31,695 research outputs found

    Seasonal Flight Patterns of Miridae (Hemiptera) in a Southern Illinois Black Walnut Plantation

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    The seasonal flight patterns of 92 species of Miridae collected in window traps in a southern Illinois black walnut plantation are compared with similar data from a North Carolina black walnut plantation. Flying height distributions and seasonal flight activities of Amblytylus nasutus, Deraeocoris nebulosus, Leptopterna dolabrata, Lopidea heidemanni, Lygus lineolaris, and Plagiognathus politus are considered in detail. Six species are newly recorded for Illinois

    Carbocations and the Complex Flavor and Bouquet of Wine: Mechanistic Aspects of Terpene Biosynthesis in Wine Grapes.

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    Computational chemistry approaches for studying the formation of terpenes/terpenoids in wines are presented, using five particular terpenes/terpenoids (1,8-cineole, α-ylangene, botrydial, rotundone, and the wine lactone), volatile compounds (or their precursors) found in wine and/or wine grapes, as representative examples. Through these examples, we show how modern computational quantum chemistry can be employed as an effective tool for assessing the validity of proposed mechanisms for terpene/terpenoid formation

    ELSA: An Integrated, Semi-Automated Nebular Abundance Package

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    We present ELSA, a new modular software package, written in C, to analyze and manage spectroscopic data from emission-line objects. In addition to calculating plasma diagnostics and abundances from nebular emission lines, the software provides a number of convenient features including the ability to ingest logs produced by IRAF's splot task, to semi-automatically merge spectra in different wavelength ranges, and to automatically generate various data tables in machine-readable or LaTeX format. ELSA features a highly sophisticated interstellar reddening correction scheme that takes into account temperature and density effects as well as He II contamination of the hydrogen Balmer lines. Abundance calculations are performed using a 5-level atom approximation with recent atomic data, based on R. Henry's ABUN program. Improvements planned in the near future include use of a three-region ionization model, similar to IRAF's nebular package, error propagation, and the addition of ultraviolet and infrared line analysis capability. Detailed documentation for all aspects of ELSA are available at http://www.williams.edu/Astronomy/research/PN .Comment: 2 pages, contributed paper, IAU Symp. 234, Planetary Nebulae in Our Galaxy and Beyon

    The stellar populations of spiral disks.II Measuring and modeling the radial distribution of absorption spectral indices

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    The radial distributions of the Mg2 and Fe5270 Lick spectral indices have been measured to large radial distances on the disks of NGC 4303 and NGC 4535 using an imaging technique based on interference filters. These data, added to those of NGC 4321 previously published in Paper I of this series are used to constraint chemical (multiphase) evolutionary models for these galaxies. Because the integrated light of a stellar disk is a time average over the history of the galaxy weighted by the star formation rate, these constraints complement the information on chemical gradients provided by the study of HII regions which, by themselves, can only provide the alpha-elements abundance accumulate over the life of the galaxy. The agreement between the observations and the model predictions shown here lends confidence to the models which are then used to describe the time evolution of galaxy parameters such as star formation rates, chemical gradients, and gradients in the mean age of the stellar population.Comment: to be published in Astrophysical Journa
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