Search Results - (Author, Cooperation:A. J. Welch)

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  1. 1
    Staff View
    Publication Date:
    2013-05-15
    Publisher:
    Nature Publishing Group (NPG)
    Print ISSN:
    0028-0836
    Electronic ISSN:
    1476-4687
    Topics:
    Biology
    Chemistry and Pharmacology
    Medicine
    Natural Sciences in General
    Physics
    Keywords:
    Angiosperms/*genetics ; DNA, Intergenic/genetics ; *Evolution, Molecular ; Gene Duplication/genetics ; Genes, Plant/genetics ; Genome, Plant/*genetics ; Models, Genetic ; Solanum/genetics ; Synteny/genetics ; Vitis/genetics
    Published by:
    http://www.nature.com/

    Latest Papers from Table of Contents or Articles in Press
  2. 2
    BUDDERY, J. H. ; WELCH, A. J. E.

    [s.l.] : Nature Publishing Group
    Published 1951
    Staff View
    ISSN:
    1476-4687
    Source:
    Nature Archives 1869 - 2009
    Topics:
    Biology
    Chemistry and Pharmacology
    Medicine
    Natural Sciences in General
    Physics
    Notes:
    [Auszug] The boride and silicide phases were synthesized by heating weighed quantities of the pure elements, suit-ably mixed, in evacuated and sealed silica capsules, at 1,000-1,200 C. ; in most cases the products were cooled slowly. X-ray powder photographs were taken (usually with unfiltered copper ...
    Type of Medium:
    Electronic Resource
    URL:
    http://dx.doi.org/10.1038/167362a0

    Articles: DFG German National Licenses
  3. 3
    Welch, A. J. ; Cheong, Wai -Fung
    Springer
    Published 1989
    Staff View
    ISSN:
    1435-604X
    Source:
    Springer Online Journal Archives 1860-2000
    Topics:
    Medicine
    Physics
    Technology
    Notes:
    Abstract Our theoretical assessment of laser balloon angioplasty (LBA) begins with a solution of the popular P1 (diffusion) approximation to the radiative transport equation to map the optical field in an axisymmetric, finite annulus surrounding an infinitely long hollow cylindrical vessel. The inner surface is irradiated by diffuse light at 1.06 μm and delivered by a spiral segment of fiberoptic positioned centrally inside an inflated balloon. The present model considers only a single layer of optically homogenous arterial wall because the hollow is presumbly filled with a non-absorbing and non-scattering fluid. The cylindrical enclosure collects reflected light and redirects it back onto the inner surface. Our model accounts for this ‘integrating’ behavior, unique to enclosures. Absorption of the laser light then raises tissue temperature. The resultant transient and spatial temperature distribution is calculated with an implicit Finite Difference algorithm based on the heat conduction equation. Multiple concentric layers, each with different thermal properties from the other, are considered. However, changes in optical and thermal properties with temperature, and thermal phase transitions have been omitted in the present model. Finally, the Arrhenius rate process integral is applied for damage calculations. The temperature patterns of three delivery dose patterns — constant 22.5W (20s), ramp sequences of 40W(5s)-30W(5s)-10W(10s), and 35W(5s)-25W(5s)-15W(10s) — suggest that the second ramp dose may be most efficacious because it generates the longest temperature ‘plateau’ at the intimal-medial junction. Simulations of a hot metallic probe have a consistently higher surface damage than that obtained by LBA of equivalent energy output.
    Type of Medium:
    Electronic Resource
    URL:
    http://dx.doi.org/10.1007/BF02276670

    Articles: DFG German National Licenses
  4. 4
    Parish, R. V. ; Wynd, A. J. ; Welch, A. J.
    Springer
    Published 1990
    Staff View
    ISSN:
    1572-9540
    Source:
    Springer Online Journal Archives 1860-2000
    Topics:
    Physics
    Notes:
    Abstract The first197Au Mössbauer spectra for compounds in which gold is bound to boron clusters are reported, and their relation to the structure and bonding involved are discussed.
    Type of Medium:
    Electronic Resource
    URL:
    http://dx.doi.org/10.1007/BF02101069

    Articles: DFG German National Licenses
  5. 5
    Torres, J. H. ; Ghaffari, S. ; Welch, A. J.
    Springer
    Published 1990
    Staff View
    ISSN:
    1741-0444
    Keywords:
    Angioplasty ; Atherosclerosis ; Feedback ; Infra-red ; Laser probe ; Temperature
    Source:
    Springer Online Journal Archives 1860-2000
    Topics:
    Biology
    Chemistry and Pharmacology
    Medicine
    Notes:
    Abstract The metal-tipped fibre or ‘laser probe’ developed for angioplasty comprises a metallic probe at the end of an optical fibre. The probe is heated by an argon or Nd: YAG laser and applied against the tissue to be vapourised. The heated probe generates infra-red radiation which is proportional to the temperature of the probe. The paper investigates the feasibility of a feedback control system that measures the temperature of the probe by detecting the infra-red radiation transmitted back through the fibre. The probe was initially heated by physical contact with a hot surface, and then by an argon laser via the optical fibre. The returning IR radiation was sensed by a lead sulphide detector, while probe temperature was simultaneously measured by a thermocouple. Temperatures as low as 200°C were measured through a 5 m long fibre during the laser heating of the probe. The detector signal increased in an exponential fashion as the probe temperature increased. A resolution of 1°C was obtained at a probe temperature of 400°C. It can be concluded that, for the laser probe, it is feasible to use a feedback control system which measures the infra-red radiation transmitted back through the same fibre that carries the heating laser light.
    Type of Medium:
    Electronic Resource
    URL:
    http://dx.doi.org/10.1007/BF02441670

    Articles: DFG German National Licenses