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  • ddc:000  (17)
  • Hexahydro-difenidol  (1)
  • Macrometastases  (1)
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  • 1
    Digitale Medien
    Digitale Medien
    Is Routine Intraoperative Frozen-Section Examination of Sentinel Lymph Nodes in Breast Cancer Worthwhile? (2000)
    Springer
    Annals of surgical oncology 7 (2000), S. 651-655 
    Details
    ISSN: 1534-4681
    Schlagwort(e): Sentinel lymph nodes ; Frozen section ; Macrometastases ; Micrometastases
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Background: Routine intraoperative frozen section (FS) of sentinel lymph nodes (SLN) can detect metastatic disease, allowing immediate axillary dissection and avoiding the need for reoperation. Routine FS is also costly, increases operative time, and is subject to false-negative results. We examined the benefit of routine intraoperative FS among the first 1000 patients at Memorial Sloan Kettering Cancer Center who had SLN biopsy for breast cancer. Methods: We performed SLN biopsy with intraoperative FS in 890 consecutive breast cancer patients, none of whom had a back-up axillary dissection planned in advance. Serial sections and immunohistochemical staining for cytokeratins were performed on all SLN that proved negative on FS. The sensitivity of FS was determined as a function of (1) tumor size and (2) volume of metastatic disease in the SLN, and the benefit of FS was defined as the avoidance of a reoperative axillary dissection. Results: The sensitivity of FS ranged from 40% for patients with T1a to 76% for patients with T2 cancers. The volume of SLN metastasis was highly correlated with tumor size, and FS was far more effective in detecting macrometastatic disease (sensitivity 92%) than micrometastases (sensitivity 17%). The benefit of FS in avoiding reoperative axillary dissection ranged from 4% for T1a (6 of 143) to 38% for T2 (45 of 119) cancers. Conclusions: In breast cancer patients having SLN biopsy, the failure of routine intraoperative FS is largely the failure to detect micrometastatic disease. The benefit of routine intraoperative FS increases with tumor size. Routine FS may not be indicated in patients with the smallest invasive cancers.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s10434-000-0651-3
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  • 2
    Digitale Medien
    Digitale Medien
    Characterization of postjunctional muscarinic receptors mediating contraction in rat anococcygeus muscle (1997)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 356 (1997), S. 671-677 
    Details
    ISSN: 1432-1912
    Schlagwort(e): Key words Rat anococcygeus muscle ; Muscarinic ; receptor subtypes ; Muscarinic agonists ; Muscarinic ; antagonists ; M3 receptors ; Stereoselectivity ; Hexahydro-difenidol
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The present study was designed to characterize the postjunctional muscarinic receptors mediating contraction in rat anococcygeus muscle by means of a series of muscarinic agonists and subtype-preferring key muscarinic antagonists. Cumulative addition of muscarinic agonists elicited concentration-dependent contractions with the following rank order of potency (pD2 values): (+)-muscarine (6.36) ≥ oxotremorine M (6.21) ≥ arecaidine propargyl ester (APE) (6.18) 〉 carbachol (5.68)=(±)-methacholine (5.65) 〉 4-(4-chlorophenyl-carbamoyloxy)-2-butynyltrimethylammonium chloride (4-Cl-McN-A-343) (4.28) 〉 4-(3-chlorophenylcarbamoyloxy)-2-butynyltrimethylammonium chloride (McN-A-343) (3.89). (+)-Muscarine, oxotremorine M, carbachol and (±)-methacholine behaved as full agonists, whereas APE, 4-Cl-McN-A-343 and McN-A-343 displayed partial agonism. The contractile responses of the rat anococcygeus muscle to (±)-methacholine were competitively antagonized by pirenzepine (pA2=6.92), 11-[[4-[4-(diethylamino)butyl]-1-piperidinyl]acetyl] 5,11-dihydro-6H-pyrido(2,3-b)(1,4)-benzodiazepine-6-one (AQ-RA 741; pA2=6.75), himbacine (pA2=7.11), (±)-p-fluoro-hexahydro-sila-difenidol (p-F-HHSiD; pA2=7.68) and the (R)- and (S)-enantiomers of hexahydro-difenidol [(R)-HHD: pA2=8.52; (S)-HHD: pA2=6.06]. A comparison of the pA2 values derived from studies of contraction in rat anococcygeus muscle with literature binding (pKi values) and functional affinities (pA2 values) obtained at native M1-M4 receptors strongly suggests that the postjunctional muscarinic receptors mediating contraction in rat anococcygeus muscle are of the M3 subtype.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/PL00005104
