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  • Springer  (147)
  • Wiley  (48)
  • Blackwell Science Ltd
  • International Union of Crystallography
  • 2000-2004
  • 1990-1994  (199)
  • 1935-1939
  • 1992  (108)
  • 1990  (91)
  • 1
    Electronic Resource
    Electronic Resource
    Ecological and evolutionary implications of digestive processes: Bird preferences and the sugar constituents of floral nectar and fruit pulp (1992)
    Springer
    Cellular and molecular life sciences 48 (1992), S. 544-551 
    Details
    ISSN: 1420-9071
    Keywords: Bird feeding preferences ; digestion ; intestinal enzymes ; sucrase ; fruit ; nectar
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Plants pollinated and dispersed by different groups of birds offer different kinds of sugars in nectar and fruit pulp. The preferences and physiological traits of avian pollinators and seed dispersers are broadly correlated with the sugar composition of the nectar and fruit that they feed on and appear to have influenced the evolution of the sugar composition of the rewards that plants offer. Hummingbirds prefer sucrose whereas many nectar- and fruit-eating passerines prefer glucose and fructose. Preference for hexoses in passerines seems to be associated with poor sucrose assimilation resulting from two physiological mechanisms: lack of intestinal sucrase activity and fast passage rates. Sucrase activity absence appears to be restricted to a single phylogenetic group (the sturnid-muscicapid lineage). Fast passage rates seem to be characteristic of many small frugivores and to hinder the assimilation of complex nutrients that require hydrolysis before absorption. Hummingbirds have extremely specialized digestive traits that allow them to assimilate sucrose at high rates and with extremely high efficiency. These specialized digestive traits appear not to be present in many nectar-feeding passerines.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01920237
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  • 2
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    Ecological and evolutionary implications of digestive processes: Bird preferences and the sugar constituents of floral nectar and fruit pulp (1992)
    Springer
    Details
    Publication Date: 1992-06-01
    Print ISSN: 0014-4754
    Topics: Biology , Medicine
    Published by Springer
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  • 3
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    Human melanotransferrin (p97) has only one functional iron-binding site (1992)
    Wiley
    Details
    Publication Date: 1992-02-24
    Print ISSN: 0014-5793
    Electronic ISSN: 1873-3468
    Topics: Biology , Chemistry and Pharmacology
    Published by Wiley on behalf of Federation of European Biochemical Societies.
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    PAPER CURRENT
  • 4
    Electronic Resource
    Electronic Resource
    Erbium fibre amplifiers and lasers (1992)
    Springer
    Optical and quantum electronics 24 (1992), S. 517-538 
    Details
    ISSN: 1572-817X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract Erbium-doped fibre amplifiers and lasers have been the subject of intense research and development over the last five years. It is hoped that this review will serve as an introduction to the main device concepts and make accessible the rapidly expanding body of literature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00619752
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  • 5
    Electronic Resource
    Electronic Resource
    Information transmission during intra- and interspecific courtship inEphestia elutella andCadra figulilella (1990)
    Springer
    Journal of insect behavior 3 (1990), S. 589-602 
    Details
    ISSN: 1572-8889
    Keywords: Courtship ; information theory ; communication ; behavioral analysis ; Ephestia elutella ; Cadra figulilella
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Using information theory, courtship posturing in the moths Ephestia elutella(Hübner) and Cadra figulilella(Gregson) was analyzed for information transmission, which was partitioned into autocovariability (intraindividual transmission) and cross-covariability (interindividual transmission). This two-factor analysis was sufficient to account for more than 60% of the behavioral variance in males of E. elutellaand in both sexes of C. figulilelladuring intraspecific courtships; however, there were large residual variances in the behavior of male and female C. figulilelladuring interspecific courtships and in E. elutellafemales during both inter- and intraspecific courtships. In E. elutella,significant levels of transmission were attributable to both inter- and intraindividual effects, whereas in C. figulilella,only autocovariability was high and no interindividual communication could be assigned to courtship postures. Although courtship in these two species was qualitatively very similar and males readily courted nonconspecific females, high levels of reproductive isolation resulted from courtship. Male C. figulilellahad 94% fewer copulations with E. elutellafemales than with conspecific females and E. elutellamales had 78% fewer copulations with C. figulilellafemales than with conspecifics. These reductions were due to a differential response in both females and males, causing inter-specific courtships to be terminated much earlier than intraspecific courtships. This discrimination indicates that interindividual communication was indeed occurring during courtship and was only partially measured by analysis of postures. Thus, communication took place largely in some other modality, most likely the chemical modality, where species specificity is suggested for both male and female pheromones.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01052330
