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1

EVALUATION OF SIGNIFICANT ANTHROPOGENIC SOURCES OF RADIATIVELY IMPORTANT TRACE GASES  

EPA Science Inventory

The report is an initial evaluation of significant anthropogenic sources of radiatively important trace gases. missions of greenhouse gases from human activities--including fossil fuel combustion, industrial/agricultural activities, and transportation--contribute to the increasin...

2

NATIONAL- AND STATE-LEVEL EMISSIONS ESTIMATES OF RADIATIVELY IMPORTANT TRACE GASES (RITGS) FROM ANTHROPOGENIC SOURCES  

EPA Science Inventory

The report documents the development of national- and state- level emissions estimates of radiatively important trace gases (RlTGs). Emissions estimates are presented for the principal anthropogenic sources of carbon dioxide (CO2), methane (CH4), chlorofluorocarbons (CFCs), and o...

3

Radiative heat transfer in high-temperature gases - Handbook  

Microsoft Academic Search

The principal problems in physics, gas dynamics, and applied fields where radiative heat transfer is of major importance are reviewed, and the existing methods for calculating radiative transfer in heated gases are examined. Particular attention is given to the asymptotic integral method of partial characteristics which makes it possible to achieve substantial savings in computer time by separately calculating the

I. F. Golovnev; V. P. Zamuraev; S. S. Katsnelson; G. A. Kovalskaia; V. G. Sevastianenko; R. I. Soloukhin

1984-01-01

4

Aerodynamics of Gases and Interaction with Radiation.  

National Technical Information Service (NTIS)

A very brief discussion is given of research in the following fields: Analytical methods in nonrelativistic field theory; point transforms in the quantum many body problem; singular perturbation theory in kinetic theory; light scattering from gases; varia...

E. P. Gross

1972-01-01

5

Greenhouse gases dissolved in soil solution - often ignored, but important?  

NASA Astrophysics Data System (ADS)

Flux measurements of climate-relevant trace gases from soils are frequently undertaken in contemporary ecosystem studies and substantially contribute to our understanding of greenhouse gas balances of the biosphere. While the great majority of such investigations builds on closed chamber and eddy covariance measurements, where upward gas fluxes to the atmosphere are measured, fewest concurrently consider greenhouse gas dissolution in the seepage and leaching of dissolved gases via the vadose zone to the groundwater. Here we present annual leaching losses of dissolved N2O and CO2 from arable, grassland, and forest lysimeter soils from three sites differing in altitude and climate. We aim to assess their importance in comparison to direct N2O emission, soil respiration, and further leaching parameters of the C- and N cycle. The lysimeters are part of the Germany-wide lysimeter network initiative TERENO-SoilCan, which investigates feedbacks of climate change to the pedosphere on a long-term scale. Soil water samples were collected weekly from different depths of the profiles by means of suction cups. A laboratory pre-experiment proved that no degassing occurred under those sampling conditions. We applied the headspace equilibration technique to determine dissolved gas concentrations by gas chromatography. The seepage water of all lysimeters was consistently supersaturated with N2O and CO2 compared to water equilibrated ambient air. In terms of N2O, leaching losses increased in the ascending order forest, grassland, and arable soils, respectively. In case of the latter soils, we observed a strong variability of N2O, with dissolved concentrations up to 23 ?g N L-1. However, since seepage discharge of the arable lysimeters was comparatively small and mostly limited to the hydrological winter season, leached N2O appeared to be less important than direct N2O emissions. In terms of dissolved CO2,our measurements revealed considerable leaching losses from the mountainous forest and grassland soils, based on concentrations up to 24 mg C L-1 and high seepage discharge. Such losses turned out to be similarly important like soil respiration, particularly during winter when temperature-dependent soil respiration declined. In conclusion, the results of the first year of our measurements provide evidence that dissolved greenhouse gases should be considered in studies which aim to assess full greenhouse gas balances, particularly in ecosystems where hydrological conditions favour microbial activity and high leaching losses.

Weymann, Daniel; Brueggemann, Nicolas; Puetz, Thomas; Vereecken, Harry

2014-05-01

6

Aerodynamics of Gases and Interaction with Radiation.  

National Technical Information Service (NTIS)

The report very briefly describes the results of a year's research. A theory of the collision broadening of the rotational spectrum of gases has been published. It can be used to analyze experimental results. Work was carried out on the moment method in k...

E. P. Gross

1973-01-01

7

Radiative forcings for 28 potential Archean greenhouse gases  

NASA Astrophysics Data System (ADS)

Despite reduced insolation in the late Archean, evidence suggests a warm climate which was likely sustained by a stronger greenhouse effect, the so-called Faint Young Sun Problem (FYSP). CO2 and CH4 are generally thought to be the mainstays of this enhanced greenhouse, though many other gases have been proposed. We present high accuracy radiative forcings for CO2, CH4 and 26 other gases, performing the radiative transfer calculations at line-by-line resolution and using HITRAN 2012 line data for background pressures of 0.5, 1, and 2 bar. For CO2 to resolve the FYSP alone, 0.21 bar is needed with 0.5 bar of atmospheric pressure, 0.13 bar with 1 bar of atmospheric pressures, or 0.07 bar with 2 bar of atmospheric pressure. For CH4, we find that near-infrared absorption is much stronger than previously thought, arising from updates to the HITRAN database. CH4 radiative forcing peaks at 10.3, 9, or 8.3 W m-2 for background pressures of 0.5, 1 or 2 bar, likely limiting the utility of CH4 for warming the Archean. For the other 26 HITRAN gases, radiative forcings of up to a few to 10 W m-2 are obtained from concentrations of 0.1-1 ppmv for many gases. We further calculate the reduction of radiative forcing due to gas overlap for the 20 strongest gases. We recommend the forcings provided here be used both as a first reference for which gases are likely good greenhouse gases, and as a standard set of calculations for validation of radiative forcing calculations for the Archean.

Byrne, B.; Goldblatt, C.

2014-05-01

8

Handbook of infrared radiation from combustion gases  

NASA Technical Reports Server (NTRS)

The treatment of radiant emission and absorption by combustion gases are discussed. Typical applications include: (1) rocket combustion chambers and exhausts, (2) turbojet engines and exhausts, and (3) industrial furnaces. Some mention is made of radiant heat transfer problems in planetary atmospheres, in stellar atmospheres, and in reentry plasmas. Particular consideration is given to the temperature range from 500K to 3000K and the pressure range from 0.001 atmosphere to 30 atmospheres. Strong emphasis is given to the combustion products of hydrocarbon fuels with oxygen, specifically to carbon dioxide, water vapor, and carbon monoxide. In addition, species such as HF, HC1, CN, OH, and NO are treated.

Ludwig, C. B.; Malkmus, W.; Reardon, J. E.; Thomson, J. A. L.; Goulard, R. (editor)

1973-01-01

9

Radiation interactions in high-pressure gases  

SciTech Connect

This article is on basic radiation interaction processes in dense fluids and on interphase studies aiming at the interfacing of knowledge on radiation interaction processes in the gaseous and the liquid state of matter. It is specifically focused on the effect of the density and nature of the medium on electron production in irradiated fluids and on the state, energy, transport, and attachment of slow excess electrons in dense fluids especially dielectric liquids which possess excess-electron conduction bands (V{sub 0} < 0 eV). Studies over the past two decades have shown that the interactions of low-energy electrons with molecules embedded in dense media depend not only on the molecules themselves and their internal state of excitation, but also on the electron state and energy in -- and the nature and density of -- the medium in which the interactions occur.

Christophorou, L.G. (Oak Ridge National Lab., TN (USA) Tennessee Univ., Knoxville, TN (USA))

1990-01-01

10

Radiative Importance of Aerosol-Cloud Interaction  

NASA Technical Reports Server (NTRS)

Aerosol particles are input into the troposphere by biomass burning, among other sources. These aerosol palls cover large expanses of the earth's surface. Aerosols may directly scatter solar radiation back to space, thus increasing the earth's albedo and act to cool the earth's surface and atmosphere. Aerosols also contribute to the earth's energy balance indirectly. Hygroscopic aerosol act as cloud condensation nuclei (CCN) and thus affects cloud properties. In 1977, Twomey theorized that additional available CCN would create smaller but more numerous cloud droplets in a cloud with a given amount of liquid water. This in turn would increase the cloud albedo which would scatter additional radiation back to space and create a similar cooling pattern as the direct aerosol effect. Estimates of the magnitude of the aerosol indirect effect on a global scale range from 0.0 to -4.8 W/sq m. Thus the indirect effect can be of comparable magnitude and opposite in sign to the estimates of global greenhouse gas forcing Aerosol-cloud interaction is not a one-way process. Just as aerosols have an influence on clouds through the cloud microphysics, clouds have an influence on aerosols. Cloud droplets are solutions of liquid water and CCN, now dissolved. When the cloud droplet evaporates it leaves behind an aerosol particle. This new particle does not have to have the same properties as the original CCN. In fact, studies show that aerosol particles that result from cloud processing are larger in size than the original CCN. Optical properties of aerosol particles are dependent on the size of the particles. Larger particles have a smaller backscattering fraction, and thus less incoming solar radiation will be backscattered to space if the aerosol particles are larger. Therefore, we see that aerosols and clouds modify each other to influence the radiative balance of the earth. Understanding and quantifying the spatial and seasonal patterns of the aerosol indirect forcing may have even greater consequences. Presently we know that through the use of fossil fuel and land-use changes we have increased the concentration of greenhouse gases in the atmosphere. In parallel, we have seen a modest increase of global temperature in the last century. These two observations have been linked as cause and effect by climate models, but this connection is still experimentally not verified. The spatial and seasonal distribution of aerosol forcing is different from that of greenhouse gases, thus generating a different spatial fingerprint of climate change. This fingerprint was suggested as a method to identify the response of the climate system to anthropogenic forcing of greenhouse gases and aerosol. The aerosol fingerprint may be the only way to firmly establish the presence (or absence) of human impact on climate. Aerosol-cloud interaction through the indirect effect will be an important component of establishing this fingerprint.

Tsay, Si-Chee

1999-01-01

11

Research on the Photon Absorption Processes of Gases Important in the Upper Atmosphere.  

National Technical Information Service (NTIS)

The results of investigations into the absorption processes of gases important in upper atmosphere chemistry and physics are presented. The principle region studied in the vacuum ultraviolet at wavelengths less than 3000 A. Methods of producing the OH rad...

J. L. Roebber

1970-01-01

12

Synthetic Lorentz force in classical atomic gases via Doppler effect and radiation pressure  

NASA Astrophysics Data System (ADS)

We theoretically predict synthetic Lorentz force for classical (cold) atomic gases, which is based on the Doppler effect and radiation pressure. A fairly spatially uniform and strong force can be constructed for gases in macroscopic volumes of several cubic millimeters and more. This opens the possibility to mimic classical charged gases in magnetic fields in cold-atom experiments.

Dub?ek, T.; Šanti?, N.; Juki?, D.; Aumiler, D.; Ban, T.; Buljan, H.

2014-06-01

13

Modeling of 3-D non-gray gases radiation by coupling the finite volume method with weighted sum of gray gases model  

Microsoft Academic Search

A new model and code for radiative heat transfer based on the numerical solution of the radiative transfer equation by finite volume method in 3-D Cartesian coordinates coupled with weighted sum of gray gases model (WSGGM) is developed. The Smith’s WSGG model with 4 and 5 gray gases is used, but any other gas radiative properties model can be incorporated.

D. N. Trivic

2004-01-01

14

Greenhouse Gases in Intensive Agriculture: Contributions of Individual Gases to the Radiative Forcing of the Atmosphere  

Microsoft Academic Search

Agriculture plays a major role in the global fluxes of the greenhouse gases carbon dioxide, nitrous oxide, and methane. From 1991 to 1999, we measured gas fluxes and other sources of global warming potential (GWP) in cropped and nearby unmanaged ecosystems. Net GWP (grams of carbon dioxide equivalents per square meter per year) ranged from 110 in our conventional tillage

G. Philip Robertson; Eldor A. Paul; Richard R. Harwood

2000-01-01

15

Gage measures total radiation, including vacuum UV, from ionized high-temperature gases  

NASA Technical Reports Server (NTRS)

Transient-heat transfer gage measures the total radiation intensity from vacuum ultraviolet and ionized high temperature gases. The gage includes a sensitive piezoelectric crystal that is completely isolated from any ionized flow and vacuum ultraviolet irradiation.

Wood, A. D.

1969-01-01

16

A Hypothesis on Biological Protection from Space Radiation Through the Use of Therapeutic Gases  

NASA Technical Reports Server (NTRS)

This slide presentation proposes a hypothesis to use therapeutic gases in space to enhance the biological protection for astronauts from space radiation. The fundamental role in how radiation causes biological damage appears to be radiolysis, the dissociation of water by radiation. A chain of events appears to cause molecular and biological transformations that ultimately manifest into medical diseases. The hypothesis of this work is that applying medical gases may increase resistance to radiation, by possessing the chemical properties that effectively improve the radical scavenging and enhance bond repair and to induce biological processes which enhance and support natural resistance and repair mechanisms.

Schoenfeld, Michael

2011-01-01

17

A Hypothesis on Biological Protection from Space Radiation Through the Use of New Therapeutic Gases  

NASA Technical Reports Server (NTRS)

Radiation exposure to astronauts could be a significant obstacle for long duration manned space exploration because of current uncertainties regarding the extent of biological effects. Furthermore, concepts for protective shielding also pose a technically challenging issue due to the nature of cosmic radiation and current mass and power constraints with modern exploration technology. The concern regarding exposure to cosmic radiation is the biological damage it induces. As damage is associated with increased oxidative stress, it is important and would be enabling to mitigate and/or prevent oxidative stress prior to the development of clinical symptoms and disease. This paper hypothesizes a "systems biology" approach in which a combination of chemical and biological mitigation techniques are used conjunctively. It proposes using new, therapeutic, medical gases as both chemical radioprotectors for radical scavenging and biological signaling molecules for management of the body s response to exposure. From reviewing radiochemistry of water, biological effects of CO, H2, NO, and H2S gas, and mechanisms of radiation biology, it is concluded that this approach may have great therapeutic potential for radiation exposure. Furthermore, it also appears to have similar potential for curtailing the pathogenesis of other diseases in which oxidative stress has been implicated including, cardiovascular disease, cancer, chronic inflammatory disease, hypertension, ischemia/reperfusion injury, acute respiratory distress syndrome, parkinson s and alzheimer s disease, cataracts, and aging

Schoenfeld, Michael P.; Ansari,Rafat R.; Nakao, Atsunori; Wink, David

2011-01-01

18

A Hypothesis on Biological Protection from Space Radiation Through the Use of New Therapeutic Gases  

NASA Technical Reports Server (NTRS)

Radiation exposure to astronauts could be a significant obstacle for long duration manned space exploration because of current uncertainties regarding the extent of biological effects. Furthermore, concepts for protective shielding also pose a technically challenging issue due to the nature of cosmic radiation and current mass and power constraints with modern exploration technology. The concern regarding exposure to cosmic radiation is the biological damage it induces. As damage is associated with increased oxidative stress, it is important and would be enabling to mitigate and/or prevent oxidative stress prior to the development of clinical symptoms and disease. This paper hypothesizes a "systems biology" approach in which a combination of chemical and biological mitigation techniques are used conjunctively. It proposes using new, therapeutic, medical gases as both chemical radioprotectors for radical scavenging and biological signaling molecules for management of the body s response to exposure. From reviewing radiochemistry of water, biological effects of CO, H2, NO, and H2S gas, and mechanisms of radiation biology, it is concluded that this approach may have great therapeutic potential for radiation exposure. Furthermore, it also appears to have similar potential for curtailing the pathogenesis of other diseases in which oxidative stress has been implicated including cardiovascular disease, cancer, chronic inflammatory disease, hypertension, ischemia/reperfusion injury, acute respiratory distress syndrome, Parkinson s and Alzheimer s disease, cataracts, and aging.

Schoenfeld, Michael P.; Ansari, Rafat R.; Nakao, Atsunori; Wink, David

2011-01-01

19

Radiative Forcing by Long-Lived Greenhouse Gases: Calculations with the AER Radiative Transfer Models  

SciTech Connect

A primary component of the observed, recent climate change is the radiative forcing from increased concentrations of long-lived greenhouse gases (LLGHGs). Effective simulation of anthropogenic climate change by general circulation models (GCMs) is strongly dependent on the accurate representation of radiative processes associated with water vapor, ozone and LLGHGs. In the context of the increasing application of the Atmospheric and Environmental Research, Inc. (AER) radiation models within the GCM community, their capability to calculate longwave and shortwave radiative forcing for clear sky scenarios previously examined by the radiative transfer model intercomparison project (RTMIP) is presented. Forcing calculations with the AER line-by-line (LBL) models are very consistent with the RTMIP line-by-line results in the longwave and shortwave. The AER broadband models, in all but one case, calculate longwave forcings within a range of -0.20 to 0.23 W m{sup -2} of LBL calculations and shortwave forcings within a range of -0.16 to 0.38 W m{sup -2} of LBL results. These models also perform well at the surface, which RTMIP identified as a level at which GCM radiation models have particular difficulty reproducing LBL fluxes. Heating profile perturbations calculated by the broadband models generally reproduce high-resolution calculations within a few hundredths K d{sup -1} in the troposphere and within 0.15 K d{sup -1} in the peak stratospheric heating near 1 hPa. In most cases, the AER broadband models provide radiative forcing results that are in closer agreement with high 20 resolution calculations than the GCM radiation codes examined by RTMIP, which supports the application of the AER models to climate change research.

Collins, William; Iacono, Michael J.; Delamere, Jennifer S.; Mlawer, Eli J.; Shephard, Mark W.; Clough, Shepard A.; Collins, William D.

2008-04-01

20

Medically important solar ultraviolet A. Radiation measurements.  

PubMed

Results from a 6-year study of solar ultraviolet A (UVA) radiation measurements at the equatorial location of Penang (5 degrees N) are presented. On clear days, the diurnal flux reaches a very high dosage of about 3.0 x 10(-2) KWHM-2 around midday. The average daily total flux is in the range of 1.6 x 10(-1) KWHM-2 and does not change much seasonally. The high 83% cloud cover only reduces the incoming flux to about half. The radiation flux represents a lower limit of the incident UVA radiation applicable to much of the equatorial/tropical region. PMID:3391727

Ilyas, M; Abdul Aziz, D; Tajuddin, M R

1988-06-01

21

Radiation effects on insulating gases for the ITER NBI system  

Microsoft Academic Search

The radiation induced leakage current in dry air and SF6 has been measured as a function of dose rate, voltage, and electrode separation in order to assess the problem for the ITER NBI system insulating gas. The results indicate that for the high voltages involved, the leakage current is a function of the gas volume rather than the electrode separation.

E. R. Hodgson; A. Moroño

1998-01-01

22

Knudsen cell: Investigations about the uptake of important traces gases on ambient airborne mineral dust  

NASA Astrophysics Data System (ADS)

Mineral dust constitutes one of the largest mass fractions of natural aerosol. Its emission is estimated between 800 - 2000 Tg/a]. The dust is emitted through sand and dust storms in the arid regions of our planet, in particular by the great desserts such as the Sahara. The complex chemical composition of mineral dust is similar to crust material, because the dust is produced by soil erosion. The main components of mineral dust are SiO2 and Al2O3, whereas the active oxides (Fe2O3, TiO2) show some variety in content due to the dust source region. Mineral dust particles can be transported over several 1000 km and during its transport the surface can be changed by the uptake of water vapor and trace gases. On such modified surfaces homo- and heterogeneous reactions can occur. Trace gas uptakes play an important role in atmospheric chemistry as sinks or sources for several gaseous species. Hence, it is necessary to study these reactions. Among several experimental setups, the Knudsen cell is one of the promising tools to study reactive uptakes from the gas phase and the release of products formed by dust surface-mediated reactions. The Knudsen cell, implemented by Golden et al. in 1975, is a high vacuum flow reactor operating under molecular flow conditions, i.e., gas-wall collisions are highly preferred over gas-gas collisions. Despite several Knudsen cell studies examining the reaction between different traces gases and model dust surfaces constituted of not more than a few components, no measurements utilizing collected ambient mineral dust are done so far. For a better understanding of the chemistry on mineral dust surfaces gas uptake measurements will be done with a Knudsen cell. The first measurements are done with isopropanol on TiO2. Afterwards there are studies with different substrates like, Al2O3 (?- and ?-phase), FeO2, Arizona test dust, air collected mineral dust from the Cap Verde islands. In the beginning SO2, NO2 and HNO3 will be used.

Horn, Sabrina; Herrmann, Hartmut

2013-04-01

23

Radiative forcing by well-mixed greenhouse gases: Estimates from climate models in the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4)  

Microsoft Academic Search

The radiative effects from increased concentrations of well-mixed greenhouse gases (WMGHGs) represent the most significant and best understood anthropogenic forcing of the climate system. The most comprehensive tools for simulating past and future climates influenced by WMGHGs are fully coupled atmosphere-ocean general circulation models (AOGCMs). Because of the importance of WMGHGs as forcing agents it is essential that AOGCMs compute

W. D. Collins; V. Ramaswamy; M. D. Schwarzkopf; Y. Sun; R. W. Portmann; Q. Fu; S. E. B. Casanova; J.-L. Dufresne; D. W. Fillmore; P. M. D. Forster; V. Y. Galin; L. K. Gohar; W. J. Ingram; D. P. Kratz; M.-P. Lefebvre; J. Li; P. Marquet; V. Oinas; Y. Tsushima; T. Uchiyama; W. Y. Zhong

2006-01-01

24

Greenhouse gases, radiative forcing, global warming potential and waste management--an introduction.  

PubMed

Management of post-consumer solid waste contributes to emission of greenhouse gases (GHGs) representing about 3% of global anthropogenic GHG emissions. Most GHG reporting initiatives around the world utilize two metrics proposed by the Intergovernmental Panel on Climate Change (IPCC): radiative forcing (RF) and global warming potential (GWP). This paper provides a general introduction of the factors that define a GHG and explains the scientific background for estimating RF and GWP, thereby exposing the lay reader to a brief overview of the methods for calculating the effects of GHGs on climate change. An objective of this paper is to increase awareness that the GWP of GHGs has been re-adjusted as the concentration and relative proportion of these GHGs has changed with time (e.g., the GWP of methane has changed from 21 to 25 CO(2)-eq). Improved understanding of the indirect effects of GHGs has also led to a modification in the methodology for calculating GWP. Following a presentation of theory behind GHG, RF and GWP concepts, the paper briefly describes the most important GHG sources and sinks in the context of the waste management industry. The paper serves as a primer for more detailed research publications presented in this special issue of Waste Management & Research providing a technology-based assessment of quantitative GHG emissions from different waste management technologies. PMID:19748948

Scheutz, Charlotte; Kjeldsen, Peter; Gentil, Emmanuel

2009-11-01

25

Planetary Formation and Evolution Revealed with a Saturn Entry Probe: The Importance of Noble Gases  

Microsoft Academic Search

The determination of Saturn's atmospheric noble gas abundances are critical to understanding the formation and evolution of Saturn, and giant planets in general. These measurements can only be performed with an entry probe. A Saturn probe will address whether enhancement in heavy noble gases, as was found in Jupiter, are a general feature of giant planets, and their ratios will

Jonathan J. Fortney; Kevin Zahnle; Isabelle Baraffe; Adam Burrows; Sarah E. Dodson-Robinson; Gilles Chabrier; Tristan Guillot; Ravit Helled; Franck Hersant; William B. Hubbard; Jack J. Lissauer; Mark S. Marley

2009-01-01

26

Importance of greenhouse gases other than carbon dioxide and other possible differences between various fuels.  

