An experimental study of the control of condensate subcooling in a vertical condenser

Temperature control of subcooled reflux in a distillation column was studied experimentally using coolant flow rate as the manipulative variable. Methanol vapor was condensed and subcooled at one atmosphere in a vertical heat exchanger with 210 copper tubes (0.77 cm I.D., 91.5 cm long). Cooling water flowed countercurrently through the shell side (20.6 cm I.D.). A proportional-integral feedback controller provided good temperature control at normal design throughputs. But dynamic control performance deteriorated at low throughputs (or large areas). Thus the normal conservative design practice of providing excess area in this type of condenser leads to poorer temperature control.     

Gender and neurogenic variables in tendon biology and repetitive motion disorders

The incidence of repetitive motion disorders is increasing. Numerous studies have indicated that the incidence in females exceeds that in males. Some of the evidence regarding gender related factors in tendon biology is discussed and new data related to the regulation of gene expression in an animal model of tendon overuse, the determination of sex hormone receptors in tendons, and the influence of pregnancy associated factors on gene expression in four different tendons is provided. Furthermore, because neurogenic mechanisms may contribute to inflammatory conditions, new evidence is provided that supports the concept that neurotransmitters can influence expression of genes that could participate in such inflammation. By increasing our understanding of the regulation of tendon cellular and molecular biology, new approaches to preventing disease development and treatment of existing disease may evolve.     

Créativité et composition fran?aise chez des enfants de cinquième année scolaire.

Assessed and modified creativity in composition among 48 French-Canadian 5th graders by reinforcing certain objective components of the French language. The specific influence of the reinforcing agent (free activities) was isolated using a control group submitted to instructions only. Results show that (1) a period of free activities improved the use of the different components and was significantly better than instructions only, (2) the creativity in compositions was higher when Ss used a greater number of different nouns and verbs, and (3) the self-correction technique was time-saving and easy to apply. (English abstract) (13 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)