4,211 research outputs found

    Analysis of atmospheric spectra for trace gases

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    The objective is the comprehensive analysis of high resolution atmospheric spectra recorded in the middle-infrared region to obtain simultaneous measurements of coupled parameters (gas concentrations of key trace constituents, total column amounts, pressure, and temperature) in the stratosphere and upper troposphere. Solar absorption spectra recorded at 0.002 and 0.02 cm exp -1 resolutions with the University of Denver group's balloon-borne, aircraft borne, and ground-based interferometers and 0.005 to 0.01 cm exp -1 resolution solar spectra from Kitt Peak are used in the analyses

    Microbiome profiling by Illumina sequencing of combinatorial sequence-tagged PCR products

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    We developed a low-cost, high-throughput microbiome profiling method that uses combinatorial sequence tags attached to PCR primers that amplify the rRNA V6 region. Amplified PCR products are sequenced using an Illumina paired-end protocol to generate millions of overlapping reads. Combinatorial sequence tagging can be used to examine hundreds of samples with far fewer primers than is required when sequence tags are incorporated at only a single end. The number of reads generated permitted saturating or near-saturating analysis of samples of the vaginal microbiome. The large number of reads al- lowed an in-depth analysis of errors, and we found that PCR-induced errors composed the vast majority of non-organism derived species variants, an ob- servation that has significant implications for sequence clustering of similar high-throughput data. We show that the short reads are sufficient to assign organisms to the genus or species level in most cases. We suggest that this method will be useful for the deep sequencing of any short nucleotide region that is taxonomically informative; these include the V3, V5 regions of the bac- terial 16S rRNA genes and the eukaryotic V9 region that is gaining popularity for sampling protist diversity.Comment: 28 pages, 13 figure

    The effects of dietary mineral regimen on starter pig growth performance and blood and immune parameters

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    Two hundred sixty-six weanling pigs (initially 12.461b and 21 d of age) were used in a 34-\u3c1 growth assay to evaluate the effects of various mineral supplementation regimens on starter pig growth, immune status, blood parameters, and liver mineral status.. Pigs were fed either a control diet, 3,000 ppm zinc (Zn) in phase I and 2,000 ppm Zn in phase II and III, 250 ppm copper during the entire trial, or a combination of these three diets. These results support our current recommendations of adding zinc oxide in diets of pigs weighing up to 25 lb and copper sulfate in diets fed to pigs from 25 to 50 lb.; Swine Day, Manhattan, KS, November 16, 199

    Parallel imaging: is GRAPPA a useful acquisition tool for MR imaging intended for volumetric brain analysis?

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    <p>Abstract</p> <p>Background</p> <p>The work presented here investigates parallel imaging applied to T1-weighted high resolution imaging for use in longitudinal volumetric clinical studies involving Alzheimer's disease (AD) and Mild Cognitive Impairment (MCI) patients. This was in an effort to shorten acquisition times to minimise the risk of motion artefacts caused by patient discomfort and disorientation. The principle question is, "Can parallel imaging be used to acquire images at 1.5 T of sufficient quality to allow volumetric analysis of patient brains?"</p> <p>Methods</p> <p>Optimisation studies were performed on a young healthy volunteer and the selected protocol (including the use of two different parallel imaging acceleration factors) was then tested on a cohort of 15 elderly volunteers including MCI and AD patients. In addition to automatic brain segmentation, hippocampus volumes were manually outlined and measured in all patients. The 15 patients were scanned on a second occasion approximately one week later using the same protocol and evaluated in the same manner to test repeatability of measurement using images acquired with the GRAPPA parallel imaging technique applied to the MPRAGE sequence.</p> <p>Results</p> <p>Intraclass correlation tests show that almost perfect agreement between repeated measurements of both segmented brain parenchyma fraction and regional measurement of hippocampi. The protocol is suitable for both global and regional volumetric measurement dementia patients.</p> <p>Conclusion</p> <p>In summary, these results indicate that parallel imaging can be used without detrimental effect to brain tissue segmentation and volumetric measurement and should be considered for both clinical and research studies where longitudinal measurements of brain tissue volumes are of interest.</p

