Measurement of electron density and temperature in plasmas

Application of two laser wavelengths passing through plasma measures electron density and temperature. Function depends on determining absorption of light at two wavelengths. Nature of reaction is explained and schematic diagram of equipment is included

On the calculation of supersonic, separating, and reattaching flows

A method is developed for solving the laminar and turbulent compressible boundary-layer equations for separating and reattaching flows. Results of this method are compared with experimental data for two laminar and three turbulent boundary-layer, shock-wave interactions. Several Navier-Stokes solutions were obtained for each of the laminar boundary-layer, shock-wave interactions considered. Comparison of these solutions indicates a first-order sensitivity in C sub f to the computational mesh selected in both the viscous and inviscid portions of the flow

Application of shock tubes to transonic airfoil testing at high Reynolds numbers

Performance analysis of a gas-driven shock tube shows that transonic airfoil flows with chord Reynolds numbers of the order of 100 million can be produced, with limitations being imposed by the structural integrity of the facility or the model. A study of flow development over a simple circular arc airfoil at zero angle of attack was carried out in a shock tube at low and intermediate Reynolds numbers to assess the testing technique. Results obtained from schlieren photography and airfoil pressure measurements show that steady transonic flows similar to those produced for the same airfoil in a wind tunnel can be generated within the available testing time in a shock tube with properly contoured test section walls

Relative importance of host environment, transmission potential and host phylogeny to the structure of parasite metacommunities

Identification of mechanisms that shape parasite community and metacommunity structures have important implications to host health, disease transmission, and the understanding of community assembly in general. Using a long-term dataset on parasites from desert rodents, we examined the relative contributions of host traits that represent important aspects of parasite environment, transmission probability between host species, and host phylogeny to the structure of a parasite metacommunity as well as for taxonomically restricted parasite metacommunities (coccidians, ectoparasites and helminths). This was done using a combination of metacommunity analysis and variance partitioning based on canonical correspondence analysis. Coccidian and ectoparasite metacommunities did not exhibit coherent structure. In contrast, helminths and the full parasite metacommunity had Clementsian and quasi-Clementsian structure, respectively, indicating that parasite species distributions for these metacommunities were compartmentalized along a dominant gradient. Variance decomposition indicated that characteristics associated with the host environment consistently explained more variation than did host traits associated with transmission opportunities or host phylogeny, indicating that the host environment is primary in shaping parasite species distributions among host species. Moreover, the importance of different types of host traits in structuring parasite metacommunities was consistent among taxonomic groups (i.e. full metacommunity, coccidians, and helminths) despite manifest differences in emergent structures (i.e. Clementsian, quasi-Clementsian, and random) that arose in response to variation in host environment. © 2014 The Authors

A simple squeezer for removal of interstitial water from ocean sediments

A simple and inexpensive squeezer employed in the removal of interstitial water from ocean sediments has been designed. Squeezing is carried out with nitrogen at pressures of 500 to 1000 lb/in2 (35 to 70 kg/cm2). The apparatus is lined with teflon, thus insuring complete freedom from metallic contamination

Evaluating Multi-Species Cover Crops for Forage Production

Cover crops offer potential benefits for improving soil health, but establishment and management costs can be expensive. One way for farmers to recover these costs is to graze the forage, which benefits producers by integrating crop and animal production. More information is needed on the potential forage quantity and quality for grazing livestock of cover crops and mixed species of cover crops. Researchers have suggested that different plant species complement each other, but additional work is needed to determine how best to balance forage production and how competitive the various species are when added to a mix. Sixteen treatments were drill-seeded at the Southeast Research and Extension Center near Columbus, Kansas, in August 2014 and 2015. Each treatment consisted of a three-way mix representing popular cover crops from the plant families Brassicaceae (brassicas), Poaceae (grasses), and Fabaceae (legumes). Eight species were planted, including forage radish (Raphanus sativus), purple-top turnip (Brassica rapa), oat (Avena sativa), rye (Secale cereale), barley (Hordeum vulgare), wheat (Triticum aestivum), Austrian winter pea (Pisum sativum subsp. arvense), and berseem clover (Trifolium alexandrinum). Small areas of each plot were clipped at 45-, 74-, and 91-day intervals each year. The clipped biomass was then weighed, sorted, and dried to determine biomass as well as species composition. In 2014 the average biomass produced at 45, 74, and 91 days was 1,250, 3,290, and 3,050 lb/ac, respectively. These range from 470–1,940 lb/ac 45 days after planting to 1,790–4,440 lb/ac at 91 days after planting, depending on the cover crop mix. In 2015, the average biomass at 45, 74, and 91 days was 1,120, 1,604, and 2,273 lb/ac, respectively. These range from 557-1,876 lb/ ac 45 days after planting to 1,100–4,127 lb/ac at 91 days after planting, depending on the cover crop mix

Improving Yield Stability and Resiliency of Agronomic Production Systems in Southeast Kansas

Soil health is a critical determinant of crop performance. Soil physical, chemical, and biological properties can be modified through production practices such as tillage. Use of cover crops has been shown to benefit soil health and may improve productive capacity of soils. High rainfall and intense crop production practices limit the ability to implement cover crops in current production systems in southeast Kansas. This study explores potential management of cover crops and their contribution to soil health, crop productivity, and animal grazing