Thesis (M. Communication Pathology)--University of Pretoria, 2006. / Summary in English and Afrikaans. Includes bibliographical references.

This thesis presents new 450$\mu$m and 850$\mu$m observations of NGC3627 taken with the new SCUBA-2 with the main goal of trying to better understand the properties of gas and dust in the interstellar medium of NGC3627. We determined properties of the cold component of NGC3627's spectral energy distribution (SED) using dust models given by the Planck Collaboration, by Li and Draine, and allowing the emissivity index to be treated as a free parameter. Fitting the SED required the use of 100$\mu$m, 160$\mu$m, 250$\mu$m, 350$\mu$m, and 500$\mu$m data from the KINGFISH survey. Each of the KINGFISH observations have been passed through an extended emission filter in order to match the SCUBA-2 observations. The best fit temperatures and emissivity indices agreed with the results found in other recent studies, but our fitted masses were smaller than those of other studies due to differences in the fitted temperature and observed fluxes. After the properties of the dust emission were calculated, we implemented a method to determine the amount of molecular hydrogen present in NGC3627. The method we used involves finding a CO-to-H$_2$ conversion factor that minimizes the scatter present in dust-to-gas mass ratio. We used CO J=2-1 from the HERACLES survey and CO J=1-0 from the Nobeyama 45-m telescope to act as our molecular tracer, and HI observations of NGC3627 from the THINGS survey. The results from minimizing the dust-to-gas ratio scatter give low $\alpha_{CO}$ values, that are normally associated with U/LIRGs. The low $\alpha_{CO}$ values can be attributed to the treatment of the error associated with reported $\alpha_{CO}$. The uncertainties for $\alpha_{CO}$ reported in this thesis are a minimum estimate, and if the error associated with $\alpha_{CO}$ is large enough, then the best fit $\alpha_{CO}$ values can be considered as a lower threshold for the system. / Thesis / Master of Science (MSc)

[Truncated abstract] Introduction, Little is known about the prevalence of post-course diving injuries amongst Western Australian recreational divers, nor is it known which risk factors affect the Western Australian diver’s likelihood of sustaining a diving injury. Objective, The aim of this study was to measure the prevalence of diving-related injuries amongst Western Australians with varying experience since certification as entry-level divers within Western Australia (WA). Specifically, the study compared divers’ experience, behaviour and equipment with their diving injury history. It was hypothesised that diving experience has an effect upon the likelihood of a certified diver suffering any of the diving injuries most commonly reported amongst international diving populations. In addition, the strength of association between diving injuries and other potential risk factors was measured amongst certified Western Australian divers. Methods, A cross sectional survey of Western Australians, whom had completed a recognized entry-level recreational scuba diving course within WA, formed the basis of the study. Diver training facilities within WA posted a four-page questionnaire to divers they had trained to entry-level within the previous six years. The self-administered questionnaire collected data describing the divers’ post-course participation in scuba diving, injury prevalence during the last year, demographic characteristics and prevalence of known or hypothesized diving injury risk factors ... Conclusion, In this study diving experience, measured by the number of dives made during the previous year and the total number of dives made since certification, has not been found associated with the likelihood of reporting having suffered at least one diving injury of any type whilst diving during the previous year. Whilst the limited response rate and self-reporting methodology threaten the validity of the findings of this study, the findings improve our understanding of the type of diving injuries commonly suffered by divers, and of which risk factors are associated with a diver’s likelihood of suffering a diving related injury within WA. These findings may assist the design of further diving injury research, ultimately leading to the design of diving safety interventions aimed at reducing the prevalence of diving injuries amongst Western Australian recreational divers.

