9,490 research outputs found
A study of alteration associated with uranium occurrences in sandstone and its detection by remote sensing methods, volume 2
This document contains tabular and graphic data for volume 1
Detection and mapping of hydrothermally altered rocks in the vicinity of the comstock lode, Virginia Range, Nevada, using enhanced LANDSAT images
The author has identified the following significant results. LANDSAT images enhanced by the band-ratioing method can be used for reconnaissance alteration mapping in moderately heavily vegetated semiarid terrain as well as in sparsely vegetated to semiarid terrain where the technique was originally developed. Significant vegetation cover in a scene, however, requires the use of MSS ratios 4/5, 4/6, and 6/7 rather than 4/5, 5/6, and 6/7, and requires careful interpretation of the results. Supplemental information suitable to vegetation identification and cover estimates, such as standard LANDSAT false-color composites and low altitude aerial photographs of selected areas is desirable
Geometry of Valley Growth
Although amphitheater-shaped valley heads can be cut by groundwater flows
emerging from springs, recent geological evidence suggests that other processes
may also produce similar features, thus confounding the interpretations of such
valley heads on Earth and Mars. To better understand the origin of this
topographic form we combine field observations, laboratory experiments,
analysis of a high-resolution topographic map, and mathematical theory to
quantitatively characterize a class of physical phenomena that produce
amphitheater-shaped heads. The resulting geometric growth equation accurately
predicts the shape of decimeter-wide channels in laboratory experiments,
100-meter wide valleys in Florida and Idaho, and kilometer wide valleys on
Mars. We find that whenever the processes shaping a landscape favor the growth
of sharply protruding features, channels develop amphitheater-shaped heads with
an aspect ratio of pi
Higher Order Methods for Simulations on Quantum Computers
To efficiently implement many-qubit gates for use in quantum simulations on
quantum computers we develop and present methods reexpressing exp[-i (H_1 + H_2
+ ...) \Delta t] as a product of factors exp[-i H_1 \Delta t], exp[-i H_2
\Delta t], ... which is accurate to 3rd or 4th order in \Delta t. The methods
we derive are an extended form of symplectic method and can also be used for
the integration of classical Hamiltonians on classical computers. We derive
both integral and irrational methods, and find the most efficient methods in
both cases.Comment: 21 pages, Latex, one figur
Embedding right-angled Artin groups into graph braid groups
We construct an embedding of any right-angled Artin group defined
by a graph into a graph braid group. The number of strands required
for the braid group is equal to the chromatic number of . This
construction yields an example of a hyperbolic surface subgroup embedded in a
two strand planar graph braid group.Comment: 8 pages. Final version, appears in Geometriae Dedicata
The detection of geothermal areas from Skylab thermal data
Skylab-4 X-5 thermal data of the geysers area was analyzed to determine the feasibility of using midday Skylab images to detect geothermal areas. The hottest ground areas indicated on the Skylab image corresponded to south-facing barren or sparsely vegetated slopes. A geothermal area approximately 15 by 30 m coincided with one of the hottest areas indicated by Skylab. This area could not be unambiguously distinguished from the other areas which are believed to be hotter than their surroundings as a result of their topography, and micrometeorological conditions. A simple modification of a previous thermal model was performed and the predicted temperatures for the hottest slopes using representative values was in general agreement with the observed data. It is concluded that data from a single midday Skylab pass cannot be used to locate geothermal areas
On-line ostracism affects children differently from adolescents and adults
This research examines adults', and for the first time, children's and adolescents' reaction to being ostracized and included, using an on-line game, 'Cyberball' with same and opposite sex players. Ostracism strongly threatened four primary needs (esteem, belonging, meaning, and control) and lowered mood among 8- to 9-year-olds, 13- to 14-year-olds, and adults. However, it did so in different ways. Ostracism threatened self-esteem needs more among 8- to 9-year-olds than older participants. Among 13- to 14-year-olds, ostracism threatened belonging more than other needs. Belonging was threatened most when ostracism was participants' first experience in the game. Moreover, when participants had been included beforehand, ostracism threatened meaning needs most strongly. Gender of other players had no effect. Practical and developmental implications for social inclusion and on-line experiences among children and young people are discussed
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