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Yes / The behavior of a linear copolymer of N-isopropyl acrylamide with pendant vancomycin functionality was compared to an analogous highly branched copolymer with vancomycin functionality at the chain ends. Highly branched poly(N-isopropylacrylamide) modified with vancomycin (HB-PNIPAM-van) was synthesized by functionalization of the HB-PNIPAM, prepared using reversible addition-fragmentation chain transfer polymerization. Linear PNIPAM with pendant vancomycin functionality (L-PNIPAM-van) was synthesized by functionalization of poly(N-isopropyl acrylamide-co-vinyl benzoic acid). HB-PNIPAM-van aggregated S. aureus effectively whereas the L-PNIPAM-van polymer did not. It was found that when the HB-PNIPAM-van was incubated with S. aureus the resultant phase transition provided an increase in the intensity of fluorescence of a solvatochromic dye, nile red, added to the system. In contrast, a significantly lower increase in fluorescence intensity was obtained when L-PNIPAM-van was incubated with S. aureus. These data showed that the degree of desolvation of HB-PNIPAM-van was much greater than the desolvation of the linear version. Using microCalorimetry it was shown that there were no significant differences in the affinities of the polymer ligands for D-Ala-D-Ala and therefore differences in the interactions with bacteria were associated with changes in the probability of access of the polymer bound ligands to the D-Ala-D-Ala dipeptide. The data support the hypothesis that generation of polymer systems that respond to cellular targets, for applications such as cell targeting, detection of pathogens etc., requires the use of branched polymers with ligands situated at the chain ends. / MRC

<p dir="ltr">The implementation of vibrotactile stimuli has grown in necessity where visual and auditory modalities are overloaded. However, how attention is oriented using vibrotactile information has been minimally investigated compared to other modalities, such as visual and auditory stimuli. The ability to elicit an appropriate mapping between a response from a specific vibrotactile stimulus can be explained in three different frames of reference accounts: internal, external, or remapping. Previous research has answered questions relating to the ability to use different reference frames but have yet to agree which frame orients attention for creating an automatic response. Using various stimulus-response mapping effects, the current study investigated how competing frames of reference are used to orient attention to select a response based on specific characteristics of vibrotactile stimuli. Experiment 1 validated the novel apparatus developed for this study by obtaining a stimulus-response compatibility effect. Experiment 2 investigated if an external or internal reference frame is used to orient attention automatically. The uncrossed-hands condition provided a replication of Experiment 1 and confirmed that a stimulus-response compatibility effect was present. For the crossed-hands condition, a diminished, reverse stimulus-response compatibility effect was present. Experiment 3 found no meaningful difference between a magnitude aligned (i.e., left associated with low frequency) versus misaligned (i.e., left associated with high frequency) conditions for frequency of vibrotactile stimuli, suggesting vibrotactile stimuli do not hold a mental magnitude line. Overall, the results from Experiments 1 and 2 provide evidence that processing of vibrotactile information is not reliant on only an internal reference frame but instead the external frame has some influence on selecting a motor response. Experiment 3 also suggests that task context influenced the stimulus and response mapping provided in the instructions, rather than the intrinsic, anatomical representation of vibrotactile stimuli.</p>

The present study determined how object-based alignment effects are influenced by the arrangement of the stimuli and response options. It is well established that the magnitude of these effects differ depending on the mode of responding. This finding has often been used to support claims that viewing photograph images of graspable objects can automatically trigger motor representations, regardless of the intentions of the observer. Our findings instead suggest that the distinction between response modes is primarily a difference in response discriminability. More importantly, it was found that this influence of response discriminability works in a completely opposite manner, dependent on the technique used to center the frying pan stimuli. Pixel-centered stimuli produced a handle-based alignment effect that was enhanced under conditions of high response discriminability. Object-centered stimuli produced a body-based alignment effect that was diminished under conditions of high-response discriminability. These findings provide overwhelming evidence that qualitatively different principles govern the alignment effect found with pixel-centered and object-centered stimuli. Crucially, these finding also provide strong evidence against the notion that motor representations are triggered by images of graspable objects in the absence of an intention to act. / Graduate

