• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 586
  • 99
  • 64
  • 44
  • 24
  • 22
  • 21
  • 15
  • 14
  • 7
  • 5
  • 4
  • 3
  • 3
  • 3
  • Tagged with
  • 1146
  • 199
  • 138
  • 90
  • 87
  • 81
  • 74
  • 67
  • 63
  • 63
  • 56
  • 56
  • 55
  • 50
  • 50
  • 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.
131

SMR neurofeedback training for cognitive enhancement : the mediating effect of SMR baseline levels

Pacheco, Berta January 2011 (has links)
In this study, 24 adults without any psychological or neurological disorders participated either in 10 neurofeedback training sessions to increase the amplitude of a frequency band between 12 and 15 Hz (sensorimotor rhythm - SMR) or in ten mock neurofeedback sessions. Pre and post training measures of memory and executive functions were completed, along with quantitative electroencephalography (QEEG) measurements in order to detect changes after the training course. Furthermore, measures of SMR amplitude were taken within and across sessions to determine whether self-regulation of SMR had been achieved. The data analysis performed shows no significant differences in cognitive performance between the group who underwent neurofeedback training and the group who underwent mock neurofeedback training. The groups did not show electrophysiological changes after the training. Additionally, no significant changes in SMR amplitude or percent time above threshold across or within the 10 sessions were found in the experimental group. Moreover, the data showed a tendency, which indicates that the higher the baseline amplitude and absolute power of SMR the less time was spent above threshold during the training and the less increase in SMR amplitude between baseline and training periods. The findings obtained indicate that neurofeedback training did not affect memory, executive functions or the QEEG. The absence of significant changes in SMR amplitude across sessions might reflect failure in learning the neurofeedback task and may account for the lack of cognitive improvement and QEEG changes. The fact that the ability to self-regulate SMR might be dependent on baseline amplitude has important implications in setting thresholds. Setting thresholds according to baseline levels might increase the difficulty in maintaining SMR above threshold when the baseline is higher. Future research should also address whether baseline amplitude has a predictive value in determining successful self-regulation of brain activity.
132

Application and refinement of cross-education strength training in stroke

Sun, Yao 25 September 2019 (has links)
Coordinated movements are regulated by the brain, spinal cord and sensory feedback. The interaction between the spinal cord and sensory feedback also play a significant role in facilitating plasticity and functional recovery after neural trauma. Cross-education describes training one side of the limb to enhance the strength of the homologous muscle on the contralateral side. Previous study with chronic stroke participants found significant strength gains in the more affected leg following unilateral dorsiflexion training on the less affected side, which suggested cross-education can be used to boost strength gain when training the more affected side is hard to initiate. However, there is lack of evidence showing cross-education in the arm muscles after stroke and the neural pathways mediating strength cross-education in stroke participants require further study. The modulatory role of sensory feedback in movement control has been studied by using cutaneous stimulation as a proxy of the sensory input from skin. Mechanistic studies on neurological intact participants show that cutaneous reflex pathways are widespread in the cervical and lumbar spinal cord and have a global effect on the muscles in the non-stimulated limbs. In rehabilitation training, sensory enhancement from prolonged electrical stimulation has been used to facilitate training outcomes for those had stroke and other neurological disorders. Therefore, cutaneous pathways may be important in regulating cross-education training-induced strength gain. The purpose of this dissertation was to explore the effects of upper limb cross-education strength training in chronic stroke participants and the role of sensory inputs in regulating intra- and interlimb neural excitability in neurologically intact participants. In the first project (Chapter 2), we explored the efficacy of cross-education strength training in wrist extensor muscles of chronic stroke participants. Strength improvements were found bilaterally with altered excitabilities in the cutaneous pathways on the untrained side. These results show the potential role of cutaneous pathways in mediating strength transfer after unilateral strength training which led us to further explore the factors may affect the cutaneous modulation. In neurologically intact participants, we investigated the effects forearm position (Chapter 4), stimulation trigger mode and parameters (Chapter 5) on the cutaneous reflexes in the stimulated limb. Following the findings from Chapter 3, 4, and 5, the interlimb effects of self-induced sensory enhancement on the cutaneous reflexes were examined in Chapter 6. Taken together, data from this thesis confirms the clinical application of cross-education in strength training after stroke. It addresses that exaggerated bilateral strength gains and neural plasticity can be induced following unilateral strength training on the less affected side. In addition, sensory enhancement may be applied to amplify cross-education effects in strength training. / Graduate / 2020-09-12
133