National Technical Information Service (NTIS)

An attempt has been made to assess factors that indicate how various fuels affect the climate. In these factors emissions of carbon dioxide, methane and nitrous oxide are weighed together with reference to the direct and indirect effects of these gases on...

T. Levander

1989-01-01

27

Interconversion of biologically important carboxylic acids by radiation  

NASA Technical Reports Server (NTRS)

The interconversion of a group of biologically important polycarboxylic acids (acetic, fumaric, malic, malonic, succinic, citric, isocitric, tricarballylic) under gamma-ray or ultraviolet radiation was investigated. The formation of high molecular weight compounds was observed in all cases. Succinic acid was formed in almost all radiolysis experiments. Citric, malonic, and succinic acids appeared to be relatively insensitive to radiation. Interconversion of the polycarboxylic acids studied may have occurred under the effect of radiation in the prebiotic earth.

Negron-Mendoza, A.; Ponnamperuma, C.

1978-01-01

28

A Hypothesis on Biological Protection from Space Radiation Through the Use of New Therapeutic Gases as Medical Counter Measures  

NASA Technical Reports Server (NTRS)

Radiation exposure to astronauts could be a significant obstacle for long duration manned space exploration because of current uncertainties regarding the extent of biological effects. Furthermore, concepts for protective shielding also pose a technically challenging issue due to the nature of cosmic radiation and current mass and power constraints with modern exploration technology. The concern regarding exposure to cosmic radiation is the biological damage it induces. As damage is associated with increased oxidative stress, it is important and would be enabling to mitigate and/or prevent oxidative stress prior to the development of clinical symptoms and disease. This paper hypothesizes a "systems biology" approach in which a combination of chemical and biological mitigation techniques are used conjunctively. It proposes using new, therapeutic, medical gases as both chemical radioprotectors for radical scavenging and biological signaling molecules for management of the body s response to exposure. From reviewing radiochemistry of water, biological effects of CO, H2, NO, and H2S gas, and mechanisms of radiation biology, it is concluded that this approach may have great therapeutic potential for radiation exposure. Furthermore, it also appears to have similar potential for curtailing the pathogenesis of other diseases in which oxidative stress has been implicated including cardiovascular disease, cancer, chronic inflammatory disease, hypertension, ischemia/reperfusion injury, acute respiratory distress syndrome, Parkinson s and Alzheimer s disease, cataracts, and aging.

Schoenfeld, Michael P.; Ansari, Rafat R.; Nakao, Atsunori; Wink, David

2012-01-01

29

Studies of multiphoton production of vacuum-ultraviolet radiation in the rare gases  

NASA Astrophysics Data System (ADS)

Measurements of the vacuum-ultraviolet radiation produced by intense ultraviolet irradiation of rare gases have revealed the copious presence of both harmonic radiation and fluorescence from excited levels. The highest harmonic observed was the seventeenth in Ne, the shortest wavelength ever produced by that means. Strong fluorescence was seen from ions of Ar, Kr, and Xe, with the shortest wavelengths observed being below 12 nm. Furthermore, radiation from inner-shell excited configurations in Xe, specifically the 4d9 5s 5p to 4d10 5s manifold of Xe(7+) at about 17.7 nm, was detected. These experimental findings, in alliance with other studies concerning multielectron processes, give evidence for a role of electron correlations in a direct nonlinear process of inner-shell excitation.

McPherson, A.; Gibson, G.; Jara, H.; Johann, U.; Luk, T. S.

1987-04-01

30

Radiative interaction between driver and driven gases in an arc-driven shock tube  

NASA Astrophysics Data System (ADS)

An electric-arc driven shock tube was operated with hydrogen as the driven gas and either hydrogen or helium as the driver gas. The electron density was measured behind the primary shock wave spectroscopically from the width of the hydrogen beta line. The intensity of the radiation produced by the driver and driven gases and directed along the axis of the shock tube was measured with a photomultiplier tube. The temperatures behind the primary shock wave were 3 to 4 times those calculated from the Rankine-Hugoniot relations. A proposed explanation for this difference is developed, involving strong heating of the driven gas at early times due to higher shock velocities and radiative energy transfer from the driver arc. The electron density ahead of the shock wave agreed roughly with the calculation based on the precursor phenomenon due to radiative transfer.

Bogdanoff, D. W.; Park, C.

31

Laser driven high energy density radiative blast waves launched in clustered gases  

NASA Astrophysics Data System (ADS)

Intense lasers deposit energy efficiently in clustered gases creating hot plasma with low density, conditions ideal for launching radiative blast waves (BWs) of interest for laboratory astrophysics (LA). We report measurements in a range of gases irradiated by the Astra-Gemini laser with energies >10J. Optical imaging, self emission and temporally resolved x-ray spectra are used to characterise BW evolution. The high repetition rate of the laser allows us to explore the influence of atomic number and density on the BW dynamics. Altering the emitted radiation and opacity of the medium has a strong effect on the BW profile and energy loss. Strongly radiative BWs exhibit shell thinning, increasing their susceptibility to instabilities. We have demonstrated the onset of a velocity instability, driven by the exchange of energy between the shock and precursor in krypton BWs. We discuss the threshold conditions for this behaviour and the potential to study spatial shock front instabilities. Our results will be compared to simulations and analytical calculations with a view to designing scalable LA experiments.

Olsson-Robbie, Stefan; Doyle, Hugo; Lowe, Hazel; Price, Chris; Bigourd, Damien; Patankar, Siddharth; Mecseki, Katalin; Booth, Nicola; Scott, Robbie; Moore, Alastair; Hohenberger, Matthias; Rodriguez, Rafael; Gumbrell, Edward; Symes, Daniel; Smith, Roland

2012-10-01

32

Emission of Greenhouse Gases in the Netherlands.  

National Technical Information Service (NTIS)

Climate change has become an important component of Dutch environmental and energy policies. Human induced climate change has become an important issue. It is caused by the accumulation of a number of radiatively active trace gases in the atmosphere. Unti...

G. J. van den Born A. F. Bouwman J. G. J. Olivier R. J. Swart

1991-01-01

33

The importance of atmospheric chemistry in the calculation of radiative forcing on the climate system  

SciTech Connect

An interactive two-dimensional model of the troposphere, stratosphere, and mesosphere, in which dynamics, radiation, and chemistry are treated interactively, is used to investigate the anthropogenic changes in the steady state chemical composition of the atmosphere since preindustrial times and to assess the associated changes in radiative forcing on climate. The perturbations in the atmospheric oxidation capacity due to anthropogenic emissions of source gases are found to be significant. In the troposphere, an ozone increase of 80-120% at northern midlatitudes and a global decrease of 10-20% in the OH concentration since the preindustrial period are calculated. In the polar lower stratosphere of the southern hemisphere, an ozone depletion since preindustrial times reaching more than 60% during spring is calculated as a result of rapid catalytical destruction of ozone by chlorine radicals in the presence of polar stratospheric clouds. Particular attention is given to the induced changes in radiative forcing. These results stress the potentially important role of chemical feedbacks on climate and indicate that the direct forcing associated with increasing concentrations of greenhouse gases is enhanced by about 30% when these feedbacks are taken into account. On a global average basis, the greenhouse effect of tropospheric ozone represents approximately 17% of the total radiative perturbation. This forcing is characterized by a strong latitudinal dependence, peaking at midlatitudes in the northern hemisphere. The importance of indirect climate forcings by stratospheric ozone (including local cooling of the stratosphere) is confirmed. It is found that the net (solar + infrared) indirect effect of stratospheric ozone changes is to increase the chlorofluorocarbon direct radiative forcing.

Hauglustaine, D.A.; Granier, C.; Brasseur, G.P.; Megie, G. (CNRS (France) National Center for Atmospheric Research, Boulder, CO (United States))

1994-01-01

34

A comparison between weighted sum of gray gases and statistical narrow-band radiation models for combustion applications  

SciTech Connect

The weighted sum of gray gases (WSGG) and the statistical narrow-band (SNB) models are implemented for radiative transfer calculations in realistic combustion gas mixtures and their results are compared. The WSGG model parameters are generated from SNB emissivity calculations in the [300, 2500 K] temperature range for a partial pressure ratio p[sub w]/p[sub c] = 2. In addition, the same methods are used for the resolution of the transfer equation associated with both models. Comparisons are made for the cases of planar geometry and an axisymmetrical methane--oxygen furnace. When the gas mixture is practically isothermal and surrounded by cold walls, small errors are introduced by the use of the WSGG model. On the other hand, in the case of significant temperature gradients, the inaccurate representation of gas absorptivities by the WSGG model leads to important errors.

Soufiani, A. (Ecole Centrale Paris, Chatenay-Malabry (France). Lab. d'Energetique Moleculaire et Macroscopique); Djavdan, E. (Centre de Recherche Claude-Delorme, Jouy-en-Josas (France))

1994-05-01

35

Diurnal characteristics of surface level O3 and other important trace gases in New England  

NASA Astrophysics Data System (ADS)

Data obtained from spring 2001 to summer 2003 in New England by the Atmospheric Investigation, Regional Modeling, Analysis and Prediction (AIRMAP) program were used to document the diurnal characteristics of O3, CO2, NO, and during selected intervals hydrocarbon and oxygenated species. The diurnal cycles of O3 and oxygenated species showed a monotonic rise in mixing ratio following sunrise (replenishment) that was mirrored by nighttime removal (depletion) under the nocturnal inversion. The median depletion rate of O3 was 4.9 ppbv h-1 compared to a replenishment rate of 6.2 ppbv h-1. The significant and rapid loss of O3 at night combined with an anthropogenic hydrocarbon signature dominated by a vehicular source led us to the hypothesis that nocturnal O3 depletion represented the combined effects of dry deposition and titration by NO released from mobile sources. Nighttime removal of O3 averaged 31 ppbv (median of 27 ppbv), with ˜11 ppbv due to dry deposition and ˜20 ppbv loss by titration with NO and NO2. The seasonally averaged diurnal cycles of O3 and NO were very similar from year to year, indicating that although there was large variability in the daily levels of these species, their sources/sinks were quite consistent. Moreover, CO2 and selected hydrocarbons exhibited a diurnal cycle opposite to that of O3, with the highest mixing ratios occurring at night. The diurnal cycles of oxygenated compounds such as methanol, acetaldehyde, methyl ethyl ketone, acetone + propanal, methyl vinyl ketone + methacrolein were investigated for a 2 day time period in July 2003. Our data are among the first to illustrate the diurnal cycle of these compounds. We used these species to demonstrate the importance of vertical mixing in driving the diurnal cycle of ground level O3 in New England. Day/night ratios ranged from 2.3 for acetone + propanal to 11 for methyl vinyl ketone + methacrolein. Deposition velocities of 0.5-1 m s-1 were estimated for these species, which are significantly higher than values used in many models. Such efficient removal may have important implications for the chemical impact of these species, at least on a regional scale.

Talbot, Robert; Mao, Huiting; Sive, Barkley

2005-05-01

36

Observation-based assessment of stratospheric fractional release, lifetimes, and Ozone Depletion Potentials of ten important source gases  

NASA Astrophysics Data System (ADS)

Estimates of the recovery time of stratospheric ozone heavily rely on the exact knowledge of the processes that lead to the decomposition of the relevant halogenated source gases. Crucial parameters in this context are Fractional Release Factors (FRFs) as well as stratospheric lifetimes and Ozone Depletion Potentials (ODPs). We here present data from the analysis of air samples collected between 2009 and 2011 on board research aircraft flying in the mid- and high latitudinal stratosphere and infer the above-mentioned parameters for ten major source gases:CFCl3 (CFC-11), CF2Cl2 (CFC-12), CF2ClCFCl2(CFC-113), CCl4 (carbon tetrachloride),CH3CCl3 (methyl chloroform), CHF2Cl (HCFC-22), CH3CFCl2 (HCFC-141b), CH3CF2Cl (HCFC-142b), CF2ClBr (H-1211), and CF3Br (H-1301). The inferred correlations of their FRFs with mean ages of air reveal less decomposition as compared to previous studies for most compounds. When using the calculated set of FRFs to infer equivalent stratospheric chlorine we find a reduction of more than 20% as compared to the values inferred in the most recent Scientific Assessment of Ozone Depletion by the World Meteorological Organisation (WMO, 2011). We also note that FRFs and their correlations with mean age are not generally time-independent as often assumed. The stratospheric lifetimes were calculated relative to that of CFC-11. Within our uncertainties the inferred ratios between lifetimes agree with those between stratospheric lifetimes from recent WMO reports except for CFC-11, CFC-12 and CH3CCl3. Finally we calculate lower ODPs than WMO for six out of ten compounds with changes most pronounced for the three HCFCs. Collectively these newly calculated values may have important implications for the severity and recovery time of stratospheric ozone loss.

Laube, J. C.; Keil, A.; Bönisch, H.; Engel, A.; Röckmann, T.; Volk, C. M.; Sturges, W. T.

2012-10-01

37

Observation-based assessment of stratospheric fractional release, lifetimes, and ozone depletion potentials of ten important source gases  

NASA Astrophysics Data System (ADS)

Estimates of the recovery time of stratospheric ozone heavily rely on the exact knowledge of the processes that lead to the decomposition of the relevant halogenated source gases. Crucial parameters in this context are fractional release factors (FRFs) as well as stratospheric lifetimes and ozone depletion potentials (ODPs). We here present data from the analysis of air samples collected between 2009 and 2011 on board research aircraft flying in the mid- and high-latitude stratosphere and infer the above-mentioned parameters for ten major source gases: CFCl3 (CFC-11), CF2Cl2 (CFC-12), CF2ClCFCl2 (CFC-113), CCl4 (carbon tetrachloride), CH3CCl3 (methyl chloroform), CHF2Cl (HCFC-22), CH3CFCl2 (HCFC-141b), CH3CF2Cl (HCFC-142b), CF2ClBr (H-1211), and CF3Br (H-1301). The inferred correlations of their FRFs with mean ages of air reveal less decomposition as compared to previous studies for most compounds. When using the calculated set of FRFs to infer equivalent stratospheric chlorine, we find a reduction of more than 20% as compared to the values inferred in the most recent Scientific Assessment of Ozone Depletion by the World Meteorological Organisation (WMO, 2011). We also note that FRFs and their correlations with mean age are not generally time-independent as often assumed. The stratospheric lifetimes were calculated relative to that of CFC-11. Within our uncertainties the ratios between stratospheric lifetimes inferred here agree with the values in recent WMO reports except for CFC-11, CFC-12 and CH3CCl3. Finally, we calculate lower ODPs than recommended by WMO for six out of ten compounds, with changes most pronounced for the three HCFCs. Collectively these newly calculated values may have important implications for the severity and recovery time of stratospheric ozone loss.

Laube, J. C.; Keil, A.; Bönisch, H.; Engel, A.; Röckmann, T.; Volk, C. M.; Sturges, W. T.

2013-03-01

38

Importance of Bladder Radioactivity for Radiation Safety in Nuclear Medicine  

PubMed Central

Objective: Most of the radiopharmaceuticals used in nuclear medicine are excreted via the urinary system. This study evaluated the importance of a reduction in bladder radioactivity for radiation safety. Methods: The study group of 135 patients underwent several organ scintigraphies [40/135; thyroid scintigraphy (TS), 30/135; whole body bone scintigraphy (WBS), 35/135; myocardial perfusion scintigraphy (MPS) and 30/135; renal scintigraphy (RS)] by a technologist within 1 month. In full and empty conditions, static bladder images and external dose rate measurements at 0.25, 0.50, 1, 1.5 and 2 m distances were obtained and decline ratios were calculated from these two data sets. Results: External radiation dose rates were highest in patients undergoing MPS. External dose rates at 0.25 m distance for TS, TKS, MPS and BS were measured to be 56, 106, 191 and 72 ?Sv h-1 for full bladder and 29, 55, 103 and 37 ?Sv h-1 for empty bladder, respectively. For TS, WBS, MPS and RS, respectively, average decline ratios were calculated to be 52%, 55%, 53% and 54% in the scintigraphic assessment and 49%, 51%, 49%, 50% and 50% in the assessment with Geiger counter. Conclusion: Decline in bladder radioactivity is important in terms of radiation safety. Patients should be encouraged for micturition after each scintigraphic test. Spending time together with radioactive patients at distances less than 1 m should be kept to a minimum where possible. Conflict of interest:None declared.

Gultekin, Salih Sinan; Sahmaran, Turan

2013-01-01

39

Importance of bladder radioactivity for radiation safety in nuclear medicine.  

PubMed

Objective: Most of the radiopharmaceuticals used in nuclear medicine are excreted via the urinary system. This study evaluated the importance of a reduction in bladder radioactivity for radiation safety. Methods: The study group of 135 patients underwent several organ scintigraphies [40/135; thyroid scintigraphy (TS), 30/135; whole body bone scintigraphy (WBS), 35/135; myocardial perfusion scintigraphy (MPS) and 30/135; renal scintigraphy (RS)] by a technologist within 1 month. In full and empty conditions, static bladder images and external dose rate measurements at 0.25, 0.50, 1, 1.5 and 2 m distances were obtained and decline ratios were calculated from these two data sets. Results: External radiation dose rates were highest in patients undergoing MPS. External dose rates at 0.25 m distance for TS, TKS, MPS and BS were measured to be 56, 106, 191 and 72 ?Sv h-1 for full bladder and 29, 55, 103 and 37 ?Sv h-1 for empty bladder, respectively. For TS, WBS, MPS and RS, respectively, average decline ratios were calculated to be 52%, 55%, 53% and 54% in the scintigraphic assessment and 49%, 51%, 49%, 50% and 50% in the assessment with Geiger counter. Conclusion: Decline in bladder radioactivity is important in terms of radiation safety. Patients should be encouraged for micturition after each scintigraphic test. Spending time together with radioactive patients at distances less than 1 m should be kept to a minimum where possible. Conflict of interest:None declared. PMID:24416625

Gültekin, Salih Sinan; Sahmaran, Turan

2013-12-01

40

Application of the Spectral Line-based Weighted-Sum-of-Gray-Gases model (SLWSGG) to the calculation of radiative heat transfer in steel reheating furnaces firing on low heating value gases  

NASA Astrophysics Data System (ADS)

The Spectral Line-based Weighted-Sum-of-Gray-Gases (SLWSGG) model is applied to calculate the gaseous radiative properties of the aero- or oxy-combustion products of low heating value gases issued from steel making process such as Blast Furnace Gas (BFG) as well as of high heating value gases such as Coke Oven Gas (COG) and conventional Natural Gas (NG). The comparison of total emissivities shows that the 3-gray-gases SLWSGG model is in very good agreement with the Hottel and Sarofim's database. The 3-gray-gases SLWSGG model is then integrated into AnsysFluent® Discrete Ordinates method under User Defined Function and CFD simulations are performed using these combined models. The simulations are done, with full combustion-radiation coupling, for steel reheating furnaces firing on three types of gases: BFG, COG and NG. The results are compared with the simulations realized with the 1-gray-gas WSGG model available in AnsysFluent®. The comparison shows that the 1-gray-gas WSGG model highly overestimates the steel discharging temperature as compared to the 3-gray-gases SLWSGG model. Significant temperature differences are observed between the two radiative models, i.e. 116°C, 55°C and 67°C for the BFG, COG and NG cases, respectively. It can be concluded that the 3-gray-gases SLWSGG model should be used to calculate the radiation heat transfer in large industrial furnaces with more accuracy not only for low heating value gases such as BFG but also for high heating value gases such as COG and NG.

Nguyen, P. D.; Danda, A.; Embouazza, M.; Gazdallah, M.; Evrard, P.; Feldheim, V.

2012-06-01

41

Importance of instantaneous radiative forcing for rapid tropospheric adjustment  

NASA Astrophysics Data System (ADS)

To better understand CFMIP/CMIP inter-model differences in rapid low cloud responses to CO2 increases and their associated effective radiative forcings, we examined the tropospheric adjustment of the lower tropospheric stability (LTS) in three general circulation models (GCMs): HadGEM2-A, MIROC3.2 medres, and MIROC5. MIROC3.2 medres showed a reduction in LTS over the sub-tropical ocean, in contrast to the other two models. This reduction was consistent with a temperature decrease in the mid-troposphere. The temperature decrease was mainly driven by instantaneous radiative forcing (RF) caused by an increase in CO2. Reductions in radiative and latent heating, due to clouds, and in adiabatic and advective heating, also contribute to the temperature decrease. The instantaneous RF in the mid-troposphere in MIROC3.2 medres is inconsistent with the results of line-by-line (LBL) calculations, and thus it is considered questionable. These results illustrate the importance of evaluating the vertical profile of instantaneous RF with LBL calculations; improved future model performance in this regard should help to increase our confidence in the tropospheric adjustment in GCMs.

Ogura, Tomoo; Webb, Mark J.; Watanabe, Masahiro; Lambert, F. Hugo; Tsushima, Yoko; Sekiguchi, Miho

2013-10-01

42

Development Of An Electronic Nose For Environmental Monitoring: Detection Of Specific Environmentally Important Gases At Their Odor Detection Threshold Concentration  

NASA Astrophysics Data System (ADS)

The use of a sensor array is demonstrated to be an effective approach to evaluate hazardous odor (or gas) emissions from industrial sites1. Therefore the possibility to use electronic noses for the prolonged survey of odor emissions from industrial sites is of particular interest for environmental monitoring purposes2. At the Olfactometric Laboratory of the Politecnico di Milano, in collaboration with Sacmi Group, Imola, an innovative electronic nose for the continuous monitoring of environmental odors is being developed. The aim of this work is to show the laboratory tests conducted to evaluate the capability of the electronic nose to recognize some specific environmentally important gases at their odor detection threshold concentration. The laboratory studies up to now focused on ammonia and butyric acid, those being compounds that can typically be found in the emissions from waste treatment plants, that may cause health effects when they exceed a given concentration level. The laboratory tests proved the sensors to be sensitive towards the considered compounds and the system to be capable of discriminating between odorous or non-odorous air, with a detection limit comparable with the detection limit of human nose.

