60 resultados para Kirk, Bernard

em University of Queensland eSpace - Australia


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This paper is a foreword to a series of papers commissioned on 'the impact of science on the beef industry', where the Beef CRC-related collaborative scientific work of Professor Bernard Michael Bindon will be reviewed. These papers will be presented in March 2006, as part of a 'festschrift' to recognise his wider contributions to the Australian livestock industries for over 40 years. Bindon's career involved basic and applied research in many areas of reproductive physiology, genetics, immunology, nutrition, meat science and more recently genomics, in both sheep and cattle. Together with his collaborators, he made large contributions to animal science by improving the knowledge of mechanisms regulating reproductive functions and in elucidating the physiology and genetics of high fecundity livestock. His collaborative studies with many colleagues of the reproductive biology and genetics of the Booroola Merino were amongst the most extensive ever conducted on domestic livestock. He was instrumental in the development of immunological techniques to control ovulation rate and in examining the application of these and other techniques to increase beef cattle reproductive output. This paper tracks his investigations and achievements both within Australia and internationally. In the later stages of his career he was the major influence in attracting a large investment in Cooperative Research Centres for the Australian cattle industry, in which he directed a multi-disciplinary approach to investigate, develop and disseminate science and technology to improve commercial cattle productivity.

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Hand-drawn elevations of proposed residence.

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Hand-drawn plan of proposed residence.

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Current debates about educational theory are concerned with the relationship between knowledge and power and thereby issues such as who possesses a truth and how have they arrived at it, what questions are important to ask, and how should they best be answered. As such, these debates revolve around questions of preferred, appropriate, and useful theoretical perspectives. This paper overviews the key theoretical perspectives that are currently used in physical education pedagogy research and considers how these inform the questions we ask and shapes the conduct of research. It also addresses what is contested with respect to these perspectives. The paper concludes with some cautions about allegiances to and use of theories in line with concerns for the applicability of educational research to pressing social issues.

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One of the challenges in scientific visualization is to generate software libraries suitable for the large-scale data emerging from tera-scale simulations and instruments. We describe the efforts currently under way at SDSC and NPACI to address these challenges. The scope of the SDSC project spans data handling, graphics, visualization, and scientific application domains. Components of the research focus on the following areas: intelligent data storage, layout and handling, using an associated “Floor-Plan” (meta data); performance optimization on parallel architectures; extension of SDSC’s scalable, parallel, direct volume renderer to allow perspective viewing; and interactive rendering of fractional images (“imagelets”), which facilitates the examination of large datasets. These concepts are coordinated within a data-visualization pipeline, which operates on component data blocks sized to fit within the available computing resources. A key feature of the scheme is that the meta data, which tag the data blocks, can be propagated and applied consistently. This is possible at the disk level, in distributing the computations across parallel processors; in “imagelet” composition; and in feature tagging. The work reflects the emerging challenges and opportunities presented by the ongoing progress in high-performance computing (HPC) and the deployment of the data, computational, and visualization Grids.

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Analysis of the structure of the urochordate Herdmania curvata ribosomal DNA intergenic spacer (IGS) and its role in transcription initiation and termination suggests that rRNA gene regulation in this chordate differs from that in vertebrates. A cloned H, curvata IGS is 1881 bp and composed predominantly of two classes of similar repeat sequences that largely alternate in a tandem array. Southern blot hybridization demonstrates that the IGS length variation within an individual and population is largely the result of changes in internal repeat number. Nuclease S1 mapping and primer extension analyses suggest that there are two transcription initiation sites at the 3' end of the most 3' repetitive element; these sites are 6 nucleotides apart. Unlike mouse, Xenopus, and Drosophila, there is no evidence of transcription starting elsewhere in the IGS. Most sequence differences between the promoter repeat and the other internal repeats are in the vicinity of the putative initiation sites. As in Drosophila, nuclease S1 mapping of transcription termination sites suggest that there is not a definitive stop site and a majority of the pre-rRNAs read through a substantial portion of the IGS. Some transcription appears to proceed completely through the promoter repeat into the adjacent rDNA unit. Analysis of oocyte RNA by reverse transcription-polymerase chain reaction (RT-PCR) confirms that readthrough transcription into the adjacent rDNA unit is occurring in some small IGS length variants; there is no evidence of complete readthrough of IGSs larger than 1.0 kb.

