Although female Richardson’s ground squirrels (Urocitellus richardsonii) spend 80% of their lives sleeping and hibernating underground, studies on interactions and space-use have historically focused on the 20% of the time they spend aboveground. The type and frequency of aboveground interactions and degree of home-range overlap among female Richardson’s ground squirrels depend on their reproductive status and degree of kinship. The purpose of my study was to determine whether reproductive status and kinship influence underground sharing of space as well. I radio-collared 54 adult female Richardson’s ground squirrels (18 in 2008, 30 in 2009, and 6 in both years) of known maternal kinship in 5 spatially adjacent matrilines at a field site near Picture Butte, Alberta, Canada. Radio-collared females were located underground every evening after they retired and every morning before they emerged during both the 2008 and 2009 active seasons to determine sleep-site use and sleep-site sharing. The locations at which females were observed to retire in the evening (170 evenings) and emerge in the morning (141 mornings) in 2008 and 2009 were used to determine underground connections between surface entrances and underground sleep sites. Females commonly shared burrow systems, sleep sites, surface entrances, and underground connections after emergence from hibernation until mid-pregnancy and they shared again, though less frequently, after litters had been weaned, but they never shared underground features during lactation and hibernation. Close kin shared underground space more frequently than distant kin, and distant kin more frequently than non-kin. Variation in underground sharing of space over the active season and selective sharing with respect to kinship suggest that reproductive status and degree of kinship influence underground sharing. / xii, 121 leaves ; 29 cm

Although periglacial research in the high Drakensberg and Lesotho mountains has received growing interest amongst southern African geomorphologists, little detailed, quantitative information was available prior to this study. In an attempt to help overcome this deficit, a quantitative assessment on cryogenic landforms and processes operative in the high Drakensberg was undertaken. Morphological and sedimentological assessments of sorted patterned ground, non-sorted steps, thufur, blockstreams, stone-banked lobes, debris deposits and turf exfoliation landforms were undertaken. In addition, geomorphic process assessments in the field included the measurement of turf retreat at turf exfoliation sites, the determination of frost-heave mechanisms within wetlands and sediment mobilization along the Mashai Stream. Ground temperatures were recorded for thufur from 1993 to 1996. The environmental implications of some of the findings are discussed. Seasonal frost-induced sorted patterned ground emerges annually within a few weeks, demonstrating the effect of regular, diurnal freeze-thaw cycles during the winter months. It is found that the present climate is not conducive to maintaining or preserving miniature periglacial landforms below 3200m a.s.l. during the summer months. Large relict sorted circles, stone-banked lobes and blockstreams are the most conspicuous periglacial landforms in the high Drakensberg and are products of at least seasonally-frozen ground. It is suggested that debris deposits found within high Drakensberg cutbacks are possible indicators for marginal niche and cirque glaciation during the Late Pleistocene. It is demonstrated that in climatically marginal periglacial regions, the microtopographically controlled freezing processes may be of paramount importance in maintaining and modifying the cryogenic landforms that occur. Pronounced temperature differentials are found during the winter months, when thufur are frozen for several weeks and depressions remain predominantly unfrozen. It is suggested that such contemporary temperature differentials induce thermodynamic forces and ultimately ground heave at sites in the high Drakensberg. The pronounced seasonal weather patterns in the high Drakensberg have promoted a cycle of geomorphic process events that operate synergistically and initiate particular erosion landforms. However, cryogenic activity during the colder period is overwhelmed by water induced erosion processes during the summer months in the high Drakensberg. It is concluded that the high Drakensberg is currently a marginal periglacial region, but that periglacial conditions prevailed during both the Pleistocene and some Late Holocene Neoglacial events. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1997.

The thesis is divided into four parts; 1.The implantation of the blastodermic vesicle, 2.The method of amnion formation in Citillus, 3.The anatomy and foetal membranes of a 25 mm. embryo, 4.The brain of a 9 mm. foetus.

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Aim: The aim of this study was to investigate the differences between older and younger adults in the attenuation of impact during descent from a step. Strategies that have been implicated in reducing either the magnitude of vertical ground reaction force (vertical GRF) or the time taken to reach the maximum vertical GRF in the stepping leg were explored. Study Design: The study was an experimental, laboratory based, repeated measures design. Participants: Twenty participants took part in this exploratory study. Ten in the older group of 60-80 years, mean 65.3 (SD 5) years and ten in the younger age group of 20-30 years, mean 22.8 (SD 2.5) years. Main Measures: The vertical GRF and the time taken to reach maximum vertical GRF were measured to ascertain impact during step descent. Electromyography and kinematic variables were measured to determine the effect they may have on the impact. The variables measured were the maximum joint range of motion of the hip and knee during early stance in step descent. Surface electromyography from four lower limb muscles was recorded to ascertain the magnitude of muscle activity at impact. The relationship in an antero-posterior direction of the upper body and stepping leg at initial contact (IC) was also investigated. Results: There was a significant difference in both the amount of knee flexion and the amount of activity of the vastus lateralis muscle during impact between older and younger adults. Older adults had significantly less knee flexion during a step descent activity than younger adults (F(1,18)=5.48; p=.031).Older adults had significantly more vastus lateralis activity during a step descent activity than younger adults (F(1,18)=5.21; p=.035). Conclusions: Older and younger adults use different strategies in both muscle activation and joint range of motion around the knee of the leading leg during the step descent. Older adults used more vastus lateralis activity perhaps to increase stiffness in the knee, leading to a reduction in range of motion at impact. Although no change in vertical GRF was detected in this study, both of these strategies have the potential to increase the impact of a step and therefore cause jarring and possible damage. This study recruited healthy active older adults and differences in impact may be observed in an older or less active population, or in those with joint pathology such as osteoarthritis.

Aim: The aim of this study was to investigate the differences between older and younger adults in the attenuation of impact during descent from a step. Strategies that have been implicated in reducing either the magnitude of vertical ground reaction force (vertical GRF) or the time taken to reach the maximum vertical GRF in the stepping leg were explored. Study Design: The study was an experimental, laboratory based, repeated measures design. Participants: Twenty participants took part in this exploratory study. Ten in the older group of 60-80 years, mean 65.3 (SD 5) years and ten in the younger age group of 20-30 years, mean 22.8 (SD 2.5) years. Main Measures: The vertical GRF and the time taken to reach maximum vertical GRF were measured to ascertain impact during step descent. Electromyography and kinematic variables were measured to determine the effect they may have on the impact. The variables measured were the maximum joint range of motion of the hip and knee during early stance in step descent. Surface electromyography from four lower limb muscles was recorded to ascertain the magnitude of muscle activity at impact. The relationship in an antero-posterior direction of the upper body and stepping leg at initial contact (IC) was also investigated. Results: There was a significant difference in both the amount of knee flexion and the amount of activity of the vastus lateralis muscle during impact between older and younger adults. Older adults had significantly less knee flexion during a step descent activity than younger adults (F(1,18)=5.48; p=.031).Older adults had significantly more vastus lateralis activity during a step descent activity than younger adults (F(1,18)=5.21; p=.035). Conclusions: Older and younger adults use different strategies in both muscle activation and joint range of motion around the knee of the leading leg during the step descent. Older adults used more vastus lateralis activity perhaps to increase stiffness in the knee, leading to a reduction in range of motion at impact. Although no change in vertical GRF was detected in this study, both of these strategies have the potential to increase the impact of a step and therefore cause jarring and possible damage. This study recruited healthy active older adults and differences in impact may be observed in an older or less active population, or in those with joint pathology such as osteoarthritis.