Dentoni, Licinia; Capelli, Laura; Sironi, Selena; Del Rosso, Renato; Centola, Paolo; Della Torre, Matteo; Demattè, Fabrizio

2011-09-01

43

Solar Radiation Output Indices of Importance for Exospheric Properties  

NASA Astrophysics Data System (ADS)

The solar output in a broad spectral range, from X-rays to ultraviolet, significantly influences the distribution of hydrogen (H) atoms in the exosphere. All three populations—ballistic, satellite, and escaping atoms—are affected by solar radiation as it modifies the effective altitude and temperature of the exobase, controls to a large degree the dynamics of satellite atoms by radiation pressure, and contributes to atom losses. The Two Wide-angle imaging Neutral Atom Spectrometers (TWINS) mission stereoscopically images the magnetosphere in energetic neutral atom fluxes and additionally carries Lyman-alpha detectors (LADs) to investigate exospheric hydrogen. We use LAD measurements to obtain the global three-dimensional H distributions on a daily basis. The sequence of such distributions will enable studying of the exospheric response to the time-varying solar output. We show that the commonly used F10.7 index does not fully describe the solar conditions of importance to exospheric properties. We analyze the available indices F10.7, E10.7, S10.7, and Lyman-alpha which characterize the solar output from X-rays to ultraviolet. The characteristic times of processes governing atom injection, dynamics, and losses are different, which calls for the use of appropriate indices and their combinations. We discuss the available data sets, as well as the potential for study of exospheric response to variations in the solar output.

Bailey, J. J.; Gruntman, M.; Tobiska, W.

2010-12-01

44

Future Climate Impacts of Direct Radiative Forcing Anthropogenic Aerosols, Tropospheric Ozone, and Long-lived Greenhouse Gases  

NASA Technical Reports Server (NTRS)

Long-lived greenhouse gases (GHGs) are the most important driver of climate change over the next century. Aerosols and tropospheric ozone (O3) are expected to induce significant perturbations to the GHG-forced climate. To distinguish the equilibrium climate responses to changes in direct radiative forcing of anthropogenic aerosols, tropospheric ozone, and GHG between present day and year 2100, four 80-year equilibrium climates are simulated using a unified tropospheric chemistry-aerosol model within the Goddard Institute for Space Studies (GISS) general circulation model (GCM) 110. Concentrations of sulfate, nitrate, primary organic (POA) carbon, secondary organic (SOA) carbon, black carbon (BC) aerosols, and tropospheric ozone for present day and year 2100 are obtained a priori by coupled chemistry-aerosol GCM simulations, with emissions of aerosols, ozone, and precursors based on the Intergovernmental Panel on Climate Change (IPCC) Special Report on Emissions Scenario (SRES) A2. Changing anthropogenic aerosols, tropospheric ozone, and GHG from present day to year 2100 is predicted to perturb the global annual mean radiative forcing by +0.18 (considering aerosol direct effects only), +0.65, and +6.54 W m(sup -2) at the tropopause, and to induce an equilibrium global annual mean surface temperature change of +0.14, +0.32, and +5.31 K, respectively, with the largest temperature response occurring at northern high latitudes. Anthropogenic aerosols, through their direct effect, are predicted to alter the Hadley circulation owing to an increasing interhemispheric temperature gradient, leading to changes in tropical precipitation. When changes in both aerosols and tropospheric ozone are considered, the predicted patterns of change in global circulation and the hydrological cycle are similar to those induced by aerosols alone. GHG-induced climate changes, such as amplified warming over high latitudes, weakened Hadley circulation, and increasing precipitation over the Tropics and high latitudes, are consistent with predictions of a number of previous GCM studies. Finally, direct radiative forcing of anthropogenic aerosols is predicted to induce strong regional cooling over East and South Asia. Wintertime rainfall over southeastern China and the Indian subcontinent is predicted to decrease because of the increased atmospheric stability and decreased surface evaporation, while the geographic distribution of precipitation is also predicted to be altered as a result of aerosol-induced changes in wind flow.

Chen, Wei-Ting; Liao, Hong; Seinfeld, John H.

2007-01-01

45

Second Harmonic Generation of Self-Mode-Locked ??2-Laser Radiation in GaSe and GaSeS Crystals  

NASA Astrophysics Data System (ADS)

A TEA CO2 laser generating at the wavelength ? = 10.6 ?m in the modes of free lasing and self-mode-locking was used to obtain and compare second harmonic generation (SHG) in GaSe and GaSe0.7S0.3 crystals. With the self-mode-locked laser, a 5-times higher energy efficiency of SHG was obtained. The efficiency of SHG in the GaSe0.7S0.3 crystal and its second-order nonlinear susceptibility were estimated and compared with their values for undoped GaSe.

Genin, D. E.; Beloplotov, D. V.; Sitnikov, A. G.; Panchenko, A. N.; Sarkisov, S. Yu.; Chernyshov, A. I.

2014-03-01

46

Some issues important in developing basic radiation protection recommendations  

SciTech Connect

Presentations in this conference addressed various aspects of risk estimation, somatic effects, effects on the embryo-fetus, genetic impacts, non-stochastic effects, and implications for the NCRP program. Also included is the Eighth Lauriston S. Taylor Lecture, ''Limitation and Assessment in Radiation Protection,'' presented by Harold H. Rossi. Representatives from the Nuclear Regulatory Commission, Environmental Protection Agency, Center for Devices and Radiological Health, and Department of Energy participated in a Scientific Briefing Session entitled ''What the NCRP Should be Doing for Federal Agencies.'' The meeting closed with brief progress reports from NCRP scientific committees concerned with (1) Biological effects and exposure criteria for radiofrequency electromagnetic radiation, (2) Radiation protection in mammography, (3) Radiation exposure and potentially related injury, (4) Policy in regard to the international system of units, and (5) Radiation exposure control in a nuclear emergency. Twenty articles were abstracted separately for inclusion in the Energy Data Base and the International Nuclear Information System.

Not Available

1985-01-01

47

Greenhouse Gases  

NSDL National Science Digital Library

This is a lesson where learners engage in a radiating heat activity and an activity that measures temperature in models with and without greenhouse gases. Learners will draw conclusions about the effect of greenhouse gases on temperature and on human life and kinesthetically model the absorbing and re-radiation of heat. The lesson models scientific inquiry using the 5E instructional model and includes teacher notes, prerequisite concepts, common misconceptions, student journal and reading. This is lesson 3 in the Astro-Venture Atmospheric Science Training Unit. The purpose of the unit is to increase studentsâ awareness of and interest in astrobiology and the many career opportunities that utilize science, math and technology skills. The lessons are designed for educators to use in conjunction with the Astro-Venture multimedia modules.

48

Changes in partial pressures of respiratory gases during submerged voluntary breath hold across odontocetes: is body mass important?  

PubMed

Odontocetes have an exceptional range in body mass spanning 10(3) kg across species. Because, size influences oxygen utilization and carbon dioxide production rates in mammals, this lineage likely displays an extraordinary variation in oxygen store management compared to other marine mammal groups. To examine this, we measured changes in the partial pressures of respiratory gases ([Formula: see text], [Formula: see text]), pH, and lactate in the blood during voluntary, quiescent, submerged breath holds in Pacific white-sided dolphins (Lagenorhynchus obliquidens), bottlenose dolphins (Tursiops truncatus), and a killer whale (Orcinus orca) representing a mass range of 96-3,850 kg. These measurements provided an empirical determination of the effect of body size on the variability in blood biochemistry during breath hold and experimentally determined aerobic dive limits (ADL) within one taxonomic group (odontocetes). For the species in this study, maximum voluntary breath-hold duration was positively correlated with body mass, ranging from 3.5 min in white-sided dolphins to 13.3 min for the killer whale. Variation in breath-hold duration was associated with differences in the rate of change for [Formula: see text] throughout breath hold; [Formula: see text] decreased twice as fast for the two smaller species (-0.6 mmHg O(2) min(-1)) compared to the largest species (-0.3 mmHg O(2) min(-1)). In contrast, the rate of increase in [Formula: see text] during breath hold was similar across species. These results demonstrate that large body size in odontocetes facilitates increased aerobic breath-hold capacity as mediated by decreased mass-specific metabolic rates (rates of change in [Formula: see text] served as a proxy for oxygen utilization). Indeed the experimentally determined 5 min ADL for bottlenose dolphins was surpassed by the 13.3 min maximum breath hold of the killer whale, which did not end in a rise in lactate. Rather, breath hold ended voluntarily as respiratory gases and pH fell within a narrow range for both large and small species, likely providing cues for ventilation. PMID:21935721

Noren, S R; Williams, T M; Ramirez, K; Boehm, J; Glenn, M; Cornell, L

2012-02-01

49

Improving estimation of hourly, daily, and monthly solar radiation by importing global data sets  

Microsoft Academic Search

Surface solar radiation is an important parameter in hydrological models and crop yield models. This study developed a model to estimate solar radiation from sunshine duration. The model is more accurate and more general than traditional Ångström–Prescott models. It can explicitly account for radiative extinction processes in the atmosphere. Moreover, global data sets that describe the spatial and temporal distribution

Kun Yang; Toshio Koike; Baisheng Ye

2006-01-01

50

Shifting of infrared radiation using rotational raman resonances in diatomic molecular gases  

DOEpatents

A device for shifting the frequency of infrared radiation from a CO.sub.2 laser by stimulated Raman scattering in either H.sub.2 or D.sub.2. The device of the preferred embodiment comprises an H.sub.2 Raman laser having dichroic mirrors which are reflective for 16 .mu.m radiation and transmittive for 10 .mu.m, disposed at opposite ends of an interaction cell. The interaction cell contains a diatomic molecular gas, e.g., H.sub.2, D.sub.2, T.sub.2, HD, HT, DT and a capillary waveguide disposed within the cell. A liquid nitrogen jacket is provided around the capillary waveguide for the purpose of cooling. In another embodiment the input CO.sub.2 radiation is circularly polarized using a Fresnel rhomb .lambda./4 plate and applied to an interaction cell of much longer length for single pass operation.

Kurnit, Norman A. (Santa Fe, NM)

1980-01-01

51

Greenhouse Gases  

MedlinePLUS

... are greenhouse gases? Many chemical compounds present in Earth's atmosphere behave as 'greenhouse gases'. These are gases ... direct sunlight (relative shortwave energy) to reach the Earth's surface unimpeded. As the shortwave energy (that in ...

52

Manure Gases  

MedlinePLUS

... gases of most concern are ammonia and hydrogen sulfide. Other gases of concern include methane and carbon ... Since most of these gases in particular hydrogen sulfide are heavier-than-air, they tend to settle ...

53

Implantation of high concentration noble gases in cubic zirconia and silicon carbide: A contrasted radiation tolerance  

NASA Astrophysics Data System (ADS)

The modifications of the microstructure of yttria-stabilized cubic zirconia and silicon carbide single crystals implanted with high concentrations of noble gas ions and subsequently annealed at high temperature were characterized using RBS/C, XRD and TEM. It is found that the annealing behavior is strongly dependent on both the material and the implanted noble gases. Ar-implanted yttria-stabilized zirconia shows no significant microstructural modification upon annealing at 800 °C, e.g. dislocations are still present and the size of the Ar bubbles does not evolve. This is in strong contrast with previous observations on helium-implanted zirconia, where the formation of bubbles and elongated fractures were observed. In the case of SiC, thermal annealing at 1000 °C shows an enhanced damage recovery when He is implanted as compared to Ar implantation and the recrystallization of the matrix is accompanied with the release of noble gas atoms. This difference can be ascribed to different atomic radii, and thus mobility of implanted species.

Veli?a, Gihan; Debelle, Aurélien; Thomé, Lionel; Mylonas, Stamatis; Vincent, Laetitia; Boulle, Alexandre; Jagielski, Jacek; Pantelica, Dan

2014-08-01

54

A Hypothesis on Biological Protection from Space Radiation Through the Use of New Therapeutic Gases as Medical Counter Measures  

NASA Technical Reports Server (NTRS)

Exposure to astronauts could be a significant obstacle for long duration manned space exploration because of current uncertainties regarding the extent of biological effects. Furthermore, concepts for protective shielding also pose a technically challenging issue due to the nature of cosmic radiation and current mass and power constraints with modern exploration technology. As biological damage from exposure is associated with increased oxidative stress, it would be enabling to mitigate and/or prevent stress prior to the development of clinical symptoms and disease. This paper hypothesizes a "systems biology" approach in which a combination of chemical and biological mitigation techniques are used conjunctively. It proposes using new, therapeutic, medical gases as both chemical radioprotectors for radical scavenging and biological promoters for management of the body s response to exposure. From reviewing radiochemistry of water, biological effects of CO, H2, NO, and H2S gas, and mechanisms of radiation biology, it is concluded that this approach may have great therapeutic potential for exposure. Furthermore, it also appears to have potential for curtailing the pathogenesis of other diseases in which oxidative stress has been implicated including cardiovascular disease, cancer, chronic inflammatory disease, hypertension, ischemia/reperfusion injury, acute respiratory distress syndrome, Parkinson s and Alzheimer s disease, cataracts, and aging.

Schoenfeld, Michael P.; Ansari, Rafat R.; Nakao, Atsunori; Wink, David

2011-01-01

55

BRIEF COMMUNICATIONS: Radiation emitted by mixtures of rare gases with hydrogen excited by an electron beam  

Microsoft Academic Search

An experimental investigation was made of the radiation emitted by R-H2 mixtures (R = He, Kr, Ne, Ar, Xe)excitedby abeam E ~ 150 keV electrons with a current density j~40 A\\/cm2. When the ratio of the components was Ar:H2 approx 100:1 and the argon pressure was ~ 1-3 atm, a new wide band was discovered in the range 240-430 nm

F. V. Bunkin; V. I. Derzhiev; Gennadii A. Mesyats; V. S. Skakun; Viktor F. Tarasenko; V. A. Yurovskii; Sergei I. Yakovlenko

1984-01-01

56

Radiative Interaction Between Driver and Driven Gases in an Arc-Driven Shock Tube  

NASA Technical Reports Server (NTRS)

An electric-arc driven shock tube was operated with hydrogen as the driven gas and either hydrogen or helium as the driver gas. Electron density was measured behind the primary shock wave spectroscopically from the width of the Beta line of hydrogen. The measured electron density values were many times greater than the values calculated by the Rankine - Hugoniot relations. By accounting for the radiative transfer from the driver gas to the driven gas, the measured electron density values were numerically recreated.

Bogdanoff, David W.; Park, Chul

2001-01-01

57

Investigation of the radiation brightness of gases around a burning model moving at supersonic velocity  

NASA Astrophysics Data System (ADS)

Experimental results are presented on the ablation and shape change of burning models made of a pyrotechnic composition moving in air at supersonic velocity. A radiometer was used to measure the radiation brightness at a wavelength of 0.63 micron in the shock layer and wake of the burning models. The glow characteristics are determined as a function of the initial air pressure in the path of motion; and a theoretical model for the motion and ablation of burning bodies flying at supersonic velocity is developed which satisfactorily describes the experimental results. The present study is of interest in connection with the aerodynamic heating of vehicles flying at hypersonic velocity in planetary atmospheres.

Baulin, N. N.; Kuvalkin, D. G.; Piliugin, N. N.; Taganov, O. K.; Tikhomirov, S. G.

1987-01-01

58

Noble Gases  

NASA Astrophysics Data System (ADS)

The noble gases are the group of elements - helium, neon, argon, krypton, xenon - in the rightmost column of the periodic table of the elements, those which have "filled" outermost shells of electrons (two for helium, eight for the others). This configuration of electrons results in a neutral atom that has relatively low electron affinity and relatively high ionization energy. In consequence, in most natural circumstances these elements do not form chemical compounds, whence they are called "noble." Similarly, much more so than other elements in most circumstances, they partition strongly into a gas phase (as monatomic gas), so that they are called the "noble gases" (also, "inert gases"). (It should be noted, of course, that there is a sixth noble gas, radon, but all isotopes of radon are radioactive, with maximum half-life a few days, so that radon occurs in nature only because of recent production in the U-Th decay chains. The factors that govern the distribution of radon isotopes are thus quite different from those for the five gases cited. There are interesting stories about radon, but they are very different from those about the first five noble gases, and are thus outside the scope of this chapter.)In the nuclear fires in which the elements are forged, the creation and destruction of a given nuclear species depends on its nuclear properties, not on whether it will have a filled outermost shell when things cool off and nuclei begin to gather electrons. The numerology of nuclear physics is different from that of chemistry, so that in the cosmos at large there is nothing systematically special about the abundances of the noble gases as compared to other elements. We live in a very nonrepresentative part of the cosmos, however. As is discussed elsewhere in this volume, the outstanding generalization about the geo-/cosmochemistry of the terrestrial planets is that at some point thermodynamic conditions dictated phase separation of solids from gases, and that the Earth and the rest of the inner solar were made by collecting the solids, to the rather efficient exclusion of the gases. In this grand separation the noble gases, because they are noble, were partitioned strongly into the gas phase. The resultant generalization is that the noble gases are very scarce in the materials of the inner solar system, whence their common synonym "rare gases."This scarcity is probably the most important single feature to remember about noble-gas cosmochemistry. As illustration of the absolute quantities, for example, a meteorite that contains xenon at a concentration of order 10 -10 cm3STP g -1 (4×10-15 mol g-1) would be considered relatively rich in xenon. Yet this is only 0.6 ppt (part per trillion, fractional abundance 10-12) by mass. In most circumstances, an element would be considered efficiently excluded from some sample if its abundance, relative to cosmic proportions to some convenient reference element, were depleted by "several" orders of magnitude. But a noble gas would be considered to be present in quite high concentration if it were depleted by only four or five orders of magnitude (in the example above, 10-10 cm3STP g-1 of xenon corresponds to depletion by seven orders of magnitude), and one not uncommonly encounters noble-gas depletion of more than 10 orders of magnitude.The second most important feature to note about noble-gas cosmochemistry is that while a good deal of the attention given to noble gases really is about chemistry, traditionally a good deal of attention is also devoted to nuclear phenomena, much more so than for most other elements. This feature is a corollary of the first feature noted above, namely scarcity. A variety of nuclear transmutation processes - decay of natural radionuclides and energetic particle reactions - lead to the production of new nuclei that are often new elements. Most commonly, the quantity of new nuclei originating in nuclear transmutation is very small compared to the quantity already present in the sample in question,

Podosek, F. A.

2003-12-01

59

Atmospheric radiation  

SciTech Connect

Studies of atmospheric radiative processes are summarized for the period 1987-1990. Topics discussed include radiation modeling; clouds and radiation; radiative effects in dynamics and climate; radiation budget and aerosol effects; and gaseous absorption, particulate scattering and surface reflection. It is concluded that the key developments of the period are a defining of the radiative forcing to the climate system by trace gases and clouds, the recognition that cloud microphysics and morphology need to be incorporated not only into radiation models but also climate models, and the isolation of a few important unsolved theoretical problems in atmospheric radiation.

Harshvardhan, M.R. (USAF, Geophysics Laboratory, Hanscom AFB, MA (United States))

1991-01-01

60

Measurements of Ice Particles in Tropical Cirrus Anvils: Importance in Radiation Balance.  

National Technical Information Service (NTIS)

Cirrus is important in the radiation balance of the global atmosphere, both at solar and thermal infrared (IR) wavelengths. In particular cirrus produced by deep convection over the oceans in the tropics may be critical in controlling processes whereby en...

T. Foster W. P. Arnott J. Hallett R. Pueschel

1994-01-01

61

Important step in radiation carcinogenesis may be inactivation of cellular genes  

SciTech Connect

The loss of genetic material may result in a predisposition to malignant disease. The best studied example is retinoblastoma where deletion or transcriptional inactivation of a specific gene is associated with the development of the tumor. When hereditary retinoblastoma patients are treated with radiation, the incidence of osteosarcoma within the treatment field is extremely high compared to other cancer patients treated with radiotherapy. These data, together with cytogenetic and molecular data on the development of acute non-lymphocytic leukemia secondary to radiotherapy and chemotherapy treatment suggest that radiation-induced deletions of critical DNA sequences may be an important event in radiation carcinogenesis. Therefore, we propose that radiation-induced tumors may result from deletion of tissue specific regulatory genes. Base alterations caused by radiation in dominantly transforming oncogenes may also contribute to radiation carcinogenesis.62 references.

Weichselbaum, R.R.; Beckett, M.A.; Diamond, A.A.

1989-01-01

62

Identification of aerosol type over the Arabian Sea in the premonsoon season during the Integrated Campaign for Aerosols, Gases and Radiation Budget (ICARB)  

Microsoft Academic Search

A discrimination of the different aerosol types over the Arabian Sea (AS) during the Integrated Campaign for Aerosols, Gases and Radiation Budget (ICARB-06) is made using values of aerosol optical depth (AOD) at 500 nm (AOD500) and Ångström exponent (?) in the spectral band 340–1020 nm (?340–1020). For this purpose, appropriate thresholds for AOD500 and ?340–1020 are applied. It is

M. C. R. Kalapureddy; D. G. Kaskaoutis; P. Ernest Raj; P. C. S. Devara; H. D. Kambezidis; P. G. Kosmopoulos; P. T. Nastos

2009-01-01

63

Radiatively important parameters best estimate (RIPBE) value-added product (VAP)  

SciTech Connect

Currently, to calculate radiative heating rate profiles for the Broadband Heating Rate Profile (BBHRP) product, radiatively important parameters (water vapor, ozone, surface albedo, aerosol properties, and cloud properties) from multiple VAPs and datastreams are combined into input text files that are then used to run the RRTM radiative transfer codes. These input parameters have different temporal and spatial scales and are difficult to extract from the text files to be used for other purposes such as running other radiative transfer codes, analyzing results, or error tracking. The purpose of the Radiatively Important Parameters Best Estimate (RIPBE) VAP is to improve this process by creating a clearly identified set of inputs for BBHRP (and other radiation codes) on a uniform vertical and temporal grid. This process will decouple the input/output portion of the BBHRP from the core physics (the RRTM radiative transfer model) and will add error tracking and version information to the input data set. Critical parameters (which must exist for the radiation code to be run) will be designated; for other parameters, climatological or fixed values will be used when the preferred values are missing. This should increase the number of cases for which radiative transfer calculations can be run. In all cases, flags will clearly identify the source for each parameter. RIPBE will serve multiple functions: (1) it will provide a clearly identifiable set of inputs for BBHRP, (2) it will facilitate the use of BBHRP as a retrieval and radiation code development testbed by providing a vehicle for easily extracting and swapping input parameters needed to conduct radiative transfer calculations, and (3) it will be a complement to the Climate Modeling Best Estimate (CMBE) VAP and will provide a significantly expanded set of parameters for model evaluation in a showcase data set form. At the ASR meeting, we will present examples and evaluation of the initial RIPBE dataset at SGP.

