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  • 1
    Electronic Resource
    Electronic Resource
    Multifocal epithelioid angiosarcoma of the small intestine (2000)
    Springer
    Virchows Archiv 437 (2000), S. 90-94 
    Details
    ISSN: 1432-2307
    Keywords: Key words Small intestine ; Epithelioid angiosarcoma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  A 67-year-old man presented with weight loss, intermittent severe abdominal pain and melaena. Initial radiology (including abdominal ultrasonography), gastroscopy and colonoscopy did not demonstrate any lesions that could explain the complaints. Three weeks later, upper gastrointestinal and small-bowel barium studies revealed two areas in the small intestine with an abnormal mucosal pattern. Explorative laparotomy revealed three tumoral lesions. Three partial enterectomies were performed. Gross examination showed centrally depressed dark reddish tumoral lesions extending from the mucosa throughout the full thickness of the bowel wall (diameter varying between 1.6 cm and 2.2 cm). The tumours, composed of large, plump, polygonal cells showing little architectural differentiation, were mainly situated in submucosa and muscularis propria. The growth pattern appeared rather solid. The epithelioid cells showed pronounced nuclear pleomorphism and atypia with central large nucleoli. There were several small blood vessels with occasional anaplastic endothelial cells. Immunohistochemical staining demonstrated an intense expression of CD 31, CD 34, factor VIII related antigen and keratin. This supported the diagnosis of an epithelioid angiosarcoma. The patient died 3 months after diagnosis. Tumours of the small intestine are very rare, and angiosarcomas of the small intestine are even more rare. Epithelioid variants have only been described in two patients and only one of these had a multifocal presentation. The prognosis is very poor. Because of the epithelioid growth pattern and the cytokeratin expression, these tumours may erroneously be diagnosed as a carcinoma.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004280000183
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  • 2
    Electronic Resource
    Electronic Resource
    Finite elements for viscoelastic flows with change of type (1993)
    Springer
    Theoretical and computational fluid dynamics 4 (1993), S. 289-308 
    Details
    ISSN: 1432-2250
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract We compare several mixed finite-element methods for calculating viscoelastic flows where the vorticity equation changes type from elliptic to hyperbolic whenever inertia is taken into account. The flows are perturbed viscometric flows with slightly wavy walls. The perturbed uniform flow gives rise to a closed-form analytical solution. We examine five different finite-element algorithms; it is found that the so-called SU4×4 and EVSS methods perform much better than the other three. We also examine a number of features proper to flows with change of type, such as the propagation of disturbances along characteristic lines of the vorticity equation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00418778
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Numerical simulation of delayed die swell (1990)
    Springer
    Rheologica acta 29 (1990), S. 1-10 
    Details
    ISSN: 1435-1528
    Keywords: Delayed dieswell ; criticalextrusionvelocity ; Oldroyd-B ; viscoelasticMach number ; Giesekus fluid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract In a recent paper, Joseph et al. showed that, for a number of viscoelastic fluids, one can observe the phenomenon of delayed die swell beyond a critical extrusion velocity, or beyond a critical value of the viscoelastic Mach number. Giesekus had also observed that delayed die swell is a critical phenomenon. In the present paper, we find a set of material and flow parameters under which it is possible to simulate delayed die swell. For the viscoelastic flow calculation, we use the finite element algorithm with sub-elements for the stresses and streamline upwinding in the discretized constitutive equations. For the free surface, we use an implicit technique which allows us to implement Newton's method for solving the non-linear system of equations. The fluid is Oldroyd-B which, in the present problem, is a singular perturbation of the Maxwell fluid. The results show very little sensitivity to the size of the retardation time. We also show delayed die swell for a Giesekus fluid.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01331795
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    Paper (German National Licenses)
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