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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.
371

Imidazole-Containing Polymerized Ionic Liquids for Emerging Applications: From Gene Delivery to Thermoplastic Elastomers

Allen, Michael H. Jr. 07 January 2013 (has links)
Novel imidazole-containing polyelectrolytes based on poly(1-vinylimidazole) (poly(1VIM)) were functionalized with various hydroxyalkyl-substituents to investigate the influence of charge density and hydrogen bonding on nonviral DNA delivery.  Copolymers with higher charge densities exhibited increased cytotoxicity, whereas increased hydroxyl concentrations remained nontoxic.  DNA binding affinity increased with increased charge densities and increased hydroxyl content.  Dynamic light scattering determined the copolymers which delivered DNA most effectively maintained an intermediate binding affinity between copolymer and DNA.  Copolymers containing higher charge densities or hydroxyl concentrations bound DNA too tightly, preventing its release inside the cell.  Copolymers with lower charge densities failed to protect the DNA from enzymatic degradation.  Tuning hydrogen bonding concentration allowed for a less toxic and more effective alternative to conventional, highly charged polymers for the development of nonviral DNA delivery vehicles.  The synthesis of amine-containing imidazolium copolymers functionalized with low concentrations of folic acid enabled the investigation of additional polymer modifications on nonviral gene delivery.   Functionalization of 1VIM with various hydroxyalkyl and alkyl groups and subsequent conventional free radical polymerization afforded a series of imidazolium-containing polyelectrolytes.  Hydroxyl-containing homopolymers exhibited higher thermal stabilities and lower T<sub>g</sub>'s compared to the respective alkyl-analog.  X-ray scattering demonstrated the polarity of the hydroxyl group facilitated solvation of the electrostatic interactions disrupting the nanophase-separated morphology observed in the alkylated systems.  Impedance spectroscopy determined hydroxyl-containing imidazolium homopolymers displayed higher ionic conductivities compared to the alkyl-containing analogs which was attributed to increased solvation of electrostatic interactions in the hydroxyl analogs. Beyond functionalizing 1VIM monomers and homopolymers to tailor various properties, the synthesis of novel architectures in a controlled fashion remains difficult due to the radically unstable N-vinyl propagating radical.  The regioisomer 4-vinylimidazole (4VIM) contains two resonance structures affording increased radical stability of the propagating radical.  Nitroxide-mediated polymerization (NMP) and atom transfer radical polymerization (ATRP) failed to control 4VIM homopolymerizations; however, reversible addition-fragmentation chain transfer (RAFT) demonstrated unprecedented control.  Linear pseudo-first order kinetics were observed and successful chain extension with additional 4VIM suggested preservation of the trithiocarbonate functionality. Effectively controlling the polymerization of 4VIM enabled the design of amphoteric block copolymers for emerging applications.  The design of ABA triblock copolymers with 4VIM as a high T<sub>g</sub> supporting outer block and di(ethylene glycol) methyl ether methacrylate (DEGMEMA) as a low T<sub>g</sub>, inner block, required the development of a new difunctional RAFT chain transfer agent (CTA).  The difunctional CTA successfully mediated the synthesis of the ABA triblock copolymer, poly(4VIM-b-DEGMEMA-b-4VIM), which exhibited microphase separated morphologies.  The amphoteric nature of the imidazole ring required substantially lower concentrations of outer block incorporation compared to traditional triblock copolymers to achieve similar mechanical properties and microphase separated morphologies. / Ph. D.
372

The effects of different thermal environmental conditions on the performance of automatic and controlled processes