Shippert,T.; Jensen,M.; McFarlane, S.; Mather, J.; Flynn, C.; Mlawer, E.; Delamere, J.; Oreopoulos, L.; Turner, D.; Xie, S.

2010-03-15

64

Trends in source gases  

NASA Technical Reports Server (NTRS)

Source gases are defined as those gases that, by their breakdown, introduce into the stratosphere halogen, hydrogen, and nitrogen compounds that are important in stratospheric ozone destruction. Given here is an update of the existing concentration time series for chlorocarbons, nitrous oxide, and methane. Also reviewed is information on halogen containing species and the use of these data for establishing trends. Also reviewed is evidence on trends in trace gases that influence tropospheric chemistry and thus the tropospheric lifetimes of source gases, such as carbon dioxide, carbon monoxide, or nitrogen oxides. Much of the information is given in tabular form.

Ehhalt, D. H.; Fraser, P. J.; Albritton, D.; Cicerone, R. J.; Khalil, M. A. K.; Legrand, M.; Makide, Y.; Rowland, F. S.; Steele, L. P.; Zander, R.

1989-01-01

65

Radiatively Important Parameters Best Estimate (RIPBE): An ARM Value-Added Product  

SciTech Connect

The Radiatively Important Parameters Best Estimate (RIPBE) VAP was developed to create a complete set of clearly identified set of parameters on a uniform vertical and temporal grid to use as input to a radiative transfer model. One of the main drivers for RIPBE was as input to the Broadband Heating Rate Profile (BBHRP) VAP, but we also envision using RIPBE files for user-run radiative transfer codes, as part of cloud/aerosol retrieval testbeds, and as input to averaged datastreams for model evaluation.

McFarlane, S; Shippert, T; Mather, J

2011-06-30

66

From Anti-greenhouse Effect of Solar Absorbers to Cooling Effect of Greenhouse Gases: A 1-D Radiative Convective Model Study  

NASA Astrophysics Data System (ADS)

The haze layer in Titan's upper atmosphere absorbs 90% of the solar radiation, but is inefficient for trapping infrared radiation generated by the surface. Its existence partially compensates for the greenhouse warming and keeps the surface approximately 9°C cooler than would otherwise be expected from the greenhouse effect alone. This is the so called anti-greenhouse effect (McKay et al., 1991). This effect can be used to alleviate the warming caused by the increasing level of greenhouse gases in the Earth's atmosphere. A one-dimensional radiative convective model (Kasting et al., 2009 and references listed there) is used to investigate the anti-greenhouse effect in the Earth atmosphere. Increasing of solar absorbers, e.g. aerosols and ozone, in the stratosphere reduces the surface solar flux and cool the surface. However, the absorption of the solar flux also increases the temperature in the upper atmosphere, while reduces the temperature at the surface. Thus, the temperature profile of the atmosphere changes and the regions with positive vertical temperature gradient are expanded. According to Shia (2010) the radiative forcing of greenhouse gases is directly related to the vertical temperature gradient. Under the new temperature profile increases of greenhouse gases should have less warming effect. When the solar absorbers keep increasing, eventually most of the atmosphere has positive temperature gradient and increasing greenhouse gases would cool the surface (Shia, 2011). The doubling CO2 scenario in the Earth atmosphere is simulated for different levels of solar absorbers using the 1-D RC model. The model results show that if the solar absorber increases to a certain level that less than 50% solar flux reaching the surface, doubling CO2 cools the surface by about 2 C. This means if the snowball Earth is generated by solar absorbers in the stratosphere, increasing greenhouse gases would make it freeze even more (Shia, 2011). References: Kasting, J. et al. 2009, http://vpl.astro.washington.edu/sci/AntiModels/models09.html McKay, C.P. et al. 1991, Titan: Greenhouse and Anti-greenhouse Effects on Titan. Science 253 (5024), 1118-21 Shia, R. 2011, Climate Effect of Greenhouse Gas: Warming or Cooling is Determined by Temperature Gradient, American Geophysical Union, Fall Meeting 2012, abstract #A51A-0274 Shia, R. 2010, Mechanism of Radiative Forcing of Greenhouse Gas and its Implication to the Global Warming, American Geophysical Union, Fall Meeting 2010, abstract #A11J-02

Shia, R.

2012-12-01

67

The importance of the diurnal and annual cycle of air traffic for contrail radiative forcing.  

PubMed

Air traffic condensation trails, or contrails, are believed to have a net atmospheric warming effect, although one that is currently small compared to that induced by other sources of human emissions. However, the comparably large growth rate of air traffic requires an improved understanding of the resulting impact of aircraft radiative forcing on climate. Contrails have an effect on the Earth's energy balance similar to that of high thin ice clouds. Their trapping of outgoing longwave radiation emitted by the Earth and atmosphere (positive radiative forcing) is partly compensated by their reflection of incoming solar radiation (negative radiative forcing). On average, the longwave effect dominates and the net contrail radiative forcing is believed to be positive. Over daily and annual timescales, varying levels of air traffic, meteorological conditions, and solar insolation influence the net forcing effect of contrails. Here we determine the factors most important for contrail climate forcing using a sophisticated radiative transfer model for a site in southeast England, located in the entrance to the North Atlantic flight corridor. We find that night-time flights during winter (December to February) are responsible for most of the contrail radiative forcing. Night flights account for only 25 per cent of daily air traffic, but contribute 60 to 80 per cent of the contrail forcing. Further, winter flights account for only 22 per cent of annual air traffic, but contribute half of the annual mean forcing. These results suggest that flight rescheduling could help to minimize the climate impact of aviation. PMID:16778887

Stuber, Nicola; Forster, Piers; Rädel, Gaby; Shine, Keith

2006-06-15

68

Using Radiation Risk Models in Cancer Screening Simulations: Important Assumptions and Effects on Outcome Projections  

PubMed Central

Purpose: To evaluate the effect of incorporating radiation risk into microsimulation (first-order Monte Carlo) models for breast and lung cancer screening to illustrate effects of including radiation risk on patient outcome projections. Materials and Methods: All data used in this study were derived from publicly available or deidentified human subject data. Institutional review board approval was not required. The challenges of incorporating radiation risk into simulation models are illustrated with two cancer screening models (Breast Cancer Model and Lung Cancer Policy Model) adapted to include radiation exposure effects from mammography and chest computed tomography (CT), respectively. The primary outcome projected by the breast model was life expectancy (LE) for BRCA1 mutation carriers. Digital mammographic screening beginning at ages 25, 30, 35, and 40 years was evaluated in the context of screenings with false-positive results and radiation exposure effects. The primary outcome of the lung model was lung cancer–specific mortality reduction due to annual screening, comparing two diagnostic CT protocols for lung nodule evaluation. The Metropolis-Hastings algorithm was used to estimate the mean values of the results with 95% uncertainty intervals (UIs). Results: Without radiation exposure effects, the breast model indicated that annual digital mammography starting at age 25 years maximized LE (72.03 years; 95% UI: 72.01 years, 72.05 years) and had the highest number of screenings with false-positive results (2.0 per woman). When radiation effects were included, annual digital mammography beginning at age 30 years maximized LE (71.90 years; 95% UI: 71.87 years, 71.94 years) with a lower number of screenings with false-positive results (1.4 per woman). For annual chest CT screening of 50-year-old females with no follow-up for nodules smaller than 4 mm in diameter, the lung model predicted lung cancer–specific mortality reduction of 21.50% (95% UI: 20.90%, 22.10%) without radiation risk and 17.75% (95% UI: 16.97%, 18.41%) with radiation risk. Conclusion: Because including radiation exposure risk can influence long-term projections from simulation models, it is important to include these risks when conducting modeling-based assessments of diagnostic imaging. © RSNA, 2012 Supplemental material: http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.11110352/-/DC1

Lee, Janie M.; McMahon, Pamela M.; Lowry, Kathryn P.; Omer, Zehra B.; Eisenberg, Jonathan D.; Pandharipande, Pari V.; Gazelle, G. Scott

2012-01-01

69

Greenhouse Gases  

MedlinePLUS

... were not for naturally occurring greenhouse gases, the Earth would be too cold to support life as ... the greenhouse effect, the average temperature of the Earth would be about -2°F rather than the ...

70

Measurement of Selected Organic Trace Gases During TRACE-P.  

National Technical Information Service (NTIS)

Major goals of the TRACE-P mission were: 1) to investigate the chemical composition of radiatively important gases, aerosols, and their precursors in the Asian outflow over the western Pacific, and 2) to describe and understand the chemical evolution of t...

E. Atlas

2004-01-01

71

Parameterization of the absorption of the H2O continuum, CO2, O2, and other trace gases in the Fu-Liou solar radiation program  

NASA Astrophysics Data System (ADS)

The absorption properties of the water vapor continuum and a number of weak bands for H2O, O2, CO2, CO, N2O, CH4, and O3 in the solar spectrum are incorporated into the Fu-Liou radiation parameterization program by using the correlated k-distribution method (CKD) for the sorting of absorption lines. The overlap absorption of the H2O lines and the H2O continuum (2500 14500 cm-1) are treated by taking the two gases as a single-mixture gas in transmittance calculations. Furthermore, in order to optimize the computation efforts, CO2 and CH4 in the spectral region 2850 5250 cm-1 are taken as a new single-mixture gas as well. For overlap involving other absorption lines in the Fu-Liou spectral bands, the authors adopt the multiplication rule for transmittance computations under which the absorption spectra for two gases are assumed to be uncorrelated. Compared to the line-by-line (LBL) computation, it is shown that the errors in fluxes introduced by these two approaches within the context of the CKD method are small and less than 0.48% for the H2O line and continuum in the 2500 14500 cm-1solar spectral region, ˜1% for H2O (line)+H2O (continuum)+CO2+CH4 in the spectral region 2850 5250 cm-1,and ˜1.5% for H2O (line)+H2O (continuum)+O2 in the 7700 14500 cm-1 spectral region. Analysis also demonstrates that the multiplication rule over a spectral interval as wide as 6800 cm-1 can produce acceptable errors with a maximum percentage value of about 2% in reference to the LBL calculation. Addition of the preceding gases increases the absorption of solar radiation under all sky conditions. For clear sky, the increase in instantaneous solar absorption is about 9% 13% (˜12 W m-2) among which the H2O continuum produces the largest increase, while the contributions from O2 and CO2 rank second and third, respectively. In cloudy sky, the addition of absorption amounts to about 6 9 W m-2. The new, improved program with the incorporation of the preceding gases produces a smaller solar absorption in clouds due to the reduced solar flux reaching the cloud top.

Zhang, Feng; Zeng, Qingcun; Gu, Y.; Liou, K. N.

2005-07-01

72

Atmospheric gases  

NSDL National Science Digital Library

Which gases make up the atmosphere? This activity page, part of an interactive laboratory series for grades 8-12, introduces students to the gaseous components of the atmosphere. Students explore the main gases of the atmosphere using a pop-up pie chart. Descriptions of the gases and their percentages in the atmosphere are provided. Students read about water vapor in the atmosphere, and an animation shows a simplified process of precipitation. A pop-up window explains the effects of dust on the atmosphere, and a photograph shows how large amounts of dust in the atmosphere create the reds and oranges displayed in sunsets. Finally, ozone is introduced to students as a necessary component of human life on Earth. Copyright 2005 Eisenhower National Clearinghouse

University of Utah. Astrophysics Science Project Integrating Research and Education (ASPIRE)

2003-01-01

73

On the cause of the relative greenhouse strength of gases such as the halocarbons  

Microsoft Academic Search

This note examines some of the factors important in determining the large radiative impact, relative to carbon dioxide, of increased concentrations of gases in the optically thin limit (such as the halocarbons at their present day concentrations). A narrow-band radiative transfer model is used to show that an absorber with the same integrated band strength as CFC-12, but with almost

Keith P. Shine

1991-01-01

74

Important Role of Autophagy in Endothelial Cell Response to Ionizing Radiation  

PubMed Central

Objectives Vasculature damage is an important contributor to the side-effects of radiotherapy. The aim of this study is to provide insights into the radiobiology of the autophagic response of endothelial cells. Methods and Materials Human umbilical vascular endothelial cells (HUVEC) were exposed to 2 Gy of ionizing radiation (IR) and studied using confocal microscopy and western blot analysis, at 4 and 8 days post-irradiation. The role of autophagy flux in HUVEC radio-sensitivity was also examined. Results IR-induced accumulation of LC3A+, LC3B+ and p62 cytoplasmic vacuoles, while in double immunostaining with lysosomal markers (LAMP2a and CathepsinD) repression of the autophagolysosomal flux was evident. Autophagy-related proteins (ATF4, HIF1?., HIF2?, Beclin1) were, however, induced excluding an eventual repressive effect of radiation on autophagy initiating protein expression. Exposure of HUVEC to SMER28, an mTOR-independent inducer of autophagy, enhanced proLC3 and LC3A, B-I protein expression and accelerated the autophagic flux. Pre-treatment of HUVEC with SMER28 protected against the blockage of autophagic flux induced by IR and conferred radio-resistance. Suppression of LC3A/LC3B proteins with siRNAs resulted in radio-sensitization. Conclusions The current data provide a rationale for the development of novel radioprotection policies targeting the autophagic pathway.

Kalamida, Dimitra; Karagounis, Ilias V.; Giatromanolaki, Alexandra; Koukourakis, Michael I.

2014-01-01

75

Determine Important Nuclear Fragmentation Processes for Space Radiation Protection in Human Space Explorations  

NASA Technical Reports Server (NTRS)

Space radiation from cosmic ray particles is one of the main challenges for long-term human space explorations such as a permanent moon base or a trip to Mars. Material shielding may provide significant radiation protection to astronauts, and models have been developed in order to evaluate the effectiveness of different shielding materials and to predict radiation environment inside the spacecraft. In this study we determine the nuclear fragmentation cross sections which will most affect the radiation risk behind typical radiation shielding materials. These cross sections thus need more theoretical studies and accurate experimental measurements in order for us to more precisely predict the radiation risk in human space exploration.

Lin, Zi-Wei

2004-01-01

76

Determine Important Nuclear Fragmentation Processes for Space Radiation Protection in Human Space Explorations  

NASA Technical Reports Server (NTRS)

Space radiation from cosmic ray particles is one of the main challenges for long-term human space explorations such as a permanent moon base or a trip to Mars. Material shielding may provide significant radiation protection to astronauts, and models have been developed in order to evaluate the effectiveness of different shielding materials and to predict radiation environment inside the spacecraft. In this study we determine the nuclear fragmentation cross sections which will most effect the radiation risk behind typical radiation shielding materials. These cross sections thus need more theoretical studies and accurate experimental measurements in order for us to more precisely predict the radiation risk in human space explorations.

Lin, Zi-wei

2004-01-01

77

A study of ambient upstream material properties using perpendicular laser driven radiative blast waves in atomic cluster gases  

NASA Astrophysics Data System (ADS)

We report on the characterisation of the upstream medium ahead of a radiative cylindrical blast wave launched in an argon cluster gas with a 1 J, 1 ps, 1054 nm Nd:Glass laser system. By launching two perpendicular blast waves and introducing a time delay between the heating beams it is possible to determine the extent of the cluster medium by observing the high energy absorption region associated with clusters, as apposed to the low energy deposition in monatomic gas. It was found that argon ions launched from the initial laser driven cluster ionisation created a ballistic ion wave which sweeps out ahead of the hydrodynamic blast wave at an initial velocity of 1000 kms -1. This ballistic wave disassembles the clusters ahead of the blast wave into a neutral gas medium before the arrival of a radiative precursor. This observation gives us confidence that the dynamics of a radiative blast wave in cluster based experiments is determined primarily by the properties of an upstream atomic gas, and is not significantly influenced by cluster affects on energy transport or other material properties.

Olsson Robbie, S. I.; Doyle, H. W.; Symes, D. R.; Smith, R. A.

2012-03-01

78

Transport fluxes and emission of greenhouse gases of the Middle Niger River (west Africa): disproprotionate importance of the recent red floods in the Niamey region  

NASA Astrophysics Data System (ADS)

The Niger River is Africa's third longest river and drains an area of ~2,120,000 km². It encompasses six hydrographic regions and crosses almost all possible ecosystem zones in West Africa. Since few decades, the Middle Niger River presents a two flood hydrograph, the local flood, or red flood, occurring during the rainy season being the more pronounced one. Here, we report initial results of a monitoring campaign whereby 2-weekly samples were collected at Niamey (Niger) [2.01°E 13.57°N] between April 2011 and March 2013 for a suite of physico-chemical and biogeochemical characteristics, including total suspended matter (TSM) concentrations, concentration and stable isotope composition of particulate organic carbon (POC and ?13C-POC) and particulate nitrogen (PN and ?15N-PN), chromophoric dissolved organic matter (CDOM), dissolved organic carbon (DOC and ?13C-DOC), dissolved inorganic carbon (DIC and ?13C-DIC), concentration of greenhouse gases (GHGs) (CO2, CH4 and N2O), as well as major elements, total alkalinity, and oxygen isotope signatures of water (?18O-H2O). This dataset allows us to construct seasonal budgets for particulate and dissolved carbon fluxes, nutrient exports, as well as a first seasonally resolved characterisation of the GHGs emitted to the atmosphere by the Middle Niger River. The red flood, concentrated on 2 months (August-September), contributed to more than 80% of the annual transport fluxes of TSM and POC and to approximately 30% of the annual transport fluxes of DIC and DOC.

Darchambeau, François; Bouillon, Steven; Alhou, Bassirou; Lambert, Thibault; Borges, Alberto V.

2014-05-01

79

Greenhouse gases: What is their role in climate change  

Microsoft Academic Search

This paper summarizes information relevant to understanding the role of greenhouse gases in the atmosphere. It examines the nature of the greenhouse effect, the Earth's radiation budget, the concentrations of these gases in the atmosphere, how these concentrations have been changing, natural processes which regulate these concentrations of greenhouse gases, residence times of these gases in the atmosphere, and the

J. A. Edmonds; W. U. Chandler; D. Wuebbles

1990-01-01

80

Topography-adjusted solar radiation indices and their importance in hydrology  

Microsoft Academic Search

Solar radiation, direct and diffuse, is affected by surface characteristics, such as slope, aspect, altitude and shading. The paper examines the effects of topography on radiation, at multiple spatiotemporal scales, using suitable geometric methods for the direct and diffuse components. Two indices are introduced for comparing the direct radiation received by areas at the same and different latitudes. To investigate

Nikos Mamassis; Andreas Efstratiadis; Ilektra-Georgia Apostolidou

2012-01-01

81

Global tropospheric chemistry models for radiatively important trace species: Design and research recommendations  

SciTech Connect

Changes in the Earth`s climate could significantly affect regional and global concentrations of trace species that are criteria pollutants regulated by the US Environmental Protection Agency (EPA). The policy community also needs to know how changes in global natural and anthropogenic emissions of greenhouse gases, particulate aerosols, and aerosol precursors will affect the distribution and concentration of these pollutants. This report maps out one path for obtaining this information.

Barchet, W.R.; Brothers, A.J.; Berkowitz, C.M.; Easter, R.C.; Ghan, S.J.; Saylor, R.D.

1993-12-01

82

Physical and Optical/Radiative Characteristics of Aerosol and Cloud Particles in Tropical Cirrus: Importance in Radiation Balance  

NASA Technical Reports Server (NTRS)

Whether cirrus clouds heat or cool the Earth-atmosphere system depends on the relative importance of the cloud shortwave albedo effect and the cloud thermal greenhouse effect. Both are determined by the distribution of ice condensate with cloud particle size. The microphysics instrument package flown aboard the NASA DC-8 in TOGA/COARE included an ice crystal replicator, a 2D Greyscale Cloud Particle Probe and a Forward Scattering Spectrometer Aerosol Probe. In combination, the electro-optical instruments permitted particle size measurements between 0.5 micrometer and 2.6 millimeter diameter. Ice crystal replicas were used to validate signals from the electrooptical instruments. Both optical and scanning electron microscopy were utilized to analyze aerosol and ice particle replicas between 0.1 micrometer and several 100 micrometer diameter. In first approximation, the combined aerosol-cloud particle spectrum in several clouds followed a power law N alpha D(sup -2.5). Thus, large cloud particles carried most of the condensate mass, while small cloud and aerosol particles determined the surface area. The mechanism of formation of small particles is growth of (hygroscopic, possibly ocean-derived) aerosol particles along the Kohler curves. The concentration of small particles is higher and less variable in space and time, and their tropospheric residence time is longer, than those of large cloud particles because of lower sedimentation velocities. Small particles shift effective cloud particle radii to sizes much smaller than the mean diameter of the cloud particles. This causes an increase in shortwave reflectivity and IR emissivity, and a decrease in transmissivity. Occasionally, the cloud reflectivity increased with altitude (decreasing temperature) stronger than did cloud emissivity, yielding enhanced radiative cooling at higher altitudes. Thus, cirrus produced by deep convection in the tropics may be critical in controlling processes whereby energy from warm tropical oceans is injected to different levels in the atmosphere to subsequently influence not only tropical but mid-latitude climate.

Pueschel, R. F.; Howard, S. D.; Foster, T. C.; Hallett, J.; Arnott, W. P.; Condon, Estelle P. (Technical Monitor)

1996-01-01

83

Heat and mass transfer in gases due to pressure and temperature gradients in a laser radiation field  

NASA Astrophysics Data System (ADS)

Heat and mass transfer in a one-component gas through a capillary in the field of resonant laser radiation in the presence of pressure and temperature gradients are considered. On the basis of the Boltzmann type kinetic equations in the linear approximation the expression for entropy production is obtained. Kinetic coefficients satisfy the Onsager reciprocity relations at all Knudsen numbers and for any nature of the interaction of gas atoms with the surface of the capillary. The pressure and temperature gradients established in the insulated system in a laser field are defined in a nearly free molecular regime.

Chermyaninov, I. V.; Chernyak, V. G.

