2,327 research outputs found

    First Observation of Diboson Production in Hadronic Final State at the Tevatron

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    We present the first observation in hadronic collisions of the electroweak production of vector boson pairs (VV; V = W,Z) where one boson decays to a hadronic final state. The data correspond to 3.5/fb of integrated luminosity collected by the CDF II detector in p-pbar collisions at a center-of-mass energy of 1.96 TeV. Event selection requires two identified jets and large transverse momentum imbalance. The analysis employs several novel techniques to suppress multijet background and reduce systematic uncertainties. We observe 1516 +/- 239(stat) +/- 144(syst) diboson candidate events and measure a cross section of sigma(ppbar to VV+X) = 18.0 +/- 2.8(stat) +/- 2.4(syst) +/- 1.1(lumi) pb, in agreement with standard model expectations.Comment: To be published in the proceedings of DPF-2009, Detroit, MI, July 2009, eConf C090726 (6 pages, 4 figures, 2 tables

    Preemption in Congress

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    Ovarian follicular waves and secretion of follicle-stimulating hormone after administration of GnRH at estrus

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    An experiment was conducted to examine the effects of GnRH on the secretion of FSH, LH, estradiol, and progesterone in serum and changes in ovarian structures. Dairy cows were assigned randomly to receive either 100 μg of GnRH or saline 12 hr after estrus (day 0) was detected. Blood was collected daily to assess changes in serum estradiol and progesterone and every 12 min for 8 hr on days 8 and 15 after estrus to assess concentrations of FSH and LH. Diameter and number of follicles were determined daily by real-time ultrasonography. Two patterns of follicular development were observed. The day of peak diameter of each dominant follicle (three or four per cycle) was synchronous with increases in estradiol in serum. The dominant follicle grew at a faster rate in all GnRH-treated cows. We concluded that administering GnRH at estrus increased the pulse frequency of FSH on days 8 and 15 of the cycle, altered follicular dynamics of dominant follicles of the subsequent estrous cycle, and tended to increase concentrations of progesterone in serum of cows

    Efficient Universal Noiseless Source Codes

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    Although the existence of universal noiseless variable-rate codes for the class of discrete stationary ergodic sources has previously been established, very few practical universal encoding methods are available. Efficient implementable universal source coding techniques are discussed in this paper. Results are presented on source codes for which a small value of the maximum redundancy is achieved with a relatively short block length. A constructive proof of the existence of universal noiseless codes for discrete stationary sources is first presented. The proof is shown to provide a method for obtaining efficient universal noiseless variable-rate codes for various classes of sources. For memoryless sources, upper and lower bounds are obtained for the minimax redundancy as a function of the block length of the code. Several techniques for constructing universal noiseless source codes for memoryless sources are presented and their redundancies are compared with the bounds. Consideration is given to possible applications to data compression for certain nonstationary sources
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