15,500 research outputs found
Annotated Checklist of the Pentatomidae (Heteroptera) of Connecticut
We provide town data for the Pentatomidae in Connecticut. Although this state has been much collected, most sampling has been limited to only a few lo- cations. Species newly recorded for Connecticut are: Halyomorpha halys (Stål), Hymenarcys nervosa (Say), Banasa euchlora Stål, B. sordida (Uhler), and Perillus bioculatus (Fabricius). Podisus neglectus (Westwood) may occur in the state. Other species found in neighboring states may eventually be found in Connecticut: Picromerus bidens (Linnaeus), Rhacognathus americanus Stål, Mcphersonarcys aequalis (Say), Thyanta custator custator (Fabricius), T. custator acerra McAtee, and Amaurochrous brevitylus (Barber and Sailer). We briefly analyze these data, recognizing some faunal elements. More collecting needs to be conducted in the state, so that distribution patterns outlined here can be more broadly understood, and so that species of potential conservation concern can be identified
Attack of \u3ci\u3eUrophora Quadrifasciata\u3c/i\u3e (Meig.) (Diiptera: Tephritidae) A Biological Control Agent for Spotted Knapweed (\u3ci\u3eCentaurea Maculosa\u3c/i\u3e Lamarck) and Diffuse Knapweed (\u3ci\u3eC. Diffusa\u3c/i\u3e Lamarck) (Asteraceae) by a Parasitoid, \u3ci\u3ePteromalus\u3c/i\u3e Sp. (Hymenoptera: Pteromalidae) in Michigan
Urophora quadrifasciata (Meig.) a seedhead fly released in North America for biological control of Centaurea maculosa and C. diffusa is parasitized by a Pteromalus sp. Parasitism up to 60% of U. quadrifasciata was found in samples of seed heads of C. maculosa and C. diffusa collected from 54 of the 59 counties sampled in Michigan and in one sample of C. maculosa seed heads from Hennepin County, Minnesota. Parasitism of U. quadrifasciata has rarely been reported
Dilettante, Venturesome, Tory and Crafts: Drivers of Performance Among Taxonomic Groups
Empirical research has failed to cumulate into a coherent taxonomy of small firms. This may be because the method adapted from biology by Bill McKelvey has almost never been adopted. His approach calls for extensive variables and a focused sample of organizations, contrary to most empirical studies, which are specialized. Comparing general and special purpose approaches, we find some of the latter have more explanatory power than others and that general purpose taxonomies have the greatest explanatory power. Examining performance, we find the types do not display significantly different levels of performance but they display highly varied drivers of performance
The Kinematic Composition of MgII Absorbers
The study of galaxy evolution using quasar absorption lines requires an
understanding of what components of galaxies and their surroundings are
contributing to the absorption in various transitions. This paper considers the
kinematic composition of the class of 0.4 < z < 1.0 MgII absorbers,
particularly addressing the question of what fraction of this absorption is
produced in halos and what fraction arises from galaxy disks. We design models
with various fractional contributions from radial infall of halo material and
from a rotating thick disk component. We generate synthetic spectra from lines
of sight through model galaxies and compare the resulting ensembles of MgII
profiles with the 0.4 < z < 1.0 sample observed with HIRES/Keck. We apply a
battery of statistical tests and find that pure disk and pure halo models can
be ruled out, but that various models with rotating disk and infall/halo
contributions can produce an ensemble that is nearly consistent with the data.
A discrepancy in all models that we considered requires the existence of a
kinematic component intermediate between halo and thick disk. The variety of
MgII profiles can be explained by the gas in disks and halos of galaxies not
very much different than galaxies in the local Universe.
In any one case there is considerable ambiguity in diagnosing the kinematic
composition of an absorber from the low ionization high resolution spectra
alone. Future data will allow galaxy morphologies, impact parameters, and
orientations, FeII/MgII of clouds, and the distribution of high ionization gas
to be incorporated into the kinematic analysis. Combining all these data will
permit a more accurate diagnosis of the physical conditions along the line of
sight through the absorbing galaxy.Comment: 34 pages including 14 postscript figures; Accepted by the
Astrophysical Journal; URL http://www.astro.psu.edu/users/cwc/pubs.htm
Producing approximate answers to database queries
We have designed and implemented a query processor, called APPROXIMATE, that makes approximate answers available if part of the database is unavailable or if there is not enough time to produce an exact answer. The accuracy of the approximate answers produced improves monotonically with the amount of data retrieved to produce the result. The exact answer is produced if all of the needed data are available and query processing is allowed to continue until completion. The monotone query processing algorithm of APPROXIMATE works within the standard relational algebra framework and can be implemented on a relational database system with little change to the relational architecture. We describe here the approximation semantics of APPROXIMATE that serves as the basis for meaningful approximations of both set-valued and single-valued queries. We show how APPROXIMATE is implemented to make effective use of semantic information, provided by an object-oriented view of the database, and describe the additional overhead required by APPROXIMATE
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