Polymeric materials with inherent stimulus response represent an ever-growing area of research. In particular, block copolymers demonstrate exciting properties owing to their enhanced mechanical strength and microphase separation. Incorporating functionality into block copolymers proves useful in enhancing their utility. Presently, synthesis and subsequent post-polymerization modification achieved this for a range of block copolymers. In particular, neutralization of acid-containing polymers readily imparted ionic functionality and yielded microphase-separated block copolymer domains, enhancing polymer thermomechanical properties and ion transport. An ABA triblock copolymer composed of mechanically reinforcing polystyrene outer blocks and ionic central poly(1-methylimidazolium acrylate) block acted as a host for ionic liquid that caused an evolution in bulk morphology, resulting in enhanced ionic conductivity. The resulting membrane also exhibited a strong electromechanical actuation response under applied potential. Adding ionic liquid doped with a corresponding lithium salt enabled evaluation of sulfonated block copolymers as components of ternary polymer electrolytes, relevant for battery applications. Modification of a sulfonic acid-containing pentablock copolymer presented photocurable functional groups to the ionic domains which enabled their UV irradiation-induced curing. This novel route of modifying ion-containing block copolymers resulted in enhanced thermomechanical properties and enabled healing of physical defects in the film, unprecedented for ion-containing block copolymers. Covalent networks represent a relevant area of research for a wide variety of applications such as coatings, adhesives, and scaffolds. Careful design of degradable crosslinkers enables stimulus response in these networks by eliminating covalent crosslinks and affording a soluble product. Extension of poly(ethylene glycol) methacrylate-based network formation into three dimensions using microstereolithography resulted in novel acid-degradable 3D-printed parts. An additional study investigated mixtures of acrylamide-modified poly(vinyl alcohol) and poly(ethylene glycol) diacrylate as water-soluble resins for the direct formation of hydrogels from solution. Photorheology and photocalorimetry investigated the thermal and mechanical changes inherent in the curing process and evaluated the mixtures as a platform for microstereolithography. / Ph. D.

This thesis concerns selective attention in the context of the Stroop task (identify the colour) and Reverse Stroop task (identify the word). When a person is asked to select and identify one dimension of a bidimensional stimulus (e. g. , the word RED printed in green) the typical finding is that the word influences colour identification (i. e. , the Stroop effect) but the colour does not influence word identification (i. e. , no Reverse Stroop effect). A major account of performance in these tasks posits that one dimension interferes with the other only when a translation occurs (e. g. , Roelofs, <i>Psychological Review, 2003</i>; Sugg & McDonald, <i>Journal of Experimental Psychology: Human Perception & Performance, 1994</i>; Virzi & Egeth, <i>Memory & Cognition, 1985</i>). This translation assumption is implicit in virtually all work in the field. The first part of this thesis completely undermines the translation assumption. In a series of four experiments (two unique paradigms), I demonstrate that interference from the colour in a Reverse Stroop task occurs in the absence of a translation. The second part of this thesis contains two additional experiments designed to discriminate between translation effects and response conflict effects. The results of these experiments confirm that a translation was not required because no stimulus conflict effect, the most likely locus of a translation effect, was observed. However, response conflict effects were observed. The third part of this thesis implements a computational model based on the principle that the strength of association (Cohen, Dunbar, & McClelland, <i>Psychological Review, 1990</i>) between a specific stimulus and its response (Logan, </i>Psychological Review, 1988</i>) is important in determining the influence of the irrelevant dimension. This model has no translation mechanism. A final experiment was conducted to test this model; the model accounted for over 98% of the variance in RTs and 92% of the variance in interference and facilitation scores in both the Stroop and Reverse Stroop tasks independent of whether a translation was required.

The present study examined the effect of first-list stimulus context (color versus no color) and two degrees of first-list learning (twenty trials versus five trials) on cue selection and transfer of training. College students learned two paired-associate lists consisting of highly similar trigrams as the stimulus terms and nouns as the response terms. The second list consisted of twelve items presented on homogeneous white backgrounds for eighteen trials. Four secondlist items represented each of three transfer paradigms--A -B,A-B; A-B,A-C; and A-BC-D. It was concluded that color context draws attention to the color-backed items during the early stages of learning but is not selected for encoding until the later stages of learning.

