19,785 research outputs found
A Bait Attractant Study of the Nitidulidae (Coleoptera) at Shawnee State Forest in Southern Ohio
Four baits were tested for efficacy in attracting sap beetles (Nitidulidae) at two sites in the Shawnee State Forest over two collection periods in 1992. Species taken were categorized into three groups: abundant, moderate, and uncommon. At Site 1, nitidulids displayed a strong preference for whole wheat bread dough, followed by fermenting brown sugar, and fermenting malt/molasses solution, and vinegar, respectively. Site 2 collections showed a similar trend to Site 1, but the order of preference was switched for brown sugar and malt/molasses solution. Of the 20 species collected, six species were abundant, seven species were moderate, and seven species were locally uncommon
A Migration Study of \u3ci\u3eStelidota Geminata\u3c/i\u3e (Coleoptera: Nitidulidae)
The strawberry sap beetle, Stelidota geminata (Say), is a major pest of strawberries in the northeastern United States. Further knowledge of the migratory habits of this insect pest can enhance the effectiveness of pest management strategies. This nitidulid was shown to migrate from its overwintering sites to one of its primary reproductive sites, strawberry fields, in late May. The beetle population peaked in the third week in July, 1993 in the strawberry field and then gradually declined. In 1994, the peak, as well as the total population, was much greater than in 1993. Furthermore, S. geminata was concentrated in the transition areas surrounding the strawberry fields prior to the ripening of the fruit
Hadronic production of a Higgs boson and two jets at next-to-leading order
We perform an update of the next-to-leading order calculation of the rate for
Higgs boson production in association with two jets. Our new calculation
incorporates the full analytic result for the one-loop virtual amplitude. This
new theoretical information allows us to construct a code including the decay
of the Higgs boson without incurring a prohibitive penalty in computer running
time. Results are presented for the Tevatron, where implications for the Higgs
search are sketched, and also for a range of scenarios at the LHC.Comment: 16 pages, 4 figure
Analysis of Rapidity Gap Cuts in Diffractive DIS
The requirement of a large pseudo-rapidity gap to select diffractive DIS
events at HERA restricts the kinematically accessible region of phase space for
a significant range of , and \xpom. Consequences of this include
a breakdown of \xpom-factorization in large rapidity gap diffractive samples
and an enhancement in the relative contribution of quark-antiquark-gluon
processes over dijet processes in the diffractive DIS sample.Comment: LaTeX, 3 pages, 2 figures in PS files, uses npb.sty. Contribution to
the Proceedings of the 7th International Workshop on Deep Inelastic
Scattering and QCD, DIS99, DESY-Zeuthen, April 1999; Nucl. Phys. B (Proc.
Suppl.
Probing the Structure of the Pomeron
We suggest that the pseudo-rapidity cut dependence of diffractive deep-inelastic scattering events at HERA may provide a sensitive test of models of diffraction. A comparison with the experimental cross section shows that the Donnachie-Landshoff model and a simple two-gluon exchange model of the pomeron model are disfavoured. However a model with a direct coupling of the pomeron to quarks is viable for a harder quark--pomeron form factor, as is a model based on the leading-twist operator contribution. We also consider a direct-coupling scalar pomeron model. We comment on the implications of these results for the determination of the partonic structure of the pomeron.We suggest that the pseudo-rapidity cut dependence of diffractive deep-inelastic scattering events at HERA may provide a sensitive test of models of diffraction. A comparison with the experimental cross section shows that the Donnachie-Landshoff model and a simple two-gluon exchange model of the pomeron model are disfavoured. However a model with a direct coupling of the pomeron to quarks is viable for a harder quark--pomeron form factor, as is a model based on the leading-twist operator contribution. We also consider a direct-coupling scalar pomeron model. We comment on the implications of these results for the determination of the partonic structure of the pomeron
Jet photoproduction at HERA
We compute various kinematical distributions for one-jet and two-jet
inclusive photoproduction at HERA. Our results are accurate to next-to-leading
order in QCD. We use the subtraction method for the cancellation of infrared
singularities. We perform a thorough study of the reliability of QCD
predictions; in particular, we consider the scale dependence of our results and
discuss the cases when the perturbative expansion might break down. We also
deal with the problem of the experimental definition of the pointlike and
hadronic components of the incident photon, and briefly discuss the sensitivity
of QCD predictions upon the input parameters of the calculation, like
and the parton densities.Comment: 26 pages Latex, uses epsfig.sty, 24 eps figures include
On the Continuous Formation of Field Spheroidal Galaxies in Hierarchical Models of Structure Formation
We re-examine the assembly history of field spheroidals as a potentially
powerful discriminant of galaxy formation models. Whereas monolithic collapse
and hierarchical, merger-driven, models suggest radically different histories
for these galaxies, neither the theoretical predictions nor the observational
data for field galaxies have been sufficiently reliable for precise conclusions
to be drawn. A major difficulty in interpreting the observations, reviewed
here, concerns the taxonomic definition of spheroidals in merger-based models.
Using quantitative measures of recent star formation activity drawn from the
internal properties of a sample of distant field galaxies in the Hubble Deep
Fields, we undertake a new analysis to assess the continuous formation of
spheroidal galaxies. Whereas abundances and redshift distributions of modelled
spheroidals are fairly insensitive to their formation path, we demonstrate that
the distribution and amount of blue light arising from recent mergers provides
a more sensitive approach. With the limited resolved data currently available,
the rate of mass assembly implied by the observed colour inhomogeneities is
compared to that expected in popular Lambda-dominated cold dark matter models
of structure formation. These models produce as many highly inhomogeneous
spheroidals as observed, but underpredict the proportion of homogeneous,
passive objects. We conclude that colour inhomogeneities, particularly when
combined with spectroscopic diagnostics for large, representative samples of
field spheroidals, will be a more valuable test of their physical assembly
history than basic source counts and redshift distributions. Securing such data
should be a high priority for the Advanced Camera for Surveys on Hubble Space
Telescope.Comment: 14 pages, 7 figures, submitted to MNRA
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