Dissertations / Theses on the topic 'Dive behaviour'

Narwhals (Monodon monoceros) are sentinel species in the Arctic environment and are a vital component for Inuit culture and subsistence. The Arctic is undergoing rapid changes in temperature and sea ice cover and relatively little is known about how this has and will change narwhal foraging behaviour. There are three narwhal populations in the world, the Baffin Bay (BB), Northern Hudson Bay (NHB), and East Greenland (EG) populations; however, foraging behaviour, in terms of dive behaviour and primary dietary components, has really only been investigated in the BB population. Using a combination of stable isotopes, fatty acids, genetic techniques, and satellite tracking technologies I evaluated foraging behaviour in all three of the world’s narwhal populations. I also investigated social structure in the BB population to determine how adaptable narwhals are to a changing and dynamic Arctic environment. Stable isotopes (δ13C and δ15N) and fatty acids are chemical signatures in the tissues of an organism that can provide long-term information on their diet over varying temporal scales depending upon the tissue. Stable isotope analysis in the three narwhal populations found they forage on different primary prey, suggesting narwhal are adaptable in their preferred prey and that there is potential for them to adjust foraging behavior in the face of changing climate. Dietary changes were also assessed over three decades to determine how sea ice changes have affected narwhal foraging for the NHB and BB populations. Dietary changes were evident and can be attributed to changes in sea ice patterns and an altered migratory pathway for narwhals. An understanding of narwhal social structure is also needed to determine how behaviourally flexible narwhal are in diet and site fidelity. Genetic relatedness and dietary signatures from fatty acids were assessed for an entrapped group to determine if individuals that are closely related forage together, which would support a matrilineally driven social structure where females teach their young foraging strategies, and/or travel and forage together. I found no evidence that narwhals form a matrilineal social group, but they may display a fission-fusion structure, which may be an adaptation to patchy prey distribution in the Arctic. Finally, narwhal dive behaviour in all three populations was investigated to determine if dive behaviour could be used to predict diet. Dive differences among populations did correspond with differences in diet, suggesting that narwhals employ specialized foraging strategies. This has repercussions for their ability to adapt to ecosystem changes. Overall, narwhals may be more flexible in terms of their foraging behaviour than previously believed. However, an increased resilience to changing food webs will not be the only predictor of how narwhals will fare in the face of a changing climate; how they respond to increased industrial activities in their preferred habitats, increased predation from southern predators, and increased competition from southern cetaceans and humans alike, will play an equally large role in how they cope with the future.

A mathematical but mechanistic model is presented that is based upon the simplified physiology and feeding ecology of an individual dive foraging animal. In previous theoretical studies of dive foraging behaviour, models assumed dive foraging animals dive optimally based on oxygen as the sole state variable, thus ignoring other likely important physiological factors that are related to the instantaneous energetic requirements of the diving animal. The physiological mechanistic dive foraging model presented includes the additional state variables, namely food (in the gut) and the body mass of the diving animal, for which the oxygen is ultimately required to burn for energy. The physiological model was parameterised for the Common Guillemot Uria aalge, although it may also be applied to other dive foraging animals. Various output parameters are possible from the model, and these were generated from computer simulations to investigate the merits of optimal diving behaviour. The physiological dive foraging model was also used to estimate possible feeding rates of Guillemots from fisheries data made available, which were recorded during winter 1997, in the Moray Firth. These were then used in further computer simulations of the dive foraging model and the various possible output parameters obtained from the model were subsequently used as habitat suitability indices in a novel application of the Ideal Free Distribution, to generate predicted maps of Guillemot distribution, which were tested against the actual concurrently recorded distribution of Guillemots in the Moray Firth. The potential value of the physiological dive foraging model, its limitations and where it, or how its predictions, may further improve, are also discussed. It is hoped that the model will eventually provide an invaluable tool for industrial fisheries, and even wider marine ecosystem management.

L’océan austral est un écosystème fragile dont la dynamique est influencée par des variations climatiques qui vont structurer la distribution spatio-temporelle des ressources. L’objectif de cette thèse était d’étudier les stratégies d’acquisition des ressources en proies mises en place par l’éléphant de mer austral face aux contraintes énergétiques (coûts du transport et coûts d’accès à la ressource) et temporelles (temps passé au fond d’une plongée et limite de plongée aérobie) auxquelles il est soumis. L’utilisation d’un ensemble d’enregistreurs de données déployés sur ces animaux a permis de reconstruire en trois dimensions leur plongée, mais également de calculer leur effort de nage, le nombre de proies rencontrées ainsi que leur dépense énergétique. Notre étude montre qu’à l’échelle d’une plongée, les éléphants de mer adaptent leur trajectoire, mais également le temps qu’ils passent au fond, en fonction du nombre de proies rencontrées. Pour des densités locales de proie importantes, ils passent plus de temps au fond, et concentrent leur recherche en zone restreinte, caractérisée par une diminution de la vitesse et une augmentation de la sinuosité horizontale. Au-delà de 550 m, le coût d’accès aux ressources devient supérieur aux coûts d’acquisition ; ils doivent alors faire face à un compromis entre l’accessibilité et la disponibilité en proies. À mesure qu’ils s’alimentent, ces phoques augmentent leur flottabilité, diminuant de surcroît leur dépense énergétique. Cette étude démontre également une structuration spatio-temporelle de cette dépense énergétique qui semble être liée au succès d’alimentation et donc à la distribution des ressources en proies
The Southern Ocean is a fragile ecosystem whose dynamics are influenced by climate change that will structure the spatio-temporal distribution of resources. The objective of this PhD was to investigate the foraging strategies used by the southern elephant seal, under energetic (cost of transport and costs of access to the resource) and temporal (time at the bottom of a dive and aerobic dive limit) constraints. Using a set of animal-borne data loggers allowed us to reconstruct their three-dimensional path underwater, but also to calculate their swimming effort, the number of prey encountered and their energy expenditure. At the dive level, our study shows that elephant seals adapt their path, but also the time spent at the bottom, depending on the number of prey encountered. For high local prey density, they spent more time at the bottom, and concentrated their foraging effort in areas restricted search, characterized by a decrease in speed and an increase in horizontal sinuosity. Beyond 550 m, the cost of access to resources becomes greater than the cost of acquisition ; they must therefore deal with a trade-off between prey accessibility and availability. While feeding, these seals increase their buoyancy, reducing furthermore their energy expenditure. This study also shows a spatio-temporal structure of the energy expenditure that appears to be related to feeding success and therefore to prey resources distribution

Weddell seals (Leptonychotes weddellii) are among the deepest diving pinnipeds (i.e., seals, sea lions, and walrus) and one of the best studied marine mammals in the world; as such, these seals are considered a model species for the study of diving physiology and behavior. Adult Weddell seal dive physiology is rather comprehensively understood, yet previous research has excluded an examination of pups’ initial independent diving attempts, beginning instead with the diving capabilities of near-weaning individuals at four to five weeks of age. This is beyond the point many pups have attempted their first independent dives; pups begin to enter the water at 8-10 days after birth, with some observed in the water earlier. The aim of this study was to investigate the development of diving capabilities and fine-scale behaviors of Weddell seal pups beginning at one week of age throughout their dependence period. Pups were sampled longitudinally at 1, 3, 5, and 7 weeks of age. Total body oxygen stores (TBO2, mL O2) were calculated as the sum of blood, muscle, and lung oxygen stores for each seal at all time points. Blood samples were collected under sedation, muscle oxygen parameters were interpolated, and lung oxygen content was extrapolated from adult values. Flipper-mounted time-depth recorders were used to collect concurrent dive behavior data. In chapter 1, I hypothesized that diving capability (TBO2) would be more strongly correlated with dive experience than calendar age; to examine this, age, mass, and diving parameters were correlated with oxygen stores. I instead found mass and age were most significantly correlated with individual tissue oxygen stores and TBO2. I predicted diving experience would be an important driver of oxygen storage development due to hypoxia exposure, but pups spent the majority of their time in the water at the surface and had little to no exposure to hypoxia during dependence. Increases in mass may enable early advances in diving ability, and with increased diving capabilities, pups will be able to become successful independent foragers. Later exposure to hypoxia may be the key to the subsequent increases in TBO2 observed in yearlings and juveniles. In chapter 2, I used TDR data to predict when pups would be in the water based on developmental, temporal, and environmental factors including age, weaning status, time of day, and weather parameters. Pups spent the most time in the water and made their deepest, longest, and most frequent dives during the late night and early morning hours. These data indicate pups are following the diving patterns of their mothers, which follow the diurnal vertical migration of their prey. The data also suggest Weddell seal pups most likely prioritize learning to swim and navigate as opposed to practicing foraging while still dependent. It is critical for pups to develop their swimming, navigational, and diving abilities while they are still with their moms to ensure their survival. This study is the first to describe the complete trajectory of the development of diving physiology and behavior in Weddell seal pups throughout dependence. It is important to understand how the internal diving physiology of Weddell seal pups develops because this directly determines their diving capabilities and their ability to forage successfully, which in turn directly correlates with their survival. Pup survival is an indicator of population growth rates, so the development of diving physiology in pups can lend insights into larger population-level trends.

During the last few years, awareness of environmental- and health related problems have grown dramatically. An area that has a contributed to these concerns are the food industry. It has affected the demand of greener products such as organic food, which aims to be healthier and better for the environment. Although there are different views on the exact benefits of organic food, it is considered to have a general positive effect on its surroundings. However, organic food has been costly, both for farmers and consumers, which has created an imbalance in supply and demand for organic products. Even if the sales of organic food has increased, the consumption is not enough for prices to decrease. It has also been found that people claim to buy that they buy organic to a higher extent than they actually do. Therefore this thesis focus on understanding how sales of organic food can be increased further, by identifying existing customer values and brand knowledge about organic products, in order to use the findings to improve problem areas and change buying behavior. The result is based on several research methods, although the greatest part comes from empirical tests examine the research questions derived from earlier research and interviews. The tests main focus was to investigate perceptions about price sensitivity, the effect of place and promotion, and finally the effect of clarifying the concept of organic food through arguments on the packages. The main conclusion is that the greatest opportunity to change consumer behavior towards buying more organic products is held by the retailers. The majority of all decisions are made in store, which is why the greatest change to influence consumer behavior is located there. Down- and upstream activities are recommended depending on the customer’s readiness to change purchase behaviors into new once. However, further studies of the arguments actual impact on sales are proposed to be further studied, and has been left out due to the limited scope of the tests and the possibility to measure it. Also, further research on to what extent the customer is willing to let the retail chains take decisions for them is proposed.
Under de senaste åren har medvetenheten om miljö- och hälsorelaterade problem ökat dramatiskt. Ett område som har bidragit till denna oro är livsmedelsindustrin. Detta har påverkat efterfrågan på miljövänliga produkter som ekologiska livsmedel, vars syfte är att främja hälsa och miljö. Även om det finns olika uppfattningar om de exakta fördelarna med ekologisk anses det i allmänhet ha positiva effekter på omgivningen. Ekologiska livsmedel är dock kostsamt, både för jordbrukare och konsumenter, vilket har skapat en obalans i utbud och efterfrågan. Även om försäljningen har ökat, är konsumtionen inte tillräcklig för att priset ska minska. Det har också visat sig att människor ofta utger sig för att köpa ekologiska produkter i högre grad än vad de faktiskt gör. Därför avser denna studie att analysera hur försäljningen av ekologiska livsmedel kan öka ytterligare genom att identifiera befintliga kundvärderingar och varumärkes kunskap om ekologiska produkter för sedan använda resultaten till att förbättra problemområden och förändra köpbeteendet. Resultatet bygger på flera forskningsmetoder, även om den största delen kommer från empiriska tester som undersöker forskningsfrågor skapade utifrån tidigare litteraturen på området samt intervjuer. Testernas huvudfokus var att pröva uppfattningar om priskänslighet, effekten av produktplacering och uppmärkning, samt effekten av förtydligande argument av ekologiska produkters innebörd. Den viktigaste slutsatsen av denna studie är att den största möjligheten att ändra konsumenternas beteende till att köpa mer ekologiska produkter innehas av återförsäljarna. Majoriteten av alla beslut fattas i butiken, vilket gör att de har störst möjlighet att påverka. Ned- och uppströms aktiviteter rekommenderas beroende på kundens benägenhet att ändra beteende. Det krävs dock ytterligare studier på argumentens inverkan på försäljningen Ytterligare forskning om hur villig kunden är att låta butikskedjorna fatta beslut åt dem rekommenderas.

