10,242 research outputs found
A high performance scanning force microscope head design
A stable and highly sensitive scanning force microscope head design is presented. The head provides an implementation of the optical lever detection method in which mechanical vibration noise has been minimized
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Data on mountain environments: III. Front Range, Colorado, four climax regions, 1959-1964
The effect of genomic information on optimal contribution selection in livestock breeding programs
BACKGROUND: Long-term benefits in animal breeding programs require that increases in genetic merit be balanced with the need to maintain diversity (lost due to inbreeding). This can be achieved by using optimal contribution selection. The availability of high-density DNA marker information enables the incorporation of genomic data into optimal contribution selection but this raises the question about how this information affects the balance between genetic merit and diversity. METHODS: The effect of using genomic information in optimal contribution selection was examined based on simulated and real data on dairy bulls. We compared the genetic merit of selected animals at various levels of co-ancestry restrictions when using estimated breeding values based on parent average, genomic or progeny test information. Furthermore, we estimated the proportion of variation in estimated breeding values that is due to within-family differences. RESULTS: Optimal selection on genomic estimated breeding values increased genetic gain. Genetic merit was further increased using genomic rather than pedigree-based measures of co-ancestry under an inbreeding restriction policy. Using genomic instead of pedigree relationships to restrict inbreeding had a significant effect only when the population consisted of many large full-sib families; with a half-sib family structure, no difference was observed. In real data from dairy bulls, optimal contribution selection based on genomic estimated breeding values allowed for additional improvements in genetic merit at low to moderate inbreeding levels. Genomic estimated breeding values were more accurate and showed more within-family variation than parent average breeding values; for genomic estimated breeding values, 30 to 40% of the variation was due to within-family differences. Finally, there was no difference between constraining inbreeding via pedigree or genomic relationships in the real data. CONCLUSIONS: The use of genomic estimated breeding values increased genetic gain in optimal contribution selection. Genomic estimated breeding values were more accurate and showed more within-family variation, which led to higher genetic gains for the same restriction on inbreeding. Using genomic relationships to restrict inbreeding provided no additional gain, except in the case of very large full-sib families
Heat transfer and pressure drop data for high heat flux densities to water at high subcritical pressures
Local surface ooeffioients of heat t-ansfer, overall pressure drop data and mean friction factor are presented for heat flamms up to 3.52106 BtuAr ft2 for water flowing in a nickel tabe isder the following conditions: mass rates of flow up to 5.6x 106 lb.m/hr ft2 (or inlet velocities up to 30 ft/sec), absolute pressures up to 2000 pula, and liquid suboooling between 50 F and 250 T. The test section dmnsins were 0.160 inoh I.D. and 9.4 inches long.Office of Naval Researc
Persistent Topology of Syntax
We study the persistent homology of the data set of syntactic parameters of
the world languages. We show that, while homology generators behave erratically
over the whole data set, non-trivial persistent homology appears when one
restricts to specific language families. Different families exhibit different
persistent homology. We focus on the cases of the Indo-European and the
Niger-Congo families, for which we compare persistent homology over different
cluster filtering values. We investigate the possible significance, in
historical linguistic terms, of the presence of persistent generators of the
first homology. In particular, we show that the persistent first homology
generator we find in the Indo-European family is not due (as one might guess)
to the Anglo-Norman bridge in the Indo-European phylogenetic network, but is
related to the position of Ancient Greek and the Hellenic branch within the
network.Comment: 15 pages, 25 jpg figure
Bidding Behavior in Virtual versus Live Auctions: An Examination of the eBay Collectibles Market
Over the last few years many consumer-related virtual auction sites have sprung up on the web. One of the most successful of these is eBay. Single item auctions on this site share characteristics with both English and a hybrid combination of first-price and second-price sealed bid auctions. This paper describes research in progress to determine the effects of the specific structure of eBay auctions on bidding strategies while drawing on traditional auction theory which was devised by examining live auctions not mediated by computers. The results of the study should have implications for bidders, sellers, and managers of auction web sites
Bidder Experience In Online Auctions: Effects On Bidding Choices And Revenue
This paper describes research to determine the effects of bidder experience on performance in online auctions. Choice of bid type, the timing of bids, and the price paid are all examined for very experienced and very inexperienced bidders. The study draws on information systems empirical research, traditional auction theory, the results of lab experiments involving "live" auctions not mediated by computers, and existing research on online auctions. The results indicate that bidder experience is related to timing of bids and choice of bid type, but not to revenue realized. These findings have implications for bidders and researchers
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