1,056 research outputs found
A novel, high-sensitivity, bacteriophage-based assay identifies low level Mycobacterium tuberculosis bacteraemia in immunocompetent patients with active and incipient tuberculosis
Haematogenous dissemination of M. tuberculosis (Mtb) is critical to pathogenesis of progressive tuberculous infection in animal models. Using a novel phage-based blood assay, we report the first concordant evidence in well-characterised immunocompetent human cohorts, demonstrating associations of Mtb bacteraemia with progressive phenotypes of latent infection and active pulmonary TB respectively
Design of Modular, Shape-transitioning Inlets for a Conical Hypersonic Vehicle
For a hypersonic vehicle, propelled by scramjet engines, integration of the engines and airframe is highly desirable. Thus, the forward capture shape of the engine inlet should conform to the vehicle body shape. Furthermore, the use of modular engines places a constraint on the shape of the inlet sidewalls. Finally, one may desire a combustor cross- section shape that is different from that of the inlet. These shape constraints for the inlet can be accommodated by employing a streamline-tracing and lofting technique. This design technique was developed by Smart for inlets with a rectangular-to-elliptical shape transition. In this paper, we generalise that technique to produce inlets that conform to arbitrary shape requirements. As an example, we show the design of a body-integrated hypersonic inlet on a winged-cone vehicle, typical of what might be used in a three-stage orbital launch system. The special challenge of inlet design for this conical vehicle at an angle-of-attack is also discussed. That challenge is that the bow shock sits relatively close to the vehicle body
pp elastic scattering for incident momenta between 1.0 and 2.50 BeV/c
This is a report on a measurement of pp elastic scattering for 30° ≤ 0 c.m. ≤ 90° and for incident momenta between 1.0 and 2.50 BeV/c. In the past rather extensive counter measurements(1) of this cross section have been made at high energies and low momentum transfers, but little counter data exist at large momentum transfer. The hydrogen bubble chambers(2,3) have produced data between 3.0 and 4.0 BeV/c, but the number of events at large momentum transfer is limited and the statistical accuracy is poor
Measurement of the eta-Meson Mass using psi(2S) --> eta J/psi
We measure the mass of the eta meson using psi(2S) --> eta J/psi events
acquired with the CLEO-c detector operating at the CESR e+e- collider. Using
the four decay modes eta --> gamma gamma, 3pi0, pi+pi-pi0, and pi+pi-gamma, we
find M(eta)=547.785 +- 0.017 +- 0.057 MeV, in which the first uncertainty is
statistical and the second systematic. This result has an uncertainty
comparable to the two most precise previous measurements and is consistent with
that of NA48, but is inconsistent at the level of 6.5sigma with the much
smaller mass obtained by GEM.Comment: 10 pages postscript,also available through
http://www.lns.cornell.edu/public/CLNS/2007/, Submitted to PR
Determination of the D0 -> K+pi- Relative Strong Phase Using Quantum-Correlated Measurements in e+e- -> D0 D0bar at CLEO
We exploit the quantum coherence between pair-produced D0 and D0bar in
psi(3770) decays to study charm mixing, which is characterized by the
parameters x and y, and to make a first determination of the relative strong
phase \delta between doubly Cabibbo-suppressed D0 -> K+pi- and Cabibbo-favored
D0bar -> K+pi-. We analyze a sample of 1.0 million D0D0bar pairs from 281 pb^-1
of e+e- collision data collected with the CLEO-c detector at E_cm = 3.77 GeV.