Hughes, Raymond E. 03 March 2009 (has links)
This research investigated the effect of four thermal environmental conditions on the performance of automatic and controlled processes. The environmental conditions included temperature and relative humidity combinations of (1) 25°C with 60% r.h., (2) 33°C with 38% r.h., (3) 33°C with 66% r.h., and (4) 33°C with 92% r.h . These combinations corresponded to vapor pressures of 15 mm Hg, 15 mm Hg, 25 mm Hg, and 35 mm Hg respectively. To analyze the data from both the automatic and the controlled processing task, data were transformed to an equivalent scale using proportion scores. F-values well below 1 indicated that variability dominated the experiment. Type of processing was the only significant factor in the experiment. Upon analyzing each task separately, it was discovered that the major source of variability was the controlled processing task. The automatic processing task had no significant main effects or interactions. The three levels of vapor pressure were almost found to be significantly different (Pr> F=O.07). All analyses of the controlled processing task were dominated by variability. A larger sample size would be needed to find statistically significant differences in observed means and standard deviations. Power analyses indicate hundreds, and in some cases even thousands, more subjects would need to be run for the controlled processing task or proportion score analyses. Although fewer subjects are needed for the automatic processing task, the power of the experiment was very low. Future researchers are advised to improve or replace the controlled processing task and to use more subjects. In addition, the variability of the experiment should be reduced by (1) choosing a more homogeneous group of subjects, (2) providing an incentive to the subjects to provide a constant level of effort, and (3) using more extreme environmental conditions. / Master of Science
373

Design and Fabrication of the Emitter Controlled Thyristor

Liu, Yin 21 June 2001 (has links)
The Emitter Controlled Thyristor (ECT) is a new MOS-Gated Thyristor (MGT) that combines the ease of a MOS gate control with the superior current carrying capability of a thyristor structure for high-power applications. An ECT is composed of an emitter switch in series with the thyristor, an emitter-short switch in parallel with the emitter junction of the thyristor, a turn-on FET and the main thyristor structure. Numerical analysis shows that the ECT also offers superior high voltage current saturation capability even for high breakdown voltage ratings. Two different ECT structures are investigated in this research from numerical simulations to experimental fabrications. A novel ECT structure that utilizes IGBT compatible fabrication process was proposed. The emitter short FET, emitter switch FET and turn-on FET are all integrated with a high voltage thyristor. Numerical simulation results show that the ECT has a better conductivity modulation than that of the IGBT and at the same time exhibits superior high voltage current saturation capability, superior FBSOA and RBSOA. The technology trade-off between turn-off energy loss and forward voltage drop of the ECT is also better than that of the IGBT because of the stronger conductivity modulation. A novel self-aligned process is developed to fabricate the device. Experimental characteristics of the fabricated ECT devices show that the ECT achieves lower forward voltage drop and superior high voltage current saturation capability. A Hybrid ECT (HECT) structure was also developed in this research work. The HECT uses an external FET to realize the emitter switching function, hence a complicated fabrication issue was separated into two simple one. The cost of the fabrication decreases and the yield increases due to the hybrid integration. Numerical simulations demonstrate the superior on-state voltage drop and high voltage current saturation capability. A novel seven-mask process was developed to fabricate the HECT. Experimental results show that the HECT could achieve the lower forward voltage drop and superior current saturation capability. The resistive switching test was carried out to demonstrate the switching characteristics of the HECT. / Master of Science
374

Effectiveness of educational interventions in improving detection and management of dementia in primary care: cluster randomised controlled study

Downs, Murna G., Bryans, M., Turner, S., Wilcock, J., Keady, J., Levin, E., O'Carroll, R., Howie, K., Lliffe, S. January 2006 (has links)
No
375

Psychosocial interventions for people with dementia: An overview and commentary on recent developments

Oyebode, Jan, Parveen, Sahdia 24 May 2016 (has links)
Yes / An influential review in 2010 concluded that non-pharmacological multi-component interventions have positive effects on cognitive functioning, activities of daily living, behaviour and mood of people with dementia. Our aim here is to provide an up-to-date overview of research into psychosocial interventions and their impact on psychosocial outcomes. We focused on randomised controlled trials, controlled studies and reviews published between October 2008 and August 2015, since the earlier review. The search of PsychInfo, Medline and the Cochrane database of systematic reviews yielded 61 relevant articles, organised into four themes echoing key phases of the care pathway: Living at home with dementia (five reviews, eight studies), carer interventions (three reviews, four studies), interventions in residential care (16 reviews, 12 studies) and end-of-life care (three reviews, two studies), along with an additional group spanning community and institutional settings (six reviews, two studies). Community findings suggested that appointment of dementia specialists and attention to case management can produce positive outcomes; physical therapies, cognitive training and modified cognitive behaviour therapy also had a range of benefits. There was more limited evidence of positive benefits for people with dementia through interventions with family carers. Thirty-two articles focused on the management of ‘behavioural symptoms’ through a range of interventions all of which had some evidence of benefit. Also a range of multi-component and specific interventions had benefits for cognitive, emotional and behavioural well-being of people with dementia in residential settings, as well as for quality of life. Overall, interventions tended to be short term with impact only measured in the short term. We recommend further research on interventions to promote living well in the community post-diagnosis and to address end-of-life care. Development of psychosocial interventions would benefit from moving beyond the focus on control of behaviours to focus on wider aspects of life for people with dementia.
376

