University of Maine

About: University of Maine is a education organization based out in Orono, Maine, United States. It is known for research contribution in the topics: Population & Ice sheet. The organization has 8637 authors who have published 16932 publications receiving 590124 citations. The organization is also known as: University of Maine at Orono.

Toward a Substantive Definition of the Corporate Issue Construct: A Review and Synthesis of the Literature

Abstract: This article works toward a more meaningful answer to the question: What is a corporate issue? The article builds from existing literature in business strategy, public policy, and business and society. It synthesizes and integrates this literature and then expands on it. The result is a reformulated definition of the corporate issue construct that enhances theory building and research activities in the area of issues management.

Excited-State Interactions for [Au(CN)2-]n and [Ag(CN)2-]n Oligomers in Solution. Formation of Luminescent Gold−Gold Bonded Excimers and Exciplexes

Abstract: Solutions of K[Au(CN)(2)] and K[Ag(CN)(2)] in water and methanol exhibit strong photoluminescence. Aqueous solutions of K[Au(CN)(2)] at ambient temperature exhibit luminescence at concentration levels of > or =10(-2) M, while frozen methanol glasses (77 K) exhibit strong luminescence with concentrations as low as 10(-5) M. The corresponding concentration limits for K[Ag(CN)(2)] solutions are 10(-1) M at ambient temperature and 10(-4) M at 77 K. Systematic variations in concentration, solvent, temperature, and excitation wavelength tune the luminescence energy of both K[Au(CN)(2)] and K[Ag(CN)(2)] solutions by >15 x 10(3) cm(-1) in the UV-visible region. The luminescence bands have been individually assigned to *[Au(CN)(2)(-)](n) and *[Ag(CN)(2)(-)](n) excimers and exciplexes that differ in "n" and geometry. The luminescence of Au(I) compounds is related for the first time to Au-Au bonded excimers and exciplexes similar to those reported earlier for Ag(I) compounds. Fully optimized unrestricted open-shell MP2 calculations for the lowest-energy triplet excited state of staggered [Au(CN)(2)(-)](2) show the formation of a Au-Au sigma single bond (2.66 A) in the triplet excimer, compared to a weaker ground-state aurophilic bond (2.96 A). The corresponding frequency calculations revealed Au-Au Raman-active stretching frequencies at 89.8 and 165.7 cm(-1) associated with the ground state and lowest triplet excited state, respectively. The experimental evidence of the exciplex assignment includes the extremely large Stokes shifts and the structureless feature of the luminescence bands, which suggest very distorted excited states. Extended Huckel (EH) calculations for [M(CN)(2)(-)](n) and *[M(CN)(2)(-)](n) models (M = Au, Ag; n = 2, 3) indicate the formation of M-M bonds in the first excited electronic states. From the average EH values for staggered dimers and trimers, the excited-state Au-Au and Ag-Ag bond energies are predicted to be 104 and 112 kJ/mol, respectively. The corresponding bond energies in the ground state are 32 and 25 kJ/mol, respectively.

Upper ocean export of particulate organic carbon in the Arabian Sea derived from thorium-234

Abstract: Thorium-234 is used in the Arabian Sea as a tracer of sinking particle fluxes. Samples were collected from January to August 1995 on four cruises during the Northeast Monsoon, the Spring Intermonsoon and the mid- and late-Southwest Monsoon periods. In this study, 234Th activity distributions are used to quantify the 234Th flux on sinking particles, and the measured ratio of particulate organic carbon (POC) to particulate 234Th is used to convert from 234Th to POC export at 100 m. The calculated POC fluxes range from 25 mmols C m-2 d-1, and strong seasonal and spatial gradients are observed. The single largest feature is a basinwide export maximum associated with the late-SW Monsoon cruise when POC export rates are 17–28% of the observed primary production rates along the southern sampling line. During all other cruises, this export ratio is

The Role of Cover Crops in North American Cropping Systems

Abstract: SUMMARY The benefits of cover crops in cropping systems have long been recognized. Legumes have historically been used lo provide biologically fixed nitrogen to cash crops, and it has been shown that soil erosion can be slowed significantly with even minimal amounts of soil cover during vulnerable times of year. The role of cover crops in North American farming systems is expanding to include management of weeds, disease and pests, and overall enhancement of soil quality through organic matter enrichment, improved nutrient cycling and reduction of soil compaction. While the predominant temporal niche for cover crops in North America remains the winter, other opportunities in diverse cropping systems exist for cover crop inclusion, such as summer fallow, living mulches or full-year fallow crops. To date, the use of cover crops is constrained by economic, biological, and farm operational factors, but farmer education, continued research, and government policy changes can aid in overcoming existing barriers ...