By combining CLEO-c measurements with branching fraction input and
time-integrated measurements of R_M = (x^2+y^2)/2 and R_{WS} = Gamma(D0 ->
K+pi-)/Gamma(D0bar -> K+pi-) from other experiments, we find \cos\delta = 1.03
+0.31-0.17 +- 0.06, where the uncertainties are statistical and systematic,
respectively. In addition, by further including external measurements of charm
mixing parameters, we obtain an alternate measurement of \cos\delta = 1.10 +-
0.35 +- 0.07, as well as x\sin\delta = (4.4 +2.7-1.8 +- 2.9) x 10^-3 and \delta
= 22 +11-12 +9-11 degrees.Comment: 37 pages, also available through
http://www.lns.cornell.edu/public/CLNS/2007/. Incorporated referee's comment
Suppressed Decays of D_s^+ Mesons to Two Pseudoscalar Mesons
Using data collected near the Ds*+ Ds- peak production energy Ecm = 4170 MeV
by the CLEO-c detector, we study the decays of Ds+ mesons to two pseudoscalar
mesons. We report on searches for the singly-Cabibbo-suppressed Ds+ decay modes
K+ eta, K+ eta', pi+ K0S, K+ pi0, and the isospin-forbidden decay mode Ds+ to
pi+ pi0. We normalize with respect to the Cabibbo-favored Ds+ modes pi+ eta,
pi+ eta', and K+ K0S, and obtain ratios of branching fractions: Ds+ to K+ eta /
Ds+ to pi+ eta = (8.9 +- 1.5 +- 0.4)%, Ds+ to K+ eta' / Ds+ to pi+ eta' = (4.2
+- 1.3 +- 0.3)%, Ds+ to pi+ K0S / Ds+ to K+ K0S = (8.2 +- 0.9 +- 0.2)%, Ds+ to
K+ pi0 / Ds+ to K+ K0S = (5.0 +- 1.2 +- 0.6)%, and Ds+ to pi+ pi0 / Ds+ to K+
K0S < 4.1% at 90% CL, where the uncertainties are statistical and systematic,
respectively.Comment: 9 pages postscript,also available through
http://www.lns.cornell.edu/public/CLNS/2007/, Submitted to PR
Measurement of the Decay Constant using $D_S^+ --> ell^+ nu
We measure the decay constant fDs using the Ds -> l+ nu channel, where the l+
designates either a mu+ or a tau+, when the tau+ -> pi+ nu. Using both
measurements we find fDs = 274 +-13 +- 7 MeV. Combining with our previous
determination of fD+, we compute the ratio fDs/fD+ = 1.23 +- 0.11 +- 0.04. We
compare with theoretical estimates.Comment: 6 pages postscript,also available through
http://www.lns.cornell.edu/public/CLNS/2007
Measurement of Absolute Hadronic Branching Fractions of D Mesons and e^+ e^- --> D D-bar Cross Sections at the psi(3770)
Using 281 /pb of e^+ e^- collisions recorded at the psi(3770) resonance with
the CLEO-c detector at CESR, we determine absolute hadronic branching fractions
of charged and neutral D mesons using a double tag technique. Among
measurements for three D^0 and six D^+ modes, we obtain reference branching
fractions B(D^0 --> K^-pi^+) = (3.891 +- 0.035 +- 0.059 +- 0.035)% and B(D^+
--> K^-pi^+pi^+) = (9.14 +- 0.10 +- 0.16 +- 0.07)%, where the first uncertainty
is statistical, the second is all systematic errors other than final state
radiation (FSR), and the third is the systematic uncertainty due to FSR. We
include FSR in these branching fractions by allowing for additional unobserved
photons in the final state. Using an independent determination of the
integrated luminosity, we also extract the cross sections sigma(e+e- --> D^0
D^0-bar) = (3.66+- 0.03 +- 0.06) nb and sigma(e+e- --> D^+ D^-) = (2.91+- 0.03
+- 0.05) nb at a center of mass energy, E_cm = 3774 +- 1 MeV.Comment: 47 pages, postscript also available through this
http://www.lns.cornell.edu/public/CLNS/2007/, to be published in PRD, updated
branching fractions using B(KS0 --> pi+ pi-) from PDG 2007, and updated text
in response to the PRD reviewe
Search for Lepton Flavor Violation in Upsilon Decays
In this Letter we describe a search for lepton flavor violation (LFV) in the
bottomonium system. We search for leptonic decays of Upsilon(nS)(n=1,2, and 3)
into muon and tau using the data collected with the CLEO III detector. We
identify the tau lepton using its leptonic decay into electron and utilize
multidimensional likelihood fitting with PDF shapes measured from independent
data samples. We report our estimates of 95% CL upper limits on LFV branching
fractions of Upsilon mesons. We interpret our results in terms of the exclusion
plot for the energy scale of a hypothetical new interaction versus its
effective LFV coupling in the framework of effective field theory.Comment: 10 pages, 3 figures, available through
http://www.lns.cornell.edu/public/CLNS/, submitted to PR
Observation of the Dalitz Decay
Using 586 of collision data acquired at
GeV with the CLEO-c detector at the Cornell Electron Storage
Ring, we report the first observation of
with a significance of . The ratio of branching fractions
\calB(D_{s}^{*+} \to D_{s}^{+} e^{+} e^{-}) / \calB(D_{s}^{*+} \to D_{s}^{+}
\gamma) is measured to be , which is consistent with theoretical expectations
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