Electricity and weather modification I. A survey of scientific relationships

Ethereal, evanescent, elusive?these are adjectives a poet might use to describe the fragile stuff of clouds. They are accurate, and evocative, but still another adjective?electrified?may prove to be more important in the years immediately ahead. Workers in the fields of atmospheric electricity and cloud physics have accumulated sufficient evidence to suggest that electric fields, forces, and charges in the earth's lower atmosphere play a critical role?perhaps the critical role?in the development and behavior of clouds that produce precipitation. This in turn suggests that manipulation of the electrical properties of clouds may someday provide the long-sought key to modification of the weather by man.     

The IPCS Collaborative Study on Neurobehavioral Screening. I. Background and genesis

Numerous events over several years culminated in recognition of the need to explicitly evaluate the nervous system as a potential target for environmental chemicals. Based on recommendations from several international expert panels, the International Programme on Chemical Safety (IPCS) sponsored the Collaborative Study on Neurobehavioral Screening Methods. A Steering Committee was created to oversee the project, develop the testing protocol, recruit participating laboratories and review and analyze the data. The protocol specified the tests, the chemicals (supplied from a common source) and the exposure conditions (acute and repeated dosing). Test methods were based upon existing practices in toxicological screening as well as recent advances in neurotoxicity screening. Chemicals were selected to produce different profiles of neurobehavioral effects. Considerable latitude was afforded the participating laboratories in the choice of several key variables (e.g., strain of rat, testing device for motor activity assessment) that could potentially affect the results of the experiments. The approach therefore provided a standardized yet flexible protocol for evaluating the reproducibility of neurobehavioral screening data in diverse laboratory settings.     

Isomerization and Decomposition of Chloromethylacetylene

The isomerization and thermal decomposition of chloromethylacetylene (CMA) has been studied with two shock tube techniques. The first experiment (Jerusalem) utilizes single-pulse shock tube methods to measure the isomerization rate of CMA to chloroallene. In addition, equilibrium constants can be estimated at ∼1200 K. The second experiment (Argonne) monitors Cl-atom formation at temperatures above ∼1150 K. Absolute yield measurements have been performed over the 1200–1700 K range and indicate that two decomposition channels contribute to CMA destruction, namely, Cl fission and HCl elimination. The results show that the branching fraction between processes is temperature dependent. Therefore, direct Cl-atom fission is accompanied by molecular elimination, undoubtedly giving HCl and one or more isomers of C₃H₂. MP2 6–31G(d,p) ab initio electronic structure calculations have been used to determine vibration frequencies and moments of inertia for three C₃H₃Cl isomers. Using these quantities, the experimental equilibrium constants required that ΔH⁰₀(CH₂Cl–C≡CH ⇌ CHCl=C=CH₂) = −;0.24 kcal mole⁻¹. A potential energy surface pertinent to the present system has been constructed, and RRKM calculations have been carried out in order to explain the isomerization rates. The isomerization data can be explained with E₀ = 52.3 kcal mole⁻¹ and 〈ΔE_down〉 = 225 cm⁻¹. Subsequent semi-empirical Troe and RRKM-Gorin modeling of the Cl atom rate data require E₀ = (67.5 ± 0.5) kcal mole⁻¹ with a 〈ΔE_down〉 = (365 ± 90) cm⁻¹. This suggests a heat of formation for propargyl radicals of (79.0 ± 2.5) kcal mole⁻¹.     

The IPCS Collaborative Study on Neurobehavioral Screening Methods: II. Protocol design and testing procedures

This paper describes the development of the protocol for the International Programme on Chemical Safety (IPCS)-sponsored Collaborative Study on Neurobehavioral Screening Methods, including background on the methods and chemicals selected, as well as details concerning the conduct of the collaborative study, including proficiency testing, range-finding and main study. Participating laboratories in the collaborative study received training in the conduct and scoring of the behavioral tests and each laboratory received a video training film to train additional personnel as needed. Each of the eight laboratories that chose to participate in the study completed proficiency testing and assessed seven representative chemicals using a functional observational battery and automated motor activity assessment. The seven chemicals studied were acrylamide, bis-acrylamide, p,p'-DDT, lead acetate, parathion, toluene, and triethyl tin. Participants received coded samples of the chemicals from a common source. Each laboratory derived doses for single and repeated administration based on the determination of a within-laboratory acute "top dose." Animal strains were not standardized and laboratory conditions were standardized to a limited degree in order to judge the general utility and robustness of these procedures in a diversity of testing situations.     

Role of dentate gyrus cells in retention of a radial arm maze task and sensitivity of rats to cholinergic drugs.

Male rats that received bilateral injections of colchicine into 2 rostrocaudal sites showed relatively long-lasting alterations in a previously acquired radial arm maze task and specific destruction of dentate granule cells. Subsequent experiments with cholinergic drugs indicate that physostigmine or nicotine had no effect on number of errors made in the maze, although other signs of cholinergic or pharmacological activity were present. RS-86, an analog of arecoline, decreased errors in colchicine-treated Ss, but effects were associated with signs of parasympathetic overstimulation and behavioral sedation. Pretreatment with scopolamine increased errors in controls but had no effect in colchicine-treated Ss. Colchicine-treated Ss were less sensitive to the motor stimulant effect of scopolamine. Effects appeared to be associated with increased levels of choline acetyltransferase in the hippocampus and a down regulation of muscarinic postsynaptic receptors. Intradentate colchicine may destroy granule cells, leading to compensatory reinnervation of cholinergic nerve terminals having cell bodies in the septum. (PsycINFO Database Record (c) 2010 APA, all rights reserved)