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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

The Neuroethical Case Against Cognitive Memory Manipulation

DePergola, Peter Angelo, II 17 May 2016 (has links)
An increasingly blurred understanding of the moral significance of accurate and authentic memory reconsolidation for an adequate apprehension of self, other, and community suggests a critical need to explore the inter-relationships shared between autobiographical memory, emotional rationality, and narrative identity in light of the contemporary possibilities of neurocognitive memory manipulation, particularly as it bears on ethical decision making. Grounding its thesis in four evidential effects – namely, (i) neurocognitive memory manipulation disintegrates autobiographical memory, (ii) the disintegration of autobiographical memory degenerates emotional rationality, (iii) the degeneration of emotional rationality decays narrative identity, and (iv) the decay of narrative identity disables one to seek, identify, and act on the good – the dissertation argues that neurocognitive memory manipulation cannot be justified as a morally licit biomedical practice insofar as it disables one to seek, identify, and act on the good. / McAnulty College and Graduate School of Liberal Arts; / Health Care Ethics / PhD; / Dissertation;
32

Predictors of Hiv-related Neurocognitive Impairment in an Hiv/aids Population

Steinberg, Tara, C. 08 1900 (has links)
Although, in the United States HIV infectivity has increased, survival rates have also improved due to highly active antiretroviral therapies (HAART). Adherence to HAART successfully prevents the progression of AIDS and AIDS-related morbidity for many living with HIV. Unfortunately, HAART’s permeability into the central nervous system (CNS) is limited; thus, the prevalence of HIV-associated neurocognitive disorders (HAND) still persists. The health belief model (HBM) is the theory often used to explain and predict behavior in relation to chronic illness. This model incorporates perceptions of susceptibility, vulnerability, and severity towards a particular illness, and beliefs regarding perceived efficacy and benefits of treatment. This study expands the existing model. Many who live with HIV have a long history of negative experiences, such as stigmatization, traumatic events, and discrimination. I examined supplementary psychosocial and physiological predictor variables, such as stigma, trauma, ethnicity, general medical conditions, HIV-opportunistic infections, and falls; all relevant to disease progression in HIV. Previous researchers found links between stigma and immune function, trauma and memory, ethnicity and neuropsychological impairment, and symptom load and CNS-related alterations. Therefore, this study examined how these different psychosocial predictor variables are associated with HIV-related neurocognitive impairment. My model explained 38.6% of the variance in the outcome variable, and I found that trauma (B = -.15, OR = .87; CI 95% = .75, 1.0, p = .05), ethnicity (B = 2.2, OR = 9.0, CI 95% = 1.68, 48.48, p =.01), general medical conditions (B = .30, OR = 1.34; CI 95% = 1.0, 1.81, p = .05), and falls (B = 2.0, OR = 7.2; CI 95% = 1.1, 47.0, p = .04), were all significant predictors of HIV-related neurocognitive impairment. However, contrary to my hypothesis, HIV-related opportunistic infections and HIV-related stigma were not significant predictors of HIV-related neurocognitive impairment. I hope that my results will contribute to revisions of older health models as well as suggest avenues for primary and secondary prevention and intervention to address those living with HIV/AIDS.
33

