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PubMed1980

Role of microorganisms in the consumption and production of atmospheric carbon monoxide by soil.

Consumption and production of atmospheric CO was measured under field conditions in three different types of soil. CO was consumed by an apparent first-order reaction and produced by an apparent zero-order reaction, resulting in a dynamic equilibrium with the consumption of atmospheric CO as the net reaction. CO consumption was higher in summer than in winter. Laboratory experiments on five different soil types showed that CO consumption was strongly inhibited by the presence of streptomycin or cycloheximide (Actidione), or both. Thus, eucaryotic as well as procaryotic microorganisms were apparently responsible for the observed CO consumption. The aerobic carboxydobacterium Pseudomonas carboxydovorans added to sterile soil was able to utilize the low amounts (ca. 0.7 ppmv) of CO present in laboratory air. CO was consumed by soil under aerobic as well as anaerobic conditions. Anaerobic preincubation of the soil stimulated the anaerobic CO consumption and reduced the aerobic CO consumption. In contrast to CO consumption, CO production was stimulated by autoclaving, by ultraviolet-irradiation, by fumigation with NH(3) or CHCl(3), by treatment with streptomycin or cycloheximide or both, by addition of NaCN, NaN(3), or Na(2)HAsO(4) (or all three) in the presence of glucose under an atmosphere of pure oxygen, or by a drying and rewetting procedure. The consumption of atmospheric CO by soil is a microbial process, but the production of CO is apparently not a metabolic process.

Journal Article↗
PubMed1994

Mechanistic analysis of ammonium inhibition of atmospheric methane consumption in forest soils.

Methane consumption by forest soil was studied in situ and in vitro with respect to responses to nitrogen additions at atmospheric and elevated methane concentrations. Methane concentrations in intact soil decreased continuously from atmospheric levels at the surface to 0.5 ppm at a depth of 14 cm. The consumption rate of atmospheric methane in soils, however, was highest in the 4- to 8-cm depth interval (2.9 nmol per g of dry soil per day), with much lower activities below and above this zone. In contrast, extractable ammonium and nitrate concentrations were highest in the surface layer (0 to 2 cm; 22 and 1.6 mumol per g of dry soil, respectively), as was potential ammonium-oxidizing activity (19 nmol per g of dry soil per day). The difference in zonation between ammonium oxidation and methane consumption suggested that ammonia-oxidizing bacteria did not contribute significantly to atmospheric methane consumption. Exogenous ammonium inhibited methane consumption in situ and in vitro, but the pattern of inhibition did not conform to expectations based on simple competition between ammonia and methane for methane monooxygenase. The extent of ammonium inhibition increased with increasing methane concentration. Inhibition by a single ammonium addition remained constant over a period of 39 days. In addition, nitrite, the end product of methanotrophic ammonia oxidation, was a more effective inhibitor of methane consumption than ammonium. Factors that stimulated ammonium oxidation in soil, e.g., elevated methane concentrations and the availability of cosubstrates such as formate, methanol, or beta-hydroxybutyrate, enhanced ammonium inhibition of methane oxidation, probably as a result of enhanced nitrite production.

Journal Article↗
PubMed1998

Methanol promotes atmospheric methane oxidation by methanotrophic cultures and soils.

Two methanotrophic bacteria, Methylobacter albus BG8 and Methylosinus trichosporium OB3b, oxidized atmospheric methane during batch growth on methanol. Methane consumption was rapidly and substantially diminished (95% over 9 days) when washed cell suspensions were incubated without methanol in the presence of atmospheric methane (1.7 ppm). Methanotrophic activity was stimulated after methanol (10 mM) but not methane (1,000 ppm) addition. M. albus BG8 grown in continuous culture for 80 days with methanol retained the ability to oxidize atmospheric methane and oxidized methane in a chemostat air supply. Methane oxidation during growth on methanol was not affected by methane deprivation. Differences in the kinetics of methane uptake (apparent K(m) and V(max)) were observed between batch- and chemostat-grown cultures. The V(max) and apparent K(m) values (means +/- standard errors) for methanol-limited chemostat cultures were 133 +/- 46 nmol of methane 10 cells h and 916 +/- 235 ppm of methane (1.2 muM), respectively. These values were significantly lower than those determined with batch-grown cultures (V(max) of 648 +/- 195 nmol of methane 10 cells h and apparent K(m) of 5,025 +/- 1,234 ppm of methane [6.3 muM]). Methane consumption by soils was stimulated by the addition of methanol. These results suggest that methanol or other nonmethane substrates may promote atmospheric methane oxidation in situ.

