474 research outputs found

    The group of endotrivial modules for the symmetric and alternating groups.

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    We complete a classification of the groups of endotrivial modules for the modular group algebras of symmetric groups and alternating groups. We show that, for n ≥ p2, the torsion subgroup of the group of endotrivial modules for the symmetric groups is generated by the sign representation. The torsion subgroup is trivial for the alternating groups. The torsion-free part of the group is free abelian of rank 1 if n ≥ p2 + p and has rank 2 if p2 ≤ n < p2 + p. This completes the work begun earlier by Carlson, Mazza and Nakano

    History, Geology and Water in the Lower Platte River Valley in Eastern Nebraska

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    Effects of Supplementing High Levels of Cu, Co, Mn, and Zn After Calving on Productivity of Two-Year-Old Cows

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    When cow management, health and nutrition are adequate. supplementation of trace minerals at high levels is not beneficial and may in fact be detrimental to reproductive performance

    Intact Pathway Successfully Buffers Sage Grouse Migration

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    Landscape conservation is the mechanism for conserving migratory wildlife in sagebrush ecosystems. We studied a greater sage grouse (Centrocercus urophasianus; hereafter ‘sage-grouse’) population with the longest-known annual migration, ? 240 km round-trip, between summer and winter ranges in Saskatchewan, Canada, and northcentral Montana. We asked: Do birds fly quickly through a corridor, or do they use stopovers within a larger pathway? GPS-tracking revealed that migrating grouse frequent stopovers along multiple routes that coalesce to form an integrated pathway. Month-long fall migration in November contrasted with punctuated spring migration lasting ~2 weeks in late March/early April. Individual birds typically spent ~1 day at 9 different stopovers, migrating 71-91 km in 11-15 days. Migrating grouse used native sagebrush rangeland in proportion to its availability and avoided cropland and badlands. Birds responded to record-breaking snowfall in winter 2011 (&gt;274 cm) by migrating another ? 50 km south onto windswept ridge tops where sagebrush remained above snow. Grouse selected habitat on Charles M. Russell National Wildlife Refuge most similar to typical winter habitat. Doing so was without consequence to winter survival; such was not the case for a nearby resident population. Newly identified winter range suggests that high site fidelity is tempered by an ability to adapt quickly when resources become scarce. We recommend public land policy that provides grazing opportunities while precluding large-scale energy development or whole scale removal of sagebrush. Management actions that maintain sagebrush as an emergency food source in newly identified sage grouse wintering grounds will help conserve this migratory population

    Principles for the post-GWAS functional characterisation of risk loci

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    Several challenges lie ahead in assigning functionality to susceptibility SNPs. For example, most effect sizes are small relative to effects seen in monogenic diseases, with per allele odds ratios usually ranging from 1.15 to 1.3. It is unclear whether current molecular biology methods have enough resolution to differentiate such small effects. Our objective here is therefore to provide a set of recommendations to optimize the allocation of effort and resources in order maximize the chances of elucidating the functional contribution of specific loci to the disease phenotype. It has been estimated that 88% of currently identified disease-associated SNP are intronic or intergenic. Thus, in this paper we will focus our attention on the analysis of non-coding variants and outline a hierarchical approach for post-GWAS functional studies

    3-D extent of the main ionospheric trough - a case study

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    The EISCAT radar system has been used for the first time in a four-beam meridional mode. The FAST satellite and ALIS imaging system is used in conjunction to support the radar data, which was used to identify a main ionospheric trough. With this large latitude coverage the trough was passed in 21/2hours period. Its 3-dimensional structure is investigated and discussed. It is found that the shape is curved along the auroral oval, and that the trough is wider closer to the midnight sector. The position of the trough coincide rather well with various statistical models and this trough is found to be a typical one

    Construction of a bacterial artificial chromosome library from the spikemoss Selaginella moellendorffii: a new resource for plant comparative genomics

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    BACKGROUND: The lycophytes are an ancient lineage of vascular plants that diverged from the seed plant lineage about 400 Myr ago. Although the lycophytes occupy an important phylogenetic position for understanding the evolution of plants and their genomes, no genomic resources exist for this group of plants. RESULTS: Here we describe the construction of a large-insert bacterial artificial chromosome (BAC) library from the lycophyte Selaginella moellendorffii. Based on cell flow cytometry, this species has the smallest genome size among the different lycophytes tested, including Huperzia lucidula, Diphaiastrum digita, Isoetes engelmanii and S. kraussiana. The arrayed BAC library consists of 9126 clones; the average insert size is estimated to be 122 kb. Inserts of chloroplast origin account for 2.3% of the clones. The BAC library contains an estimated ten genome-equivalents based on DNA hybridizations using five single-copy and two duplicated S. moellendorffii genes as probes. CONCLUSION: The S. moellenforffii BAC library, the first to be constructed from a lycophyte, will be useful to the scientific community as a resource for comparative plant genomics and evolution

    Deciphering the genome structure and paleohistory of _Theobroma cacao_

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    We sequenced and assembled the genome of _Theobroma cacao_, an economically important tropical fruit tree crop that is the source of chocolate. The assembly corresponds to 76% of the estimated genome size and contains almost all previously described genes, with 82% of them anchored on the 10 _T. cacao_ chromosomes. Analysis of this sequence information highlighted specific expansion of some gene families during evolution, for example flavonoid-related genes. It also provides a major source of candidate genes for _T. cacao_ disease resistance and quality improvement. Based on the inferred paleohistory of the T. cacao genome, we propose an evolutionary scenario whereby the ten _T. cacao_ chromosomes were shaped from an ancestor through eleven chromosome fusions. The _T. cacao_ genome can be considered as a simple living relic of higher plant evolution
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