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Biomedical subjects

R S Gross

Publications and source records attributed to R S Gross.

5 recordsLinked to original sources

Ratio scales of the reward values and punisher aversions of depressed undergraduates.

Two experiments (Ns = 116 and 154, respectively) tested theories that state that depressed people undervalue rewards or are overly averse to punishers. Rational zero-point scaling was used to obtain ratio scales of undergraduates' reward values and punisher aversions. As the theories predicted, depressed students consistently valued classmate praise about three- to six-tenths as highly as did nondepressed students; depressed females were 1.4 times more averse to all four punishers (classmate and professor criticism, incorrectness feedback, and monetary fine), while depressed males were 1.2 times more averse to the three intangible punishers. Contrary to the theories, depressed students consistently failed to undervalue the remaining three rewards (professor praise, money, and correctness feedback), and depressed males failed to be overly averse to a monetary fine. It was concluded that reward-value theories of depression received more narrow support than did the punisher-aversion theories. In addition, developmental theories of reward values were supported by the finding that studies from low social-status backgrounds valued the abstract rewards about seven-tenths as highly as did high status students.

Depressive Disorder

Femoral strain distribution and subsidence after physiological loading of a cementless canine femoral prosthesis: the effects of implant orientation, canal fill, and implant fit.

Twelve normal greyhound femora were divided into three groups. In group one, femoral stems were placed in neutral position with maximal fill. Group two had undersized femoral stems placed in neutral position. Group three had undersized femoral stems placed in varus position. Intact and implanted femora were loaded from 10 newtons (N) to 300 N in axial compression at a rate of 25 N/s for 10 replications. A strain gauge analysis showed that the strain distribution of all implanted femora were substantially different from intact femora, but femora with large implants placed in neutral position had the least amount of deviation from normal. An undersized stem in neutral position had significantly less compressive longitudinal strains along the proximomedial and proximocranial cortices. An undersized stem in varus position improved implant fit along the proximomedial and distolateral cortices, which resulted in increased tensile hoop strains. There were multiple significant correlations between the strain data and implantation variables (implant alignment, canal fill, and implant fit). Subsidence was significantly greater for the undersized implant in neutral position. There was not a difference in subsidence between the large neutral and varus groups. The most important variable that decreased subsidence was increased lateral implant fit (r = -0.86, P = .0003).

Animals

The effects of implant orientation, canal fill, and implant fit on femoral strain patterns and implant stability during catastrophic testing of a canine cementless femoral prosthesis.

Cementless femoral stems were placed into 12 normal greyhound femora. The implanted femora were divided into three groups by stem orientation and implant size and loaded in axial compression at a rate of 25 newtons (N) per second until failure. Rosette strain gauges were used to measure femoral principal strains at 500 N, 1,000 N, 1,500 N, and at maximum load. During maximum load, varus orientation of the femoral stem had significantly higher tensile hoop strains in the proximomedial cortex, whereas neutral orientation had higher tensile hoop strains along the cranial cortex. Femoral fractures occurred in these areas of peak tensile strain. There was no difference in maximum load between groups, therefore varus orientation did not predispose to fracture. Maximizing canal fill and implant fit increased implant stability.

Animals