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  • 6
    Electronic Resource
    Electronic Resource
    Reduction of the response to sex pheromone in the oriental fruit moth,Grapholita molesta (Lepidoptera: Tortricidae) following successive pheromonal exposures (1992)
    Springer
    Journal of insect behavior 5 (1992), S. 347-363 
    Details
    ISSN: 1572-8889
    Keywords: oriental fruit moth ; Grapholita molesta ; sex pheromone ; habituation ; spontaneous recovery ; aging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effects of prior pheromonal experience upon the pheromone- mediated upwind flight response was examined in the oriental fruit moth, Grapholita molesta(Busck) (Lepidoptera: Tortricidae). Adult male G. molestawere subjected to a parallel series of staggered and repeated pheromonal exposures in a sustained-flight wind tunnel. Levels of response to pheromone in male G. molestasignificantly decreased in a (a) rectilinear function with increased ages of individuals, (b) logarithmic function of successive trials, and (c) steeper logarithmic function of successive trials with increased dosage of sex pheromone. The baseline levels of responding were not affected by either the (a) dosage of sex pheromone, (b) posteclosion ages of individuals for their initial exposures once the main effect of age itself was estimated, (c) elapsed time in hours between trials, or (d) discrete days of testing as integral intervals, disregarding hours within days.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01049843
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  • 7
    Electronic Resource
    Electronic Resource
    MaleHeliothis virescens maintain upwind flight in response to experimentally pulsed filaments of their sex pheromone (Lepidoptera: Noctuidae) (1992)
    Springer
    Journal of insect behavior 5 (1992), S. 669-687 
    Details
    ISSN: 1572-8889
    Keywords: Heliothis virescens ; Noctuidae ; Lepidoptera ; upwind flight ; sex pheromone ; filaments
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Aspects of the intermittent fine structure of an odor plume were mimicked and experimentally modified in the wind tunnel using an air-pulsing device. Filaments of a behaviorally active blend of six sex-pheromone components created by the device in a temporally regular fashion elicited sustained upwind flight and source location in male Heliothis virescens.Males did not exhibit sustained upwind flight in significant numbers until a frequency of 4 filaments/s was delivered, at a loading of 1 μg of the major component, Z11-16: Ald, with the other components loaded at their appropriate ratios. A loading of 10 μg Z11-16: Ald was found to be optimal at this filament delivery rate. Electroantennogram recordings to different filament delivery rates of the complete blend indicated that a stationary male antenna can respond to the pulse rates used in this study. Importantly, when a main component necessary for upwind flight, Z9-14:Ald, was isolated into its own filaments and pulsed alternately against filaments of the five other components (including the other component essential for upwind flight, Z11-16: Ald), upwind flight to the source was significantly reduced (9%) compared to upwind flight and source location in response to filaments composed of the entire blend (30%), indicating that the complete pheromone blend must arrive on the antenna simultaneously for optimal evocation of sustained upwind progress. Neurophysiological evidence from other studies suggests that higher-order interneurons whose phasic response is enhanced when the entire blend is presented simultaneously may be of importance in explaining this behavioral difference stemming from synchronous vsasynchronous arrival of the components.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01047979
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  • 8
    Electronic Resource
    Electronic Resource
    A problem identification taxonomy for classification and automated formulation of multiple objective linear programming models (1992)
    Springer
    Annals of operations research 38 (1992), S. 1-16 
    Details
    ISSN: 1572-9338
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Economics
