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  • 1
    Electronic Resource
    Electronic Resource
    Shallow crustal structure beneath the Juan de Fuca Ridge from 2-D seismic refraction tomography (1990)
    Oxford, UK : Blackwell Publishing Ltd
    Geophysical journal international 100 (1990), S. 0 
    Details
    ISSN: 1365-246X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: The formation of oceanic lithosphere along ocean ridges, and the role that crustal magma chambers play in the accretionary process, continue to be fundamental issues in plate tectonics. To address these issues, a multireceiver airgun/ocean-bottom seismograph refraction line was shot across the Endeavour segment of the Juan de Fuca Ridge near 48° N, 129° W. 2-D traveltime tomography applied to the data results in a three-layer model for the upper crust. Layer 1 is 250–650 m thick, with v1= 2.5 km s−1 and ∇Vzv1= 0.5 s−1. Layer 2 is ∼800 m thick, v2= 4.8 km s−1 and ∇Vzv2= 1.0 s−1. Layer 1 and layer 2 probably represent the sequence of extrusives and the transition to layer 3 (v3= 5.8 km s−1, ∇Vzv3= 0.5 s−1) is associated with the extrusives-dike complex transition. An abrupt velocity transition between layer 1 and layer 2 may be a metamorphic front within the basalt pillows or it may be the depth to which surface fissures penetrate. A low-velocity anomaly (velocities decreased by 〈 0.45 km s−1) exists beneath the ridge in layer 2 and upper layer 3. It is interpreted as a zone of increased fracture porosity and/or permeability associated with axial hydrothermal circulation, and correlates reasonably well with a sub-axial reflector. No evidence is found for the existence of a crustal magma chamber in the depth range of 1.5–3.5 km sub-bottom. However, the velocity anomalies observed in layer 3 suggest that crustal temperatures in this layer are elevated by 150–250°C beneath and to the east of the ridge relative to temperatures west of the ridge.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-246X.1990.tb00690.x
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  • 2
    Electronic Resource
    Electronic Resource
    A penalty function approach for solving bi-level linear programs (1993)
    Springer
    Journal of global optimization 3 (1993), S. 397-419 
    Details
    ISSN: 1573-2916
    Keywords: Bi-level programming ; penalty function ; non-convex optimisation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract The paper presents an approach to bi-level programming using a duality gap—penalty function format. A new exact penalty function exists for obtaining a global optimal solution for the linear case, and an algorithm is given for doing this, making use of some new theoretical properties. For each penalty parameter value, the central optimisation problem is one of maximising a convex function over a polytope, for which a modification of an algorithm of Tuy (1964) is used. Some numerical results are given. The approach has other features which assist the actual decisionmaking process, which make use of the natural roles of duality gaps and penalty parameters. The approach also allows a natural generalization to nonlinear problems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01096412
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  • 3
    Electronic Resource
    Electronic Resource
    Extension of the Frank-Wolfe algorithm to concave nondifferentiable objective functions (1993)
    Springer
    Journal of optimization theory and applications 78 (1993), S. 283-301 
    Details
    ISSN: 1573-2878
    Keywords: Optimization ; concave functions ; subgradients
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract In this paper, we provide the theoretical foundations of an extension of the Frank-Wolfe algorithm for concave continuously differentiable objective functions to concave nondifferentiable objective functions, using a subgradient approach. The main theorem extends the results of Frank and Wolfe. A key main assumption is examined in the context of some special cases via three lemmas. A comparison is made with other subgradient approaches, and consideration is given to the two subproblem optimizations arising in the modified algorithm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00939671
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  • 4
    Electronic Resource
    Electronic Resource
    Least elements revisited (1990)
    Springer
    Journal of optimization theory and applications 65 (1990), S. 117-128 
    Details
    ISSN: 1573-2878
    Keywords: Multiple objectives ; least elements ; linear problems ; pre-Leontief matrices ; inverse notions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract Least element theory is extended, for linear problems, to general multiple-objective problems, and the pre-Leontief matrix and left-hand matrix inverse notions are generalized.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00941163
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  • 5
    Electronic Resource
    Electronic Resource
    Computational approaches to variance-penalised Markov decision processes (1992)
    Springer
    OR spectrum 14 (1992), S. 79-83 
    Details
    ISSN: 1436-6304
    Keywords: Markov decision processes ; variance penalty ; parametric algorithms ; Markov-Entscheidungsprozesse ; Varianz-Strafkosten ; parametrische Verfahren
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Economics
    Description / Table of Contents: Zusammenfassung Für ein Markov-Entscheidungsmodell, in dem der Durchschnittsgewinn um einen Teil der mittleren Varianz vermindert wird, werden drei Typen von Lösungsverfahren entwickelt, und zwar parametrische lineare Programmierung, parametrische Lagrange-Optimierung und parametrische Politik-Iterations-Algorithmen.