Over the last 50 years there has been a rapid increase in global landings of cephalopods (octopus, squid and cuttlefish). In European waters, cuttlefish are among the most important commercial cephalopod resources and within the North-East Atlantic, the English Channel supports the largest cuttlefish fishery, with the common cuttlefish, Sepia o cinalis (Linnaeus, 1758), dominating landings. S. o cinalis has a short (2 year) life cycle in the English Channel that is punctuated by seasonal migrations inshore and o shore. Using a combination of di erent métiers including beam trawling, otter trawling and coastal trapping, this shared fisheries resource is targeted at nearly every phase of the life cycle. Despite this continuing increase there remain only minimal management measures in place, with no quotas, no total allowable catches, no closed areas, no minimal landing size and no routine assessment of stocks. In order to provide sustainable fisheries management advice for S. o cinalis populations it is essential that a thorough understanding of the ecology and life history of this species, in particular the factors a ecting spawning and recruitment variability, is attained.In this thesis, I examine critical gaps in our understanding of the distribution, movements, habitat use and behaviours of spawning and sub-adult S. o cinalis. This research provides baseline data for this species within the inshore waters of the English Channel and uses a combination of novel field-based electronic tracking techniques, in situ subtidal observations of spawning patterns within natural environments and presence-only species distribution modelling. A maximum entropy (MaxEnt) modelling approach was used to predict the distribution of benthic egg clusters using presence-only data. The model showed very good performance in terms of predictive power and accuracy (test area under the receiver operating characteristics curve [AUC] = 0.909) and among the explanatory variables used to build the model, depth (gain = 1.17), chlorophyll-a concentration (used here as a proxy for turbidity; gain = 1.06) and distance from coastline (gain = 1.02) were shown to be the greatest determining factors for the distribution of S. o cinalis spawning. As part of the model output, maps (logistic and binary) of the predicted spawning distribution of S. o cinalis within the English Channel were produced.Subtidal observation were undertaken at spawning grounds on both the North and South coast of the English Channel to investigate spawning habitat and structure use. A total of 15 types of natural spawning structures were identified. The range of spawning structures used varied among sites with Zostera marina identified as the dominant spawning structure at two of the UK sites (Torbay and Poole Bay), potentially indicating a ‘preference’ for this structure within localities. Fractal dimension analysis of the seagrass beds at Torbay revealed that the spatial dynamics of seagrass beds within this site varied significantly between 2011 and 2012 (Mann- Whitney U: Z = 4.92, P < 0.0001) as a result of both anthropogenic and natural disturbance. Interannual changes in the spatial dynamics of these beds could a ect the annual pattern and intensity of spawning at a site. The use of structures with small diameters was found to occur, with cuttlefish adapting the device to their requirements by utilising multiple leaves or thalli in order to achieve a suitable diameter for egg attachment, this was evident in their use of both Chorda filum and Z. marina.This research also provided the first data on the fine-scale movements and behaviours of adult and sub-adult individuals, tracked within their natural environments, using electronic tagging methodologies. That expected patterns of short-term spawning site fidelity at a local level were observed in only two individuals, whilst larger scale movements (up to 35 km) along the coastline were observed in three individuals, indicated that a range of behaviours and movement patterns could occur among spawning adults. Similarly varied patterns of site fidelity were also observed in tagged sub-adults, tracked over an extended period (up to 73 days), using a static acoustic array. These results highlight the complex range of patterns and plasticity in behaviour that exist within natural populations.In summary, a series of di erent approaches was used within this thesis in an e ort to improve our understanding of the fine-scale movement, behaviours and habitat use of S. o cinalis (in both spawning adults and non spawning sub-adults), as well as their potential spawning distribution within the inshore waters of the English Channel. Observing the movements and behaviours of small marine animals like S. o cinalis in their natural environments has traditionally been di cult. Recent developments in technologies and techniques however, including those used within this thesis (e.g. electronic tagging), have highlighted the potential capacity of novel tools to monitor the in situ movements and behaviour of cuttlefish. By providing important insights into the ecology of this species these new tools can aid conservation and management advice for this important commercial fishery species, both within the English Channel and further afield.

