Abstract: Equilibrium, stopped flow, and temperature-jump spectrophotometry have been used to identify processes in the unfolding of ferricytochrome c in acidic aqueous solutions. A relaxation occurring in approximately 100 microseconds involves perturbation of a spin-equilibrium between two folded conformers of the protein with methionine-80 coordinated or dissociated from the heme iron. The protein unfolds more slowly, in milliseconds, with dissociation and protonation of histidine-18. These two transitions appear cooperative in equilibrium measurements at low (0.01 M) ionic strength, but are separated at higher (0.10 M) ionic strength. They are resolved under both conditions in the dynamic measurements. The spin-equilibrium description permits a unified explanation of a number of properties of ferricytochrome c in acidic aqueous solutions.

Abstract: Herring gulls drop hard-shelled mollusks and hermit crab-inhabited molluskan prey in order to break the shells and gain access to the edible interior. A field study of predatory shell dropping on Cape Cod, Massachusetts, U.S.A. showed that the gulls usually drop the same shell repeatedly, orient directly to dropping sites that are invisible from the point at which the mollusks are captured, drop preferentially on hard surfaces, adjust dropping heights to suit the area and elasticity of the substrate, orient directly into the wind while dropping, sever the large defensive cheliped of hermit crabs before consumption, and rinse prey that is difficult to swallow. Proficiency in prey dropping is acquired through dropping objects in play, trial-and-error learning, and perhaps, observation learning.
Observable attributes of predatory shell-dropping support inferences that the gulls are capable of extended concentration, purposefulness, mental representation of spatially and temporally displaced environmental features, cognitive mapping, cognitive modeling, selectivity, and strategy formation. Identical cognitive processes have been inferred to underlie the most sophisticated forms of chimpanzee tool-use.
Advanced cognitive capacities are not restricted to chimpanzees and other pongids, and are not associated uniquely with tool use. The chimpocentric bias should be abandoned, and reconstructions of the evolution of intelligence should be modified accordingly.

Abstract: The biomechanics of tendon healing was investigated with unsutured rat achilles tendons. After two, three, and four weeks of healing tensile parameters were assayed with a bone-muscle-tendon-bone preparation elongated to failure at a controlled physiological strain rate. In the third week of healing, stiffness, strength, and energy absorbing capacity all increased approximately 50%. These changes correlated with early fibroplasia. In the fourth week of healing, strength, energy absorbing capacity and elongation to failure all increased relatively more than stiffness. Histologically, larger fibers with better longitudinal alignment developed during this period. At the end of four weeks the tendon's strength was approximately 25% of normal. To summarize, the return of stiffness in a healing tendon preparation correlated with the presence of fibroplasia and the return of other tensile parameters was a function of the amount and organization of the fibroplasia.