[For the Abstract, please see the PDF files below, namely "front.pdf"] CONTENTS. Chapter 1 Introduction. Chapter 2 Gross and microscopic visceral anatomy of the male Cape fur seal with reference to organ size and growth. Chapter 3 Age determination and growth in the male Cape fur seal: part one, external body. Chapter 4 Age determination and growth in the male Cape fur seal: part two, skull. Chapter 5 Age determination and growth in the male Cape fur seal: part three, baculum. Chapter 6 Suture age as an indicator of physiological age in the male Cape fur seal. Chapter 7 Sexual dimorphism in the adult Cape fur seal: standard body length and skull morphology. Chapter 8 Reproduction in the male Cape fur seal: age at puberty and annual cycle of the testis. Chapter 9 Diet and foraging behaviour of the Cape fur seal. Chapter 10(a) The Impact of the fur seal industry on the distribution and abundance of Cape fur seals. Chapter 10(b) South African Airforce wildlife rescue: Cape fur seal pups washed from Black Rocks, Algoa Bay, during heavy seas, December 1976. Chapter 11(a) Operational interactions between Cape fur seals and fisheries: part one, trawl fishing. Chapter 11(b) Operational interactions between Cape fur seals and fisheries: part two, squid jigging and line fishing. Chapter 11(c) Operational interactions between Cape fur seals and fisheries: part three, entanglement in man-made debris. Chapter 12 Concentrations of heavy metals (Cd, Cu, Pb, Ni & Zn) and organochlorine contaminants (PCBs, DDT, DDE & DDD) in the blubber of Cape fur seals. Chapter 13 Endoparasites of the Cape fur seal. Chapter 14(a) Preliminary investigations of shark predation on Cape fur seals. Chapter 14(b) Aggressive behaviour of an adult male Cape fur seal towards a great white shark Carcharodon carcharias. Chapter 15 Conclusions and future directions.

Buying behaviour is a complex, wide– ranging field, intricately associated with human mental processes, responding to environmental stimuli. Understanding the customer and being able to predict their behaviour, is of prime importance to all marketers and marketing strategists for two reasons: Firstly because, the overall strategy of the company has to be clearly reflected in the marketing strategy for any meaningful progress. Secondly, to be able to adjust or adapt the marketing effort to changing marketing conditions. The focus of this study is to research the buying behaviour of farmers through the marketing mix paradigm. Although slightly contentious in terms of recent theories and field of application, the dichotomous nature of farmers buying behaviour and the characteristics of the purchase makes this theory a good fit for the circumstances. The marketing mix theory focuses on the controllable external stimuli which reinforces the practical application of this study. The buying behaviour of farmers was researched by asking farmers to evaluate the importance of a statement related to an element of the marketing mix theory by telephonic interview. The answers of the farmers were analysed using various statistical methods and the following salient results were obtained: All the elements of the marketing mix theory are important to farmers when deciding on buying a new tractor. The less experienced farmers rated all the elements of the marketing mix as more important than more experienced farmers. There was a definitive subset of farmers for whom the more changeable part of the marketing mix, price and promotion, had a definite impact on their decision. Price and promotion did not correlate with farmers who viewed the product of high importance. Other results indicated that the farmers in the test sample bought a new tractor every 2.3 years with 54% of farmers buying a new tractor in the past year. The frequency with which farmers buy new tractors shows the importance of the market. The finding that the elements of the marketing mix theory are important to farmers was expected and could serve as an incentive for future research. The marketing mix theory is viewed as highly applicable in this case, due to its relative simplicity and the focus on the more controllable stimuli on the farmer. It was also found that for a significant subset of farmers the more modifiable elements had a definitive impact on their decision when buying a tractor. This offers an opportunity to marketers willing to respond to changing uncontrollable conditions to influence buying decisions in the short term.
Thesis (M.B.A.)--North-West University, Potchefstroom Campus, 2012.

In cold forming operations, tool geometry has a direct influence on the product quality, forming force, load acting on dies and tool life. Finite element method provides a means to analyse these parameters to predict forming defects and die failures. In this study, shrink fitting the components of a bolt forming die is modelled and the finite element results are compared with the analytical solutions and experiments. In order to perform die stress analyses, deformable die models are implemented in the forging simulations. Furthermore, effect of using rigid and deformable dies on the stress distributions in the tools, forming force and product dimensions are examined. Some applications of tool geometry improvements and optimization of prestressing are presented in the case studies. In the second part of the study, the appropriate friction model for the cold forming operation of bolts is investigated. For this purpose, ring compression and forward rod extrusion tests are conducted. Dimensional variations and deformation forces are compared with the finite element simulations performed for different friction models and constants. The results of shrink fit analyses of die prestressing are in good agreement with the elasticity formulations and real applications. In the studied bolt production cases, after improving the die stress distributions by using FE simulations, longer tool lives are achieved. Finally, for more accurate results, Coulomb friction model is determined as an appropiate model for bolt forming analyses.

The domain below the surface in maritime security is hard to monitor with conventional methods, due to the often very noisy environment. In conventional methods the measurements are thresholded in order to distinguish potential targets. This is not always a feasible way of treating measurements. In this thesis a system based on raw measurements, that are not thresholded, is presented in order to track and classify divers with an active sonar. With this system it is possible to detect and track weak targets, even with a signal to noise ratio that often goes below 0 dB.

The system in this thesis can be divided into three parts: the processing of measurements, the association of measurements to targets and the classification of targets. The processing of measurements is based on a particle filter using Track Before Detect (TBD). Two algorithms for association of measurements, Joint Probabilistic Data Association (JPDA) and Highest Probability Data Association (HPDA), have been implemented. The classification of targets is done using an assumed novel approach. The system is evaluated by doing simulations with approximately 8 hours of recorded data, where divers are present at nine different times. The simulations are done a number of times to catch The classification rate is high and the false alarm rate is low.

Undervattensdomänen är svår att övervaka i marina säkerhetssystem med sedvanliga metoder, på grund av den brusiga miljön. I traditionella metoder trösklas mätningarna för att urskilja potentiella mål. Detta är inte alltid ett godtagbart sätt att behandla mätningar på. I den här rapporten presenteras ett system baserat på behandling av rå mätdata, som inte trösklas, för att spåra och klassificera dykare med en aktiv sonar. Med detta system är det möjligt att detektera och spåra svaga mål, trots att signal till brus förhållandet ofta går under 0 dB.

Systemet i den här rapporten kan delas upp i tre delar: behandling av mätningar, association av mätningar till mål samt klassificering av mål. Behandlingen av mätningarna görs med ett partikelfilter som använder Track Before Detect (TBD). Två algoritmer för associering av mätningar, Joint Probabilistic Data Association (JPDA) och Highest Probability Data Association (HPDA), har implementerats. Klassificeringen av mål görs med en egenutvecklad metod som inte har hittats i existerande dokumentation. Systemet utvärderas genom att simuleringar görs på ungefär 8 timmar inspelad data, där dykare är närvarande vid nio olika tillfällen. Simuleringarna görs ett antal gånger för att fånga upp stokastiska beteenden. Andelen lyckade klassificeringar är hög och andelen falsklarm är låg.

Les solides divisés telles que les poudres pharmaceutiques nécessitent souvent des processus d'agrandissement de taille par agglomération pour améliorer leur comportement mécanique, notamment la coulabilité. Pour cette raison, le procédé de "granulation en voie sèche" est utilisé dans l'industrie pharmaceutique. Le procédé consiste à comprimer la poudre en la faisant passer entre deux rouleaux séparés par un entrefer, pour produire des plaquettes qui sont ensuite broyées en granulés et comprimés en compacts. Dans ce procédé, l'existence de différents modèles de compacteurs à rouleaux et de systèmes de broyage d’une part, et l'interaction entre les paramètres des procédés et des propriétés des produits (plaquettes, granulés et comprimés) d’autre part, rendent difficile la compréhension des phénomènes et des mécanismes sous-jacents. En particulier, le procédé entraîne une perte de résistance mécanique des comprimés formés à partir de granulés (comparativement à celles des comprimés de poudres non-granulés) et ce phénomène est encore mal compris. Ces aspects sont étudiés dans ce travail de thèse en menant des caractérisations expérimentales et des modélisations numériques permettant de mieux comprendre les modifications micro et macro structurales des poudres mises en forme par granulation sèche. Le but ultime est de progresser dans la compréhension des relations "propriétés des poudres - paramètres des procédés". Enfin, la compréhension des différences de comportement en compression de poudres granulées et non-granulées est menée à l’aide d’une modélisation du comportement dans le cadre de la mécanique des milieux continus poreux
Particulate solids such as pharmaceutical powders often require size enlargement processes to improve the manufacturing properties like flowability. For that reason, dry granulation by roll compaction has been widely used in the pharmaceutical industry. The process consists of compressing powders between two counter-rotating rolls to produce ribbons that will be subsequently milled into granules. The obtained granules are tableted for oral dosage. In this process there are two main limitations: the existence of different designs of the roll compactors, milling systems and the interaction between process parameters and raw material properties are still a challenge and the roll-compaction process leads to an inferior tensile strength of tablets compared with direct compression. These aspects are investigated in this work. In the first part of this thesis, an analysis on the effect of different roll-compaction conditions and milling process parameters on ribbons, granules and tablet properties was performed, highlighting the role of the sealing system and the ribbon density distribution characteristics. In the second part, die compaction of roll-compacted powders, as the last stage of the process, is further investigated in terms of experimental analysis (effect of the granule size and composition and stress transmission measurements) and modelling the compaction behavior of granules

Thesis (DPhil (Psychology))—University of Stellenbosch, 2006.
This study has two purposes which are complementary: Firstly, an alternative prevention intervention was developed in order to introduce narrative group therapy as a therapeutical practice within preventative interventions in South Africa. Secondly, a training protocol was developed which can be used to train psychologists, counsellors, social workers, teachers and relevant persons to apply narrative group therapy as an alternative preventative intervention in their communities. In the context of this study, the personal stories of the adolescents who took part in this study reflect the problem stories of the Jamestown and Cloetesville community near Stellenbosch. After identifying 20 adolescents who experience problem stories with high-risk themes at two secondary schools in the respective communities, ten narrative group sessions were held, with social constructionism as philosophical approach. The training protocol was primarily of an experiential nature, consisting of 40 hours of training and 12 hours of supervision, with special focus on the personal stories of the four master’s degree psychology students who underwent training and facilitated the group therapy with the adolescents. For the purpose of this study qualitative research was done. During the development of the alternative preventative intervention, a qualitative description was given of the content of the personal stories of the adolescents within the interactional space of narrative group therapy and personal stories. The focus during this qualitative description was the following: • to establish whether the therapeutic process facilitated change, • to develop a new understanding of the therapeutic process by specifically focusing on applying narrative therapy in a group, and • to train and empower narrative-group-therapy facilitators to facilitate the narrative- group-therapy process. In this study two narrative-analytical research methods were used. Firstly, a qualitative narrative-analysis method was used to evaluate the psychotherapeutical transcripts. A part of these sessions was dedicated to this purpose and is presented in transcribed format. Secondly, the content-analysis method was applied: session data was examined, categories of the adolescents’ and students’ narratives were defined and thematic statements were extracted from the text, classified and sorted into categories or groups. This study provides supportive evidence that narrative group therapy as an alternative preventative intervention can be introduced as a therapeutic practice in South Africa. In addition, an effective training protocol was developed which can be used to train psychologists, counsellors, social workers, teachers and other relevant individuals to use narrative group therapy as an alternative preventative intervention in their communities.