Digitized by Kansas Correctional Industries

In SCUBA diving, the propulsive efficiency of a diver regulates, in part, his autonomy. An inefficient method of propulsion will increase the power output required and, therefore, the intake of oxygen and increase fatigue. Since the development of the SCUBA apparatus, fins have evolved based on the designer's intuition and knowledge of hydrodynamics. Some experimental work has been performed, but it is usually limited to studying the diver as whole and does not focus on the fin design. In this dissertation, a state-of-the-art fluid-structure interaction framework is developed and then used to study fin propulsion. This framework couples the structural dynamics of the fin with the fluid dynamics surrounding it using a modular framework. This way, mature state-of-the-art solvers can be used in each domain (structural and fluid). The flow field is solved using a computational fluid dynamics solver which resolves the Navier-Stokes equations. Coupled with these equations are a variety of turbulence models which can be used to resolve the turbulence in the flow. The CFD method is validated using a two-dimensional circular cylinder and a pitching and heaving airfoil, both immersed in a turbulent flow field. A commercial structural dynamics solver, is used to resolve the structural dynamics. The coupling of the two solvers is also described in detail. The basic design of a fin (a simple flat plate) is studied and modified in order to test the effect that altering key structural parameters has on the thrust, power and efficiency of the fin. The end result is a set of design recommendations which can be used to enhance the performance of a SCUBA fin. These recommendations are based on both quantitative and qualitative analysis of the performance characteristics of the fin.

Thesis (M.F.A.)--Rochester Institute of Technology, 1992. / Typescript. Includes bibliographical references (leaf 44).

O hidrÃide calcÃrio do gÃnero Mil/epora ocorre em regiÃes tropicais de todo o planeta como um componente regular dos recifes de coral. MilÃporas sÃo encontradas em profundidades menores que 1 atà 40 m. Os corais vivos criam uma sÃrie rica de habitats para um grande nÃmero de espÃcies fornecendo substrato para os organismos sedentÃrios e alimento ou abrigo para os organismos mÃveis. O objetivo deste estudo foi identificar e quantificar toda a macrofauna encontrada em colÃnias de Mil/epora a/cicornis na Ãrea de ProteÃÃo Estadual dos Recifes de Coral (RN). As 26 amostras foram coletadas manualmente atravÃs de mergulho autÃnomo, em profundidades de 1 a 3 m. No perÃodo de julho e novembro de 2004 e fevereiro de 2005, as colÃnias foram envolvidas por sacos plÃsticos e, em seguida, extraÃdas do substrato com o auxÃlio de martelo e talhadeira. Posteriormente, as amostras foram fixadas com formalina 4%. No laboratÃrio, as colÃnias foram analisadas para a retirada dos epibiontes e, em seguida, cuidadosamente fragmentadas para a remoÃÃo da fauna perfurante. Foram registrados 1.234 indivÃduos e 95 espÃcies de organismos nÃo coloniais dos grupos Crustacea, Echinodermata, Mollusca, Nemertea, Polychaeta e Sipuncula, e 86 colÃnias e 26 espÃcies de organismos coloniais dos tÃxons Cnidaria, Porifera e Tunicata. Os crustÃceos apresentaram o maior nÃmero de indivÃduos e espÃcies, seguidos por poliquetas e moluscos. Segundo coeficiente de correlaÃÃo de Spearman, o nÃmero de indivÃduos e espÃcies dos organismos nÃo coloniais associados aumenta com o crescimento da colÃnia. Em relaÃÃo à fauna colonial, os tunicados possuÃram maior nÃmero de colÃnias e os porÃferas, maior nÃmero de espÃcies. A epifauna dos grupos coloniais e nÃo coloniais foi mais numerosa que a endofauna. ComparaÃÃes entre milÃporas e corais escleractÃnios podem ser traÃadas devido a uma possÃvel convergÃncia funcional desses tÃxons. à possÃvel supor que as associaÃÃes com corais nÃo dependem exclusivamente da espÃcie hospedeira, pois espÃcies distintas habitam a mesma espÃcie de coral em regiÃes diferentes. Provavelmente o substrato exerÃe papel mais importante, cujas formas promovem a formaÃÃo de habitats distintos. / The limestone of the genus hidrÃide Mil / epora occurs in tropical regions around the planet as a regular component of coral reefs. MilÃporas are found at depths less than 1 to 40 m. The live coral create a rich variety of habitats for many species by providing substrate for sedentary organisms and food or shelter for the bodies moving. The aim of this study was to identify and quantify all the macrofauna found in colonies of Mil / epora a / cicornis Area of Protection of Coral Reefs of the State (RN). The 26 samples were collected manually through autonomous diving in depths from 1 to 3 m. In the period from July to November 2004 and February 2005, the colonies were surrounded by plastic bags and then extracted from the substrate with the aid of hammer and chisel. Subsequently, the samples were fixed with formalin 4%. In the laboratory, the colonies were tested for the withdrawal of epibiontes and then carefully to remove fragmented fauna Perforating. 1234 individuals were recorded and 95 species of non-colonial groups of Crustacea, Echinodermata, Mollusca, Nemertea, and Sipuncula Polychaeta, and 86 colonies and 26 species of organisms colonial taxa of Cnidaria, Porifera and Tunicata. The crustaceans had the highest number of individuals and species, followed by polychaetes and molluscs. According to Spearman correlation coefficient, the number of individuals and species of non-colonial increases associated with the growth of the colony. Regarding colonial fauna, tunicates owned the largest number of colonies and Porifera, greater number of species. The epifauna of non-colonial and colonial groups was larger that endofauna. Comparisons between milÃporas and coral escleractÃnios can be drawn due to a possible functional convergence of these taxa. You can assume that the associations with corals do not depend exclusively on the host species, as different species inhabit the same species of coral in different regions. Probably the most important role exercise substrate, which forms promote the formation of distinct habitats.

