Invalid and irrelevant comparisons: apples or oranges?
Explore the source record for details and available documents.
Acetates↗
Biomedical subjects
Kevin Carter
Publications and source records attributed to Kevin Carter.
Response surface optimization for joint contact model evaluation.
When optimization is used to evaluate a joint contact model's ability to reproduce experimental measurements, the high computational cost of repeated contact analysis can be a limiting factor. This paper presents a computationally-efficient response surface optimization methodology to address this limitation. Quadratic response surfaces were fit to contact quantities (contact force, maximum pressure, average pressure, and contact area) predicted by a discrete element contact model of the tibiofemoral joint for various combinations of material modulus and relative bone pose (i.e., position and orientation). The response surfaces were then used as surrogates for costly contact analyses in optimizations that minimized differences between measured and predicted contact quantities. The methodology was evaluated theoretically using six sets of synthetic (i.e., computer-generated) contact data, and practically using one set of experimental contact data. For the synthetic cases, the response surface optimizations recovered all contact quantities to within 3.4% error. For the experimental case, they matched all contact quantities to within 6.3% error except for maximum contact pressure, which was in error by up to 50%. Response surface optimization provides rapid evaluation of joint contact models within a limited range of relative bone poses and can help identify potential weaknesses in contact model formulation and/or experimental data quality.
Bone Screws↗
Automated quantification of dental plaque accumulation using digital imaging.
OBJECTIVES: Most dental plaque indices have a subjective component due to investigator interpretation. To assess the accumulation of plaque on teeth, a fully automated method was developed based on digital imaging of methylene blue (1% (w)/(v)) disclosed plaque. METHODS: Intra-oral colour images of disclosed plaque from 25 individuals were coded into hue, saturation and intensity colour space. Unequivocal areas of clean teeth, plaque and clean gingiva were sampled to determine the typical values of hue, saturation and intensity of light. RESULTS: Discriminant analysis showed that the success rate for classification of the pixels as plaque and non-plaque was 87.3% based on saturation and intensity, and 98.7% for a classifier based on hue and intensity. Fisher's function coefficients were used to create classification boundaries in the colour space which would allow to automatically classify new images. CONCLUSIONS: This method has potential for automated and quantitative measurement screening of dental plaque that may be used to assess the efficacy of oral hygiene products and procedures.
Adult↗
The mGlu2/3 receptor agonist LY379268 injected into cortex or thalamus decreases neuronal injury in retrosplenial cortex produced by NMDA receptor antagonist MK-801: possible implications for psychosis.
The non-competitive NMDA receptor antagonists, including PCP (phencyclidine), ketamine, and MK-801 (dizocilpine) produce psychosis in humans and injure neurons in retrosplenial cortex in adult rodent brain. This study examined the effects of the metabotropic mGlu2/3 agonist LY379268 and antagonist LY341495 on cortical injury produced by systemic MK-801 (1 mg/kg i.p.) in adult female rats. Systemic injections of mGlu2/3 agonist LY379268, but not mGlu2/3 antagonist LY341495, decreased the injury in the retrosplenial cortex produced by systemic MK-801 as assessed by Hsp70 induction. Bilateral injections of LY379268, but not vehicle, into retrosplenial cortex or bilateral injections of LY379268 into anterior thalamus also decreased the injury in retrosplenial cortex produced by systemic MK-801. The data show that bilateral activation of mGlu2/3 glutamate receptors in cortex or anterior thalamus decreases the neuronal injury in retrosplenial cortex produced by systemic MK-801. Because antipsychotic medications decrease cortical injury produced by NMDA antagonists in rodents and decrease psychosis in humans, mGlu2/3 agonists that decrease cortical injury produced by NMDA antagonists in rodents might be evaluated for decreasing psychosis in people.
Amino Acids↗
Transforming growth factor-beta expression is significantly lower in hearts preserved with blood/insulin versus crystalloid cardioplegia.
The major cause of morbidity and mortality after cardiac transplantation is cardiac allograft vasculopathy (CAV). The purpose of this study was to examine the expression of markers of endothelial injury that may be affected by blood/insulin or crystalloid cardioplegia. After RNA-blot hybridization, the level of expression of tumor necrosis factor-alpha, transforming growth factor-beta (TGF-beta), intracellular adhesion molecule-1, platelet-endothelial cell adhesion molecule-1, endothelin-1, and E-selectin was increased in crystalloid cardioplegia as compared with normal and blood/insulin cardioplegia; TGF-beta was expressed at significantly lower levels in blood/insulin vs crystalloid cardioplegia (p < 0.05). Because increased expression of TGF-beta has been correlated with accelerated CAV, the use of blood/insulin cardioplegia may help to decrease the extent of endothelial damage and attenuate the progression of CAV.
Cardioplegic Solutions↗