    Notes: Abstract This paper presents a knowledge-based Decision Support System (DSS) for classification, formulation and solution of multiple objective linear programming problems. The authors propose a generic taxonomy which is used to classify commonly encountered types of linear programming problems. Classification of the problem, vis-à-vis the proposed taxonomy, is based on the interaction with the user to determine the attributes which best describe the context or setting of the problem. A total of twenty-four problem types are included in the taxonomy. Following classification, a problem type-specific rule base is invoked to assist the user in constraint formulation. A product blending linear programming problem is used to demonstrate this component of the system since these types of problems typically include more varied constraints, including ratio as well as additive types. A second rule base is invoked for formulation of the multiple criteria objective function, model solution and sensitivity analysis. An initial goal prioritization scheme is obtained by use of the Analytical Hierarchy Process [17]; the optimal goal ordering is obtained by interaction with the user in the form of pairwise attribute value tradeoffs. The system developed is intended for use by the OR-naive user who is more familiar with the content of a problem than he/she is with the mathematical tools needed to formulate and solve such models. The system is a model management tool designed to interpret user inputs and translate those inputs into a solvable multiple objective LP. This interface alleviates the technical burdens of content specification and solution. The approach expands previous formulation tools, such as those based on natural language processing [8], to a broader range of problem types in a multiple criteria environment. The system was implemented on a personal computer using VP-Expert, BASIC and LINDO, and is demonstrated on a multiple objective blending problem. The ability of the approach to accurately classify LP problems was tested on thirty-six subjects. Results suggest that correct classification of problems was more likely to occur when the system was used.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02283649
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  • 9
    Electronic Resource
    Electronic Resource
    Interval Newton/generalized bisection when there are singularities near roots (1990)
    Springer
    Annals of operations research 25 (1990), S. 181-196 
    Details
    ISSN: 1572-9338
    Keywords: Nonlinear algebraic systems ; Newton's method ; interval arithmetic ; Gauss-Seidel method ; global optimization ; singularities
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Economics
    Notes: Abstract Interval Newton methods in conjunction with generalized bisection are important elemetns of algorithms which find theglobal optimum within a specified box X ⊂ ℝn of an objective function ϕ whose critical points are solutions to the system of nonlinear equationsF(X)=0with mathematical certainty, even in finite presision arithmetic. The overall efficiency of such a scheme depends on the power of the interval Newton method to reduce the widths of the coordinate intervals of the box. Thus, though the generalized bisection method will still converge in a box which contains a critical point at which the Jacobian matrix is singular, the process is much more costly in that case. Here, we propose modifications which make the generalized bisection method isolate singular solutions more efficiently. These modifications are based on an observation about the verification property of interval Newton methods and on techniques for detecting the singularity and removing the region containing it. The modifications assume no special structure forF. Additionally, one of the observations should also make the algorithm more efficient when finding nonsingular solutions. We present results of computational experiments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02283694
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  • 10
    Electronic Resource
    Electronic Resource
    Anticancer agent development. 5. X-ray structure and1H nmr spectral analysis of (1α,2α,5α,6α)-2,6-bis(3,4-methylenedioxyphenyl)-3,7-dioxabicyclo[3.3.0]octane-4,8-dione (1990)
    Springer
    Journal of chemical crystallography 20 (1990), S. 327-333 
    Details
    ISSN: 1572-8854
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The title compound, C20H14O8, Mr=382.3, crystallized from chloroform in the centric space group P¯1 witha=6.516(4),b=6.798(3),c=9.545(7) Å,α=85.31(5),β=73.87(5), γ=79.59(4)°,V=399.2 Å3, and Dcalc=1.59 g cm−3 forZ=1. Least-squares refinement of 1035 observed [Fo≥5σ(Fo)] reflections led to the final agreement index ofR=0.074. The molecule resides on a crystallographic center of inversion and is disordered into two different conformations. This manifests itself as a 50/50 disorder at O(4), C(2), and C(3). The observed structure reveals acis relationship between the bridgehead hydrogen atoms and the aryl rings. The 90 MHz1H nmr spectrum of the title compound exhibits an AA′XX′ spin system with a H(1)C(2) to H(1)C(3) and H(1)C(2)′ to H(1)C(3)′ coupling constant of 2.8 Hz. Computer spectral simulation and Karplus equation analysis are utilized to illustrate a relaxation of the torsion angles between H(1)C(2) and H(1)C(3), and H(1)C(2)′ and H(1)C(3)′ is solution.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01274139
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