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  • open boundaries  (2)
  • Anal sonography  (1)
  • Analytical Chemistry and Spectroscopy  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Sonographic, manometric, and myographic evaluation of the anal sphincters morphology and function (1993)
    Springer
    Diseases of the colon & rectum 36 (1993), S. 1037-1041 
    Details
    ISSN: 1530-0358
    Keywords: Anorectal manometry ; Transcutaneous electromyography ; Anal sonography ; Defecation disorders
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract PURPOSE: A direct comparison of anal sphincter physiology (muscle performance and anatomy-muscle thickness) has not yet been undertaken but may be of importance in patients with defecation disorders. METHODS: We evaluated 15 healthy volunteers by means of anorectal manometry to determine pressure functions of the internal and external anal sphincter. Transcutaneous electromyography was recorded to assess the electrical activity of the external anal sphincter. Thickness of the anal sphincter muscles was measured sonographically from within the anal canal with dorsal projection using a 7.5-MHz 360° rectal panorama scanner. RESULTS: It was shown that neither is the muscle thickness of the external anal sphincter during rest (6.26±1.02 mm) or during squeezing (7.40±1.39 mm) correlated to its squeeze pressure (138.8±15.2 mmHg), nor is the diameter of the internal anal sphincter (2.09±0.58 mm) correlated to its resting pressure (61.1±15.2 mmHg). Finally, the thicker the internal anal sphincter muscle, the lower the electrical activity of the external anal sphincter during squeezing (r=0.74,P 〈0.001). CONCLUSION: It is concluded that both manometry to assess sphincter function and sonography to determine sphincter morphology are important measures in the evaluation of continence function.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02047296
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Matrix-assisted laser desorption using a fast-atom bombardment ion source and a magnetic mass spectrometer (1992)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 6 (1992), S. 298-302 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A conventional fast-atom bombardment (FAB) ion source was used to achieve matrix-assisted laser desorption (MALD) in a high-mass, double-focusing, magnetic mass spectrometer. The pulsed ion signals generated by irradiation of a mixture of sample and matrix (2,5-dihydroxybenzoic acid) with either a XeF excimer Laser (353 nm) or a nitrogen laser (337 nm) were recorded with a focal-plane detector. A resolution (full-width at half maximum) of 4500 was achieved at m/z 1347.7 (the peptide substance P), 2500 for CsI cluster ions at m/z 10005.7, and 1250 for the isotope cluster of the small protein cytochrome c (horse) [M+H]+=m/z 12360 (average). Sensitivity is demonstrated with 11 fmol of substance P. A survey scan is taken to prodluce a better signal-to-noise ratio. In addition to higher sensitivity and lower matrix interference, lthe advantage of MALD over FAB is the former's lower susceptibility to the presence of salts, and competition between hydrophobic and bydrophilic components of a mixture. This feature is demonstrated by the complete MALD spectrum of a crude partial tryptic digest of spedrm-whale apomyoglobin, containing 24 peptides, representing the entire sequence of this protein.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290060415
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    On boundary conditions for unbounded flows (1995)
    Chichester : Wiley-Blackwell
    Communications in Numerical Methods in Engineering 11 (1995), S. 179-185 
    Details
    ISSN: 1069-8299
    Keywords: finite elements ; fluid flow ; open boundaries ; Sommerfield boundary conditions ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: We examine a method to impose boundary conditions on arbitrary boundaries, introduced to make domains of infinite extent finite for the purpose of numerical calculations, when a finite element discretization based on linear, bilinear or trilinear elements is used, in one, two or three dimensions, respectively. In particular, we look at the so-called ‘free’ boundary condition, which consists in retaining the boundary integrals generated by the weighted-residuals formulation along the open boundaries and adding them to the stiffness matrix. We show that this procedure is exactly equivalent to imposing on the boundary nodes a Sommerfeld radiation condition in one dimension, and a slightly modified form of the Sommerfeld boundary condition in two and three dimensions. We also show that the procedure is not applicable to the purely elliptic case.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cnm.1640110211
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    BOUNDARY CONDITIONS FOR FINITE ELEMENT SIMULATIONS OF CONVECTIVE FLOWS WITH ARTIFICIAL BOUNDARIES (1996)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 39 (1996), S. 1053-1071 
    Details
    ISSN: 0029-5981
    Keywords: finites elements ; open boundaries ; fluid flow ; natural boundary conditions ; Sommerfeld raiation condition ; Navier-Stokes equations ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: We examine the use of natural boundary conditions and conditions of the Sommerfeld type for finite element simulations of convective transport in viscous incompressible flows. We show that natural boundary conditions are superior in the sense that they always provide a correct boundary condition, as opposed to the Sommerfeld-type conditions, which can lead to a singular formulation and a great loss of accuracy. For the Navier-Stokes equations, the natural boundary conditions must be combined with a simple method to eliminate perturbations on the pressure at the open boundary, which is the source of most errors.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
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