Determination of Thermal and Blue Light Photochemical Hazard Protection needed by Automatic Welding filters

Recent developments in biological research, has shown that the initial maximum permissible exposure (MPE) limits for protection of workers from risks associated with artificial optical radiations were more stringent than needed. Using the most recent MPE limits for artificial optical radiation this piece of work was focused on the investigation of the level of visible light attenuation needed by automatic welding filters in case of switching failure. Results from the comparison of different exposure standards were employed in investigating the need of Vis/IR and blue light transmittance requirement for automatic welding filters. Real and arbitrary spectra were taken into consideration for the worst and best case scenarios of artificial optical radiations. An excel worksheet developed during the execution of this project took into consideration the exposure from different light sources and the precision of the spectrometer used in measuring the transmittances of a welding filter. The worksheet was developed and tested with known product properties to investigate the validity of its formulation. The conclusion drawn from this project was that attenuation in the light state will be needed for products with the darkest state shade 11 or higher. Also shown is that current welding filter protects the eye well enough even in the case of switching failure.

The influence of sex, age, and race experience on pacing profiles during the 90 km Vasaloppet ski race

The purpose of this study was to investigate pacing-profile differences during the 90 km Vasaloppet ski race related to the categories of sex, age, and race experience. Skiing times from eight sections (S1 to S8) were analyzed. For each of the three categories, 400 pairs of skiers were matched to have a finish time within 60 seconds, the same start group, and an assignment to the same group for the other two categories. Paired-samples Student’s t-tests were used to investigate sectional pacing-profile differences between the subgroups. Results showed that males skied faster in S2 (P=0.0042), S3 (P=0.0049), S4 (P=0.010), and S1–S4 (P<0.001), whereas females skied faster in S6 (P<0.001), S7 (P<0.001), S8 (P=0.0088), and S5–S8 (P<0.001). For the age category, old subjects (40 to 59 years) skied faster than young subjects (19 to 39 years) in S3 (P=0.0029), and for the other sections, there were no differences. Experienced subjects (≥4 Vasaloppet ski race completions) skied faster in S1 (P<0.001) and S1–S4 (P=0.0054); inexperienced skiers (<4 Vasaloppet ski race completions) had a shorter mean skiing time in S5–S8 (P=0.0063). In conclusion, females had a more even pacing profile than that of males with the same finish time, start group, age, and race experience. No clear age-related pacing-profile difference was identified for the matched subgroups. Moreover, experienced skiers skied faster in the first half whereas inexperienced skiers had higher skiing speeds during the second half of the race.