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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.
71

pH Responsive Highly Branched Poly(N-isopropylacrylamide) with Trihistidine or Acid Chain Ends

Swift, Thomas, Lapworth, J., Swindells, K., Swanson, L., Rimmer, Stephen 19 July 2016 (has links)
Yes / Thermally responsive highly branched poly(N-isopropyl acrylamide)s (HB-PNIPAM) were prepared and end-functionalised to give polymers with acid or trihistidine end groups. These polymers exhibit a broad coil-to-globule transition across a wide temperature range which can be measured using covalently attached fluorescent tags. The acid chain ends provided a material with a distinct change in solution behaviour at pH close to the pKa of the carboxylate group. At pH 11 this polymer did not show a cloud point up to 50 °C but fluorescence measurements on the labelled polymers showed that a coil to glubule transition did take place. The globular state, above the LCST, appeared to be more swollen if the end group carried charge then when it was uncharged. A polymer with trihistidine and free carboxylate chain ends, which contained multiple charges at various pH, did show LCSTs at all pH and the polymer globule was shown to be swollen at each pH.
72

Thermally switchable polymers achieve controlled Escherichia coli detachment

Hook, A.L., Chang, Chien-Yi, Scurr, D.J., Langer, R., Anderson, D.G., Williams, P., Davies, M.C., Alexander, M.R. 04 February 2014 (has links)
Yes / The thermally triggered release of up to 96% of attached uropathogenic E. coli is achieved on two polymers with opposite changes in surface wettability upon reduction in temperature. This demonstrates that the bacterial attachment to a surface cannot be explained in terms of water contact angle alone; rather, the surface composition of the polymer plays the key role. / Wellcome Trust (grant number 085245) and the NIH (grant number R01 DE016516)
73

The influence of free-living activity and inactivity on health outcomes and responsiveness to exercise training

Keadle, Sarah Kozey 01 May 2012 (has links)
On average, starting an exercise training program decreases one’s risk for chronic disease. However, there is remarkable individual variability in physiologic responses to exercise training. The activity and inactivity during the remaining 95% of the day (when the individual is not training) is rarely considered. The overall objective of this dissertation was to apply validated sedentary behavior (SB) and physical activity (PA) measurement techniques during an exercise training study to determine if time spent in SB and PA outside of training influences the physiological response to training. Twenty subjects participated in a pilot study to determine the feasibility of reducing SB and the validity of PA monitors for measuring SB compared to direct observation (DO). Participants completed a 1-week baseline period and a 1-week intervention period, where they were instructed to decrease SB. The correlation between the AP and DO was R2=0.94 and the AG100 and DO sedentary minutes was R2=0.39. SB significantly decreased from 67% of wear time (baseline period) to 62.7% of wear time (intervention period) according to AP. Only the AP was able to detect reductions in SB and was more precise than the AG. Study Two was a 12-week randomized controlled study. There were 4-groups that were instructed to: 1) CON: maintain habitual PA and SB 2) rST: reduce and break-up SB and increase daily steps 3) EX: exercise 5-days per week for 40-minutes per session at moderate intensity 4) EX-rST: combination of EX and rST. Cardiovascular disease risk factors were assessed pre-and post-intervention. The AP was used to verify AP between-group differences in activity at four time-points. EX-rST had improvements in insulin action variables that EX did not. All other physiologic responses to training were similar between EX groups and rST has less robust changes than either EX group. These data provide validation of activity monitors for measuring SB and present preliminary evidence that activity outside of exercise training may influence the metabolic response to training. This dissertation shows that what is done outside of exercise training can and should be quantified using objective monitors that assess daily exposure to activity and inactivity behavior.
74

The Relationship between Reciprocal Social Impairments and Psychopathology in Children with Intellectual Disability

Kaat, Aaron J. 27 September 2011 (has links)
No description available.
75

Prospective Role of Reward Responsiveness in Depression and Posttraumatic Stress Disorder Symptom Trajectories following Traumatic Exposure

Forbes, Courtney N. 15 September 2022 (has links)
No description available.
76

Investigating aspects of diversity, equity, and inclusion, adaptive management, and evaluation in environmental education

