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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Behavior genetics 11 (1981), S. 415-423 
    ISSN: 1573-3297
    Keywords: Drosophila pseudoobscura ; Drosophila persimilis ; drosophila mazes ; maze running behavior ; geotaxis ; genotype-environment interactions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Psychology
    Notes: Abstract Wild-type and mutant strains ofDrosophila pseudoobscura andD. persimilis were studied for the following maze running activities: frequency of maze completion, rate of progress through the maze, and geotaxis. It was found that these three components of maze behavior were affected to some extent by sex, strain, and species. The significance of these findings in assessing genotype-environment interactions inDrosophila maze studies is discussed.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-3297
    Keywords: Drosophila pseudoobscura ; Drosophila persimilis ; phototaxis ; habitat preference ; phenotypic plasticity ; genotypic variation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Psychology
    Notes: Abstract The photobehavior of a sympatric assemblage ofDrosophila pseudoobscura andD. persimilis from California was examined over a 13-month period. During that time, certain aspects of the behavior remained constant (e.g., the mean resting photoresponse), while other aspects changed (e.g., the level of genotypic variation of the resting photoresponse ofD. persimilis). The data support the contention of Rockwellet al. [Rockwell, R. F., Cooke, F., and Harmsen, R. (1975).Behav. Genet. 5:189–202] that genotypic variation and phenotypic plasticity are central features of photobehavior in natural populations of these species. The evolutionary importance of such genotypic variation and phenotypic plasticity is discussed.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1831-1835 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Average polymer segment densities and thermodynamic properties of polymer adsorbed at liquid-solid interfaces were computed by extension of the polymer adsorption theory of Forsman and Hughes. Expressions were derived for the total free energy of adsorbed polymer chains by using the Flory-Huggins theory to represent free energy of mixing. A square-well potential was used to represent segment-surface interaction, and configurational entropy was calculated from the probability density function for the radius of gyration of random-flight chains. For each specified amount of surface coverage the free energy of the adsorbed polymer was minimized by varying the density of segments normal to the adsorbing surface and using a modified gradient search algorithm on a digital computer. Two different segment densities were considered, and they both gave qualitatively the same results. The two densities were (1) the sum of two Gaussian distributions and (2) a two-step density distribution. Isotherms were then calculated by equating the partial molal free energy of polymer at the surface to that of polymer in bulk solution for each specified amount of surface coverage. The results showed that for the initial region of the isotherms the distribution of polymer segments normal to the surface consisted of a high-density layer adjacent to the surface and a low-density “tail” extending far out into the solution. At higher amounts of adsorbed polymer, i.e., in the general concentration range of the pseudo-plateau, the tail of the polymer density distribution was predicted to thicken, and a single Gaussian distribution best described the segment density. Predicted adsorptions were in good agreement with reported experimental values.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1573-3297
    Keywords: Drosophila pseudoobscura ; Drosophila persimilis ; phototaxis ; intrapopulation variation ; behavior
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Psychology
    Notes: Abstract The photoresponses of natural populations ofD. pseudoobscura andD. persimilis, occurring sympatrically, are measured in two environmental conditions (“at rest” and “disturbed”). Comparisons of the responses, intraspecifically and interspecifically, lead to the following conclusions. These must be considered within the confines of the operational nature of the measurement of laboratory photoresponses. (1) Within each species population, significant nonenvironmental differentiation has been allowed or produced by selection in the “at rest” photoresponse. No significant nonenvironmental differentiation is found in the photoresponse measured in a disturbed condition. (2) Within each species population, a higher mean “disturbed” photoresponse has been favored. The intensities or patterns of selection acting on these two photoresponses have differed such that more intrapopulation differentiation has been allowed or produced in the “at rest” photoresponse. (3) A higher mean photoresponse has been favored inD. persimilis for both conditions. The intensities or patterns of selection acting between these two species populations on the “at rest” photoresponse have differed such that more intrapopulation differentiation has been allowed or produced inD. persimilis. (4) Comparisons of this study with one on intraspecific and interspecific differentiaiton in wing length lead to the conclusion that the selective differences inferred above have acted at a level more specifically attuned to photobehavior.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 10 (1972), S. 607-614 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A number of empirical equations are presented that are good approximations to computed probability density functions of the one, two and three-dimentional radii of gyration of linear random-flight chains. Equations are given that are in good agreement with the distributions over the range of the radii of most physical interest. Alternative equations are presented that give especially good fit for small values of the one and two-di-mensional radii.