Phase resolved PLIF and chemiluminescence for measuring combustion dynamics

Transient behavior of combustion systems has long been a subject of both fundamental and practical concerns. Extreme cases of very rapid changes include the ignition of reacting mixtures and detonation. At the other extreme is a wide range of quasi-steady changes of behavior, for example adjustments of the operating point of a combustion chamber. Between the limiting cases of 'infinitely fast' and 'infinitesimally slow' lie important fundamental problems of time-dependent behavior and a wide array of practical applications. Among the latter are combustion instabilities and their active control, a primary motivation for the work reported in this paper. Owing to the complicated chemistry, chemical kinetics and flow dynamics of actual combustion systems, numerical simulations of their behavior remains in a relatively primitive state. Even as that situation continually improves, it is an essential part of the field that methods of measuring true dynamical behavior be developed to provide results having both fine spatial resolution and accuracy in time. This paper is a progress report of recent research carried out in the Jet Propulsion Center of the California Institute of Technology

Cotton seed and seedling diseases and their control

"Seedling diseases cause serious losses to Missouri cotton each year. Failure to get a uniform stand of cotton is due largely to seedling diseases. Cold, wet soils are conducive to most seedling diseases. These conditions occur frequently in Missouri. Injuries caused by these diseases can result in stand losses that necessitate replanting. The U.S. Cotton Disease Council reports that seedling diseases cause average losses of 3 percent nationally. Farmers in southeast Missouri lose 5 percent annually to seedling disease."--First page.James A. Wrather and Einar W. Palm (Department of Plant Pathology College of Agriculture)Revised 2/88/4

Sorghum aphid pest management (1985)

Revised 4/85/10M, New 4/92/5M

The soybean cyst nematode

"The soybean cyst nematode, Heterodera glycines Ichinohe, attacks soybean roots and is a serious threat to the crop in many soybean growing areas. This tiny, parasitic roundworm is so named because the female body, when filled with eggs, is known as a cyst. Cysts may remain in and infest soil for several years. The nematodes' persistence and rapid production, along with the severe injuries they cause to host-plant roots, make the nematodes a serious agricultural threat."--First page.Einar W. Palm, J. A Wrather (Department of Plant Pathology), and Sam Anand (Department of Agronomy, College of Agriculture)Revised 11/86/8

Methanogenic \u3cem\u3eArchaea\u3c/em\u3e and human periodontal disease

Archaea have been isolated from the human colon, vagina, and oral cavity, but have not been established as causes of human disease. In this study, we reveal a relationship between the severity of periodontal disease and the relative abundance of archaeal small subunit ribosomal RNA genes (SSU rDNA) in the subgingival crevice by using quantitative PCR. Furthermore, the relative abundance of archaeal small subunit rDNA decreased at treated sites in association with clinical improvement. Archaea were harbored by 36% of periodontitis patients and were restricted to subgingival sites with periodontal disease. The presence of archaeal cells at these sites was confirmed by fluorescent in situ hybridization. The archaeal community at diseased sites was dominated by a Methanobrevibacter oralis-like phylotype and a distinct Methanobrevibacter subpopulation related to archaea that inhabit the gut of numerous animals. We hypothesize that methanogens participate in syntrophic relationships in the subgingival crevice that promote colonization by secondary fermenters during periodontitis. Because they are potential alternative syntrophic partners, our finding of larger Treponema populations sites without archaea provides further support for this hypothesis

Turfgrass disease control -- cultural

"These three factors are like the sides of a triangle, as long as each is present the triangle is complete and there is potential for a disease to occur. If one of the three factors is missing then the triangle is broken and disease will not occur."--First page.D.D. Minner, P.A. Donald and E.W. Palm (University of Missouri, College of Agriculture)New 5/90/7