Splotch (Sp) is a semidominant mouse mutant which maps to the proximal portion of chromosome 1 and is phenotypically expressed as a pleiotropic defect during neurogenesis, resulting in spina bifida, exencephaly and dysgenesis of neural crest cell derivatives. To identify the aberrant gene underlying the defects observed in the Sp mouse mutant we initiated positional cloning strategy. Our preliminary efforts were directed at establishing the boundaries of a deleted chromosomal segment found in the Sp$ sp{r}$ allele, using nine gene probes that were assigned to that region of chromosome 1. Four of these genes, Vil, Des, Inha, and Akp-3, spanning a genetic distance of approximately 15 cM, were found to map within the Sp$ sp{r}$ deletion. In order to further delineate the subchromosomal location of the Sp gene, the proximal segment of mouse chromosome 1 was saturated with microclones isolated from a library of microdissected genomic fragments generated from this region. An additional eight markers were found to map within the confines of the Sp$ sp{r}$ deletion. / During the course of this work a member of the paired box gene family, Pax-3, was described as a candidate for Sp. The striking similarity between the tissue distribution of Pax-3 mRNA in normal developing embryos, and the neural structures affected in Sp mice, together with the chromosome 1 location of Pax-3 led us to examine whether Pax-3 was mutated in three alleles at this locus Sp$ sp{r}$, Sp$ sp{2H}$ and Sp. The entire Pax-3 gene was determined to be deleted in the Sp$ sp{r}$ allele. Analysis of genomic DNA and cDNA clones constructed from RNA isolated from $Sp sp{2H}/Sp sp{2H}$ embryos identified a deletion of 32 nucleotides within the paired type homeobox and is predicted to produce a truncated protein as a result of a newly created termination codon at the deletion breakpoint. The original Sp allele was also characterized and found to contain an A to T transversion at position -2 in the third intron of Pax-3 which abrogates the normal splicing of this intron due to the loss of its natural 3$ sp prime$ splice acceptor. Taken together, these studies indicate that the severe defect in neural tube formation detected in Sp and its allelic variants is linked to the inactivation of the paired box gene Pax-3, and provides direct genetic evidence of a key role for Pax-3 in normal neural development.

An experimental and numerical study of air-air bent exhaust ejectors was carried out. The objective of the study was to determine the effect of a bend on the performance of exhaust ejectors. The ejectors consisted of nozzles, mixing tubes and in some cases entraining diffusers. As part of this study the effect of swirl in the primary flow and the temperature ratio of the primary to the secondary flow were also investigated. The study included testing of round and oblong sectioned ejectors with and without entraining diffusers. The experimental testing was performed on two different wind tunnels capable of blowing air at a maximum mass flow rate of 2.2 kg/s at ambient and elevated temperatures. Flow measurements were made upstream of the nozzle, at the nozzle exit and at the exit of the ejector. Pumping, pressure rise and total efficiency of the ejector were studied with respect to the bend angle, swirl angle and the primary to secondary flow temperature ratio. A commercial CFD code was used to evaluate the effectiveness of commercial CFD using limited resources for designing of such devices. The pumping ratio and pressure rise decrease with the increase in the degree of bend. Swirl up to a certain angle has a useful effect on the performance of a bent ejector. The entraining diffuser enhances the performance of a bent ejector. The CFD models based on commercial solver were able to predict the flow structures and the variation of the performance parameters with the bend and swirl angle. However, generally the CFD models were not able to predict the exact values of the performance parameters. / Thesis (Ph.D, Mechanical and Materials Engineering) -- Queen's University, 2008-03-31 05:53:54.89 / NSERC DND WR Davis

No description available.

Genetic linkage studies of the spontaneously arising splotch allele, Sp, were conducted to identify closely linked molecular markers as a preliminary step for the isolation of the mutant gene. Restriction fragment length polymorphism and microsatellite size variation analyses were employed to follow the segregation of Sp in relation to eight or ten loci previously assigned to the proximal portion of mouse chromosome 1. Although results from an interspecific ((Sp/+ x Mus spretus)F1-Sp x C57BL/6J) backcross study were inconclusive, a panel of 125 intraspecific ((Sp/+ x CBA/J)F1-Sp x CBA/J) backcross mice positioned the Sp gene 0.8 $ pm$ 0.8 centiMorgans distal to the Vil/Des/Inha loci and detected no recombinant between the mutant allele and the murine paired box gene, Pax-3, positioning this locus within 2.9 centiMorgans of Sp (95% confidence limits). Concurrent research has identified alterations in Pax-3 in several Sp allelic variants; thus, this study provides additional genetic evidence in support of the candidacy of Pax-3 for the Sp locus. Effects of genetic background on the penetrance and expression of Sp were also observed.

During a loss of coolant accident in a pressurised water reactor, emergency core cooling water is introduced via the downcomer annulus. The water may have to penetrate or overcome steam formed in the vessel due to the depressurisation. A typical counter-current flow situation can be created and dependent on the relative flow rates water may be prevented from reaching the reactor core with serious consequences. This,thesis considers the events leading up to this occurrence in a vertical, 54.75 mm diameter, 1 m long, stainless steel tube, to represent and provide a basic understanding of the situation occurring during a loss of coolant accident. Results are presented for air-water and steam-water flows with emphasis on the experimental and theoretical studies of the steam-water flow situation where direct contact heat transfer occurs. The air-water flooding data are shown to be well represented by a Wallis type flooding correlation. The steam-water flooding data are found to lie above the corresponding air-water data with their characteristic dependent on the water inlet subcooling. The percentage of the air/steam flow extracted with the water flow at the bottom porous sinter was found to exert a negative effect on the flooding phenomena. A theoretical model was developed to predict the liquid film thickness along the tube, and agreement with the experimental results demonstrated. A second theoretical model was developed to evaluate the temperature across the liquid film and along the test tube and from this model, the effective turbulent diffusivity was evaluated, leading to an estimate of the turbulent viscosity of the film under conditions in which substantial condensation took place. A semi-empirical model based on a linear stability analysis of a uniform liquid film and a counter-current flow of steam, was developed and modified for accelerating film flows. This model is shown to be capable of dealing with the steam-water flooding situation since reasonable agreement with the air-water flooding data is obtained. A modified Wallis type flooding correlation based on the experimental data, and accounting for non-equilibrium effect on flooding, is presented and discussed. A visualisation technique was developed and used to determine the flooding location in the section.

Thesis (Ph. D.)--University of Adelaide, Dept. of Horticulture, viticulture and ocnology, 1996. / Copy of author's previously published article inserted. Includes bibliographical references (leaves 127-154).

Thesis (Ph. D.)--Washington State University, December 2008. / Title from PDF title page (viewed on Jan. 22, 2009). "School of Biological Sciences." Includes bibliographical references.

Thesis (Ph. D.)--University of Missouri-Columbia, 2008. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on August 4, 2009) Vita. Includes bibliographical references.

Thesis (Ph. D.)--Ohio State University, 2004. / Title from first page of PDF file. Document formatted into pages; contains xiv, 111 p.; also includes graphics (some col.). Includes bibliographical references (p. 98-111). Available online via OhioLINK's ETD Center

Thesis (M.S.)--University of Wisconsin--Madison, 1965. / eContent provider-neutral record in process. Description based on print version record. Bibliography: l. 66-68.