Journal Article↗
PubMed1966

Microorganisms of the upper atmosphere. V. Relationship between frontal activity and the micropopulation at altitude.

The relationship between frontal activity and the micropopulation of the atmosphere at altitude is described. It is shown that certain of the meteorological events associated with frontal activity quantitatively modify the micropopulation of the atmosphere. Precipitation associated with frontal passage reduces the micropopulation at altitude, whereas frontal activity with high levels of associated surface and atmospheric turbulence results in great increases in micropopulations of the upper atmosphere-particularly in those situations where surface conditions are conductive to the development of dust.

Air Microbiology↗
PubMed1974

Influence of incubation atmosphere on growth and amino acid requirements of Streptococcus mutans.

The growth response of Streptococcus mutans representing antigenic type a or d in a chemically defined medium was influenced by the oxygen concentration of the growth atmosphere. Under controlled aerobic (1.5% O(2)) conditions these cultures attained a greater density than when the atmosphere contained 0.006% O(2) or less. The growth of S. mutans strains representing antigenic types b or c in the defined medium was independent of the oxygen concentration of the growth environment. Under the conditions used in this study, none of the strains tested could utilize ammonium ion as a sole source of nitrogen for growth. The requirement for certain amino acids and inhibition by other amino acids varied with antigenic type and relative oxygen concentration of the growth environment. Under conditions where the atmospheric oxygen was reduced to 0.0006% O(2) or less, the amino acid requirements of the cultures became either more numerous or more stringent. S. mutans strains of type c generally required the least number of amino acids, whereas cultures of type d had more numerous requirements. Nearly every culture tested under the anaerobic atmosphere was inhibited by one of the branched-chain amino acids, leucine, valine, or isoleucine. Methionine and lysine were also found to be inhibitory, particularly toward the type c strains.

Amino Acids↗
PubMed1975

Influence of modified atmosphere storage on aflatoxin production in high moisture corn.

Samples of freshly harvested corn and remoistened corn were inoculated with Asphergillus flavus and stored for 4 weeks at about 27 C in air and three modified atmospheres. Aflatoxins and fat acidity were determined weekly. Corn stored in the modified atmospheres did not accumulate over 15 mug of total aflatoxins per kg. Corn from the high CO2 treatment (61.7 per cent CO2, 8.7 per cent O2, and 29.6 per cent N2) was visibly molded at 4 weeks and had a higher fat acidity than the other treatments. In the N2 (99.7 per cent N2 and 0.3 per cent O2) and controlled atmosphere (13.5 per cent CO2, 0.5 per cent O2, 84.5 per cent N2) treatments, a fermentation-like odor was detected. When the corn was removed from the modified atmospheres it deteriorated rapidly and was soon contaminated with aflatoxins.

Aflatoxins↗
PubMed1982

Comparison of atmospheres of incubation for primary isolation of Campylobacter fetus subsp. jejuni from animal specimens: 5% oxygen versus candle jar.

