480 research outputs found

    Grain Drill Calibration Procedures for Winter Wheat

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    Intensive wheat management requires attention to details, from planting through harvest. Perhaps most critical is stand establishment. While no-tilling wheat into corn stubble presents a range of problems in depth control and residue management, these problems do not minimize the importance of calibration. Just as no two drills are manufactured alike, seed rarely is produced in uniform size, nor do individual metering cups deliver the same seed quantities. A few hours of attention to calibration at the start of fall planting will help producers control seed costs and achieve more desirable, uniform stands and better yields

    Structural and functional properties of genes involved in human cancer

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    BACKGROUND: One of the main goals of cancer genetics is to identify the causative elements at the molecular level leading to cancer. RESULTS: We have conducted an analysis of a set of genes known to be involved in cancer in order to unveil their unique features that can assist towards the identification of new candidate cancer genes. CONCLUSION: We have detected key patterns in this group of genes in terms of the molecular function or the biological process in which they are involved as well as sequence properties. Based on these features we have developed an accurate Bayesian classification model with which human genes have been scored for their likelihood of involvement in cancer

    Fast Evaluation of Feynman Diagrams

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    We develop a new representation for the integrals associated with Feynman diagrams. This leads directly to a novel method for the numerical evaluation of these integrals, which avoids the use of Monte Carlo techniques. Our approach is based on based on the theory of generalized sinc (sin(x)/x\sin(x)/x) functions, from which we derive an approximation to the propagator that is expressed as an infinite sum. When the propagators in the Feynman integrals are replaced with the approximate form all integrals over internal momenta and vertices are converted into Gaussians, which can be evaluated analytically. Performing the Gaussians yields a multi-dimensional infinite sum which approximates the corresponding Feynman integral. The difference between the exact result and this approximation is set by an adjustable parameter, and can be made arbitrarily small. We discuss the extraction of regularization independent quantities and demonstrate, both in theory and practice, that these sums can be evaluated quickly, even for third or fourth order diagrams. Lastly, we survey strategies for numerically evaluating the multi-dimensional sums. We illustrate the method with specific examples, including the the second order sunset diagram from quartic scalar field theory, and several higher-order diagrams. In this initial paper we focus upon scalar field theories in Euclidean spacetime, but expect that this approach can be generalized to fields with spin.Comment: uses feynmp macros; v2 contains improved description of renormalization, plus other minor change

    Detecting microRNA activity from gene expression data

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    <p>Abstract</p> <p>Background</p> <p>MicroRNAs (miRNAs) are non-coding RNAs that regulate gene expression by binding to the messenger RNA (mRNA) of protein coding genes. They control gene expression by either inhibiting translation or inducing mRNA degradation. A number of computational techniques have been developed to identify the targets of miRNAs. In this study we used predicted miRNA-gene interactions to analyse mRNA gene expression microarray data to predict miRNAs associated with particular diseases or conditions.</p> <p>Results</p> <p>Here we combine correspondence analysis, between group analysis and co-inertia analysis (CIA) to determine which miRNAs are associated with differences in gene expression levels in microarray data sets. Using a database of miRNA target predictions from TargetScan, TargetScanS, PicTar4way PicTar5way, and miRanda and combining these data with gene expression levels from sets of microarrays, this method produces a ranked list of miRNAs associated with a specified split in samples. We applied this to three different microarray datasets, a papillary thyroid carcinoma dataset, an in-house dataset of lipopolysaccharide treated mouse macrophages, and a multi-tissue dataset. In each case we were able to identified miRNAs of biological importance.</p> <p>Conclusions</p> <p>We describe a technique to integrate gene expression data and miRNA target predictions from multiple sources.</p

    Corn Stover Availability and Collection Efficiency Using Typical Hay Equipment

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    Corn stover has been identified as a potential feedstock for the production of fermentable sugars and thermochemical processes. The availability and efficiency of typical hay equipment for collecting corn stover has not been well quantified. Corn stover was collected for two years on a central Kentucky farm near Louisville. Six different harvesting treatments, using traditional hay equipment, were used to harvest corn stover. A rotary mower, rotary scythe (flail-type mower with windrow-forming shields), parallel bar rake, and a round baler were utilized. The average stover moisture content prior to grain harvest was above 40%, and field drying was required before baling. All treatments were analyzed for collection efficiency and corn stover yield. The stover collection yields varied from 1.93 to 5.34 dry t/ha, with collection efficiencies (ratio of stover collected to the total above-ground stover excluding grain) between 32.1% and 94.5%. The most promising collection strategy was disengaging the straw chopper and spreader to produce a windrow behind the combine. This windrow could then be baled in a separate operation that resulted in a collection efficiency of 74.1%

    Spatial variation in spring arrival patterns of Afro‐Palaearctic bird migration across Europe

