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Mechanical weeders were tested on both mineral and organic soils in 1995 and in 1996, to measure their impact on soil physical properties. The weeders were tested in three crops, carrots in mineral and organic soil, beans in mineral soil, and lettuce in organic soil. Soil bulk density and water content were measured at regular intervals during the weeder trial period, and samples for soil structural analysis were collected in the mineral soil at the beginning and at the end of each season. / No significant results were found in differences in mean weight diameters of dry and water-stable aggregates. Soil moisture did not vary significantly due to treatment. There was significant compaction caused by the first pass in the field (i.e., seeder) in all the crops at both sites in the 0--10 cm layer, and in some cases, to a depth of 25 cm. Additional field passes with the weeders caused some compaction in the tractor wheel at the 0--10 cm depth, and sometimes in the 10--25 cm layer, in all trials in mineral soil, yet no significant effects of treatments were detected in the trials at the organic soil site. No conclusions could be drawn as to the benefits and/or negative impacts of mechanical versus chemical weeding in mineral soil, with respect to the relative compaction caused by the mechanical weeders. This is because in this experiment spraying of herbicides did not involve tractor traffic in the field.

Shell geometry is one of the many variables that can influence the way energy is absorbed by the helmet during impact. The purpose of this study was to gain knowledge in how shell geometry affects the performance of the shell relative to liner structural characteristics and impact conditions. Samples, representing a section of a hockey helmet, consisted of a shell with one of nine geometric formations (width and angle), and a liner (Dertex or EPP). Each sample was impacted three times at three different levels of energy using a monorail drop test. Significant differences were observed for all main effects and two-way interactions for both liner types. Overall the 90 degree angle and 16mm width performed the best. It was found that geometry influences the elastic properties of the shell in a very specific way. It was also found that geometry can improve energy absorption by 4-35% depending on the combination of other variables involved.

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This creative project presents a comprehensive and detailed guide to the building of inexpensive studio lighting equipment. The projects include simple equipment such as backgrounds, snoots and scrims to more specialized equipment like the glassware table and softlight box.Each project includes figures and instructions for building the equipment. At the end of each project are examples of the effects of each piece of equipment in a photographic situation.Also included is a list of photographic data on how each of the photographs was taken.