This research reports the results of experimental and numerical studies performed to characterize aerosol deposition on four different types of commercially available screens (electroformed-wire, woven-wire, welded-wire, and perforated-sheet) over a wide range of Stokes numbers (Stk ~ 0.08 to 20) and Reynolds numbers (ReC ~ 0.5 to 575). The objective of the present research was to use the results of the study to develop models and data that will allow users to predict aerosol deposition on screens. Three-dimensional Computational Fluid Dynamics (CFD) simulations using Fluent (version 6.1.22), as a tool, were undertaken and thus validating the numerical technique and then the result has been compared with the experimental data. For each type of screen, results showed that beginning at critical value of Stokes number where efficiency increased gradually to its maximum value that was almost asymptotic to the areal solidity. It is shown that data obtained from experimental and numerical studies for one particular type of screen would collapse to a single curve if the collection efficiency is expressed in terms of non-dimensional parameters. Correlations characterizing the aerosol deposition process on different types of screens were developed based on the above methodology. The utility of the developed procedure was demonstrated by considering an arbitrary test case, for a particular condition and reconstructing the efficiency curve for the test case. Further, results of the current study were compared with earlier researchers’ models (Landahl and Hermann, 1949; Davies, 1952; Suneja and Lee, 1974; Schweers et al., 1994) developed for aerosol deposition on fibrous filters and discussed. These results suggest that the aerosol collection characteristic on different models is different and depends on the nature of the manufacturing process for a typical model (wire or fiber). Finally, the pressure coefficient (Cp) for flow across the screen can be expressed as a function of the Reynolds number (ReC,f) and the fraction of open area (fOA). Correlations expressing the actual relationships were evolved. Additionally, a model was developed to relate pressure coefficient in terms of correction factor (OAfg) and Reynolds number.

This research reports the results of experimental and numerical studies performed to characterize aerosol deposition on four different types of commercially available screens (electroformed-wire, woven-wire, welded-wire, and perforated-sheet) over a wide range of Stokes numbers (Stk ~ 0.08 to 20) and Reynolds numbers (ReC ~ 0.5 to 575). The objective of the present research was to use the results of the study to develop models and data that will allow users to predict aerosol deposition on screens. Three-dimensional Computational Fluid Dynamics (CFD) simulations using Fluent (version 6.1.22), as a tool, were undertaken and thus validating the numerical technique and then the result has been compared with the experimental data. For each type of screen, results showed that beginning at critical value of Stokes number where efficiency increased gradually to its maximum value that was almost asymptotic to the areal solidity. It is shown that data obtained from experimental and numerical studies for one particular type of screen would collapse to a single curve if the collection efficiency is expressed in terms of non-dimensional parameters. Correlations characterizing the aerosol deposition process on different types of screens were developed based on the above methodology. The utility of the developed procedure was demonstrated by considering an arbitrary test case, for a particular condition and reconstructing the efficiency curve for the test case. Further, results of the current study were compared with earlier researchers’ models (Landahl and Hermann, 1949; Davies, 1952; Suneja and Lee, 1974; Schweers et al., 1994) developed for aerosol deposition on fibrous filters and discussed. These results suggest that the aerosol collection characteristic on different models is different and depends on the nature of the manufacturing process for a typical model (wire or fiber). Finally, the pressure coefficient (Cp) for flow across the screen can be expressed as a function of the Reynolds number (ReC,f) and the fraction of open area (fOA). Correlations expressing the actual relationships were evolved. Additionally, a model was developed to relate pressure coefficient in terms of correction factor (OAfg) and Reynolds number.

Dysphagia is a leading complication of a stroke. A nurse-driven bedside swallow screen can identify dysphagia and decrease the risk for complications such as aspiration pneumonia. At the project site, the use of the bedside swallow screen was at 33%; there was noncompliance with the use of the bedside swallow screen by the emergency department nurses. The purpose of the doctoral project was to increase the use of the bedside swallow screen. Published outcomes, research, and reports generated from archived data were the sources of evidence. The six sigma methodology was used to inform the quality improvement doctoral project. At the end of the quality improvement project, the posttest scores were statistically significantly higher than the pretest scores mean. The nurses' scores demonstrating level of confidence before the training (M = 68.39, SD = 10.86) were lower than scores indicating their level of confidence after the training (M = 79.55, SD = 10.56), and the paired t test showed statistical significance p < .001. The training made a statistically significant difference in the emergency department nurses' knowledge and confidence in performing the dysphagia screen. After the causes of low compliance were identified, strategies developed and implementation of the swallow screen in the emergency department increased. The quality improvement project improved the use of the dysphagia screen at the project site from 33% to 60%. The project made a positive impact on social change by reducing stroke patients' risk for complications.

