Accurately Predicting a Herbicide's Potential

Abstract

Field screening methods were developed which proved very reliable in accurately assessing the potential of herbicides during the first year of testing. Under conditions imposed by these methods, the herbicides usually exhibited maximum toxicity, thereby indicating which ones might be potentially hazardous in growers' fields when crop tolerance is lowered by adverse growing conditions. Of the 29 crop uses suggested by the data, 16 are registered by the USDA and are now in current use. Of these 29, 26 were indicated during the first year of testing and substantiated by data from an additional 1 to 4 years of testing.

Supersonic cloud collision – II

“…This is a time sequence of column density plots of the gas slab, as seen face-on. The nature of fragmentation observed here is in consonance with the predictions of Whitworth et al (1994) for an off-centre cloud collision, with a small impact parameter.…”

“…Expressions for the length of the fastest growing mode, the timescale of growth of this mode and the minimum mass of the fragment condensing out of the slab have been derived by (Whitworth et al 1994) and Boyd & Whitworth (2005). Below we discuss the models tested in this work and compare the results of models 3 and 4 with the analytic findings of the latter authors.…”

“…The gas slab in this case is not sufficiently massive, or in other words, it is not sufficiently cold (for the mass that it has) so as to support the Jeans instability. According to Whitworth et al (1994), the length of the fastest growing unstable mode is…”

“…See for e.g. Elmegreen & Elmegreen (1978), Whitworth et al (1994), Clarke (1999), and Boyd & Whitworth (2005). Such slabs result from clouds colliding with relatively small precollision Mach numbers (e.g.…”