Mobile Enhancement of Motivation in Schizophrenia: A Pilot Trial of a Personalized Text-Message Intervention for Motivation Deficits

Lauren Luther (6685082) 16 October 2019 (has links)
<p>Motivation deficits remain an unmet treatment need in schizophrenia. Recent preclinical research has identified novel mechanisms underlying motivation deficits, namely impaired effort-cost computations and reduced future reward-value representation maintenance, that may serve as more effective treatment targets to improve motivation. The main aim of this study was to test the feasibility and preliminary effectiveness of a translational mechanism-based intervention, MEMS (Mobile Enhancement of Motivation in Schizophrenia), which leverages mobile technology to target these mechanisms with text-messages. Fifty-six participants with a schizophrenia-spectrum disorder were randomized to MEMS (<i>n</i> = 27) or a control condition (<i>n</i> = 29). All participants set recovery goals to complete over eight-weeks. The MEMS group also received personalized, interactive text-messages each weekday to support motivation. Retention and engagement in MEMS was high: 92.6% completed 8 weeks of MEMS, with an 86.1% text-message response rate, and 100% reported that they were satisfied with the text-messages. Compared to the control condition, the MEMS group had significantly greater improvements in interviewer-rated motivation and anticipatory pleasure and obtained significantly more recovery-oriented goals at the end of the 8-week period. There were no significant group differences in performance-based effort-cost computations and future reward-value representations, self-reported motivation, quality of life, functioning, or additional secondary outcomes of positive symptoms, mood symptoms, or neurocognition. Results suggest that MEMS is feasible as a relatively brief, low-intensity mobile intervention that could effectively improve interviewer-rated motivation, anticipatory pleasure, and recovery goal attainment in those with schizophrenia-spectrum disorders. </p>
134

Agrobiodiversity Enhancement for the sustainability of the tropical uplands: An evaluation of agricultural land use in Liliw, Laguna, Philippines

Wagan, Amparo M. January 2008 (has links)
Agrobiodiversity Enhancement (ABDE) is a strategy that has been advanced for preventing environmental degradation without losing agricultural productivity. However, there is not yet sufficient evidence to support the important role that ABDE might have for managing agricultural land use in the tropical uplands. This research is an attempt to help fill this knowledge gap. The general aim of the thesis was to explore the potential of ABDE as a management alternative for agricultural land use in the uplands in terms of environmental protection, productivity and farmer acceptability. To achieve the aim, a methodological framework for evaluating agricultural land use in the uplands was developed. The methodology aimed at allowing one to understand the influence of agricultural land use on natural resources and farm productivity and the social factors that will most likely influence land users to enhance agrobiodiversity of their production. The methodological framework provided a minimum set of criteria and indicators that can be used for assessing agricultural land uses in the uplands. Main criteria for the evaluation included protection, productivity, viability security and acceptability. The following indicators were included: Shannon Diversity Index, Depth of Topsoil, Soil Organic Matter, Soil Nitrate, Crop Yields, Net Income, Trend in Income and Harvest Loss, Farmer Traits, Farm Characteristics and Farmer perceptions on the influence of farming on the health of natural resources and of the farm workers. The methodological framework also includes a range of methods and techniques for gathering environmental, economic and social data in the uplands and indicates circumstances under which each might best be utilized. Using the methodological framework, agricultural land use in an upland area in Liliw, Laguna Philippines was evaluated for protection of natural resources, specifically of the soil quality and for farm productivity and for the social factors that influence the way agricultural lands are managed. Results showed integration of horticultural trees and crops have potential for protecting thickness of the topsoil, reducing nutrient wastage and is more economically profitable than monocropping systems. Specifically, coconut exhibited importance in maintaining thickness of topsoil while lanzones played major role in augmenting farm income and as buffer to income losses from annual crops. Older farmers and women were found associated with agricultural land use with diversified production in the case study area. The Logit model analysis further showed that leadership quality and land ownership are the social factors that will likely influence integration of horticultural trees and crops in the uplands. Other personal characteristics like years of experience in farming, access to other sources of livelihood, land size, awareness of land degradation and effect of agrochemicals on heath of the farm workers have no likely influence on agricultural lands with integration of horticultural trees and crops. SWOT analysis of agricultural land use in the case study site showed that despite the environmental and economic advantages of agricultural lands with diversified production, there are weaknesses and barriers to its further development and implementation. From this assessment, implications for developing and implementing an ABDE intervention program for the tropical uplands were drawn.
135