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  • 3
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    A New Nonlinear Elliptic Multilevel FEM Applied to Regional Hyperthermia (1998)
    Details
    Publikationsdatum: 2019-01-29
    Beschreibung: In the clinical cancer therapy of regional hyperthermia nonlinear perfusion effects inside and outside the tumor seem to play a not negligible role. A stationary model of such effects leads to a nonlinear Helmholtz term within an elliptic boundary value problem. The present paper reports about the application of a recently designed adaptive multilevel FEM to this problem. For several 3D virtual patients, nonlinear versus linear model is studied. Moreover, the numerical efficiency of the new algorithm is compared with a former application of an adaptive FEM to the corresponding instationary model PDE.
    Schlagwort(e): ddc:000
    Sprache: Englisch
    Materialart: reportzib , doc-type:preprint
    Format: application/postscript
    Format: application/pdf
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  • 4
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    Asymptotic Mesh Independence of Newton's Method Revisited (2003)
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    Publikationsdatum: 2019-01-29
    Beschreibung: The paper presents a new affine invariant theory on asymptotic mesh independence of Newton's method in nonlinear PDEs. Compared to earlier attempts, the new approach is both much simpler and more natural from the algorithmic point of view. The theory is exemplified at collocation methods for ODE boundary value problems and at finite element methods for elliptic PDE problems.
    Schlagwort(e): ddc:000
    Sprache: Englisch
    Materialart: reportzib , doc-type:preprint
    Format: application/postscript
    Format: application/pdf
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  • 5
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    Local Inexact Newton Multilevel FEM for Nonlinear Elliptic Problems (1996)
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    Publikationsdatum: 2019-01-29
    Beschreibung: The finite element setting for nonlinear elliptic PDEs directly leads to the minimization of convex functionals. Uniform ellipticity of the underlying PDE shows up as strict convexity of the arising nonlinear functional. The paper analyzes computational variants of Newton's method for convex optimization in an affine conjugate setting, which reflects the appropriate affine transformation behavior for this class of problems. First, an affine conjugate Newton--Mysovskikh type theorem on the local quadratic convergence of the exact Newton method in Hilbert spaces is given. It can be easily extended to inexact Newton methods, where the inner iteration is only approximately solved. For fixed finite dimension, a special implementation of a Newton--PCG algorithm is worked out. In this case, the suggested monitor for the inner iteration guarantees quadratic convergence of the outer iteration. In infinite dimensional problems, the PCG method may be just formally replaced by any Galerkin method such as FEM for linear elliptic problems. Instead of the algebraic inner iteration errors we now have to control the FE discretization errors, which is a standard task performed within any adaptive multilevel method. A careful study of the information gain per computational effort leads to the result that the quadratic convergence mode of the Newton--Galerkin algorithm is the best mode for the fixed dimensional case, whereas for an adaptive variable dimensional code a special linear convergence mode of the algorithm is definitely preferable. The theoretical results are then illustrated by numerical experiments with a {\sf NEWTON--KASKADE} algorithm.
    Schlagwort(e): ddc:000
    Sprache: Englisch
    Materialart: reportzib , doc-type:preprint
    Format: application/postscript
    Format: application/pdf
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  • 6
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    Interior Point Methods in Function Space (2003)
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    Publikationsdatum: 2019-01-29
    Beschreibung: A primal-dual interior point method for optimal control problems is considered. The algorithm is directly applied to the infinite dimensional problem. Existence and convergence of the central path are analyzed, and linear convergence of a short step pathfollowing method is established.