Thesis (MSc (Botany and Zoology))--University of Stellenbosch, 2006.
Although the Bengal tiger, Panthera tigris tigris, appears on the IUCN Red Data List for endangered animals, very little information is available in the literature on the components of this animal's marking fluid. Scent marking is the main form of communication in all cat species. In some species, including the Bengal tiger, the liquid used for spraying is not pure urine, but is mixed with scent gland secretions. The objective of this study was to characterise the volatile components in the marking fluid of the Bengal tiger to achieve a better understanding of the semiochemical communication of this animal. The marking fluid of the tiger was characterised through the use of analytical techniques, such as gaschromatography, low resolution gas chromatography - mass spectrometry and retention time comparison. Homologous series of alkanes, alcohols, aldehydes, methyl ketones, carboxylic acids, γ- and δ-lactones, amides and lactams, as well as esters and nitrogen containing compounds, were identified. Of these identified compounds the unbranched alkanes, saturated alcohols, aldehydes, branched methyl ketones, saturated carboxylic acids and γ- and δ- lactones are commonly found in mammalian secretions. Compounds that aren't as common in their secretions are the methyl ketones, branched carboxylic acids, dimethyl esters of dicarboxylic acids and amides. The marking fluid contains a phthalic acid ester. Phthalic acid esters are used in the polymer industry and are nowadays found almost everywhere in nature. It is known that these pollutants have endocrine disrupting properties. The heat, humidity and wet conditions that are characteristic of the Bengal tiger's natural habitat makes it necessary for the tiger to make use of a fixative to prolong the life of the semiochemical message. The compounds and the concentrations in which these compounds are present in the urine and the lipid fraction of the marking fluid of the tiger was determined and compared to assess the fixative role of the lipids. This study has provided evidence that the lipid material has a greater affinity for the volatile organic constituents of the marking fluid and that it can therefore extend the lifetime of a semiochemical message left by the tiger.

Air-breathing divers, such as marine mammals, should adjust their diving behaviours in relation to the depth and density of their prey to minimize the energetic costs and maximize the benefits of foraging. However, there is little experimental data to test these predictions or to develop models to predict the responses of marine mammals to changes in prey availability. The objectives of my study were to 1) determine how changes in prey availability affect dive behaviour and foraging efficiency in Steller sea lions (Eumetopias jubatus) and 2) develop models with data from free-diving captive Steller sea lions to estimate foraging costs in wild animals and evaluate energetic trade-offs between different foraging strategies. I measured the diving metabolic rate, dive durations, and food intake of 4 trained sea lions diving in the open ocean on simulated prey patches of high- or low-densities at 10 m and 40 m. I also measured diving metabolic rates of sea lions performing 4 controlled dive types that allowed me to estimate the separate costs of different dive components (i.e., surface time, bottom time, and transiting to and from depth). I found that animals diving on prey patches with low prey density altered their dive behaviours and spent proportionally less time actively foraging, which ultimately decreased their foraging efficiency. I also found that making single, longer dives were less energetically costly than making multiple shorter dives in a bout, but that the sea lions replenished oxygen stores more efficiently when making a bout of dives. Finally, I determined the metabolic cost of transiting to and from depth (20.5±13.0 ml O₂ min₋¹ kg₋¹) was greater than the cost of foraging during the bottom portion of a dive (13.5±4.1 ml O₂ min₋¹ kg₋¹). With these values, I generated a predictive equation to estimate the diving costs of free-ranging animals. Overall, my results indicate that Steller sea lions do alter their dive behaviour in relation to prey availability and that different foraging strategies have different energetic costs. These results can be used to understand how changes in prey availability affect the overall energy balance and health of Steller sea lions.
Science, Faculty of
Zoology, Department of
Graduate

Thesis (MTh)--Stellenbosch University, 2015.
ENGLISH ABSTRACT: This study examines the value that body theology can add to an inclusive understanding of sexuality in adolescence. Sexuality was understood differently throughout different periods in time, but even today there is still no real clarity on what is meant by the term sexuality. Sexuality is a difficult term to define and its meaning plays an important role in the way people treat each other. Throughout the different periods the church has largely been either silent about sexuality or considered it a sin. As a result the church would not necessarily be seen as a good resource for advice on sexual matters. Adolescents go through a dramatic period of developing on a physical, cognitive and moral level, which all occur simultaneously, but sexual development is the most prominent. Sexual development prepares adolescents on a physical level to reproduce and to enter into sexual relationships, but cognitive and moral development also takes place; these two processes are supportive for the adolescent to understand and process the sexual development. These developing processes, together with the context in which an adolescent is growing up, has an impact on the type of moral value system compiled by adolescents, which determines how they behave. As already mentioned, the church is not necessarily involved in these discussions, and therefore this study challenges the churches to become involved again by making use of body theology. The research question can be formulated as follows: What contribution can body theology make to promote an inclusive understanding of sexuality during adolescence? To answer the research question, the first objective is discussed in chapter 2, namely to give a historical overview to obtain an understanding of sexuality and see how the understanding of sexuality changed over the different periods, but also to see that there were certain times when the understanding of sexuality was the same. The second objective is discussed in chapter 3, where the focus is on a historical overview of the understanding of the body. This historical overview is discussed to understand that the body often stood in an ambiguous position and dualisms formed part of the understanding of the body, but it also affects a deeper understanding of life. In chapter 4, the third objective is discussed by examining the centrality of sexual development during adolescence to understand the important role that sexual development plays in the adolescent's life, but also to realise that it affects other aspects of life. The fourth objective is discussed in chapter 5, which contains the discussion of body theology to indicate how it can promote an inclusive understanding of sexuality. This chapter also discusses how body theology developed and the importance of the body in body theology. Chapter 6 includes conclusions and recommendations, such as that youth workers and church leaders need to recognise their own understanding of sexuality and the body, but that body theology can promote an inclusive understanding of sexuality if youth workers and church leaders are able to make a theological shift and use body theology as a theological lens.
AFRIKAANSE OPSOMMING: Hierdie studie ondersoek die waarde wat liggaamsteologie tot ʼn inklusiewe verstaan van seksualiteit tydens adolessensie kan byvoeg. Seksualiteit is deur verskillende tydperke verskillend verstaan, maar daar is selfs vandag nog nie werklik uitsluitsel van wat met die term seksualiteit bedoel word nie. Seksualiteit is ʼn moeilike term om te definieer en die verstaan daarvan speel ʼn belangrike rol in die wyse waarop mense mekaar hanteer. Die kerk was grootliks deur die verskillende tydperke óf stil oor seksualiteit óf het dit as ʼn sonde beskou, met die gevolg dat die kerk nie noodwendig as ʼn goeie hulpbron vir raad rakende seksuele sake beskou word nie. Adolessente gaan deur ʼn dramatiese tydperk waar alle ontwikkelingsprosesse, waarvan die seksuele ontwikkeling die prominentste is, gelyktydig plaasvind. Die seksuele ontwikkeling berei adolessente liggaamlik voor om voort te plant en in seksuele verhoudings te tree, maar kognitiewe en morele ontwikkeling vind ook plaas; hierdie twee prosesse is ondersteunend vir die adolessent om die seksuele ontwikkeling te kan verstaan en verwerk. Hierdie ontwikkelingsprosesse, tesame met die konteks waarin ʼn adolessent groot word, het ʼn invloed op die tipe morele waardestelsel wat adolessente saamstel, en wat bepaal hoe hulle optree. Soos reeds genoem, is die kerk nie noodwendig betrokke by hierdie gesprekke nie, en daarom stel hierdie studie voor dat kerke weer betrokke moet raak deur gebruik te maak van liggaamsteologie. Die navorsingsvraag kan soos volg geformuleer word: Watter bydrae kan liggaamsteologie maak tot die bevordering van ʼn inklusiewe verstaan van seksualiteit tydens adolessensie? Om die navorsingsvraag te beantwoord word die eerste doelstelling, om ʼn historiese oorsig oor die verstaan van seksualiteit te kry, om te sien hoe die verstaan van seksualiteit oor verskillende tydperke verander het, maar ook op sekere tye dieselfde verstaan van seksualiteit gehandaaf is, in hoofstuk 2 bespreek. Die tweede doelstelling word in hoofstuk 3 bespreek, waar die fokus op ʼn historiese oorsig van die verstaan van die liggaam val. Die historiese oorsig oor die verstaan van die liggaam word bespreek om ook te verstaan dat die liggaam baie keer in ʼn dubbelsinnige posisie gestaan het en dat dualismes deel gevorm het van die verstaan daarvan, maar dat dit ook verdere verstaan van die lewe beïnvloed het. In hoofstuk 4 word die derde doelstelling bespreek deur die sentrale rol van seksuele ontwikkeling tydens adolessensie te ondersoek om te verstaan watter belangrike rol seksuele ontwikkeling in die adolessent se lewe speel, maar ook dat dit ander aspekte van die lewe beïnvloed. Die vierde doelstelling word bespreek in hoofstuk 5, wat die bespreking van liggaamsteologie bevat om aan te dui hoe dit ʼn inklusiewe verstaan van seksualiteit kan bevorder. In hierdie hoofstuk word daar ook bespreek hoe liggaamsteologie ontstaan het en wat die belangrikheid van die liggaam in liggaamsteologie is. Hoofstuk 6 sluit die studie af met gevolgtrekkings en aanbevelings soos dat jeugwerkers en gemeenteleiers bewus moet word van hulle eie verstaan van seksualiteit en die liggaam, maar ook dat liggaamsteologie ʼn inklusiewe verstaan van seksualiteit kan bevorder, indien jeugwerkers en gemeenteleiers ʼn teologiese skuif maak en liggaamteologie as ʼn teologiese lens gebruik.

