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Digitale Medien

Ecology, feeding competition and social structure in baboons (1996)

Barton, R. A. ; Byrne, Richard W. ; Whiten, Andrew

Springer

Behavioral ecology and sociobiology 38 (1996), S. 321-329

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ISSN: 1432-0762

Schlagwort(e): Key words Ecology ; Competition ; Group size ; Baboons

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie

Notizen: Abstract Predictions of the model of van Schaik (1989) of female-bonding in primates are tested by systematically comparing the ecology, level of within-group contest competition for food (WGC), and patterns of social behaviour found in two contrasting baboon populations. Significant differences were found in food distribution (percentage of the diet from clumped sources), feeding supplant rates and grooming patterns. In accord with the model, the tendencies of females to affiliate and form coalitions with one another, and to be philopatric, were strongest where ecological conditions promoted WGC. Group fission in the population with strong WGC was “horizontal” with respect to female dominance rank, and associated with female-female aggression during a period of elevated feeding competition. In contrast, where WGC was low, females’ grooming was focused on adult males rather than other females. Recent evidence suggests that group fission here is initiated by males, tends to result in the formation of one-male groups, and is not related to feeding competition but to male-male competition for mates. An ecological model of baboon social structure is presented which incorporates the effects of female-female competition, male-male competition, and predation pressure. The model potentially accounts for wide variability in group size, group structure and social relationships within the genus Papio. Socio-ecological convergence between common baboons and hamadryas baboons, however, may be limited in some respects by phylogenetic inertia.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/s002650050248

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Digitale Medien

Structure and property development in poly(p-phenylene terephthalamide) during heat treatment under tension (1995)

Lee, K.-G. ; Barton, R. ; Schultz, J. M.

Bognor Regis [u.a.] : Wiley-Blackwell

Journal of Polymer Science Part B: Polymer Physics 33 (1995), S. 1-14

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ISSN: 0887-6266

Schlagwort(e): poly (p-phenylene terepthalamide) ; Kevlar® ; heat treatment ; structure development ; mechanical properties ; Chemistry ; Polymer and Materials Science

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie , Physik

Notizen: The evolution of several structural characteristics during isothermal heat treatment of poly(p-phenylene terephthalamide) was studied. In this work, heat treatment was interrupted after different treatment times, with the specimens immediately quenched to room temperature. These specimens were then characterized by tensile testing, wide- and small-angle x-ray scattering, and optical microscopy. Structural parameters obtained from these measurements relate to crystal perfection (via the paracrystalline axial distortion parameter), axial crystallite size, transverse crystallite size, degree of chain misorientation, and degree of pleating. Structural and mechanical parameters were then plotted against heat-treatment time to obtain kinetic isotherms for each parameter. The kinetics of the removal of chain misorientation parallels that of tensile modulus increase under all conditions. Of the other structural parameters, only the kinetics of pleat removal mimics that of modulus change, indicating that pleat removal is the effective cause of increased chain alignment and thereby of increased axial stiffness. ©1995 John Wiley & Sons, Inc.

Zusätzliches Material: 27 Ill.