81 research outputs found

    Increasing Transit Ridership: Lessons from the Most Successful Transit Systems in the 1990s, MTI Report-01-22

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    This study systematically examines recent trends in public transit ridership in the U.S. during the 1990s. Specifically, this analysis focuses on agencies that increased ridership during the latter half of the decade. While transit ridership increased steadily by 13 percent nationwide between 1995 and 1999, not all systems experienced ridership growth equally. While some agencies increased ridership dramatically, some did so only minimally, and still others lost riders. What sets these agencies apart from each other? What explains the uneven growth in ridership

    Loss of vtx Genes after the First Subcultivation Step of Verocytotoxigenic Escherichia coli O157 and Non-O157 during Isolation from Naturally Contaminated Fecal Samples

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    Verocytotoxins VT1 and VT2,produced by Verocytotoxigenic Escherichia coli (VTEC), are encoded on temperate bacteriophages. Several studies reported the loss of the vtx genes after multiple subcultivation steps or long preservation. The objective of this study was to determine if the loss of the verocytotoxin genes can already occur during the first subcultivation step. Consequently, the stability of the vtx genes were tested in 40 isolates originating from 40 vtx-positive fecal samples after the first subcultivation step following the isolation procedure. The loss occurred in 12 out of 40 strains tested and was rather rare among the O157 strains compared to the non-O157 strains. This is the first study demonstrating that the loss of the verocytotoxin genes can already occur after the first subcultivation step. This may lead to an underestimation of VTEC positive samples

    Observation of the Decay B=> J/psi eta K and Search for X(3872)=> J/psi eta

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    We report the observation of the BB meson decay B±J/ψηK±B^\pm\to J/\psi \eta K^\pm and evidence for the decay B0J/ψηKS0B^0\to J/\psi \eta K^0_S, using {90} million BBbarBBbar events collected at the \ensuremath{\Upsilon{(4S)}}\xspace resonance with the BaBarBaBar detector at the PEP-II e+ee^+ e^- asymmetric-energy storage ring. We obtain branching fractions of B\cal{B}(B±J/ψηK±(B^\pm\to J/\psi \eta K^{\pm})=(10.8±2.3(stat.)±2.4(syst.))×105(10.8\pm 2.3(\rm{stat.})\pm 2.4(\rm{syst.}))\times 10^{-5} and B\cal{B}(B0J/ψηKS0(B^0\to J/\psi\eta K_{\rm{S}}^{0})=(8.4±2.6(stat.)±2.7(syst.))×105(8.4\pm 2.6(\rm{stat.})\pm 2.7(\rm{syst.}))\times 10^{-5}. We search for the new narrow mass state, the X(3872), recently reported by the Belle Collaboration, in the decay B^\pm\to X(3872)K^\pm, X(3872)\to \jpsi \eta and determine an upper limit of B\cal{B}(B^\pm \to X(3872) K^\pm \to \jpsi \eta K^\pm) <7.7×106<7.7\times 10^{-6} at 90% C.L.Comment: 7 pages and two figures, submitted to Phys. Rev. Lett

    Measurement of the Ratio of b Quark Production Cross Sections in Antiproton-Proton Collisions at 630 GeV and 1800 GeV

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    We report a measurement of the ratio of the bottom quark production cross section in antiproton-proton collisions at 630 GeV to 1800 GeV using bottom quarks with transverse momenta greater than 10.75 GeV identified through their semileptonic decays and long lifetimes. The measured ratio sigma(630)/sigma(1800) = 0.171 +/- .024 +/- .012 is in good agreement with next-to-leading order (NLO) quantum chromodynamics (QCD)

    Measurement of time-dependent CP asymmetries in B-0 -> D-(*)+/-pi(-/+) decays and constraints on sin(2 beta+gamma)

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    We present a measurement of CP-violating asymmetries in fully reconstructed B-0-->D((*)+/-)pi(-/+) decays in approximately 88x10(6) Y(4S)-->B (B) over bar decays collected with the BABAR detector at the PEP-II asymmetric-energy B factory at SLAC. From a time-dependent maximum-likelihood fit we obtain the following for the CP-violating parameters: a=-0.022+/-0.038 (stat)+/-0.020 (syst), a(*)=-0.068+/-0.038 (stat)+/-0.020 (syst), c(lep)=+0.025+/-0.068 (stat)+/-0.033 (syst), and c(lep)(*)=+0.031+/-0.070 (stat)+/-0.033 (syst). Using other measurements and theoretical assumptions we interpret the results in terms of the angles of the Cabibbo-Kobayashi-Maskawa unitarity triangle, and find parallel tosin(2beta+gamma)parallel to>0.69 at 68% confidence level. We exclude the hypothesis of no CP violation [sin(2beta+gamma)=0] at 83% confidence level

    Search for the rare decay B-0 ->tau(+)tau(-) at BABAR

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    We present the results of a search for the decay B-0 ->tau(+)tau(-) in a data sample of (232 +/- 3)x10(6) Upsilon(4S)-> BB decays using the BABAR detector. Certain extensions of the standard model predict measurable levels of this otherwise rare decay. We reconstruct fully one neutral B meson and seek evidence for the signal decay in the rest of the event. We find no evidence for signal events and obtain B(B-0 ->tau(+)tau(-))< 4.1x10(-3) at the 90% confidence level
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