Ziel dieses Projektes war es, in Form einer Pilotstudie erste Erkenntnisse über die systematische Nutzung sozialer Netzwerke für den Kauf von Vertrauensgütern durch Privatpersonen zu gewinnen. Hierbei stehen insbesondere zwei Fragen im Vordergrund: (1) Werden soziale Netzwerke im Suchprozeß und bei der Kaufentscheidung von Vertrauensgütern genutzt, und wenn ja, welche Bedingungen beeinflussen das Ausmaß der Nutzung von sozialen Netzwerken? (2) Welche Effekte hat die Nutzung von sozialen Netzwerken im Hinblick auf Suchdauer und Kaufzufriedenheit?

Die Studie baut in Ihrer Zielsetzung auf den Erkenntnissen aus der im Jahre 1999 am Institut für Soziologie durchgeführten Studie mit dem Titel "Die soziale Einbettung von Konsumentenentscheidungen" auf. In dieser Studie wurden in Form einer Pilotstudie erste Erkenntnisse über die systematische Nutzung sozialer Netzwerke für den Kauf von Vertrauensgütern durch Privatpersonen gewonnen. In Anlehnung an das vorhergehende Forschungsprojekt standen die folgenden Fragen im Vordergrund: • Werden soziale Netzwerke im Suchprozeß und bei der Kaufentscheidung von Vertrauensgütern genutzt, und wenn ja, welche Bedingungen beeinflussen das Ausmaß der Nutzung von sozialen Netzwerken? • Welche Effekte hat die Nutzung von sozialen Netzwerken im Hinblick auf Suchdauer und Kaufzufriedenheit? In Abwandlung zur vorhergehenden Studie wurden die Bereiche "Wahl einer Versicherung" und "Wahl eines Zahnarztes" durch die Bereiche "Wahl einer Krankenversicherung" und "Wahl eines Hausarztes" ersetzt bzw. spezifiziert. Aufbauend auf den Erfahrungen aus dem vorhergehenden Projekt sollten hierbei noch zusätzliche Parameter der Netzwerkbeschaffenheit mit erhoben werden, um einen tieferen Einblick in den Zusammenhang zwischen Netzwerkstruktur und -nutzung bei Konsumentscheidungen zu gewinnen.

As a preliminary starting point for the present study, physical and mechanical properties of polypropylene nanocomposites (PPNCs) for samples received from Queen's University Belfast have been evaluated. Subsequently, polymer/clay nanocomposite material has been produced at Bradford. Mixing and processing routes have been explored, and mechanical properties for the different compounded samples have been studied. Clay intercalation structure has received particular attention to support the ultimate objective of optimising tensile and fracture behaviour of isotropic and die-drawn PPNCs. Solid-state molecular orientation has been introduced to PPNCs by the die-drawing process. Tensile stress-strain measurements with video-extensometry and tensile fracture of double edge-notched tensile specimens have been used to evaluate the Young's modulus at three different strain rates and the total work of fracture toughness at three different notch lengths. The polymer composite was analyzed by differential scanning calorimetry, thermogravimetric analysis, polarizing optical microscopy, wide angle x-ray diffraction, and transmission electron microscopy. 3% and 5% clay systems at various compatibilizer (PPMA) loadings were prepared by three different mixing routes for the isotropic sheets, produced by compression moulding, and tensile bars, produced by injection moulding process. Die-drawn oriented tensile bars were drawn to draw ratio of 2, 3 and 4. The results from the Queen's University Belfast samples showed a decrement in tensile strength at yield. This might be explained by poor bonding, which refers to poor dispersion. Voids that can be supported by intercalated PP/clay phases might be responsible for improvement of elongation at break. The use of PPMA and an intensive mixing regime with a two-step master batch process overcame the compatibility issue and achieved around 40% and 50% increase in modulus for 3% and 5% clay systems respectively. This improvement of the two systems was reduced after drawing to around 15% and 25% compared with drawn PP. The work of fracture is increased either by adding nanoclay or by drawing to low draw ratio, or both. At moderate and high draw ratios, PPNCs may undergo either an increase in the size of microvoids at low clay loading or coalescence of microvoids at high clay loading, eventually leading to an earlier failure than with neat PP. The adoption of PPMA loading using an appropriate mixing route and clay loading can create a balance between the PPMA stiffness effect and the degree of bonding between clay particles and isotropic or oriented polymer molecules. Spherulites size, d-spacing of silicate layers, and nanoparticles distribution of intercalated microtactoids with possible semi-exfoliated particles have been suggested to optimize the final PPNCs property.

Private Konsumenten stehen häufig vor dem Problem, Vertrauensgüter wie Gebrauchtwagen, Wohnungen oder Pauschalreisen erwerben zu wollen. Als Vertrauensgüter werden Produkte und Dienstleistungen bezeichnet, über deren relevante Eigenschaften der Käufer erst nach dem Kauf durch den Gebrauch Informationen erhält. Im Mittelpunkt dieses Projekts steht die These, dass sich das Vertrauensproblem zwischen Käufer und Verkäufer außer durch den Rückgriff auf formelle Regelungen, wie sie z.B. durch die Gesetzgebung zur Verfügung stehen, auch durch die Nutzung sozialer Netzwerke lösen läßt. Die Einbettung der wirtschaftlichen Transaktion in einen sozialen Kontext ermöglicht dem Käufer, auf Erfahrungen Dritter mit diesem Produkt und/oder diesem Verkäufer zurückzugreifen. Zudem muß der Verkäufer im Falle falscher Versprechungen damit rechnen, einen schlechten Ruf zu erhalten. Die Wirksamkeit dieser Mechanismen ist unter anderem abhängig von den Eigenschaften des sozialen Netzwerkes wie Größe, Dichte oder Heterogenität. Handlungs- und netzwerktheoretische Konzepte erlauben die Ausarbeitung entsprechender Hypothesen, die im Rahmen einer regional begrenzten Pilotstudie getestet wurden. Die ersten Analysen mit den vorliegenden Daten bestätigen vor allem die Bedeutung von persönlichen Netzwerken bei der Wohnungssuche, der Auswahl einer Versicherung sowie der Suche nach einem Zahnarzt oder einem Reisebüro für Pauschalreisen. So geben beispielsweise 73,1% der Befragten an, dass Freunde, Bekannte oder die eigene Familie hilfreich oder sogar sehr hilfreich bei der Suche nach einer Wohnung waren. 45,2% gaben an, vor ihrem letzten Versicherungsabschluß als erstes Rat innerhalb ihres sozialen Netzwerkes gesucht zu haben, während sich nur 24,7% als erstes direkt an die Versicherungsgesellschaft wandten. Das Vorhandensein von Netzwerken, die aufgrund theoretischer Erwägungen für die Suche nach einem Vertrauensgut günstige Eigenschaften aufweisen, erleichtert oder verkürzt die Suche jedoch nicht generell. Für die Frage nach den Effekten der Nutzung von persönlichen Netzwerken für die Suche und Auswahl von Vertrauensgüter sind detailliertere Auswertungen sowie eine umfangreichere Datenbasis notwendig.

Legislation has been proposed in Kentucky that would authorize city legislative bodies to levy a tax on restaurant meals of no more than 3%, regardless of the size of the city. The bill has garnered attention from Kentucky Travel Industry Association, the Kentucky Restaurant Association, and local tourism and restaurant organizations and associations that oppose the tax. The Kentucky League of Cities, an organization that represents the interests of city governments, supports the tax. The purpose of this research was to examine how a change in the tax rate on restaurant meals would affect restaurant demand. Effects of changes in restaurant demand were tested using the following independent variables: type of restaurant, menu offering, frequency, expense, and location. Self-administered online surveys were distributed to adult residents in Kentucky, which yielded a sample size of 1,263 individuals. Paired sample t test was applied to make comparison between scenario 1 (current) and scenario 2 (3%) and scenario 1 (current) and scenario 3 (JND). Findings showed that demand patterns in each class of city would be affected by increases in taxes and prices.

The main contribution of this thesis to knowledge, is its analysis of the nature and behaviour of the export sector of the Icelandic fishing industry. The thesis identifies the current structure of the export sector and focuses on the main characteristics of export behaviour of the exporting firms. The thesis starts by providing an insight into the fundamental role of exporting for economic performance in Iceland, and the distinctive role of the fishing industry in generating export income. This is followed by a descriptive analysis of the historical development of the three defined sectors of the fishing industry, i.e. the fishery, processing, and export sectors. A review of the literature on export behaviour of firms, is undertaken in the second part of the thesis, to provide a theoretical background to the empirical investigation, introduced in the third part. The third part contains a qualitative presentation of the primary information collected in the research, together with results from a questionnaire survey, which followed up some of the findings recorded in the qualitative analysis. This section identifies the main types of firm in the export sector, and analysis is made of the export behaviour of different groups of firms in the sector. Consideration is given to factors which encouraged the entry of new firms into exporting, especially during the 1980s, the firms' process of internationalisation, and factors identified by exporters as obstacles in exporting. The study also considers the firms' different objectives in exporting, and the main characteristics of their export marketing strategies and management.

Thesis (PhD)--Stellenbosch University, 2003.
ENGLISH ABSTRACT: The sungazer, Cordylus giganteus, is an endangered lizard species belonging to the family Cordylidae. It has been speculated that the function of semiochemical communication is performed by two types of skin glands, the femoral glands and the generation glands, which are also found in this family of lizards. Other skin glands and also the cloacal glands are further possible sources of semiochemicals. The investigation of these potential sources of chemical messages in C. giganteus, served as a starting point towards a better understanding of the chemical communication of lizard species belonging to the family Cordylidae. In continuation of this study the femoral gland secretion of the Cape girdled lizard, C. cordylus, was also investigated. Gas chromatography, low resolution GC-MS, GC-HR-MS, MO-TMS derivatisation and retention time comparison were used as analytical techniques in the chemical characterization of the femoral and generation gland secretions of C. giganteus and the femoral gland secretion of C. cordylus. Some compounds were not identified because of their low concentration in the secretions and/or mass spectra could not be obtained for pure compounds because of co-elution with other compounds. Compounds identified in the femoral gland secretion include the following: Carboxylic acids - saturated and unsaturated Alcohols Ketones Aldehydes - saturated and unsaturated Esters - saturated and unsaturated Hydrocarbons - saturated and unsaturated Nitriles Amides - saturated and unsaturated y-Lactones Squalene u-Tocopherol Steroids Quantitative analysis of the femoral and generation gland secretions of a number of sungazers indicated distinct differences between the secretions of males and females (in the case of the femoral gland secretions), but no apparent trend could be found in the differences between the femoral and generation gland secretions of individual lizards of the same gender. Qualitative seasonal differences were however observed in the femoral gland secretions of all individuals of C giganteus.
AFRIKAANSE OPSOMMING: Die ouvolk, Cordylus giganteus, is 'n bedreigde akkedisspesie van die familie Cordilidae. Daar is gespekuleer dat twee soorte velkliere wat by hierdie familie akkedisse voorkom, naamlik die femorale- en generasiekliere, betrokke is by semiochemiese kommunikasie van hierdie diere. Ander velkliere, asook die kliere in die akkedisse se kloaka, is ook potensiele bronne van semiochemiese verbindings. Die bestudering van hierdie potensiele bronne van chemiese boodskappe by C. giganteus is as 'n beginpunt gebruik om die semiochemiese kommunikasie van die akkedisse van die familie Cordilidae beter te verstaan. Ter uitbreiding van hierdie studie is die femorale klierafskeiding van die Kaapse gordelakkedis, C. cordylus, ook ondersoek. Die femorale en generasieklierafskeidings van C. giganteus en die femorale klierafskeidings van C. cordylus is chemies gekarakteriseer deur van analitiese tegnieke, naamlik gaschromatografie, lae resolusie GC-MS, GC-HR-MS, MO- TMS derivatisering en retensietydvergelyking, gebruik te maak. Talle verbindings is nie geidentifiseer nie omdat hulle in 'n baie lae konsentrasie in die afskeidings voorkom, en/of saam met ander komponente elueer, wat veroorsaak dat daar nie massaspektra vir hierdie suiwer komponente verkry kon word nie. Verbindingstipes wat in die afskeidings voorkom, sluit die volgende in: Karboksielsure - versadig en onversadig Alkohole Ketone Aldehiede - versadig en onversadig Esters - versadig en onversadig Koolwaterstowwe - versadig en onversadig Nitriele Amiede - versadig en onversadig y-Laktone Skwaleen a-Tocopherol Steroiede Kwantitatiewe analises van die femorale en generasieklierafskeidings van verskeie ouvolk akkedisse het getoon dat daar duidelike kwantitatiewe verskille tussen die afskeidings van mannetjies en wyfies is (in die geval van die femorale klierafskeidings), maar dat daar geen duidelike patroon in die verskille tussen die femorale en generasieklierafskeidings van individuele akkedisse van dieselfde geslag is rue. Daar is kwalitatiewe seisoenale verskille tussen die femorale klierafskeidings van individue van C. giganteus gevind.

