5,447 research outputs found
Notes on injurious insects
Among the insects which have been particularly destructive the past season the wheat head army worm is conspicuous. Reports received from different parts of the state, besides numerous articles in state papers, indicate it in many parts of the state heretofore free from it. It is especially noticeable on account of the method in which it works, the worm attacking the heads of timothy and shelling out the seed. In this way it causes almost a total loss of the seed crop, and, since its work appears after the time when timothy is best cut for hay, it also causes a considerable, if not total, loss of the hay crop.
Most of the reports of its injuries this season have come from the northeastern portion of the state, especially in the line of counties from Dubuque west to the middle of the state, but in a general way the reports indicate damage in all of the northeastern counties. A few years ago loss of the same nature occurred in some of the southeastern counties, the loss in Jefferson county being estimated at something like 30,000 in Wayne county. Reports during that year, 1887, showed its presence in the counties of Adair, Appanoose, Davis, Clarke, Decatur, Des Moines, Henry, Jefferson, Lee, Lucas, Ringgold, Van Buren and Wayne
Moyal Quantum Mechanics: The Semiclassical Heisenberg Dynamics
The Moyal--Weyl description of quantum mechanics provides a comprehensive
phase space representation of dynamics. The Weyl symbol image of the Heisenberg
picture evolution operator is regular in . Its semiclassical expansion
`coefficients,' acting on symbols that represent observables, are simple,
globally defined differential operators constructed in terms of the classical
flow. Two methods of constructing this expansion are discussed. The first
introduces a cluster-graph expansion for the symbol of an exponentiated
operator, which extends Groenewold's formula for the Weyl product of symbols.
This Poisson bracket based cluster expansion determines the Jacobi equations
for the semiclassical expansion of `quantum trajectories.' Their Green function
solutions construct the regular asymptotic series for the
Heisenberg--Weyl evolution map. The second method directly substitutes such a
series into the Moyal equation of motion and determines the
coefficients recursively. The Heisenberg--Weyl description of evolution
involves no essential singularity in , no Hamilton--Jacobi equation to
solve for the action, and no multiple trajectories, caustics or Maslov indices.Comment: 50, MANIT-94-0
Plant Lice Infesting Grass Roots
During the fall of 1889 the senior author of this paper determined that a species of plant louse, infesting roots of annual grasses was identical with the Dogwood plant louse (Schizoneura corni Fabr.), carrying the work far enough to prove that the winged forms could be transferred from grass roots to dogwood, on which they colonized. As he found the root forms principally on annual grasses which were of no economic value, it was naturally a question of interest to determine whether they might affect forage plants. Furthermore, the occurrence of non-migratory forms on certain of the grasses examined, left some questions which it seemed very desirable to follow up
Notes on Aphididae
A list of the Aphididae of the State as far as collected was published in the proceedings of this Academy for 1890-91 as part of the catalogue of Iowa Hemiptera. It was known at the time to be very incomplete, but it was considered best to include only such species as had been actually observed. As the past season was favorable, especially during autumn, for collecting in this family, considerable more material has been added. We present, therefore, a supplemental list with notes on habits and references to host plants
Are the school prevention programmes - aimed at de-normalizing smoking among youths - beneficial in the long term? An example from the Smoke Free Class Competition in Italy
Tobacco smoking by young people is of great concern because it usually leads to regular smoking, nicotine addiction and quitting difficulties. Young people "hooked" by tobacco maintain the profits of the tobacco industry by replacing smokers who quit or die. If new generations could be tobacco-free, as supported by tobacco endgame strategies, the tobacco epidemic could end within decades. Smoking prevention programmes for teens are offered by schools with the aim to prevent or delay smoking onset. Among these, the Smoke Free Class Competition (SFC) was widely implemented in Europe. Its effectiveness yielded conflicting results, but it was only evaluated at short/medium term (6 - 18 months). The aim of this study is to evaluate its effectiveness after a longer follow-up (3 to 5 years) in order to allow enough time for the maturing of the students and the internalization of the experience and its contents. Fifteen classes were randomly sampled from two Italian high schools of Bologna province that regularly offered the SFC to first year students; 382 students (174 participating in the SFC and 208 controls) were retrospectively followed-up and provided their "smoking histories". At the end of their last year of school (after 5 years from the SFC), the percentage of students who stated that they were regular smokers was lower among the SFC students than in controls: 13.5% vs 32.9% (p=0.03). From the students' "smoking histories", statistically significant protective ORs were observed for SFC students at the end of 1st and 5th year: 0.42 (95% CI 0.19-0.93) and 0.32 (95% CI 0.11-0.91) respectively. Absence of smokers in the family was also a strongly statistically significant factor associated with being a non-smoker student. These results suggest that SFC may have a positive impact on lowering the prevalence of smoking in the long term (5 years)
Adaptive multigrid algorithm for the lattice Wilson-Dirac operator
We present an adaptive multigrid solver for application to the non-Hermitian
Wilson-Dirac system of QCD. The key components leading to the success of our
proposed algorithm are the use of an adaptive projection onto coarse grids that
preserves the near null space of the system matrix together with a simplified
form of the correction based on the so-called gamma_5-Hermitian symmetry of the
Dirac operator. We demonstrate that the algorithm nearly eliminates critical
slowing down in the chiral limit and that it has weak dependence on the lattice
volume
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