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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.
1

Order and disorder: a hotel in Alexandria, Virginia

Walliser, Claude René January 1995 (has links)
The main theme to investigate repetitive elements included an investigation into the limits of monotony and an addition of an exception to their rank, that is why the design for a hotel has been chosen. The secondary theme to crystallize my beliefs about urban design was possible by choosing a site of inherent complexity in a diverse context. / Master of Architecture
2

A comparison of visual and memory search processes within a single task

Weiss, Regina Ann January 1978 (has links)
The present information processing research provided a comparison of visual search and memory search processes with respect to search rates and search strategies. An innovative paradigm was evaluated which varied search type (i.e., visual or memory) randomly between trials of a single choice reaction time (RT) task. The following sequence of events for each of the 280 trials occurred. A ''memory" list of letters appeared, which subjects (N = 12) turned off by pulling simultaneously a left and right-hand RT trigger. After 3 sec, a warning buzzer sounded followed by a variable interval ranging from .5 to 1 sec and the "recognition" list. The subject pulled the left or right-hadn trigger as quickly as possible to indicate whether the memory and recognition lists included the same letter. A single target letter appeared as the memory list on the 140 visual search trials and as the recognition list for the 140 memory search trials. The search set (presented either as a memory list or recognition list) contained three, five, or seven letters. Memory Search was faster and less accurate than was Visual Search in the present task, The RT slope and serial position data indicated that Visual Search involved a serial, self-terminating comparison process, whereas the Memory Search data confirmed Sternberg's serial, exhaustive model. It was noted that physical characteristics of the task could have biased Visual Search toward a self-terminating strategy. Suggestions for future research in this area were discussed, as well as the author's plans to apply the paradigm to the study of information processing deficits in learning disabled children. / Master of Science
3

Tumor-induced macrophage and T cell dysfunction

Walker, Thomas M. 27 February 2007 (has links)
Macrophages (MΦ) and T cells mediate helper, effector, and cytotoxic activities. Tumor growth changes the phenotypic and functional characteristics of MΦ and T cells and shifts them toward suppressor phenotypes and functional activities. Tumor growth changed MΦ DNA synthesis when activated through Mac-1 and Mac-3 surface molecules, which suggests that specific receptor-ligand interactions modulate MΦ cell-cycle kinetics differently in the tumor-bearing host (TBH). Tumor growth changed MΦ responsiveness to MΦ colony-stimulating factor (M-CSF). M-CSF did not reverse decreases in autorecognition caused by TBH MΦ, and increased TBH MΦ suppression during T-cell alloreactivity. TBH suppressor activities were associated predominantly with MHC class II MΦ. TBH class II⁻ MΦ quantitatively and qualitatively suppressed T-cell autoreactivity partly by dysregulation of interferon-gamma (IFN-y), interleukin-4 (IL-4), and prostaglandin E₂ (PGE₂) production. TBH MΦ had aberrant regulation of granulocyte-macrophage colony-stimulating factor (GM-CSF). TBH MΦ produced less GM-CSF than normal host (NH) MΦ. GM-CSF failed to increase class II molecule expression on TBH MΦ, and TBH class II⁻ MΦ became more suppressive when cultured with GM-CSF. TBH MΦ GM-CSF dysregulation involved PGE₂ and interleukin-10 (IL-10). Tumor growth also affected CD4⁺ and CD8⁺ T cell phenotype and function. The in vivo percentage of CD8⁺ T cells significantly increased during tumor growth and these cells significantly suppressed T-cell allorecognition and autorecognition. TBH CD8⁺ T-cell suppression was mediated partly through dysregulation of IFN-y, IL-4, and PGE₂ production. TBH CD4⁺ T cells produced less GM-CSF than NH CD4⁺ T cells, and GM-CSF dysregulation was linked partly to increased sensitivity to IL-10 and transforming growth factor-β₁ (TGF-β₁). Tumor growth changed CD4⁺ T cell responsiveness to cytokines associated with T cell activation. TBH CD4⁺ T cell proliferation was suppressed significantly by taxol. This research also suggests that taxol can promote tumor regression. Taxol disrupted tumor cell growth through cytostatic and cytotoxic mechanisms, and increased tumor cell susceptibility to taxol-induced, MΦ-derived lytic molecules. Taxol also disrupted autocrine regulation of TGF-β₁ and stimulated apoptosis. Collectively, these studies suggest that tumor-associated changes in MΦ and T cells involve cytokine dysregulation. |Immunotherapeutic approaches may partly or completely reverse suppressor immune cell activities during tumor growth. / Ph. D.
4

Experimental anaerobic bacterial infections in mice

Walker, Clay B. 01 August 2012 (has links)
The development of a technique for producing a pure Bacteroides fragilis infection in mice is described. The infection produces large subcutaneous abscesses at the site of bacterial injection in approximately 90% of the mice. The abscess can be seen as an obvious swelling within 5-7 days post-injection. The infection was initiated by injection of pure cultures grown in a semisolid medium. Similar infections were also produced with pure cultures of B. distasonis, B. ovatus, B. thetaiotaomicron, and B. vulgatus. / Ph. D.
5

Die Aminosäuren W355 und A359 des rOCT1 zeigen substratabhängige Mutationseffekte und ändern nach Mutation die Affinität des Transporters zu TBuA / The amino acids W355 and A359 of rOCT1 show substrate-dependent mutation effects and change the affinity of the transporter to TBuA

Aichner, Christian January 2014 (has links) (PDF)
Die Aminosäuren W355 und A359 des rOCT1 zeigen substratabhängige Mutationseffekte und ändern nach Mutation die Affinität des Transporters zu TBuA / The amino acids W355 and A359 of rOCT1 show substrate-dependent mutation effects and change the affinity of the transporter to TBuA
6

