Sensorless speed estimation in induction machines (IMs) presents an attractive proposition for eliminating the need for physical speed measurement sensors and thus avoiding the associated reliability and cost issues, such as the requirement of extra wiring, careful mounting, maintenance and adjustment. In this thesis, the feasibility of utilising the stator current and power signals to establish spectral search based (SSB) sensorless speed estimation schemes in wound rotor induction machines (WRIMs) operating in extended slip and open-loop controlled conditions is investigated. The research is performed on three different industrial WRIM designs. The thesis first investigates the spectral content of WRIM electrical and mechanical signals with the principal aim of identifying spectral patterns that can facilitate the development of real-time sensorless speed estimation. The examination is based on detailed harmonic models of the considered machine designs as well as experimental results obtained from tests performed on laboratory test rigs. A generalised theoretical analysis of the possible spectral content of machine signals that enables the derivation of closed form analytical expressions linking individual spectral frequencies to rotor speed is also undertaken. The results demonstrate that it is possible to clearly identify speed dependent components in the stator current and power signals and map the boundaries of the narrowbands maximised by these for extended slip and open-loop operating conditions. To enable improvement in attainable real time SSB estimation rates a dichotomous search algorithm real-time spectral processing method was employed for frequency tracking in this research. The algorithm performance is evaluated in real-time tests performed on a measured steady-state laboratory machine stator current and power signals. The results demonstrate that the dichotomous routine provides an inherent advantage in the frequency estimation rate without compromising the estimation accuracy and can therefore enable significant estimation rate improvement in SSB speed estimation algorithms. Novel sensorless speed SSB estimation techniques are then proposed for WRIM operation in extended slip and voltage/frequency controlled conditions. The algorithms utilise the reported analysis of electrical signals and are separately defined for each assessed operation mode and the stator current, phase power and three-phase power signals. It is shown that, in principle, power signal based estimation algorithms can offer an inherent capability of estimation rate reduction. A novel adaptive sliding window algorithm is defined for open-loop operating conditions that enable estimation in a wide operating speed range while minimising the potential for undesirable overlap with PWM harmonics. The proposed algorithms have been verified and their performance limitations assessed in real-time experiments on three different industrial WRIM designs. It is shown that reliable real-time speed estimation in steady-state and transient operating conditions is possible at an improved estimation rate while maintaining a low estimation error.

It is the purpose of this thesis to examine systematically the theories of selected sociologists and anthropologists with the end in view of determining whether or not or to what degree the various dichotomies are valid and useful. In addition to specific criticisms of doctrines peculiar to individual theorists, an attempt will be made to answer the following questions: What are the theoretical sources from which the dichotomies of types of social life in modern sociological and anthropological theory are derived? Are the dichotomies based upon legitimate contrasts which can be demonstrated empirically? To what extent do the value orientations of the theorists bias their results? How valuable are the dichotomies as guides to empirical investigation? To what extent do the dichotomous theories contribute to an understanding of the causes and directions of social change?

Species vary in the ease with which they can solve apparently similar problems. For instance, problems will be interpreted differently by different species due to differences such as how they process the world or their ecology. The latter is the focus of the ecological approach to cognition, which posits that ecology influences decision-making such that each species performs better on tasks that are naturally relevant to them. In a previous work, my colleagues and I compared the performance of cleaner fish and nonhuman primates, which differ substantially in brain size and ecology, on a dichotomous choice task derived from the cleaner fish ecology. In the task, subjects chose between two different plates, each containing a same food; if they chose the food from plate A, they could then choose the food from plate B as well, whereas if they chose B first, A was no longer available. Fish were better than primates at solving this task, emphasizing the role of ecology in shaping one species’ decision-making. For my dissertation project, I explored possible explanations for the primates’ poor performance in the task. In a first series of studies, I investigated the possibility that species differed in the task because of differences in the capacity to recognize the relevant cues (i.e. the plate design), to solve it. I thus repeated the task with fish and nonhuman primates, using variations designed to be more salient to primates. In a first experiment, the foods were different colors, whereas in a second experiment, they were hidden to avoid the prepotent response. In a second series of studies, I tested monkeys in a computerized paradigm that differed from the plate task by removing interaction with the human experimenter, which may be distracting, and providing a more standardized testing environment. Finally, in a last study, I investigated one possible cognitive limitation to the primates in the plate task, the failure to use backwards induction to solve it. These studies allowed me to investigate the role of ecology in species’ decision-making, a perspective that is often neglected in studies of cognition.