    Notes: Summary This paper develops three computational approaches for solving a variance-penalised Markov decision process, viz. parametric linear programming, parametric Lagrangean programming, and a parametric policy space approach.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01720350
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  • 6
    Electronic Resource
    Electronic Resource
    A mathematical programming approach to a problem in variance penalised Markov decision processes (1994)
    Springer
    OR spectrum 15 (1994), S. 225-230 
    Details
    ISSN: 1436-6304
    Keywords: Markov decision processes ; ɛ-optimal ; variance ; Markov'sche Entscheidungsprozesse ; ɛ-Optimalität ; Gewinnvarianz
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Economics
    Description / Table of Contents: Zusammenfassung In dieser Arbeit geben wir drei Algorithmen zur Lösung eines stochastischen dynamischen Problems an. Dabei wird ein optimaler Ausgleich zwischen erwartetem Gewinn und Gewinnvarianz pro Zeiteinheit gesucht. Die Algorithmen liefern für beliebigesɛ〉0 jeweilsɛ-optimale Lösungen.
    Notes: Abstract In this paper we present three algorithms for solving a problem in which it is required to get an optimal compromise between the average expected reward per unit time and the variance of the reward per unit time. The algorithms lead to anɛ-optimal solution, whereɛ〉0 is arbitrary.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01719453
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  • 7
    Electronic Resource
    Electronic Resource
    Immunofluorescent localization of pig complement component 3, regardless of the presence or absence of detectable immunoglobulins, in hyperacutely rejected heart xenografts (1992)
    Springer
    Journal of molecular histology 24 (1992), S. 102-109 
    Details
    ISSN: 1573-6865
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Rabbit heart xenografts transplanted into the neck of newborn pigs were all hyperacutely rejected within two hours regardless of the presence or absence of detectable endogenous immunoglobulins (Ig). Cryostat tissue sections were prepared from the rejected rabbit hearts and incubated with sheep polyclonal antibodies against pig complement component 3 (C3), pig IgG and pig IgM. Specific immunoreaction was visualized by fluorescein-conjugated antibodies to sheep IgG. C3 was localized mainly on the surfaces of vascular endothelial as well as myocardial cells, and the localization was not dependent upon the presence of pig immunoglobulins within the same tissue. Both pig IgG and IgM were detected only in the heart xenografts transplanted into suckled pigs, whereas no trace of immunoglobulin was found in those transplanted into circulating antibody-free presuckled pigs. Treatment with cobra venom factor (which inhibits complement activity) prior to transplantation prolonged xenograft survival and completely abolished C3 immunostaining. The results provide new evidence at the histochemical level that the alternative pathway of complement is involved in hyperacute xenograft rejection of the species combination (rabbit to pig) used in this study.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01082446
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  • 8
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    Computational approaches to variance-penalised Markov decision processes (1992)
    Springer
    Details
    Publication Date: 1992-06-01
    Print ISSN: 0171-6468
    Electronic ISSN: 1436-6304
    Topics: Mathematics , Economics
    Published by Springer
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  • 9
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    A mathematical programming approach to a problem in variance penalised Markov decision processes (1994)
    Springer
    Details
    Publication Date: 1994-12-01
    Print ISSN: 0171-6468
    Electronic ISSN: 1436-6304
    Topics: Mathematics , Economics
    Published by Springer
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  • 10
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    Extension of the Frank-Wolfe algorithm to concave nondifferentiable objective functions (1993)
    Springer
    Details
    Publication Date: 1993-08-01
    Print ISSN: 0022-3239
    Electronic ISSN: 1573-2878
    Topics: Mathematics
    Published by Springer
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