No description available.

No description available.

No description available.

No description available.

The use of hot surface films for measuring skin friction is examined. It is shown that all existing theories, which neglect heat conduction within the substrate, are inadequate in predicting the variation of heat loss from the film with skin friction. A more physically realistic theory is presented which accounts for the conductive and convective heat transfer into the flow and also heat conduction within the substrate. This leads to a more general relationship between skin friction and heat loss from the film. Experiments conducted in flat plate laminar and turbulent boundary layer flow show that this relationship is more accurate than previous forms. The time and temperature dependence of the heat loss from the hot film are also explored theoretically and experi- mentally. The effect of surface misalignment of the film is shown to alter significantly the convective heat transfer. This effect is more pronounced in laminar flow than in turbulent flow. Using a glue-on hot film probe, calibrations relating the heat loss to skin friction were found to be different in laminar and turbulent flow. An experimental operating procedure for the use of hot surface films for measuring skin friction is proposed which significantly increases the accuracy of the technique.

The integument is the body organ interfacing between the internal and external environments of a lizard. This study explores aspects of its structure, texture, and coloration, relating them to survival strategies of horned lizards. The dermal chromatophore structure of Phrynosoma modestum is described. Color change depends on two cell types, melanophores and iridophores. This cellular arrangement may be typical of lizards utilizing color change for thermoregulation. Color pigment cells (xanthophores and erythrophores) function in pattern formation and background color matching. Experiments on the regulation of color change revealed that (1) -MSH is the prime skin darkening agent, (2) - and -adrenergic receptors also play a role in color change, and (3) temperature is a factor in in vitro and in vivo darkening and lightening responses. Apparently the primary role of color change is thermoregulation. Intraepidermal mechanoreceptors on dorsal body, limb, and head scales were studied, their ultrastructure is described, and their role in defense and survival is explored. The use of the integument for "rain-harvesting" of drinking water by P. cornutum is described, including stereotyped behavior, stereoscopic SEM examination of interscalar channels, experiments on capillary water flow, and an evaluation of micro-ornamentation. Comparisons are made with the putative use of the integument for the collection of rain, fog, or dew for drinking by Moloch and Phrynocephalus. A stereotypic behavior that utilizes positioning of occipital horns and dorsal scale armament is described and hypothesized to be an ophidian antipredator defense. Attacks by Onychomys torridus on P. cornutum and P. modestum were studied to further evaluate the role of occipital horns, dorsal scalation, and dermal collagen as antipredator defenses. Attack behaviors of the grasshopper mice and defense behaviors of the lizards are detailed. The use of color pattern, integumental structures, and mimetic behavior by P. modestum in avoidance of predator detection, through "stone-mimicry," is hypothesized and supported. Aspects of social communication in four species were studied. The importance of olfaction for intraspecific communication and lack of visual color signals is related to the need for chromatic crypticity in order to avoid detection by predators.

No description available.

No description available.

No description available.

No description available.