The Roles of Presenilin and FKBP14 in Drosophila Development and Notch Signalling; Diana L. van de Hoef, Department of Molecular Genetics, University of Toronto, 2008. The multimolecular gamma-secretase complex cleaves type 1 transmembrane proteins such as Notch and one of the genes targeted in Alzheimer’s disease known as APP. This complex comprises four components, known as anterior pharynx defective 1, presenilin enhancer 2, nicastrin and presenilin. Presenilin is an aspartyl protease that comprises the catalytic core of gamma-secretase, and mutated forms of presenilin cause early-onset familial Alzheimer’s disease. To further define the role of Drosophila Presenilin (Psn), I performed a genetic modifier screen to identify Psn-interacting genes. One of the genes that was identified, known as FKBP14, encodes a peptidyl-prolyl isomerase that may be involved in protein folding in the ER. I demonstrate that an immunosuppressant drug known as FK506, which binds FKBPs and abrogates their function, reduced Psn, anterior pharynx defective 1 and presenilin enhancer 2 protein levels in vivo. I also show that FKBP14 colocalized with anterior pharynx defective 1 and Psn in the ER, suggesting a role in gamma-secretase stability. Consistent with this, I demonstrate that FKBP14 binds with Psn and mediates Psn stability and Notch signalling in vivo. To further characterize the role of FKBP14 in development, I analyzed its expression pattern and phenotypes of an FKBP14 null mutant. I show that FKBP14 localized to embryonic hemocytes and larval tissues, in addition to being expressed in developing egg chambers. FKBP14 function is required during development, since FKBP14 null mutants are recessive lethal. These mutants exhibited defects in larval disc development that resulted in eye, wing and notum phenotypes reminiscent of Psn dominant-negative and Notch-dependent phenotypes. Furthermore, FKBP14 mutants displayed enhanced apoptosis in larval tissues, suggesting a possible involvement in apoptosis regulation. I then examined the effects of FKBP14 overexpression, and observed enhanced Psn protein levels in vivo. Interestingly, co-expression of FKBP14 and Psn resulted in synergistic bristle phenotypes, suggesting a role for FKBP14 function in the Notch signalling pathway. Consistent with this, FKBP14 mutants enhanced Notch loss-of-function phenotypes in the wing. Altogether, my data demonstrate an essential role for FKBP14 during development, particularly in Psn protein maintenance and Notch signalling.