A study was conducted to investigate the effects of a hypertext - based computer simulation on the knowledge, skills and attitudes of students participating in a high school scuba program in Edmonton, Alberta. The study compared two groups of students: one which used the simulation as a supplementary (laboratory-type) activity, and another which was taught using traditional methods. The two groups received an equal amount of instrutional time. The simulation and non-simulation groups were found to be equilvalent at the beginning of the study with respect to age, gender, previous diving experience, previous computer experience, attitude toward computers and attitude toward diving. After instruction, the simulation and non-simulation groups were examined for differences with respect to knowledge, attitudes and behaviour, using the following measurement instruments: Knowledge: Marks from students' certification examinations were used as a measure of general diving knowledge. Attitudes: Students were post-surveyed for attitudes toward diving using a locally developed attitude scale. Behavior: Students were evaluated using a locally developed skills assessment to determine their degree of proficiency at out-of-air emergency skills. Reliability estimates for the locally developed instruments were .86, .88 and .93 for the diving attitude, computer attitude and out-of-air skills instruments, respectively. A series of t-test comparisons revealed no significant differences (p<.05) between simulation and non-simulation groups with respect to knowledge, skills and attitudes. The relationships between knowledge, skills and attitudes were examined using Pearson's correlation coefficient, and a significant (p<.01) positive correlation was found between the knowledge and skill measures, with r=0.69. A "diversion index" (DI=# of non-ideal cards in attempt/total # of cards in attempt) was calculated for each attempt made by each student on each of the scenarios. A pattern in diversion indices was revealed, and generalized into a model consisting of four stages: discovery, refinement, solution and exploration. This model is suggested as one way students may approach simulation learning. Six volunteers were interviewed to determine students' opinions regarding the effects of the simulation. Students stated that the simulation helped with the development of in-depth knowledge about out-of-air emergencies, but not with the development of out-of-air emergency skills. Students said that they liked the simulation and enjoyed using it. Implications of the study are discussed with emphasis on research methodology, diver education, and environmental education, and a number of suggestions for future research are offered. / xi, 142 leaves : ill. ; 29 cm.

When scuba diving under a physical overhead such as a cave, a mine, a shipwreck, or under a virtual overhead due to decompression requirements, it makes it impossible to safely access the surface in the event of an emergency. Therefore, diving with overhead is often described as technical diving. In this research, I address how technical divers in Outaouais, Quebec, practice this risky sport with unforgiving consequences. Based on fieldwork in Outaouais, I focus on divers, including myself, who perform trimix dives deeper than 200 feet. I argue that the process of becoming a deep diver is a lifelong journey where a diver learns to adapt to a milieu hostile to human life. The basic skills are acquired during classes to ensure that a novice diver will survive in this limit-environment. As divers bend the rules and take more risks to go deeper for longer lengths of time, they will go through a series of limit-experiences and near misses that are essential to their development and found to be regenerative. In turn, those limit-experiences and near-miss events shared with teammates create mutual trust. It is this trust that becomes the foundation of the team and allows the team to improve upon existing techniques and increase the depth and difficulty of their dives.