An atmosphere with reduced oxygen tension is required for the primary isolation of Campylobacter fetus subsp. jejuni. Therefore, we compared use of the conventional atmosphere of 5% oxygen and 8% carbon dioxide with use of a candle jar (17% oxygen and 3% carbon dioxide) for primary isolation of C. fetus subsp. jejuni from 263 positive canine, cattle, and turkey fecal or cecal specimens. At an incubation temperature of 42 degrees C, the atmosphere with 5% oxygen resulted in more Campylobacter colonies per plate (P less than 0.005) and consistently larger Campylobacter colonies (P less than 0.005) than did the candle jar, whereas the growth of interfering flora was similar. Overall, 96% of the 263 specimens were positive for C. fetus subsp. jejuni with 5% oxygen, and 90% were positive with the candle jar (P less than 0.02). More striking differences in isolation rates were seen when both the temperature and the atmosphere were varied: 5% oxygen at 42 degrees C enabled recovery of 93% of the isolates from 70 positive specimens, versus 46% recovery with the candle jar at 37 degrees C. Results with 5% oxygen at 37 degrees C were intermediate. The addition of FBP supplement (0.25% each of ferrous sulfate, sodium metabisulfite, and sodium pyruvate) to Campy-BAP selective medium made no improvement over unsupplemented medium at 42 degrees C (whether in 5% oxygen or in the candle jar), but there was significant improvement over unsupplemented medium when both media were incubated at 37 degrees in the candle jar.

Animals↗
PubMed2004

Influence of ambient atmosphere on charge transport in polycrystalline thin films of three simple aromatic hydrocarbons.

Drift mobility of charge carriers in p-terphenyl, p-quaterphenyl and tetracene polycrystalline thin films was measured using the classical time-of-flight method. The measurements were carried out both in the atmosphere and in vacuum of the order of 10( - 3) Torr. The mobility measured in the atmosphere is of the order of 10(-4)cm2 V(-1) s(-1) and turns out to be about 1 order of magnitude higher than that measured in vacuum. It is suggested that the hopping transport of charge dominates in the structures investigated. The increase in the mobility for the measurements in the atmosphere probably results from the additional localized states due to water and other atmosphere molecules.

Journal Article↗
PubMed2004

Helping alliance and ward atmosphere in psychiatric in-patient care.

OBJECTIVE: The study investigated how patients in a psychiatric in-patient ward perceived the therapeutic relationship and the ward atmosphere, the interrelationships between these phenomena, and whether demographic and clinical factors had an influence on the helping alliance. DESIGN: This was an explorative study in a natural setting. A correlational and multiple regression design were adopted. METHOD: All discharged patients (N = 61) during a limited period completed questionnaires regarding the ward atmosphere and the helping alliance, were rated on psychosocial functioning, and diagnosed according to the ICD-10. RESULTS: Several ward-atmosphere factors correlated with the helping alliance. A multivariate analysis suggested that support, programme clarity, and spontaneity were important ingredients and that support was the most important contributor. Patients with a high level of psychosocial functioning established a better helping alliance and patients with personality disorders tended to develop a weaker helping alliance. CONCLUSION: The findings emphasize that a holding environment is important in establishing a good helping alliance, which is consistent with results from the psychotherapy area. Since helping alliance is known to have a most important influence on therapy outcome, one conclusion must be that the staff, in their endeavour to strengthen the supportive element of the ward atmosphere, may improve the therapeutic outcome as well.

Adult↗
PubMed2002

Ground-based satellite-type images of the upper-atmosphere emissive layer.

With the introduction of infrared (IR) retina sensors used as focal-plane arrays in large telescopes, astronomical observations are now frequently located in the near-IR part of the spectrum. In this region the upper atmosphere introduces in the 0.7-3 microns range an additional component due to the OH vibrational band emission that should be subtracted from the astronomical data. Observations of this upper-atmosphere emission performed at the Pic de Châteaurenard (altitude of 2989 m) are presented here. A panoramic image of the emission is constructed by use of a set of 48 images obtained with a CCD camera mounted on an alt-azimuthal platform. After a numerical filter is used to suppress the star images, the atmospheric emission shows two distinct sets of arches vanishing at two opposite points in the WNW and ESE azimuths. The emissive layer, caused by the ozone-hydrogen reaction, is thin and located at the altitude of 85 km. By use of these data, the perspective effect that produces the panoramic arches is inverted in introducing the concept of a virtual camera. The Van Rhijn effect and the refraction correction are taken into account. The three punctual transformations that use matrix algorithms are analyzed. The result is a satellite-type view of the emissive layer that appears as a disk having a radius of approximately 1100 km. This disk is limited by the summit line of the Alps surrounding the Pic de Châteaurenard. The field of view covers a large part of Europe, the Mediterranean Sea, and North Africa. It shows an extended wave system. The images presented show that the upper-atmospheric layer is an efficient tracer of the dynamic processes at that level. Satellite-type views can be calculated without the drawback of looking downward from a satellite and measuring the numerous emissions from cities, oil fields, and other luminous sources.

