Abstract: Demand curves were generated for five domestic hens under progressive-ratio 5 schedules of food delivery and under fixed-ratio schedules of food delivery that began at fixed-ratio 5 and were incremented by 5 each session. All sessions ended after 10 consecutive minutes without a response. Although response rates at a given ratio were higher under the progressive-ratio schedule, all hens completed higher ratios under the fixed-ratio schedule. Similar, but not identical, demand curves were generated under progressive-ratio and fixed-ratio schedules. Under both schedules, consumption (reinforcers earned) decreased as cost (ratio size) increased. Data generally were well described by an equation in which elasticity of demand is constant, although an equation in which elasticity could vary accounted for slightly more of the variance.

Abstract: Thirty horses were filmed with a panning camera operating at 50 frames/s as they jumped over a 1.20 x 1.20 m fence. The markers of 9 joints on the horse and 7 joints on the rider were tracked in 2D with the TrackEye system. The centre of gravity and moment of inertia of each segment were calculated using a geometric algorithm and a cylindric model, respectively. The kinetic moment of each part of the horse was calculated after filtering, and resampling of data. This method showed the relative contribution of each body segment to the body overall rotation during the take-off, jump and landing phases. It was found that the trunk, hindlimbs and head-neck had the greatest influence. The coordination between the motion of the body segments allowed the horse to control its angular speed of rotation over the fence. This remained nearly constant during the airborne phase (120 +/- 5 degrees/s). During the airborne phase, the kinetic moment was constant because its value was equal to the moment of the external forces (722 +/- 125 kg x m2/s).

Abstract: OBJECTIVE: To describe clinical findings, ultrasonographic features and outcome of injury to the branches of insertion of the superficial digital flexor (SDF) tendon in horses. DESIGN: Retrospective study of 14 cases. PROCEDURE: Fourteen Thoroughbred horses with tendonitis affecting the branches of insertion of the SDF tendon were examined for lameness, location and amount of swelling, and the presence of other musculoskeletal abnormalities. The flexor tendons were assessed by ultrasonographic examination, and recommendations were made for management of the cases. Outcome was assessed by re-examination of some horses, direct communication with the owner or trainer, and examination of race records. RESULTS: The lateral SDF branch was affected in 10 horses; the medial branch in three, and both branches in one horse. Two horses had concurrent injuries to the SDF tendon in the metacarpal region of the contralateral limb. Ultrasonographic findings included swelling of the affected SDF branch, peritendinous fluid accumulation, disruption of normal fibre alignment on sagittal scan, and variable loss of echogenicity. As healing occurred, there was return of normal echogenicity, but normal fibre alignment did not return completely and apparent adhesions formed between the affected SDF branch and adjacent structures. Seven of 10 horses which returned to their previous use were able to compete without further tendon injury. Recurrence of injury occurred in one case, and another two horses developed tendonitis in the metacarpal region. One horse was retired from racing but was able to compete at dressage without recurrence of injury. Two horses were retired for breeding without returning to training, and one horse was sold and lost to follow up but did not race. CONCLUSION: The prognosis is fair for return to previous use following injury to the branches of insertion of the SDF tendon in athletic horses.

Abstract: The behavior of nine lowland gorillas (Gorilla gorilla gorilla) living in three social groups at Zoo Atlanta was compared in an indoor holding area versus an outdoor exhibit. Focal animal data were collected for each animal during 15 min observation sessions, alternating between indoors and outdoors. A variety of solitary and social behaviors differed in the two conditions. All individual and social behaviors that showed a difference, except eating, occurred more indoors than outdoors. These included aggressive displays, reclining, self manipulation, and social examination of others. Additionally, the gorillas spent more time closer together in the indoor condition. A variety of other behaviors measured did not change between the two environments. There was a clear effect on behavior of the different housing conditions in which the gorillas were kept. It is suggested that the differences in aggressive behavior may be related to environmental complexity. It is further suggested that zoos should be aware that differences in behavior reported by caretaking staff, researchers and visitors may be a reflection of the differing environmental circumstances in which the animals are observed.