1,053 research outputs found
Recommendations for chemical weed control in grain sorghum
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
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
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
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
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Cognitive Reserve Modulates Functional Brain Responses During Memory Tasks: A Pet Study in Healthy Young and Elderly Subjects
Cognitive reserve (CR) is the ability of an individual to cope with advancing brain pathology so that he remains free of symptomatology. Epidemiological evidence and in vivo neurometabolic data suggest that CR may be mediated through education or IQ. The goal of this study was to investigate CR-mediated differential brain activation in 17 healthy young adults and 19 healthy elders. Using nonquantitative H(2)(15)O PET scanning, we assessed relative regional cerebral blood flow while subjects performed a serial recognition memory task under two conditions: nonmemory control (NMC), in which one shape was presented in each study trial; and titrated demand (TD), in which study list length was adjusted so that each subject recognized shapes at approximately 75% accuracy. A factor score that summarized years of education and scores on two IQ indices was used as an index of CR. Voxel-wise, multiple regression analyses were performed with TD minus NMC difference PET counts as the dependent variable and the CR variable as the independent variable of interest. We identified brain regions where regression slopes were different from zero in each separate group, and also those where regression slopes differed between the two age groups. The slopes were significantly more positive in the young in the right inferior temporal gyrus, right postcentral gyrus, and cingulate, while the elderly had a significantly more positive slope in left cuneus. Brain regions where systematic relationships between CR and brain activation differ as a function of aging are loci where compensation for aging has occurred. They may mediate differential ability to cope with brain changes in aging
Chemical weed control in field corn for 1982 -- part 1 : preplanting incorporated treatments
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
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
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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Cardiac Biomarkers and Risk of Atrial Fibrillation in Chronic Kidney Disease: The CRIC Study.
Background We tested associations of cardiac biomarkers of myocardial stretch, injury, inflammation, and fibrosis with the risk of incident atrial fibrillation (AF) in a prospective study of chronic kidney disease patients. Methods and Results The study sample was 3053 participants with chronic kidney disease in the multicenter CRIC (Chronic Renal Insufficiency Cohort) study who were not identified as having AF at baseline. Cardiac biomarkers, measured at baseline, were NT-proBNP (N-terminal pro-B-type natriuretic peptide), high-sensitivity troponin T, galectin-3, growth differentiation factor-15, and soluble ST-2. Incident AF ("AF event") was defined as a hospitalization for AF. During a median follow-up of 8 years, 279 (9%) participants developed a new AF event. In adjusted models, higher baseline log-transformed NT-proBNP (N-terminal pro-B-type natriuretic peptide) was associated with incident AF (adjusted hazard ratio [HR] per SD higher concentration: 2.11; 95% CI, 1.75, 2.55), as was log-high-sensitivity troponin T (HR 1.42; 95% CI, 1.20, 1.68). These associations showed a dose-response relationship in categorical analyses. Although log-soluble ST-2 was associated with AF risk in continuous models (HR per SD higher concentration 1.35; 95% CI, 1.16, 1.58), this association was not consistent in categorical analyses. Log-galectin-3 (HR 1.05; 95% CI, 0.91, 1.22) and log-growth differentiation factor-15 (HR 1.16; 95% CI, 0.96, 1.40) were not significantly associated with incident AF. Conclusions We found strong associations between higher NT-proBNP (N-terminal pro-B-type natriuretic peptide) and high-sensitivity troponin T concentrations, and the risk of incident AF in a large cohort of participants with chronic kidney disease. Increased atrial myocardial stretch and myocardial cell injury may be implicated in the high burden of AF in patients with chronic kidney disease
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Research-based versus clinical serum creatinine measurements and the association of acute kidney injury with subsequent kidney function: findings from the Chronic Renal Insufficiency Cohort study.
Background:Observational studies relying on clinically obtained data have shown that acute kidney injury (AKI) is linked to accelerated chronic kidney disease (CKD) progression. However, prior reports lacked uniform collection of important confounders such as proteinuria and pre-AKI kidney function trajectory, and may be susceptible to ascertainment bias, as patients may be more likely to undergo kidney function testing after AKI. Methods:We studied 444 adults with CKD who participated in the prospective Chronic Renal Insufficiency Cohort (CRIC) Study and were concurrent members of a large integrated healthcare delivery system. We estimated glomerular filtration rate (eGFR) trajectories using serum creatinine measurements from (i) the CRIC research protocol (yearly) and (ii) routine clinical care. We used linear mixed effects models to evaluate the associations of AKI with acute absolute change in eGFR and post-AKI eGFR slope, and explored whether these varied by source of creatinine results. Models were adjusted for demographic characteristics, diabetes status and albuminuria. Results:During median follow-up of 8.5 years, mean rate of eGFR loss was -0.31 mL/min/1.73 m2/year overall, and 73 individuals experienced AKI (55% Stage 1). A significant interaction existed between AKI and source of serum creatinine for acute absolute change in eGFR level after discharge; in contrast, AKI was independently associated with a faster rate of eGFR decline (mean additional loss of -0.67 mL/min/1.73 m2/year), which was not impacted by source of serum creatinine. Conclusions:AKI is independently associated with subsequent steeper eGFR decline regardless of the serum creatinine source used, but the strength of association is smaller than observed in prior studies after taking into account key confounders such as pre-AKI eGFR slope and albuminuria
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