A survey of the problem and research needs in the coastal zone

Coastal zone oceanography emphasizing pollution and geological processes - bibliograph

Impact-induced acceleration by obstacles

We explore a surprising phenomenon in which an obstruction accelerates, rather than decelerates, a moving flexible object. It has been claimed that the right kind of discrete chain falling onto a table falls \emph{faster} than a free-falling body. We confirm and quantify this effect, reveal its complicated dependence on angle of incidence, and identify multiple operative mechanisms. Prior theories for direct impact onto flat surfaces, which involve a single constitutive parameter, match our data well if we account for a characteristic delay length that must impinge before the onset of excess acceleration. Our measurements provide a robust determination of this parameter. This supports the possibility of modeling such discrete structures as continuous bodies with a complicated constitutive law of impact that includes angle of incidence as an input.Comment: small changes and corrections, added reference

Debate on the Tithe

https://digitalcommons.acu.edu/crs_books/1603/thumbnail.jp

Conservation Tillage: Adjustment and operation of planters in systems with high levels of surface residue

This publication suggests tillage operation adjustments that may leave an additional 10 to 15 percent surface residue beyond what current practices leave with a chisel plow or disk system.https://lib.dr.iastate.edu/extension_ag_pubs/1098/thumbnail.jp

Spin Susceptibility and Gap Structure of the Fractional-Statistics Gas

This paper establishes and tests procedures which can determine the electron energy gap of the high-temperature superconductors using the $t\!-\!J$ model with spinon and holon quasiparticles obeying fractional statistics. A simpler problem with similar physics, the spin susceptibility spectrum of the spin 1/2 fractional-statistics gas, is studied. Interactions with the density oscillations of the system substantially decrease the spin gap to a value of $(0.2 \pm 0.2)$ $\hbar \omega_c$, much less than the mean-field value of $\hbar\omega_c$. The lower few Landau levels remain visible, though broadened and shifted, in the spin susceptibility. As a check of the methods, the single-particle Green's function of the non-interacting Bose gas viewed in the fermionic representation, as computed by the same approximation scheme, agrees well with the exact results. The same mechanism would reduce the gap of the $t\!-\!J$ model without eliminating it.Comment: 35 pages, written in REVTeX, 16 figures available upon request from [email protected]

Foliar fungicide application techniques on soybeans

Soybeans (Glycine max L.) are a major commodity crop grown on over 29 million hectare (72 million acres) in the United States. A large part of the cropland base in Iowa, 5 million hectare (11 to 13 million acres) annually, is devoted to soybean production. Although long term crop yield trends are upward, soybean yield increases have been more stagnant than corn, the common companion rotational crop, causing growers to question factors such as disease that might be slowing yield growth. In late 2004 Asian Soybean Rust (Phahopsora pachyrhizi) was detected in the United States. Because of the potential for yield loss as observed in other countries, grower concern has resulted in increased interest in this and other foliar leaf spot diseases that may be affecting yield. Midwestern U.S. agronomic row-crop growers are generally familiar and experienced with herbicide and insecticide application, but have very limited experiences in field application of fungicides. Growers customarily have existing sprayer equipment set up to apply systemic herbicides with relatively large droplets to reduce drift and carrier application rates of 94 to 14 3L/ha (10 to 15 gal/acre) to minimize water transported and maximize the range of application area covered by an individual tank

Effects of Nozzle Type and Carrier Application on the Control of Leaf Spot Diseases of Soybean

Midwestern soybean growers seek information on effective application of foliar fungicides that do not translocate throughout the plant. Field application treatments included using a two-orifice nozzle tip producing fine droplets at 187 l/ha (20 gal/ac) and 112 l/ha (12 gal/ac) and a single-orifice nozzle tip producing a coarse droplet size more typical of herbicide applications at 168 l/ha (18 gal/ac). In addition an air-assisted sprayer was used at one of the two sites of the trials. Measurements included droplet size, droplet coverage, and foliar disease severity in the top, middle, and lower parts of the plant canopy, and soybean yield. Droplet size for application treatments generally followed expected manufacturer specifications. Percentage area covered and drops/cm 2 were not statistically different among application treatments except at top of the plant canopy at one site. Percentage area covered and drops/cm 2 were statistically greater at the top of the canopy (17 - 18% coverage) than at the middle or bottom (1 – 8% coverage) at both sites. Foliar disease pressure was light so that yield or disease severity was unaffected by application method or as compared to a check area without application