants. Un crible génomique, basé sur une automatisation de micro-cultures et sur un multiplexage de banques de séquençage, m´a permis de mesurer la fitness de milliers de mutants nuls en conditions de stress périodique. J´ai trouvé que la prédictibilité de la fitness en environnements périodiques, à partir de la fitness en environnements statiques, diffère selon les gènes et les conditions. Ainsi, certains mutants présentent des croissances similaires en conditions statiques mais différentes en conditions dynamiques. Curieusement, quelques gènes jouent un rôle bivalent : ils favorisent fortement la croissance lors de fluctuations lentes et ils la défavorisent lors de fluctuations rapides. J´ai également observé de nombreux mutants avec une croissance plus élevée qu´attendue aux fréquences de fluctuations les plus rapides. Cet effet s´explique partiellement par une perte de sensibilité environnementale de ces mutants, qui continuent à se diviser rapidement malgré la présence d´un stress. Ces résultats montrent comment la sélection naturelle agit sur les mutations en environnements fluctuants. Ils ouvrent la porte à des études mécanistiques de la prédictibilité de la fitness en environnements périodiques. / Organisms live in dynamic environments. However, most experimental approaches study the function and selection of genes in steady environments. Therefore, natural selection acting on fluctuating environments remains poorly understood. The objective of my project was to determine if some genes are especially important for fitness (growth rate) of yeast cells in oscillating environments. A genomic screen, based on an automation of micro-cultures and on a multiplexing of sequencing libraries, allowed me to measure fitness of thousands of null mutants in periodic stress conditions. I found that predictability of fitness in periodic stress, from fitness in steady environments, varies depending on the specific genes and conditions considered. This way, some mutants have similar growth in steady conditions, and different growth in dynamic conditions. Curiously, some genes play a bivalent role: they strongly favor growth during slow fluctuations, and reduce it during fast fluctuations. I also observed many mutants with higher growth than expected at the highest frequencies of fluctuations. This effect can be partially explained by a loss of environmental sensitivity of those mutants, that continue to divide quickly despite the presence of a stress. Those results show how natural selection can act on mutations in fluctuating environments. They open the door to mechanistic studies of the predictability of fitness in periodic environments.

Philosophiae Doctor - PhD / The current study aimed to describe the paradox of risk through an exploration of the experiences and perceptions of sexuality and HIV/AIDS among physically disabled young people in Nyanga, South Africa. This is against the background that AIDS has become a national and global crisis, which requires all people to participate in efforts to contain the pandemic. Yet literature indicates that young people with disabilities are not participating in such efforts. There is also an assumption, that physically disabled young people do not experience challenges in expressing their sexuality and accessing HIV/AIDS prevention services, to the same extent as other disability groups such as the blind and those with intellectual disabilities. Hence there was a need to explore disabled young people’s own understanding of risk and the factors that hinder or support their participation in existing sexuality education and HIV/AIDS prevention programmes. It was also important for this group to suggest ways in which they may participate in such programmes. A qualitative case study design was chosen as the appropriate means for achieving the aim of the current study. This design allowed me to study disabled young people without separating them from their context. In this way, a comprehensive understanding of this group was realised. Multiple methods of data collection from multiple data sources were employed, a feature that helped to discuss the ‘case of disabled young people’ in-depth and breadth. Policy and programme documents and relevant literature were reviewed for relevant information on sexuality education and HIV/AIDS prevention services for disabled young people. Fifteen disabled young people between the ages of 15 and 24 participated in individual in-depth interviews and in focus group discussions. Pertinent issues that arose from individual interviews were discussed with 15 parents, 15 senior citizens, five sangomas and five counsellors in focus group discussions of 4-10 members each. Similar issues from focus group discussions were taken up with eight key informants in more individual in-depth interviews for confirmation and clarity. Textual and contextual features of the Atlas.ti computer programme for analysing qualitative data were used to organize and analyse data. The textual features were used to code data and write memos, while the contextual features were used to link the codes and to form networks from which categories and themes were generated. Themes and sub themes were used to answer the research questions and meet the objectives of the study. The study has revealed a complex interplay of contextual and individual factors that combine to create situations of risk for disabled young people. These factors affect disabled young people’s experiences of growing up and participation in existing sexuality education and HIV/AIDS prevention programmes. Contextual factors include cultural beliefs and poverty, while individual factors include sexual behaviour and attitude towards HIV risk. I found that disabled young people have limited access to education and other social amenities, which in turn affect their experiences of life in general and sexuality and HIV/AIDS. The study has revealed that the paradox of risk lies in the contradictory scripts and attitude towards the pandemic at contextual and individual levels. The belief that disabled young people are asexual is common in Nyanga, yet society targets this group for sexual exploitation and rape. In the face of an epidemic that has crippled the fabric of society, and in spite of the widespread availability of HIV/AIDS awareness programmes, most disabled young people still do not have accurate factual knowledge about HIV/AIDS. Yet accurate information is one of the prerequisites for making informed decisions about HIV/AIDS prevention. Furthermore, gender differences make the experiences described above more serious for disabled young women who suffer discrimination and sexual abuse even from fellow disabled young men. Although most disabled young people indicated that they are aware of the gravity of the pandemic and that they personally feel threatened, they are not taking preventive measures against contracting the infection; they have adopted a fatalistic response to risk. Participants argue that in the same way they are not able to protect themselves from going hungry, or living in shacks, they also cannot prevent getting infected with HIV, which they equate to any accident over which they have no control. Disabled young people expressed the need to participate in mainstream education systems, sexuality education and HIV/AIDS prevention programmes. They also pointed out that there will always be disabled young people who require separate programmes because of special disability circumstances such as inability to travel to clinics/centres. In order to meet disabled young people’s expressed wishes, I have recommended in this thesis, a community-based sexuality education and HIV/AIDS prevention programme that focuses on the whole community instead of individuals only so as to deal with contextual and individual factors of risk. Such a programme encourages dialogue and participation as opposed to the information giving approaches from experts. A guideline that existing HIV/AIDS intervention programmes can use to include disabled young people’s special circumstances, has been presented. / South Africa