366 research outputs found

    Results of the 1997 Illinois Deer Hunter Survey

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    Administrative ReportReport issued on: July 17, 200

    Parasitoid response to concentration of herbivore food plants: fording and leaving plants. Ecology

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    JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact [email protected]. Abstract. We hypothesized that a parasitoid of an herbivore would be attracted to large rather than small patches of plants that provide food for the herbivore. We conducted experiments to determine whether such parasitoids would be more likely to find and/or less likely to leave large patches of their victims' host plants. We also examined whether prey density (independent of patch size) affects plant finding or leaving. These aspects of plant foraging behavior were examined for Diaeretiella rapae (Hymenoptera: Aphidiidae), a parasitoid wasp that attacks aphids primarily on cruciferous plants. Ecological Society of America Arrival rates of naturally occurring D. rapae in artificial patches of 5, 10, 20, and 40 potted collard plants were measured in a field experiment. There was no patch-size effect (plants in larger patches were not more likely to be found), and plants with aphids were not more likely to be found than aphid-free plants. Furthermore, there was no dosage response to water bowl traps baited with chemical plant attractant placed in the same field. Leaving rates were measured in a greenhouse experiment using dispersal cages containing 1, 4, or 16 plants and 0, 10, or 100 aphids. Leaving rate decreased in larger patches independently of aphid density, which also affected leaving rate. We conclude that plant leaving may be equally or more important than plant finding in determining abundance of D. rapae in patches of crucifers. The significance of this result is discussed

    Partial charge transfer and absence of induced magnetization in EuS(111)/Bi2Se3 heterostructures

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    Heterostructures made from topological and magnetic insulators promise to form excellent platforms for new electronic and spintronic functionalities mediated by interfacial effects. We report the results of a first-principles density functional theory study of the geometric, electronic structure, and magnetic properties of the EuS(111)/Bi2Se3 interface, including van der Waals and relativistic spin-orbit effects. In contrast to previous theoretical studies, we find no appreciable magnetic anisotropy in such a heterostructure. We also do not see additional induced magnetization at the interface or the magnetic proximity effect on the topological states. This is due to the localized nature of Eu moments and because of a partial charge transfer of ∼0.5 electron from Eu to Se. The formation of the surface dipole shifts the Dirac cone about 0.4 eV below the chemical potential, and the associated electrostatic screening moves the topological state from the first to the second quintuple layer of Bi2Se3

    Equation of motion coupled cluster methods for electron attachment and ionization potential in polyacenes

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    Polyacenes have attracted considerable attention due to their various applications in organic optoelectronic materials. This study focuses on linear polyacenes and their electron affinity (EA) and ionization potential (IP) properties. We have employed our recent implementation of EA/IP equation of motion coupled cluster singles and doubles (EA/IP-EOMCCSD) methods which are accurate, computationally efficient and are capable of treating large systems employing reasonable basis sets size. The EA/IP results obtained for naphthalene, anthracene, tetracene, pentacene, hexacene and heptacene are in a good agreement with experiment. Comparison between quality of excitation energies obtained from IP-EOMCCSD and EE-EOMCCSD formalisms were also studied

    Energy Performance of Advanced Reboiled and Flash Stripper Configurations for CO2 Capture Using Monoethanolamine

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    CO2 capture by absorption using amine solvents has the potential to significantly reduce the CO2 emissions from fossil-fuel power plants. One of the major costs of this technology is the energy required for solvent regeneration. Complex process configurations claim to have promising potential to reduce the energy required for solvent regeneration. In this work, the effect of flow-sheet complexity is explored by studying two advanced stripping flow sheets: an advanced flash stripper and an advanced reboiled stripper. Both advanced configurations recover the stripping steam heat by means of a heat integration comprised of cold- and warm-rich solvent bypasses. The advanced configurations are simulated and optimized in Aspen Plus V.8.4 using 7 m monoethanolamine (MEA) with lean loading from 0.15 to 0.38 (mol CO2/mol MEA). The rich loading associated with each lean loading is determined by simulating the absorber providing 90% capture from flue gas with 4 mol % CO2, typical of a natural gas-fired turbine. The results are compared to a simple stripper in terms of total equivalent work. Both the advanced reboiled stripper and the advanced flash stripper require 12% less equivalent work than a simple stripper. The associated cold-rich and warm-rich bypasses for the optimum cases are, respectively, 20% and 50% for the advanced reboiled stripper and 15% and 35% for the advanced flash stripper

    State laws on tobacco control – United States, 1998

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    Problem/Condition: State laws addressing tobacco use, the leading preventable cause of death in the United States, are summarized. Laws address smoke-free indoor air, minors’ access to tobacco products, advertising of tobacco products, and excise taxes on tobacco products. Reporting Period Covered: Legislation effective through December 31, 1998. Description of System: CDC identified laws addressing tobacco control by using an on-line legal research database. CDC’s findings were verified with the National Cancer Institute’s State Cancer Legislative Database. Results: Since a previous surveillance summary on state tobacco-control laws published in November 1995 (covering legislation effective through June 30, 1995), several states have enacted new restrictions or strengthened existing legislation that addresses smoke-free indoor air, minors’ access to tobacco, tobacco advertising, and tobacco taxes. Five states strengthened their smoke-free indoor air legislation. All states and Washington, D.C., continued to prohibit the sale and distribution of tobacco products to minors; however, 21 states expanded minors’ access laws by designating enforcement authorities, adding license suspension or revocation for sale to minors, or requiring signage. Since the 1995 report, eight additional states (a total of 19 states and Washington, D.C.) now ban vending machines from areas accessible to minors. Thirteen states restrict advertising of tobacco products, an increase of four states since the 1995 report. Although the number of states that tax cigarettes and smokeless tobacco did not change, 13 states increased excise taxes on cigarettes, and five states increased excise taxes on smokeless tobacco products. The average state excise tax on cigarettes is 38.9¢ per pack, an increase of 7.4¢ compared with the average tax in the 1995 report. Interpretation: State laws addressing tobacco control vary in relation to restrictiveness, enforcement and penalties, preemptions, and exceptions. Actions Taken: The data summarizing state tobacco-control laws are available through CDC’s State Tobacco Activities Tracking and Evaluation (STATE) System*; the laws are collected and updated every quarter. The STATE System also contains statespecific data on the prevalence of tobacco use, tobacco-related deaths, and the costs of tobacco use. Information from the STATE System is available for use by policy makers at the state and local levels to plan and implement initiatives to prevent and reduce tobacco use. In addition, CDC is using this information to assess the ongoing impact of tobacco-control programs and policies on tobacco use

    Annihilation and Control of Chiral Domain Walls with Magnetic Fields

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    The control of domain walls is central to nearly all magnetic technologies, particularly for information storage and spintronics. Creative attempts to increase storage density need to overcome volatility due to thermal fluctuations of nanoscopic domains and heating limitations. Topological defects, such as solitons, skyrmions, and merons, may be much less susceptible to fluctuations, owing to topological constraints, while also being controllable with low current densities. Here, we present the first evidence for soliton/soliton and soliton/antisoliton domain walls in the hexagonal chiral magnet Mn1/3NbS2 that respond asymmetrically to magnetic fields and exhibit pair-annihilation. This is important because it suggests the possibility of controlling the occurrence of soliton pairs and the use of small fields or small currents to control nanoscopic magnetic domains. Specifically, our data suggest that either soliton/soliton or soliton/antisoliton pairs can be stabilized by tuning the balance between intrinsic exchange interactions and long-range magnetostatics in restricted geometriesComment: 8 pages, 4 figure
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