No description available.

The innate immune system is at the interface between the host's immune system and the initial contact with HIV. Understanding the correlates of innate immune protection against Human Immunodeficiency Virus is an important goal for development of effective anti-HIV therapies or vaccines. Not all exposures to HIV end in infection. The innate immune system has been linked to the reduced susceptibility of HIV-exposed seronegative (HESN) female commercial sex workers in Kenya by a number of studies. This thesis is a comparison of Toll-like receptor (TLR) responses in different immune cells in peripheral blood mononuclear cells (PBMCs) from HESN and HIV negative (susceptible) female commercial sex workers (CSWs). This study tested the hypothesis that higher TLR8 responsiveness in PBMCs of HESN to ssRNA analogous to HIV's genetic material, would result in higher effector responses capable of making HIV target cells more refractory in vitro, compared to susceptible controls. The results showed that PBMCs of HESN were often hypo-responsive to TLR4 and TLR7 stimulations evidenced by often reduced cytokine responses to the corresponding ligands, but hyper-responsive to TLR8 following stimulation with ssRNA analogous to HIV's genetic material. The 'dichotomy' in TLR responsiveness of HESN PBMCs was associated with differential expression of cognate TLRs in PBMCs, and altered activation of TLR signalling pathways. The opposing pattern of TLR7 and TLR8 responsiveness corresponded to the ability of HIV to infect target cells in vitro; where pre-treatment of PBMCs with TLR7 enhanced HIV replication whereas TLR8 stimulation inhibited HIV replication. The differences in outcomes of the HIV infection assays were associated with distinct cytokine profiles, where TLR7 stimulation induced robust type I IFNs responses without proinflammatory TNF-α and IL-12 cytokine responses,while TLR8 stimulations produced type II IFN responses accompanied by robust proinflammatory responses in both groups. The cytokine milieu of HESN PBMCs prior to and following TLR4 and TLR8 stimulations was more tightly regulated, but was associated with higher activation of CD8+, NK cells, monocytes but not blood DCs. These results demonstrate that the lower activation or 'quiescent' state of HESN PBMCs did not limit the ability of their cells to recognize ssRNA analogous to HIV derived genetic material and mount potent responses capable of limiting HIV infection in vitro, supporting the overall hypothesis tested. This thesis contributes to the growing knowledge on the dichotomous outcomes between TLR7 and TLR8 treatments with respect to HIV infection that could be instrumental in the design of novel HIV inventions such as vaccines or microbicides. / May 2016

This study investigated the effects of test length (10, 20 and 30 items), scoring schema (proportion of dichotomous ad polytomous scoring) and item analysis model (IRT and Rasch) on the ability estimates, test information levels and optimization criteria of mixed item format tests. Polytomous item responses to 30 items for 1000 examinees were simulated using the generalized partial-credit model and SAS software. Portions of the data were re-coded dichotomously over 11 structured proportions to create 33 sets of test responses including mixed item format tests. MULTILOG software was used to calculate the examinee ability estimates, standard errors, item and test information, reliability and fit indices. A comparison of IRT and Rasch item analysis procedures was made using SPSS software across ability estimates and standard errors of ability estimates using a 3 x 11 x 2 fixed factorial ANOVA. Effect sizes and power were reported for each procedure. Scheffe post hoc procedures were conducted on significant factos. Test information was analyzed and compared across the range of ability levels for all 66-design combinations. The results indicated that both test length and the proportion of items scored polytomously had a significant impact on the amount of test information produced by mixed item format tests. Generally, tests with 100% of the items scored polytomously produced the highest overall information. This seemed to be especially true for examinees with lower ability estimates. Optimality comparisons were made between IRT and Rasch procedures based on standard error rates for the ability estimates, marginal reliabilities and fit indices (-2LL). The only significant differences reported involved the standard error rates for both the IRT and Rasch procedures. This result must be viewed in light of the fact that the effect size reported was negligible. Optimality was found to be highest when longer tests and higher proportions of polytomous scoring were applied. Some indications were given that IRT procedures may produce slightly improved results in gathering available test information. Overall, significant differences were not found between the IRT and Rasch procedures when analyzing the mixed item format tests. Further research should be conducted in the areas of test difficulty, examinee test scores, and automated partial-credit scoring along with a comparison to other traditional psychometric measures and how they address challenges related to the mixed item format tests.