Journal Article↗
PubMed2002

Role of oceanic air bubbles in atmospheric correction of ocean color imagery.

Ocean color is the radiance that emanates from the ocean because of scattering by chlorophyll pigments and particles of organic and inorganic origin. Air bubbles in the ocean also scatter light and thus contribute to the water-leaving radiance. This additional water-leaving radiance that is due to oceanic air bubbles could violate the black pixel assumption at near-infrared wavelengths and be attributed to chlorophyll in the visible. Hence, the accuracy of the atmospheric correction required for the retrieval of ocean color from satellite measurements is impaired. A comprehensive radiative transfer code for the coupled atmosphere--ocean system is employed to assess the effect of oceanic air bubbles on atmospheric correction of ocean color imagery. This effect is found to depend on the wavelength-dependent optical properties of oceanic air bubbles as well as atmospheric aerosols.

Journal Article↗
PubMed2003

Pitfalls in atmospheric correction of ocean color imagery: how should aerosol optical properties be computed?: Comment.

The Sea-Viewing Wide Field-of-View Sensor (SeaWiFS) experience suggests that in most situations the aerosol models presently in use for atmospheric correction of ocean color imagery are sufficient for this task. It has been shown [Appl. Opt. 41, 412 (2002)] that the top-of-atmosphere reflectances computed for more realistic aerosol models differ from those computed for presently used models but have not shown that they will yield a better atmospheric correction, e.g., through direct application to ocean color imagery. Thus they provide no evidence that the presently used aerosol models are inadequate, or that their use is a pitfall in atmospheric correction.

Comment↗
PubMed2004

Atmospheric optical turbulence over land in middle east coastal environments: prediction modeling and measurements.

Beam intensity scintillations, characterized by a refractive-index structure parameter and caused by variations of macrometeorological features of the coastal atmosphere such as air temperature, wind speed and direction, and relative humidity, are examined theoretically and experimentally. In our theoretical analysis we present two well-known models considered separately for over-water and over-land atmospheric optical communication or imaging channels. By means of comparison with our experiments carried out in midland coastal environments in southern and northern Israel, we show the limitations of the models to predict the refractive-index structure Cn2 parameter for both daytime and nighttime turbulent atmospheres in different coastal zone meteorological conditions. We also present an extension of an existing model with two different practical applications that, as is shown experimentally, can be a good predictor of Cn2 for optical atmospheric paths over midland coastal zones.

Journal Article↗
PubMed2005

Improved algorithm for calculations of Rayleigh-scattering optical depth in standard atmospheres.

Precise calculations of the total Rayleigh-scattering optical depth have been performed at 88 wavelengths ranging from 0.20 to 4.00 microm for the six well-known standard atmosphere models by integrating the volume Rayleigh-scattering coefficient along the vertical atmospheric path from sea level to a 120-km height. The coefficient was determined by use of an improved algorithm based on the Ciddor algorithm [Appl. Opt. 35, 1566 (1996)], extended by us over the 0.20-0.23-microm wavelength range to evaluate the moist air refractive index as a function of wavelength, air pressure, temperature, water-vapor partial pressure, and CO2 volume concentration. The King depolarization factor was also defined taking into account the moisture conditions of air. The results indicate that the influence of water vapor on Rayleigh scattering cannot be neglected at tropospheric altitudes: for standard atmospheric conditions represented in terms of the U.S. Standard Atmosphere (1976) model, the relative variations produced by water vapor in the Rayleigh scattering parameters at a 0.50-microm wavelength turn out to be equal to -0.10% in the moist air refractivity at sea level (where the water-vapor partial pressure is equal to approximately 7.8 hPa), -0.04% in the sea-level King factor, -0.24% in the sea-level Rayleigh-scattering cross section, and -0.06% in the Rayleigh-scattering optical depth.