    Schlagwort(e): ddc:000
    Sprache: Englisch
    Materialart: reportzib , doc-type:preprint
    Format: application/postscript
    Format: application/pdf
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  • 7
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    Function space interior point methods for PDE constrained optimization (2004)
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    Publikationsdatum: 2019-01-29
    Beschreibung: A primal-dual interior point method for optimal control problems with PDE constraints is considered. The algorithm is directly applied to the infinite dimensional problem. Existence and convergence of the central path are analyzed. Numerical results from an inexact continuation method applied to a model problem are shown.
    Schlagwort(e): ddc:000
    Sprache: Englisch
    Materialart: reportzib , doc-type:preprint
    Format: application/postscript
    Format: application/pdf
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  • 8
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    Superlinear Convergence of the Control Reduced Interior Point Method for PDE Constrained Optimization (2005)
    Details
    Publikationsdatum: 2019-01-29
    Beschreibung: A thorough convergence analysis of the Control Reduced Interior Point Method in function space is performed. This recently proposed method is a primal interior point pathfollowing scheme with the special feature, that the control variable is eliminated from the optimality system. Apart from global linear convergence we show, that this method converges locally almost quadratically, if the optimal solution satisfies a function space analogue to a non-degeneracy condition. In numerical experiments we observe, that a prototype implementation of our method behaves in compliance with our theoretical results.
    Schlagwort(e): ddc:000
    Sprache: Englisch
    Materialart: reportzib , doc-type:preprint
    Format: application/pdf
    Format: application/postscript
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  • 9
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    The Central Path towards the Numerical Solution of Optimal Control Problems (2001)
    Details
    Publikationsdatum: 2019-01-29
    Beschreibung: A new approach to the numerical solution of optimal control problems including control and state constraints is presented. Like hybrid methods, the approach aims at combining the advantages of direct and indirect methods. Unlike hybrid methods, however, our method is directly based on interior-point concepts in function space --- realized via an adaptive multilevel scheme applied to the complementarity formulation and numerical continuation along the central path. Existence of the central path and its continuation towards the solution point is analyzed in some theoretical detail. An adaptive stepsize control with respect to the duality gap parameter is worked out in the framework of affine invariant inexact Newton methods. Finally, the performance of a first version of our new type of algorithm is documented by the successful treatment of the well-known intricate windshear problem.
    Schlagwort(e): ddc:000
    Sprache: Englisch
    Materialart: reportzib , doc-type:preprint
    Format: application/postscript
    Format: application/pdf
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  • 10
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    Global Inexact Multilevel FEM for Nonlinear Elliptic Problems (1996)
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    Publikationsdatum: 2019-01-29
    Beschreibung: The paper deals with the multilevel solution of {\em elliptic} partial differential equations (PDEs) in a {\em finite element} setting: {\em uniform ellipticity} of the PDE then goes with {\em strict monotonicity} of the derivative of a nonlinear convex functional. A {\em Newton multigrid method} is advocated, wherein {\em linear residuals} are evaluated within the multigrid method for the computation of the Newton corrections. The globalization is performed by some {\em damping} of the ordinary Newton corrections. The convergence results and the algorithm may be regarded as an extension of those for local Newton methods presented recently by the authors. An {\em affine conjugate} global convergence theory is given, which covers both the {\em exact} Newton method (neglecting the occurrence of approximation errors) and {\em inexact} Newton--Galerkin methods addressing the crucial issue of accuracy matching between discretization and iteration errors. The obtained theoretical results are directly applied for the construction of adaptive algorithms. Finally, illustrative numerical experiments with a~{\sf NEWTON--KASKADE} code are documented.
    Schlagwort(e): ddc:000
    Sprache: Englisch
    Materialart: reportzib , doc-type:preprint
    Format: application/postscript
    Format: application/pdf
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