Organic chemistry of cometary dust as derived from PUMA 1 data

Onboard the Halley Fly-By spacecrafts Vega 1, Vega 2, and Giotto were the dust impact mass spectrometers PUMA 1, PUMA 2, and PIA respectively. PUMA 1 was the most sensitive instrument among them. From its data the occurrence of masslines greater than 60 Daltons could be shown to be statistically significant. An analysis of these masslines lead to a scenario, which could explain the masslines as fragment ions from larger molecules which characterize the chemical nature of cometary organic matter as: (1) highly unsaturated hydrocarbons; (2) some of them containing oxygen; (3) less containing nitrogen; and (4) a few containing oxygen and nitrogen as heteroatoms. From the properties of the spectrometer, also some physical parameters of the dust particles could be inferred, such as their density and structure

A mid-latitude ozone model for the US standard atmosphere, 1975 (summary)

A mid-latitude, Northern-Hemisphere model of the daytime ozone distribution in the troposphere, stratosphere, and lower mesosphere was constructed. Data from rocket soundings in the latitude range 45 deg N + or - 15 deg, results of balloon soundings at altitudes from 41 to 47 deg N, and latitude gradients from satellite ozone observations were combined to produce estimates of the annual mean ozone concentration and its variability at heights to 72 km for an effective latitude of 45 deg N. The model is a revision, for heights above 26 km, of the tentative Mid-Latitude Ozone Model

Correlation of shock initiated and thermally initiated chemical reactions in a 1:1 atomic ratio nickel-silicon mixture

Shock initiated chemical reaction experiments have been performed on a 1:1 atomic ratio mixture of 20- to 45-µm nickel and –325 mesh crystalline silicon powders. It has been observed that no detectable or only minor surface reactions occur between the constituents until a thermal energy threshold is reached, above which the reaction goes to completion. The experiments show the energy difference between virtually no and full reaction is on the order of 5 percent. Differential scanning calorimetery (DSC) of statically pressed powders shows an exothermic reaction beginning at a temperature which decreases with decreasing porosity. Powder, shock compressed to just below the threshold energy, starts to react in the DSC at 621 °C while powder statically pressed to 23% porosity starts to react at about 30 °C higher. Tap density powder starts to react at 891 °C. The DSC reaction initiation temperature of the shock compressed but unreacted powder corresponds to a thermal energy in the powder of 382 J/g which agrees well with the thermal energy produced by a shock wave with the threshold energy (between 384 and 396 J/g). (Thermal energies referenced to 20 °C.) A sharp energy threshold and a direct correlation with DSC results indicates that the mean thermal energy determines whether or not the reaction will propagate in the elemental Ni+Si powder mixture rather than local, particle level conditions. From this it may be concluded that the reaction occurs on a time scale greater than the time constant for thermal diffusion into the particle interiors

Planting the Seeds for Public Health: How the Farm Bill Can Help Farmers to Produce and Distribute Healthy Foods

Analyzes provisions in the 2008 Farm Bill that impede farmers' production and strategic marketing of fruits and vegetables. Recommends policy changes to remove such barriers, improve consumer access to healthy foods, and help prevent childhood obesity

The formation of 3,6-diphenylpyridazine and 2,5-diphenylpyrrole from alpha-styryl azide

Formation of 3,6-diphenylpyridazine and 2,5- diphenylpyrrole from alpha-styryl azid

Acid catalyzed reactions of alpha and beta styryl azides

Acid degradation of alpha and beta styryl azide

"Valuing the Visual Disamenity of Offshore Wind Projects at Varying Distances from the Shore: An Application on the Delaware Shoreline"

Several offshore wind power projects are under consideration in the United States. A concern with any wind power project is the visual disamenity it may create. Using a stated preference choice model, we estimated the external costs to residents of the State of Delaware for offshore wind turbines located at different distances from the coast. The annual costs to inland residents was $19,$9, $1, and$0 (2006$) for turbines located at 1, 3.6, 6, and 9 miles offshore. The cost to residents living on the ocean was$80, $69,$35, and $27 for the same increments.Windfarms, View Disamenity, Valuation

Aerosol scattering of ultraviolet sunlight in the tropical maritime atmosphere

The effects of atmospheric aerosol scattering on the vertical profile of solar ultraviolet radiation are investigated. Measurements of diffuse and total ultraviolet radiation were made using a rocketborne optical sonde in the marine atmosphere of Antigua. During observations, the sun was at zenith. Vertical profiles of directly transmitted solar radiation were calculated by subtraction of the diffuse component from the total radiance. Using these values of direct downward solar UV-flux, the optical thickness of the atmosphere was derived as a function of altitude. Absorption by ozone was also considered. In the troposphere the values of observed optical thickness were in general equal to or lower than those expected theoretically from Rayleigh scattering alone. The measured radiation profiles were compared with those computed for a multiple scattering model atmosphere. Some computations regarding the interaction of UV-sunlight with maritime aerosols are presented