Serotonin (5-HT) nimmt eine wichtige Rolle in der Regulation von Nahrungsaufnahme ein. Erhöhte 5-HT-Freisetzung hemmt die Nahrungsaufnahme. Der 5-HT1A-Rezeptor liegt sowohl somatodendritisch als auch postsynaptisch vor. Seine Stimulation mit 8-OH-DPAT vermindert die 5-HT-Freisetzung. Die in-vivo-Mikrodialyse ermöglichte uns eine kontinuierliche Messung von extrazellulärem 5-HT im lateralen Hypothalamus an der frei beweglichen Ratte. Unsere Ergebnisse zeigen einen Abfall der 5-HT-Freisetzung bei satten Ratten, nicht jedoch wenn diesen nach Substanzgabe Futter angeboten wurde. Bei hungrigen Ratten war nach Substanzgabe keine signifikante Veränderung in der 5-HT-Freisetzung zu messen. Zusammenfassend wird mit der vorliegenden Studie erstmals die Wirkung von 8-OH-DPAT auf die 5-HT-Freisetzung im LHA in Abhängigkeit von unterschiedlichen Motivationszuständen in Verbindung mit Nahrungsaufnahme gezeigt.
Serotonin (5-HT) is an important mediator of satiety. Increase of 5-HT release inhibits food intake. 8-OH-DPAT, an agonist at the somatodendritic 5-HT1A autoreceptor, reduces serotonergic activity and induces food intake. With the technique of in vivo microdialysis we were able to measure continuously extracellular 5-HT in the lateral hypothalamic area (LHA) in freely moving rats under different feeding conditions. The present results show a decrease of 5-HT release in freely feeding rats after administration of 8-OH-DPAT. This effect was not obtained when offering food after drug application. In contrast, no significant effect in 5-HT release after application of 8-OH-DPAT in food deprived rats was measured. In summery this study demonstrates the effect of 8-OH-DPAT on the 5-HT release in LHA of freely moving rat depending on the different feeding conditions.

The Whole thesis is in Afrikaans: Epilepsy is a phenomenon that can manifest in a variety of ways, which differ mainly in severity, appearance, aetiology, effect and control thereof. In this study a lack of knowledge and education about epilepsy is pointed out as a factor that was neglected over the years. It is of utmost importance to distinguish between three main categories of epilepsy as all three types have a restraining effect that may leave any learner vulnerable. The popular belief about the concept epilepsy until recently did not recognize the type of epilepsy where a disturbance in consciousness or relapse in consciousness only occurred as in the case with elementary partial attacks (temporal and frontal lobe epilepsy). Ignorance about temporal and frontal lobe epilepsy, as well as the fact that the physical symptoms of this type of epilepsy are very subtle in nature, may be the cause why acceptance of this condition has been slow or undervalued. In reality learners with lobe epilepsy are not regarded as disabled and should such a learner not be diagnosed and not receive the correct treatment, he/she will not be able to function optimally. The researcher has made a study of epilepsy as well as the physical, cognitive, emotional, social, self image impact on the learner in family and school context. The impact of epilepsy on the primary school learner was studied from a gestalt point of view. In this study the researcher employed both a quantitative and qualitative research approach. It was therefore fitting to formulate a research question and a hypothesis. The research question formulated for this study is as follows: What is the knowledge basis of teachers regarding learners with lobe epilepsy? The empirical study indicated that the researcher could provide an answer to the research question by way of semi-structured interviews that indicated that the knowledge basis of the teachers was not sufficient to identify learners with this phenomena. The researcher determined through these interviews that teachers experienced a need to extend their knowledge about temporal and frontal lobe epilepsy. The hypothesis formulated for this study is as follows: Should information and clear guidelines regarding the identification of a learner with lobe epilepsy be offered to teachers, the learner with lobe epilepsy would be identified timeously in the school system. The researcher did a pre-test on the knowledge levels on lobe epilepsy among teachers by way of questionnaires. The pre-test was followed by a structured information session after which an after-test was done by way of questionnaires to determine the change in the teachers’ knowledge basis. The empirical study showed that the teachers’ knowledge basis increased due to the information session offered to them. After this study the teachers could identify learners and refer them for diagnosis and treatment as a result of an increased knowledge basis about this phenomena. The study was followed up by guidelines offered to the teachers on identifying the primary school learner with temporal and frontal lobe epilepsy.
Thesis (DPhil (Social Work))--University of Pretoria, 2005.
Social Work and Criminology
unrestricted

Ziel dieses Projektes war es, in Form einer Pilotstudie erste Erkenntnisse über die systematische Nutzung sozialer Netzwerke für den Kauf von Vertrauensgütern durch Privatpersonen zu gewinnen. Hierbei stehen insbesondere zwei Fragen im Vordergrund: (1) Werden soziale Netzwerke im Suchprozeß und bei der Kaufentscheidung von Vertrauensgütern genutzt, und wenn ja, welche Bedingungen beeinflussen das Ausmaß der Nutzung von sozialen Netzwerken? (2) Welche Effekte hat die Nutzung von sozialen Netzwerken im Hinblick auf Suchdauer und Kaufzufriedenheit?:Kurzbeschreibung; Feldarbeit; Datenbeschreibung; Anlage

Die vorliegende Dissertation beschäftigte sich theoretisch und empirisch mit moralischer Sensitivität, der Fähigkeit zu erkennen, ob Handlungen das Wohlergehen anderer Lebewesen beeinflussen. Im Theorieteil wurden dazu die einschlägigen theoretischen Ansätze gesichtet und in einer neuen integrativen Definition verdichtet. Aus der theoretischen Aufarbeitung der Konzepte und bisherigen empirischen Befunde folgte, dass verschiedene Persönlichkeitsmerkmale existieren, die maßgeblich determinieren, ob und wie stark ein Individuum moralisch sensitiv ist. Zu diesen Determinanten moralischer Sensitivität gehören folgende Persönlichkeitsmerkmale: Empathie, moralische Achtsamkeit, moralische Identität und Ungerechtigkeitssensibilität. Im empirischen Teil der Arbeit wurden die Zusammenhänge dieser Persönlichkeitsmerkmale mit moralischem Entscheiden und Handeln untersucht, sowie verschiedene studienspezifische Hypothesen und Fragestellungen beleuchtet. Einzelne Aspekte der empirischen Arbeit wurden schließlich in einer interkulturellen Studie auf ihre kulturübergreifende Generalisierbarkeit geprüft. Die Dissertationsschrift schließt mit einer umfassenden Diskussion der empirischen Ergebnisse und gibt praktische Handlungsempfehlungen. Unternehmen und andere Organisationen können die in der vorliegenden Dissertation gewonnenen Erkenntnisse nutzen, um ihr Human Ressource Management hinsichtlich der Auswahl und Förderung ethisch-kompetenter Fach- und Führungskräfte zu optimieren.
The present dissertation theoretically and empirically investigated the concept of moral sensitivity – the ability to recognize whether actions influence the well-being of other living beings. In the theoretical part, the relevant theoretical approaches were reviewed and condensed in a new integrative definition. The review of the theoretical accounts of moral sensitivity and the empirical findings revealed that various personality traits exist that decisively determine whether and how strongly an individual is morally sensitive. These determinants of moral sensitivity include the following personality traits: empathy, moral attentiveness, moral identity, and justice sensitivity. In the empirical part of the work, the relationships of these personality traits with moral decision-making and action and various study-specific hypotheses were examined. The cross-cultural generalizability of some empirical findings of the dissertation was finally examined in an intercultural study. The dissertation concludes with a comprehensive discussion of the empirical results and gives practical recommendations for organizations. Companies and other organizations can use the knowledge gained in this dissertation to optimize their human resource management in terms of selection and promotion of ethical competent employees.

Children often need to be placed in substitute care as the result of inadequate carers / parents who abuse and mistreat them. Children in substitute care find it very difficult to adapt to mo re positive circumstances and therefore display difficult behaviour. T he substitute carers therefore experience difficulty in handling these children, which often results in the children needing to be placed again. It seems as if the way in which a child attaches to the primary caregiver in their early years can determine how this child will function later in life. T he secure attachment process is the foundation on which further positive relationships with other people and with the child him/herself are built. There are clear similarities between behavioural and emotional problems and early mother separation. It appears that there is a lack of knowledge and understanding regarding the origin of these problems as well as with regard to correct approaches to such problems. The substitute carers need to be supported in order to understand t he children, and therefore it is neccessary to suppor the carers in ways to build attachments between the carer and child. Goals: The primary aim of this study is to determine what kind of knowledge and equipment the substitute carers need in order to provide in the necessary attachment needs of the children in their care. Method: Research was conducted by means of the qualitative method. Information was gathered through the semi-structured interview method, questionnaires were sent to carers, and observations were made during the intervening period. An independent professional person was used to perform t he assessments and to verify the results of the assessment and research. Triangulation of the research was done. Results: Results of the research were as follows: Although the research follows a qualitative approach, hypotheses are formulated which can be used for further dissectation regarding the provision in attachment needs of middle childhood phase children who are in substitute care
Thesis (M.A. (MW))--North-West University, Potchefstroom Campus, 2009.

Es scheint in den letzten Jahren eine deutliche Veränderung in der Art der Kommunikation mit den sogenannten Neuen Kommunikationstechnologien stattgefunden zu haben, und zwar im Längsschnitt, also etwa über die letzten 10, 15 Jahre, wie auch zwischen den sich aus heutiger Sicht herausentwickelt habenden Nutzergruppen. Quantitative Erhebungen, am ausgeprägtesten die regelmäßig unternommenen und von den Medien wiedergegebenen "Internetumfragen", ebnen solche Veränderungen naturgemäß vollständig ein. Auch die vorhandenen qualitativen Arbeiten reflektieren solche Veränderungen meist nicht, da zeitliche Dimensionen üblicherweise in den Fragestellungen fehlen. Der Beitrag versucht eine Skizze dieser Entwicklungen, möchte einige Mißverständnisse im Zusammenhang mit neuer "Elektronischer Kommunikation" korrigieren helfen und kommunikationsökonomische Aspekte beisteuern.