Attentional bias retraining in cigarette smokers attempting smoking cessation (ARTS): study protocol for a double blind randomised controlled trial

Begh, R., Munafò, M.R., Shiffman, S., Ferguson, S.G., Nichols, L., Mohammed, Mohammed A., Holder, R.L., Sutton, S., Aveyard, P. January 2013 (has links)
Yes / Smokers attend preferentially to cigarettes and other smoking-related cues in the environment, in what is known as an attentional bias. There is evidence that attentional bias may contribute to craving and failure to stop smoking. Attentional retraining procedures have been used in laboratory studies to train smokers to reduce attentional bias, although these procedures have not been applied in smoking cessation programmes. This trial will examine the efficacy of multiple sessions of attentional retraining on attentional bias, craving, and abstinence in smokers attempting cessation. This is a double-blind randomised controlled trial. Adult smokers attending a 7-session weekly stop smoking clinic will be randomised to either a modified visual probe task with attentional retraining or placebo training. Training will start 1 week prior to quit day and be given weekly for 5 sessions. Both groups will receive 21 mg transdermal nicotine patches for 8–12 weeks and withdrawal-orientated behavioural support for 7 sessions. Primary outcome measures are the change in attentional bias reaction time and urge to smoke on the Mood and Physical Symptoms Scale at 4 weeks post-quit. Secondary outcome measures include differences in withdrawal, time to first lapse and prolonged abstinence at 4 weeks post-quit, which will be biochemically validated at each clinic visit. Follow-up will take place at 8 weeks, 3 months and 6 months post-quit. This is the first randomised controlled trial of attentional retraining in smokers attempting cessation. This trial could provide proof of principle for a treatment aimed at a fundamental cause of addiction. / National Institute for Health Research (NIHR) Doctoral Research Fellowship (DRF) awarded to RB (DRF-2009-02-15)
377

Putting Life in Years (PLINY): a randomised controlled trial and mixed-methods process evaluation of a telephone friendship intervention to improve mental well-being in independently living older people