2012-11-01

84

Two-dimensional Radiative Magnetohydrodynamic Simulations of the Importance of Partial Ionization in the Chromosphere  

NASA Astrophysics Data System (ADS)

The bulk of the solar chromosphere is weakly ionized and interactions between ionized particles and neutral particles likely have significant consequences for the thermodynamics of the chromospheric plasma. We investigate the importance of introducing neutral particles into the MHD equations using numerical 2.5D radiative MHD simulations obtained with the Bifrost code. The models span the solar atmosphere from the upper layers of the convection zone to the low corona, and solve the full MHD equations with non-gray and non-LTE radiative transfer, and thermal conduction along the magnetic field. The effects of partial ionization are implemented using the generalized Ohm's law, i.e., we consider the effects of the Hall term and ambipolar diffusion in the induction equation. The approximations required in going from three fluids to the generalized Ohm's law are tested in our simulations. The Ohmic diffusion, Hall term, and ambipolar diffusion show strong variations in the chromosphere. These strong variations of the various magnetic diffusivities are absent or significantly underestimated when, as has been common for these types of studies, using the semi-empirical VAL-C model as a basis for estimates. In addition, we find that differences in estimating the magnitude of ambipolar diffusion arise depending on which method is used to calculate the ion-neutral collision frequency. These differences cause uncertainties in the different magnetic diffusivity terms. In the chromosphere, we find that the ambipolar diffusion is of the same order of magnitude or even larger than the numerical diffusion used to stabilize our code. As a consequence, ambipolar diffusion produces a strong impact on the modeled atmosphere. Perhaps more importantly, it suggests that at least in the chromospheric domain, self-consistent simulations of the solar atmosphere driven by magnetoconvection can accurately describe the impact of the dominant form of resistivity, i.e., ambipolar diffusion. This suggests that such simulations may be more realistic in their approach to the lower solar atmosphere (which directly drives the coronal volume) than previously assumed.

Martínez-Sykora, Juan; De Pontieu, Bart; Hansteen, Viggo

2012-07-01

85

Study of defects, radiation damage and implanted gases in solids by field-ion and atom-probe microscopy  

SciTech Connect

The ability of the field-ion microscope to image individual atoms has been applied, at Cornell University, to the study of fundamental properties of point defects in irradiated or quenched metals. The capability of the atom probe field-ion microscope to determine the chemistry - that is, the mass-to-charge ratio - of a single ion has been used to investigate the behavior of different implanted species in metals. A brief review is presented of: (1) the basic physical principles of the field-ion and atom-probe microscopes; (2) the many applications of these instruments to the study of defects and radiation damage in solids; and (3) the application of the atom-probe field-ion microscope to the study of the behavior of implanted /sup 3/He and /sup 4/He atoms in tungsten. The paper is heavily referenced so that the reader can pursue his specific research interests in detail.

Seidman, D.N.; Amano, J.; Wagner, A.

1980-10-01

86

On the generation of supershort avalanche electron beams and x radiation during nanosecond discharges in dense gases (results and discussion)  

NASA Astrophysics Data System (ADS)

Results of investigations of the generation of subnanosecond runaway electron beams and x radiation in gas diodes at elevated pressures are presented. The energy distributions of runaway electron beams generated in air at atmospheric pressure and the amplitude and duration of beam current pulses downstream of the foil have been measured, and also the mechanism of generation of a runaway electron beam has been analyzed. To record the beam current pulses, a collector which provided ˜50-ps time resolution and a Tektronix TDS6604 real-time oscilloscope were used in the experiment. It has been shown that the new experimental data and model predictions confirm in the main the results earlier obtained at the Institute of High Current Electronics of the Russian Academy of Sciences Siberian Division. Evidence is cited that the key statements of L. P. Babich are erroneous.

Tarasenko, V. F.; Rybka, D. B.; Baksht, E. H.; Kostyrya, I. D.; Lomaev, M. I.

2007-09-01

87

Present state of knowledge of the upper atmosphere: An assessment report; processes that control ozone and other climatically important trace gases  

NASA Technical Reports Server (NTRS)

The state of knowledge of the upper atmosphere was assessed as of January 1986. The physical, chemical, and radiative processes which control the spatial and temporal distribution of ozone in the atmosphere; the predicted magnitude of ozone perturbations and climate changes for a variety of trace gas scenarios; and the ozone and temperature data used to detect the presence or absence of a long term trend were discussed. This assessment report was written by a small group of NASA scientists, was peer reviewed, and is based primarily on the comprehensive international assessment document entitled Atmospheric Ozone 1985: Assessment of Our Understanding of the Processes Controlling Its Present Distribution and Change, to be published as the World Meteorological Organization Global Ozone Research and Monitoring Project Report No. 16.

Watson, R. T.; Geller, M. A.; Stolarski, R. S.; Hampson, R. F.

1986-01-01

88

Climate-chemical interactions and effects of changing atmospheric trace gases  

Microsoft Academic Search

The problem concerning the greenhouse effects of human activities has broadened in scope from the CO2-climate problem to the trace gas-climate problem. The climate effects of non-CO2 trace gases are strongly governed by interactions between chemistry, radiation, and dynamics. We discuss in detail the nature of the trace gas radiative heating and describe the importance of radiative-chemical interactions within the

V. Ramanathan; L. Callis; R. Cess; J. Hansen; I. Isaksen; W. Kuhn; A. Lacis; F. Luther; J. Mahlman; R. Reck; M. Schlesinger

1987-01-01

89

Greenhouse gases: What is their role in climate change.  

National Technical Information Service (NTIS)

This paper summarizes information relevant to understanding the role of greenhouse gases in the atmosphere. It examines the nature of the greenhouse effect, the Earth's radiation budget, the concentrations of these gases in the atmosphere, how these conce...

D. Wuebbles J. A. Edmonds W. U. Chandler

1990-01-01

90

Importance of ATM Mutations and Polymorphisms in Breast Cancer and Radiation Sensitivity.  

National Technical Information Service (NTIS)

The primary objective of my 4-year career development award is to determine whether ATM heterozygosity is a significant contributor to both breast cancer risk and normal tissue injury resulting from radiation treatments of breast cancer. During the past y...

T. A. Buchholz

2000-01-01

91

Accurate Calculations of Global and Local Radiative Forcing due to Tropospheric Ozone and Nitrogen Dioxide  

Microsoft Academic Search

Since the launch of the A-train constellation of satellites in an afternoon polar orbit, much has been learned about the global distributions of the radiatively active tropospheric gases ozone and nitrogen dioxide. Both gases absorb radiation in the shortwave. In addition, tropospheric ozone is an important greenhouse gas. From A-train observations, we have also made great progress in understanding how

A. Vasilkov; J. Joiner; J. Gleason; M. Schoerberl; S. Platnick; L. Oreopoulos; P. Veefkind; E. Celarier; N. Livesey

2008-01-01

92

Importance of representing optical depth variability for estimates of global line-shaped contrail radiative forcing  

PubMed Central

Estimates of the global radiative forcing by line-shaped contrails differ mainly due to the large uncertainty in contrail optical depth. Most contrails are optically thin so that their radiative forcing is roughly proportional to their optical depth and increases with contrail coverage. In recent assessments, the best estimate of mean contrail radiative forcing was significantly reduced, because global climate model simulations pointed at lower optical depth values than earlier studies. We revise these estimates by comparing the probability distribution of contrail optical depth diagnosed with a climate model with the distribution derived from a microphysical, cloud-scale model constrained by satellite observations over the United States. By assuming that the optical depth distribution from the cloud model is more realistic than that from the climate model, and by taking the difference between the observed and simulated optical depth over the United States as globally representative, we quantify uncertainties in the climate model’s diagnostic contrail parameterization. Revising the climate model results accordingly increases the global mean radiative forcing estimate for line-shaped contrails by a factor of 3.3, from 3.5 mW/m2 to 11.6 mW/m2 for the year 1992. Furthermore, the satellite observations and the cloud model point at higher global mean optical depth of detectable contrails than often assumed in radiative transfer (off-line) studies. Therefore, we correct estimates of contrail radiative forcing from off-line studies as well. We suggest that the global net radiative forcing of line-shaped persistent contrails is in the range 8–20 mW/m2 for the air traffic in the year 2000.

Karcher, Bernd; Burkhardt, Ulrike; Ponater, Michael; Fromming, Christine

2010-01-01

93

Importance of representing optical depth variability for estimates of global line-shaped contrail radiative forcing.  

PubMed

Estimates of the global radiative forcing by line-shaped contrails differ mainly due to the large uncertainty in contrail optical depth. Most contrails are optically thin so that their radiative forcing is roughly proportional to their optical depth and increases with contrail coverage. In recent assessments, the best estimate of mean contrail radiative forcing was significantly reduced, because global climate model simulations pointed at lower optical depth values than earlier studies. We revise these estimates by comparing the probability distribution of contrail optical depth diagnosed with a climate model with the distribution derived from a microphysical, cloud-scale model constrained by satellite observations over the United States. By assuming that the optical depth distribution from the cloud model is more realistic than that from the climate model, and by taking the difference between the observed and simulated optical depth over the United States as globally representative, we quantify uncertainties in the climate model's diagnostic contrail parameterization. Revising the climate model results accordingly increases the global mean radiative forcing estimate for line-shaped contrails by a factor of 3.3, from 3.5 mW/m(2) to 11.6 mW/m(2) for the year 1992. Furthermore, the satellite observations and the cloud model point at higher global mean optical depth of detectable contrails than often assumed in radiative transfer (off-line) studies. Therefore, we correct estimates of contrail radiative forcing from off-line studies as well. We suggest that the global net radiative forcing of line-shaped persistent contrails is in the range 8-20 mW/m(2) for the air traffic in the year 2000. PMID:20974909

Kärcher, Bernd; Burkhardt, Ulrike; Ponater, Michael; Frömming, Christine

2010-11-01

94

Quantum Gases:. Setting the Scene  

NASA Astrophysics Data System (ADS)

We give a brief historical overview of the physical realisations of quantum degeneracy and Bose-Einstein condensation observed to date, with the aim of showing why quantum gases is a key rapidly evolving interdisciplinary field of physics. We motivate the need for developing more advanced theories to understand all the features observed in ultracold gases, and present some of the unresolved issues where the theories discussed in this book can play an important role.

Proukakis, Nick P.; Burnett, Keith

2013-02-01

95

Identification of aerosol type over the Arabian Sea in the premonsoon season during the Integrated Campaign for Aerosols, Gases and Radiation Budget (ICARB)  

NASA Astrophysics Data System (ADS)

A discrimination of the different aerosol types over the Arabian Sea (AS) during the Integrated Campaign for Aerosols, Gases and Radiation Budget (ICARB-06) is made using values of aerosol optical depth (AOD) at 500 nm (AOD500) and Ångström exponent (?) in the spectral band 340-1020 nm (?340-1020). For this purpose, appropriate thresholds for AOD500 and ?340-1020 are applied. It is shown that a single aerosol type in a given location over the AS can exist only under specific conditions while the presence of mixed aerosols is the usual situation. Analysis indicates that the dominant aerosol types change significantly in the different regions (coastal, middle, and far) of AS. Thus the urban/industrial aerosols are mainly observed in coastal AS, the desert dust particles occur in the middle and northern AS, while clear maritime conditions mainly occur in far AS. Spectral AOD and Ångström exponent data were analyzed to obtain information about the adequacy of the simple use of the Ångström exponent and spectral variation of ? for characterizing the aerosols. Using the least squares method, ? is calculated in the spectral interval 340-1020 nm along with the coefficients a1 and a2 of the second-order polynomial fit to the plotted logarithm of AOD versus the logarithm of wavelength. The results show that the spectral curvature can effectively be used as a tool for their discrimination, since the fine mode aerosols exhibit negative curvature, while the coarse mode particles exhibit positive curvature. The correlation between the coefficients a1 and a2 with the Ångström exponent, and the atmospheric turbidity, is further investigated.

Kalapureddy, M. C. R.; Kaskaoutis, D. G.; Ernest Raj, P.; Devara, P. C. S.; Kambezidis, H. D.; Kosmopoulos, P. G.; Nastos, P. T.

2009-09-01

96

Agricultural ecosystem effects on trace gases and global climate change  

SciTech Connect

Global climate change is an issue that has been thrust to the forefront of scientific, political, and general community interest. In the span of this human generation, the earth's climate is expected to change more rapidly than it has over any comparable period of recorded history. Some of the changes will result from natural processes, beyond human control, but much of this change is subject to anthropogenic influence arising from processes that are only beginning to be understood. Increasing concentrations of atmospheric radiatively active trace gases are being inadvertently affected by fossil fuel combustion; but other activities of industry, agriculture, forestry, changing land-use practices, waste disposal, and transportation also affect the chemical composition of the atmosphere. The measured and projected changes of the atmospheric concentrations of radiatively active trace gases have been modeled and estimated to predict changes in the global climate. Accuracy and reliability of these predictions are the subject of considerable debate among scientists and other concerned individuals, groups, and governmental agencies throughout the world. The objective of this book is to provide a review of current knowledge on the measurement of radiatively active trace gases in agricultural ecosystems and the effect of agriculture on the atmospheric concentrations of these gases. This book is compiled from written papers presented at a symposium entitled, Agroecosystem Effects on Radiatively Important Trace Gases and Global Climate Change, held at the American Society of Agronomy Meetings in Denver, CO, 27 Oct.-1 Nov. 1991. Fourteen chapters have been processed separately for inclusion in the appropriate data bases.

Not Available

1993-01-01

97

Importance of ATM Mutations and Polymorphisms in Breast Cancer and Radiation Sensitivity.  

National Technical Information Service (NTIS)

The objective of my 4-year Career Development Award was to determine whether ATM heterozygosity contributes to breast cancer development and radiation injury. We sequenced the ATM cDNA of 93 breast cancer patients, 22 of whom experienced a normal tissue i...

T. A. Buchholz

2001-01-01

98

Melanocortin 1 receptor genotype: an important determinant of the damage response of melanocytes to ultraviolet radiation.  

PubMed

The melanocortin 1 receptor gene is a main determinant of human pigmentation, and a melanoma susceptibility gene, because its variants that are strongly associated with red hair color increase melanoma risk. To test experimentally the association between melanocortin 1 receptor genotype and melanoma susceptibility, we compared the responses of primary human melanocyte cultures naturally expressing different melanocortin 1 receptor variants to ?-melanocortin and ultraviolet radiation. We found that expression of 2 red hair variants abolished the response to ?-melanocortin and its photoprotective effects, evidenced by lack of functional coupling of the receptor, and absence of reduction in ultraviolet radiation-induced hydrogen peroxide generation or enhancement of repair of DNA photoproducts, respectively. These variants had different heterozygous effects on receptor function. Microarray data confirmed the observed differences in responses of melanocytes with functional vs. nonfunctional receptor to ?-melanocortin and ultraviolet radiation, and identified DNA repair and antioxidant genes that are modulated by ?-melanocortin. Our findings highlight the molecular mechanisms by which the melanocortin 1 receptor genotype controls genomic stability of and the mutagenic effect of ultraviolet radiation on human melanocytes. PMID:20519635

Kadekaro, Ana Luisa; Leachman, Sancy; Kavanagh, Renny J; Swope, Viki; Cassidy, Pamela; Supp, Dorothy; Sartor, Maureen; Schwemberger, Sandy; Babcock, George; Wakamatsu, Kazumasa; Ito, Shosuke; Koshoffer, Amy; Boissy, Raymond E; Manga, Prashiela; Sturm, Richard A; Abdel-Malek, Zalfa A

2010-10-01

99

The importance of the diurnal and annual cycle of air traffic for contrail radiative forcing  

Microsoft Academic Search

Air traffic condensation trails, or contrails, are believed to have a net atmospheric warming effect(1), although one that is currently small compared to that induced by other sources of human emissions. However, the comparably large growth rate of air traffic requires an improved understanding of the resulting impact of aircraft radiative forcing on climate(2). Contrails have an effect on the

Nicola Stuber; Piers Forster; G. Radel; Keith Shine

2006-01-01

100

Experimental detection of the influence of radiation damages upon the diffusion behaviour of solar wind noble gases in single grains of moon dust  

Microsoft Academic Search

The linear heating technique was applied to study the diffusion of solar ; wind implanted noble gases (⁴He and ²°Ne) in single grains of moon ; dust. The samples were heated in a diffusion oven with a heating rate of 6 K\\/min ; from room temperature to 1,200 K. The thus expelled gases were detected in highly ; sensitive mass

H. Ducati

1973-01-01

101

Efficient abatement of different greenhouse gases.  

National Technical Information Service (NTIS)

Although CO(sub 2) is the most important greenhouse gas, there are a number of other greenhouse gases which are important for the development of the climate. An efficient climate policy should in principle be related to emissions of all climate gases, wei...

M. Hoel I. Isaksen

1993-01-01

102

On the importance of prompt oxygen changes for hypofractionated radiation treatments  

NASA Astrophysics Data System (ADS)

This discussion is motivated by observations of prompt oxygen changes occurring prior to a significant number of cancer cells dying (permanently stopping their metabolic activity) from therapeutic agents like large doses of ionizing radiation. Such changes must be from changes in the vasculature that supplies the tissue or from the metabolic changes in the tissue itself. An adapted linear-quadratic treatment is used to estimate the cell survival variation magnitudes from repair and reoxygenation from a two-fraction treatment in which the second fraction would happen prior to significant cell death from the first fraction, in the large fraction limit. It is clear the effects of oxygen changes are likely to be the most significant factor for hypofractionation because of large radiation doses. It is a larger effect than repair. Optimal dose timing should be determined by the peak oxygen timing. A call is made to prioritize near real time measurements of oxygen dynamics in tumors undergoing hypofractionated treatments in order to make these treatments adaptable and patient-specific.

Kissick, Michael; Campos, David; van der Kogel, Albert; Kimple, Randall

2013-10-01

103

Importance of the deep ocean for estimating decadal changes in Earth's radiation balance  

NASA Astrophysics Data System (ADS)

We use control run data from three Met Office Hadley Centre climate models to investigate the relationship between: net top-of-atmosphere radiation balance (TOA), globally averaged sea surface temperature (SST); and globally averaged ocean heat content (OHC) on decadal timescales. All three models show substantial decadal variability in SST, which could easily mask the long-term warming associated with anthropogenic climate change over a decade. Regression analyses are used to estimate the uncertainty of TOA, given the trend in SST or OHC over the same period. We show that decadal trends in SST are only weakly indicative of changes in TOA. Trends in total OHC strongly constrain TOA, since the ocean is the primary heat store in the Earth System. Integrating OHC over increasing model levels, provides an increasingly good indication of TOA changes. To achieve a given accuracy in TOA estimated from OHC we find that there is a trade-off between measuring for longer or deeper. Our model results suggest that there is potential for substantial improvement in our ability to monitor Earth's radiation balance by more comprehensive observation of the global ocean.

Palmer, Matthew D.; McNeall, Douglas J.; Dunstone, Nick J.

2011-07-01

104

Radiation track structure is not only important in determining the response of traversed cells but also non-traversed cells.  

NASA Astrophysics Data System (ADS)

The spatial distribution of energy deposition on the scale of DNA, cells and tissue for both low and high-LET radiation is important in determining the subsequent biological response in DNA, cells and ultimately people. In irradiated cells, the biological response has been shown to be critically dependant on the clustering of damage to DNA on the nanometre scale, with high-LET radiation not only producing a higher frequency of complex DNA damage but also typically producing damage sites of greater complexity than those produced by low-LET radiation. The differences in the energy distribution on the micron/cellular scale are also important with regards to chromosome aberration formation. The traversal of a cell by a high-LET track typically produces a non-homogeneous dose distribution through a cell nucleus and correlated DNA double-strand breaks along the path, resulting in an increased probability of complex chromosomal rearrangements (3 or more breaks in 2 or more chromosomes). In addition, in recent years it has become increasing clear that cells do not act in isolation, but the ultimate response of a cell or tissue is dependent on intercellular signalling. This becomes increasingly important at the low doses, or low dose rates, associated with typical human exposures. In order to help characterise the underlying mechanism of intercellular signalling, and how they are perturbed following exposure to ionising radiation, a previously well-defined model system of intercellular induction of apoptosis (IIA) was used, where neighbouring normal cells selectively eliminate transformed cells through cytokine (TGF-beta) and ROS/RNS signalling. The rate of apoptosis in unirradiated transformed cells was found to be enhanced even after extremely low doses of both low-LET (2 mGy gamma-rays) and high-LET (0.3 mGy alpha-particles) with the enhancement independent of dose and radiation quality at medium to high doses. The level of stimulation was found to be also dependent on the fraction of cells irradiated, cell type, levels of TGF-beta, distance between cell populations and oxygen concentration. The study shows that the stimulation of intercellular signalling by radiation required both sufficient energy deposition within irradiated cells and fraction of cells irradiated, with the response dependent on radiation quality only at low doses or when a small fraction of cells are irradiated. These results will be discussed in terms of their potential implications to risks associated with typical human exposures.

Hill, Mark

2012-07-01

105

The Importance of Technical Reachback in the Adjudication of Radiation Alarms  

SciTech Connect

The large-scale deployment of radiation sensors at borders, ports-of-entry and other locations carries two disparate priorities: the reliable detection and identification of threat materials and the rapid characterization of non-threat materials comprised of naturally occurring radioactive materials (NORM) and legitimate radioactive materials in streams of commerce. These priorities are partially achieved through the technologies contained in the detection systems and the procedures developed for their operation. However, questions and ambiguities will occur. Without established capabilities and procedures for the operators of these detector systems to 'reach back' to trained spectroscopists and appropriate subject matter experts, the system will likely experience an unacceptable number of response operations and delays resolving alarms. Technical reachback operations need to be able to address the priorities discussed above while causing minimal perturbations in the flow of legitimate streams of commerce. Yet when necessary, reachback needs to be able to rapidly mobilize the appropriate response assets.

Buckley, W M; Allen, R W

2009-03-18

106

Inorganic fluorescent screen properties important for MeV radiation imagery  

SciTech Connect

This report summarizes observed properties of inorganic fluorescent screens that are important in imaging experiments that rely on MeV photons and neutrons. The summary is based on our earlier, more comprehensive report. Recent, preliminary results of Monte Carlo calculations that complement that work are also discussed.

Berzins, G.J.; Lumpkin, A.H.; Smith, H.L.

1984-12-01

107

Some important issues in developing basic radiation protection recommendations: dosimetric aspects  

SciTech Connect

Some aspects of the difficulties encountered in the dose equivalent system used in radiation protection are explored and recent work to improve these deficiencies described. The philosophical advantages of a departure from the dose equivalent-based system and its replacement by a risk-based system are briefly discussed. The definition of dose equivalent and the debate concerning its physical dimensions and units are described. Dose equivalent is related to other physiological quantities in physics and the treatment of these quantities in the International System of Units compared. Practical problems in the determination of dose equivalent are illustrated using neutrons as an example. The proliferation of operational quantities for the evaluation of neutron dose equivalent and the concomitant potential for confusion when determinations of neutron dose equivalent are intercompared is described. The evaluation of fluence to dose equivalent conversion coefficients and methods of interpolation between recommended values are described. Particular emphasis is given to the accuracy and precision of dose equivalent estimation. Recent work of a Task Group of the ICRP to improve recommended conversion coefficients and the work of an ICRU committee to improve the definition of operational dose equivalent quantities is summarized. 125 references, 11 figures, 4 tables.

