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  • Springer  (150)
  • 2020-2023
  • 1985-1989  (136)
  • 1935-1939  (14)
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Mathematical programming 34 (1986), S. 48-61 
    ISSN: 1436-4646
    Keywords: Total Dual Integrality ; Hilbert Basis ; Polyhedra
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract Edmonds and Giles introduced the class of box totally dual integral polyhedra as a generalization of submodular flow polyhedra. In this paper a geometric characterization of these polyhedra is given. This geometric result is used to show that each TDI defining system for a box TDI polyhedron is in fact a box TDI system, that the class of box TDI polyhedra is in co-NP and is closed under taking projections and dominants, that the class of box perfect graphs is in co-NP, and a result of Edmonds and Giles which is related to the facets of box TDI polyhdera.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Mathematical programming 34 (1986), S. 251-264 
    ISSN: 1436-4646
    Keywords: Integer Linear Programming ; Chvátal Rank ; Cutting Planes ; Sensitivity Analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract We consider integer linear programming problems with a fixed coefficient matrix and varying objective function and right-hand-side vector. Among our results, we show that, for any optimal solution to a linear program max{wx: Ax≤b}, the distance to the nearest optimal solution to the corresponding integer program is at most the dimension of the problem multiplied by the largest subdeterminant of the integral matrixA. Using this, we strengthen several integer programming ‘proximity’ results of Blair and Jeroslow; Graver; and Wolsey. We also show that the Chvátal rank of a polyhedron {x: Ax≤b} can be bounded above by a function of the matrixA, independent of the vectorb, a result which, as Blair observed, is equivalent to Blair and Jeroslow's theorem that ‘each integer programming value function is a Gomory function.’
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Journal of solution chemistry 14 (1985), S. 41-48 
    ISSN: 1572-8927
    Keywords: Solute association ; ring dimers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A 57.8 molal solution of orthophosphoric acid (85% w/w) has been studied by the wide angle X-ray scattering method. Both the ARDF and the intensity curve are consistent with a hydrogen-bonded ring structure for the dimeric (H3PO4)2.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Zeitschrift für angewandte Mathematik und Physik 39 (1988), S. 1-12 
    ISSN: 1420-9039
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Description / Table of Contents: Zusammenfassung Es wird die schallnahe Sperrströmung um einen zweidimensionalen Flügel in einem weiten Windkanal analysiert. Asymptotische Reihenentwicklungen werden in der transsonischen Ähnlich-KeitsvariablenK T im inneren Bereich in der Nähe des Körpers und im äußeren Bereich nahe der Wandung konstruiert und verglichen. Die innere Reihenentwicklung besteht aus freier Schallströmung und einem Korrektionsglied. Die äußere Reihenentwicklung steht für das Zusammentreffen der Schallinie und der Grenzcharacteristik an der Wandung. Es werden die Größe des Korrektionsgliedes zur freien Schallströmung am Körper, als auch die Abhängigkeit der Machschen Zahl der freien Strömung von der Höhe des Windkanals bestimmt. Ein Randwertproblem wird formuliert um die Korrektur zur freien Schallströmung zu bestimmen.
    Notes: Summary Choked transonic flow about a thin two-dimensional airfoil in a wide wind tunnel is analyzed. Asymptotic expansions are constructed in terms of the transonic similarity variableK T as KT→0 (and the tunnel height→∞), in an inner region, “near” the body, and in an outer region, near the walls, and are matched. The inner expansion consists of sonic free flow plus a correction. The outer expansion accounts for the meeting of the sonic line and the limit characteristic at the wall. The magnitude of the correction to sonic free flight at the body as well as the dependence of the choking Mach number on the wind tunnel height are determined. A boundary value problem is formulated to determine the correction to the free flight sonic flow.
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  • 5
    ISSN: 1572-879X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The direct gas phase electrochemical reduction of nitrogen to ammonia is reported at ruthenium/solid polymer electrolyte interface using cells of the general configuration N2, Ru/Nafion417/Pt, Ar(90%), H2(10%). The Faradaic efficiency for reducing nitrogen to ammonia was found to be 0.0015% at a current density of 3.12 mA/cm2 corresponding to 1.75 × 10−9 moles cm−2h−1 on a 9.65 cm2 electrode. Substitution of N2 by Ar in the cathode chamber of these cells gave no detectable ammonia, suggesting introduced N2 as the source used during NH3 synthesis.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Entomologia experimentalis et applicata 43 (1987), S. 227-235 
    ISSN: 1570-7458
    Keywords: Brown planthopper ; Nilaparvata lugens ; rice ; feeding behaviour ; resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé Le comportement alimentaire de Nilaparvata lugens sur variétés de riz, sensible (IR22), partiellement résistante (IR46) et fortement résistante (IR62), a été contrôlé avec une méthode associant la vidéo à l'observation. N. lugens faisait des piqûres plus fréquentes et plus brèves sur IR46 et IR62, que sur la variété sensible. La production de miellat était significativement plus faible sur les variétés résistantes, bien que les gains de poids des insectes aient été les mêmes en 24 h sur IR46 et IR22, les deux étant significativement supérieurs à celui sur IR62. La croissance de la population, l'indice de croissance et le taux de dégâts étaient tous plus faibles sur IR62, ce qui révèle une antibiose et/ou une absence de préférence. Quand la contamination des IR46 a au lieu au stade semis, la croissance de population, l'indice de croissance et le taux de dégâts étaient semblables à ceux de la variété sensible IR22. Quand la contamination avait lieu à un stade ultérieur, le laux de dégâts révélait un niveau modéré de résistance bien qu'une certaine croissance de population se soit maintenue, ce qui révèle antibiose et tolérance. Après exploration de la surface des feuilles des deux variétés résistantes, N. lugens sondait moins fréquemment que sur IR22, ce qui laisse présumer un facteur de résistance associé aux cires superficielles de ces variétés.
