5,324 research outputs found
Microwave remote sensing of soil moisture, volume 1
Multifrequency sensor data from NASA's C-130 aircraft were used to determine which of the all weather microwave sensors demonstrated the highest correlation to surface soil moisture over optimal bare soil conditions, and to develop and test techniques which use visible/infrared sensors to compensate for the vegetation effect in this sensor's response to soil moisture. The L-band passive microwave radiometer was found to be the most suitable single sensor system to estimate soil moisture over bare fields. The perpendicular vegetation index (PVI) as determined from the visible/infrared sensors was useful as a measure of the vegetation effect on the L-band radiometer response to soil moisture. A linear equation was developed to estimate percent field capacity as a function of L-band emissivity and the vegetation index. The prediction algorithm improves the estimation of moisture significantly over predictions from L-band emissivity alone
Development of visible/infrared/microwave agriculture classification and biomass estimation algorithms, volume 2
Agricultural crop classification models using two or more spectral regions (visible through microwave) were developed and tested and biomass was estimated by including microwave with visible and infrared data. The study was conducted at Guymon, Oklahoma and Dalhart, Texas utilizing aircraft multispectral data and ground truth soil moisture and biomass information. Results indicate that inclusion of C, L, and P band active microwave data from look angles greater than 35 deg from nadir with visible and infrared data improved crop discrimination and biomass estimates compared to results using only visible and infrared data. The active microwave frequencies were sensitive to different biomass levels. In addition, two indices, one using only active microwave data and the other using data from the middle and near infrared bands, were well correlated to total biomass
Multifrequency remote sensing of soil moisture
Multifrequency sensor data collected at Guymon, Oklahoma and Dalhart, Texas using NASA's C-130 aircraft were used to determine which of the all-weather microwave sensors demonstrated the highest correlation to surface soil moisture over optimal bare soil conditions, and to develop and test techniques which use visible/infrared sensors to compensate for the vegetation effect in this sensor's response to soil moisture. The L-band passive microwave radiometer was found to be the most suitable single sensor system to estimate soil moisture over bare fields. In comparison to other active and passive microwave sensors the L-band radiometer (1) was influenced least by ranges in surface roughness; (2) demonstrated the most sensitivity to soil moisture differences in terms of the range of return from the full range of soil moisture; and (3) was less sensitive to errors in measurement in relation to the range of sensor response. L-band emissivity related more strongly to soil moisture when moisture was expressed as percent of field capacity. The perpendicular vegetation index as determined from the visible/infrared sensors was useful as a measure of the vegetation effect on the L-band radiometer response to soil moisture
Development of visible/infrared/microwave agriculture classification and biomass estimation algorithms
Agricultural crop classification models using two or more spectral regions (visible through microwave) are considered in an effort to estimate biomass at Guymon, Oklahoma Dalhart, Texas. Both grounds truth and aerial data were used. Results indicate that inclusion of C, L, and P band active microwave data, from look angles greater than 35 deg from nadir, with visible and infrared data improve crop discrimination and biomass estimates compared to results using only visible and infrared data. The microwave frequencies were sensitive to different biomass levels. The K and C band were sensitive to differences at low biomass levels, while P band was sensitive to differences at high biomass levels. Two indices, one using only active microwave data and the other using data from the middle and near infrared bands, were well correlated to total biomass. It is implied that inclusion of active microwave sensors with visible and infrared sensors on future satellites could aid in crop discrimination and biomass estimation
Measurement of soil moisture trends with airborne scatterometers
In an effort to investigate aircraft multisensor responses to soil moisture and vegetation in agricultural fields, an intensive ground sampling program was conducted in Guymon, Oklahoma and Dalhart, Texas in conjunction with aircraft data collected for visible/infrared and passive and active microwave systems. Field selections, sampling techniques, data processing, and the aircraft schedule are discussed for both sites. Field notes are included along with final (normalized and corrected) data sets
Mutations of the mitochondrial ND1 gene as a cause of MELAS
Copyright © 2004 by the BMJ Publishing Group Ltd. All rights reserved. BMJ JournalsD. M. Kirby, R. McFarland, A. Ohtake, C. Dunning, M. T. Ryan, C. Wilson, D. Ketteridge, D. M. Turnbull, D. R. Thorburn, R. W. Taylo
Arkansas\u27 Incendiary Wildfire Record: 1983-1987
All wildfire reports from lands protected by the Arkansas Forestry Commission for the calendar years 1983 through 1987 were studied. The number of wildfires steadily increased from 2,185 in 1983 to 4,150 in 1987, burning a total of 27,146 hectares in 1987. Incendiarism on forested lands in 1987 comprised 77% of the total fires and 84% of the area burned. Incendiarism was responsible for 40% of all fires and 60% of the area burned in 1983, but increased to 54% of all fires and 69% of the area burned in 1987. In 1987, 80% of all incendiary fires on industry lands were started by local residents. Most incendiary fires occurred on Class 3 (52%) and Class-2 (27%) fire-danger class-days. More incendiary fires (64%) occurred during the spring fire season (January through June). The general public reported 66% the non-incendiary fires, but only 56% of the incendiary-caused fires. Implications of these findings for wildfire prevention programs are discussed
Proteins to Order Use of Synthetic DNA to Generate Site-Specific Mutations
The ability to cause specific changes in the amino acid
sequences of proteins would greatly advance studies on the
influence of protein structure on biochemical function. If
the desired changes can once be made in the nucleic acid
which encodes the protein, one can use cloning in an appropriate microorganism to produce essentially limitless
quantities of the mutant protein. We describe here the
application of oligonucleotide-directed site-specific mutagenesis to accomplish this objective for the enzyme
B-lactamase, the gene for which is contained in the plasmid
pBR322. The method uses a procedure to screen for mutant clones which depends on the DNA in the various colonies and not on the properties of the mutant protein; the method can, therefore, be widely applied and does not require, in each separate case, the development of a screening procedure which depends on some phenotypic difference between mutant and wild-type protein
Quantum beat spectroscopy: stimulated emission probe of hyperfine quantum beats in the atomic Cs 8p level
Measurements of hyperfine polarization quantum beats are used determine the
magnetic dipole (A) and electric quadrupole (B) coupling constants in the
excited atomic Cs 8p level. The experimental approach is a novel combination of
pulsed optical pumping and time-delayed stimulated emission probing of the
excited level. From the measured evolution of the atomic linear polarization
degree as a function of probe delay time, we determine the hyperfine coupling
constants A = 7.42(6) MHz and B = 0.14(29) MHz
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