University of Nebraska Omaha

About: University of Nebraska Omaha is a education organization based out in Omaha, Nebraska, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 4526 authors who have published 8905 publications receiving 213914 citations. The organization is also known as: UNO & University of Omaha.

Bt crop effects on functional guilds of non-target arthropods: a meta-analysis.

Abstract: Background Uncertainty persists over the environmental effects of genetically-engineered crops that produce the insecticidal Cry proteins of Bacillus thuringiensis (Bt). We performed meta-analyses on a modified public database to synthesize current knowledge about the effects of Bt cotton, maize and potato on the abundance and interactions of arthropod non-target functional guilds. Methodology/Principal Findings We compared the abundance of predators, parasitoids, omnivores, detritivores and herbivores under scenarios in which neither, only the non-Bt crops, or both Bt and non-Bt crops received insecticide treatments. Predators were less abundant in Bt cotton compared to unsprayed non-Bt controls. As expected, fewer specialist parasitoids of the target pest occurred in Bt maize fields compared to unsprayed non-Bt controls, but no significant reduction was detected for other parasitoids. Numbers of predators and herbivores were higher in Bt crops compared to sprayed non-Bt controls, and type of insecticide influenced the magnitude of the difference. Omnivores and detritivores were more abundant in insecticide-treated controls and for the latter guild this was associated with reductions of their predators in sprayed non-Bt maize. No differences in abundance were found when both Bt and non-Bt crops were sprayed. Predator-to-prey ratios were unchanged by either Bt crops or the use of insecticides; ratios were higher in Bt maize relative to the sprayed non-Bt control. Conclusions/Significance Overall, we find no uniform effects of Bt cotton, maize and potato on the functional guilds of non-target arthropods. Use of and type of insecticides influenced the magnitude and direction of effects; insecticde effects were much larger than those of Bt crops. These meta-analyses underscore the importance of using controls not only to isolate the effects of a Bt crop per se but also to reflect the replacement of existing agricultural practices. Results will provide researchers with information to design more robust experiments and will inform the decisions of diverse stakeholders regarding the safety of transgenic insecticidal crops.

Rules of Crowdsourcing: Models, Issues, and Systems of Control

Abstract: In this paper, we first provide a practical yet rigorous definition of crowdsourcing that incorporates “crowds,” outsourcing, and social web technologies. We then analyze 103 well-known crowdsourcing websites using content analysis methods and the hermeneutic reading principle. Based on our analysis, we develop a “taxonomic theory” of crowdsourcing by organizing the empirical variants in nine distinct forms of crowdsourcing models. We also discuss key issues and directions, concentrating on the notion of managerial control systems.

Explaining and Predicting the Impact of Branding Alliances and Website Quality on Initial Consumer Trust of E-Commerce Websites

Abstract: Trust is a crucial factor in e-commerce. However, consumers are less likely to trust unknown websites. This study explores how less-familiar e-commerce websites can use branding alliances and website quality to increase the likelihood of initial consumer trust. We use the associative network model of memory to explain brand knowledge and to show how the mere exposure effect can be leveraged to improve a website's brand image. We also extend information integration theory to explain how branding alliances are able to increase initial trust and transfer positive effects to websites. Testing of our model shows that the most important constructs for increasing initial trust in our experimental context are branding and website quality. Finally, we discuss future research ideas, limitations, implications, and ideas for practitioners.

Quasiparticle energies and excitonic effects of the two-dimensional carbon allotrope graphdiyne: Theory and experiment

Abstract: We report the electronic structure and optical properties of the recently synthesized stable two-dimensional carbon allotrope graphdiyne based on first-principles calculations and experimental optical spectrum. Due to the enhanced Coulomb interaction in reduced dimensionality, the band gap of graphdiyne increases to 1.10 eV within the $GW$ many-body theory from a value of 0.44 eV within the density functional theory. The optical absorption is dominated by excitonic effects with a remarkable electron-hole binding energy of over 0.55 eV within the $GW$--Bethe-Salpeter equation calculation. Experimental optical absorption of graphdiyne films is performed, and comparison with the theoretical calculations is analyzed in detail.