Handedness results from complementary hemispheric dominance, not global hemispheric dominance: Evidence from mechanically coupled bilateral movements

Two contrasting views of handedness can be described as 1) complementary dominance, in which each hemisphere is specialized for different aspects of motor control, and 2) global dominance, in which the hemisphere contralateral to the dominant arm is specialized for all aspects of motor control. The present study sought to determine which motor lateralization hypothesis best predicts motor performance during common bilateral task of stabilizing an object (e.g. bread) with one hand while applying forces to the object (e.g. slicing) using the other hand. We designed an experimental equivalent of this task, performed in a virtual environment with the unseen arms supported by frictionless air-sleds. The hands were connected by a spring, and the task was to maintain the position of one hand, while moving the other hand to a target. Thus, the reaching hand was required to take account of the spring load to make smooth and accurate trajectories, while the stabilizer hand was required to impede the spring load to keep a constant position. Right-handed subjects performed two task sessions (right hand reach and left hand stabilize; left hand reach and right hand stabilize) with the order of the sessions counterbalanced between groups. Our results indicate a hand by task-component interaction, such that the right hand showed straighter reaching performance while the left showed more stable holding performance. These findings provide support for the complementary dominance hypothesis and suggest that the specializations of each cerebral hemisphere for impedance and dynamic control mechanisms are expressed during bilateral interactive tasks

Effect of various fertilization on the microbiological activity of loamy soil

1-кратное удобрение глинистой почвы (образованной из тяжелой глины) высокими дозами разных удобрительных средств органического происхождения в небольщой степени усиливало интенсивность дыхания и дегидрогеназную активность почвы в первом и четвертом году полевого опыта. Рост протеолитической активности почвы проявлялся только вскоре по применении органического удобрения. Усиление нитрификации оказалось чувствительным показателем изменений в почве в зависимости от вида внесенного удобрения. Явный и отчетливый рост производительности этого процесса отметился в почве, удобренной навозом и осадком коммунальных сточных вод.Single application of large doses of various organic fertilizers on a brown soil developed from heavy loam resulted in a slight increase in the intensity of respiration and the dehydrogenase activity of the soil in the first and fourth years of the field experiment. An increase in the proteolytic activity of the soil became apparent only for a short period of time following the application of the organic fertilizer. Increased nitrification turned out to be a sensitive index of change occurring in the soil with respect to the type of fertilizer introduced. A distinct and lasting increase in the efficiency of the process was observed in the soil fertilized with manure and with a sewage sludge

Effect of various fertilization on the microbiological activity of sandy soil

Результаты 4-летних исследований показали дифференцированное воздействие вносимых органических удобрений на активность легкой (псевдоподзолистой, образованной из глинистого песка) почвы. Отчетливый рост интенсивности дыхания почвы - заметный в течение всего исследовательского периода - вызвало удобрение почвы высокими дозами осадка сточных вод и дефекационной грязи. Отрицательное влияние на общую микробиологическую активность легкой почвы вызвал ввод высоких доз жидкой жижи, а также кератино-коро-карбамидного гранулята. Дифференцированное удобрение почвы в небольшой степени повлияло на интенсивность процессов, связанных с минерализацией азота - протеолиза и аммонификации. Нитрификационную силу исследуемой почвы отчетливо увеличивало внесение высоких доз навоза, осадка сточных вод и дефекационной грязи. Ограничение интенсивности нитрификации отметилось зато в почве, в которую ввели высокую дозу кератино-коро-карбамидного гранулята.The results of the four-year study showed a differentiation in the effect of the organic fertilizers used on the activity of a light soil (pseudopodzolic soil developed from weakly loamy sand). A distinct increase in the intensity of soil respiration, notable throughout the period of the study, was caused by the introduction into the soil of large doses of sewage sludge and of defecation lime. The application of large doses of slurry, as well as of keratin-bark-urea granulate, had an unfavourable effect on the general microbiological activity of the light soil. Differentiated fertilization of the soil had only a slight effect on the intensity of processes related to the mineralization of nitrogen - proteolysis and ammonification. The nitrification power of the soil was considerably increased by the application of large doses of manure, sewage sludge and defecation lime. Nitrification was limited in the soil with a large dose of keratin-bark-urea granulate