13,354 research outputs found

    Intrusive origin of the Sudbury Igneous Complex: Structural and sedimentological evidence

    Get PDF
    In recent years, many geoscientists have come to believe that the Sudbury event was exogenic rather than endogenic. Critical to a recent exogenic hypothesis is the impact melt origin of the Sudbury Igneous Complex (SIC). Such origin implies that the SIC was emplaced before deposition of the Whitewater Group, in contrast to origins in which the SIC postdates the lithification of the Onaping Formation. Structural and sedimentological evidence is summarized herein that supports an intrusion of the SIC after lithification of all Whitewater Group strata, and conflicts with the hypothesis advanced by other researchers

    Relativistic many-body calculations of the Stark-induced amplitude of the 6P1/2 -7P1/2 transition in thallium

    Full text link
    Stark-induced amplitudes for the 6P1/2 - 7P1/2 transition in Tl I are calculated using the relativistic SD approximation in which single and double excitations of Dirac-Hartree-Fock levels are summed to all orders in perturbation theory. Our SD values alpha S = 368 a0 3 and beta S= 298 a 0 3 are in good agreement with the measurements alpha S=377(8) a 0 3$ and beta S = 313(8) a 0 3 by D. DeMille, D. Budker, and E. D. Commins [Phys. Rev. A 50, 4657 (1994)]. Calculations of the Stark shifts in the 6P1/2 - 7P1/2 and 6P1/2 - 7S1/2 transitions are also carried out. The Stark shifts predicted by our calculations agree with the most accurate measured values within the experimental uncertainties for both transitions

    John Y. Templeton III: Pioneer of modern cardiothoracic surgery.

    Get PDF
    John Young Templeton III was born in 1917 in Portsmouth, Virginia, and graduated from Jefferson Medical College in 1941. He completed his residency training under Dr. John H. Gibbon, Jr., and was the first resident who worked on Gibbon\u27s heart-lung machine. After his training, he remained at Jefferson as an American Cancer Society fellow and Damon Runyon fellow and went on to become the fourth Samuel D. Gross Professor and Chair of the Department of Surgery in 1967. Dr. Templeton was the recipient of numerous grants and published over 80 papers in the field of cardiothoracic surgery. As a teacher and mentor, he was a beloved figure who placed great faith in his residents. He participated in over 60 professional societies, serving as president to many such as the Philadelphia Academy of Surgery and the Pennsylvania Association of Thoracic Surgery. He was also recognized through his many awards, in particular the John Y. Templeton III lectureship established in 1980 at Jefferson of whom Denton Cooley was the first lecturer. Dr. Templeton retired from practice in 1987. He is forever remembered as an important model of a modern surgeon evident in numerous academic achievements, the admiration and affection of his trainees, and the lives of patients that he had touched

    Absorbing systematic effects to obtain a better background model in a search for new physics

    Full text link
    This paper presents a novel approach to estimate the Standard Model backgrounds based on modifying Monte Carlo predictions within their systematic uncertainties. The improved background model is obtained by altering the original predictions with successively more complex correction functions in signal-free control selections. Statistical tests indicate when sufficient compatibility with data is reached. In this way, systematic effects are absorbed into the new background model. The same correction is then applied on the Monte Carlo prediction in the signal region. Comparing this method to other background estimation techniques shows improvements with respect to statistical and systematical uncertainties. The proposed method can also be applied in other fields beyond high energy physics

    Implementation of a Standardized Handoff System for a General Surgery Residency Program

    Get PDF
    Introduction: The I-PASS Handoff Bundle is an evidence based standardized set of educational materials designed to decrease handoff failures in patient care. Two of every three sentinel events , the most serious events reported to the Joint Commission, are due to failures of communication, including miscommunication during patient care handoffs. Implementation of the I-PASS method results in decreased medical errors and preventable adverse events There are few studies that evaluate this validated method in the context of a General Surgery resident program We aim to implement the I-PASS system into the transition of care process for General Surgery residents at our institution, and to analyze of the quality of the handoff process before and after the implementation.https://jdc.jefferson.edu/patientsafetyposters/1047/thumbnail.jp