Exploration of Energy Efficient Hardware and Algorithms for Deep Learning

Syed Sarwar (6634835) 14 May 2019 (has links)
<div>Deep Neural Networks (DNNs) have emerged as the state-of-the-art technique in a wide range of machine learning tasks for analytics and computer vision in the next generation of embedded (mobile, IoT, wearable) devices. Despite their success, they suffer from high energy requirements both in inference and training. In recent years, the inherent error resiliency of DNNs has been exploited by introducing approximations at either the algorithmic or the hardware levels (individually) to obtain energy savings while incurring tolerable accuracy degradation. We perform a comprehensive analysis to determine the effectiveness of cross-layer approximations for the energy-efficient realization of large-scale DNNs. Our experiments on recognition benchmarks show that cross-layer approximation provides substantial improvements in energy efficiency for different accuracy/quality requirements. Furthermore, we propose a synergistic framework for combining the approximation techniques. </div><div>To reduce the training complexity of Deep Convolutional Neural Networks (DCNN), we replace certain weight kernels of convolutional layers with Gabor filters. The convolutional layers use the Gabor filters as fixed weight kernels, which extracts intrinsic features, with regular trainable weight kernels. This combination creates a balanced system that gives better training performance in terms of energy and time, compared to the standalone Deep CNN (without any Gabor kernels), in exchange for tolerable accuracy degradation. We also explore an efficient training methodology and incrementally growing a DCNN to allow new classes to be learned while sharing part of the base network. Our approach is an end-to-end learning framework, where we focus on reducing the incremental training complexity while achieving accuracy close to the upper-bound without using any of the old training samples. We have also explored spiking neural networks for energy-efficiency. Training of deep spiking neural networks from direct spike inputs is difficult since its temporal dynamics are not well suited for standard supervision based training algorithms used to train DNNs. We propose a spike-based backpropagation training methodology for state-of-the-art deep Spiking Neural Network (SNN) architectures. This methodology enables real-time training in deep SNNs while achieving comparable inference accuracies on standard image recognition tasks.</div>
34

Avaliação neuropsicológica de pacientes obesos pré e pós cirurgia bariátrica / Neuropsychological evaluation of obese patients before and after bariatric surgery

Meghelli, Bruna Lopes 05 April 2019 (has links)
Observa-se um desempenho cognitivo abaixo da média na população obesa. A cirurgia bariátrica e a consequente perda de tecido adiposo parecem ter efeitos positivos sobre o funcionamento cognitivo. Objetivo: Avaliar o desempenho cognitivo e o estado nutricional do paciente pré e pós cirurgia bariátrica Metodologia: Foram incluídos 22 pacientes do ambulatório de Cirurgia Bariátrica do HCFMRP-USP, que foram submetidos à avaliação neuropsicológica composta de testes psicológicos de atenção, memória e velocidade de processamento de informação em dois momentos: período pré-cirúrgico (1 a 2 dias antes da cirurgia bariátrica) e pós cirúrgico (de 6 a 12 meses). A avaliação do estado nutricional foi feita a partir de exames coletados rotineiramente pela equipe, em períodos pré e pós-cirúrgico. Os dados obtidos foram comparados entre os períodos pré e pós e analisados estatisticamente. Resultados: A perda de excesso de tecido adiposo e a melhora no estado nutricional do paciente foi acompanhada de uma melhora no desempenho cognitivo. Observouse melhora no desempenho da atenção para o cartão 2 do teste Stroop e da velocidade de processamento para os subtestes Códigos e Procurando Símbolos no teste WAIS. Houve redução de ferritina, gama GT, ácido úrico, proteínas totais e triglicérideos e aumento de ácido fólico sérico, volume corpuscular médio, HDL. Conclusão: Este estudo sugere que a cirurgia bariátrica tem como efeito a melhora no desempenho cognitivo. Observam-se alguns indícios de que a diminuição dos marcadores de processo inflamatório pode estar correlacionada com a melhora cognitiva dos pacientes. A melhora do desempenho, no entanto, não foi suficiente para atingir a média da população. O estado nutricional, apesar de ter sofrido alterações, foi considerado estável clinicamente / It was observed that the obese population is more likely to present cognitive impairment. Bariatric surgery and its consequently lost of adipose tissue seems like to have positive effects in cognitive performance. Objective: Evaluate the patient´s cognitive performance and his nutritional aspects before and after bariatric surgery. Methodology: 22 patients from Bariatric Surgery Service HCFMRP-SP were included. The neuropsychological evaluation was composed by psychological tests (attention, memory and information processing), and it was applied in two moments: preoperative (1-2 days before surgery) and pos surgery (6-12 months). The exams for the nutritional assessment were collected before and after bariatric surgery. The data were compared and analyzed. Results: Cognitive improvment in attention was observed in card 2 Stroop test and in information processing in the subtests Coding and Simbol Searching, from WAIS test. There was a reduction in ferritin, GT Gama, uric acid, total proteins and triglycerides and increase in serum folic acid, mean corpuscular volume, HDL. Conclusão: Bariatric surgery improve cognitive performance. Increase in inflamatory markers may be relates with cognitve improvment. However, the group did\'nt reach médium average after bariatri surgery. The group was considered clinically stable for the nutritional changes
35

