The Use of Principal Components for Creating Improved Imagery for Geometric Control Point Selection

A directed principal component (PC) analysis and its transformation was applied to 7-channel thematic mapper simulator (TMS) data and 4-channel LANDSAT multispectral scanner system (MSS) data collected over the city of Lancaster, Pennsylvania, to create improved imagery for geometric control point selection for image to image registration. Nineteen temporally stable geometric control points, such as road interactions and bridges, were selected for a 236 sq km area. The control points were visible on both the TMS and MSS imagery. On the first attempt the corresponding image control points were selected on both data sets without using the principal components transformation. Many of the road intersection locations were visible but the actual road crossings could not be distinguished. As a result, mensuration errors using raw data exceeded the equivalent of two (79 x 79 m) pixels. The application of a guided principal components transformation yielded TMS and MSS single band images showing improved detail in the scene's urban and residential infrastructure. The PC transformed data sets were then utilized for the reselection of geometric control points. By shown greater detail, control points on both the TMS and MSS imagery could be located with greater precision using the PC transformed data

The ultraviolet variability of the T Tauri star RW Aurigae

Between 1978 and 1979 the visible brightness of RW Aurigae increased by 0.9 mag. During this time (1) CIV and SiIV increased by factors of 2 to 4 while the lower ionization lines remained unchanged; (2) the fluorescent OI line increased by a factor of 8; (3) the shell spectrum changed from emission to absorption; and (4) the ultraviolet continuum brightened by 2.3 mag. On a time scale of a week the continuum varied by as much as 0.8 mag., but the MgII emission lines showed no variability over 10 percent. An active chromosphere, transition region, and envelope cooled by mass loss are hypothesized in order to explain the ultraviolet observations of RW Aur

Principal Components as a Data Reduction and Noise Reduction Technique

The potential of principal components as a pipeline data reduction technique for thematic mapper data was assessed and principal components analysis and its transformation as a noise reduction technique was examined. Two primary factors were considered: (1) how might data reduction and noise reduction using the principal components transformation affect the extraction of accurate spectral classifications; and (2) what are the real savings in terms of computer processing and storage costs of using reduced data over the full 7-band TM complement. An area in central Pennsylvania was chosen for a study area. The image data for the project were collected using the Earth Resources Laboratory's thematic mapper simulator (TMS) instrument

A new look at the Bezold–Brücke hue shift in the peripheral retina

AbstractExperiments were conducted with a bipartite field to better understand the Bezold–Brücke hue shift in the peripheral retina. The first experiment measured hue shift in the fovea and at 1° and 8° along the horizontal meridian of the nasal retina for nominal test wavelengths of 430, 450, 490, 520 and 610 nm. Peripheral measurements were obtained under two adaptation conditions: after 30 min dark adaptation and following a rod-bleach. Results indicated that foveal hue shifts differed from those obtained after a rod-bleach. Data from the rod-bleach and no-bleach conditions in the periphery were similar, indicating that rods could not account for the differences between the foveal data and the rod-bleach peripheral data. Hue shifts obtained for the 520 nm test stimulus, and to a smaller extent other test wavelengths, at 8° nasal retinal eccentricity revealed that the wavelength of the matching stimulus depended upon the lateral position of the matching and test fields, and this effect was greater in the no-bleach condition than the rod-bleach condition. Several factors were investigated in experiments 2 and 3 to explain the results with the 520 nm test field. It appears that differential rod density under the two half fields and the compression of photoreceptors by the optic disk may partially, but not fully, account for the 520 nm effect

Delineation of Soil Boundaries Using Image Enhancement and Spectral Signature Classification of Landsat Data

