Thermal Requirements for Emergence of Overwintered Sorghum Midge (Diptera: Cecidomyiidae)

Emergence of overwintered sorghum midges, Contarinia sorghicola (Coquillett), was monitored during 1979, 1980, and 1981. Differences in emergence times and distributions among years was a function of soil temperature and rainfall. A heat unit accumulation model incorporating a rainfall adjustment factor was developed which described adult emergence in the spring. Adult midges initiated emergence after accumulating 431 centigrade heat units (based on mean daily to-cm soil temperatures starting 1 April) above a threshold temperature of 14.8°C, whereas, 679 and 977 heat units were required for 50 and 95% emergence, respectively. Sorghum midges that overwintered in johnsongrass spikelets emerged after similar heat unit accumulations as midges that overwintered in sorghum spikelets. The time that midges initiated diapause one year had little effect on the timing or distribution of emergence the following spring. No midges terminated diapause and emerged as adults during the same season that diapause was initiated. Of the diapausing midges, 23% failed to emerge until the second spring and 2.6% emerged the third spring, but times and distributions of emergence were similar for all years

Caustics in turbulent aerosols

Networks of caustics can occur in the distribution of particles suspended in a randomly moving gas. These can facilitate coagulation of particles by bringing them into close proximity, even in cases where the trajectories do not coalesce. We show that the long-time morphology of these caustic patterns is determined by the Lyapunov exponents lambda_1, lambda_2 of the suspended particles, as well as the rate J at which particles encounter caustics. We develop a theory determining the quantities J, lambda_1, lambda_2 from the statistical properties of the gas flow, in the limit of short correlation times.Comment: 4 pages, 3 figure

G94-1210 Borers of Shade Trees and Ornamental Plants

This publication describes the important shade tree and ornamental borers in Nebraska and discusses their management. Nearly all shade trees are subject to borer attack. If damage is severe, young trees are likely to decline or die

NF96-269 Chiggers

This NebFact has information on chiggers

G94-1210 Borers of Shade Trees and Ornamental Plants

This publication describes the important shade tree and ornamental borers in Nebraska and discusses their management. Nearly all shade trees are subject to borer attack. If damage is severe, young trees are likely to decline or die

G92-1107 Elm Leaf Beetle

History, identification, and indoor and outdoor control of the elm leaf beetle are discussed. The elm leaf beetle is an imported pest, first found in the United States in 1834. Common throughout Nebraska, it is almost exclusively a pest of elms, including the American, Siberian and other varieties. Japanese Zelkova is also readily attacked. Adults (beetles) vary in color from yellow to olive green, and have a black stripe near the outside of each wing cover. They can be confused with other beetles of similar appearance (western corn rootworm, striped cucumber beetle), but they are distinctive in that they occur early in the season and have three dark spots on the body segment behind the head

Field emission properties of nano-composite carbon nitride films

A modified cathodic arc technique has been used to deposit carbon nitride thin films directly on n+ Si substrates. Transmission Electron Microscopy showed that clusters of fullerene-like nanoparticles are embedded in the deposited material. Field emission in vacuum from as-grown films starts at an electric field strength of 3.8 V/micron. When the films were etched in an HF:NH4F solution for ten minutes, the threshold field decreased to 2.6 V/micron. The role of the carbon nanoparticles in the field emission process and the influence of the chemical etching treatment are discussed.Comment: 22 pages, 8 figures, submitted to J. Vac. Sc. Techn.

Withdrawn Behavior in Preschool: Implications for Emotion Knowledge and Broader Emotional Competence

The present study investigated the respective roles of withdrawal, language, and context-inappropriate (CI) anger in the development of emotion knowledge (EK) among a subsample of 4 and 5 year-old preschoolers (n = 74). Measures included parent-reported withdrawn behavior, externalizing behavior, and CI anger, as well as child assessments of receptive language and EK. Ultimately, findings demonstrated that receptive language mediated the relationship between withdrawn behavior and situational EK. However, CI anger significantly interacted with receptive language, and, when incorporated into a second-stage moderated mediation analysis, moderate levels of CI anger rendered the indirect effect of withdrawn behavior on situational EK via receptive language insignificant. Cumulatively, these findings demonstrate a mechanism by which withdrawal may impact EK. They also indicate that such an effect may be attenuated in children with moderate levels of CI anger. Implications of these findings are discussed

Electron-electron interaction in carbon nanostructures

The electron-electron interaction in carbon nanostructures was studied. A new method which allows to determine the electron-electron interaction constant $\lambda_c$ from the analysis of quantum correction to the magnetic susceptibility and the magnetoresistance was developed. Three types of carbon materials: arc-produced multiwalled carbon nanotubes (arc-MWNTs), CVD-produced catalytic multiwalled carbon nanotubes (c-MWNTs) and pyrolytic carbon were used for investigation. We found that $\lambda_c$=0.2 for arc-MWNTs (before and after bromination treatment); $\lambda_c$ = 0.1 for pyrolytic graphite; $\lambda_c >$ 0 for c-MWNTs. We conclude that the curvature of graphene layers in carbon nanostructures leads to the increase of the electron-electron interaction constant $\lambda_c$.Comment: 12 pages, 18 figures, to be published in the Proceedings of the NATO Advanced Research Workshop on Electron Correlation in New Materials and Nanosystems, NATO Science Series II, Springer, 200