Thesis (M Med (Family Medicine))--University of Limpopo (Medunsa Campus),2010. / BACKGROUND: Common preventable causes of maternal and perinatal mortality such as HIV, anaemia, gestational proteinuric hypertension, syphilis and Rhesus disorders can be identified early with simple antenatal screening, however this screening is not always efficiently and effectively done. It is critical to identify challenges and possible solutions to ensure effective implementation of the national antenatal screening guidelines for these conditions. Even within existing inadequate resources, there is always room for improved efficiency. METHODS: The aim of this study was to evaluate the implementation of the national guidelines for antenatal screening in the Acornhoek district, Mpumalanga. It was a prospective, cross-sectional study of the antenatal screening programme in the Acornhoek district. Data was collected from an analysis of antenatal and medical records of all women who received antenatal care in the Acornhoek district and ultimately delivered at Tintswalo Hospital, Acornhoek, during the study period of one calendar month. Standardised questionnaires were administered at each of the 15 antenatal clinics referring to Tintswalo Hospital to identify the challenges preventing the effective implementation of the national guidelines for antenatal screening that were experienced by the nurses at the clinics. RESULTS: 428 women were interviewed post partum. 335 were included in the study (87 had received antenatal care out of the district and 6 were unbooked). 85.7% of women had been tested for syphilis antenatally, 84.8% had been tested for anaemia, 72.8% had had blood taken for Rhesus factor and only 64.2% had had pre-test counselling for HIV. 14.3% of women did not have their blood pressure checked at every visit and over 31.4% did not have urine dipstick tests done at every visit. 27% of women booked before 20 weeks, however only 18% had their antenatal bloods taken before 20 weeks. Of the women who had had antenatal blood screening tests done, 18% had not received results by the time of delivery. There was considerable variation between the clinics. Challenges preventing the effective implementation of antenatal screening included variation in knowledge of antenatal screening requirements by clinic staff, barriers to HIV testing, poor infrastructure, equipment and supply problems, laboratory support issues, onsite testing challenges, poor support from the district and passive response to problem solving by clinic staff. CONCLUSIONS: Not all women receiving antenatal care in the Acornhoek district are being screened for HIV, anaemia, GPH, syphilis and Rhesus disorders. From the reasons identified above, interventions such as in-service training of clinic staff in antenatal screening, removing barriers to HIV testing such as appointing lay counsellors at every clinic and offering provider driven or opt-out testing for HIV, improving infrastructure such as installing telephones at every clinic, increasing the laboratory courier service to 5 days a week, introducing on site testing of syphilis, anaemia and Rhesus factor and a rapid pro-active approach to problem solving by district and clinic staff to manage barriers to antenatal screening such as broken equipment and out of stock supplies.

Nitriding is a plasma based processing technique that is used to improve the surface properties of components and products in many areas including the aerospace, automotive and biomedical industries to name a few. Active Screen Plasma Nitriding (ASPN) is a relatively new nitriding technique which has potential advantages over the more traditional nitriding techniques such as Direct Current (DC) plasma nitriding where high substrate biases can be problematic. However, there is considerable debate as to the mechanism for nitriding in ASPN. This thesis focuses on investigating the mechanism for nitriding in a commercial ASPN system. Commercial ASPN treatments of nitrideable alloy steels were found to be unsatisfactory unless a sufficient bias was applied. The level of bias required to produce a satisfactory nitriding response, in terms of the cross sectional hardness, was found to depend on the concentration of strong alloy nitride forming elements present in the steel. Although active screen material was found to be transferred to the workload, no evidence was found that this process played a significant role in enhancing the nitriding response. The primary mechanism for nitrogen mass transfer in ASPN was found to be dependent on the active screen/workload separation distance. When this separation is small (less than approximately 10cm for the conditions used in this study) then nitrogen mass transfer in the form of energetic ions or neutrals can occur between the active screen and the workload. This allows samples to be treated without a substrate bias. On the other hand, when the active screen/workload separation distance is large (greater than approximately 10cm) as is normally the case in a commercial environment, this mechanism for nitrogen mass transfer breaks down and a substrate bias is essential. In this latter case, nitrogen ions attracted to the workload using a bias is the primary nitrogen mass transfer mechanism and the role of the active screen is primar ily to uniformly heat the workload.

In the imaging system, a blurred defocus image is a common problem. This is because different objects in the scene need different focus for imaging clearly. Background¡¦s focus distance is different to the objects. However, we can only have one focus distance in one picture. Therefore, the images of the other objects in different focus distance would be blurred by the faulty focuses. We solve the above defocus problem by wave front coding. Wave front coding is a technique that adds a phase mask in front of the lens, changing the image performance. In this thesis, we used a ring phase screen, computed accordingly its optical transfer function and then simulated the resulting images. We compared with other phase screens provided by other researchers for different defocus situations. From our simulated images and OTF results, our ring phase pupil is slightly superior.