Multiple sports concussion in male rugby players : a neurocognitive and neuroimaging study

Woollett, Katherine January 2017 (has links)
Objective: Following a sport related concussion (SRC) visible symptoms generally dissipate in 7-10 days post-injury. However, little is known about the cumulative effects of SRCs both in terms of structural damage to the white matter of the brain and neurocognitive performance. To address this issue, the relationship between the number of SRCs (frequency), axonal white matter (WM) damage and neurocognitive performance was examined. There were three predictions. First, increases in SRC frequency will be associated with decreases in performance on neurocognitive tests. Second, the frequency of SRC will be associated with axonal injury measured three WM tracts: the corpus callosum, the fronto-occipital fasciculus and the inferior longitudinal fasciculus. Third, less accurate and slower performance on a response inhibition task (STOP-IT) will be associated with greater axonal injury. Methods: A cross-sectional correlational design was utilised. Participants were rugby players with a history of SRC, rugby players with no history of SRC and control athletes (N=40) who completed a neurocognitive test battery and had a DTI brain scan. The neurocognitive battery consisted of the following standardised tests: Speed and Capacity of Language Processing Test, CogState Electronic Battery, Stroop Colour and Word Test, Controlled Oral Word Association Test, the Trail Making Test and the experimental test STOP-IT Electronic Test. White matter axonal injury was measured by DTI using fractional anisotropy (FA) and mean diffusivity (MD) metrics. The DTI data was processed using FSL to extract FA and MD DTI metrics in three a-priori regions of interest. Results: Spearman’s correlation analyses did not find significant associations between SRC frequency and neurocognitive performance on the FAS (rs=0.053, 95% CI [-0.27, 0.36]), TMT-A (rs=0.058, 95% CI [-0.26, 0.37]), TMT-B (rs= -0.046, 95% CI [-0.27, 0.36]) and the Stroop Interference (rs= -0.25, 95% CI [-0.07, 0.52]). Similarly, no significant Spearman’s correlations were found between SRC frequency and the computerised neurocognitive tests STOP-IT-SSRT (rs= -0.04, 95% CI [-0.28, 0.35])), STOP-IT–Accuracy (rs= -0.05, 95% CI [-0.27, 0.36]), CogState Detection subtest (rs= -0.15, 95% CI [-0.17, 0.44]), CogState Identification subtest (rs= -0.065, 95% CI [-0.26, 0.37]), CogState One card learning subtest (rs= 0.24, 95% CI [-0.08, 0.52]) or the CogState One back task subtest (rs= 0.06, 95% CI [-0.26, 0.37]). In terms of the DTI data there were no significant associations between SRC frequency and axonal injury measured by FA values in the CC (rs= 0.005, 95% CI [-0.31, 0.32]), ILF (rs= 0.028, 95% CI [-0.29, 0.34]) or FOF (rs= -0.022, 95% CI [-0.30, 0.33]). The same was pattern was found for MD values in the CC (rs= 0.081, 95% CI [-0.24, 0.39]), ILF (rs= -0.16, 95% CI [-0.16, 0.45]) or FOF (rs= -0.15, 95% CI [-0.17, 0.44]) Finally, there were no significant Spearman’s correlations between axonal injury FA values and the STOP-IT SSRT in any of the ROIs: CC (rs= 0.005, 95% CI [-0.31, 0.32]), ILF (rs= 0.028, 95% CI [-0.29, 0.34]) or FOF (rs= -0.022, 95% CI [-0.30, 0.33]). Equally, there were no significant correlations between MD values STOP-IT SSRT in the CC (rs= -0.028, 95% CI [-0.29, 0.34]), ILF (rs= -0.16, 95% CI [-0.16, 0.45]) or FOF (rs= -0.15, 95% CI [-0.17, 0.44]). Likewise, there were no significant Spearman’s correlations between accuracy on the STOP-IT and FA values and in any of the ROIs: CC (rs= 0.19, 95% CI [-0.13, 0.48]), ILF (rs= -0.045, 95% CI [-0.27, 0.35]) and FOF (rs= -0.032, 95% CI [-0.29, 0.34]), or MD values in the CC (rs= -0.11, 95% CI [-0.21, 0.41]), ILF (rs= 0.017, 95% CI [-0.30, 0.33]) or FOF (rs= 0.082, 95% CI [-0.24, 0.39]). This study did not find support for the hypothesis that cumulative SRCs are associated with poorer performance on neurocognitive tests or with axonal injury as measured by FA and MD DTI metrics. Conclusion: The null findings suggest that there are no cumulative effects of SRCs. The current findings are inconsistent with previous cross-sectional research that indicates that there are long-term changes to diffusivity measures present after single SRCs as well as cumulative effects in contact sport athletes. Likewise they are at odds with evidence suggesting that after three SRCs neurocognitive performance can be affected. The study needs to be extended to include a larger sample to ensure the results are not due to low statistical power.
36