    Evolutionary connectionism: algorithmic principles underlying the evolution of biological organisation in evo-devo, evo-eco and evolutionary transitions

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    The mechanisms of variation, selection and inheritance, on which evolution by natural selection depends, are not fixed over evolutionary time. Current evolutionary biology is increasingly focussed on understanding how the evolution of developmental organisations modifies the distribution of phenotypic variation, the evolution of ecological relationships modifies the selective environment, and the evolution of reproductive relationships modifies the heritability of the evolutionary unit. The major transitions in evolution, in particular, involve radical changes in developmental, ecological and reproductive organisations that instantiate variation, selection and inheritance at a higher level of biological organisation. However, current evolutionary theory is poorly equipped to describe how these organisations change over evolutionary time and especially how that results in adaptive complexes at successive scales of organisation (the key problem is that evolution is self-referential, i.e. the products of evolution change the parameters of the evolutionary process). Here we first reinterpret the central open questions in these domains from a perspective that emphasises the common underlying themes. We then synthesise the findings from a developing body of work that is building a new theoretical approach to these questions by converting well-understood theory and results from models of cognitive learning. Specifically, connectionist models of memory and learning demonstrate how simple incremental mechanisms, adjusting the relationships between individually-simple components, can produce organisations that exhibit complex system-level behaviours and improve the adaptive capabilities of the system. We use the term “evolutionary connectionism” to recognise that, by functionally equivalent processes, natural selection acting on the relationships within and between evolutionary entities can result in organisations that produce complex system-level behaviours in evolutionary systems and modify the adaptive capabilities of natural selection over time. We review the evidence supporting the functional equivalences between the domains of learning and of evolution, and discuss the potential for this to resolve conceptual problems in our understanding of the evolution of developmental, ecological and reproductive organisations and, in particular, the major evolutionary transitions

    The First HET Planet: A Companion to HD 37605

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    We report the first detection of a planetary-mass companion to a star using the High Resolution Spectrograph (HRS) of the Hobby-Eberly Telescope (HET). The HET-HRS now gives routine radial velocity precision of 2-3 m/s for high SNR observations of quiescent stars. The planetary-mass companion to the metal-rich K0V star HD37605 has an orbital period of 54.23 days, an orbital eccentricity of 0.737, and a minimum mass of 2.84 Jupiter masses. The queue-scheduled operation of the Hobby-Eberly Telescope enabled us to discovery of this relatively short-period planet with a total observation time span of just two orbital periods. The ability of queue-scheduled large-aperture telescopes to respond quickly to interesting and important results demonstrates the power of this new approach in searching for extra-solar planets as well as in other ares of research requiring rapid response time critical observations.Comment: 4 Pages, 2 figures. Accepted in Astrophysical Journal Letters, http://austral.as.utexas.edu/planets/hd37605/hd37605.htm

    Evaluating major curriculum change:the effect on student confidence

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    Aim: The aim of this study was to evaluate the effect of major curriculum change within a UK dental school on final-year student self-rated confidence levels. Methods: Final-year dental students graduating in each year between 2007 and 2012 completed the same course evaluation questionnaire, which assessed their confidence in relation to a range of clinical procedures using a Likert-type scale. This period spanned the introduction of a new curriculum and allowed analysis of differences in self-rated confidence between students graduating from the old (2007 and 2008) and new (2009–2012) curricula, across thirty key procedures. Results: New curriculum students showed significantly higher self-confidence ratings in nineteen of the thirty procedures, compared with those on the old curriculum. For the remaining eleven procedures there was no significant difference between the two curricula. The proportion of students on the outcomes-based curriculum rating themselves as 'confident” was statistically significantly higher in seven out of the thirty procedures, when compared with the traditional curriculum, and unchanged or nonsignificantly increased in the remainder. Discussion and conclusions: The relationship between specific curricular innovations and student confidence is considered, as is the usefulness of self-rated confidence in curriculum evaluation. Curriculum change appeared to have a positive effect on student confidence across a range of procedures
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