Stray light correction algorithm for multichannel hyperspectral spectrographs.

An algorithm is presented that corrects a multichannel fiber-coupled spectrograph for stray or scattered light within the system. The efficacy of the algorithm is evaluated based on a series of validation measurements of sources with different spectral distributions. This is the first application of a scattered-light correction algorithm to a multichannel hyperspectral spectrograph. The algorithm, based on characterization measurements using a tunable laser system, can be extended to correct for finite point-spread response in imaging systems.

Calibration of SeaWiFS. II. Vicarious techniques.

We present an overview of the vicarious calibration of the Sea-Viewing Wide Field-of-view Sensor (SeaWiFS). This program has three components: the calibration of the near-infrared bands so that the atmospheric correction algorithm retrieves the optical properties of maritime aerosols in the open ocean; the calibration of the visible bands against in-water measurements from the Marine Optical Buoy (MOBY); and a calibration-verification program that uses comparisons between SeaWiFS retrievals and globally distributed in situ measurements of water-leaving radiances. This paper describes the procedures as implemented for the third reprocessing of the SeaWiFS global mission data set. The uncertainty in the near-infrared vicarious gain is 0.9%. The uncertainties in the visible-band vicarious gains are 0.3%, corresponding to uncertainties in the water-leaving radiances of approximately 3%. The means of the SeaWiFS/in situ matchup ratios for water-leaving radiances are typically within 5% of unity in Case 1 waters, while chlorophyll a ratios are within 1% of unity. SeaWiFS is the first ocean-color mission to use an extensive and ongoing prelaunch and postlaunch calibration program, and the matchup results demonstrate the benefits of a comprehensive approach.

The city government's role in community health improvement.

Amid increasing pressures to address complex issues not traditionally assigned to localities, Healthy Cities is seen as a powerful model for community improvement and quality-of-life enhancements for individuals and organizations willing to think beyond the traditional local government management models and responsibilities. As a model for community-oriented government, it offers opportunities for fostering a return to "barnraising" concepts, civic responsibility, participation, tailoring solutions to local circumstances, and the transition of local government to governance models.

Performance evaluation of a permeable reactive barrier for remediation of dissolved chlorinated solvents in groundwater.

A pilot-scale permeable reactive barrier (PRB) consisting of granular iron was installed in May 1995 at an industrial facility in New York to evaluate the use of this technology for remediation of chlorinated volatile organic compounds (VOCs) in groundwater. The performance of the barrier was monitored over a 2-year period. Groundwater velocity through the barrier was determined using water level measurements, tracer tests, and in situ velocity measurements. While uncertainty in the measured groundwater velocity hampered interpretation of results, the VOC concentration data from wells in the PRB indicated that VOC degradation rates were similar to those anticipated from laboratory results. Groundwater and core analyses indicated that formation of carbonate precipitates occurred in the upgradient section of the iron zone, however, these precipitates did not appear to adversely affect system performance. There was no indication of microbial fouling of the system over the monitoring period. Based on the observed performance of the pilot, a full-scale iron PRB was installed at the site in December 1997.

Invasion of respiratory epithelial cells by Burkholderia (Pseudomonas) cepacia.

Pulmonary infections caused by Burkholderia (Pseudomonas) cepacia are an important cause of morbidity and mortality in cystic fibrosis (CF) patients. Several features suggestive of cellular invasion and intracellular sequestration of B. cepacia in CF are persistence of infection in the face of antibiotic therapy to which the organism demonstrates in vitro susceptibility and a propensity to cause bacteremic infections in patients with CF. Epithelial cell invasion was demonstrated in vitro in A549 cells by a modified gentamicin protection assay. The kinetics of invasion appear to be saturable. Electron microscopy of invaded monolayers showed intracytoplasmic bacteria enclosed by membrane-bound vacuoles. No lysosomal fusion with these vacuoles was observed. Intraepithelial cell replication was suggested by electron microscopy and confirmed by both a quantitative assay and a visual assay. Cytochalasin D, but not colchicine, inhibited invasion, suggesting a role for microfilaments but not microtubules. The invasion phenotype in B. cepacia may be an important virulence factor for CF infections.

Salicylate-inducible antibiotic resistance in Pseudomonas cepacia associated with absence of a pore-forming outer membrane protein.

