1,899 research outputs found
A Solvable Mixed Charge Ensemble on the Line: Global Results
We consider an ensemble of interacting charged particles on the line
consisting of two species of particles with charge ratio 2 : 1 in the presence
of the harmonic oscillator potential. The system is assumed to be at
temperature corresponding to \beta = 1 and the sum of the charges is fixed. We
investigate the distribution of the number as well as the spatial density of
each species of particle in the limit as the total charge increases to \infty.
These results will follow from the fact that the system of particles forms a
Pfaffian point process. We produce the skew-orthogonal polynomials necessary to
simplify the related matrix kernels.Comment: 29 pages, 2 figure
Effect of Negative Ions Upon Rates of Reaction of Zinc With Hydrochloric and Perchloric Acids
The rate of evolution of hydrogen by the action hydrochloric acid and perchloric acid on zinc was measured volumetrically as a function of various negative ion concentrations. Increasing zinc ion concentration retards the rate of the reaction. A four to one ratio of chloride to zinc ion reaccelerates the rate, suggesting the formation of Zn Cl4-- which removes the excess zinc ion from the reaction. Other complexing ions, thiocyanate, bromide and iodide ion, accelerate the reaction as does chloride. Sulfate, like perchlorate, has little effect. The results explain the fact that hydrochloric acid reacts with zinc at a higher rate than does perchloric acid of equal concentration and similar strength
Measurement and Compensation of Horizontal Crabbing at the Cornell Electron Storage Ring Test Accelerator
In storage rings, horizontal dispersion in the rf cavities introduces
horizontal-longitudinal (xz) coupling, contributing to beam tilt in the xz
plane. This coupling can be characterized by a "crabbing" dispersion term
{\zeta}a that appears in the normal mode decomposition of the 1-turn transfer
matrix. {\zeta}a is proportional to the rf cavity voltage and the horizontal
dispersion in the cavity. We report experiments at the Cornell Electron Storage
Ring Test Accelerator (CesrTA) where xz coupling was explored using three
lattices with distinct crabbing properties. We characterize the xz coupling for
each case by measuring the horizontal projection of the beam with a beam size
monitor. The three lattice configurations correspond to a) 16 mrad xz tilt at
the beam size monitor source point, b) compensation of the {\zeta}a introduced
by one of two pairs of RF cavities with the second, and c) zero dispersion in
RF cavities, eliminating {\zeta}a entirely. Additionally, intrabeam scattering
(IBS) is evident in our measurements of beam size vs. rf voltage.Comment: 5 figures, 10 page
Occurrence of the Old World bug Megacopta cribraria (Fabricius) (Heteroptera: Plataspidae) in Georgia: a serious home invader and potential legume pest
Specimens of Megacopta cribraria (Fabricius) were collected in northern Georgia in late October 2009, where they were invading homes in large numbers. This is the first known occurrence of this species and the family Plataspidae in the New World. Megacopta cribraria was previously known from Asia and Australia. A key is provided to separate Plataspidae from other families of Pentatomoidea in America North of Mexico. A diagnosis and figures are provided to facilitate recognition of M. cribraria. Reported host plants and other aspects of the biology of this species are reviewed. Megacopta cribraria is considered a pest of numerous legumes in Asia, has the potential to provide biological control of kudzu, Pueraria montana var. lobata (Willd.) Ohwi, (Fabaceae) and likely will continue to be a household pest in the vicinity of kudzu fields as well as become a pest of North American legume crops
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