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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Geometriae dedicata 63 (1996), S. 159-170 
    ISSN: 1572-9168
    Keywords: 52A21 ; Minkowski space ; divergence ; Laplacian ; elliptic operator ; ellipsoid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract Let (X, B) be a Minkowski space (finite-dimensional Banach space) with unit ball B. Using a Minkowski definition of unit normal to a hypersurface, a Minkowski analogue of Euclidean divergence is defined. We show that the divergence theorem holds. Using the Minkowski divergence, a Minkowski Laplacian is defined. We prove that this Laplacian is a second-order, constant-coefficient, elliptic, differential operator. Furthermore, the symbol of this Laplacian is computed and used to associate a natural Euclidean structure with (X, B).
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1435-4373
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In this multicenter, randomized, double-blind study the activity of polyI:polyC12U administered with zidovudine was evaluated in the treatment of HIV infection. Thirty-six HIV-positive, pre-AIDS individuals (100–500 CD4+ cells/mm3) who had had at least six months of zidovudine therapy received polyI:polyC12U (400 or 700 mg) or placebo twice weekly with zidovudine. PolyI:polyC12U subjects with baseline CD4+ counts≥300/mm3 showed a trend towards reduced CD4+ loss versus placebo recipients. PolyI:polyC12U subjects were more likely to exhibit positive delayed-type hypersensitivity responses than placebo recipients. Placebo subjects crossing over to polyI:polyC12U therapy demonstrated improved CD4+ and delayed-type hypersensitivity responses. PolyI: polyC12U subjects with baseline CD4+ counts≥300/mm3 were less likely to develop AIDS than similar placebo subjects. PolyI:polyC12U therapy of HIV-positive subjects restored or stabilized immune function as indexed by delayed-type hypersensitivity reactivity and, in individuals with CD4+ counts〉300/mm3, abrogated CD4+ loss and reduced disease progression. PolyI:polyC12U was generally well-tolerated in this zidovudine-treated population. No subject discontinued therapy due to an adverse reaction or aberrant laboratory parameter.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Bulletin of mathematical biology 58 (1996), S. 809-810 
    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Bulletin of mathematical biology 58 (1996), S. 513-553 
    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract An analytical model for thermal damage of retinal tissue due to absorption of laser energy by finite-sized melanin granules is developed. Since melanin is the primary absorber of visible and near-IR light in the skin and in the retina, bulk heating of tissue can be determined by superposition of individual melanin granule effects. Granules are modeled as absorbing spheres surrounded by an infinite medium of water. Analytical solutions to the heat equation result in computations that are quick and accurate. Moreover, the model does not rely on symmetric beam profiles, and so arbitrary images can be studied. The important contribution of this model is to provide a more accurate biological description of submillisecond pulse exposures than previous retinal models, while achieving agreement for longer pulses. This model can also be naturally extended into the sub-microsecond domain by including vaporization as a damage mechanism. It therefore represents the beginning of a model which can be applied across the entire pulse duration domain.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Entomologia experimentalis et applicata 80 (1996), S. 133-139 
    ISSN: 1570-7458
    Keywords: host shifts ; life history covariance ; Papilio ; genetic pleiotropy ; host range ; host specialisation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The evolution of host specialization in phytophagous insects is generally thought to involve genetic trade-offs that prevent individuals from maximizing fitness simultaneously on two or more hosts. Several hypotheses, however, have suggested that trade-offs may not be evident in experiments comparing larval performance on normal and novel hosts. Tests on survivorship, growth rate, and pupal mass among families of the swallowtail butterfly Papilio oregonius on its normal host and on a novel host provide support for these hypotheses, although they do not discriminate among them. Families differed in their relative performance on the hosts, but there was no evidence of a negative genetic correlation between hosts for any of the measures of performance. In addition, there were no correlations among the different measures, corroborating an earlier result suggesting that these different components of performance in the P. machaon species group are under at least partially separate genetic control. These results and similar results published for other insects have now produced a body of studies indicating that genetic trade-offs in individual components of larval performance may not be a major factor preventing shifts onto novel host plants. Trade-offs leading to the evolution of host specialization are more likely to involve coordination among the various components of performance together with ecological factors that allow higher fitness on one host than on others.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1570-7458