When an exam is administered across dual platforms, such as paper-and-pencil and computer-based testing simultaneously, individual items may become more or less difficult in the computer version (CBT) as compared to the paper-and-pencil (P&P) version, possibly resulting in a shift in the overall difficulty of the test (Mazzeo & Harvey, 1988). Using 38,955 examinees' response data across five forms of the National Nurse Aide Assessment Program (NNAAP) administered in both the CBT and P&P mode, three methods of differential item functioning (DIF) detection were used to detect item DIF across platforms. The three methods were Mantel-Haenszel (MH), Logistic Regression (LR), and the 1-Parameter Logistic Model (1-PL). These methods were compared to determine if they detect DIF equally in all items on the NNAAP forms. Data were reported by agreement of methods, that is, an item flagged by multiple DIF methods. A kappa statistic was calculated to provide an index of agreement bet ween paired methods of the LR, MH, and the 1-PL based on the inferential tests. Finally, in order to determine what, if any, impact these DIF items may have on the test as a whole, the test characteristic curves for each test form and examinee group were displayed. Results indicated that items behaved differently and the examinee's odds of answering an item correctly were influenced by the test mode administration for several items ranging from 23% of the items on Forms W and Z (MH) to 38% of the items on Form X (1-PL) with an average of 29%. The test characteristic curves for each test form were examined by examinee group and it was concluded that the impact of the DIF items on the test was not consequential. Each of the three methods detected items exhibiting DIF in each test form (ranging from 14 items to 23 items). The Kappa statistic demonstrated a strong degree of agreement between paired methods of analysis for each test form and each DIF method pairing (reporting good to excell ent agreement in all pairings). Findings indicated that while items did exhibit DIF, there was no substantial impact at the test level.

The relationship between Psychology and Theology has become an issue of increasing concern in recent years for the Christian community. With the growing complexities of cultural differences, the moral decline of society and its drift away from a Christian worldview, the pastoral ministry seems to be as challenging as ever. The problem about the relationship between theology and psychology is that there is growing confusion in today's Christian community about the best way to help people overcome their personal problems of living. In this regard some scholars believe that Christians should only submit to Biblical counselling, while others support psychotherapy, as long as it is integrated with Biblical principles and has a firm Scriptural foundation. In researching the literature on the subject, it was found that various theoretical models have been defined and described as attempts to scientifically justify the union of the above mentioned two points of view. In this thesis the viewpoints of four prominent groups of scholars about the subject are described and analysed in order to determine to what extent will it be possible to identify common denominators amongst their different models and to eventually establish if it is possible to formulate a synthesis about the commonalities so defined. The integration models of the following four prominent groups of authors about the subject were analysed: (1) Larry Crabb (1977); (2) William T. Kirwan (1993), (3) John D. 2 Carter & Bruce Narramore (1979) and (4) Eric L. Johnson & Stanton L. Jones, eds., (2000). These scholar's contributions were chosen for analysis because, from the research about the subject, it was found that these 4 groups of authors made some of the most significant scientific contributions about the integration of theology with psychology. Before attempting to formulate a pastoral paradigm out of a synthesis of the contributions of the aforementioned scholars, it was fundamentally important to distinguish between the 3 prominent views of man. Some scholars argue that man is a monistic being, while others defend a dichotomous view of man as consisting of a body and a soul. A third significant view describes man as consisting of three significant parts, namely a body, a soul and a spirit. In this thesis it was argued that the trichotomous view of man was the most correct way of defining the fundamental composition of man. According to the researcher an understanding of the trichotomous nature of man is important as it serves as a theological basis for pastoral counselling in order to clearly communicate the precise truths of the believer's union with Christ. In the last part of the thesis a practical pastoral paradigm was proposed based on the trichotomous view of man in which psychology and theology can be harmoniously integrated by means of a meta-systemic approach. The first phase of the paradigm focused on a model within which Psychotherapy can be applied while the second phase described Spirituotherapy as a model within which pastoral counselling can be applied. / Thesis (Ph.D. (Pastoral))--North-West University, Potchefstroom Campus, 2005.

