Thomas Morrison

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STUDY DESIGN This is a retrospective review of 150 C2 pedicle screw placements. Candidates had their C2 pedicle morphology assessed through three-dimensional imaging, including preoperative image guidance. After surgery, the patients were serially CT scanned. Follow-up, with fusion assessment, ranged from 1 to 12 years. OBJECTIVE We will show that an open(More)
Metformin is a commonly used anti-diabetic but whether its mechanism involves action on the insulin receptor or on downstream events is still controversial. With a time course that was slow compared with insulin action, metformin increased tyrosine phosphorylation of the regulatory domain of the insulin receptor (specifically, tyrosine residues 1150 and(More)
OBJECT The occipital condyle has never been studied as a viable structure that could permit bone purchase by fixation devices for occipitocervical fusion. The authors propose occipital condyle screw placement as a possible alternative to conventional occipitocervical fixation techniques. METHODS Six adult cadaver heads (12 total occipital condyles) were(More)
Tree size distributions are the outcome of demographic processes and disturbance events, and size distribution analysis provides a useful tool for understanding pattern and process in tree population dynamics. Demographic bottleneck mechanisms such as fire “traps” are important for driving tree cover dynamics in savanna systems, and bottlenecks might be(More)
Studies have been carried out on the derivation of a typical bacterium from a pleuropneumonia-like organism (PPLO) of human urethral origin.Wittler et al. (1956) had previously described the reversion of this PPLO to aCorynebacterium sp. during tissue culture passage. Two general procedures were developed which promote a low rate of reversion in cell-free(More)
Tree recruitment in savannas proceeds in multiple stages characterized by successive filters occurring at the seed and seedling stages. The “demographic bottleneck” hypothesis suggests that such filters ultimately restrict tree density and prevent trees from dominating grasses in savannas, but many of the demographic transitions underlying this assumption(More)
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