The most common mechanism of antibiotic resistance in multiply resistant Pseudomonas cepacia is decreased porin-mediated outer membrane permeability. In some gram-negative organisms this form of antibiotic resistance can be induced by growth in the presence of weak acids, such as salicylates, which suppress porin synthesis. To determine the effects of salicylates on outer membrane permeability of P. cepacia, a susceptible laboratory strain, 249-2, was grown in 10 mM sodium salicylate. Antibiotic susceptibility and uptake, as well as outer membrane protein patterns, were compared between strain 249-2 grown with and without salicylates. The MICs of chloramphenicol, trimethoprim, ciprofloxacin, and ceftazidime were compared between organisms grown in standard and salicylate-containing medium and are as follows: chloramphenicol, 12.5 versus 100 micrograms/ml; trimethoprim, 0.78 versus 3.125 micrograms/ml; ciprofloxacin, 0.4 versus 1.56 micrograms/ml; ceftazidime, 3.125 versus 3.125 micrograms/ml. The permeability of beta-lactam antibiotics was calculated from the rate of hydrolysis of the chromogenic cephalosporin, PADAC. There was no significant difference between strains grown in the presence and absence of salicylate. By using high-pressure liquid chromatography quantitation of loss from culture medium, the effect of 10 mM salicylate on the cellular permeability of chloramphenicol was measured in strain 249-2 by introduction of a plasmid which encodes production of chloramphenicol acetyltransferase. After 1 h of incubation, 18.5% +/- 1.54% versus 70.1% +/- 3.52%, and after 2 h, 4.20% +/- 1.65% versus 41.90% +/- 2.16% remained in supernatants from organisms grown in the absence and presence of 10 mM salicylate, respectively. Outer membrane protein pattern analysis demonstrated the absence of a protein of apparent molecular weight of 40,000 when strain 249-2 was grown in the presence of 10 mM salicylate. To determine whether this protein functioned as a porin, reconstituted membrane vesicles were constructed to assess antibiotic permeability. Vesicles constructed with this salicylate-suppressible outer membrane protein (OpcS) were permeable to chloramphenicol but not to penicillin G. These findings suggest that OpcS is a selective, antibiotic-permeable porin which can be suppressed by growth in the presence of salicylate. Further investigation will be required to determine the biochemical effects of salicylate on porin synthesis.

Identification of negative strand and positive strand RNA of canine distemper virus in animal tissues using single stranded RNA probes.

In this report, we describe a technique for identifying negative strand (genome) and positive strand (messenger) RNA of canine distemper virus (CDV) in dog tissues by using single stranded RNA probes. Plasmids (pSP64-P and pSP65-P) which contain insert DNA corresponding to the P gene of CDV were transcribed by SP6 polymerase in the presence of radioisotope to produce radiolabeled single stranded RNA probes. RNA transcribed from pSP65-P is complementary to the negative strand (genome) and RNA produced from pSP64-P is complementary to the positive strand (message) of CDV. The binding specificity of the single stranded RNA probes was determined on Northern-blots. The use of these RNA probes in hybridization assays resulted in greater sensitivity and specificity than that obtained from double stranded DNA probes (either whole plasmids or purified insert DNA) which were labeled by the nick translation reaction. We also describe the making of single stranded DNA probes by reverse transcription labeling of complementary RNA. The complementary RNA was produced by the transcription of cloned DNA (pSP64-P and pSP65P). Single stranded RNA probes and single stranded DNA probes were similar in sensitivity. The single stranded RNA and DNA probes were applied to ethanolacetic acid fixed tissue sections from dogs infected with CDV-A75/17. We used 32P-labeled probes in tissue hybridizations and 35S-labeled probes in in situ hybridizations to identify negative and positive stranded CDV RNA. In this report we demonstrate that single stranded RNA and DNA probes can be used successfully in tissue hybridization and in situ hybridization assays to study viral expression in this virus-host system.

Phytoplankton pigment concentrations in the Middle Atlantic Bight: comparison of ship determinations and CZCS estimates.