Journal Article↗
PubMed2006

GMTR: two-dimensional geo-fit multitarget retrieval model for michelson interferometer for passive atmospheric sounding/environmental satellite observations.

We present a new retrieval model designed to analyze the observations of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS), which is on board the ENVironmental SATellite (ENVISAT). The new geo-fit multitarget retrieval model (GMTR) implements the geo-fit two-dimensional inversion for the simultaneous retrieval of several targets including a set of atmospheric constituents that are not considered by the ground processor of the MIPAS experiment. We describe the innovative solutions adopted in the inversion algorithm and the main functionalities of the corresponding computer code. The performance of GMTR is compared with that of the MIPAS ground processor in terms of accuracy of the retrieval products. Furthermore, we show the capability of GMTR to resolve the horizontal structures of the atmosphere. The new retrieval model is implemented in an optimized computer code that is distributed by the European Space Agency as "open source" in a package that includes a full set of auxiliary data for the retrieval of 28 atmospheric targets.

Journal Article↗
PubMed2006

Fourier domain preconditioned conjugate gradient algorithm for atmospheric tomography.

By 'atmospheric tomography' we mean the estimation of a layered atmospheric turbulence profile from measurements of the pupil-plane phase (or phase gradients) corresponding to several different guide star directions. We introduce what we believe to be a new Fourier domain preconditioned conjugate gradient (FD-PCG) algorithm for atmospheric tomography, and we compare its performance against an existing multigrid preconditioned conjugate gradient (MG-PCG) approach. Numerical results indicate that on conventional serial computers, FD-PCG is as accurate and robust as MG-PCG, but it is from one to two orders of magnitude faster for atmospheric tomography on 30 m class telescopes. Simulations are carried out for both natural guide stars and for a combination of finite-altitude laser guide stars and natural guide stars to resolve tip-tilt uncertainty.

Journal Article↗
PubMed2006

Validation of a vector version of the 6S radiative transfer code for atmospheric correction of satellite data. Part I: path radiance.

A vector version of the 6S (Second Simulation of a Satellite Signal in the Solar Spectrum) radiative transfer code (6SV1), which enables accounting for radiation polarization, has been developed and validated against a Monte Carlo code, Coulson's tabulated values, and MOBY (Marine Optical Buoy System) water-leaving reflectance measurements. The developed code was also tested against the scalar codes SHARM, DISORT, and MODTRAN to evaluate its performance in scalar mode and the influence of polarization. The obtained results have shown a good agreement of 0.7% in comparison with the Monte Carlo code, 0.2% for Coulson's tabulated values, and 0.001-0.002 for the 400-550 nm region for the MOBY reflectances. Ignoring the effects of polarization led to large errors in calculated top-of-atmosphere reflectances: more than 10% for a molecular atmosphere and up to 5% for an aerosol atmosphere. This new version of 6S is intended to replace the previous scalar version used for calculation of lookup tables in the MODIS (Moderate Resolution Imaging Spectroradiometer) atmospheric correction algorithm.

Journal Article↗
PubMed2003

Mode analysis of spreading of partially coherent beams propagating through atmospheric turbulence.

The spreading of partially coherent beams propagating through atmospheric turbulence is studied by use of the coherent-mode representation of the beams. Specifically, we consider partially coherent Gaussian Schell-model beams entering the atmosphere, and we examine the spreading of each coherent mode, represented by a Hermite-Gaussian function, on propagation. We find that in atmospheric turbulence the relative spreading of higher-order modes is smaller than that of lower-order modes, whereas the relative spreading of all order modes is the same as in free space. This modal behavior successfully explains why under certain circumstances partially coherent beams are less affected by atmospheric turbulence than are fully spatially coherent laser beams.

Journal Article↗