    A Simple Model for r-Process Scatter and Halo Evolution

    Full text link
    Recent observations of heavy elements produced by rapid neutron capture (r-process) in the halo have shown a striking and unexpected behavior: within a single star, the relative abundances of r-process elements heavier than Eu are the same as the same as those of solar system matter, while across stars with similar metallicity Fe/H, the r/Fe ratio varies over two orders of magnitude. In this paper we present a simple analytic model which describes a star's abundances in terms of its ``ancestry,'' i.e., the number of nucleosynthesis events (e.g., supernova explosions) which contributed to the star's composition. This model leads to a very simple analytic expression for the abundance scatter versus Fe/H, which is in good agreement with the data and with more sophisticated numerical models. We investigate two classes of scenarios for r-process nucleosynthesis, one in which r-process synthesis events occur in only \sim 4% of supernovae but iron synthesis is ubiquitous, and one in which iron nucleosynthesis occurs in only about 9% of supernovae. (the Wasserburg- Qian model). We find that the predictions in these scenarios are similar for [Fe/H] \ga -2.5, but that these models can be readily distinguished observationally by measuring the dispersion in r/Fe at [Fe/H] \la -3.Comment: AASTeX, 21 pages, includes 4 figure

    Measurement of Electron Trapping in the CESR Storage Ring

    Full text link
    The buildup of low-energy electrons has been shown to affect the performance of a wide variety of particle accelerators. Of particular concern is the persistence of the cloud between beam bunch passages, which can impose limitations on the stability of operation at high beam current. We have obtained measurements of long-lived electron clouds trapped in the field of a quadrupole magnet in a positron storage ring, with lifetimes much longer than the revolution period. Based on modeling, we estimate that about 7% of the electrons in the cloud generated by a 20-bunch train of 5.3 GeV positrons with 16-ns spacing and 1.3x10111.3x10^{11} population survive longer than 2.3 ÎĽ\mus in a quadrupole field of gradient 7.4 T/m. We have observed a non-monotonic dependence of the trapping effect on the bunch spacing. The effect of a witness bunch on the measured signal provides direct evidence for the existence of trapped electrons. The witness bunch is also observed to clear the cloud, demonstrating its effectiveness as a mitigation technique.Comment: 6 pages, 9 figures, 28 citation

    New Results on e+e- Line Emission in U+Ta Collisions

    Full text link
    We present new results obtained from a series of follow-up e+e- coincidence measurements in heavy-ion collisions, utilizing an improved experimental set-up at the double-Orange beta-spectrometer of GSI. The collision system U+Ta was reinvestigated in three independent runs at beam energies in the range (6.0-6.4)xA MeV and different target thicknesses, with the objective to reproduce a narrow sum-energy e+e- line at ~635 keV observed previously in this collision system. At improved statistical accuracy, the line could not be found in these new data. For the ''fission'' scenario, an upper limit (1 sigma) on its production probability per collision of 1.3x10^{-8} can be set which has to be compared to the previously reported value of [4.9 +- 0.8 (stat.) +- 1.0 (syst)]x10^{-7}. In the light of the new results, a reanalysis of the old data shows that the continuous part of the spectrum at the line position is significantly higher than previously assumed, thus reducing the production probability of the line by a factor of two and its statistical significance to < 3.4sigma.Comment: 15 pages, standard LaTeX with 3 included PS figures; Submitted to Physics Letters

    Preventing Isolated Perioperative Reintubation: Who is at highest risk?

    Get PDF
    Objectives: 1. We aim to characterize IPR nationally through a retrospective review of the National Surgical Quality Improvement Program participant user file (NSQIP PUF). 2.Identify risk factors for IPR including analysis of procedure type and preoperative characteristics.https://jdc.jefferson.edu/patientsafetyposters/1041/thumbnail.jp
    • …
    corecore