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    Aim: Geographical patterns of migrant species arrival have been little studied, despite their relevance to global change responses. Here, we quantify continent-wide inter-specific variation in spatio-temporal patterns of spring arrival of 30 common migrant bird species and relate these to species characteristics and environmental conditions.Location: EuropeTime period: 2010-2019Major taxa studied: Birds, 30 speciesMethods: Using citizen science data from EuroBirdPortal, we modelled arrival phenology for 30 Afro-Palearctic migrant species across Europe to extract start and duration of species arrival at a 400 km square resolution. We related inter and intra-specific variation in arrival and duration to species characteristics and temperature at the start of the growing season (green-up) .Results: Spatial variation in start of arrival times indicates it took on average 1.6 days for the leading migratory front to move northwards by 100 km (range: 0.6—2.5 days). There was a major gradient in arrival phenology, from species which arrived earlier, least synchronously, in colder temperatures and progressed slowly northwards to species which arrived later, most synchronously and in warmer temperatures, and advanced quickly through Europe. The slow progress of early arrivers suggests that temperature limits their northward advance; this group included Aerial Insectivores and species wintering north of the Sahel. For the late arrivers, which included species wintering further south, seasonal resource availability in Africa may delay their arrival into Europe.Main conclusions: We found support for the green-wave hypothesis applying widely to migratory landbirds. Species arrival phenologies are linked to ecological differences between taxa, such as diet, and wintering location. Understanding these differences informs predictions of species’ sensitivity to global change. Publishing these arrival phenologies will facilitate further research and have additional conservation benefits such as informing designation of hunting seasons. Our methods are applicable to any taxa with repeated occurrence data across large scales. Key words: phenology, European-African migrants, bird migration, spring arrival, spatial variation, intraspecific and interspecific variation, EuroBirdPortal, citizen scientists, complete lists and casual record

    Thermal sensitivity of feeding and burrowing activity of an invasive crayfish in UK waters

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    Climate change and invasive species are among the biggest threats to global biodiversity and ecosystem function. Although the individual impacts of climate change and invasive species are commonly assessed, we know far less about how a changing climate may impact invading species. Increases in water temperature due to climate change are likely to alter the thermal regime of UK rivers, and this in turn may influence the performance of invasive species such as signal crayfish (Pacifastacus leniusculus), which are known to have deleterious impacts on native ecosystems. We evaluate the relationship between water temperature and two key performance traits in signal crayfish—feeding and burrowing rate—using thermal experiments on wild‐caught individuals in a laboratory environment. Although water temperature was found to have no significant influence on burrowing rate, it did have a strong effect on feeding rate. Using the thermal performance curve for feeding rate, we evaluate how the thermal suitability of three UK rivers for signal crayfish may change as a result of future warming. We find that warming rivers may increase the amount of time that signal crayfish can achieve high feeding rate levels. These results suggest that elevated river water temperatures as a result of climate change may promote higher signal crayfish performance in the future, further exacerbating the ecological impact of this invasive species

    Towards Structure-Property-Function Relationships for Eumelanin

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    We discuss recent progress towards the establishment of important structure-property-function relationships in eumelanins - key functional bio-macromolecular systems responsible for photo-protection and immune response in humans, and implicated in the development of melanoma skin cancer. We focus on the link between eumelanin's secondary structure and optical properties such as broad band UV-visible absorption and strong non-radiative relaxation; both key features of the photo-protective function. We emphasise the insights gained through a holistic approach combining optical spectroscopy with first principles quantum chemical calculations, and advance the hypothesis that the robust functionality characteristic of eumelanin is related to extreme chemical and structural disorder at the secondary level. This inherent disorder is a low cost natural resource, and it is interesting to speculate as to whether it may play a role in other functional bio-macromolecular systems.Comment: 19 pages, 8 figures, Invited highlight article for Soft Matte

    GWIPS-viz: development of a ribo-seq genome browser

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    We describe the development of GWIPS-viz (http://gwips.ucc.ie), an online genome browser for viewing ribosome profiling data. Ribosome profiling (ribo-seq) is a recently developed technique that provides genome-wide information on protein synthesis (GWIPS) in vivo. It is based on the deep sequencing of ribosome-protected messenger RNA (mRNA) fragments, which allows the ribosome density along all mRNA transcripts present in the cell to be quantified. Since its inception, ribo-seq has been carried out in a number of eukaryotic and prokaryotic organisms. Owing to the increasing interest in ribo-seq, there is a pertinent demand for a dedicated ribo-seq genome browser. GWIPS-viz is based on The University of California Santa Cruz (UCSC) Genome Browser. Ribo-seq tracks, coupled with mRNA-seq tracks, are currently available for several genomes: human, mouse, zebrafish, nematode, yeast, bacteria (Escherichia coli K12, Bacillus subtilis), human cytomegalovirus and bacteriophage lambda. Our objective is to continue incorporating published ribo-seq data sets so that the wider community can readily view ribosome profiling information from multiple studies without the need to carry out computational processing
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