    Keywords: Corcyra cephalonica ; parasitism ; encapsulation ; host regulation ; host suitability ; Venturia canescens
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Many endoparasitoids develop successfully within a range of host instars. Parasitoid survival is highest when parasitism is initiated in earlier host instars, due to age-related changes in internal (physiological) host defences. Most studies examining fitness-related costs associated with differences in host instar have concentrated on the parasitoid, ignoring the effects of parasitism on the development of surviving hosts that have encapsulated parasitoid eggs. A laboratory experiment was undertaken examining fitness-related costs associated with encapsulation of Venturia canescens (Hymenoptera: Ichneumonidae) eggs by fifth (L5) instar larvae of Corcyra cephalonica (Lepidoptera: Pyralidae). Growth and development of both host and parasitoid were monitored in C. cephalonica larvae containing 0, 1, 2, or 4 parasitoid eggs. Adult size and fecundity of C. cephalonica did not vary with the number of eggs per host. However, there was a distinct increase in host mortality with egg number, although most parasitoids emerged from hosts containing a single egg. The most dramatic effect on the host was a highly significant increase in development time from parasitism to adult eclosion, with hosts containing 4 parasitoid eggs taking over 2.5 days longer to complete development than unparasitized larvae. The egg-to-adult development time and size of adult V. canescens did not vary with egg number per host, as demonstrated in a previous experiment using a different host (Plodia interpunctella). The results described here show that there are fitness-related costs to the host associated with resistance to parasitism.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Annals of operations research 66 (1996), S. xi 
    ISSN: 1572-9338
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Economics
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1572-9338
    Keywords: Efficiency sensitivity ; interior point algorithm ; analytic centers ; potential data errors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Economics
    Notes: Abstract The setE of extreme points which are also efficient are of basic importance in defining the efficiency frontier, from which the observations for all other DMUs are evaluated in DEA. A significant question which we address is “What variations in the data can be tolerated before the membership inE is changed?” This topic is explored using (1) a simple illustrative example, and (2) production data for 30 independent oil companies during the period 1983–1985. Data were allowed to vary simultaneously for all observations and in different subsets determined by random drawings of data for points both inE and not inE. The results were found to be robust in this study, thereby lending further support to earlier studies which also found these classifications into efficient and inefficient performers to be robust in DEA. Technical developments for these new methods of sensitivity analysis are supplied. These developments feature an application of analytic center (interior point) algorithms which ensure that the Strong Complementary Slackness Condition (SCSC) is fulfilled. The solutions satisfy a mathematical condition called “centrality”. Generally, the solutions are at interior points calledanalytic centers. At these interior points, continuity of the input-output ratios ensures that DMUs inE remain inE for at least small relative variations in the data, while empirically these properties have been found to extend to much larger variations in the data sets.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Annals of operations research 66 (1996), S. 1-45 
    ISSN: 1572-9338
    Keywords: Technical inefficiency ; mix inefficiency ; returns to scale ; congestion ; mathematical programming
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Economics
    Notes: Abstract The extensions, new developments and new interpretations for DEA covered in this paper include: (1) new measures of efficiency, (2) new models and (3) new ways of implementing established models with new results and interpretations presented that include treatments of “congestion”, “returns-to-scale” and “mix” and “technical” inefficiencies and measures of efficiency that can be used to reflect all pertinent properties. Previously used models, such as those used to identify “allocative inefficiencies”, are extended by means of “assurance region” approaches which are less demanding in their information requirements and underlying assumptions. New opportunities for research are identified in each section of this chapter. Sources of further developments and possible sources for further help are also suggested with references supplied to other papers that appear in this volume and which are summarily described in this introductory chapter.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Annals of operations research 68 (1996), S. i 
    ISSN: 1572-9338
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Economics
    Type of Medium: Electronic Resource
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