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A 1369 bp DNA fragment (Sc) was isolated from a full-length clone of sugarcane bacilliform badnavirus (ScBV) and was shown to have promoter activity in transient expression assays using monocot (banana, maize, millet and sorghum) and dicot plant species (tobacco, sunflower, canola and Nicotiana benthamiana). This promoter was also tested for stable expression in transgenic banana and tobacco plants. These experiments showed that this promoter could drive high-level expression of the beta-glucuronidase (GUS) reporter gene in most plant cells. The expression level was comparable to the maize ubiquitin promoter in standardised transient assays in maize. In transgenic banana plants the expression levels were variable for different transgenic lines but was generally comparable with the activities of both the maize ubiquitin promoter and the enhanced cauliflower mosaic virus (CaMV) 35S promoter. The Sc promoter appears to express in a near-constitutive manner in transgenic banana and tobacco plants. The promoter from sugarcane bacilliform virus represents a useful tool for the high-level expression of foreign genes in both monocot and dicot transgenic plants that could be used similarly to the CaMV 35S or maize polyubiquitin promoter.

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OBJECTIVE: This study ascertains the relative contributions of genetics and environment in determining methane emission in humans and rats. There is considerable interest in the factors determining the microbial species that inhabit the colon. Methanogens, which are archaebacteria, are an easily detected colonic luminal bacteria because they respire methane. They are present in some but not all human colons and lower animal hindguts. Opinion varies on the nature of the factors influencing this ecology with some studies proposing the existence of host genetic influences. METHODS: Methane emission was measured in human twin pairs by gas chromatography, and structural equation modeling was used to determine the proportion of genetic and environmental determinants. The importance of the timing of environmental effects and rat strain on the trait of methane emission were ascertained by experiments with cohabiting methanogenic and nonmethanogenic rats. RESULTS: Analysis of breath samples from 274 adolescent twin pairs and their families indicated that the major influences on the trait of methane emission are the result of shared (53%, 95% confidence interval 39-61) and unique environmental (47%, 95% confidence interval 38-56) effects. No significant autosomal genetic effects were detected, but as observed in other studies, men (37%) were less likely to excrete methane in their breath than women (63%). Investigation of methane emission in rats indicated that environmental effects in this animal are most potent during the weaning period, with stable gut microbial ecology thereafter for some but not all rat strains. CONCLUSIONS: These results are consistent with shared and unique environmental factors being the main determinants of the ecology of this colonic microbe. (Am J Gastroenterol 2000;95:2872-2879. (C) 2000 by Am. Coll. of Gastroenterology).

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Two small RNAs regulate the timing of Caenorhabditis elegans development(1,2). Transition from the first to the second larval stage fates requires the 22-nucleotide lin-4 RNA(1,3,4), and transition from late larval to adult cell fates requires the 21-nucleotide let-7 RNA 2. The lin-4 and let-7 RNA genes are not homologous to each other, but are each complementary to sequences in the 3' untranslated regions of a set of protein-coding target genes that are normally negatively regulated by the RNAs1,2,5,6. Here we have detected let-7 RNAs of similar to 21 nucleotides in samples from a wide range of animal species, including vertebrate, ascidian, hemichordate, mollusc, annelid and arthropod, but not in RNAs from several cnidarian and poriferan species, Saccharomyces cerevisiae, Escherichia coli or Arabidopsis. We did not detect lin-4 RNA in these species. We found that let-7 temporal regulation is also conserved: let-7 RNA expression is first detected at late larval stages in C. elegans and Drosophila, at 48 hours after fertilization in zebrafish, and in adult stages of annelids and molluscs. The let-7 regulatory RNA may control late temporal transitions during development across animal phylogeny.