A great deal of work has been done on the ecology of the intertidal some of South African by the Zoology Department of the University of Cape Town under the direction of Professor T.A. Stephenon. As a result of this a number of valuable papers have been published dealing with the plants and animals of the zone, their ecology, lateral and vertical distribution and so on. Stephenon has, in three papers (1939, 1944,1947), dealt with general results and conclusions drawn from this survey. This work dealt entirely with the biotic between tidelevels, i.e., from the sublittoral fringe upward. it did not take into account the sublittoral, that part of the shallow coast which is perpetually submerged at all tides.

Wide bandgap devices are the future of this dynamically changing technological world. Considering Gallium Nitride (GaN) and Silicon Carbide (SiC), GaN has exceptional characteristics that will likely allow it to proliferate greatly in the area of low-and-mid-power power electronic converters. One of the current challenges in this context to completely utilize GaN are the reliability issues, especially false turn-on events, which is a main focus of this thesis. False turn-on due to its momentary short circuit capability deteriorates the converter performance. Furthermore, simple and accurate modeling of GaN device losses is critical to help electronic designers optimize converter designs. This thesis focuses on three contributions to help reduce false turn-on events and improve GaN modeling efforts. First, this work uniquely investigates the optimal pulse-width-modulation (PWM) scheme to balance efficiency and false turn-on. The experimental results lead to a recommendation to use a larger negative bias than is currently recommended by device manufacturers. Secondly, the work proposes a new simplified switching loss model with high accuracy that can be used with different gate drive circuits (including negative gate bias voltages) to make it more useful for power electronics design engineers as a tool. And thirdly, since the main contributor to false turn-on events are the parasitic inductances in the switch and on the PCB, this work proposes a new parasitic inductance measurement methodology which can be implemented using only simple laboratory instruments. / Thesis / Doctor of Engineering (DEng) / Wide bandgap devices are the future of this dynamically changing technological world. Considering Gallium Nitride (GaN) and Silicon Carbide (SiC), GaN has exceptional characteristics that will likely allow it to proliferate greatly in the area of low-and-mid-power power electronic converters. One of the current challenges in this context to completely utilize GaN are the reliability issues, especially false turn-on events, which is a main focus of this thesis. False turn-on due to its momentary short circuit capability deteriorates the converter performance. Furthermore, simple and accurate modeling of GaN device losses is critical to help electronic designers optimize converter designs. This thesis focuses on three contributions to help reduce false turn-on events and improve GaN modeling efforts. First, this work uniquely investigates the optimal pulse-width-modulation (PWM) scheme to balance efficiency and false turn-on. The experimental results lead to a recommendation to use a larger negative bias than is currently recommended by device manufacturers. Secondly, the work proposes a new simplified switching loss model with high accuracy that can be used with different gate drive circuits (including negative gate bias voltages) to make it more useful for power electronics design engineers as a tool. And thirdly, since the main contributor to false turn-on events are the parasitic inductances in the switch and on the PCB, this work proposes a new parasitic inductance measurement methodology which can be implemented using only simple laboratory instruments.

In this thesis we develop a model which allows us to evaluate Modified Dorfman's and Modified Sterrett's group testing procedures in the presence of false positive classification error that can be used for screening blood for HIV. Performance measures derived are the expected number of tests per sample and the corresponding coefficient of variation. The procedures differ from the original ones by the fact that groups and samples are retested certain number of times before they are classified as positive. Modified Individual testing procedure and the procedure currently used by Canadian Red Cross are also evaluated and all four testing strategies are compared. Numerical analysis illustrates that group testing is more efficient than alternatives. / Thesis / Master of Science (MSc)

This study examined whether schemas formed during training (graduate coursework, clinical supervision, etc.) are responsible for the tendency of clinicians to experience higher rates of false recall for clinical case details when compared to novices. Participants in this study were recruited from a general psychology class to limit preexisting knowledge of psychological disorders. Half of the participants were trained to recognize features of Generalized Anxiety Disorder with the purpose of forming a schema for that disorder, whereas the other half were not. Participants’ memory for the diagnostic and non-diagnostic details within a hypothetical case vignette was tested using a free recall prompt followed by a yes/no recognition test. Trained participants falsely recognized the diagnostic detail ‘restlessness’ and falsely recalled the diagnostic detail ‘uncontrollable worry’ at a significantly higher rate than controls, suggesting that the training successfully formed a schema for GAD symptoms.

The Federal Aviation Administration (FAA) wishes to minimize the overall operational costs of their aviation security detection systems. These systems consist of a collection of security devices. The objective of this research is to develop an algorithm to design the optimal system of devices. The Secure Air Flight Effectiveness (SAFE) Model accomplishes this objective by using the probability of detection and the probability of giving a false alarm for each individual device. A Generalized Hill Climbing (GHC) algorithm was implemented to identify the system with the minimum operational cost. Suggestions for future research directions are also included. / Master of Science

No description available.

published_or_final_version / Clinical Psychology / Master / Master of Social Sciences