Anderson, Kelley Christine 24 May 2021 (has links)
This dissertation investigates aspects of diversity, equity, and inclusion, adaptive management, and evaluation in environmental education (EE), and is composed of and introduction, three stand-alone manuscripts (Chapters 2-4), and a conclusion. The introduction gives a brief overview of EE and explains why the topics of study included in this dissertation are important to address. In Chapter 2, we used pre-experience student surveys to understand how preparation, adult support, and students' racial identities influence student attendance to a residential environmental education program. Chapter 3 identifies areas and approaches for improving evaluation processes in EE and practitioner satisfaction with those processes. We collected these data using an online survey promoted on social media and emailed to EE practitioners involved in the North American Association for Environmental Education and the Association of Nature Center Administrators. Chapter 4 outlines a culturally responsive evaluation framework for use in EE. The results of these studies show there is far more to be done in the field of EE to create a welcoming and inclusive space for all audiences, to promote the use of evaluation as a tool for continuous learning and improvement, and to ensure evaluations are valid for and reflective of the culture of program participants. The conclusion discusses the two prevalent themes embedded in these manuscripts, namely diversity, equity and inclusion, and evaluation in EE, and ends with a reflection on my time here as a Ph.D. student and where I see my career path heading. This dissertation is meant to provide ideas and suggestions to environmental education practitioners that they can implement in hopes of improving EE and evaluation to meet the needs of all audiences and to address global environmental challenges. / Doctor of Philosophy / To work collaboratively and find solutions to the sustainability challenges and social justice issues we face as a society requires new generations to obtain a wide range of knowledge, skills, and motivations. Environmental education (EE) has been shown to equip students with these necessary skills, including increasing knowledge and awareness about environmental issues, enhancing or changing attitudes as they relate to the environment, promoting environmentally responsible behaviors, and building critical thinking, leadership, and collaboration skills. There is a growing recognition that the field of EE must continually adjust and improve its programming to meet the needs of all audiences and to remain relevant for our ever-changing world. The foundations of EE stem from White, Eurocentric values and world views, which can perpetuate inequities in program attendance, participation, and impact between Black, Indigenous, and People of Color (BIPOC) and White people. The research included in this dissertation investigates aspects of diversity, equity, and inclusion, adaptive management, and evaluation in EE. Results show there is far more to be done in the field of EE to create a welcoming and inclusive space for all audiences, to promote the use of evaluation as a tool for continuous learning and improvement, and to ensure evaluations are valid for and reflective of the culture of program participants. The conclusion of this dissertation discusses two prevalent themes embedded in these manuscripts, namely diversity, equity and inclusion, and evaluation in EE, and ends with a reflection on my time here as a Ph.D. student and where I see my career path heading. This dissertation is meant to provide ideas and suggestions to environmental education practitioners that they can implement in hopes of improving EE and evaluation to meet the needs of all audiences and to address global environmental and social challenges.
77

Structure/Function Analysis of the Quorum-sensing Regulator EsaR from the Plant Pathogen Pantoea stewartii

Schu, Daniel Joseph 24 July 2009 (has links)
Pantoea stewartii subsp. stewarti is the causative agent of Stewart's wilt disease in maize. Disease symptoms develop after the bacteria grow to high cell densities in the plant xylem and secrete an abundance of exopolysaccharide (EPS). EPS production is regulated by quorum sensing. Two regulatory proteins are key to the process of quorum sensing, the LuxI and LuxR homologues EsaI and EsaR. Most LuxR homologues function as activators of transcription in the presence of their cognate acylated homoserine lactone signal (AHL). EsaR utilizes an AHL-response opposite of the majority of the LuxR homologues. EsaR represses EPS production at low cell densities. However, at high cell densities when high concentrations of AHL are present, EsaR is inactivated and derepression of EPS production occurs. The mechanism that enables EsaR to respond to AHL in a manner opposite to that of most LuxR homologues remains elusive. A comparative study of EsaR and the well characterized quorum-sensing regulators LuxR from Vibrio fischeri and TraR from Agrobacterium tumefaciens was initiated. Previous studies demonstrated that in the absence of AHL, EsaR retains the ability to function as a weak activator of the lux operon in recombinant Escherichia coli. This thesis research further characterized the role of EsaR as an activator. Variant forms of EsaR with deletions or single residue substitutions were generated and their ability to regulate transcription was examined in vivo. Furthermore, a native EsaR-activated promoter has been identified, which controls expression of a putative regulatory sRNA in P. stewartii. It is apparent that EsaR functions as a transcription factor at low concentrations of AHL as demonstrated by its ability to inhibit EPS production. At high concentrations, the AHL appears to bind and cause a conformational shift in the protein leading to its inactivation. The second goal of this study was to further elucidate the mechanism by which AHL regulates EsaR. Pulse-chase experiments demonstrated that EsaR is resistant to proteases with or without AHL in vivo. Limited proteolytic digestions in vitro suggest that the protein does undergo conformational changes in response to AHL. Gel filtration chromatography, sucrose gradient ultracentrifugation, and cross-linking experiments proved that this conformational change does not impact the multimeric state of EsaR. To better understand the mechanism of regulation by AHL, the final goal of this project was to examine the interactions which result in EsaR-responsiveness to AHL. Several individual amino acid substitutions were identified that cause EsaR to function in an AHL-independent manner, by which variants retain the ability to bind and block gene expression in the presence of AHL. These residues have been mapped onto a homology model of EsaR and their role has been examined in vitro. The ability of these EsaR* variants to bind AHL and an analysis of the effects individual mutations have on the overall conformation of the protein was performed. Overall this study has revealed several unique aspects of the quorum-sensing system in P. stewartii whereby gene expression is regulated at both low and high cell density. Studies were also initiated to examine the mechanism of AHL-responsiveness of EsaR. The mechanism by which AHL modulates most LuxR homologues remains elusive. The ability to purify EsaR +/- its cognate AHL may prove critical in elucidating this mechanism. / Ph. D.
78