    Notes: Abstract The feeding behaviour of Nilaparavata lugens was monitored on three rice varieties showing different levels of resistance in the Philippines, using a video-assisted observation method. N. lugens made more frequent, shorter probes on the moderately resistant IR46 and resistant IR62 rice varieties than on the susceptible IR22. Honeydew production was significantly lower on the resistant varieties though insect weight gains in 24 h were similar on IR46 and IR22, both being significantly greater than on the highly resistant variety. Population development, growth index and damage ratings were low on IR62 indicating antibiosis and/or non preference. When IR46 plants were infested as seedlings population increase, growth index and damage ratings were similar to those on the susceptible IR22. When infested at a later stage of plant growth the damage rating showed a moderate level of resistance though some population development was maintained, indicating antibiosis and tolerance. N. lugens started probing less frequently after surface exploration on both resistant varieties than on IR22 suggesting the presence of a resistance factor associated with the surface waxes of these varieties.
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  • 7
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary A co-culture, consisting of five defined bacteria [e.g., T. Thurnheer, T. Köhler, A. M. Cook, and T. Leisinger: J Gen Microbiol 132:1215–1220], was able to degrade at least seven substituted benzenesulfonic acids in continuous culture. HPLC, total organic carbon analyses and colourimetric analyses showed that the sulfonated compounds could be completely degraded to biomass, SO 4 2- , NH 4 + and CO2. The maximum observed degradation rate was 138 mg of C/h·1. The five organisms were Alcaligenes sp. strain 0–1 (substrates benzenesulfonic acid, 4-methylbenzenesulfonic acid and 2-aminobenzenesulfonic acid), two Pseudomonas spp., strains T-2 (substrates 4-methylbenzenesulfonic acid and 4-sulfobenzoic acid) and PSB-4 (substrate 4-sulfobenzoic acid) and two unidentified rods, strains M-1 (substrates benzenesulfonic acid, 4-methylbenzenesulfonic acid and 3-aminobenzenesulfonic acid) and S-1 (substrates 4-aminobenzenesulfonic acid and 4-hydroxybenzenesulfonic acid). The system was operated for over 18 months with five sulfonates, and no competition was detected amongst the four organisms present, because all organisms were still present (100% of the population after 7 months, 55% after 18 months). Many bacteria isolated from the continuous culture after 18 months showed substrate ranges different from those of the original strains. The most common occurrence (33% of the population) was the appearance of organisms which could degrade 2-aminobenzenesulfonic acid and 4-sulfobenzoic acid. Several cases of the loss of a character were seen but only rarely (1%) was a net gain of characters observed. After 30 months, only two (of five) parents were present (35% of the population) and some isolates could utilize all seven substrates on solid media.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Formal aspects of computing 1 (1989), S. 147-171 
    ISSN: 1433-299X
    Keywords: Formal algebraic specification ; Larch ; User interface ; Apple MacintoshTM Toolbox
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract The Macintosh™ Toolbox is a collection of resources, stored in ROM, of use to software developers building user interface components. This paper documents an attempt to specify one part of the Toolbox: namely the data types and routines for event-handling. The chief objective of the paper is to illustrate an approach to building a formal specification in which, starting from simple structures, the final specification is arrived at by a process of successive modifications, generalisations, instantiations and translations. The paper also constitutes an example of the Larch algebraic style, as well as the two-tiered approach characteristic of the Larch family of specification languages.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Journal of paleolimnology 1 (1988), S. 71-73 
    ISSN: 1573-0417
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Origins of life and evolution of the biospheres 15 (1985), S. 77-88 
    ISSN: 1573-0875
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract The effect of adsorbed ions and pH on the adsorption of several purine and pyrimidine nucleotides on montmorillonite was studied. The cations used to prepare homoionic montmorillonite were Na+, Mn2+, Fe3+, Co2+, Ni2+, Cu2+, and Zn2+. The nucleotides studied were 5′-, 3′-, and 2′-AMP, and 5′-CMP in the pH range 2 through 12. The results show that preferential adsorption amongst nucleotides and similar molecules is dependent upon pH and the nature of the substituted metal cation in the clay. At neutral pH, it was observed that 5′-AMP was more strongly adsorbed than 2′-AMP, 3′-AMP, and 5′-CMP. Cu2+ and Zn2+ clays showed enhanced adsorption of 5′-AMP compared to the other cation clays studied in the pH range 4–8. Below pH 4, the adsorption is attributed to cation and anion exchange adsorption mechanisms; above pH 4, anion exchange may also occur, but the adsorption (when it occurs) likely depends on a complexation mechanism occurring between metal cation in the clay exchange site and the biomolecule. It is thus proposed that homoionic clays may have played a significant role in the concentration mechanism of biomonomers in the prebiotic environment, a prerequisite step necessary for the formation of biopolymers in the remaining steps leading to the origin of life.
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