1,053 research outputs found

    Recommendations for chemical weed control in grain sorghum

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    12/77/15MHarold Kerr, Joseph H. Scott, O. Hale Fletchall and L. E. Anderson (Department of Agronomy, College of Agriculture

    Agroforestry interactions and soil water use in watersheds under corn-soybean management

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    Paper presented at the 11th North American Agroforesty Conference, which was held May 31-June 3, 2009 in Columbia, Missouri.In Gold, M.A. and M.M. Hall, eds. Agroforestry Comes of Age: Putting Science into Practice. Proceedings, 11th North American Agroforestry Conference, Columbia, Mo., May 31-June 3, 2009.Agroforestry and grass buffer practices reduce non point source pollution from corn-soybean watersheds, yet little is known about the processes and mechanisms involved. The objective of this study was to compare the soil water dynamics in crop, grass, and agroforestry areas throughout the growing season to understand soil water use and recharge differences among the treatments. The study was conducted on two corn (Zea mays L.)-soybean (Glycine max (L.) Merr.) rotational watersheds with grass and agroforestry buffers at the Greenley Research Center, Knox County, MO. Campbell soil moisture sensors were installed in crop, grass, and agroforestry areas with six replications at 5, 10, 20, and 40 cm depths to record volumetric soil water content at 10 minute intervals for 2004 through 2007. Initial soil moisture was lower in tree and grass buffer areas than crop areas probably due to water use by the permanent vegetation before crops were established. The differences were larger for shallower depths as compared to the 40 cm depth. The trend continued throughout the growing season. Weekly soil moisture content was significantly higher in the crop treatment as compared to the buffer treatments. During rain events water content increased in all depths and treatments and the differences in water content among treatments diminished. At the end of the growing season, soil water content increased when water use was low and as the profile recharged by rain events. The results of the study suggest that establishment of grass and agroforestry buffers help reduce non point source pollution from row crop agriculture by using additional water that would have otherwise have been lost in runoff carrying sediments, nutrients, and pesticides.Ranjith P. Udawatta (1,2), Stephen H. Anderson (1), Peter P. Motavalli (1), and Harold E. Garrett (2) ; 1. Department of Soil, Environmental and Atmospheric Sciences. 2. Center for Agroforestry, and University of Missouri, Columbia, MO 65211.Includes bibliographical references

    Highly Efficient Design-of-Experiments Methods for Combining CFD Analysis and Experimental Data

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    It is the purpose of this study to examine the impact of "highly efficient" Design-of-Experiments (DOE) methods for combining sets of CFD generated analysis data with smaller sets of Experimental test data in order to accurately predict performance results where experimental test data were not obtained. The study examines the impact of micro-ramp flow control on the shock wave boundary layer (SWBL) interaction where a complete paired set of data exist from both CFD analysis and Experimental measurements By combining the complete set of CFD analysis data composed of fifteen (15) cases with a smaller subset of experimental test data containing four/five (4/5) cases, compound data sets (CFD/EXP) were generated which allows the prediction of the complete set of Experimental results No statistical difference were found to exist between the combined (CFD/EXP) generated data sets and the complete Experimental data set composed of fifteen (15) cases. The same optimal micro-ramp configuration was obtained using the (CFD/EXP) generated data as obtained with the complete set of Experimental data, and the DOE response surfaces generated by the two data sets were also not statistically different

    On the Sign Problem in the Hirsch-Fye Algorithm for Impurity Problems

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    We show that there is no fermion sign problem in the Hirsch and Fye algorithm for the single-impurity Anderson model. Beyond the particle-hole symmetric case for which a simple proof exists, this has been known only empirically. Here we prove the nonexistence of a sign problem for the general case by showing that each spin trace for a given Ising configuration is separately positive. We further use this insight to analyze under what conditions orbitally degenerate Anderson models or the two-impurity Anderson model develop a sign.Comment: 2 pages, no figure; published versio

    Chemical weed control in field corn for 1982 -- part 1 : preplanting incorporated treatments

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    Harold D. Kerr, Joseph H. Scott, E. J. Peters, L. E. Anderson, O. Hale Fletchall, David Guethle, Zane R. Helsel and Howard Guscar (Department of Agronomy, College of Agriculture)New 1/82/15

    Chemical weed control in field corn for 1982, Part 2. Pre-emergence and postemergence

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    Harold D. Kerr, Joseph H. Scott, E. J. Peters, L. E. Anderson, O. Hale Fletchall, David Guethle, Zane R. Helsel and Howard Guscar (Department of Agronomy, College of Agriculture)Revised 1/82/15

    Brain Networks Associated with Cognitive Reserve in Healthy Young and Old Adults

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    In order to understand the brain networks that mediate cognitive reserve, we explored the relationship between subjects' network expression during the performance of a memory test and an index of cognitive reserve. Using H215O positron emission tomography, we imaged 17 healthy older subjects and 20 young adults while they performed a serial recognition memory task for nonsense shapes under two conditions: low demand, with a unique shape presented in each study trial; and titrated demand, with a study list size adjusted so that each subject recognized shapes at 75% accuracy. A factor score that summarized years of education, and scores on the NART and the WAIS-R Vocabulary subtest was used as an index of cognitive reserve. The scaled subprofile model was used to identify a set of functionally connected regions (or topography) that changed in expression across the two task conditions and was differentially expressed by the young and elderly subjects. The regions most active in this topography consisted of right hippocampus, posterior insula, thalamus, and right and left operculum; we found concomitant deactivation in right lingual gyrus, inferior parietal lobe and association cortex, left posterior cingulate, and right and left calcarine cortex. Young subjects with higher cognitive reserve showed increased expression of the topography across the two task conditions. Because this topography, which is responsive to increased task demands, was differentially expressed as a function of reserve level, it may represent a neural manifestation of innate or acquired reserve. In contrast, older subjects with higher cognitive reserve showed decreased expression of the topography across tasks. This suggests some functional reorganization of the network used by the young subjects. Thus, for the old subjects this topography may represent an altered, compensatory network that is used to maintain function in the face of age-related physiological changes
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