The association between maternal responsiveness and child social and emotional development

Best, Lara January 2013 (has links)
Introduction. A mother’s verbal and non-verbal behaviour towards her infant is known as maternal responsiveness (MR). Positive MR is associated with better child social and emotional development (SED). A mother’s ability to accurately recognise emotions is thought to enhance MR. Method. Data from 1,122 mother-infant interactions from a longitudinal birth cohort study, was used firstly to examine whether positive MR at 12 months was associated with better child and adolescent SED, and secondly to explore whether better maternal facial and vocal expression recognition at 151 months was associated with positive MR and child SED. MR was measured using the Thorpe Interaction Measure (TIM) from observed mother-infant interactions and SED from questionnaire data adjusting for potential confounding variables. A test of facial expression recognition was used with vocal expression recognition additionally used in mothers. Results. Logistic regression revealed that positive MR was associated with positive SED outcomes in childhood but there was little effect in adolescence. Positive MR was associated with mothers having better facial and vocal expression recognition at 151 months and these recognition skills were associated with children showing less emotional problems at 158 months independent of MR. Adjustments for confounding variables had no effect on these results. Conclusion: These findings support the benefit of positive MR on a child’s SED in middle childhood. Further, the findings suggest that a mother’s facial and vocal expression recognition skills are important to both MR and a child’s SED. Limitations include subjective reporting of SED.
79

The impact of experiential avoidance on reduced positive emotional responsivity in post traumatic stress disorder

Copestake, Claudia Catarina January 2014 (has links)
Experiential avoidance (EA), or the evasion of unpleasant internal experiences, is key to changes in emotional responsivity in Posttraumatic Stress Disorder (PTSD). EA has been linked to altered negative emotional reactivity in PTSD, but it remains unclear whether EA is linked to altered positive reactivity in PTSD, i.e. anhedonia. Therefore the study examined how manipulating EA influences emotional responsiveness in a non-clinical adult population (N=74). Positive emotion reactivity (self-report and psychophysiology) was measured before and after viewing a laboratory analogue trauma induction, with half of participants instructed to adopt the detached protector (DP) mode as an example of EA during trauma viewing and half of participants in an uninstructed control condition. Following the DP mode instructions reduced negative emotion experience during the trauma induction, relative to the control condition. However counter to prediction, there was no carry over onto blunted positive emotion experience or psychophysiological response in the experimental condition (relative to the control condition) when recalling positive memories and imagining positive future events. No significant relationships were identified between trait EA levels and anhedonia symptoms or pre-manipulation positive emotional responsiveness in the laboratory. Overall, the current findings offer no support for the hypothesis that EA contributes to anhedonia.
80

Capacity dimensioning of operations capacity in manufacturing companies

Sollander, Kristina, Hedvall, Lisa January 2016 (has links)
Purpose:To investigate how managers work with capacity dimensioning and what the main challenges are in order to balance efficiency and responsiveness in the continuous operations, as well as investigate what patterns and trends that can be identified within the capacity dimensioning approach. Methodology:A multiple case study was conducted including 14 manufacturing companies. Empirical data was collected through semi-structured interviews and used to explain the phenomenon of capacity dimensioning. Differences and similarities in the way companies approach capacity dimensioning was investigated though a cross-case analysis. The research is of exploratory and inductive character. Findings:A general process for capacity dimensioning has been established and affecting aspects and challenges has been identified. Potential trends and relationships have been investigated for the capacity dimensioning approach, with a potential connection between flexibility and investment strategy with introduction period in human resources. Further the capacity strategies tend to vary depending on alternative capacity sources. Theoretical implications:Information is provided for how capacity dimensioning is done at companies today, connections are strong to adjacent theories as S&OP but with more detail in the area of setting the capacity level. Managerial implications:The capacity dimensioning does not have a solution that suits all companies, but communication and alignment in the supply chain should not be underestimated for successful capacity dimensioning. Research delimitations:The research is conducted on manufacturing companies active in Sweden, other countries or continents of the world could generate other results because of different culture and laws. Further, service companies could also have provided other results.

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