Power output of field-based downhill mountain biking

The purpose of this study was to assess the power output of field-based downhill mountain biking. Seventeen trained male downhill cyclists (age 27.1 +/- 5.1 years) competing nationally performed two timed runs of a measured downhill course. An SRM powermeter was used to simultaneously record power, cadence, and speed. Values were sampled at 1-s intervals. Heart rates were recorded at 5-s intervals using a Polar S710 heart rate monitor. Peak and mean power output were 834 +/- 129 W and 75 +/- 26 W respectively. Mean power accounted for only 9% of peak values. Paradoxically, mean heart rate was 168 +/- 9 beats x min(-1) (89% of age-predicted maximum heart rate). Mean cadence (27 +/- 5 rev x min(-1)) was significantly related to speed (r = 0.51; P < 0.01). Analysis revealed an average of 38 pedal actions per run, with average pedalling periods of 5 s. Power and cadence were not significantly related to run time or any other variable. Our results support the intermittent nature of downhill mountain biking. The poor relationships between power and run time and between cadence and run time suggest they are not essential pre-requisites to downhill mountain biking performance and indicate the importance of riding dynamics to overall performance.     

Climate control through ionization

This paper summarizes some of the experimental evidence of the apparent biological effects produced by atmospheric ionization. Thermionic ion sources are discussed and the results of experimental determinations of their characteristics are presented.     

Linguistic influences on professional communication and recognition: A study of chemists and engineers in two Quebec universities

Linguistic influences on networks of professional communication and recognition among engineers at two Quebec universities were examined. It was hypothesized that chemists and engineers affiliated with the French medium University of Montreal and the Ecole Polytechnique would be less active in research and more likely to obtain scientific recognition locally and to feel professionally unrecognized outside Quebec compared to their colleagues at McGill University. The findings suggest that the localizing effects of using a medium of scientific training which is not the predominant language of international scientific communication and recognition (French) are ambiguous. Although chemists and engineers at the French medium institutions were less active researchers, their language of professional communication with other scientific communities was English and there was little sense of isolation.This research has been supported by grants from the Canadian Council and the Ecole Polytechnique of Montreal. The authors also wish to thank Miss Madeleine Palmer, Miss Daniella Quiniou and Miss Rosalba Casas for their help in data collection for this paper.