Thomas, R.H.

1984-03-01

108

Is Mc1r an important regulator of non-pigmentary responses to UV radiation?  

PubMed

MC1R is recognized for its role in the regulation of melanin pigmentation. In addition, many investigators believe that it also plays a crucial role in immunomodulation (immunosuppression) and in melanogenesis-independent protective responses against ultraviolet radiation (UVR). Surprisingly, Wolnicka-Glubisz et al. have shown that loss of function in the MC1R has no effect on inflammatory responses and immunosuppression induced by UVR in C57BL/6 mice as well as on the degree of UVA-induced DNA damage in the epidermis and dermis. These findings, by challenging the existing dogmas on the precise role of MC1R in non-pigmentary responses to the UVR, mandate further research to either validate the presented data or to define to which degree these phenomena are restricted to the C57BL/6 mouse model or are applicable to other species including humans. The alternative target for immunomodulation is represented by MC3R. However, cutaneous expression of MC3R remains to be demonstrated. PMID:24279915

Zmijewski, Michal A; Slominski, Andrzej T

2013-12-01

109

On the possibility of the generation of high harmonics with photon energies greater than 10 keV upon interaction of intense mid-IR radiation with neutral gases  

NASA Astrophysics Data System (ADS)

Based on the analytical quantum-mechanical description in the framework of the modified strong-field approximation, we have investigated high harmonic generation of mid-IR laser radiation in neutral gases taking into account the depletion of bound atomic levels of the working medium and the electron magnetic drift in a high-intensity laser field. The possibility is shown to generate high-order harmonics with photon energies greater than 10 keV under irradiation of helium atoms by intense femtosecond laser pulses with a centre wavelength of 8 – 10.6 ?m.

Emelina, A. S.; Emelin, M. Yu; Ryabikin, M. Yu

2014-05-01

110

Biologically important radiation damage in DNA. Annual progress report, May 1, 1993--January 31, 1994  

SciTech Connect

Most DNA damage by the hydroxyl radical is confined to the bases, and this base damage represents an important component of locally multiply demanded sites (LMOS). The yields of the major damaged bases have been determined by gas chromatography mass spectrometry. For our propose, it was necessary to convert a known fraction of these damaged bases to strand breaks and then assay these labile sites as the increase in strand break yield over the normally observed level. Three potential agents by which this strategy of conversion of base damage to strand break could be implemented were identified in the original application: 1, Sl nuclease; 2, piperidine; and 3, base damage specific enzymes.

Ward, J.F.

1994-03-01

111

The importance of tissue segmentation for dose calculations for kilovoltage radiation therapy  

PubMed Central

Purpose: The aim of this work was to evaluate the effect of tissue segmentation on the accuracy of Monte Carlo (MC) dose calculations for kilovoltage radiation therapy, which are commonly used in preclinical radiotherapy studies and are also being revisited as a clinical treatment modality. The feasibility of tissue segmentation routinely done on the basis of differences in tissue mass densities was studied and a new segmentation scheme based on differences in effective atomic numbers was developed.Methods: MC dose calculations in a cylindrical mouse phantom with small cylindrical inhomogeneities consisting of 34 ICRU-44 tissues were performed using the EGSnrc?BEAMnrc and DOSXYZnrc codes. The dose to tissue was calculated for five different kilovoltage beams currently used in small animal radiotherapy: a microCT 120 kV beam, two 225 kV beams filtered with either 4 mm of Al or 0.5 mm of Cu, a heavily filtered 320 kV beam, and a 192Ir beam. The mean doses to the 34 ICRU-44 tissues as a function of tissue mass density and effective atomic number and beam energy were studied. A treatment plan for an orthotopic lung tumor model was created, and the dose distribution was calculated for three tissue segmentation schemes using 4, 8, and 39 tissue bins to assess the significance of the simulation results for kilovoltage radiotherapy.Results: In our model, incorrect assignment of adipose tissue to muscle caused dose calculation differences of 27%, 13%, and 7% for the 120 kV beam and the 225 kV beams filtered with 4 mm Al and 0.5 mm Cu, respectively. For the heavily filtered 320 kV beam and a 192Ir source, potential dose calculation differences due to tissue mis-assignment were below 4%. There was no clear relationship between the dose to tissue and its mass density for x-ray beams generated by tube potentials equal or less than 225 kV. A second order polynomial fit approximated well the absorbed dose to tissue as a function of effective atomic number for these beams. In the mouse study, the 120 kV beam dose to bone was overestimated by 100% and underestimated by 10% for the 4 and 8-tissue segmentation schemes compared to the 39-tissue segmentation scheme, respectively. Dose to adipose tissue was overestimated by 30% and underestimated by 10%, respectively. In general, organ at risk (OAR) doses were overestimated in the 4-tissue and the 8-tissue segmentation schemes compared to the 39-tissue segmentation.Conclusions: Tissue segmentation was shown to be a key parameter for dose calculations with kilovoltage beams used in small animal radiotherapy when an x-ray tube with a potential ?225 kV is used as a source. A new tissue segmentation scheme with 39 tissues based on effective number differences derived from mass density differences has been implemented.

Bazalova, Magdalena; Graves, Edward E.

2011-01-01

112

Electrical breakdown of gases  

Microsoft Academic Search

A collection of individual works on electrical discharges is presented. Topics covered include: fundamental processes in the electrical breakdown of gases; vacuum breakdown; spark breakdown in uniform fields; corona discharge; spark breakdown in non-uniform fields; breakdown voltage characteristics; irradiation and time lags; high-frequency breakdown of gases; laser-induced electrical breakdown of gases; spark channels; and electrode phenomena. (GHT)

J. M. Meek; J. D. Craggs

1978-01-01

113

Separation of polar gases from nonpolar gases  

DOEpatents

The separation of polar gases from nonpolar gases may be effected by passing a mixture of nonpolar gases over the face of a multicomponent membrane at separation conditions. The multicomponent membrane which is used to effect the separation will comprise a mixture of a glycol plasticizer having a molecular weight of from about 200 to about 600 and an organic polymer cast on a porous support. The porous support is pretreated prior to casting of the mixture thereon by contact with a polyhydric alcohol whereby the pores of the support are altered, thus adding to the increased permeability of the polar gas.

Kulprathipanja, S.

1986-08-19

114

Separation of polar gases from nonpolar gases  

DOEpatents

The separation of polar gases from nonpolar gases may be effected by passing a mixture of nonpolar gases over the face of a multicomponent membrane at separation conditions. The multicomponent membrane which is used to effect the separation will comprise a mixture of a glycol plasticizer having a molecular weight of from about 200 to about 600 and an organic polymer cast on a porous support. The porous support is pretreated prior to casting of the mixture thereon by contact with a polyhydric alcohol whereby the pores of the support are altered, thus adding to the increased permeability of the polar gas.

Kulprathipanja, Santi (Hoffman Estates, IL)

1986-01-01

115

Separation of polar gases from nonpolar gases  

DOEpatents

Polar gases such as hydrogen sulfide, sulfur dioxide and ammonia may be separated from nonpolar gases such as methane, nitrogen, hydrogen or carbon dioxide by passing a mixture of polar and nonpolar gases over the face of a multicomponent membrane at separation conditions. The multicomponent membrane which is used to effect the separation will comprise a mixture of a glycol plasticizer having a molecular weight of from about 200 to about 600 and an organic polymer cast on a porous support. The use of such membranes as exemplified by polyethylene glycol and silicon rubber composited on polysulfone will permit greater selectivity accompanied by a high flux rate in the separation process.

Kulprathipanja, S.; Kulkarni, S.S.

1986-08-26

116

Separation of polar gases from nonpolar gases  

DOEpatents

Polar gases such as hydrogen sulfide, sulfur dioxide and ammonia may be separated from nonpolar gases such as methane, nitrogen, hydrogen or carbon dioxide by passing a mixture of polar and nonpolar gases over the face of a multicomponent membrane at separation conditions. The multicomponent membrane which is used to effect the separation will comprise a mixture of a glycol plasticizer having a molecular weight of from about 200 to about 600 and an organic polymer cast on a porous support. The use of such membranes as exemplified by polyethylene glycol and silicon rubber composited on polysulfone will permit greater selectivity accompanied by a high flux rate in the separation process.

Kulprathipanja, Santi (Hoffman Estates, IL) [Hoffman Estates, IL; Kulkarni, Sudhir S. (Hoffman Estates, IL) [Hoffman Estates, IL

1986-01-01

117

Improved Cloud-Radiation Parameterization for GCMs through the ARM Program. Final Progress Report.  

National Technical Information Service (NTIS)

Climate sensitivity is an important determinant of climate change. In terms of global climate response, climate sensitivity determines the magnitude of climate change due to radiative forcings by greenhouse gases. The IPCC reports have pointed out that mu...

J. T. Kiehl

2004-01-01

118

Emissions of biogenic sulfur gases from northern bogs and fens  

NASA Technical Reports Server (NTRS)

Sulfur gases are important components of the global cycle of S. They contribute to the acidity of precipitation and they influence global radiation balance and climate. The role of terrestrial sources of biogenic S and their effect on atmospheric chemistry remain as major unanswered questions in our understanding of the natural S cycle. The role of northern wetlands as sources and sinks of gaseous S by measuring rates of S gas exchange as a function of season, hydrologic conditions, and gradients in tropic status was investigated. Experiments were conducted in wetlands in New Hampshire, particularly a poor fen, and in Mire 239, a poor fen at the Experimental Lakes Area (ELA) in Ontario. Emissions were determined using Teflon enclosures, gas cryotrapping methods and gas chromatography (GC) with flame photometric detection. Dynamic (sweep flow) and static enclosures were employed which yielded similar results. Dissolved S gases and methane were determined by gas stripping followed by GC.

Demello, William Zamboni; Hines, Mark E.; Bayley, Suzanne E.

1992-01-01

119

RNA Sequencing and Proteogenomics Reveal the Importance of Leaderless mRNAs in the Radiation-Tolerant Bacterium Deinococcus deserti  

PubMed Central

Deinococcus deserti is a desiccation- and radiation-tolerant desert bacterium. Differential RNA sequencing (RNA-seq) was performed to explore the specificities of its transcriptome. Strikingly, for 1,174 (60%) mRNAs, the transcription start site was found exactly at (916 cases, 47%) or very close to the translation initiation codon AUG or GUG. Such proportion of leaderless mRNAs, which may resemble ancestral mRNAs, is unprecedented for a bacterial species. Proteomics showed that leaderless mRNAs are efficiently translated in D. deserti. Interestingly, we also found 173 additional transcripts with a 5?-AUG or 5?-GUG that would make them competent for ribosome binding and translation into novel small polypeptides. Fourteen of these are predicted to be leader peptides involved in transcription attenuation. Another 30 correlated with new gene predictions and/or showed conservation with annotated and nonannotated genes in other Deinococcus species, and five of these novel polypeptides were indeed detected by mass spectrometry. The data also allowed reannotation of the start codon position of 257 genes, including several DNA repair genes. Moreover, several novel highly radiation-induced genes were found, and their potential roles are discussed. On the basis of our RNA-seq and proteogenomics data, we propose that translation of many of the novel leaderless transcripts, which may have resulted from single-nucleotide changes and maintained by selective pressure, provides a new explanation for the generation of a cellular pool of small peptides important for protection of proteins against oxidation and thus for radiation/desiccation tolerance and adaptation to harsh environmental conditions.

de Groot, Arjan; Roche, David; Fernandez, Bernard; Ludanyi, Monika; Cruveiller, Stephane; Pignol, David; Vallenet, David; Armengaud, Jean; Blanchard, Laurence

2014-01-01

120

Radial Diffusion of Outer Radiation Belt Electrons - Quantifying the Relative Importance of ULF wave Electric and Magnetic Fields  

NASA Astrophysics Data System (ADS)

MeV energy electrons are thought to be transported inwards from the plasma sheet into the radiation belts under the action of radial diffusion. Waves in the ultra-low frequency (ULF) band have frequencies which can be drift resonant with these electrons in the outer zone suggesting the potential for strong interactions, and enhanced radial diffusion. The diffusion coefficients depend on the power spectral density (PSD) of the waves electric and magnetic fields in space in the equatorial plane. Here we use over a solar cycle of ground magnetometer data to determined the electric field PSD in space and in-situ GOES and AMPTE data to obtain the magnetic field PSD. The diffusion coefficients derived from these PSD values allows us to quantify the relative importance of the electric and magnetic field diffusion terms. The commonly used analytic expressions presented in Brautigam and Albert [2000] indicate that magnetic diffusion dominates over the electric diffusion by over an order of magnitude. However, the magnetic diffusion coefficients we derive from the in-situ PSD measurements indicate that the Brautigam and Albert [2000] magnetic diffusion term is over an order of magnitude too high and that during high Kp intervals at L<4 the electric field diffusion term can become over two orders of magnitude greater than the magnetic diffusion term. In addition, radial diffusion simulations of electrons driven by these diffusion coefficients will be presented illustrating that both the electric and magnetic field diffusion coefficients may play an important role in the dynamics and energization of the Earth's outer radiation belt region.

Ozeke, L.; Mann, I. R.; Murphy, K. R.; Rae, J.; Milling, D. K.

2011-12-01

121

Emissions of greenhouse gases in the United States, 1985--1990  

SciTech Connect

The Earth`s capacity to support life depends on the moderating influences of gases that envelop the planet and warm its surface and protect it from harmful radiation. These gases are referred to as ``greenhouse gases.`` Their warming capacity, called ``the greenhouse effect,`` is essential to maintaining a climate hospitable to all plant, animal, and human life. In recent years, however, there has been increasing concern that human activity may be affecting the intricate balance between the Earth`s absorption of heat from the sun and its capacity to reradiate excess heat back into space. Emissions of greenhouse gases from human activities may be an important mechanism that affects global climate. Thus, research is intensifying to improve our understanding of the role human activities might play in influencing atmospheric concentrations of greenhouse gases. On the basis of scientific findings of the past few decades, the US Government and the international community at large are now taking steps toward stabilizing greenhouse gas emissions. This report contributes to that process. Mandated by Congress this report provides estimates of US emissions of the principal greenhouse gases--carbon dioxide, methane, nitrous oxide, chlorofluorcarbons, carbon monoxide, nitrogen oxides, and nonmethane volatile organic compounds. Estimates are for the period 1985 to 1990. Preliminary estimates for 1991 have also been included, whenever data were available.

Not Available

1993-11-10

122

ANALYSIS OF PROTOCOL GASES  

EPA Science Inventory

In 1992, EPA's Atmospheric Research and Exposure Assessment Laboratory initiated a nationwide QA program on the suppliers of EPA Protocol Gases. he program has three goals: to increase the acceptance and use of Protocol Gases by the air monitoring community, to provide a QA check...

123

The contribution from emissions of different gases to the enhanced greenhouse effect. Appendix B  

SciTech Connect

The main purpose of this paper is to compare the different contributions, that mankind has made to perturbing the atmosphere`s radiative balance. We have, and will continue to perturb both the balance of outgoing long-wave radiation and the balance of incoming short-wave radiation. Human activities since preindustrial times have caused a substantial enhancement of the greenhouse effect, a process involving the absorption of outgoing long-wave radiation which leads to a warming of the lower atmosphere. Because the atmosphere`s short-wave radiative balance is affected by the presence of small particles (aerosols) produced by the oxidation of sulphur compounds, anthropogenic emissions of sulphur dioxide (SO{sub 2}) have also caused a perturbation of the overall balance. The greenhouse gases we will consider are, in order of importance: carbon dioxide (CO{sub 2}), Methane (CH{sub 4}), nitrous oxide (N{sub 2}O) and the halocarbons. We use observed and model-based concentration data together with the most recent information relating concentrations to radiative forcing to estimate the individual contributions of the different gases to the changing radiative balance of the atmosphere. We also estimate the ranges of uncertainty in each of these estimates. We base all results on the 1992 IPCC emissions scenarios IS92a-f. We begin with a summary of 1990 conditions, then consider each gas separately (but lumping the halocarbons into a single group), to compare their relative importance.

Wigley, T.M.L.

1993-01-01

124

Future global warming from atmospheric trace gases  

Microsoft Academic Search

The effect of the continuing addition of trace gases to the atmosphere due to human activity on the future global surface temperatures is examined. The radiative properties of the atmosphere are reviewed, and the atmospheric increase in carbon dioxide, halocarbons, nitrous oxide, methane, and ozone is discusssed. Future scenarios resulting from these trends and their implications for climate change are

R. E. Dickinson; R. J. Cicerone

1986-01-01

125

Evolution of sulfur gases during coal pyrolysis  

SciTech Connect

The yields and rates of evolution of sulfur gases depend not only on pyrolysis conditions but also on the coal itself. The organic/inorganic forms of sulfur, as well as the secondary reactions of sulfur gases with solids and with other pyrolysis-generated gases, play an important role. Monitoring the time- and temperature-dependent evolution of sulfur-containing gases provides insight into the sulfur chemistry affecting evolution profiles. programmed-temperature studies of sulfur gas evolution often have been limited to H{sub 2}S. In some cases, all sulfur gases have been studied collectively by reducing or oxidizing them to H{sub 2}S or SO{sub 2}. Recently, Calkins studied the evolution of individual sulfur species from a Pyroprobe using Gas Chromatograph/Mass Spectrometer (GC/MS) and from isothermal flash pyrolysis. Boudou et al. also identified some individual sulfur gases from isothermal pyrolysis using a Curie-point reactor in combination with MS, GC, and GC/MS. In this study, the authors monitored the real-time evolution of sulfur gases during slow-heating pyrolysis via a triple quadrupole mass spectrometer (TQMS). They also monitored the evolution of hydrocarbon gases, water, and carbon oxides. They compared the evolution profiles of sulfur gases and related them to the rank of the coal, the organic and inorganic sources of sulfur in each coal sample, and the evolution of other pyrolysis-generated gases. The authors also studied the extend of secondary reactions by varying the pyrolysis conditions.

Oh, M.S.; Burnham, A.K.; Crawford, R.W. (Lawrence Livermore National Laboratory, CA (USA))

1988-01-01

126

Decomposition of greenhouse gases by plasma  

Microsoft Academic Search

The topic of decomposition and reduction of greenhouse gases is becoming an important issue in tackling the global warming\\u000a effect since several years ago. Several technologies, including plasma-utilized process, were proposed to improve the treatment\\u000a ability for the destruction of green house gases usually emitted by industrial activities. In this review paper, the application\\u000a of plasma to reduce the emission

Antonius Indarto; Jae-Wook Choi; Hwaung Lee; Hyung Keun Song

2008-01-01

127

Greenhouse gases and the metallurgical process industry  

Microsoft Academic Search

The Kyoto Protocol of December 1997 highlighted the importance of greenhouse gas emissions. The metallurgical process industry\\u000a is a contributor to these emissions and would be seriously affected by measures curtailing them. The present lecture offers\\u000a a brief review of the greenhouse effect, the sources of greenhouse gases, the potential effect of these gases on global warming,\\u000a the response of

Claude H. P. Lupis; C. H. P

1999-01-01

128

Signatures of Annual and Seasonal Variations of CO2 and Other Greenhouse Gases from Comparisons between NOAA TOVS Observations and Radiation Model Simulations  

Microsoft Academic Search

Since 1979, sensors on board the National Oceanic and Atmospheric Administration (NOAA) series of polar meteorological satellites have provided continuous measurements of the earth's surface and atmosphere. One of these sensors, the Television Infrared Observational Satellite (TIROS-N) Operational Vertical Sounder (TOVS), observes earth-emitted radiation in the infrared-with the High-Resolution Infrared Sounder (HIRS)-and in the microwave-with the Microwave Sounding Unit (MSU)-portions

Alain Chédin; Soumia Serrar; Raymond Armante; Noëlle A. Scott; Anthony Hollingsworth

2002-01-01

129

Spectra of scattered photons in large absorbers and their importance for the values of radiation weighting factor wR.  

PubMed

In its review of the present values of radiation weighting factor w(R) and of possible revisions of this factor, the German Radiation Protection Commission has recommended to maintain the approach of ICRP 60 to base the selection of the w(R) value for a given radiation (e.g. fission neutrons) on observed values of the relative biological effectiveness (RBE) of this radiation 'regardless of whether the reference radiation is X rays or gamma rays'. The physical background of the German recommendation is the buildup of a strong field of energy-degraded Compton scattered photons in the human body if exposed to an external field of high-energy photons, so that the total radiation field inside the body is a mixture comprising low and high photon energies. Therefore, it is appropriate that the selection of the w(R) value of the given radiation is guided by RBE values averaged over X rays and gamma rays as the reference radiations. In support of this rationale, the present paper provides a sample of Monte Carlo calculated scattered photon spectra in large absorbers exposed to high-energy photons. Depth-dependent fractional dose contributions of the scattered photons are tabulated for incident energies from 1 to 10 MeV, and estimates of the influence of their degraded energies on the biological effectiveness of the incoming radiation are presented. Accordingly, we point out that it is appropriate to use, for the purposes of 'risk projection', RBE values averaged over X and gamma reference radiations. PMID:15273346

Harder, D; Petoussi-Henss, N; Regulla, D; Zankl, M; Dietze, G

2004-01-01

130

Latitudinal variation in ambient UV-B radiation is an important determinant of Lolium perenne forage production, quality, and digestibility  

PubMed Central

Few studies to date have considered the responses of agriculturally important forage grasses to UV-B radiation. Yet grasses such as Lolium perenne have a wide current distribution, representing exposure to a significant variation in ambient UV-B. The current study investigated the responses of L. perenne (cv. AberDart) to a simulated latitudinal gradient of UV-B exposure, representing biologically effective UV-B doses at simulated 70, 60, 50, 40, and 30° N latitudes. Aspects of growth, soluble compounds, and digestibility were assessed, and results are discussed in relation to UV-B effects on forage properties and the implications for livestock and bio-ethanol production. Aboveground biomass production was reduced by approximately 12.67% with every 1 kJ m–2 day–1 increase in biologically weighted UV-B. As a result, plants grown in the highest UV-B treatment had a total biomass of just 13.7% of controls. Total flavonoids were increased by approximately 76% by all UV-B treatments, while hydroxycinnamic acids increased in proportion to the UV-B dose. Conversely, the digestibility of the aboveground biomass and concentrations of soluble fructans were reduced by UV-B exposure, although soluble sucrose, glucose, and fructose concentrations were unaffected. These results highlight the capacity for UV-B to directly affect forage productivity and chemistry, with negative consequences for digestibility and bioethanol production. Results emphasize the need for future development and distribution of L. perenne varieties to take UV-B irradiance into consideration.