A healthy and positive relationship between educators and learners is an important aspect in the establishment and sustainability of a nurturing and enabling school environment. However, research pertaining to South African schools shows that schools currently face many challenges that threaten relationships in schools and adversely affect the general well-being of the individuals concerned. The situation is problematic in every school context, but even more so in schools where risk factors are present in a concentrated form, as is the case in schools of skills. The researcher has been involved as a school counsellor at various schools of skills in the Western Cape for the past three years and has noticed that schools of skills are often exposed to various risk factors that influence the daily interaction between educators and learners and also impede the fostering of a healthy relationship between educators and learners. It is therefore logical that the relationship between educators and learners in schools of skills is influenced by the particular circumstances and that the relevant risk factors could be contributing to the current situation in schools of skills. Limited research about the relationship between educators and learners in the context of schools of skills impedes the situation even more. This research study aims to make a contribution to the solution of the identified problem by investigating ways in which the relationships between educators and learners can be improved within the context of schools of skills in the Western Cape. A literature study and empirical investigation were undertaken to achieve a better understanding of the relationship between educators and learners in schools of skills and the way the respective parties experience it (the relationship). Therefore, the nature of the structure of this research study is qualitative phenomenological because it incorporates an investigation into the social relationships that connect educators and learners. The research study was done in four schools of skills in the Western Cape that is representative of the different settlement contexts in South Africa, namely urban, semi-urban and rural. The participants in the four various schools include educators (n=42) and learners (n=122). The collection of data took place in four phases and the following qualitative data collection methods were used: qualitative open-ended questionnaires and semi-structured individual interviews for educators as well as collages and semi-structured focus group interviews for learners. Thematic analysis of the respective data sets showed that the relationships between educators and learners can be improved by considering the contextual challenges both educators and learners are confronted with. Besides considering the contextual challenges it is also important to create spaces where relationships can be improved and learners can feel safe. This seems to be mainly the responsibility of the educators and can be done by setting clear boundaries and upholding healthy discipline. It was further demonstrated that the relationship between educators and learners in schools of skills can be improved by acting towards each other in such a way that mutual respect, mutual trust, the provision of care and support and open communication can be established as relationship-improving interaction patterns. In the light of the study’s findings, specific guidelines are provided to the educator at the school of skills and clear recommendations are made to the Department of Education with the aim of improving classroom relationships in schools of skills. In conclusion, recommendations are also made about further research to improve relationships between educators and learners in schools of skills.
Thesis (MA (Psychology))--North-West University, Potchefstroom Campus, 2013.

Thesis (MA)--University of Stellenbosch, 2002.
ENGLISH ABSTRACT: Adolescents belonging to lower socio economic groups, seem to be at risk for teenage pregnancies as well as the contraction of sexually transmitted diseases and HIV/AIDS. It is therefore important to study the sexual behaviour of these adolescents. This study focussed on the sexual behaviour of coloured and black female adolescents from working class communities. The respondents consisted of all the coloured and black female adolescents in a traditional coloured and a traditional black school in a semi-rural area. A self-administrative questionnaire was used. The questionnaire focussed on biographical details, the language adolescents use when they talk about sex as well as their sexual and contraceptive behaviour. The goals of the study were to describe the sexual behaviour of the black adolescents and to compare the sexual behaviour of the coloured and the black respondents. A quantitative methodology was used to examine the black respondents' range of sexual behaviour, communication about sex, sexual force and molestation as well as high risk sexual behaviour. According to the results a high percentage of black adolescents used Western and medical terms when they talk about sex. The sexually active black adolescents had coitus at an early age which could have implications for the incidence of teenage pregnancies and HIV/AIDS. A large percentage of the black adolescents indicated that they did not masturbate. Most of the black adolescents also indicated that they did not talk about sex with other people. A small percentage of the black adolescents reported that they were sexually molested or raped. A comparison with the coloured adolescents indicated that: more of the black adolescents reported that they had had coitus; more black adolescents reported pregnancies, more black respondents reported that they masturbated and fewer black adolescents reported that they smoked and used alcohol.
AFRIKAANSE OPSOMMING: Adolessente wat aan laer sosio-ekonomtese graepe behaart, blyk 'n hoë risikagroep te wees vir tienerswangerskappe sawel as vir seksueel-aardraagbare siektes en MIV/VIGS. deel vorm. Dit is dus belangrik dat hierdie adalessente se seksuele gedrag nagevars ward. Hierdie studie het gefakus ap die seksuele gedrag van bruin en swart vroulike adolessente afkamstig uit werkersklas gemeenskappe. Die respandente het bestaan uit alle vroulike adolessente by 'n tradisianele bruin skaal en 'n tradisionele swart skaal in 'n semilandelike area. 'n Self-geadministreerde vraelys wat gefakus het ap biagrafiese gegewens, die taal wat adolessente gebruik wanneer hulle van seks praat asook seksuele en kantraseptiewe gedrag is in die studie gebruik. Die dael van die studie is eerstens om 'n beskrywing te bied van die swart adolessente se seksuele gedrag en tweedens om die seksuele gedrag van die bruin en swart adolessente met mekaar te vergelyk. "n Kwantitatiewe metadalagie is gebruik om die spektrum van seksuele gedrag, kommunikasie aar seks, seksuele dwang en malestering asook haë risiko seksuele gedrag van die swart respandente te ondersoek, Die resultate het daarop gedui dat "n graot persentasie van die swart adolessente gebruik maak van Westerse en mediese terme wanneer hulle van seks praat. Die aanvang van koïtus vir die seksueel aktiewe swart adolessente was ap "n vroeë ouderdom , wat implikasies kan hê vir die voorkoms van tienerswangerskappe en MIV/VIGS. 'n Graat persentasie van die swart adolessente het gerapparteer dat hulle nie masturbeer nie. Dit het verder geblyk dat hierdie graep swart adolessente selde verbaal aar seks kammunikeer met ander persone. "n Klein persentasie van die swart adolessente het qerapporteer dat hulle seksueel gemalesteer af verkrag is. "n Vergelyking met die bruin adolessente het aangedui dat meer swart adolessente kaitus gehad het, meer swart adalessente swangerskappe gerapparteer het, meer swart adalessente aangedui het dat hulle gemasturbeer het en dat minder swart adolessente raak en alkahalgebruik gerapparteer het.

It has been hypothesized that dietary differences in bone consumption exist between the extinct Pleistocene dire wolf (Canis dirus) and the modern gray wolf (C. lupus). Here dental microwear texture analysis of the m2 is used to test the hypothesized dietary behavior of C. dirus. If the m2 does distinguish dietary tendencies and dire wolves were heavy bone consumers, then the microwear signals of C. dirus should be similar to extant duraphageous canids. Microwear texture analysis of C. dirus was compared with that of C. lupus, coyote (C. latrans), and African wild dog (Lycaon pictus) to assess the degrees of bone consumption. An overall lack in statistically significant variables suggests little difference between the dietary tendencies between C. dirus and C. lupus. The dire wolf did not closely align with the duraphageous L. pictus, which calls into question the hypothesis of heavy carcass utilization during the Pleistocene.