Computational modelling and assessment of depression : from neutral mechanisms and etiology to measurable behaviour

Stolicyn, Aleksej January 2018 (has links)
Depression is a highly prevalent clinical condition which has been estimated to affect a growing part of the population in western countries. Alongside expenditure on diagnostics and treatment, there is a high economic impact due to lost productivity. Although a range of treatments are available, diagnoses are currently costly and require subjective assessment by a specialist. Moreover, treatment selection can be lengthy and can involve trial and error. To develop better diagnostics, stratification, and treatments for depression, we need a better understanding of the condition across different levels - from neural mechanisms to cognition and behaviour. Computational modelling is an emergent theory-driven approach which can aid linking data across different levels of analysis - from neural mechanisms and computations in the brain, to cognitive algorithms and observable behaviour. Some models integrate diverse findings and make predictions, while others enable inference of clinical measures which are not obvious in raw data. Modelling can lead to better understanding of depression, and in turn to better stratification and treatments. On the other hand, machine learning and classification methods can help detect clinically-relevant patterns in experimental data in a purely data-driven manner. This can lead to development of better screening and diagnostic methods. In the current work, we first review some of the most prominent neurocognitive theories of depression, as well as existing studies which used computational modelling methods. Based on our review, we argue that modelling can provide a rich set of tools for a better understanding of the condition. We then develop two novel computational modelling accounts of depression. In the first account, we propose an explicit mechanistic link between a robust behavioural negative bias effect and some of the widely reported or theorised neural aspects of depression - hyperactive amygdala and inhibited dopamine release. In the second account, we attempt to better explain depressive cognitive deficits and show how they can arise from depression-relevant etiological factors - altered valuation and controllability estimates. Finally, in the third part of this work we attempt to develop a novel system for detecting depressive symptoms based on a combination of face-tracking, eye-tracking and cognitive performance measures. We evaluate the system in a pilot experiment and show that a combination of measures can achieve better results than measures from each domain separately.
37

Association between structural measures of specific regional brain volumes measured by quantitative magnetic resonance imaging and neurocognitive performance in elderly breast cancer survivors exposed to chemotherapy

Hamsakutty, Haris 01 December 2009 (has links)
Recent advances in early detection and treatment of breast cancer have led to increasing numbers of long term survivors of breast cancer. There is a growing concern about the potential adverse effects of chemotherapy on cognitive functioning. The current study examines the neuroanatomical correlates of late neurocognitive effects of chemotherapy in elderly breast cancer survivors who have survived more than ten years and were exposed to chemotherapy at the time of their cancer treatment. The participants in this study are 30 women breast cancer survivors in the age range of 65-81 years. In this cross sectional design, regional brain volumes measured using magnetic resonance imaging were correlated with cognitive test scores using multiple regression analyses. The test scores from Wisconsin Card Sorting Test and Trail Making Test B are used as measures of executive function. The test scores from the Letter Number Sequencing subset of the Wechsler Adult Intelligence Scale (WAIS) are used for measures of working memory. We found support for the hypothesized association between reduction in performance on specific neuropsychological tests and reduced volumes predominantly in the frontal, temporal and subcortical white matter regions. These results suggest that the frontal, temporal and subcortical white matter region are a neuroanatomical correlate of cognitive impairment seen in our study population. Future research will be needed to discern whether the structural correlates of cognitive impairment seen in long term cancer survivors is likely to be developed as an imaging marker for cognitive evaluation and rehabilitation.
38

