Features of the Visuomotor Tracking Skill Formation Using Isometric Regulatory Organs in Orthopedic Patients at Different Stages after Elimination of Asymmetry in Lower Extremity Length

In orthopedic patients, the formation of the motor skill of rapid and precise reproduction of an effort by the anterolateral muscles of the shin of the elongated extremity was significantly decelerated as compared to the intact one when tested at 5–50% of the maximum muscular force of the intact extremity. A correlation was observed between the tracking square error, which is an index of precision of instrumental motor reactions, and the dynamic activation indices (the ratios between the electromyogram integrals and the force momentum impulse), which characterize energy expenses, and was assumed to reflect specific optimization of sensorimotor reactions at different power loadings. Both with the elongated and the intact extremities, the interactive search for and fixation of the optimal motor program was most effective in a certain range of muscular loading. The results can serve as a basis for choosing specific rehabilitation programs for orthopedic patients.__________Translated from Fiziologiya Cheloveka, Vol. 31, No. 4, 2005, pp. 70–80.Original Russian Text Copyright © 2005 by Shein, Krivoruchko, Saifutdinov.     

Safer sex with feeding females: sexual conflict in a cannibalistic spider

Mating strategies are to a large degree shaped by conflictsbetween the sexes, causing a rapid antagonistic coevolutionof traits involved in reproduction. The view that sexual cannibalismrepresents a form of sexual conflict leads to the predictionof male traits that facilitate escape from cannibalistic females.A variety of traits have been suggested to serve this functionin spiders, where sexual cannibalism is comparatively common.Empirical evidence, however, is virtually absent. Here we showexperimentally that opportunistic mating with feeding females,which has been reported from several species of orb-weavingspiders, greatly reduces the risk of cannibalism and injuryfor males in the spider Nephila fenestrata. This has directconsequences for a male's fertilization success because survivingmales can reduce the female's remating probability by guardingher against rivals. Although copulation with previously matedfemales sometimes appears to be mechanically impossible, secondmales that do copulate can expect to fertilize on average 64%of a female's eggs. Our results support the view that opportunisticmating may have evolved as a male tactic in a context of sexualconflict over sexual cannibalism.