Preparation of Stable Gold Colloids for Sensitivity Enhancement of Progesterone Immunoassay using Surface Plasmon Resonance

Wu, Kevin Su-Wei January 2007 (has links)
The purpose of this study was to prepare concentrated and stable gold colloids for the enhancement of the signal response of the SPR technique for detecting small molecules such as progesterone. The gold colloids developed in this study were prepared by hydrazine hydrate, sodium borohydride, and tri-potassium citrate reduction routes. The study revealed that the sodium borohydride reduced gold colloids were extremely stable and it was able to be utilised in the progesterone immunoassay developed previously by Mitchell et al. The experiment was carried out on BIAcore 3000 using two different sensor surfaces (CM5 and SAM). The results showed that the enhancement species prepared from the borohydride-reduced gold colloids were able to improve the SPR signal response by 13 times higher than SPR signal produced without the enhancement species on the CM5 surface. The signal enhancement on the SAM surface using the same enhancement species was even greater at 29 times higher. The sensitivity of the assay was, however, unable to be determined due to time constraint. The limit of detection (LOD) of the progesterone assay using the CM5 chip was estimated to be ca. 5-20 pg/mL. Whilst for the SAM chip, the LOD of the progesterone assay was estimated to be ca. 5-20 fg/mL. Further work is required to confirm these estimated LOD values.
136

Grain Reduction in Scanned Image Sequences under Time Constraints

Stuhr, Lina January 2009 (has links)
<p>This thesis is about improving the image quality of image sequences scanned by the film scanner GoldenEye. Film grain is often seen as an artistic effect in film sequences but scanned images can be more grainy or noisy than the intention. To remove the grain and noise as well as sharpen the images a few known image enhancement methods have been implemented, tested and evaluated. An own idea of a thresholding method using the dyadic wavelet transform has also been tested. As benchmark has MATLAB been used but one method has also been implemented in C/C++. Some of the methods works satisfactory when it comes to the image result but none of the methods works satisfactory when it comes to time consumption. To solve that a few speed up ideas are suggested in the end of the thesis. A method to correct the color of the sequences has also been suggested.</p>
137

Enhancement and Visualization of VascularStructures in MRA Images Using Local Structure

Esmaeili, Morteza January 2010 (has links)
<p>The novel method of this thesis work is based on using quadrature filters to estimate an orientation tensor and to use the advantage of tensor information to control 3D adaptive filters. The adaptive filters are applied to enhance the Magnetic Resonance Angiography (MRA) images. The tubular structures are extracted from the volume dataset by using the quadrature filters. The idea of developing adaptive filtering in this thesis work is to enhance the volume dataset and suppress the image noise. Then the output of the adaptive filtering can be a clean dataset for segmentation of blood vessel structures to get appropriate volume visualization.</p><p>The local tensors are used to create the control tensor which is used to control adaptive filters. By evaluation of the tensor eigenvalues combination, the local structures like tubular structures and stenosis structures are extracted from the dataset. The method has been evaluated with synthetic objects, which are vessel models (for segmentation), and onion like synthetic object (for enhancement). The experimental results are shown on clinical images to validate the proposed method as well.</p>
138

