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Response Selectivity as a Function of Developmental Activity LevelBeck, Wilford William, III 01 May 1975 (has links)
Research in hyperactivity has been primarily concerned with demon-strating casual relationships with cerebral dysfunction of the effects of drugs on improving learning performance. Studies which have attempted to focus on other factors influencing learning performance have demonstrated IQ and perceptual motor differences between hyperactive and normal children.
More recently Koegel and Covert have shown that, among a group of autistic children, over-selectivity of components from stimulus complex may adversely influence learning performance on a simultaneous discrimination task. There have been no demonstrations of this phenomena with hyperactive children.
The present study employed a simultaneous discrimination task composed of two stimulus complexes. Each complex in turn consisted of three geometric forms. Children were randomly selected, rated for activity level and then trained to respond reliably to specific complex. Once the discrimination to one of the complexes was established, the child was exposed to random pairs of components (one from the SD complex and one from the SΔ complex). Responses to either SD or SΔ were recorded.
A significant relationship was found between over-selectivity for one or more SD components as a function of increasing activity level. Response errors were found to be related to selectivity but not to activity level.
It would appear that performance deficits in learning a discrimination task may be, in part, related to over-selective focusing which results in failure to learn and hence, to integrate the entire stimulus complex.
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The behavior and separation of polystyrene in mixed solvent systemsHamilton, Patrick Neal 15 May 2009 (has links)
Non-polar phase selective solubility of modified poly(4-n-alkylstyrene) supports
can be measured using fluorescent dyes as catalyst surrogates with thermomorphic and
latent biphasic systems. By modifying the solvent compositions in heptane/ethanol and
heptane/N, N-dimethylacetamide, increased non-polar phase selective solubility of
modified polystyrene supports can be attained. Likewise, by varying the structure and
length of the pendant alkyl chain, an increase in non-polar phase selective solubility is
measured. These heptane soluble polymer supports can be useful for applications
involving heptane soluble polymer-bound reagents and catalysts.
Various polar and non-polar polymer supports were synthesized with an attached
solvatochromic catalyst surrogates to determine the solvent accessibility of the supported
species in pure and mixed solvents. The results of these studies indicate that in pure
solvents, the influence of both polar and non-polar polymer supports on the solvent
microenvironment of these polymer-supported probes is minimal. In mixed solvent
systems, a polymer-like solvent microenvironment is measured in solvent mixtures
comprised of solvents the polymer has unfavorable interactions. Poly(4-n-alkylstyrene)
and internally functionalized polyisobutylene supports are two such polymer supports that exhibit this behavior. For terminally functionalized polymers in mixed solvents, the
solvatochromic behavior does not indicate a collapsed structure. In mixed solvents,
there is minimal influence of the polymer support on the solvent microenvironment of
these terminally functionalized polymers.
The application of soluble polyisobutylene supported copper complexes in the
ATRP polymerization of styrene was investigated. Using the difference in solubility of
the product polystyrene and the polyisobutylene copper complex in heptane, a
solid/liquid separation of the soluble copper complex from the solid product was
achieved. The results of these polymerizations indicate that the polyisobutylene copper
complex behaves exactly like a low molecular weight copper complex in terms of
control over molecular weight and molecular weight distribution. After the
polymerizations, the polyisobutylene complexes could be separated as a heptane solution
and recycled in multiple polymerizations of styrene.
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Poverty and Migrant Selectivity in South-south Cross-border Migration : Evidence from CambodiaMolyaneth, Heng 28 March 2012 (has links)
No description available.
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May the force be with you : the influence of gatekeeping forces on the professional role conceptions of print and online newspaper journalists /Cassidy, William Patrick, January 2003 (has links)
Thesis (Ph. D.)--University of Oregon, 2003. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 238-251). Also available for download via the World Wide Web; free to University of Oregon users.
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Different time course of negative priming in the subtypes of ADHDShin, Misung 28 August 2008 (has links)
Not available / text
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An information-theoretic model of human search string selection in text editingAndes, Robert C. 12 1900 (has links)
No description available.