Hind, D., Mountain, Gail, Gossage-Worrall, R., Walters, S.J., Duncan, R., Newbould, L., Rex, S., Jones, C., Bowling, A., Cattan, M., Cairns, A., Cooper, C., Goyder, E.C., Tudor Edwards, R. 12 1900 (has links)
Yes / Social isolation in older adults is associated with morbidity. Evaluating interventions to promote social engagement is a research priority. Methods: A parallel-group randomised controlled trial was planned to evaluate whether telephone friendship (TF) improves the well-being of independently living older people. An internal pilot aimed to recruit 68 participants by 30 September 2012, with 80% retained at 6 months. Randomisation was web based and only analysts were blind to allocation. A service provider was contracted to train 10 volunteer facilitators by 1 April 2012 and 10 more by 1 September 2012. Participants were aged > 74 years with good cognitive function and living independently in an urban community. The intervention arm of the trial consisted of manualised TF with standardised training: (1) one-to-one befriending (10- to 20-minute calls once per week for up to 6 weeks made by volunteer facilitators) followed by (2) TF groups of six participants (1-hour teleconferences once per week for 12 weeks facilitated by the same volunteer). Friendship groups aimed to enhance social support and increase opportunities for social interaction to maintain well-being. This was compared with usual health and social care provision. The primary clinical outcome was the Short Form questionnaire-36 items (SF-36) mental health dimension score at 6 months post randomisation. Qualitative research assessing intervention acceptability (participants) and implementation issues (facilitators) and an intervention fidelity assessment were also carried out. Intervention implementation was documented through e-mails, meeting minutes and field notes. Acceptability was assessed through framework analysis of semistructured interviews. Two researchers coded audio recordings of telephone discussions for fidelity using a specially designed checklist. Results: In total, 157 people were randomised to the TF group (n = 78) or the control group (n = 79). Pilot recruitment and retention targets were met. Ten volunteers were trained by 1 September 2012; after volunteer attrition, three out of the 10 volunteers delivered the group intervention. In total, 50 out of the 78 TF participants did not receive the intervention and the trial was closed early. A total of 56 people contributed primary outcome data from the TF (n = 26) and control (n = 30) arms. The mean difference in SF-36 mental health score was 9.5 (95% confidence interval 4.5 to 14.5) after adjusting for age, sex and baseline score. Participants who were interviewed (n = 19) generally declared that the intervention was acceptable. Participant dissatisfaction with closure of the groups was reported (n = 4). Dissatisfaction focused on lack of face-to-face contact and shared interests or attitudes. Larger groups experienced better cohesion. Interviewed volunteers (n = 3) expressed a lack of clarity about procedures, anxieties about managing group dynamics and a lack of confidence in the training and in their management and found scheduling calls challenging. Training was 91–95% adherent with the checklist (39 items; three groups). Intervention fidelity ranged from 30.2% to 52.1% (28–41 items; three groups, three time points), indicating that groups were not facilitated in line with training, namely with regard to the setting of ground rules, the maintenance of confidentiality and facilitating contact between participants. Conclusions: Although the trial was unsuccessful for a range of logistical reasons, the experience gained is of value for the design and conduct of future trials. Participant recruitment and retention were feasible. Small voluntary sector organisations may be unable to recruit, train and retain adequate numbers of volunteers to implement new services at scale over a short time scale. Such risks might be mitigated by multicentre trials using multiple providers and specialists to recruit and manage volunteers. / Funding for this study was provided by the Public Health Research programme of the National Institute for Health Research.
378

Core outcome measures for interventions to prevent or slow the progress of dementia for people living with mild to moderate dementia: Systematic review and consensus recommendations

Chatters, R., Newbould, L., Sprange, K., Hind, D., Mountain, Gail, Shortland, K., Powell, L., Gossage-Worrall, R., Chater, T., Keetharuth, A., Lee, E., Woods, B. 20 February 2018 (has links)
Yes / Recruiting isolated older adults to clinical trials is complex, time-consuming and difficult. Previous studies have suggested querying existing databases to identify appropriate potential participants. We aim to compare recruitment techniques (general practitioner (GP) mail-outs, community engagement and clinician referrals) used in three randomised controlled trial (RCT) studies assessing the feasibility or effectiveness of two preventative interventions in isolated older adults (the Lifestyle Matters and Putting Life In Years interventions). Methods: During the three studies (the Lifestyle Matters feasibility study, the Lifestyle Matters RCT, the Putting Life In Years RCT) data were collected about how participants were recruited. The number of letters sent by GP surgeries for each study was recorded. In the Lifestyle Matters RCT, we qualitatively interviewed participants and intervention facilitators at 6 months post randomisation to seek their thoughts on the recruitment process. Results: Referrals were planned to be the main source of recruitment in the Lifestyle Matters feasibility study, but due to a lack of engagement from district nurses, community engagement was the main source of recruitment. District nurse referrals and community engagement were also utilised in the Lifestyle Matters and Putting Life In Years RCTs; both mechanisms yielded few participants. GP mail-outs were the main source of recruitment in both the RCTs, but of those contacted, recruiting yield was low (< 3%). Facilitators of the Lifestyle Matters intervention questioned whether the most appropriate individuals had been recruited. Participants recommended that direct contact with health professionals would be the most beneficial way to recruit. Conclusions: Recruitment to the Lifestyle Matters RCT did not mirror recruitment to the feasibility study of the same intervention. Direct district nurse referrals were not effective at recruiting participants. The majority of participants were recruited via GP mail-outs, which may have led to isolated individuals not being recruited to the trials. Further research is required into alternative recruitment techniques, including respondent-driven sampling plus mechanisms which will promote health care professionals to recruit vulnerable populations to research. / Medical Research Council (grant number G1001406); Sheffield Health and Social Research Consortium; National Institute for Health Research Public Health Research programme (project number 09/ 3004/01)
379