The effect of variations in procedure on the yield and moisture content of cheddar cheese

Wall, H. F. January 1920 (has links)
Master of Science
7

Exemplary career development practices of Virginia's middle schools

Wallace, Debbie Webb 05 October 2007 (has links)
The National Occupational Information Coordinating Committee (NOICC) ( 1989) has defined career development guidelines for all groups from elementary school students through adulthood. These guidelines have been adopted by over 40 states. Virginia has chosen not to adopt them and currently does not have state standards against which to identify or assess exemplary career development practices in middle schools. Such identification procedures would serve to (a) provide guidelines for program development and expansion, (b) provide a means of accountability, ( c) provide a standard of performance, ( d) provide consistency among middle schools, and ( e) showcase exemplary programs. This study examined exemplary career development practices at 43 middle schools in Virginia during the Fall of 1996. The researcher identified these schools by asking for recommendations from State Department of Education Field Representatives, university faculty with expertise in the fields of counseling, middle school education or both, and current and most recent past officers of the Virginia Counselors Association and the Virginia School Counselor Association. A survey method was used to identify general curriculum design, physical facilities, technological capabilities, activities and strategies used to incorporate career development into the curricula of the identified middle school. Three site visits and one in-depth telephone interview were conducted by the researcher to verify exemplary career development practices. The following common themes were found concerning exemplary career development practices: <ol> <li>There were teacher-advisory programs in which a variety of career development activities took place in the academic classrooms.</li> <li>There were middle school teams in which groups of teachers worked together on career development activities which were integrated into the core curriculum through these teaming efforts.</li> <li>There were curriculum design efforts in which career development exploratory classes were offered on either a 6, 9, 12, or 18 week rotation.</li> <li>There were special interest clubs, many of which directly related to career development. </li> <li>There were classroom guidance activities conducted by counselors related to career development. </li></ol> Evaluations of the Survey findings, recommendations and conclusions of this study were reported in the hope that middle school career development programs in Virginia's middle schools will strive for exemplary practices for the benefit of their own students. / Ed. D.
8

Plant diversity and its effects on populations of cucumber beetles and their natural enemies in a cucurbit agroecosystem

Walker, Jason 22 August 2008 (has links)
Populations of striped cucumber beetles (<i>Acalymma vittatum</i> Fabr.), spotted cucumber beetles (<i>Diabrotica undecimpunctata howardi</i> Barber), western cucumber beetles (<i>Acalymma trivittatum</i> Mann.), Pennsylvania leatherwings (<i>Chauliognathus pennsylvanicus</i> DeGeer), Diptera (Order: Diptera), lady beetles (Order: Coleoptera, Family: Coccinellidae), hymenoptera (Order: Hymenoptera), and spiders (Order: Araneae) in a cucumber field and a bordering field of uncultivated vegetation were assessed using yellow sticky traps to determine: 1) the relative abundances of target insects across the uncultivated vegetation and the crop field, 2) relationships between target insects and plant species. In both years populations striped and spotted cucumber beetles and Pennsylvania leatherwings (only in 1995) increased significantly and Diptera decreased significantly in the direction of the crop. The strength of these relationships increased over the season to a peak in August in 1995 and July in 1996 and then decreased in September in both years. There were significant correlations between Diptera and sweet-vernal grass in 1995. In 1996, cucumber beetles were correlated with wild violet (<i>Viola</i> spp.) and white clover (<i>Trifolium repens</i>); Diptera with wild violets; and the lady beetle <i>Coleomegilla maculata</i> with goldenrod (<i>Solidago</i> spp.), English plantain (<i>Plantago lanceolata</i>), and marjoram (<i>Origanum</i> spp.) in 1996. This study demonstrated the potential value of increasing the diversity of a cucumber field to control insect pests (and thus reduce pesticide useage) as well as suggested specific plants that influenced insect populations. / Master of Science
9

The development of chemical curricula in the United States

Walker, Charles B. January 1910 (has links)
Master of Science
10

Investigation of induced strain actuator patches implementing modeling techniques and design considerations to reduce critical stress

Walker, John Griffith 04 March 2009 (has links)
One of the major problems with surface-mounted or embedded induced strain actuator (ISA) patches are the considerably high stress gradients introduced at the edges of the actuator patches when an electric field is applied. These excessive stress gradients initiate debonding of the actuators from the substrate, thus affecting the mechanical reliability of the structure. This thesis is begun by investigating existing theoretical models of induced strain actuated structures, and will later use these to compare with the finite element analysis. The finite element analysis is used to explore the stress concentrations located at the edges of the actuators and begins by refining the mesh areas of the same structure focusing in on the ends of the ISA’s. This preliminary analysis is conducted on a structural configuration with a perfectly bonded actuator and proceeds to one with a finite bonding layer. After completion of the mesh refinement investigation several modifications in the design and implementation of the induced strain actuators are examined to reduce the stress concentrations at the edges of the actuators. In the finite element analysis two separate modeling considerations are examined: 1) The actuator is perfectly-bonded to the substrate. 2) A finite adhesive layer is incorporated between the actuator and the substrate. With each modeling consideration several design modifications are considered in this thesis including employing partial electrodes on the induced strain actuator surface regions instead of fully electroded surfaces, examining an actuator with a chamfered end, and using caps to reduce the stress concentrations and possibly increase the performance of the structure by allowing the induced strain actuators to utilize their piezoelectric strain coefficient in the thickness direction, d₃₃. The design modifications and different modeling techniques help to alleviate the critical stresses in the structure while gaining a better understanding of causes them. / Master of Science

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