A Proposed Fog Deposition Mechanism for the Formation of Salt Efflorescences in the Mpumalanga Highveld,Republic of South Africa

White efflorescences, representing evaporites that coat stubble grass vegetation, were observed in September 1991 on a farm in the Ermelo area, Mpumalanga highveld of the Republic of South Africa. Occurrences were in irregular patches. Investigation of the evaporites by means of X-ray diffraction, differential thermal analysis, scanning electron microscopy with EDX, and chemical analyses revealed the following minerals, presented in order of decreasing abundance: thenardite, bloedite, gypsum and kieserite. Accumulation of the salts, which are highly water soluble, probably occurred during the six dry winter months, suggesting a deposition rate of up to 11–15 g of thenardite m^-2 yr^-1. It is proposed that the efflorescences had formed by fog impaction on grass blades. They are, to the authors' knowledge, the first recorded evaporite deposits formed by atmospheric deposition.     

Continental drainage in north america during the phanerozoic from Nd isotopes

Neodymium (Nd) isotopic data show consistent patterns in the sources of sedimentary rocks in North America at a continental scale. Between 600 and 450 million years ago (Ma), ancient continental shield sources dominated. Around 450 Ma, detritus from the Caledonian-Appalachian mountains overwhelmed sediment from all older sources, and is documented over large areas of the southern, western, and northern margins of North America. This material continued to dominate the sediment supply until about 150 Ma, probably due to cannibalistic recycling of sedimentary rocks formed earlier. Around 150 Ma, the rising western Cordillera delivered new and different detritus to the sedimentary system.     

Canine GM2 gangliosidosis: morphological and biochemical analysis

Beta-hexosaminidase activity and the effects of ganglioside storage on neuronal function were examined in a German shorthair pointer (GSHP) with progressive neurodegenerative signs. Morphologic evidence of neuronal storage and massive accumulation of GM2 ganglioside were present. Beta-hexosaminidase activity in plasma, liver, kidney, and brain, assayed with use of unsulfated fluorogenic substrates, was normal. There was no pathologic accumulation or aberrant localization of phosphorylated neurofilaments in neurons. Activity of cortical neurotransmitter synthesizing enzymes, choline acetyltransferase, and glutamate decarboxylase was unaffected. Ligand binding to carrier sites for choline high affinity uptake identified with [3H]hemicholinium-3 was increased, whereas post-synaptic binding to muscarinic cholinergic ([3H]QNB) and gamma-aminobutyric acid receptors ([3H]muscimol) was reduced.     

Experimental transmission of Chlamydia psittaci to turkeys from wild birds

Wild birds were inoculated with Chlamydia psittaci to determine species that could be potential hosts and vectors in transmitting the agent to domestic turkeys. Infection occurred in turkeys exposed to starlings (Sturnus vulgaris), common grackles (Quiscalus quiscula), brown-headed cowbirds (Molothrus ater), and Inca doves (Cardafella inca). Mourning doves (Zenaidura macroura) shed the agent sparingly, but turkeys exposed to them did not become infected, These findings and knowledge of the habits of these various species are discussed. It was concluded that the Inca dove should be considered a potential source of turkey chlamydiosis in Texas. The species studied and other species not studied should be included in serologic surveys and surveillance studies attempting isolation of chlamydiae.     

Zodiacal dust and deep-sea sediments

The recent detection of radioactive Al(26) in marine sediments has led to the conclusion that it is brought into the earth's atmosphere by micrometeorites which have been exposed, in interplanetary space, to solar high-energy protons. The Al(26) method is not precise enough to yield directly a reliable value for the mass accretion rate to the earth to better than about 3 orders of magnitude, but is sufficiently accurate to allow a crucial decision between two widely differing of interplanetary dust which have been proposed to explain observations of the zodiacal light. The two models lead to Al(26) concentrations which would differ by about 5 orders of magnitude. Thus, the presence of Al(26) is consistent with the zodiacal dust model with particles of some tens of microns rather then with submicron particles. From this model a mass accretion to the earth then be calculated which is set at 1250 (upper limit, 2500; lower limit, 250) tons per day, or 2.8 x 10(-15) g/cm(2) sec, or 4.5 x 10(11) g over the earth per This value does not depend on the flux of the solar high-energy particles, which may be uncertain by an order of magnitude or more. The presence of Al(26) supports the idea that an important fraction of the dust is stony in composition material density, and thus eliminates some more exotic dust models, as such one consisting entirely of carbon grains. We may also conclude that the accreted dust particles have been in the solar system and exposed to protons from solar high-energy particles for a time interval which is greater than a significant of the Al(26) half-life (0.74 x 10(6) years).