Helicopter sling load accident/incident survey: 1968 - 1974

During the period considered a mean of eleven accidents per year occurred and a mean of eleven persons were killed or seriously injured per year. Forty-one percent of the accidents occurred during hover, and 63 percent of the accidents had pilot error listed as a cause/factor. Many accidents involved pilots losing control of the helicopter or allowing a collision with obstructions to occur. There was a mean of 58 incidents each year and 51 percent of these occurred during cruise

Three flavors of extremal Betti tables

We discuss extremal Betti tables of resolutions in three different contexts. We begin over the graded polynomial ring, where extremal Betti tables correspond to pure resolutions. We then contrast this behavior with that of extremal Betti tables over regular local rings and over a bigraded ring.Comment: 20 page

Multiple inducers of the Drosophila heat shock locus 93D (hsr omega): inducer-specific patterns of the three transcripts

The Drosophila hsr omega locus produces one of the largest and most active heat shock puffs, yet it does not encode a heat shock protein. Instead, this locus produces a distinctive set of three transcripts, all from the same start site. The largest transcript, omega 1, is limited to the nucleus and appears to have a role there. A second nuclear transcript, omega 2, is produced by alternative termination and contains the sequence found in the 5' 20-25% of omega 1 (depending on the Drosophila species). The cytoplasmic transcript, omega 3, is produced by removal of a 700-bp intron from omega 2. All three hsr omega RNAs are produced constitutively and production is enhanced by heat shock. In addition to being a member of the set of heat shock puffs, the hsr omega puff is induced by agents that do not affect other heat shock loci, suggesting that hsr omega is more sensitive to environmental changes than other loci. We report here that agents that induce puffing of hsr omega loci in polytene nuclei also lead to an increase in hsr omega transcripts in diploid cells. We also show that the relative levels of omega 1 and omega 3 can be modulated independently by several agents. All drugs that inhibit translation, either initiation or elongation, stabilize the omega 3 transcript, which normally turns over within minutes in control cells. Drugs (such as benzamide and colchicine) that induce puffing of hsr omega, but not other heat shock loci, lead to large increases in omega 1. Although the constitutive level of omega 1 is relatively stable, the drug-induced excess is lost rapidly when the drug is withdrawn. The relative levels of hsr omega transcripts may reflect different states in cellular metabolism

Estimation of Chemical Incompatibility (Other-Chemical Reactivity) By Computer

Author Institution: 2626 Chartwell Road, Columbus, OH 43220 ; Columbus LaboratoriesTwo simple parameters—the National Academy of Science-National Research Council Other Chemical rating and a Lewis acid-base rating were combined in a linear discriminate model to predict the degree of hazard from binary mixtures as measured by Dow Chemical experimental tests. The observed error of 10% compares favorably with 40% error obtained using the NAS-NRC rating system. These results will be incorporated in the American Society for Testing and Materials computer program CHETAH (Chemical Thermodynamics and Energy Hazard Potential)