The influence of condenser pressure variation and tip leakage on low pressure steam turbine exhaust hood flows

This paper aims to highlight the importance of the accurate computational modelling of both the inlet and outlet exhaust hood boundary conditions. The computations presented are calculated using the public domain low pressure exhaust diffuser test case proposed by Burton in 2012. The original test case did not include the effect of tip leakage on diffuser flows, but this paper describes the inclusion of tip leakage and the results are shown to be in line with the outputs produced by other authors. The key advance in this paper is that calculations were conducted with a representative condenser pressure gradient caused by the temperature variation inside the condenser tube nest. It is shown that accurately modelling the exit boundary calculation has a large influence on the flow structure and a smaller influence on the pressure recovery inside the exhaust diffuser. This influence is smaller than that seen by other authors when including unsteady effects or accounting for the circumferential non-uniformity of the turbine exit flow but will need to be included in design calculations as diffuser design advances

Comparative Efficiency Assessment of Primary Care Models Using Data Envelopment Analysis

This paper compares the productive efficiencies of four models of primary care service delivery in Ontario, Canada, using the data envelopment analysis (DEA) method. Particular care is taken to include quality of service as part of our output measure. The influence of the delivery model on productive efficiency is disentangled from patient characteristics using regression analysis. Significant differences are found in the efficiency scores across models and within each model. In general, the fee-for-service arrangement ranks the highest and the community-health-centre model the lowest in efficiency scoring. The reliance of our input measures on costs and number of patients, clearly favours the fee-for-service model. Patient characteristics contribute little to explaining differences in the efficiency ranking across the models.Productive Efficiency; DEA; Primary Health Care

Understanding Somatic Mosaicism in Myotonic Dystrophy Type 1

Myotonic dystrophy type 1 is caused by an unstable CTG repeat expansion in the 3' UTR of the DM1 protein kinase gene on chromosome 19. A neuromuscular disease with a broad spectrum of symptoms, DM1 also exhibits anticipation whereby disease severity increases through successive generations. Increasing measured allele size between patients correlates with an increased severity of symptoms and an earlier age of onset. However, this correlation is not precise and therefore measured allele length caimot be used as an accurate indicator of age of onset. This suggests that repeat length may not be the major determinant of disease severity. There is a high level of somatic mosaicism shown by the mutation and failure to take into account age-dependent somatic mosaicism in patients may have compromised the accuracy of clinical correlations. The aim of this project was to investigate simple approaches for correcting for age-dependent somatic mosaicism and also to develop computer software to allow us to simulate the progression of age-dependent somatic mosaicism. We have demonstrated that employing alternative approaches in both molecular diagnoses and statistical comparison can yield significantly improved repeat length / age of onset correlations. This conclusively shows that repeat length is by far the major determinant in DM1 disease onset. Simulation software was also successfully developed and preliminary results suggest that DM1 repeat instability is amenable to mathematical modelling in the future

Transcriptomic response of maize primary roots to low temperatures at seedling emergence

peer-reviewedBackground Maize (Zea mays) is a C4 tropical cereal and its adaptation to temperate climates can be problematic due to low soil temperatures at early stages of establishment. Methods In the current study we have firstly investigated the physiological response of twelve maize varieties, from a chilling condition adapted gene pool, to sub-optimal growth temperature during seedling emergence. To identify transcriptomic markers of cold tolerance in already adapted maize genotypes, temperature conditions were set below the optimal growth range in both control and low temperature groups. The conditions were as follows; control (18 °C for 16 h and 12 °C for 8 h) and low temperature (12 °C for 16 h and 6 °C for 8 h). Four genotypes were identified from the condition adapted gene pool with significant contrasting chilling tolerance. Results Picker and PR39B29 were the more cold-tolerant lines and Fergus and Codisco were the less cold-tolerant lines. These four varieties were subjected to microarray analysis to identify differentially expressed genes under chilling conditions. Exposure to low temperature during establishment in the maize varieties Picker, PR39B29, Fergus and Codisco, was reflected at the transcriptomic level in the varieties Picker and PR39B29. No significant changes in expression were observed in Fergus and Codisco following chilling stress. A total number of 64 genes were differentially expressed in the two chilling tolerant varieties. These two varieties exhibited contrasting transcriptomic profiles, in which only four genes overlapped. Discussion We observed that maize varieties possessing an enhanced root growth ratio under low temperature were more tolerant, which could be an early and inexpensive measure for germplasm screening under controlled conditions. We have identified novel cold inducible genes in an already adapted maize breeding gene pool. This illustrates that further varietal selection for enhanced chilling tolerance is possible in an already preselected gene pool

Polarized Radio Sources: A Study of Luminosity, Redshift and Infrared Colors

The Dominion Radio Astrophysical Observatory Deep Field polarization study has been matched with the Spitzer Wide-Area Infrared Extragalactic survey of the European Large Area Infrared Space Observatory Survey North 1 field. We have used VLA observations with a total intensity rms of 87 microJy beam^-1 to match SWIRE counterparts to the radio sources. Infrared color analysis of our radio sample shows that the majority of polarized sources are elliptical galaxies with an embedded active galactic nucleus. Using available redshift catalogs, we found 429 radio sources of which 69 are polarized with redshifts in the range of 0.04 < z <3.2. We find no correlation between redshift and percentage polarization for our sample. However, for polarized radio sources, we find a weak correlation between increasing percentage polarization and decreasing luminosity.Comment: 35 pages, 12 figures, accepted for publication in The Astrophysical Journa