Plan for the uniform mapping of earth resources and environmental complexes from Skylab imagery. Assessment of natural vegetation, environmental, and crop analogs

The author has identified the following significant results. For interpreting a wide range of natural vegetation analogs, S-190A color infrared and the ERTS-1 color composite were consistently more useful than were conventional color or black and white photos. Color infrared was superior for five vegetation analogs while color was superior for only three. The errors in identification appeared to associate more with black and white single band images than with multiband color. For rice crop analogs, spectral and spatial discriminations both contribute to the usefulness of images for data collection. Tests and subjective analyses conducted in this study indicated that the spectral bands exploited in color infrared film were the most useful for agricultural crop analysis. Accuracy of crop identification on any single date of Skylab images was less than that of multidate analysis due to differences in crop calendar, cultural practices used, rice variety, planting date, planting method, water use, fertilization, disease, or mechanical problems

Group velocity study in hot Rb vapor with buffer gas

We study the behavior of the group velocity of light under conditions of electromagnetically induced transparency (EIT) in a Doppler broadened medium. Specifically, we show how the group delay (or group velocity) of probe and generated Stokes fields depends on the one-photon detuning of drive and probe fields. We find that for atoms in a buffer gas the group velocity decreases with positive one-photon detuning of the drive fields, and increases when the fields are red detuned. This dependence is counter-intuitive to what would be expected if the one-photon detuning resulted in an interaction of the light with the resonant velocity subgroup.Comment: 6 pages, 7 figure

Deuteron and proton NMR study of D₂, p-dichlorobenzene and 1,3,5-trichlorobenzene in bimesogenic liquid crystals with two nematic phases

The solutes dideuterium, 1,3,5-trichlorobenzene and p-dichlorobenzene (pdcb) are co-dissolved in a 61/39 wt% mixture of CBC9CB/5CB, a bimesogenic liquid crystal with two nematic phases. NMR spectra are collected for each solute. The local electric field gradient (FZZ) is obtained from the dideuterium spectrum. A double Maier-Saupe potential (MSMS) is used to rationalize the order parameters of pdcb. The liquid-crystal fields G₁ and G₂ are taken to be due to size and shape interactions and interactions between the solute molecular quadrupole and the mean FZZ of the medium. The FZZ’s obtained from D₂ and G₂ (from pdcb) are compared and discussed

Financial Market Runs

Our paper offers a minimalist model of a run on a financial market. The prime ingredient is that each risk-neutral investor fears having to liquidate after a run, but before prices can recover back to fundamental values. During the urn, only the risk-averse market-making sector is willing to absorb shares. To avoid having to possibly liquidate shares at the marginal post-run price in which case the market-making sector will already hold a lot of share inventory and thus be more reluctant to absorb additional shares all investors may prefer selling their shares into the market today at the average run price, thereby causing the run itself. Consequently, stock prices are low and risk is allocated inefficiently. Liquidity runs and crises are not caused by liquidity shocks per se, but by the fear of future liquidity shocks.

Geometric accuracy of LANDSAT-4 MSS image data

Analyses of the LANDSAT-4 MSS image data of North Georgia provided by the EDC in CCT-p formats reveal that errors of approximately + or - 30 m in the raw data can be reduced to about + or - 55 m based on rectification procedures involving the use of 20 to 30 well-distributed GCPs and 2nd or 3rd degree polynomial equations. Higher order polynomials do not appear to improve the rectification accuracy. A subscene area of 256 x 256 pixels was rectified with a 1st degree polynomial to yield an RMSE sub xy value of + or - 40 m, indicating that USGS 1:24,000 scale quadrangle-sized areas of LANDSAT-4 data can be fitted to a map base with relatively few control points and simple equations. The errors in the rectification process are caused by the spatial resolution of the MSS data, by errors in the maps and GCP digitizing process, and by displacements caused by terrain relief. Overall, due to the improved pointing and attitude control of the spacecraft, the geometric quality of the LANDSAT-4 MSS data appears much improved over that of LANDSATS -1, -2 and -3

The stabilisation of the Nx phase in mixtures

The phase behaviour of mixtures between two symmetric dimers, CBC9CB and the ether-linked analogue CBOC9OCB was investigated by Polarizing Optical Microscopy (POM), Differential Scanning Calorimetry (DSC) and X-Ray Diffraction (XRD) studies. The dimeric constituents are fully miscible and the construction of a temperature-composition phase diagram reveals a surprising amplification of the stability of the Nx phase in compositions of up to 37 wt% of CBOC9OCB in CBC9CB. The origin for this enhancement of stability is discussed and an explanation based on chiral recognition is developed

The Role of Adult Fiddler Crab Environmental Acoustic Cues and Chemical Cues in Stimulating Molting of Field-Caught Megalopae

In mid-Atlantic estuaries, three fiddler crab species, Uca pugilator, Uca pugnax and Uca minax co-occur, with their adults occupying different habitat types distinguished by salinity and sediment size. Some evidence exists that selective settlement is responsible for this separation but the mechanism is largely unknown. We tested the hypothesis that field-caught megalopae would accelerate metamorphosis in the presence of adult species-specific environmental acoustic cues and conspecific chemical cues. We placed megalopae in seawater with and without adult chemical cues, exposed them to one of three sound treatments for 8 days, and recorded the time each megalopa took to metamorphose. In the absence of adult chemical cues, very few megalopae molted regardless of sound treatment. Molting in the presence of habitat sound and chemical cues varied by species. Many U. pugilator molted in all sound and odor combinations, including no odor/sound. U. pugnax was stimulated to molt by chemical cues from either U. pugilator or U. pugnax, but molting was similar across sound treatments. Our results do not support the hypothesis that sound stimulates molting by fiddler crab megalopae, but support the role of chemical odors from adults as molting cues