2,779 research outputs found

    Overview of Charm Physics at RHIC

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    Heavy-quark production provides a sensitive probe of the gluon structure of nucleons and its modication in nuclei. It is also a key probe of the hot-dense matter created in heavy-ion collisions. We will discuss the physics issues involved, as seen in quarkonia and open heavy-quark production, starting with those observed in proton-proton collisions. Then cold nuclear matter effects on heavy-quark production including shadowing, gluon saturation, energy loss and absorption will be reviewed in the context of recent proton-nucleus and deuteron-nucleus measurements. Next we survey the most recent measurements of open-charm and J/Psi's in heavy-ion collisions at RHIC and their interpretation. We discuss the high-pT suppression and flow of open charm in terms of energy loss and thermalization and, for J/Psi, contrast explanations in terms of screening in a deconfined medium vs. recombination models.Comment: 6 pages, 12 figures, proceedings for Quark Confinement and Hadron Spectrum VI

    Intravenous conscious sedation in patients under 16 years of age. Fact or fiction?

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    Recently published guidelines on the use of conscious sedation in dentistry have published varying recommendations on the lower age limit for the use of intravenous conscious sedation. There are a large number of dentists currently providing dental treatment for paediatric patients under intravenous conscious sedation. The 18 cases reported here (age range 11-15 years), were successfully managed with intravenous conscious sedation. The experience in this paper is not sufficient evidence to recommend the wholesale use of intravenous conscious sedation in patients who are under 16 years. The fact that a range of operators can use these techniques on paediatric patients would suggest that further study should be carried out in this population. The guidance should be modified to say there is insufficient evidence to support the use of intravenous conscious sedation in children, rather than arbitrarily selecting a cut off point at age 16 years

    Optical Observations of the Binary Millisecond Pulsars J2145-0750 and J0034-0534

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    We report on optical observations of the low-mass binary millisecond pulsar systems J0034-0534 and J2145-0750. A faint (I=23.5) object was found to be coincident with the timing position of PSR J2145-0750. While a galaxy or distant main-sequence star cannot be ruled out, its magnitude is consistent with an ancient white dwarf, as expected from evolutionary models. For PSR J0034-0534 no objects were detected to a limiting magnitude of R=25.0, suggesting that the white dwarf in this system is cold. Using white dwarf cooling models, the limit on the magnitude of the PSR J0034-0534 companion suggests that at birth the pulsar in this system may have rotated with a period as short as 0.6 ms. These observations provide further evidence that the magnetic fields of millisecond pulsars do not decay on time scales shorter than 1 Gyr.Comment: 6 pages, uuencoded, gz -9 compressed postscript, accepted by ApJ

    A Sunyaev-Zel'dovich Effect Survey for High Redshift Clusters

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    Interferometric observations of the Sunyaev-Zel'dovich Effect (SZE) toward clusters of galaxies provide sensitive cosmological probes. We present results from 1 cm observations (at BIMA and OVRO) of a large, intermediate redshift cluster sample. In addition, we describe a proposed, higher sensitivity array which will enable us to survey large portions of the sky. Simulated observations indicate that we will be able to survey one square degree of sky per month to sufficient depth that we will detect all galaxy clusters more massive than 2x10^{14} h^{-1}_{50}M_\odot, regardless of their redshift. We describe the cluster yield and resulting cosmological constraints from such a survey.Comment: 7 pages, 6 figures, latex, contribution to VLT Opening Symposiu

    Parameter Estimation from Improved Measurements of the Cosmic Microwave Background from QUaD

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    We evaluate the contribution of cosmic microwave background (CMB) polarization spectra to cosmological parameter constraints. We produce cosmological parameters using high-quality CMB polarization data from the ground-based QUaD experiment and demonstrate for the majority of parameters that there is significant improvement on the constraints obtained from satellite CMB polarization data. We split a multi-experiment CMB data set into temperature and polarization subsets and show that the best-fit confidence regions for the ΛCDM six-parameter cosmological model are consistent with each other, and that polarization data reduces the confidence regions on all parameters. We provide the best limits on parameters from QUaD EE/BB polarization data and we find best-fit parameters from the multi-experiment CMB data set using the optimal pivot scale of k_p = 0.013 Mpc^(–1) to be {h^2Ω_c, h^2Ω_b, H_0, A_s, n_s, τ} = {0.113, 0.0224, 70.6, 2.29 × 10^(–9), 0.960, 0.086}
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