Behind every purposeful movement lies a pattern of control and activation. One of the most fundamental movement patterns for humans is that of walking or gait. This study was conducted to further understand gait development of toddlers. This developmental stage was investigated with 13 healthy normal toddlers (11 girls and 2 boys) between the ages of 10 and 24 months who were autonomous walkers of less than a year. All toddlers walked across two force plates (ANITI) touching only with the right foot and were filmed with three (Panasonic) video cameras. Support moments as well as hip, knee and ankle joint moments and powers were calculated for between 6 and 14 steps per toddler. Joint moments and powers were normalized to percent of stride and body mass and were examined across subjects to observe developmental changes over the first year of walking. As well, the toddler joint moments and powers were compared to that of adult slow walking reported by Winter (1991). The data suggests two things: (1) toddler joint moments and joint powers develop over the first year of walking in a distal to proximal fashion and (2) toddler support moments, joint moments and joint powers are different from that of adults.

Goldfish are able to drastically change their gill morphology by forming an interlamellar cell mass (ILCM) when acclimated to temperatures below 15 ° C. This morphological change is reversed when the fish is exposed to hypoxia or an increase in temperature. The main goal of this thesis was to investigate how the presence of the ILCM affects the transfer and sensing of respiratory gases as well as to identify the cues that trigger gill remodelling. Using an extracorporeal blood shunt to measure blood gases, I show that the presence of the ILCM does not impede O2 uptake under normoxic or hypoxic conditions but presents an additional diffusion limitation to CO 2 excretion owing to chemical equilibrium constraints. Hypoxemia induced by carbon monoxide or phenylhydrazine elicited a decrease in the ILCM in cold (70 C) acclimated goldfish while exposure to hyperoxia partially prevented the reduction of the ILCM during a temperature increase.

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