Improving visualisation of bronchi in three-dimensional rendering of CT data

Köpsén, Kristian January 2007 (has links)
<p>The medical imaging system Sectra PACS from Sectra Imtec contains a 3D mode that can be used for visualising image stacks from e.g. computed tomography. Various structures of human anatomy can be visualised in the 3D mode, but visualisations of the bronchial tree of the lungs rarely become good enough to be useful. The goal of this work was to investigate ways of improving such visualisations.</p><p>Various approaches were studied, evaluated and tested. The fact that most effort was needed for small structures with sizes similar to the resolution of the images made things slightly more complicated. A method classifying neighbourhoods based on local structure emerged as most promising, and was used as foundation for a proposed algorithm. It creates a mask representing the presence of bronchi, allowing the hiding of uninteresting structures in its proximity. The algorithm was then implemented so that it could be tested together with the existing system.</p><p>The method was found to work well and was able to detect the smaller tubes of the bronchial tree and output the desired classification mask. Its usefulness was somewhat reduced by issues relating to speed, and the fact that many computed tomography image stacks lack the necessary resolution for visualising the finer details of the bronchial tree.</p>
139

Påverkan av social desirability vid självskattning av könstereotypa egenskaper för män och kvinnor

Karlsson, Christina January 2007 (has links)
<p>Studiens syfte var att undersöka om det sker en social desirability effekt vid självskatting av egenskaper som beskriver manliga och kvinnliga stereotyper när dessa egenskaper framhävs positivt. Studien ämnade ytterligare undersöka om män och kvinnor skiljer sig åt i social desirability. Ett experiment utfördes där försökspersonerna slumpvis fördelades över en kontrollbetingelse och två experimentbetingelser. Den ena experimentbetingelsen tilldelades en kvinnlig manipulation där kvinnliga stereotyper framhävdes positivt medan den andra experimentbetingelsen tilldelades en manlig manipulation där manliga stereotyper framhävdes positivt. Kontrollbetingelsen tilldelades ingen manipulation. Därefter fick försökspersonerna skatta sig själva på påståenden i en enkät som beskrev de könstereotyperna som angivits i de båda manipulationerna. Ingen social desirability effekt uppvisades i resultatet.</p>
140

The Double-Edged Sword of Self-Enhancement: A Longitudinal Examination of the Effects of Self-Enhancement on Psychological and Physical Well-Being among Individuals with Multiple Sclerosis

O'Mara, Erin Marie 01 August 2011 (has links)
The present study prospectively examines factors that affect whether self-enhancement exerts favorable or unfavorable effects on both psychological and physical well-being in a context that is less controllable than other contexts in which self-enhancement has been examined (e.g., academic performance), an at risk population of Multiple Sclerosis (MS) patients. In particular, the present study (a) examines whether self-enhancement differentially predicts psychological and physical well-being when self-enhancement is related or unrelated to the well-being outcomes, and (b) whether self-enhancement interacts with severity of circumstances (i.e., course of MS) to predict psychological and physical well-being, as suggested by O’Mara, McNulty, & Karney (2011). In addition to the baseline assessment, participants completed measures of self-enhancement (outcome-related and outcome-unrelated), and psychological and physical well-being every 30 days for 90 days, for a total of four assessments. The pattern of findings suggests that in less controllable contexts, self-enhancement is a doubled-edged sword. Outcome-related self-enhancement was trending towards a positive, cross-sectionally association with physical well-being, and a measure of prior outcome-unrelated self-enhancement (collectivistic tactical self-enhancement) was positively associated with subsequent physical well-being only for individuals with less severe MS. Further, prior outcome-related self-enhancement was associated with better subsequent psychological well-being but worse subsequent physical well-being, and although prior collectivistic tactical self-enhancement is associated with favorable subsequent physical well-being for individuals with less severe MS, it is also associated unfavorable psychological well-being regardless of MS severity. The discussion addresses the contributions of the present study to the literature, strengths and limitations of the present study, and directions for future research.

Page generated in 0.0711 seconds