Data communication between data terminal equipment and the JPL administrative data base management system

Approaches to enabling an installed base of mixed data terminal equipment to access a data base management system designed to work with a specific terminal are discussed. The approach taken by the Jet Propulsion Laboratory is described. Background information on the Jet Propulsion Laboratory (JPL), its organization and a description of the Administrative Data Base Management System is included

Pseudemys texana

Number of Pages: 2Integrative BiologyGeological Science

Spatial and Temporal Trends of Deer Harvest and Deer-Vehicle Accidents in Ohio

Author Institution: Buckeye Valley High School ; USDA Forest Service, Delaware CountyWhite-tailed deer (Odocoileus virginianus} have been increasing dramatically in the eastern United States, with concomitant increases in impacts resulting from deer browsing and deer-vehicle collisions. In Ohio, the number of deer were estimated at near zero in 1940 to over 450,000 in 1995. We analyzed estimates of deer harvest and deer-vehicle collisions in 1995 for 88 counties in Ohio. These data were also related to county-level spatial data on the length of major highways, urban land, rural land, crop land, forest land, all land, and human population. The objectives of this study were to evaluate the spatial and temporal trends of white-tailed deer across Ohio and to relate these patterns to the formerly mentioned environmental and human variables. For 1995 data, positive relationships existed between the amount of urban land in the county versus the number of deer-vehicle collisions, the amount of forest land in the county versus the number of deer harvested, the human population of a county versus the number of deer-vehicle collisions, and the length of major highways in a county versus the number of deer-vehicle collisions. Negative relationships existed between the amount of crop land in a county versus the number of deer harvested, the amount of crop land versus the number of deer-vehicle collisions, and the amount of urban land versus the number of deer harvested. Nine counties, representing various levels of land-use and human population tendencies, were analyzed for historic trends in deer harvest (1985-1995) and deer-vehicle collisions (1988-1995); in each case, there were substantial rises over the previous decade. Extensions of the resulting regression lines show the possibility for continued increases in deervehicle collisions, especially those with a high human population and forest cover. The dramatic increases in deer populations can be attributed to increasing forest land in the state, more habitat of shrubby land, few predators, mild winters, and the deer's ability to adapt to human-inhabited environments

Coupling between a glacier and a soft bed: II Model results

The relation between the local effective pressure and shear stress on till beneath Storglaciären, Sweden, discussed in Iverson and others (1999), provides an empirical basis for studying the processes that control the strength of the ice/bed coupling. Particles in the bed that protrude into the glacier sole support shear stresses that are limited by either ploughing or the traditional sliding mechanisms. Model calculations, based on studies of cone penetration through fine-grained sediment and sliding theory, agree with the observed relation between shear stress and effective pressure if the water layer at the ice/bed interface is assumed to thicken rapidly as the effective pressure approaches zero. Studies of the hydraulics of linked cavities provide support for this assumption, if the mean thickness of the water layer reflects the extent of microcavity development at the interface. Comparison of the calculated shear stress with the ultimate strength of till suggests that bed deformation limits the shear stress on till beneath Storglaciären only at intermediate effective pressures; at very low effective pressures, like those inferred at the site of the tiltmeter discussed in Iverson and others (1999), and at sufficiently high effective pressures, ploughing and sliding should focus motion near the glacier sole. A calculation using parameter values appropriate for Ice Stream B, West Antarctica, suggests that ploughing may occur there at shear stresses not sufficient to deform the bed at depth. This conclusion is reinforced by the likelihood that pore pressures in excess of hydrostatic should develop down-glacier from ploughing particles, thereby weakening the bed near the glacier sole. However, given the apparent sensitivity of the ice/bed coupling to basal conditions that may be highly variable, any blanket assumption regarding the flow mechanism of ice masses on soft beds should probably be viewed with skepticism

The Role of Pioneering Species on the Reclamation of North Dakota Surface Mined Lands