Biocompatible circuits : inflammation and soluble adhesion molecules after cardiopulmonary bypass

Marcoux, Jo-Anne Éloria 11 July 2011
ABSTRACT In the modern era, the most common post-operative complications following cardiopulmonary bypass (CPB) are neurocognitive deficits (NCD) and atrial fibrillation (AF). Both morbidities have been linked to inflammation resulting from surgery, anesthesia and CPB. Microemboli, inadequate oxygen delivery and the inflammatory response consequent to blood contacting artificial components of the CPB circuit have all been linked to postoperative NCD and to a lesser extent post-operative AF. The artificial components of the CPB circuit consist of stainless steel, polyvinylchloride (PVC), polycarbonate and other carbon-based plastics. In order to attenuate the negative sequelae of blood-circuit contact related inflammatory response, industry developed the biocompatible circuit (BCC) coating for the disposable CPB circuits. Four such coatings were studied and compared to an uncoated control group in a total of 101 patients undergoing routine CPB-assisted cardiac surgical procedures. Soluble adhesion molecule (SAM) activation was studied at different time points and common clinical outcomes such as white blood cell activation, serum renal function parameters urea and creatinine, postoperative bleeding, transfusion requirements, intensive care and hospital length of stay, CPB pump volume balances, changes in weight, postoperative serum lactate and glucose and the development of AF postoperatively, were compared. Additionally, postoperative neurocognitive testing was performed using a simple bedside neurocognitive test called the antisaccadic eye movement test. The patients in all groups were tested for comparison preoperatively and 72 hr postoperatively. Results: The mandate of BCC coating development and manufacture is to attenuate the well-documented and demonstrated inflammatory response consequent to the contact of blood with artificial CPB surfaces. The studied BCCs significantly decreased platelet transfusions in females. In addition, the BCCs decreased the concentrations of 2 SAMs when measured 6 hours after surgery and CPB. The difference in SAM expression seen between the coated and uncoated groups at 6 hr was no longer apparent at 72 hr. Very little difference was noted between the four BCC groups. Patients who developed AF postoperatively seemed predisposed to do so as the serum levels of soluble vascular cell adhesion molecule was significantly higher at baseline and remained so at 6 and 72 hr. The decreased platelet transfusions in females resulting from BCC use is a highly significant finding within this high-risk group of patients. As most platelet transfusions occur soon after the patient is disconnected from CPB, the short-term decrease in SAM activation can be linked to this improved clinical finding. The studied BCC coatings have achieved limited success in their intended mandate to attenuate inflammatory response in terms of improved clinical and laboratory desired outcomes.
39

Biocompatible circuits : inflammation and soluble adhesion molecules after cardiopulmonary bypass