Recruitment of older adults to three preventative lifestyle improvement studies

Chatters, R., Newbould, L., Sprange, K., Hind, D., Mountain, Gail, Shortland, K., Powell, L., Gossage-Worrall, R., Chater, T., Keetharuth, A., Lee, E., Woods, B. 20 February 2018 (has links)
Yes / Recruiting isolated older adults to clinical trials is complex, time-consuming and difficult. Previous studies have suggested querying existing databases to identify appropriate potential participants. We aim to compare recruitment techniques (general practitioner (GP) mail-outs, community engagement and clinician referrals) used in three randomised controlled trial (RCT) studies assessing the feasibility or effectiveness of two preventative interventions in isolated older adults (the Lifestyle Matters and Putting Life In Years interventions). Methods: During the three studies (the Lifestyle Matters feasibility study, the Lifestyle Matters RCT, the Putting Life In Years RCT) data were collected about how participants were recruited. The number of letters sent by GP surgeries for each study was recorded. In the Lifestyle Matters RCT, we qualitatively interviewed participants and intervention facilitators at 6 months post randomisation to seek their thoughts on the recruitment process. Results: Referrals were planned to be the main source of recruitment in the Lifestyle Matters feasibility study, but due to a lack of engagement from district nurses, community engagement was the main source of recruitment. District nurse referrals and community engagement were also utilised in the Lifestyle Matters and Putting Life In Years RCTs; both mechanisms yielded few participants. GP mail-outs were the main source of recruitment in both the RCTs, but of those contacted, recruiting yield was low (< 3%). Facilitators of the Lifestyle Matters intervention questioned whether the most appropriate individuals had been recruited. Participants recommended that direct contact with health professionals would be the most beneficial way to recruit. Conclusions: Recruitment to the Lifestyle Matters RCT did not mirror recruitment to the feasibility study of the same intervention. Direct district nurse referrals were not effective at recruiting participants. The majority of participants were recruited via GP mail-outs, which may have led to isolated individuals not being recruited to the trials. Further research is required into alternative recruitment techniques, including respondent-driven sampling plus mechanisms which will promote health care professionals to recruit vulnerable populations to research. / The Lifestyle Matters RCT was funded by the Medical Research Council (grant number G1001406); Sheffield Health and Social Research Consortium; National Institute for Health Research Public Health Research programme (project number 09/ 3004/01)
380

The Terrorizing Totality of the Bureaucratic Society of Controlled Consummption

Kirsch, Robert Emmanuel 05 June 2008 (has links)
As an advanced society of industrialized capitalism has an ever-tighter grip on our everyday lives, I ask if rebellion is possible in the current context. To this end, I formulate a model of rebellion based on my readings of Marcuse and Camus; from Marcuse, the idea that a person can formulate a rebellious subjectivity through the consumption of art in the creation of the aesthetic dimension, and from Camus, an individual placing limits on what oppression he will take from an existing order and at what point she will say "no" to that order and giving a concurrent "yes" by acting in such a way that fosters Camus' human community. I argue after the Cold War especially, the bureaucratic society of controlled consumption closes down spaces for meaningful rebellion. As we have moved from hip consumerism to market populism, the goal of the existing order is for the citizens thereof to legitimate the order. I analyze various groups to see if they are engaging in rebellion, such as Al Qaeda, Hamas, the Earth and Animal Liberation Fronts, and analyze their methods. I find that instead of labeling as terrorist or rebel, we should let the rebellious subjectivity guide our judgment of their actions. Ultimately, I conclude that rebellion is still a possibility even in the encroaching totality of the bureaucratic society of controlled consumption, and that a preservation of the rebellious subjectivity can provide a basis for formulating a rebellious praxis not yet called into being. / Master of Arts

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