University of Arkansas

About: University of Arkansas is a education organization based out in Fayetteville, Arkansas, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 17225 authors who have published 33329 publications receiving 941102 citations. The organization is also known as: Arkansas & UA.

Does function follow form? Principal QTLs for Fusarium head blight (FHB) resistance are coincident with QTLs for inflorescence traits and plant height in a doubled-haploid population of barley

Abstract: Fusarium head blight (FHB), an important disease of barley in many areas of the world, causes losses in grain yield and quality. Deoxynivalenol (DON) mycotoxin residues, produced by the primary pathogen Fusarium graminearum, pose potential health risks. Barley producers may not be able to profitably market FHB-infected barley, even though it has a low DON level. Three types of FHB resistance have been described in wheat: Type I (penetration), Type II (spread), and Type III (mycotoxin degradation). We describe putative measures of these three types of resistance in barley. In wheat, the three resistance mechanisms show quantitative inheritance. Accordingly, to study FHB resistance in barley, we used quantitative trait locus (QTL) mapping to determine the number, genome location, and effects of QTLs associated with Type-I and -II resistance and the concentration of DON in the grain. We also mapped QTLs for plant height, heading date, and morphological attributes of the inflorescence (seeds per inflorescence, inflorescence density, and lateral floret size). QTL analyses were based on a mapping population of F1-derived doubled-haploid (DH) lines from the cross of the two-rowed genotypes Gobernadora and CMB643, a linkage map constructed with RFLP marker loci, and field evaluations of the three types of FHB resistance performed in China, Mexico, and two environments in North Dakota, USA. Resistance QTLs were detected in six of the seven linkage groups. Alternate favorable alleles were found at the same loci when different inoculation techniques were used to measure Type-I resistance. The largest-effect resistance QTL (for Type-II resistance) was mapped in the centromeric region of chromosome 2. All but two of the resistance QTLs coincided with QTLs determining morphological attributes of the inflorescence and/or plant height. Additional experiments are needed to determine if these coincident QTLs are due to linkage or pleiotropy and to more clearly define the biological basis of the FHB resistance QTLs. Plant architecture should be considered in FHB resistance breeding efforts, particularly those directed at resistance QTL introgression and/or pyramiding.

A solution to the worn tooth conundrum in primate functional anatomy

Abstract: Worn teeth are a bane to paleobiologists interested in the diets of human ancestors and other fossil primates. Although worn teeth dominate fossil assemblages, their shapes are usually not used to reconstruct the diets of extinct species. The problem is that traditional studies of primate dental functional anatomy have focused on unworn morphology. This has limited most functional analyses to only a few well-represented fossil species. This paper introduces a method to characterize and compare worn occlusal morphology in primates using laser scanning and geographic information systems technologies. A study of variably worn chimpanzee and gorilla molars indicates that differences between these species in tooth shape remain consistent at given stages of wear. Although cusp slope decreases with wear in both taxa, angularity values remain unchanged. These results indicate that African ape teeth wear in a manner that keeps them mechanically efficient for fracturing specific foods. Studies of changes in tooth shape with wear add a new dimension to dental functional anatomy, and offer a more complete picture of dental-dietary adaptations. Also, given how rare unworn teeth are in the fossil record, the ability to include worn specimens in analyses opens the door to reconstructing the diets of many more extinct primate groups, allowing us to better understand the adaptive radiation of our order.

Robust hovering control of a PVTOL aircraft

Abstract: We study robust hovering control of vertical/short takeoff and landing (V/STOL) aircraft. For hovering control, we can model a V/STOL aircraft as a planar vertical takeoff and landing (PVTOL) aircraft. We use an optimal control approach to design a robust hovering control. The resulting control is a nonlinear state feedback whose robustness is demonstrated by numerical simulations.

Path analysis of rice yield and yield components as affected by seeding rate

Abstract: Understanding relationships among rice (Oryza sativa L.) yield and yield components (panicle density, filled grain per panicle, unfilled grain per panicle, and grain weight) is critical to utilizing these relationships effectively. Interrelationships among rice yield and yield components for direct-seeded rice cultural systems using path-coefficient analysis that describes a priori cause-and-effect relationships have not been shown. Our objective was to study direct-seeded rice yield and yield component relationships as affected by seeding rates using path-coefficient analysis. «Lemont», a semidwarf rice, was seeded at 43, 85, 128, 170, and 213 kg ha −1 in four environments between 1986 and 1988 (...)

Determinants and Consequences of Firm Information Technology Budgets

Abstract: For most firms, the information technology (IT) budget represents a major element in the overall firm budget, and IT budget decisions often have significant operational and strategic impacts on the business processes in the firm’s value chain. In this paper we use a large unique data set to examine the extent to which IT budgets are affected by environmental, organizational, and technological circumstances. We find that our cross-sectional model explains substantial variance in IT budgets, which indicates that contingent environmental, organizational, and technological factors affect managers’ budget decisions. We then examine the extent to which these IT budget levels are related to future firm performance, measured using both broad financial accounting measures, such as operating profit margins and return on assets, and market returns. We find that IT budget levels are positively associated with subsequent firm performance and shareholder returns. We further suggest that IT’s aggregate effect ...