Identification and characterization of Myxococcus xanthus mutants deficient in calcofluor white binding.

In an attempt to further characterize the Cds phenotypes, it was found that SR171 (a Cds mutant) drastically reduced developmentally regulated tps gene expression similar to esg. Total fatty acid analysis revealed that SR171 is deficient in branched-chain fatty acids (BCFA). Addition of IVA to growing cells rescued fruiting body formation and increased sporulation and tps gene expression by several folds. SR171 differed from esg in pigmentation and sporulation. Extracellular complementation was observed when SR171 was mixed with wild-type and esg mutant. A 6kbp DNA fragment cloned from the wild-type cosmid library was able to partially complement genetically, the aggregation defect in SR171. Restriction analysis revealed that the SR171 locus was different from esg locus. The esg locus encodes the E1$\alpha$ and E1$\beta$ subunits of a branched-chain keto acid dehydrogenase (BCKAD) involved in the production of BCFA. The results suggest that SR171 locus appears to either encode for additional components of the BCKAD or components of a second enzyme involved in BCFA synthesis.The esg locus of Myxococcus xanthus was analyzed and shown to consist of two genetic complementation groups. In an attempt to characterize the defects in esg, it was found that the mutant bound the dye calcofluor white more poorly than wild-type cells. Unlike S-motility mutants that share this phenotype, esg exhibited S-motility. This led to the identification of nine new transposon insertion mutants, designated Cds (calcofluor white binding deficient, S-motile), which exhibited a phenotype similar to the esg strain. The Cds mutants were also found to be defective in cell-cell agglutination, polysaccharide production and developmental aggregation. The degree of polysaccharide deficiency in the Cds mutants correlated with the degree of loss of agglutination and dye binding as well as with the severity of the developmental aggregation defect. Extracellular matrix fibrils composed of roughly equal amounts of polysaccharide and protein have been shown to be involved in agglutination, and electron microscopic examination showed that esg and the other Cds mutants lack the wild-type level of fibrils. Preliminary genetic characterization demonstrated that the transposon insertion mutations in three of the Cds mutants (SR53, SR171, and SR200) were loosely linked

A Review of Virtual Reality Based Training Simulators for Orthopaedic Surgery

This review presents current virtual reality based training simulators for hip, knee and other orthopaedic surgery, including elective and trauma surgical procedures. There have not been any reviews focussing on hip and knee orthopaedic simulators. A comparison of existing simulator features is provided to identify what is missing and what is required to improve upon current simulators. In total 11 total hip replacement pre-operative planning tools were analysed, plus 9 hip trauma fracture training simulators. Additionally 9 knee arthroscopy simulators and 8 other orthopaedic simulators were included for comparison. The findings are that for orthopaedic surgery simulators in general, there is increasing use of patient-specific virtual models which reduce the learning curve. Modelling is also being used for patient-specific implant design and manufacture. Simulators are being increasingly validated for assessment as well as training. There are very few training simulators available for hip replacement, yet more advanced virtual reality is being used for other procedures such as hip trauma and drilling. Training simulators for hip replacement and orthopaedic surgery in general lag behind other surgical procedures for which virtual reality has become more common. Further developments are required to bring hip replacement training simulation up to date with other procedures. This suggests there is a gap in the market for a new high fidelity hip replacement and resurfacing training simulator

Contemporary design techniques for urban design: an inquiry into digital generative diagrammatic thinking

published_or_final_versionUrban Planning and DesignMasterMaster of Urban Desig

Analysis of current sense noise in a current mode-controlled flyback converter

M.S. (Master of Science