Objective: Anxiety and depression have been conceptualised as being associated with “an abundance of habit and a dearth of control” (Hertel, 2015, p. 1). There has been a recent and burgeoning interest toward understanding the role of habits in health psychology and in the psychological disorders of obsessive-compulsive disorder and addiction in particular. To the author’s knowledge, there has been no previous systematic review that aimed to summarise the research investigating the involvement of mental habits in anxiety and depression in clinical and non-clinical populations. Method: The term habit was operationalized and inclusion criteria were specified in the domains of habit measurement, research paradigms, and manipulation tasks. A search across four databases was conducted: Web of Science, EBSCOhost, PubMed and OVID (PsycARTICLES and Journals@OVID). A progressive screening procedure yielded 8 relevant studies related to mental habits in anxiety (n = 1), depression (n = 4) and both anxiety and depression (n = 3). Results: Self-report habit measures correlate with the presence of symptoms. Computational modelling reinforcement learning and goal-devaluation paradigms demonstrate that anxiety and depression are associated with deficits in goal-directed learning and decision-making in favour of habitual learning strategies. Cognitive bias modification meets the criteria for enabling habit change and can strengthen or weaken interpretative habits in response to training. Conclusions: Despite considerable variability and limitations in the design of the studies appraised in this review, overall findings indicate support for habitual thought processes being implicated in anxiety and depression. Treating problematic thought processes in anxiety and depression as habitual – cued automatically by contextual cues, not goal-dependent and resistant to change – may be beneficial for future research and clinical applications. Abstract (Experimental Study) This study investigated predictions from the habit-goal framework for depressive rumination (Watkins & Nolen-Hoeksema, 2014) using a simultaneous replication single case experimental design in a multiple baseline case series. Seven high ruminators were recruited from community and university settings (with one participant’s data later excluded due to insufficient baseline rumination). Following a baseline monitoring period, participants received an intervention that included (i) spotting personal triggers for rumination and (ii) the practice of a scripted concrete thinking exercise (CTE) in response to these triggers, utilising an implementation intention (If-Then plan). It was predicted that practice of the IF-THEN CTE, linked to warning signs, would result in a significant reduction in both frequency and automaticity of rumination in the intervention phase compared to baseline. At the group level, using randomization tests (Onghena & Edgington, 2005), reductions in automaticity of rumination were trending toward statistical significance whilst the impact of the intervention on rumination frequency was not statistically significant. Effect size calculations, using nonoverlap of all pairs, demonstrated a medium effect of the intervention on automaticity (NAP = .76) and weak to medium effect on frequency of rumination (NAP = .66). Visual and statistical analysis of individual data demonstrated that two participants experienced statistically significant benefits (p < .05) for a reduction in automaticity of rumination and one participant’s frequency of rumination was significantly reduced. These two participants also showed the greatest levels of automaticity for the IF-THEN-CTE intervention during the intervention phase. Five participants demonstrated a strong or medium effect of the intervention on automaticity and two participants demonstrated a medium effect on frequency. Taken together, the data is broadly consistent with the predictions made by the habit-goal framework. Pre and post measures indicate reductions for all participants in rumination as habit using the self-report habit index (SRHI) and overall rumination levels rated on the ruminative responses scale (RRS). At post intervention three participants no longer met criteria for inclusion to the study on the RRS. Despite mixed results, feedback at debrief indicated that the intervention was acceptable to participants who reported that they would carry on using it after the study ended.

Extant research within competitive dynamics recognizes a positive relationship between high levels of competitive activity and firm performance, but the cognitive and psychological antecedents to competitive activity are far less clearly understood. I explore the role of a specific psychological antecedent - status, in impacting firms’ motivations to launch competitive moves against rivals. The key question, which extant literature does not seem fully equipped to answer, is when and under exactly what circumstances lower-status firms become motivated to launch action against higher-status ones and vice-versa. I use the stimulus-response model in social cognition to build theory which helps to answer the question by considering structural properties of market engagement. The specific structural property of market engagement that I focus on is market commonality, or the extent to which a rival is a significant player in markets important to a focal firm. I predict that a rival’s market commonality with a focal firm and its status relative to the focal firm have independent and positive effects on the extent to which the focal firm pays attention to the rival, that a rival’s market commonality with a focal firm and its status relative to the focal firm interact negatively to predict the focal firm’s motivation to launch action against that rival, and that a rival’s relative status and market commonality with a focal firm interact positively to predict the extent to which the focal firm pays attention to the rival. I test theory through a field study on gourmet food trucks in Lexington and an experiment through Amazon’s Mechanical Turk tool. Results provide broad support for the hypotheses. Three consequences follow from my study – that high-status firms are likely to come under attack from lower-status firms with whom they do not compete in markets, that they are unlikely to be paying attention to those lower-status firms when first attacked, and that they are likely to become aware of and motivated to act against those lower-status firms only after the lower-status firms have occupied key markets. My study contributes to the literatures in competitive dynamics, status, multi-market contact, and entrepreneurial action.

Stimulus-responsive colloidosomes which completely dissolve upon a mild pH change are developed. pH-Responsive nanoparticles that dissolve upon a mild pH increase are synthesized by a nanoprecipitation method and are used as stabilizers for a double water-in-oil-in-water Pickering emulsion. These emulsions serve as templates for the production of pH-responsive colloidosomes. Removal of the middle oil phase produces water-core colloidosomes that have a shell made of pH-responsive nanoparticles, which rapidly dissolve above pH 7. The permeability of these capsules is assessed by FRAP, whereby the diffusion of a fluorescent tracer through the capsule shell is monitored. Three methods for tuning the permeability of the pH-responsive colloidosomes were developed: ethanol consolidation, layer-by-layer assembly and the generation of PLGA-pH-responsive nanoparticle hybrid colloidosomes. The resulting colloidosomes have different responses to the pH stimulus, as well as different pre-release permeability values. Additionally, fundamental studies regarding the role of particle surface roughness on Pickering emulsification are also shown. The pH-responsive nanoparticles were used as a coating for larger silica particles, producing rough raspberry-like particles. Partial dissolution of the nanoparticle coating allows tuning of the substrate surface roughness while retaining the same surface chemistry. The results obtained show that surface roughness increases the emulsion stability of decane-water systems (to almost twice), but only up to a certain point, where extremely rough particles produced less stable emulsions presumably due to a Cassie-Baxter wetting regime. Additionally, in an octanol-water system, surface roughness was shown to affect the type of emulsion generated. These results are of exceptional importance since they are the first controlled experimental evidence regarding the role of particle surface roughness on Pickering emulsification, thus clarifying some conflicting ideas that exist regarding this issue.