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Evaluation of a parent implemented intervention for food selectivity in children with autism.McKenzie, Emma Lee January 2012 (has links)
Food selectivity is a common problem in many children with Autism Spectrum Disorder (ASD). While research into this area is beginning to develop, there are currently few studies investigating the use of parent-implemented interventions within this population. The present study aimed to teach parents to implement multi-component behavioural interventions at home to ameliorate the food selectivity of their children. The study also aimed to show that these interventions could increase children’s preference for previously nonpreferred foods. Five children and their parents participated. The interventions delivered to the children were tailored to meet their needs and to fit within the context of their families. Each of these interventions was composed of antecedent, positive reinforcement and escape extinction strategies. Parents recorded their children’s food acceptance and disruptive behaviours during each intervention session. In addition, preference assessments were conducted in order to track changes in the children’s preferences for the target foods. The results showed that all of the parents were able to introduce at least one new food to their children’s diets during the intervention. Further, four of the five children showed an improvement in their preference for the targeted foods. These results were maintained at follow-up, although two of the children had only maintained some of the foods that had been introduced. All of the parents reported that their children consumed more foods at follow-up than they had during baseline and indicated that they thought the interventions had been effective. These results indicate that parents are able to implement multi-component behavioural interventions to increase the range of foods in their children’s diets and improve their children’s preference for these foods.
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Properties of absorbent polymer polymer extractants for the selective removal of target molecules from fermentation systemsDafoe, JULIAN 21 January 2014 (has links)
This thesis investigated polymer properties for their application as extractants in two-phase partitioning bioreactors (TPPBs), which are intended to remove inhibitory fermentation products as they are produced. Three applications of polymer TPPB extractants were studied, followed by an investigation into poly(ether)-based polymers’ affinity toward representative target molecules, to identify properties which confer improved extraction performance.
The first investigation aimed to replace a liquid extractant (silicone oil) using a block copolymer, Hytrel® 8206, in the biotransformation of indene to cis-(1S,2R)-indandiol, a chiral pharmaceutical intermediate, by Pseudomonas putida ATCC55687. The polymer simultaneously delivered substrate and removed the product and by-products to alleviate inhibition, improving operability and productivity relative to silicone oil, which could only deliver substrate. Subsequently, soft segment composition and proportion were varied in different block copolymers to selectively extract product or by-product(s) from the same biotransformation, altering the cells’ production profile. This demonstrated selective polymer extraction to help direct substrate utilization toward the product rather than by-product(s) in complex biotransformations.
The next study was on absorptive extraction of a hydrophilic target molecule, 4-valerolactone, produced by recombinant Pseudomonas putida KT2440, featuring an equilibrium-limited final step. The aim was to demonstrate the first application of equilibrium-pulling using selective product absorption, improving production by 30%. Furthermore, this study showed that limited polymer water absorption is helpful to aid in extraction of hydrophilic target molecules, but high polymer water content compromises selectivity, diminishing the equilibrium-pulling effect.
Finally, the effects of soft block proportion, molecular weight, and chain-end composition on affinity toward representative target molecules, carveol and carvone, were studied using commercial block copolymers and their representative homopolymer components. Target molecule affinity improved at low molecular weights in the absence of polar homopolymer end-groups. End-group polarity had an effect whose direction depended on the polarity of the target molecule, improving affinity toward a third, polar target molecule, 4-valerolactone, thereby providing a means to tailor selectivity. Crystallinity and hard segment proportion were both found to reduce uptake.
This work has provided insights into the selection of polymeric TPPB absorbents by identifying polymer properties which improve affinity and selectivity toward different fermentation target molecules, especially relatively hydrophilic ones. The future design of purpose-built polymer extractants will benefit from considering these findings. / Thesis (Ph.D, Chemical Engineering) -- Queen's University, 2014-01-17 13:43:54.818
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Visual space attention in three-dimensional spaceTucker, Andrew James. January 2006 (has links)
Thesis (PhD) - Faculty of Life and Social Sciences, Swinburne University of Technology, 2006. / Submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy, Faculty of Life and Social Sciences, Swinburne University of Technology - 2006. Typescript. "March 2006". Includes bibliographical references (p. 153-173).
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The neural basis of attention bias toward mood-congruent information in people with major depressive disorderLeung, Kwok-keung. January 2008 (has links)
Thesis (Ph. D.)--University of Hong Kong, 2008. / Includes bibliographical references (p. 113-141) Also available in print.
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