14 research outputs found
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United States Geological Survey Report 248
Abstract: Pitchblende was discovered in July 1951 in the Alma mining district, Park County, Colo0 , by the U0 S. Geological Survey acting on behalf of the U. So Atomic Energy Commission. The pitchblende is associated with Tertiary veins of three different geologic environments: 1) veins in pre-Cambrian rocks, 2) the London vein system the footwall block of the London fault, and 3) veins in a mineralized area east of the Cooper Gulch fault. Pitchblende is probably not associated with silver-lead replacement deposits in dolomite. Secondary uranium minerals, as yet undetermined, are associated with pitchblende on two London vein system mine dumps, and occur in oxidized vein material.Lfrom dumps of mines in the other environments. Although none of the known occurrences are of commercial importance, the Alma district is considered a moderately favorable area in which to prospect for uranium ore, because twenty-four of the forty-three localities examined show anomalous radioactivity; samples from anomalously radioactive localities, which include mine dumps and some underground workings, have uranium contents ranging from 0.001 to l.66 percent
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United States Geological Survey Reports
Report discussing the results of a six-week geological investigation of 271 prospect pits, mine dumps, and mine workings in the Sugar Loaf -St. Kevin mining districts of Lake County, Colorado during 1951. The objective of the investigation was to determine the presence of radioactive materials
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United States Geological Survey Report 218
From page 3: A metallogenic province containing thorium in veins in pre-Cambrian rocks along the western slope of the Wet Mountains, Colo. found by the Reconnaissance Group of the U. S. Geological Survey during the summer of 1950,was revealed by the discovery during fiscal-years 1951-1952 of seventeen radioactive deposits scattered along a north-northwest linear distance of twenty miles. All the thorium occurrences were found within terrain that has never been geologically mapped. Three of the most promising localities were mapped at 1:1,200, and a diamond-drilling program was conducted at Haputa ranch
Long latency of evoked quantal transmitter release from somata of locus coeruleus neurons in rat pontine slices
The locus coeruleus (LC) harbors a compact group of noradrenergic cell bodies projecting to virtually all parts of the central nervous system. By using combined measurements of amperometry and patch-clamp, quantal vesicle release of noradrenaline (NA) was detected as amperometric spikes, after depolarization of the LC neurons. After a pulse depolarization, the average latency of amperometric spikes was 1,870 ms, whereas the latency of glutamate-mediated excitatory postsynaptic currents was 1.6 ms. A substantial fraction of the depolarization-induced amperometric spikes originated from the somata. In contrast to glutamate-mediated excitatory postsynaptic currents, NA secretion was strongly modulated by the action potential frequency (0.5–50 Hz). Somatodendritic NA release from LC upon enhanced cell activity produced autoinhibition of firing and of NA release. We conclude that, in contrast to classic synaptic transmission, quantal NA release from LC somata is characterized by a number of distinct properties, including long latency and high sensitivity to action potential frequency