Biomanipulation im Sinne einer top-down Steuerung des Nahrungsnetzes wurde in Standgewässern intensiv erforscht und wird als Mittel zur Verbesserung der Wasserqualität bzw. Verringerung der Eutrophierungserscheinungen eingesetzt. Ebenso könnte die Idee der Biomanipulation genutzt werden, um die Eutrophierung in kleinen Fließgewässern zu verringern. Eine Förderung benthischer herbivorer Schlüsselorganismen (z.B. Eintagsfliegenlarven) durch die Reduzierung des Fischfraßdruckes könnte helfen, Algenmassenentwicklungen zu vermeiden. Studien zur Biomanipulation von Nahrungsnetzen in Standgewässern zeigten allerdings eine zunehmende Entwicklung von planktischen invertebraten Räubern bei Abwesenheit planktivorer Fische. Die Bedeutung des Fraßdruckes invertebrater Räuber in fischfreien Fließgewässernahrungsnetzen ist dagegen noch unbekannt. Aufgrund von letalen und subletalen Fischeffekten könnte die Konsumtion räuberischer Invertebraten bei Fischabwesenheit so stark gefördert werden, dass das Ziel der Biomanipulation verfehlt wird. Invertebrate Räuber haben insgesamt einen relativ hohen Anteil an der Biomasse der Benthosgemeinschaft in Fließgewässernahrungsnetzen. Sie könnten somit potentiell einen ähnlichen Fraßdruck wie vertebrate Räuber (z.B. benthivore Fische) auf die unteren trophischen Ebenen ausüben. Auch der Anteil der Omnivorie ist in Fließgewässernahrungsnetzen hoch. Ziel dieser Arbeit war es deshalb, die Bedeutung invertebrater Prädation im Nahrungsnetz eines kleinen Fließgewässers (Gauernitzbach) unter Berücksichtigung der obligaten Räuber sowie des räuberischen Potentials Omnivorer abzuschätzen. Außerdem wurde der Einfluss benthivorer Fische auf die Populationsentwicklung und das Ernährungsverhalten der wichtigsten invertebraten Räuber und Omnivoren untersucht. Dazu wurde ein Bachabschnitt, der mit benthivoren Fischen (Gobio gobio, Barbatula barbatula) besetzt war, mit einem fischfreien Abschnitt über zwei Jahre verglichen. Nach der Identifizierung wichtiger Räuber- und Omnivorenarten anhand ihrer Biomasse und ihrer trophischen Positionen mittels Isotopenanalyse wurde ihr Gesamtfraßdruck abgeschätzt. Invertebrate Prädatoren im Nahrungsnetz des Gauernitzbaches waren Rhyacophila fasciata und Plectrocnemia conspersa (Trichoptera), Isoperla grammatica (Plecoptera) sowie Dugesia gonocephala (Turbellaria). Wichtige Omnivore aufgrund ihrer hohen Biomassen waren Gammarus pulex (Amphipoda) und Hydropsyche spp. (Trichoptera). Anhand eines Mischungsmodells (ISOSOURCE), das auf der Basis der stabilen Isotopensignaturen d13C und d15N die einzelnen Ressourcenanteile einer gemischten Signatur berechnet, konnte das ausgeprägte räuberische Potential der Omnivoren gezeigt werden, da sie einen hohen tierischen Anteil in der Nahrung aufwiesen (20-90 %). Im Nahrungsnetz des Gauernitzbaches waren Omnivore als Räuber damit ebenso bedeutsam wie obligat räuberische Invertebrate. Der Gesamtfraßdruck der invertebraten Räuber und Omnivoren auf die Beuteorganismen (bis 16 g TM m-2 a-1) in der Fischstrecke war höher als der Fraßdruck der benthivoren Fische (~3 g TM m-2 a-1). Dieser Unterschied lag hauptsächlich in höheren täglichen Konsumtionsraten bei ähnlich hohen Biomassen der Invertebraten begründet. Durch die Analyse der stabilen Isotope von Kohlenstoff und Stickstoff konnten die trophischen Beziehungen im Nahrungsnetz des Gauernitzbaches identifiziert werden. Dabei stellten allochthone Kohlenstoffquellen im Frühjahr und Herbst die bedeutendste Ressource für die Primärkonsumenten dar, während autochthone Ressourcen nur im Frühjahr für wenige Herbivore relevant waren. Dies spiegelte sich ebenso in der Nahrung der Omnivoren wider, die neben Organismen hauptsächlich Detritus nutzten. Ebenso zeigten die invertebraten Räuber eine deutliche Abhängigkeit vom allochthonen Kohlenstoff über die Nutzung der Primärkonsumenten. Letale Effekte der Fische auf die räuberischen und omnivoren Populationen im Gauernitzbach fanden hauptsächlich in Abhängigkeit von den bewohnten Habitaten statt. Die Pool-Arten (P. conspersa, D. gonocephala, G. pulex) entwickelten geringere Biomassen in der Fischstrecke, während die Biomassen riffle-bewohnender Invertebraten (R. fasciata, I. grammatica, Hydropsyche spp.) nicht deutlich reduziert wurden. Dabei waren allerdings meist hohe Biomassen in der Fischstrecke weniger stark ausgeprägt als in der fischfreien Strecke. Die Adulten der untersuchten Arten wurden oft stärker letal beeinflusst als die Juvenilstadien. So war die Emergenzproduktion der räuberischen Köcherfliegen und die Abundanz großer und eiertragender Weibchen von G. pulex in der Fischstrecke deutlich verringert. Subletale Effekte der Fische traten im Gauernitzbach in Abhängigkeit von den Ernährungstypen auf. Während die adulten räuberischen Köcherfliegenarten R. fasciata und P. conspersa keine negative Beeinflussung der Fitness und Größe zeigten, emergierte die omnivore Köcherfliege H. instabilis in der Fischstrecke kleiner als in der fischfreien. Außerdem unterschieden sich die Antworten der omnivoren Arten vermutlich aufgrund ihrer unterschiedlichen Lebenszyklen. G. pulex zeigte als ausschließlich aquatisch lebende Art keine subletalen Kosten (unveränderte Fitness) bei Fischanwesenheit wie dies für die omnivore merolimnische Insektenart H. instabilis beobachtet wurde. Die mittlere Fitness der Populationen (gemessen an der Eiproduktion pro Zeit- und Flächeneinheit) war für alle untersuchten invertebraten Räuber und Omnivoren bei Fischanwesenheit deutlich geringer als in der fischfreien Strecke. Für die Räuber (R. fasciata, P. conspersa) und G. pulex waren vermutlich letale Fischeffekte für den geringen Reproduktionserfolg verantwortlich. Dagegen wurde die Fitness der Population von H. instabilis durch die Kombination aus der geringeren individuellen Körpergröße (subletal) und den schwachen letalen Effekten auf die Emergenz reduziert. Der Einfluss der Fische auf die räuberischen Larven von R. fasciata und P. conspersa resultierte in einem Wechsel der Beutezusammensetzung, nicht in der Reduzierung der täglichen Fraßaktivität. Dies war vermutlich auf eine Aktivitätsänderung des Räubers R. fasciata bzw. auf die veränderte Beuteverfügbarkeit für P. conspersa unter Fischeinfluss zurückzuführen. Eine grundsätzliche Verringerung der Fraßaktivität oder der tierischen Anteile in der Nahrung der omnivoren Arten unter dem Einfluss benthivorer Fische wurde nicht festgestellt. Dagegen änderten sich die Relationen der Ressourcen Omnivorer zueinander, so konnte in der fischfreien Strecke eine flexiblere Ressourcennutzung nachgewiesen werden. Die jährliche Gesamtkonsumtion der räuberischen und omnivoren Invertebraten wurde durch die Anwesenheit der benthivoren Fische um 20-50 % reduziert, wofür hauptsächlich fischinduzierte Biomasseänderungen verantwortlich waren. In der fischfreien Strecke konnte dagegen die erhöhte Konsumtion der Invertebraten den fehlenden Fischfraßdruck mehr als kompensieren. Allerdings änderte sich die beutespezifische Konsumtion der Räuber in der fischfreien Strecke durch den verhaltensinduzierten Wechsel in der Beutezusammensetzung. Damit fand ein erhöhter Fraßdruck auf detritusfressende Arten (z.B. Diptera) statt, während die vermuteten Schlüsselarten einer potentiellen Biomanipulation (grazende Eintagsfliegen) in der fischfreien Strecke relativ unbeeinflusst blieben. Da die invertebrate Prädation in Fließgewässern sehr bedeutend sein kann, ist Biomanipulation nur unter Berücksichtigung aller Populationen räuberischer Invertebraten möglich. Nur durch Einstellung einer optimalen (relativ hohen) Biomasse geeigneter benthivorer Fischarten kann eine ausreichende Hemmung der invertebraten Räuber erreicht werden, so dass grazende Arten indirekt profitieren
Biomanipulation (top-down control of the food webs) in lakes was intensively studied and can today be regarded as an important tool for improvement of the water quality and eutrophication. Similarly, the idea of biomanipulation can be used to reduce eutrophication phenomena in streams. The enhancement of benthic herbivorous key species (e.g. mayflies) by reduction of fish predation pressure could prevent exploding benthic algae biomass. Studies dealing with trophic cascades in lakes suggested that biomass of planktic invertebrate predators is increasing in the absence of planktivorous fish. But until now the importance of invertebrate predation pressure in fishless stream food webs is hardly known. Due to lethal and sublethal fish effects the consumption of predatory invertebrates could be enhanced by the absence of fish to such an extent that biomanipulation could be off target. In general, the proportion of invertebrate predators to the biomass of the benthic community in stream food webs is relatively high. Therefore, invertebrate predation on benthic prey can be as important as vertebrate predation (e.g. by benthivorous fish). Furthermore, omnivory occurs frequently in streams. Therefore, the aim of this thesis was to assess the importance of invertebrate predation in a food web of a small stream (Gauernitzbach) including the obligatory predators as well as the predatory potential of omnivores. Furthermore, the impact of benthivorous fish on population dynamics and feeding behaviour of the most important predators and omnivores was studied. Therefore, a reach stocked with benthivorous fish (Gobio gobio, Barbatula barbatula) was compared with an upstream fishless reach over a two-year period. After identification of important predators and omnivores based on their biomass and trophic position by stable isotope analyses their total consumption was estimated. Rhyacophila fasciata and Plectrocnemia conspersa (Trichoptera), Isoperla grammatica (Plecoptera) as well as Dugesia gonocephala (Turbellaria) were the invertebrate predators in the food web of Gauernitzbach. Because of their high biomasses the most important omnivores were Gammarus pulex (Amphipoda) and Hydropsyche spp. (Trichoptera). Using a mixing model (ISOSOURCE) that estimates the proportions of single resources on a mixed signature on the basis of the stable 13C and 15N isotopes, the predatory potential of both omnivores was pronounced by a high animal food proportion (20-90%). In this stream food web the predation impact of omnivores was comparable to this of obligatory predacous invertebrates. The total invertebrate predation pressure (up to 16 g TM m-2 a-1) in the fish reach was higher than the vertebrate predation pressure (~3 g TM m-2 a-1) mainly caused by the higher daily consumption rates and similar biomass compared to fish. Using stable isotope analyses of carbon and nitrogen the trophic pathways in the food web of Gauernitzbach could be identified. The most important resources for primary consumers in spring and autumn were allochthonous carbon sources. Autochtnonous carbon sources were only utilized by a few herbivores in spring. This was also reflected in the food of omnivores which assimilated mainly detritus beside animal material. Similarly, the predators depended distinctly on the allochthonous pathway by feeding primary consumers. Lethal fish effects on the predatory and omnivorous invertebrate populations were mainly depended on their preferred habitats. Pool-dwelling species (P. conspersa, D. gonocephala, G. pulex) showed decreased biomass in the presence of fish. Contrary, the biomass of riffle-dwelling invertebrates (R. fasciata, I. grammatica, Hydropsyche spp.) was not significantly reduced in the fish reach. Thereby, the highest biomass values in the fish reach could not reach the same level as in the fishless reach. Adults of the investigated species were influenced more lethal than the young stages. Hence, the emergence production of the predatory caddisflies and the abundance of the biggest and gravid females of G. pulex were reduced in the fish reach. Sublethal fish effects existed in dependence on the feeding groups of the invertebrates in Gauernitzbach. Whereas the adult predatory caddisflies R. fasciata and P. conspersa did not show disadvantages in fitness and size, the omnivorous caddisfly H. instabilis emerged with smaller size in the fish reach than in the fishless reach. Different responses of both omnivorous species were observed because of their different life cycles. The exclusively aquatic living G. pulex was not influenced sublethal by fish as the merolimnic insect species H. instabilis. The average fitness of population (measured as egg production per unit time and space) of the studied invertebrate predators and omnivores was distinctly reduced in the fish reach compared to the fishless reach. Probably, lethal fish effects were mainly responsible for the low reproductive success of the predatory species (R. fasciata, P. conspersa) and G. pulex. In contrast, the reduction of population fitness of H. instabilis was caused by the reduced individual adult size (sublethal effect) in combination with the weak lethal effect on emergence. The impact of fish on the feeding behaviour of the predatory larvae of R. fasciata and P. conspersa resulted in a switched prey composition, whereas a reduction in the daily feeding activity was not observed. That was supposed because of changes in the activity pattern by the predator R. fasciata or the changed prey availability for P. conspersa in the fish reach. A general reduction in feeding activity or animal food proportion of the omnivores was not assessed in the presence of fish. In contrast, the relations between the resources switched to a more variable utilisation in the fishless reach. The annual total consumption of invertebrate predators and omnivores was decreased by 20-50% in the fish reach, mainly caused by fish induced biomass reduction. The missing fish consumption could be at least balanced by higher invertebrate consumption in the fishless reach. Contrary, the prey specific consumption of invertebrate predators changed by behavioural-induced switch in the prey composition between the stream reaches. Therefore, a higher predation pressure on detritus feeding species (e.g Diptera) was found in the fishless reach, but not on the supposed key species of the potential biomanipulation (e.g. grazing mayflies). Due to the high importance of invertebrate predation in stream food webs, the aim of biomanipulation can only be reached by considering the populations of predatory invertebrates. Controlling the biomass of suitable benthivorous fish to an optimum (relatively high) level could sufficiently reduce the impact of invertebrate predators leading to an indirect enhancement of grazing species

Diving bradycardia, or a decrease in heart rate while diving, has been observed in a wide variety of species, from frogs to seals. The degree to which an animal lowers its heart rate during a submergence may vary depending on the behaviour of the animal. The leatherback sea turtle (Dermochelys coriaced) is an active diver, and has a metabolic rate that is higher than expected for a reptile of its size. The purpose of this research was to gain an understanding of the cardiovascular response to diving made by the leatherback turtle and to integrate this information with what is known of the turtle's diving behaviour and metabolism. Instruments capable of recording heart rate, dive duration and dive depth were deployed on leatherback females as they lay eggs on a nesting beach. Heart rate and diving variables were recorded during the internesting interval when turtles were freely diving at sea. Instruments were recovered when the turtles returned to the nesting beach to lay more eggs. Relationships between the turtle's diving behaviour and heart rate were examined, and comparisons were made between diving heart rates, surface heart rates, and long-term heart rates. Dive records show that leatherback turtles dive continually throughout the internesting interval. The brief amount of time spent at the surface between dives suggests that these turtles rely mainly on aerobic metabolism for routine dives, and all observed dives fell within the calculated aerobic dive limit. No significant diel differences existed for leatherback turtles from the Playa Grande nesting population, but dives became shorter and shallower as the internesting interval drew to a close. Neither dive duration nor dive depth was strongly related to heart rate. Diving heart rates were significantly lower than surface heart rates for leatherback turtles. The most likely cause of the observed diving bradycardia is increased pulmonary resistance accompanied by variable degrees of systemic perfusion. The fact that decreases in heart rate during diving were not extreme suggests that turtles do not drastically lower their metabolic rate while diving during the internesting interval. Long-term heart rates were more similar to diving heart rates than to surface heart rates.