The concept of using satellite data for soils inventories began with the advent of the first ERTS launch in 1972. Landsat data can be useful in a field survey, if it satisfies one or both of two requirements: the products must improve the accuracy of the survey and/or it must expedite the survey. These goals can be achieved by creating products that enhance and delineate soil surface features that would not necessarily identify specific soil types but rather provide a spatial boundary that a field scientist could observe and evaluate. A 250,000 acre tract of semiarid rangeland in east central Utah was selected as the study area. A June 13, 1977 Landsat scene was chosen for analysis. The color composite combined with such ancillary data as geologic maps and topographic quadrangles aided in partitioning the study site in to areas of physiographic homogeneity. A principle components transformation was performed on the data and a uniform contrast stretch was applied to the unaltered spectral bands and the transformed axes. The contrast stretch increased the dynamic tonal range of the data, and created as many as 32 different tonal classes. Various color combinations and a number of density slices were evaluated for their interpretability. A spectral signature classification of the June scene was developed using both supervised and unsupervised classification algorithms. A canonical analysis was then performed on the thematic maps to improve class separability for image enhancement. The more promising image products were geometrically corrected, scaled to 1:24,000, and merged with data digitized from a partially completed soils map. The resulting map allowed comparisons between soil lines drawn by a field soil mapper and the classes defined by computer analysis. Both the enhanced images and the spectral classification maps aided in the delineation of soil boundaries. Enhanced images are inexpensive to generate and, as no subjective class groupings are made, have the added quality of objectivity. The spectral classification maps defined surface characteristics that could be used to help separate soil units. A cost analysis for the individual products and an indepth field evaluation is being completed

Second Eastern Regional Remote Sensing Applications Conference

Participants from state and local governments share experiences in remote sensing applications with one another and with users in the Federal government, universities, and the private sector during technical sessions and forums covering agriculture and forestry; land cover analysis and planning; surface mining and energy; data processing; water quality and the coastal zone; geographic information systems; and user development programs

Enhancement of optical absorption in multiferroic (1-x)PZT-xPFN thin films: Experiments and first-principles analysis

Multiferroic compounds have gained research attention in the field of ferroelectric photovoltaics due to the presence of transition-metal d states from magnetic ions, which tend to reduce the bandgap value. In this work, 0.5Pb(Zr0.52Ti0.48)O3 - 0.5Pb(Fe0.5Nb0.5)O3 PZTFN0.5 thin films were synthesized using a sol-gel route to investigate the effect of iron doping on optical and multiferroic properties. For comparative analysis, the end-member compositions, Pb(Zr0.52Ti0.48)O3 (PZT) and Pb(Fe0.5Nb0.5)O3 (PFN), were also synthesized under identical conditions. Our results revealed that the presence of Fe ions, besides inducing multiferroic behavior, effectively enhances the optical absorption of the material in the visible light region. Optical transitions at 3.0 eV (2.4 eV) and 2.7 eV (2.2 eV) for the direct (indirect) bandgap were determined for PZTFN0.5 and PFN, respectively, indicating that the absorption edges of the iron-containing films result more promising than PZT (Eg 3.6eV) for photovoltaic applications. Both PZTFN0.5 and PFN thin films exhibit multiferroic behavior at room temperature, with different electric and magnetic properties. While PZTFN0.5 presents saturated hysteresis loops with remanent polarization values around 10 uC/cm2 and magnetization of 1.6 emu/cm2, PFN displays significantly larger remanence (31 emu/cm2) but poorer ferroelectric properties due to the presence of leakage. Microscopic insights into the structural and electronic properties of the PZTFN0.5 solid solution were provided from first-principles calculations

Ultraviolet and Multiwavelength Variability of the Blazar 3C 279: Evidence for Thermal Emission