Gwynn-Jones, Dylan

2013-01-01

131

Carbon uptake in a marine diatom during acute exposure to ultraviolet B radiation: Relative importance of damage and repair  

SciTech Connect

Experiments on a marine diatom, Thalassiosira pseudonana (Hustedt) clone 3H, demonstrate that under moderate photon flux densities (75 [mu]mol quanta [center dot] m[sup [minus]2][center dot]s[sup [minus]1]) of visible light inhibition of photosynthesis by supplemental ultraviolet (UV) radiation (UV-B: 280-320 nm) is well described as a hyperbolic function of UV-B irradiance for time scales of 0.5-4 h. Results are consistent with predictions of a recently developed model of photosynthesis under the influence of UV and visible irradiance. Although net destruction of chlorophyll occurs during a 4-h exposure to UV-B, and the effect is a function of exposure, the principal effect of UV-B is a decrease in chlorophyll-specific photosynthetic rate. The dependence of photoinhibition on dosage rate, rather than cumulative dose, and the hyperbolic shape of the relationship are consistent with net photoinhibition being an equilibrium between damage and repair. The ratio of damage to repair is estimated by a mathematical analysis of the inhibition of photosynthesis during exposures to UV-B. A nitrate-limited culture was much more sensitive to UV-B than were the nutrient-replete cultures, but the kinetics of photoinhibition were similar. The analysis suggests that the nutrient-limited culture was much more sensitive than the nutrient-replete cultures because repair or turnover of critical proteins associated with photosynthesis is inhibited. An inhibitor of chloroplast protein synthesis was used to suppress repair processes. Photoinhibition by UV-B was enhanced, and inhibition was a function of cumulative dose, as expected if damage were not countered by repair. The fundamental importance of repair processes should be considered in the design of field experiments and models of UV-B effects in the environment, especially in the context of vertical mixing. Repair processes must also be considered whenever biological weighting functions are developed. 69 refs., 6 figs., 3 tabs.

Lesser, M. P. (Bigelow Lab. for Ocean Sciences, West Boothbay Harbor, ME (United States)); Cullen, J.J. (Bigelow Lab. for Ocean Sciences, West Boothbay Harbor, ME (United States) Dalhousie Univ., Halifax, Nova Scotia (Canada)); Neale, P.J. (Bigelow Lab. for Ocean Sciences, West Boothbay Harbor, ME (United States) Univ. of California, Berkeley, CA (United States))

1994-04-01

132

THE IMPORTANCE OF XUV RADIATION AS A SOLUTION TO THE P V MASS LOSS RATE DISCREPANCY IN O STARS  

SciTech Connect

A controversy has developed regarding the stellar wind mass loss rates in O stars. The current consensus is that these winds may be clumped, which implies that all previously derived mass loss rates using density-squared diagnostics are overestimated by a factor of {approx}2. However, arguments based on Far Ultraviolet Spectroscopic Explorer (FUSE) observations of the P V resonance line doublet suggest that these rates should be smaller by another order of magnitude, provided that P V is the dominant phosphorous ion among these stars. Although a large mass loss rate reduction would have a range of undesirable consequences, it does provide a straightforward explanation of the unexpected symmetric and un-shifted X-ray emission-line profiles observed in high-energy resolution spectra. But acceptance of such a large reduction then leads to a contradiction with an important observed X-ray property: the correlation between He-like ion source radii and their equivalent X-ray continuum optical depth unity radii. Here we examine the phosphorous ionization balance since the P V fractional abundance, q (P V), is fundamental to understanding the magnitude of this mass loss reduction. We find that strong emission line radiation in the XUV energy band (defined here as 54 to 124 eV) can significantly reduce q (P V). Furthermore, owing to the unique energy distribution of these XUV lines, there is a negligible impact on the S V fractional abundance (a key component in the FUSE mass loss argument). We conclude that large reductions in O star mass loss rates are not required, and the X-ray optical depth unity relation remains valid.

Waldron, W. L. [Eureka Scientific Inc., 2452 Delmer Street, Oakland, CA 94602 (United States); Cassinelli, J. P. [Department of Astronomy, University of Wisconsin-Madison, Madison, WI 53711 (United States)], E-mail: wwaldron@satx.rr.com, E-mail: cassinelli@astro.wisc.edu

2010-03-01

133

Transformations in Solidified Gases.  

National Technical Information Service (NTIS)

Transformations in solidified gases have been studied in very few laboratories yet they are governed by factors of wide scientific interest, some of which are very different from those involved in the commonly studied transformations of metallic substance...

C. S. Barrett

1968-01-01

134

Excitation of O(3S) resonance radiation in inelastic collisions between O(5S) metastables and O2 and N2 gases  

Microsoft Academic Search

The excitation of the 3S state of atomic oxygen with subsequent emission of 1304-Å resonance radiation was observed in inelastic collisions between O(5S) metastables and O2 and N2 molecules according to the process O(5S)+X-->O(3S)+X-->O(3P)+X+hnu(1304 Å), where X is O2 or N2. The cross section for this endothermic process was measured for metastable kinetic energies from threshold at 0.5 eV to

H. U. Kiefl; W. L. Borst; J. Fricke

1980-01-01

135

The ice record of greenhouse gases  

SciTech Connect

Gases trapped in polar ice proved our most direct record of the changes in greenhouse gas levels during the past 150,000 years. The best documented trace-gas records are for CO[sub 2] and CH[sub 4]. The measurements corresponding to the industrial period document the recent changes in growth rate. The variability observed over the last 1000 years constrains the possible feedbacks of a climate change on the trace gases under similar conditions as exist today. Changes in the levels of greenhouse gases during the glacial-interglacial cycle overall paralleled, at least at high southern latitudes, changes in temperature; this relation suggests that greenhouse gases play an important role as an amplifier of the initial orbital forcing of Earth's climated and also helps to assess the feedbacks on the biogeochemical cycles in a climate system in which the components are changing at different rates.

Raynaud, D.; Barnola, J.M.; Chappellaz, J.; Delmas, R.J.; Lorius, C. (Cenre National de la Recherche Scientifique, Saint Martin d'Heres Cedex (France)); Jouzel, J. (Commissariat a l'Energie Atomique Saclay, Yvette (France))

1993-02-12

136

Remote monitoring of volcanic gases using passive Fourier transform spectroscopy  

Microsoft Academic Search

Volcanic gases provide important insights on the internal workings of volcanoes and changes in their composition and total flux can warn of impending changes in a volcano`s eruptive state. In addition, volcanoes are important contributors to the earth`s atmosphere, and understanding this volcanic contribution is crucial for unraveling the effect of anthropogenic gases on the global climate. Studies of volcanic

S. P. Love; F. Goff; D. Counce; S. C. Schmidt; C. Siebe; H. Delgado

1999-01-01

137

Effects of radiation on rat respiratory epithelial cells: Critical target cell populations and the importance of cell-cell interactions  

NASA Astrophysics Data System (ADS)

The oncongenic effects of radiation on rat respiratory tissues are modulated in vivo within the intact tissue. The degree of modulation as well as the mechanism whereby modulation occurs appears to be different for different types of ionizing radiations. A combined cell culture -in vivo model is described. This model has been developed to evaluate the influence of the host and tissue environment on development and expression of the neoplastic phenotype in irradiated rat trachea. Our data indicates that the potentially oncogenic effects of neutrons, X Rays, and ?-particles are different depending on the exposure conditions employed and the conditions under which exposed cells are maintained following exposure.

Terzaghi-Howe, M.; Ford, J.

1994-10-01

138

Gases: Characteristics and Properties  

NSDL National Science Digital Library

The first site related to ideal gas, called Ideal and Real Gas Laws, is maintained by Liina Ladon of Townsen University (1). Visitors can read about the properties of ideal gases, what the ideal gas law is, how to use it, and much more. The next site, titled Gas Laws, (2) is offered by the Ohio State University Department of Chemistry. This interactive site contains Shockwave movies of animations and audio files that describe what a gas is, the Ideal Gas Law equation, mixtures of gases, and problems using the ideal gas law. The University of Oregon site, Virtual Laboratory, teaches about the ideal gas law on the Welcome to the Pressure Chamber page (3). Those who enjoy online interaction will enjoy being able to control the action of a piston in a pressure chamber to see how the gases inside react. The fourth site includes another fun multimedia activity related to ideal gases provided by the Department of Physics and Astronomy at Western Washington University. The Air Filled Balloon in Liquid Nitrogen (4) movie shows an actual experiment of the effects on a balloon that's covered with liquid nitrogen. The page contains some additional information on the science behind the observations. The next site, called Ideal Gas Equations (5) is an online calculator that's part of Kean University's Department of Geology and Meteorology Web site. Users can calculate the pressure, volume, or temperature of a gas by inputting known variables into the various forms. Several methods and variations of calculating the values are provided as well as brief instructions. The next page from North Carolina State University's Basic Concepts in Environmental Science Web site is called Characteristics of Gases (6). Part of a larger learning module, the lesson plans objective is to use the ideal gas law to determine gas volumes at different absolute temperatures and absolute pressures. Everything needed to conduct the activity is provided including links to a volume calculator and practice problems. The seventh site is another animation that illustrates how gases react, called Molecular Model for an Ideal Gas (7). By changing the number of molecules in the chamber, their velocity, and the pressure and width of the container, users get to see how the molecules react to the conditions. The last site, Gases and Their Properties, is maintained by the Electronic Teaching Assistance Program(8). Students learn about the history of gas science, how gas laws describe ideal gases, what Dalton's Law and Graham's Law are, and much more.

Brieske, Joel A.

139

Solids, Liquids, and Gases  

NSDL National Science Digital Library

In this project you will research solids, liquids, and gases. By the end of this project you will be able to answer the question: Can you tell what is alike and different between solids, liquids, and gases? Read the song about matter. song with music about matter Record your observations on the organizer provided by the teacher. On the diagram write the word solid in one of the circles. Write liquid in one of the circles and write gas in the last circle. As you collect your information write your information under ...

Sibley, Ms.

2009-10-22

140

Radiative heat loss in gentoo penguin (Pygoscelis papua) adults and chicks and the importance of warm feet.  

PubMed

Adult penguins and their chicks differ considerably in their apparent body insulation. The chicks are covered in down, whereas the adults have the short, hard body feathers characteristic of the family, so mechanisms of heat loss may vary considerably between the two groups. We examined radiative heat loss by measuring body surface temperatures of gentoo penguins (Pygoscelis papua) in Antarctica. At the time the birds were considered to be in their thermoneutral zone, and there was little or no wind. Measurements of infrared emission were made on breeding adults and in large downy, and thermally independent, chicks in relation to environmental temperature. All 28 external body surface sites measured were positively correlated with ambient temperature, although there was considerable intersite variability in the relationship between site temperature and ambient temperature. Foot temperature increased most rapidly per degree ambient temperature increase, followed by the flippers, followed by the trunk. This pattern was particularly pronounced in the chicks, indicating that the exceptional heat-loss capacities of the feet may counteract for the reduced capacity of the flippers. Net heat transfer by radiation was examined using Stefan-Boltzmann's law and preliminary data on the surface area of a gentoo penguin body. This showed that between ground temperatures of 5 degrees and 15 degrees C overall heat transfer remains essentially constant, although radiative heat loss from the trunk decreases, this being counteracted by increasing heat transfer from the flippers and feet. Over the same temperature range the specific radiation heat transfer of the feet increased approximately 100 times faster per degree ambient temperature increase than did that of the flippers. This and the bimodality in foot temperature found in the study birds even under constant ambient temperatures indicate that within the thermoneutral zone heat loss by radiation in gentoo penguins is primarily executed using the feet, through which the blood circulates in pulses. PMID:9754529

Wilson, R P; Adelung, D; Latorre, L

1998-01-01

141

Thermodynamic models of the chemistry of lunar volcanic gases  

NASA Technical Reports Server (NTRS)

Thermodynamic models and mass-balance arguments are used to constrain the chemistry of lunar volcanic gases. The results predict that lunar gases were dominated by reduced C and S gases such as CO, COS, CS2, S2. The more oxidized gases CO2 and SO2 were also important, but only in limited temperature ranges. Gases such as Cl2, CCl4, and CF4 were more abundant than HF and HCl, which were the two major H compounds in the lunar gases. Chlorides and fluorides were important species for transporting many volatile and ore-forming metals, and the implications for fractionating and concentrating metals into lunar ore-deposits merit further study.

Fegley, Bruce, Jr.

1991-01-01

142

Deforestation and Greenhouse Gases.  

National Technical Information Service (NTIS)

Human activities produce large amounts of greenhouse gases (GHGs), primarily carbon dioxide (CO2), and thus contribute to global warming. The use of fossil fuels is the primary source of CO2 emissions, but the removal of trees from forested land has also ...

2012-01-01

143

Reduction in greenhouse gases  

Microsoft Academic Search

It needs extensive use of new and improved technology, by improvement in energy efficiency, change of fuels, introduction of new energy sources and abatement \\/ sequestration of greenhouse gases in order to achieve reductions in emissions without affecting standards of living. Some of these technologies are widely available now; others are in their research stages. This panel paper looks into

D. Vujatovic; L. L. Lai

2003-01-01

144

Interaction of Radiation with Matter.  

National Technical Information Service (NTIS)

The paper discusses the work in the general area of electromagnetic properties of various systems, i.e. gases, solids, plasmas, the absorption of radiation in gases as well as in the thermodynamic properties of systems. (Author)

H. Mendlowitz

1970-01-01

145

Glass Membrane For Controlled Diffusion Of Gases  

SciTech Connect

A glass structure for controlled permeability of gases includes a glass vessel. The glass vessel has walls and a hollow center for receiving a gas. The glass vessel contains a metal oxide dopant formed with at least one metal selected from the group consisting of transition metals and rare earth metals for controlling diffusion of the gas through the walls of the glass vessel. The vessel releases the gas through its walls upon exposure to a radiation source.

Shelby, James E. (Alfred Station, NY); Kenyon, Brian E. (Pittsburgh, PA)

2001-05-15

146

Line-driven Disk Winds in Active Galactic Nuclei: The Critical Importance of Ionization and Radiative Transfer  

NASA Astrophysics Data System (ADS)

Accretion disk winds are thought to produce many of the characteristic features seen in the spectra of active galactic nuclei (AGNs) and quasi-stellar objects (QSOs). These outflows also represent a natural form of feedback between the central supermassive black hole and its host galaxy. The mechanism for driving this mass loss remains unknown, although radiation pressure mediated by spectral lines is a leading candidate. Here, we calculate the ionization state of, and emergent spectra for, the hydrodynamic simulation of a line-driven disk wind previously presented by Proga & Kallman. To achieve this, we carry out a comprehensive Monte Carlo simulation of the radiative transfer through, and energy exchange within, the predicted outflow. We find that the wind is much more ionized than originally estimated. This is in part because it is much more difficult to shield any wind regions effectively when the outflow itself is allowed to reprocess and redirect ionizing photons. As a result, the calculated spectrum that would be observed from this particular outflow solution would not contain the ultraviolet spectral lines that are observed in many AGN/QSOs. Furthermore, the wind is so highly ionized that line driving would not actually be efficient. This does not necessarily mean that line-driven winds are not viable. However, our work does illustrate that in order to arrive at a self-consistent model of line-driven disk winds in AGN/QSO, it will be critical to include a more detailed treatment of radiative transfer and ionization in the next generation of hydrodynamic simulations.

Higginbottom, Nick; Proga, Daniel; Knigge, Christian; Long, Knox S.; Matthews, James H.; Sim, Stuart A.

2014-07-01

147

Greenhouse role of trace gases  

SciTech Connect

Atmospheric scientists are emphasizing the role of trace gases as important factors in a future substantial global increase in temperature. They estimate that, in 1980, trace gases contributed more than half as much to a greenhouse effect as did increased carbon dioxide. From 1880 to 1980, CO/sub 2/ increased from about 275 parts per million (ppm) to 339 ppm. The principal relevant trace gases in 1980 were Ch/sub 4/, 1.6 ppm; N/sub 2/O, 0.3 ppm; CCl/sub 2/F/sub 2/, 0.00028 ppm. CCl/sub 3/F, 0.00018 ppm, and O/sub 3/, which increased in the troposphere substantially over earlier values. Methane (CH/sub 4/) is at present the most effective greenhouse trace gas. Its concentration has been increasing about 1% per year since 1950. The total content in the atmosphere is about 5000 million tons. Methane is destroyed slowly, mainly in the trophosphere, by the reactive OH. Residence time for CH/sub 4/ is 5 to 10 years. This implies an annual addition of at least 500 million tons to hold the level constant. Growth of 1% per year requires an extra addition on the order of 50 million tons. Principal sources of CH/sub 4/ appear to be ruminant animals, organic-rich sediments, and rice paddies. A complicating factor in estimating trends in CH/sub 4/ distribution is the competition of CO for OH. Emissions of CO have been increasing, and they destroy OH that otherwise might react with CH/sub 4/.

Abelson, P.H.

1986-03-14

148

Volcanic Gases and Their Effects  

MedlinePLUS

... hydrothermal systems. At high pressures deep beneath the earth's surface, volcanic gases are dissolved in molten rock. ... volcanic gases can rise tens of kilometers into Earth's atmosphere during large explosive eruptions. Once airborne, the ...

149

SN52, a novel nuclear factor-?B inhibitor, blocks nuclear import of RelB:p52 dimer and sensitizes prostate cancer cells to ionizing radiation  

PubMed Central

The activation of nuclear factor-?B (NF-?B) is thought to protect cancer cells against therapy-induced cytotoxicity. RelB, a member of the NF-?B family in the alternative pathway, is uniquely expressed at a high level in prostate cancer with high Gleason scores. Here, we show that ionizing radiation (IR) enhances nuclear import of RelB, leading to up-regulation of its target gene, manganese superoxide dismutase (MnSOD), and renders prostate cancer cells resistant to IR. To selectively block RelB nuclear import, we designed a cell-permeable SN52 peptide, a variant of the SN50 peptide that has been shown to block nuclear import of NF-?B family members in the classic pathway. Inhibition of IR-induced NF-?B activation by SN50 and SN52 was achieved by selectively interrupting the association of p50 and p52 with nuclear import factors importin-?1 and importin-?1. Importantly, SN52 seems to be more efficient for radiosensitization of prostate cancer cells at clinically relevant radiation doses and has less cytotoxicity to normal prostate epithelial cells compared with the toxicity observed with SN50. These results suggest that targeting the alternative pathway is a promising approach to selectively radiosensitize prostate cancers and that SN52 may serve as a prototype biological agent for sensitizing prostate cancers to clinically relevant doses of IR.

Xu, Yong; Fang, Fang; St. Clair, Daret K.; Sompol, Pradoldej; Josson, Sajni; St. Clair, William H.

2009-01-01

150

Detecting oil dissolved gases using carbon nanotubes sensor  

Microsoft Academic Search

The detection and analysis of dissolved gases in oil is an important means to determine the early latent faults of oil-immersed power transformer. A dissolved gases in oil detection method is presented based on carbon nanotubes sensor. A kind of MWNTs (Multi-wall carbon nanotubes) gas sensor modified by mixed acid was developed based on printed circuit board to detect dissolved

Tao Chang; Xiaoxing Zhang; Wangting Liu; Caixin Sun

2010-01-01

151

Refractivity of combustion gases  

SciTech Connect

A comprehensive survey of the refractive indices and dispersions of gases that are found in practical or laboratory combustion experiments is reported. A critical evaluation was used to obtain recommended values where experimental data are available. Where they are not, sums of atomic and bond refractivities were used. The results are tabulated as molar refractivities at common laser wavelengths and as the constants of Cauchy dispersion formulas.

Gardiner, W.C. Jr.

1981-02-01

152

Sudden releases of gases  

NASA Astrophysics Data System (ADS)

Conurbations all over the world have enlarged for numberless years. The accidental or intentional releases of gases become more frequent. Therefore, these crises situations have to be studied. The aim of this paper is to describe experiments examining these processes that were carried out in the laboratory of Environmental Aerodynamics of the Institute of Thermomechanics AS CR in Nový Knín. Results show huge puff variability from replica to replica.

Chaloupecká, Hana; Ja?our, Zbyn?k; Jur?áková, Klára; Kuka?ka, Libor; Nosek, Št?pán

2014-03-01

153

Greenhouse Gases Exposed  

NSDL National Science Digital Library

In this activity, students learn about the relationship between greenhouse gases and global warming through a simple teacher demo or hands-on lab activity. Everyday materials are used: beakers, baking soda, vinegar, candle, thermometers, heat source such as a goose-necked lamp, etc. Students shine a light onto three thermometers: a control, an upside down beaker w/ a thermometer and air, and a beaker in which CO2 had been poured.

Babcock, Victoria; Collie, Janet; Ecohealth

154

Advanced Global Atmospheric Gases Experiment (AGAGE)  

NASA Technical Reports Server (NTRS)

AGAGE comprises continuous high frequency in-situ gas chromatographic FID/ECD measurements of two biogenic/anthropogenic gases (CH4, N2O) and five anthropogenic gases (CFCl3, CF2Cl2, CH3CCl3, CF2ClCFCl2, CCl4) which are carried out at five globally distributed sites (Ireland, California, Barbados, Samoa, Tasmania). Also, high frequency in-situ gas-chromatographic mass spectrometric measurements of about 30 species including chlorofluorocarbon replacements and many natural halocarbons are made at two sites (Ireland, Tasmania), and will soon begin at the other three sites. Finally, high frequency in-situ gas chromatographic HgO-RD measurements of CO and H2 are performed at two sites (Ireland, Tasmania). The goal is quantitative determination of the sources, sinks, and circulation of these environmentally important gases.

Prinn, Ronald G.

2001-01-01

155

Radiation  

Cancer.gov

DCEG researchers carry out a broad-based research program designed to identify, understand, and quantify the risk of cancer in populations exposed to medical, occupational, or environmental radiation. They study ionizing radiation exposures (e.g., x-rays,

156

Radiation Is an Important Component of Multimodality Therapy for Pediatric Non-Pineal Supratentorial Primitive Neuroectodermal Tumors  

SciTech Connect

Purpose: To review a historical cohort of pediatric patients with supratentorial primitive neuroectodermal tumors (sPNET), to clarify the role of radiation in the treatment of these tumors. Patients and Methods: Fifteen children aged <18 years with non-pineal sPNETs diagnosed between 1992 and 2006 were identified. Initial therapy consisted of surgical resection and chemotherapy in all patients and up-front radiotherapy (RT) in 5 patients. Five patients had RT at the time of progression, and 5 received no RT whatever. Kaplan-Meier estimates of overall survival were then calculated. Results: The median follow-up from diagnosis for all patients was 31 months (range, 0.5-165 months) and for surviving patients was 49 months (range, 10-165). Of the 5 patients who received up-front RT, all were alive without evidence of disease at a median follow-up of 50 months (range, 25-165 months). Only 5 of the 10 patients who did not receive up-front RT were alive at last follow-up. There was a statistically significant difference in overall survival between the patient group that received up-front RT and the group that did not (p = 0.048). In addition, we found a trend toward a statistically significant improvement in overall survival for those patients who received gross total resections (p = 0.10). Conclusions: Up-front RT and gross total resection may confer a survival benefit in patients with sPNET. Local failure was the dominant pattern of recurrence. Efforts should be made to determine patients most likely to have local failure exclusively or as a first recurrence, in order to delay or eliminate craniospinal irradiation.