The key to an efficient screening method is the ability to screen large amounts of plant material in the shortest time possible. Unfortunately, due to the complexity of drought tolerance, a quick and effective screen for this trait has yet to be established. The research reported herein was designed to evaluate a screening method for drought tolerance in cotton (Gossypium hirsutum L.) seedlings. Twenty-one converted race stocks (CRS) and two cultivars were evaluated for seedling drought tolerance on an individual plant basis. CRS are day-sensitive primitive lines derived from various wild race stocks that were converted to day neutrality for use in temperate region plant improvement programs (McCarty et al., 1993). Genotypes were evaluated October - November 2004 and February - March 2005 under greenhouse conditions at the Norman E. Borlaug Center for Southern Crop Improvement, College Station, TX. Seedlings were subjected to three sequential cycles of drought at 15 days after planting (DAP). Drought cycles consisted of withholding water until the moisture content of "indicator" cone-tainers, containing Deltapine 491 (DP 491), had an average volumetric water content of 0.07. Plants were then watered to field capacity and percent survival was recorded after 48 hours. Genotypes differed in their percent survival following three consecutive drought cycles. Drought cycles 2 and 3 did not contribute to the separation of genotypes. DP 491 was the most tolerant genotype evaluated. None of the CRS were more or less tolerant than Acala 1517-99. CRS M-9044-0165 was the most stable genotype across the two experiments.

The main purpose of this study was to determine the effect of contour height on the passage ratio of pulp through screen apertures, and determine which operating variable has the greatest affect on screen performance. In addition, a freeness model was to be developed, in hopes of helping to predict the freeness drop between feed and accepts. The study was conducted at The University of British Columbia (UBC) using a laboratory scale pressure screen. Slot velocity, feed consistency and contour height were the changing variables. Samples were collected from which passage ratio, freeness, fibre length and coarseness were determined. From the studies conducted it was found that slot velocity had the greatest influence on the screen operation. As the slot velocity increased a greater force was applied to the fibre to help push it through the screen aperture. However, this increase in slot velocity decreases the fractionation ability (separation of fibres into different lengths) of the screen. The second most important variable was the contour height. The main function of the contour height is to disrupt the flow of thick stock at the wall of the screen and allow for unhindered movement of fibre to the screen wall. The greater the contour height is, the greater the passage ratio (pulp fibre passing through screen). However, there is a decrease in fractionation. The third most important factor was the feed consistency. At low feed consistencies there is less crowding in the screen. Less crowding leads to more loosely-formed flocs, which are easier for the contour height and the rotor to dissipate and thus leads to unhindered movement. Thicker feed stock has a negative effect on passage A Freeness model was developed that showed that freeness had a power law relationship to passage ratio. The passage ratio was raised to a constant B, which is a function of the contour height and the feed consistency.

Prion diseases are invariably fatal proteinaceous neurodegenerative disorders of the central nervous system. The infectious agent is the host encoded prion protein which has undergone a post-translational refolding from a predominantly alpha-helical to highly beta-sheet containing structure. The mechanism of prion-induced neurotoxicity remains elusive in large part due to the absence of a sufficiently neurotoxic cell culture assay. A modern technique for identifying previously unrecognized mediators of a biological pathway is to screen a commercially available library of gene silencing molecules targeting all known open reading frames. Synthetic gene silencing molecules, such as short hairpin RNA (shRNA), employ the endogenous gene silencing pathway to inhibit protein synthesis. To date, no publication has described the implementation of a large-scale library to screen for genetic mediators of prion neurotoxicity. This project was aimed at developing a cell culture model of acute prion neurotoxicity and screening a library of shRNA molecules in order to identify previously unrecognized gene targets essential to prion-induced neurotoxicity. Using a fragment of the prion protein (PrP106-126 peptide) to mimic prion neurotoxicity, human neuroblastoma cells transduced with a retroviral shRNA library were screened for resistance. Involvement of a subset of library identified gene targets in prion disease was assessed in vivo by quantitative real-time PCR (qPCR) analysis. Validation of the protection conferred by reducing expression of a gene target of interest was accomplished using individual lentiviral vectors expressing shRNA. Of the approximately 54,000 shRNA sequences screened, 80 different shRNA sequences recovered from neurotoxic prion peptide-resistant cells were considered to be of interest. Of these, 49 corresponding gene targets were assessed in vivo by qPCR with the majority demonstrating significant differential expression in brains of prion infected mice. Validation of the protection conferred from knockdown of two identified genes, abcb4 and ube2cbp, was completed. Knockdown of either gene imparted significant protection against prion-induced neurotoxicity, with qPCR analysis confirming significantly reduced mRNA transcript levels. Overall, the validity of the novel assay system developed has been demonstrated, and the first comprehensive list of gene candidates involved in mediating acute prion neurotoxicity has been determined.