No abstract

No abstract

Foot orthotics have proven to be an effective means of reducing clinical symptoms in the lower limb. Kinematic studies of runners have substantiated these findings by showing significant changes in a number of parameters describing foot function. This study examines the effect of foot orthotics during the loading response of walking, the period of stance when angular movements and positions of the calcaneus typically attain peak values. Twenty subjects exhibiting a minimum of 5 calcaneal eversion in static stance volunteered for this study. A musculoskeletal examination of the lower limb was performed on all subjects and rigid orthotics were fabricated based upon the findings. All subjects participated in both the orthotic and no-orthotic treatment conditions. A VlCON three-dimensional motion analysis system with a force platform was used to collect data. A MANOVA procedure was used to perform statistical analysis on the multiple dependent variables. Results showed significant changes in the following variables: 1) maximum calcaneal and calcaneal eversion angles, 2) total rearfoot movement, 3) height of the ankle joint center when both the maximum calcaneal angles occurred, 4) minimum height of the ankle joint center, 5) mediolateral lever arm of the point of application of the ground reaction force when both the maximum calcaneal angles occurred, 6) maximum eversion moment due to ground reaction, 7) maximum calcaneal and calcaneal eversion angular velocity, and 8) maximum calcaneal eversion and tibia vara angular acceleration. J Orthop Sports Phys Ther 1990;11(7):301-312.

No abstract

Future discoveries of copper resources in the richly endowed porphyry copper belts of northern Chile are likely to occur in areas covered by post-mineral sedimentary and volcanic rock. Most of northern Chile is within a region of interior drainage that has existed since at least mid-Tertiary time when many of the porphyry copper deposits were being uplifted, eroded and supergene enriched. This setting, combined with accumulation of metal-enriched material eroded from the tops of porphyry copper deposits, has produced regions with high geochemical background and geochemically complex post-mineral cover that includes alluvium, lake and playa sediments, evaporites, aeolian material, ignimbrites and volcanic ash. In addition, the climate changed from semi-arid to hyper-arid in mid-Miocene time, creating a surface environment that is saline and slightly alkaline. The geochemical expression of the Chimborazo porphyry copper deposit in northern Chile was studied in detail using the following wet chemical extraction methods: 4-acid (HF-based), aqua regia, bulk cyanide leach, hot hydroxylamine hydrochloride, cold hydroxylamine hydrochloride, enzyme leach and de-ionized water. Limitations affecting several partial extraction methods include poor data quality, lack of pH control, re-adsorption, and the formation of colloids in the leachate. Experimentation with leach time and buffering capacity improved the robustness of some of the methods. Mechanical dispersion is the dominant secondary process in this region although chemical dispersion does occur laterally on a regional scale and vertically on a local scale. Vertical chemical dispersion is associated with dilatancy pumping of metalliferous groundwater along fractures. Supercedency, a process whereby the geochemical fingerprint of transported material is inherited from the underlying material, may have also played a role in the strong signature seen at Chimborazo.