The primary objective of the present thesis was to investigate factors that influence the creation of false memories using the Deese-Roediger-McDermott (DRM) paradigm. The experimental research addressed the effect of age, list length, and list content on the magnitude of the DRM illusion with a view to testing assumptions derived from activation-monitoring theory and Fuzzy Trace Theory. In the first experiment, I wanted to determine whether the DRM paradigm is appropriate for use with New Zealand English-speaking adults. In addition, Experiment 1 was designed to assess the effect of prior recall on recognition performance. To answer these questions, I assigned half of the participants to a recall-plus-recognition condition and the remaining participants to a recognition-only condition. Rates of false recall and recognition were comparable to those reported in the literature, which suggested that the task is suitable for use with New Zealand adults. Furthermore, prior recall enhanced correct recognition but it did not affect false recognition. In Experiment 2, I examined how manipulations of list-length affected children and adults' susceptibility to the DRM illusion. Ten-year-olds and adults studied eight lists of either 7 or 14 words. In the 14-word condition, adults falsely recalled more critical targets than children; however, in the 7-word condition, there was no age difference in false recall. In addition, adults falsely recognised a greater proportion of critical targets than children, however, this effect was not dependent on the length of the study list. In Experiments 3A and 3B, I examined whether presenting highly familiar study materials would enhance children's susceptibility to false memories. Ten-year-old children and adults studied four standard DRM lists, four new lists that centred on 'child-friendly' concepts, such as birthday and school (CF lists), and four lists derived from child word-association norms. In both experiments, there was no age difference in rates of false recall. In addition, presenting material that was deemed more developmentally appropriate did not enhance children's susceptibility to false memories relative to adults. In Experiment 4, I introduced a post-recall phase to examine why the DRM illusion is less likely to occur when short lists are presented and when the materials are child-friendly. During the post-recall phase, participants were asked to report any other words that they had thought of during the presentation or recall of the study lists. Thinking about the target word, but remembering that it had not been presented, could not account for decreased levels of false recall in the short-list condition. Similarly, with the CF lists, it appeared that the list items were less likely to activate the critical target for both children and adults. In the final three experiments, I explored the assumptions outlined in activation-monitoring theory and fuzzy-trace theory to determine which model provided the best account of the findings obtained to date. To explore the activation-monitoring account, children and adults completed word association tasks. To explore fuzzy-trace theory, children and adults were given a gist extraction task where they had to identify the critical targets associated with each list. Collectively, the results of the present thesis fit more comfortably within an activation-monitoring framework than they do within the fuzzy-trace framework. Although the precise mechanisms underlying the DRM illusion have yet to be elucidated, the present findings suggest that gist extraction, activation processes, and source monitoring each play a substantial role in mediating false memory levels.

AMANDA-II est un télescope à neutrinos composé d'un réseau tri-dimensionnel de senseurs optiques déployé dans la glace du Pôle Sud. Son principe de détection repose sur la mise en évidence de particules secondaires chargées émises lors de l'interaction d'un neutrino de haute énergie (> 100 GeV) avec la matière environnant le détecteur, sur base de la détection de rayonnement Cerenkov. Ce travail est basé sur les données enregistrées par AMANDA-II entre 2000 et 2006, afin de rechercher des sources cosmiques de neutrinos. Le signal recherché est affecté d'un bruit de fond important de muons et de neutrinos issus de l'interaction du rayonnement cosmique primaire dans l'atmosphère. En se limitant à l'observation de l'hémisphère nord, le bruit de fond des muons atmosphériques, absorbés par la Terre, est éliminé. Par contre, les neutrinos atmosphériques forment un bruit de fond irréductible constituant la majorité des 6100 événements sélectionnés pour cette analyse. Il est cependant possible d'identifier une source ponctuelle de neutrinos cosmiques en recherchant un excès local se détachant du bruit de fond isotrope de neutrinos atmosphériques, couplé à une sélection basée sur l'énergie, dont le spectre est différent pour les deux catégories de neutrinos. Une approche statistique originale est développée dans le but d'optimiser le pouvoir de détection de sources ponctuelles, tout en contrôlant le taux de fausses découvertes, donc le niveau de confiance d'une observation. Cette méthode repose uniquement sur la connaissance de l'hypothèse de bruit de fond, sans aucune hypothèse sur le modèle de production de neutrinos par les sources recherchées. De plus, elle intègre naturellement la notion de facteur d'essai rencontrée dans le cadre de test d'hypothèses multiples.La procédure a été appliquée sur l'échantillon final d'évènements récoltés par AMANDA-II. --------- MANDA-II is a neutrino telescope which comprises a three dimensional array of optical sensors deployed in the South Pole glacier. Its principle rests on the detection of the Cherenkov radiation emitted by charged secondary particles produced by the interaction of a high energy neutrino (> 100 GeV) with the matter surrounding the detector. This work is based on data recorded by the AMANDA-II detector between 2000 and 2006 in order to search for cosmic sources of neutrinos. A potential signal must be extracted from the overwhelming background of muons and neutrinos originating from the interaction of primary cosmic rays within the atmosphere. The observation is limited to the northern hemisphere in order to be free of the atmospheric muon background, which is stopped by the Earth. However, atmospheric neutrinos constitute an irreducible background composing the main part of the 6100 events selected for this analysis. It is nevertheless possible to identify a point source of cosmic neutrinos by looking for a local excess breaking away from the isotropic background of atmospheric neutrinos; This search is coupled with a selection based on the energy, whose spectrum is different from that of the atmospheric neutrino background. An original statistical approach has been developed in order to optimize the detection of point sources, whilst controlling the false discovery rate -- hence the confidence level -- of an observation. This method is based solely on the knowledge of the background hypothesis, without any assumption on the production model of neutrinos in sought sources. Moreover, the method naturally accounts for the trial factor inherent in multiple testing.The procedure was applied on the final sample of events collected by AMANDA-II.

Thesis (M.A.)--University of North Carolina at Wilmington, 2004. / Includes bibliographical references (leaves : 86-92).