Marcoux, Jo-Anne Éloria 11 July 2011 (has links)
ABSTRACT In the modern era, the most common post-operative complications following cardiopulmonary bypass (CPB) are neurocognitive deficits (NCD) and atrial fibrillation (AF). Both morbidities have been linked to inflammation resulting from surgery, anesthesia and CPB. Microemboli, inadequate oxygen delivery and the inflammatory response consequent to blood contacting artificial components of the CPB circuit have all been linked to postoperative NCD and to a lesser extent post-operative AF. The artificial components of the CPB circuit consist of stainless steel, polyvinylchloride (PVC), polycarbonate and other carbon-based plastics. In order to attenuate the negative sequelae of blood-circuit contact related inflammatory response, industry developed the biocompatible circuit (BCC) coating for the disposable CPB circuits. Four such coatings were studied and compared to an uncoated control group in a total of 101 patients undergoing routine CPB-assisted cardiac surgical procedures. Soluble adhesion molecule (SAM) activation was studied at different time points and common clinical outcomes such as white blood cell activation, serum renal function parameters urea and creatinine, postoperative bleeding, transfusion requirements, intensive care and hospital length of stay, CPB pump volume balances, changes in weight, postoperative serum lactate and glucose and the development of AF postoperatively, were compared. Additionally, postoperative neurocognitive testing was performed using a simple bedside neurocognitive test called the antisaccadic eye movement test. The patients in all groups were tested for comparison preoperatively and 72 hr postoperatively. Results: The mandate of BCC coating development and manufacture is to attenuate the well-documented and demonstrated inflammatory response consequent to the contact of blood with artificial CPB surfaces. The studied BCCs significantly decreased platelet transfusions in females. In addition, the BCCs decreased the concentrations of 2 SAMs when measured 6 hours after surgery and CPB. The difference in SAM expression seen between the coated and uncoated groups at 6 hr was no longer apparent at 72 hr. Very little difference was noted between the four BCC groups. Patients who developed AF postoperatively seemed predisposed to do so as the serum levels of soluble vascular cell adhesion molecule was significantly higher at baseline and remained so at 6 and 72 hr. The decreased platelet transfusions in females resulting from BCC use is a highly significant finding within this high-risk group of patients. As most platelet transfusions occur soon after the patient is disconnected from CPB, the short-term decrease in SAM activation can be linked to this improved clinical finding. The studied BCC coatings have achieved limited success in their intended mandate to attenuate inflammatory response in terms of improved clinical and laboratory desired outcomes.
40

Influence of Maternal Thyroid Dysfunction on Infant Growth and Development

Wilson, Ronee Elisha 01 January 2013 (has links)
Thyroid dysfunction is one of the most common endocrine disorders in women of childbearing age and the obstetric consequences of abnormal thyroid hormone levels during pregnancy have been established. Less understood is the implication of the presence of maternal thyroid autoantibodies on infant outcomes among women who are euthyroid during pregnancy. The objective of this study was two-fold: 1) to examine the influence of antenatal thyroperioxidase (TPO) status on fetal/infant brain and body growth measurements at delivery and 2) to explore the relationship of antenatal TPO status and maternal postpartum thyroid dysfunction (PPTD) on early infant growth and neurocognitive development. Six-hundred thirty-one (631) euthyroid pregnant women were recruited from prenatal clinics in Tampa Bay, Florida and the surrounding area between November 2007 and December 2010. TPO status was determined during pregnancy and fetal/infant brain and body growth variables were assessed at delivery. A subsample of forty-one (41) mother-infant dyads participated in a 6-month longitudinal supplemental study. Infant growth assessments were conducted at 3, 4, 5 and 6 months postpartum. Regression analysis revealed maternal TPO positivity was significantly associated with smaller head circumference, reduced brain weight and lower brain-body-ratio; however maternal race/ethnicity was identified as an effect modifier in the relationship. No significant differences were noted in birth weight, birth length, abdominal circumference or chest circumference measurements among infants born to TPO positive mothers of any racial/ethnic group as compared to their negative counterparts. Mixed model analysis of the smaller subset (n=41) revealed infants of TPO+ mothers were smaller at birth but experienced accelerated growth between birth to 3 months when compared to infants born to TPO- mothers. This acceleration led to their catch-up in growth to their TPO negative counterparts by 3 months of age. No significant differences were noted in neurocognitive outcomes between infants born to TPO+ mothers compared to those born to TPO- mothers. The findings in this dissertation indicate that maternal/race ethnicity modifies the relationship between TPO positivity and reduced fetal/infant brain growth. Additionally, the analyses suggest that maternal autoantibody status could lead to variations in early infant growth and development. The end-result of these variations is unclear. Further research is needed to determine the potential impact of reduced head circumference and accelerated growth as it relates to long-term neurocognitive consequences. Currently, TPO antibody status is not assessed as part of the standard prenatal care laboratory work-up, but findings from this study suggest that fetal brain growth may be impaired by TPO positivity among certain populations, therefore autoantibody screening among high-risk sub-groups may be useful for clinicians to determine whether prenatal thyroid treatment is warranted.

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