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1847-1864 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Average polymer segment densities and thermodynamic properties of polymer adsorbed at liquid-solid interfaces were computed by extension of the polymer adsorption theory of Forsman and Hughes. Expressions were derived for the total free energy of adsorbed polymer chains by using the Flory-Huggins theory to represent free energy of mixing. A square-well potential was used to represent segment-surface interaction, and configurational entropy was calculated from the probability density function for the radius of gyration of random-flight chains. For each specified amount of surface coverage the free energy of the adsorbed polymer was minimized by varying the density of segments normal to the adsorbing surface and using a modified gradient search algorithm on a digital computer. Two different segment densities were considered, and they both gave qualitatively the same results. The two densities were (1) the sum of two Gaussian distributions and (2) a two-step density distribution. Isotherms were then calculated by equating the partial molal free energy of polymer at the surface to that of polymer in bulk solution for each specified amount of surface coverage. The results showed that for the initial region of the isotherms the distribution of polymer segments normal to the surface consisted of a high-density layer adjacent to the surface and a low-density “tail” extending far out into the solution. At higher amounts of adsorbed polymer, i.e., in the general concentration range of the pseudo-plateau, the tail of the polymer density distribution was predicted to thicken, and a single Gaussian distribution best described the segment density. Predicted adsorptions were in good agreement with reported experimental values.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 15 (1977), S. 2185-2199 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Biaxial and uniaxial tensile stress relaxation tests were made on square sheet specimens of styrene butadiene rubber (SBR), mounted in a universal biaxial tester within a temperature-controlled box, with the object of studying the effect of temperature on the strain energy function. The stress relaxation responses, usually for times up to 10 min, were obtained for various degrees of biaxiality, various extension ratios, and various temperatures within the limits of +25 to -45°C. The results indicated that if the Valanis-Landel representation of the strain energy function \documentclass{article}\pagestyle{empty}\begin{document}$ W = \sum\nolimits_{i = 1}^3 {w\left( {\lambda _i } \right)} $\end{document} is adopted, then time and strain are factorizable over the indicated temperature range, with time and temperature being related in the usual fashion. That is, changing the temperature does not affect the form of w(λi) but only that of G(t/αT), the temperature-dependent relaxation modulus, aT being the regular Williams-Landel-Ferry (WLF) shift factor. The results verify the Valanis-Landel theory for various combinations of biaxiality
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 10 (1972), S. 2041-2049 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The biaxial response, in combined torsion and tension or compression, of a highly crosslinked polyurethane elastomer has been measured at room temperature under equilibrium conditions with the Becker-Landel torsion-tension tester. Cylindrical specimens of four different aspect ratios were studied. Axial strains ranged from -33% to + 17%, and twists from 0 to 0.83 radians/cm. End effects were avoided by measuring both strains in the gage length at the center of the specimen. A small error in the twist parameter, probably arising from slight misalignment of the instrument, was unresolved. Within this error the normal forces and moments of all the specimens conformed to the neohookean (Mooney-Rivlin with C2 = 0) stored energy function for incompressible materials, and the moduli measured in extension and compression were equal.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 15 (1977), S. 1081-1095 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of acetylene-terminated phenylquinoxaline oligomers have been prepared which cure by addition, without the evolution of volatiles. The synthesis utilized the novel terminal acetylene end-capping reagent, 3-(3,4-diaminophenoxy)phenylacetylene. The end-capped oligomers were soluble (20-30%) in low-boiling organic solvents and exhibited a high degree of flow at their softening temperatures. Thermal analytical data obtained on the oligomers indicated initial softening in the vicinity of 160°C and a strong polymerization exotherm reaching a maximum at 274°C. Cured samples (8 hr at 280°C) exhibited Tg values of approximately 320°C. Mass spectrometry-thermogravimetric analysis of the polymers demonstrated that no volatiles were emitted during cure, and that decomposition of the resins initiated at 465°C. Synthetic routes to the acetylene terminated phenylquinoxaline oligomers and the end-capping reagent are discussed as well as the physical properties of the oligomer and cured system.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 4 (1983), S. 276-282 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A scheme is presented that enables photographic representation of the (two-dimensional) surfaces of (three-dimensional) molecular orbitals and electron density functions. The algorithm has been implemented by a program which is completely general and computationally efficient.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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