While diving, harbour seals (Phoca vitulina) manage their oxygen stores through cardiovascular adjustments including bradycardia, a concurrent reduction in cardiac output, and peripheral vasoconstriction. At the surface, post-dive tachycardia facilitates rapid reloading of these oxygen stores. Although harbour seals can tolerate over 20 min of submergence, the majority of their natural dives are only 2 to 6 min and are usually followed by surface intervals that are less than 1 min, so they spend about 80 % of their time at sea submerged. Given that harbour seals meet their ecological needs through repetitive short aerobic dives, I was interested in the functional role, if any, of the cardiovascular dive response during these short dives. During voluntary diving in an 11 m deep tank, the cardiovascular responses to submergence of five captive harbour seals were manipulated using specific pharmacological antagonists, and the effects on diving behaviour were observed. Effects of pharmacological blockade on mean heart rate and on heart rate variability were also examined in order to assess the autonomic control of heart rate during voluntary diving. Heart rate was recorded using subcutaneous electrodes and a custom data logger while diving behaviour was monitored using a video camera. The muscarinic blocker methoctramine blocked diving bradycardia; the α-adrenergic blocker prazosin blocked diving vasoconstriction; and the β-adrenergic blocker metoprolol blocked post-dive tachycardia. Mean heart rate analysis revealed that diving bradycardia is primarily modulated by the vagus, and post-dive tachycardia is due to increased sympathetic stimulation of the heart as well as parasympathetic withdrawal. Results of power spectral analysis of heart rate variability supported the conclusion that the parasympathetic nervous system predominates during diving but not during surface intervals. None of the pharmacological blockers had any effect on average dive or surface interval duration. Mean dive duration ranged from 2.3±0.47 to 2.9±0.10 min (mean±S.E.M.) for all treatments including controls, and mean surface interval duration ranged from 23 to 29 sec. Seals maintained a high percent dive time (83 to 87 %) in all treatments including controls. Thus, harbour seals do not need the dive response during short dives in order to maintain an efficient dive strategy.

Effective conservation strategies for sea turtles require knowledge of animal movements and protection of biologically important habitats and life history stages. For breeding adult sea turtles, understanding both their inshore and pelagic spatial patterns is imperative to the successful protection of the species and the accurate identification of their vulnerabilities. This study provides insight into the inter-nesting, post-nesting, and foraging movements of green sea turtles (Chelonia mydas) that nest on Bioko Island, Equatorial Guinea, by using satellite telemetry to track green turtles (n=12) during two nesting seasons (2017-18, 2018-19), and as they migrated to foraging grounds after the nesting season. These tracks were fit with a switching state space model to characterize movements, and then analyzed in relation to environmental and anthropogenic factors. Dive depth data was also used to determine utilization patterns within the water column. The 12 tagged turtles migrated for an average of 1064 km to two distinct foraging grounds, with 10 migrating west for an average of 1115 km to the coastal waters of Ghana, and 2 migrating south for an average of 1563 km to the coastal waters of Angola. Migrating turtles used both direct, pelagic migration strategies, and biphasal, coastal strategies, which included intermittent foraging throughout migrations. Dive depths varied depending on behavior, with an average of 19.3 m during inter-nesting, 12.6 m during migration and 8.5 m during foraging. Knowledge of inter-nesting habitat use, migration patterns, and foraging ground locations will be critical for the development of marine conservation management plans in the Gulf of Guinea and aide in sea turtle conservation efforts throughout the area. Additionally, spatial and dive depth data can inform zonal fishing regulators and provide information needed for modifications to fishing practices and gear that is most likely to reduce sea turtle bycatch. These data will provide a more complete understanding of marine areas critical to sea turtle conservation and aide in sustainable economic development in the Gulf of Guinea.

The critically endangered grey nurse shark (Carcharias taurus) off eastern Australia is the focus of a non-consumptive, economically important marine wildlife tourism (MWT) industry centred on scuba diving with the sharks. This industry has been identified as a potential threat to the continued survival and recovery of the species. Legislative guidelines and a national code of conduct for scuba diver behaviour were developed to mitigate adverse impacts of MWT on the sharks. This research assessed the putative impacts of scuba diving MWT on grey nurse shark behaviour and the efficacy of management strategies across differing life-history stages and aggregation sites. Underwater stereo-video photogrammetry was used to develop a partial ethogram of the swimming and non-swimming behaviours of grey nurse sharks at locations within aggregation sites during daylight hours without MWT. Predominantly low-energy behaviours were exhibited and no threatening agonistic behaviours were observed. Underwater visual census also documented primarily low-activity swimming behaviours in sharks during interactions with MWT scuba divers of varying demographics and revealed absolute diver compliance with management guidelines. Passive acoustic telemetry showed sharks may have exhibited more active swimming when patrolling between two locations within a site but adopted low-energy swimming behaviours for the majority of the time during daylight hours regardless of scuba diving MWT. Sharks at differing life-history stages probably conserved energy at aggregation sites in association with their migratory movements and reproductive cycles. Differences in the swimming and patrolling behaviours of sharks were attributed to natural variation in environmental conditions (i.e. topography and currents) at the sites as they were not consistent with scuba diving MWT activity. This research strongly suggested that management strategies are effective at protecting the east Australian population of grey nurse sharks from MWT disturbance. Consequently, the grey nurse shark scuba diving MWT industry in its current form is ecologically and economically sustainable.

Chapter 1 Introduction. Chapter 2 Gross and microscopic visceral anatomy of the male Cape fur seal with reference to organ size and growth. Chapter 3 Age determination and growth in the male Cape fur seal: part one, external body. Chapter 4 Age determination and growth in the male Cape fur seal: part two, skull. Chapter 5 Age determination and growth in the male Cape fur seal: part three, baculum. Chapter 6 Suture age as an indicator of physiological age in the male Cape fur seal. Chapter 7 Sexual dimorphism in the adult Cape fur seal: standard body length and skull morphology. Chapter 8 Reproduction in the male Cape fur seal: age at puberty and annual cycle of the testis. Chapter 9 Diet and foraging behaviour of the Cape fur seal. Chapter 10(a) The Impact of the fur seal industry on the distribution and abundance of Cape fur seals. Chapter 10(b) South African Airforce wildlife rescue: Cape fur seal pups washed from Black Rocks, Algoa Bay, during heavy seas, December 1976. Chapter 11(a) Operational interactions between Cape fur seals and fisheries: part one, trawl fishing. Chapter 11(b) Operational interactions between Cape fur seals and fisheries: part two, squid jigging and line fishing. Chapter 11(c) Operational interactions between Cape fur seals and fisheries: part three, entanglement in man-made debris. Chapter 12 Concentrations of heavy metals (Cd, Cu, Pb, Ni & Zn) and organochlorine contaminants (PCBs, DDT, DDE & DDD) in the blubber of Cape fur seals. Chapter 13 Endoparasites of the Cape fur seal. Chapter 14(a) Preliminary investigations of shark predation on Cape fur seals. Chapter 14(b) Aggressive behaviour of an adult male Cape fur seal towards a great white shark Carcharodon carcharias. Chapter 15 Conclusions and future directions.

The western North Atlantic population of the northern right whale (Eubalaena glacialis) was severely depleted by whaling over the last century. Despite over fifty years of protection, fewer than four hundred individuals are believed to exist in the North Atlantic. Relatively little is known about the diving behavior, respiratory physiology, or diel activity of these whales, although such information could be useful in predicting population abundance and distribution in relation to food or environmental variables. Dive behavior data can be collected visually, but collection is limited to daylight hours, calm weather, and fortuitous encounters with study animals. Satellite-monitored radio tags offer the opportunity to collect data on individual whales' diving behavior continuously, over long distances and periods of time, and at relatively low cost. Thirteen North Atlantic right whales were tagged and monitored in the Gulf of Maine between 1989 and 1991. One male was tagged in 1989; two adult males, six adult females (two with calves) and one juvenile were tagged in 1990; one adult female (with a calf) and two juveniles were tagged in 1991. The duration of monitoring for the whales varied from <1 day to 43 days. Characteristics of the radio tags were different over each year in order to evaluate different attachment mechanisms and methods of collecting and summarizing data for dive duration, dive frequency, and time submerged. These data were then used to describe the dive behavior and to predict aspects of the respiratory physiology for these whales. The number of dives, their duration, and the time submerged varied considerably among individual whales and between years. Over all, the whales spent 79% of their time underwater. However, most dives were short (i.e., 95% were <14 min; the mean dive duration was 92.3 sec), although dives of 30-40 min duration were observed for several individuals. In general, the number of dives a right whale made was inversely related to the average duration of its dives within a time interval. Furthermore, over a given time interval, the number of times a whale dove was a better predictor of the percent time it was submerged than was the average duration of its dives. There was no evidence of diel variation in dive behavior (i.e., number of dives, average dive duration, or percent time submerged) among these whales. Age, sex, and reproductive status may have affected dive behavior, although these trends were not statistically significant due to the small number of study animals and individual behavioral variability. Males tended to dive more often and averaged shorter dives than females. Females with calves dove more often and averaged shorter dives than females without calves. Juvenile females dove less often but averaged longer dives than adult males or females with calves. It was predicted that the aerobic dive limit of an "average" right whale was approximately 14 min. Ninety-five percent of the dives recorded for the 11 monitored right whales were < 14 min. Furthermore, there was no evidence of recuperative periods (i.e., prolonged periods at the surface) after long dives. These observations were consistent with the idea that the North Atlantic right whales dove within their aerobic scope. They further suggest that physiological parameters alone probably have little influence on dive characteristics, except to set an upper limit on the duration of a dive. Satellite telemetry provides an opportunity to monitor the movements and behavior of free-ranging animals, and overcome many of the short-comings associated with traditional, human-based visual techniques for tracking and studying such animals. Although the tags used in this study were prototypes and varied in their design from year to year, several right whales were monitored simultaneously and were tracked over thousands of kilometers. Advances in tag miniaturization, attachment, and software will likely extend the time tags stay attached and the detail of the behavioral and environmental variables that can be monitored. As testimony to the power of this technology, this application of satellite telemetry to monitor great whales yielded one of the most extensive, long-term, continuously-monitored data sets yet recorded on the diving behavior of a baleen whale.
Graduation date: 1993

M.A. (Social Work)
The function of social work is to enhance the social functioning of individuals, smaller groups (including families) and the community. This implies need meeting and growth-promoting activities for the purposes of reinforcing, enhancing or discouraging inappropriate behavior. In order to achieve success , social workers need to explore every avenue of helping, so that the client with his unique needs are always held in respect and helped the most successfully. Behavior modification, although still underdeveloped in social work, is one of the numerous approaches that can be utilised to meet the needs of the social work clientele ...