The relationship between Psychology and Theology has become an issue of increasing concern in recent years for the Christian community. With the growing complexities of cultural differences, the moral decline of society and its drift away from a Christian worldview, the pastoral ministry seems to be as challenging as ever. The problem about the relationship between theology and psychology is that there is growing confusion in today's Christian community about the best way to help people overcome their personal problems of living. In this regard some scholars believe that Christians should only submit to Biblical counselling, while others support psychotherapy, as long as it is integrated with Biblical principles and has a firm Scriptural foundation. In researching the literature on the subject, it was found that various theoretical models have been defined and described as attempts to scientifically justify the union of the above mentioned two points of view. In this thesis the viewpoints of four prominent groups of scholars about the subject are described and analysed in order to determine to what extent will it be possible to identify common denominators amongst their different models and to eventually establish if it is possible to formulate a synthesis about the commonalities so defined. The integration models of the following four prominent groups of authors about the subject were analysed: (1) Larry Crabb (1977); (2) William T. Kirwan (1993), (3) John D. 2 Carter & Bruce Narramore (1979) and (4) Eric L. Johnson & Stanton L. Jones, eds., (2000). These scholar's contributions were chosen for analysis because, from the research about the subject, it was found that these 4 groups of authors made some of the most significant scientific contributions about the integration of theology with psychology. Before attempting to formulate a pastoral paradigm out of a synthesis of the contributions of the aforementioned scholars, it was fundamentally important to distinguish between the 3 prominent views of man. Some scholars argue that man is a monistic being, while others defend a dichotomous view of man as consisting of a body and a soul. A third significant view describes man as consisting of three significant parts, namely a body, a soul and a spirit. In this thesis it was argued that the trichotomous view of man was the most correct way of defining the fundamental composition of man. According to the researcher an understanding of the trichotomous nature of man is important as it serves as a theological basis for pastoral counselling in order to clearly communicate the precise truths of the believer's union with Christ. In the last part of the thesis a practical pastoral paradigm was proposed based on the trichotomous view of man in which psychology and theology can be harmoniously integrated by means of a meta-systemic approach. The first phase of the paradigm focused on a model within which Psychotherapy can be applied while the second phase described Spirituotherapy as a model within which pastoral counselling can be applied. / Thesis (Ph.D. (Pastoral))--North-West University, Potchefstroom Campus, 2005.

abstract: Long-term results of dietary weight loss interventions are not promising, with rates of weight loss maintenance at a mere 20%. Psychological factors related to weight maintenance include setting unrealistic weight goals, poor problem-solving skills, low self-efficacy, dichotomous thinking, and external locus of control. The ability to maintain a stable bodyweight over time has been associated with optimal health outcomes, lower stress levels, and higher general well-being. Dichotomous thinking has been associated with overeating and increased bodyweight. Cognitive restraint, disinhibition, and hunger are three dimensions of human eating behavior that appear to be important to understanding weight loss maintenance. Individuals who attempt to maintain their bodyweight via dietary restraint mechanisms are more susceptible to excessive eating episodes. Disinhibition has been found to be the strongest predictor of weight gain, while the research on the association between hunger and bodyweight is mixed. This study sought to evaluate the relationship between dichotomous thinking toward food and various eating behaviors (binge eating, cognitive restraint, disinhibition, and hunger). A multiple regression analysis revealed that binge eating, cognitive restraint, disinhibition, and hunger were each significant unique predictors of higher body mass index (BMI). Higher levels of hunger predicted lower BMI, controlling for cognitive restraint, disinhibition, and binge eating. Mediation analyses revealed that dichotomous thinking mediated the relationships between binge eating and BMI, cognitive restraint and BMI, and disinhibition and BMI. Further analysis revealed that binge eating mediated the relationship between dichotomous thinking and BMI, indicating that thinking of food in black-and-white could lead to higher rates of binge eating, and the excess calorie consumption could lead to increased BMI. The study findings suggest that a strong focus should be made to promote a more flexible attitude toward food in an effort to improve weight loss maintenance in the population. / Dissertation/Thesis / Masters Thesis Psychology 2018