Four reclaimed mined areas in western North Dakota ranging in age from one to four years since mining, along with a site from a native mixed grass prairie for comparison, were studied to quantify the early successional changes in floristic composition, soil chemistry and plant chemical composition. The mined sites had been contoured, topsoiled, fertilized, and seeded. However, analysis of the seed bank in topsoil showed that the most dominant colonizers immigrate after topsoiling. Of the 95 species encountered, Kochia scoparia was the most dominant in the first two years following mining. Kochia had relatively low densities 2 in the first year (50-80/m ), but were robust and attained heights 2 of 88 cm with a biomass of about 400 g/m . In the second year, the 2 plant densities increases to over 10,000/m but the height and 2 biomass were reduced to 15 cm and 90 g/m . However, during the third and fourth years Kochia density declined and was practically nonexistent by the fourth year, while the planted Agropyron grasses had concomitantly increased. Other pioneers like Amaranthus retroflexus, Chenopodium album, Helianthus annuus, Salsola spp., and Setaria spp. showed a less abrupt but similar decline. Chemical analysis of the soils over the same time period showed decreases in electrical conductivity (E.C.) and in the concentrations of Ca, Mg, Na, Li, Sr, and S04 (due to leaching), while organic matter (O.M.) increased. Field studies were conducted on the interspecific relations of the dominant species during early succession - Kochia, Salsola collina and Agropyron spp. It was found that Kochia and Salsola acted as nurse crops for several months during the first year of Agropyron spp. establishment, but then began to shade heavily by late July thus reducing grass tillering. Field and growth chamber experiments on the intraspecific relations of Kochia demonstrated that it conformed to the laws of reciprocal yield, self-thinning, and constant final yield. Autotoxicity in Kochia appears to be the main factor causing the decline in its density. A field experiment indicated that thinning dense second year Kochia stands to the density of first year stands did not alter the growth of Kochia, providing strong evidence for autotoxicity. Similarly, several growth chamber experiments demonstrated that small amounts of decaying Kochia leaves and especially roots were toxic to Kochia growth, but not Melilotus officinalis or Agropyron caninum. Chemical analysis of the soils and tissues indicated nutritional imbalances as shown by P/Zn and P/Mn ratios may be responsible for the autotoxicity. In addition to Kochia, a bioassay experiment showed allelochemics to be important in several other colonizing species. Results indicated that later stage species generally have greater toxicities than first year colonizers. An analysis of the seeds present in topsoils (a grazed area, an ungrazed area, and two stockpiles) indicated that seeds of the most prevalent colonizers were not present in the topsoil upon respreading but rather appeared by immigration from the surrounding areas. The grazed site had a seed density of over 7,700 seeds/m^ (of which 43% were from weedy species) and the ungrazed site had 3,900 seeds/m (of which 1/ were weeds); the stockpiles of topsoil had very low seed densities. Mowing of first year Kochia and Salsola just prior to seed set benefited the establishment of grasses, since Agropyron spp. produced over eight times greater biomass after mowing compared with Kochia which produced only one-fourth the biomass. Burning dead Kochia stems and seedlings in second year helped other weedy species; grass growth was impaired. Burning of a six year old reclaimed site resulted in significant reductions in soil water, standing dead biomass, and litter, and some differences in biomass of the species components; however, biomass of species of Agropyron increased whereas those of Stipa decreased by burning. Overall, no significant differences in total live biomass were recorded within two years after the burn

Bioprocesses

The application of remote sensing techniques to the study of eutrophication in natural waters and the location and characterization of fronts is considered. The specific problem to be studied is examined along with the feasibility and capabability of remote sensing techniques for each application

Dust storms on Mars: Considerations and simulations

Aeolian processes are important in modifying the surface of Mars at present, and appear to have been significant in the geological past. Aeolian activity includes local and global dust storms, the formation of erosional features such as yardangs and depositional features such as sand dunes, and the erosion of rock and soil. As a means of understanding aeolian processes on Mars, an investigation is in progress that includes laboratory simulations, field studies of earth analogs, and interpretation of spacecraft data. This report describes the Martian Surface Wind Tunnel, an experimental facility established at NASA-Ames Research Center, and presents some results of the general investigation. Experiments dealing with wind speeds and other conditions required for the initiation of particle movement on Mars are described and considerations are given to the resulting effectiveness of aeolian erosion