The processing algorithms used for relating the apparent color of the ocean observed with the Coastal-Zone Color Scanner on Nimbus-7 to the concentration of phytoplankton pigments (principally the pigment responsible for photosynthesis, chlorophyll a) are developed and discussed in detail. These algorithms are applied to the shelf and slope waters of the Middle Atlantic Bight and also to Sargasso Sea waters. In all, four images are examined, and the resulting pigment concentrations are compared to continuous measurements made along ship tracks. The results suggest that over the 0.08-1.5-mg/m3 range the error in the retrieved pigment concentration is of the order of 30-40% for a variety of atmospheric turbidities. In three direct comparisons between ship-measured and satellite-retrieved values of the water-leaving radiance the atmospheric correction algorithm retrieved the water-leaving radiance with an average error of approximately 10%. This atmospheric correction algorithm does not require any surface measurements for its application.

Clear water radiances for atmospheric correction of coastal zone color scanner imagery.

The possibility that the inherent sea surface spectral radiance of clear water can be computed in the green, yellow, and red regions of the spectrum solely from a knowledge of the solar zenith angle is developed in detail. This concept is tested with experimental data, and the results indicate that the normalized inherent sea surface spectral radiance is constant to within ~10% for Morel's Case 1 waters as long as the phytoplankton pigment concentration does not exceed 0.25 mg/m(3). In the same conditions the radiance at 670 nm is <0.012 mW/cm(2) microm sr. A scheme to implement this clear water radiance concept for atmospheric correction of CZCS imagery is presented.

Nimbus-7 coastal zone color scanner: system description and initial imagery.

The Coastal Zone Color Scanner (CZCS) on Nimbus-7, launched in October 1978, is the only sensor in orbit that is specifically designed to study living marine resources. The initial imagery confirms that CZCS data can be processed to a level that reveals subtle variations in the concentration of phytoplankton pigments. This development has potential applications for the study of large-scale patchiness in phytoplankton distributions, the evolution of spring blooms, water mass boundaries, and mesoscale circulation patterns.

Phytoplankton pigments from the nimbus-7 coastal zone color scanner: comparisons with surface measurements.

The removal of atmospheric effects from Nimbus-7 Coastal Zone Color Scanner (CZCS) images reveals eddy-like ocean turbidity patterns not apparent in the original calibrated images. Comparisons of the phytoplankton pigment concentrations derived from the corrected CZCS radiances with surface measurements agree to within less than 0.5 log C, where C is the sum of the concentrations of chlorophyll a plus phaeopigments a (in milligrams per cubic meter).

Effects of changes in arterial carbon dioxide tension on oxygen consumption during cardiopulmonary bypass.

The effects of changes in arterial carbon dioxide tension (PaCO2) on the oxygenation of tissues in 34 patients undergoing surgery for aortocoronary bypass were studied while temperature, systemic blood flow, and the delivery of oxygen to the peripheral tissues remained constant. Mixed venous and superior vena caval oxygen tensions (PvO2 and PsvcO2, respectively) and oxyhemoglobin saturations and the in vivo partial pressure of oxygen at which 50 percent of the hemoglobin is saturated (P50) increased with PaCO2, while peripheral vascular resistance, in vitro P50, the level of 2,3-diphosphoglyceric acid in the red blood cells, and the level of lactate in the blood remained constant. There was a close correlation between increases in PaCO2 and increases in PvO2 (r = 0.912; P less than 0.001) but not increases in PsvcO2 (r = 0.364; not significant). This indicated that the total-body consumption of oxygen diminished with increases in PaCO2 but that some regional redistribution of oxygen consumption occurred between the superior and inferior vena caval vascular beds. Since the level of lactate in the blood remained constant and since signs of metabolism acidosis did not develop, the reduced oxygen consumption due to increases in PaCO2 did not result in detectable increases in anaerobic metabolism.

Effects of ischemia on the oxygen diffusion coefficients in the brain cortex (studies on Macaca irus).

In this series of experiments changes in oxygen diffusion coefficients were measured in waking primates undergoing focal middle cerebral artery ischemia; Ligation of the middle cerebral artery followed by a decrease of the oxygen diffusion coefficient in the areas supplied by that vessel to levels ten to twenty per cent below normal by twenty-five minutes following onset of ischemia. Following release and re-perfusion diffusion coefficient gradually increases and reaches a super normal peak value three hours after release of ligation. This is followed by a gradual reduction in diffusion coefficient with stabilization at preocclusion levels. In the three experiments described these changes following re-perfusion corresponded with clinical improvement of the neurological status of the monkeys;