The gamma-ray blazar 3C 279 was monitored on a nearly daily basis with IUE, ROSAT and EGRET for three weeks between December 1992 and January 1993. During this period, the blazar was at a historical minimum at all wavelengths. Here we present the UV data obtained during the above multiwavelength campaign. A maximum UV variation of ~50% is detected, while during the same period the X-ray flux varied by no more than 13%. At the lowest UV flux level the average spectrum in the 1230-2700 A interval is unusually flat for this object (~1). The flattening could represent the lowest energy tail of the inverse Compton component responsible for the X-ray emission, or could be due to the presence of a thermal component at ~20000 K possibly associated with an accretion disk. The presence of an accretion disk in this blazar object, likely observable only in very low states and otherwise hidden by the beamed, variable synchrotron component, would be consistent with the scenario in which the seed photons for the inverse Compton mechanism producing the gamma-rays are external to the relativistic jet. We further discuss the long term correlation of the UV flux with the X-ray and gamma-ray fluxes obtained at various epochs. All UV archival data are included in the analysis. Both the X- and gamma-ray fluxes are generally well correlated with the UV flux, approximately with square root and quadratic dependences, respectively.Comment: 22 pages, Latex, 7 PostScript figures, to appear in The Astrophysical Journa

Sol-gel synthesis and multiferroic properties of pyrochlore-free Pb(Fe0.5Nb0.5)O3 thin films

Lead iron niobate (PbFe0.5Nb0.5O3 - PFN) thin films were synthesized by a modified sol-gel route, which offers the advantage of a rapid, simple and non-toxic reaction method. Polycrystalline perovskite-structured PFN thin films without pyrochlore phases were obtained on Pt/Ti/SiO2/Si substrates after sintering by rapid thermal annealing at 650 {\deg}C. TEM and AFM images confirmed the excellent quality of the sintered film, while EDS spectroscopy revealed the presence of oxygen vacancies near the film/substrate interface. Electric measurements show good dielectric properties and ferroelectric behavior, characterized by typical C-V curves and well-defined P-E ferroelectric loops at 1 kHz, with remanent polarization values of ~12 uC/cm2. The polarization, however, increases with decreasing frequency, indicating the presence of leakage currents. I-V measurements show a significant increase in DC-conduction at relatively low fields (around 100 kV/cm). The films display ferromagnetic behavior at room temperature, with magnetic remanence around 30 emu/cm3 and a coercive field of 1 kOe. These values are significantly higher than those obtained for PFN powders fabricated by the same sol-gel route, as well as the magnetization values reported in the literature for epitaxial films.Comment: 24 pages, 10 figure

Thiorhodospira sibirica gen. nov., and sp. nov., a new alkaliphilic purple sulfur bacterium from a Siberian soda lake

A new purple sulfur bacterium was isolated from microbial films on decaying plant mass in the near-shore area of the soda lake Malyi Kasytui (pH 9.5, 0.2% salinity) located in the steppe of the Chita region of south-east Siberia. Single cells were vibrioid- or spiral-shaped (3-4 microns wide and 7-20 microns long) and motile by means of a polar tuft of flagella. Internal photosynthetic membranes were of the lamellar type. Lamellae almost filled the whole cell, forming strands and coils. Photosynthetic pigments were bacteriochlorophyll a and carotenoids of the spirilloxanthin group. The new bacterium was strictly anaerobic. Under anoxic conditions, hydrogen sulfide and elemental sulfur were used as photosynthetic electron donors. During growth on sulfide, sulfur globules were formed as intermediate oxidation products. They were deposited outside the cytoplasm of the cells, in the peripheral periplasmic space and extracellularly. Thiosulfate was not used. Carbon dioxide, acetate, pyruvate, propionate, succinate, fumarate and malate were utilized as carbon sources. Optimum growth rates were obtained at pH 9.0 and optimum temperature was 30 degrees C. Good growth was observed in a mineral salts medium containing 5 g sodium bicarbonate l-1 without sodium chloride. The new bacterium tolerated up to 60 g sodium chloride l-1 and up to 80 g sodium carbonates l-1. Growth factors were not required. The DNA G + C composition was 56.0-57.4 mol%. Based on physiological, biochemical and genetic characteristics, the newly isolated bacterium is recognized as a new species of a new genus with the proposed name Thiorhodospira sibirica