McBride, Sean M.; Daganzo, Sally M. [Department of Radiation Oncology, University of California-San Francisco, San Francisco, CA (United States); Banerjee, Anuradha [Department of Pediatrics, University of California-San Francisco, San Francisco, CA (United States); Gupta, Nalin; Lamborn, Kathleen R.; Prados, Michael D.; Berger, Mitchel S. [Department of Neurological Surgery and Brain Tumor Research Center, University of California-San Francisco, San Francisco, CA (United States); Wara, William M. [Department of Radiation Oncology, University of California-San Francisco, San Francisco, CA (United States); Haas-Kogan, Daphne A. [Department of Radiation Oncology, University of California-San Francisco, San Francisco, CA (United States); Department of Neurological Surgery and Brain Tumor Research Center, University of California-San Francisco, San Francisco, CA (United States)], E-mail: dhaaskogan@radonc.ucsf.edu

2008-12-01

157

Biogeophysical effects of land use on climate: Model simulations of radiative forcing and large-scale temperature change  

Microsoft Academic Search

Changes in land cover affect climate through the surface energy and moisture budgets. Here we assess the importance of these biogeophysical effects for present-day climate, and quantify the radiative forcing of historical climate change by land use change for comparison with radiative forcings due to anthropogenic changes in greenhouse gases and aerosols. We also discuss the implications of biogeophysical effects

Richard A. Betts; Peter D. Falloon; Kees Klein Goldewijk; Navin Ramankutty

2007-01-01

158

A generic biokinetic model for noble gases with application to radon.  

PubMed

To facilitate the estimation of radiation doses from intake of radionuclides, the International Commission on Radiological Protection (ICRP) publishes dose coefficients (dose per unit intake) based on reference biokinetic and dosimetric models. The ICRP generally has not provided biokinetic models or dose coefficients for intake of noble gases, but plans to provide such information for (222)Rn and other important radioisotopes of noble gases in a forthcoming series of reports on occupational intake of radionuclides (OIR). This paper proposes a generic biokinetic model framework for noble gases and develops parameter values for radon. The framework is tailored to applications in radiation protection and is consistent with a physiologically based biokinetic modelling scheme adopted for the OIR series. Parameter values for a noble gas are based largely on a blood flow model and physical laws governing transfer of a non-reactive and soluble gas between materials. Model predictions for radon are shown to be consistent with results of controlled studies of its biokinetics in human subjects. PMID:23612507

Leggett, Rich; Marsh, James; Gregoratto, Demetrio; Blanchardon, Eric

2013-06-01

159

Greenhouse Gases Observation from the GOSAT Satellite  

NASA Astrophysics Data System (ADS)

The Greenhouse gases Observing Satellite (GOSAT) is a satellite to monitor the carbon dioxide (CO2) and the methane (CH4) globally from orbit. The two instruments are accommodated on GOSAT. The Greenhouse gases Observing Sensor is a Fourier-Transform Spectrometer (FTS), which detects gas absorption spectra of the solar short wave infrared (SWIR) reflected on the earth_fs surface as well as of the thermal infrared (TIR) radiated from the ground and the atmosphere. The FTS is capable of detecting three narrow bands (0.76, 1.6, and 2 micron) and a wide band (5.5-14.3 micron) with 0.2 cm-1 spectral resolution. The cloud and aerosol sensor is an imager of ultraviolet (UV), visible, and SWIR to correct cloud and aerosol interference. The presentation includes the instrument design, pre-launch calibration and onboard calibration schemes; as well as, some test results using the Bread Board Model (BBM).

Kuze, A.; Kondo, K.; Kaneko, Y.; Hamazaki, T.

2005-12-01

160

Emission of Greenhouse Gases (GHGs) from Burning of Biomass in Brick Kilns  

Microsoft Academic Search

Burning of biomass fuel is an important source of emission of greenhouse gases in the environment. Due to anthropogenic activities, concentrations of greenhouse gases are increasing, having a direct effect on the world's climate, which poses serious threat for mankind. In the present study, emission of greenhouse gases has been attributed to the burning of biomass fuel, i.e., fire wood

Syed Nasir Ahmed Tahir; Muhammed Rafique

2009-01-01

161

Non-C02 greenhouse gases; all gases count  

Microsoft Academic Search

Under the Kyoto Protocol, a group of countries commit themselves to reduce the emissions of greenhouse gases to some 5% below the 1990 level. Countries can decide to spread their reduction commitment over several gases to lower compliance costs. Employing a multi-gas strategy can offer considerable efficiency gains because of the widely diverging marginal abatement cost for the different emission

Willemien Kets; Gerard Verweij

2005-01-01

162

Thermodynamics of Quantum Gases  

NASA Astrophysics Data System (ADS)

Ultracold dilute atomic gases can be considered as model systems to address some pending problem in Many-Body physics that occur in condensed matter systems, nuclear physics, and astrophysics. We have developed a general method to probe with high precision the thermodynamics of locally homogeneous ultracold Bose and Fermi gases [1,2,3]. This method allows stringent tests of recent many-body theories. For attractive spin 1/2 fermions with tunable interaction, we will show that the gas thermodynamic properties can continuously change from those of weakly interacting Cooper pairs described by Bardeen-Cooper-Schrieffer theory to those of strongly bound molecules undergoing Bose-Einstein condensation. First, we focus on the finite-temperature Equation of State (EoS) of the unpolarized unitary gas. Surprisingly, the low-temperature properties of the strongly interacting normal phase are well described by Fermi liquid theory and we localize the superfluid phase transition. A detailed comparison with theories including Monte-Carlo calculations has revealed some surprises and the Lee-Huang-Yang corrections for low-density bosonic and fermionic superfluids are directly measured for the first time. Despite orders of magnitude difference in density and temperature, our equation of state can be used to describe low density neutron matter such as the outer shell of neutron stars.[4pt] [1] S. Nascimbène, N. Navon, K. Jiang, F. Chevy, and C. Salomon, Nature 463, 1057 (2010)[0pt] [2] N. Navon, S. Nascimbène, F. Chevy, and C. Salomon, Science 328, 729 (2010)[0pt] [3] N. Navon, S. Piatecki, K. Günter, B. Rem, T. C Nguyen, F. Chevy, W. Krauth, and C. Salomon, arXiv:1103.4449

Salomon, Christophe

2011-06-01

163

Advanced Global Atmospheric Gases Experiment (AGAGE)  

NASA Technical Reports Server (NTRS)

We seek funding from NASA for the third year (2005) of the four-year period January 1, 2003 - December 31, 2006 for continued support of the MIT contributions to the multi-national global atmospheric trace species measurement program entitled Advanced Global Atmospheric Gases Experiment (AGAGE). The case for real-time high-frequency measurement networks like AGAGE is very strong and the observations and their interpretation are widely recognized for their importance to ozone depletion and climate change studies and to verification issues arising from the Montreal Protocol (ozone) and Kyoto Protocol (climate). The proposed AGAGE program is distinguished by its capability to measure over the globe at high frequency almost all of the important species in the Montreal Protocol and almost all of the significant non-CO2 gases in the Kyoto Protocol.

Prinn, Ronald G.; Kurylo, Michael (Technical Monitor)

2004-01-01

164

The humidification of anaesthetic gases: Its importance and control  

Microsoft Academic Search

\\u000a Résumé  Les auteurs ont décrit les différentes définitions concernant ?humidité des gaz ?anesthésie et ont étudie les facteurs capables\\u000a ?influencer sa régulation. Ils ont de plus démontré les effets néfastes de ?emploi des gaz secs qui déssèchent les muqueuses\\u000a respiratoires et élèvent le pourcentage des complications pulmonaires qui suivent ?anesthésie. Une revue du débit de vapeur\\u000a ?eau des systèmes en usage

Jack Chalon; Mahgul Ali; Sivam Ramanathan; Herman Turndorf

1979-01-01

165

Radiation  

NASA Video Gallery

Outside the protective cocoon of Earth's atmosphere, the universe is full of harmful radiation. Astronauts who live and work in space are exposed not only to ultraviolet rays but also to space radi...

166

Greenhouse gases: Sources and emissions.  

National Technical Information Service (NTIS)

The current interest in the ''greenhouse'' issue stems from the observation that the concentrations of such gases as CO(sub 2), CH(sub 4), N(sub 2)O, CFCl(sub 3) and CF(sub 2)Cl(sub 2) have been increasing. Changes in the concentrations of these gases hol...

J. Edmonds D. J. Wuebbles

1991-01-01

167

Kinetic Molecular Theory of Gases  

NSDL National Science Digital Library

Applets dealing with the meaning of the Maxwell distribution of gases and pressure of gases are discussed. The Maxwell distribution experiment allow the user to explore the most probable speed of gas molecules. The pressure experiment allows the user to explore the effects of size and mass on collision rate, direction, and relative speed of gas molecules within a fixed volume.

Blauch, David N.

168

Greenhouse Gases: A Closer Look  

NSDL National Science Digital Library

This lesson covers different aspects of the major greenhouse gases - water vapor, carbon dioxide, methane, nitrous oxides and CFCs - including some of the ways in which human activities are affecting the atmospheric concentrations of these key greenhouse gases. This is lesson six in a nine-lesson module about climate change.

Science, King'S C.

169

Radiators  

SciTech Connect

A heat-exchange radiator is connected to a fluid flow circuit by a connector which provides one member of an interengageable spigot and socket pair for push-fit, fluid-tight, engagement between the connector and the radiator, with latching formations at least one of which is resilient. Preferably the connector carries the spigot which tapers and engages with a socket of corresponding shape, the spigot carrying an O-ring seal and either latching fingers or a resilient latching circlip.

Webster, D. M.

1985-07-30

170

Impacts of microphysics, radiation and environmental winds in mid-latitude and tropical squall-line systems, and their climatic implications  

Microsoft Academic Search

Cloud-radiation feedback has been identified as the most important factor limiting general circulation models (GCMS) to further progress in climate change research (Cess et al., 1989). It is also regarded as a major uncertainty in estimating the impact of greenhouse gases on climate simulations. As a result, many GCMs showed high sensitivity to the treatment of clouds and cloud radiative

Hung-Neng

1994-01-01

171

Climate-chemical interactions and effects of changing atmospheric trace gases  

SciTech Connect

The problem concerning the greenhouse effects of human activities has broadened in scope from the CO2-climate problem to the trace gas-climate problem. The climate effects of non-CO2 trace gases are strongly governed by interactions between chemistry, radiation, and dynamics. We discuss in detail the nature of the trace gas radiative heating and describe the importance of radiative-chemical interactions within the troposphere and the stratosphere. We make an assessment of the trace gas effects on troposphere-stratosphere temperature trends for the period covering the preindustrial era to the present and for the next several decades. Non-CO2 greenhouse gases in the atmosphere are now adding to the greenhouse effect by an amount comparable to the effect of CO2. The rate of decadal increase of the total greenhouse forcing is now 3--6 times greater than the mean rate for the period 1850--1960. Time-dependent calculations with a simplified one-dimensional diffusive ocean model suggest that a surface warming about 0.4--0.8 K should have occurred during 1850 to 1980. For the various trace gas scenarios considered in this study, the equilibrium surface warming for the period 1980 to 2030 ranges from 0.8 to 4.1 K. This wide range in the projected warming is due to the range in the assumed scenario as well as due to the threefold uncertainty in the sensitivity of climate models.

Ramanathan, V.; Callis, L.; Cess, R.; Hansen, J.; Isaksen, I.; Kuhn, W.; Lacis, A.; Luther, F.; Mahlman, J.; Reck, R.; and others

1987-08-01

172

Discharges In Electronegative Gases  

NASA Astrophysics Data System (ADS)

This talk will come in three parts. First, the early work in electronegative plasmas, principally by Emeleus and co-workers in Iodine, and by Massey and co-workers in Oxygen. They were at opposite ends of the ``spectrum'' of electronegativity - the ratio of negative ion density to electron density. Secondly, we cover in more detail work in Oxygen, where in retrospect we know that too many parameters were included to reveal the underlying structure of electronegative plasmas. That is associated with Edgley and von Engel, and later with Ferriera and co-workers. From there until the present day we describe work coming from different directions, showing that by questioning prior assumptions, we have arrived at our present understanding. The basic elements are, that in general there is a negative ion core, surrounded by a conventional plasma, and that at low pressures the situation is significantly different from higher pressures. The talk will seek to avoid mathematical complexity and concentrate on the physics, explaining the reason for previous differences, and show the way forward for a more Complete understanding of the very complex problem of strongly electronegative plasmas and their structure when diluted by rare gases. All of this involves a multiplicity of ion species of both signs, and a variety of reaction rates.

Franklin, R. N.

2008-10-01

173

The significance of agricultural sources of greenhouse gases  

Microsoft Academic Search

The impact of development of land for agriculture and agricultural production practices on emissions of greenhouse gases is reviewed and evaluated within the context of anthropogenic radiative forcing of climate. Combined, these activities are estimated to contribute about 25%, 65%, and 90% of total anthropogenic emissions of CO2, CH4, and N2O, respectively. Agriculture is also a significant contributor to global

John M. Duxbury

1994-01-01

174

Multiple direct and sequential Auger effect in the rare gases  

Microsoft Academic Search

The use of a magnetic bottle spectrometer with synchrotron radiation allows multi dimensional electron spectroscopy to be performed by detecting in coincidence all electrons (2, 3, 4) ejected in multiple ionization events. Multiple Auger effect following inner-shell ionization can be investigated in this way. Application of the technique to rare gases (Xe 4d and Kr 3d) double Auger decay reveals

F. Penent; P. Lablanquie; J. Palaudoux; L. Andric; T. Aoto; K. Ito; Y. Hikosaka; R. Feifel; J. H. D. Eland

2006-01-01

175

Use of dissociating gases in Brayton cycle space power systems  

Microsoft Academic Search

In this paper an analysis of the use of dissociating gases in Brayton Cycle Space Power Systems has been presented. It has been shown that the development of higher efficiency cycles is necessary for minimizing isotope costs which have a dominant influence on total cycle economics. A dissociating gas Brayton cycle has been optimized for maximum efficiency and minimum radiator

Hua Min Huang; Rakesh Govind

1988-01-01

176

Greenhouse effect of chlorofluorocarbons and other trace gases  

Microsoft Academic Search

A comparison is made of the radiative (greenhouse) forcing of the climate system due to changes of atmospheric chlorofluorocarbons and other trace gases. It is found that CFCs, defined to include chlorofluorocarbons, chlorocarbons, and fluorocarbons, now provide about one-quater of current annual increases in anthropogenic greenhouse climate forcing. If the growth rates of CFC production in the early 1970s had

James Hansen; Andrew Lacis; Michael Prather

1989-01-01

177

Radiation dosimetry.  

PubMed Central

This article summarizes the basic facts about the measurement of ionizing radiation, usually referred to as radiation dosimetry. The article defines the common radiation quantities and units; gives typical levels of natural radiation and medical exposures; and describes the most important biological effects of radiation and the methods used to measure radiation. Finally, a proposal is made for a new radiation risk unit to make radiation risks more understandable to nonspecialists.

Cameron, J

1991-01-01

178

40 CFR 89.312 - Analytical gases.  

Code of Federal Regulations, 2010 CFR

...concentration of the diluted gases may be determined to within ±2 percent. (d) Oxygen interference check gases shall contain propane with...ppmC hydrocarbon. The three oxygen interference gases shall contain 21% ± 1%...

2010-07-01

179

Waste Anesthetic Gases: Occupational Hazards in Hospitals.  

National Technical Information Service (NTIS)

Waste anesthetic gases are small amounts of volatile anesthetic gases that leak from the patient's anesthetic breathing circuit into the air of operating rooms during delivery of anesthesia. These gases may also be exhaled by patients recovering from anes...

2007-01-01

180

Investigating and Using Biomass Gases  

NSDL National Science Digital Library

In this activity, learners will be introduced to biomass gasification and will generate their own biomass gases. Learners generate these gases everyday on their own and find it quite amusing, but this time theyâll do it by heating wood pellets or wood splints in a test tube. They will collect the resulting gases and use the gas to roast a marshmallow. Learners will also evaluate which biomass fuel is the best either according to their own criteria or by examining the volume of gas produced by each type of fuel.

Benson, Eric; Highfill, Melissa

2012-07-03

181

Noble gases in the moon  

NASA Technical Reports Server (NTRS)

The abundance and isotopic composition of helium, neon, argon, krypton, and xenon which were released by stepwise heating of lunar fines (15601.64) and (15271.65) were measured spectrometrically. The results of a composition of noble gases released from the lunar fines with noble gases in meteorites and in the earth are presented along with the isotopic composition of noble gases in lunar fines, in meteorites, and in the atmosphere. A study of two isotopically distinct components of trapped xenon in carbonaceous chondrites is also included.

Manuel, O. K.; Srinivasan, B.; Hennecke, E. W.; Sinclair, D. E.

1972-01-01

182

Environmental Implications of Anesthetic Gases  

PubMed Central

For several decades, anesthetic gases have greatly enhanced the comfort and outcome for patients during surgery. The benefits of these agents have heavily outweighed the risks. In recent years, the attention towards their overall contribution to global climate change and the environment has increased. Anesthesia providers have a responsibility to minimize unnecessary atmospheric pollution by utilizing techniques that can lessen any adverse effects of these gases on the environment. Moreover, health care facilities that use anesthetic gases are accountable for ensuring that all anesthesia equipment, including the scavenging system, is effective and routinely maintained. Implementing preventive practices and simple strategies can promote the safest and most healthy environment.

Yasny, Jeffrey S.; White, Jennifer

2012-01-01

183

New spectral features of stratospheric trace gases  

NASA Technical Reports Server (NTRS)

A new Michelson-type interferometer system operating in the infrared at very high resolution (0.002 to 0.003 wavenumber FWHM) was used to record numerous balloon-borne solar absorption spectra of the stratosphere, ground-based solar absorption spectra, and laboratory spectra of molecules of atmospheric interest. Results obtained are reported for several important stratospheric trace gases, HNO3, ClONO2, HO2NO2, NO2, and COF2, in the 8 to 12 micron spectral region. Many features of these gases were identified in the stratospheric spectra. Comparison of the spectra with line-by-line simulations shows previous spectral parameters are often inadequate. New analysis of high resolution laboratory and atmospheric spectra and improved theoretical calculations will be required for all bands. Preliminary versions of several sets of improved line parameters are presented.

Goldman, A.; Murcray, F. J.; Blatherwick, R. D.; Kosters, J. J.; Murcray, F. H.; Murcray, D. G.; Rinsland, C. P.

1990-01-01

184

Impact of carbon dioxide, trace gases, and climate change on global agriculture  

SciTech Connect

Global climate change is one of several important issues that will command the attention of policymakers and scientist in the 1990s. The evidence that concentrations of carbon dioxide (CO{sub 2}), and other gases are increasing in the atmosphere is irrefutable. The evidence, and the knowledge that CO{sub 2} and trace gases may absorb thermal radiation sufficient to warm the atmosphere, has prompted much speculation that ensuing atmospheric warming may lead to changes in the distribution of precipitation, and of crop adaptation and productivity, that would alter the world supply of food and fiber. The implications of this speculation are compelling for agronomists, because agronomists are stewards of the world's food supply and of the natural resources that are used to produce food. Agronomists have a pivotal role in conducting the research needed to anticipate crop response to climate changes, and in informing policymakers and the general public about the adequacy of our knowledge. In this publication agronomists assess the current status of scientific knowledge about the putative role of greenhouse gases in global climate change and report their findings.

Not Available

1990-01-01

185

Abiotic Mechanisms for the Formation of Greenhouse Gases from Heterogeneous Atmospheric Chemistry and Photochemistry  

NASA Astrophysics Data System (ADS)

Atmospheric aerosol particles such as mineral dust can undergo interfacial, heterogeneous reactions that can be involved in both the formation and destruction of important greenhouse gases. This talk will provide an overview of some of these reactions and will focus on the formation of atmospheric nitrous oxide from ammonium nitrate coated dust particles that can be initiated with simulated solar radiation. Although nitrous oxide is an important greenhouse gas and a primary cause of stratospheric ozone destruction, there remain missing sources in the nitrous oxide budget. Nitrous oxide production by the abiotic mechanism discussed here is expected globally from both megacities and agricultural areas and may become more important under future projected changes in anthropogenic emissions.

Grassian, V. H.

2012-12-01

186

Climate-chemical interactions and effects of changing atmospheric trace gases  

NASA Technical Reports Server (NTRS)

The paper considers trace gas-climate effects including the greenhouse effect of polyatomic trace gases, the nature of the radiative-chemical interactions, and radiative-dynamical interactions in the stratosphere, and the role of these effects in governing stratospheric climate change. Special consideration is given to recent developments in the investigations of the role of oceans in governing the transient climate responses, and a time-dependent estimate of the potential trace gas warming from the preindustrial era to the early 21st century. The importance of interacting modeling and observational efforts is emphasized. One of the problems remaining on the observational front is the lack of certainty in current estimates of the rate of growth of CO, O3, and NOx; the primary challenge is the design of a strategy that will minimize the sampling errors.

Ramanathan, V.; Callis, L.; Cess, R.; Hansen, J.; Isaksen, I.

1987-01-01

187

Climate-chemical interactions and effects of changing atmospheric trace gases  

NASA Astrophysics Data System (ADS)

The paper considers trace gas-climate effects including the greenhouse effect of polyatomic trace gases, the nature of the radiative-chemical interactions, and radiative-dynamical interactions in the stratosphere, and the role of these effects in governing stratospheric climate change. Special consideration is given to recent developments in the investigations of the role of oceans in governing the transient climate responses, and a time-dependent estimate of the potential trace gas warming from the preindustrial era to the early 21st century. The importance of interacting modeling and observational efforts is emphasized. One of the problems remaining on the observational front is the lack of certainty in current estimates of the rate of growth of CO, O3, and NOx; the primary challenge is the design of a strategy that will minimize the sampling errors.

Ramanathan, V.; Callis, L.; Cess, R.; Hansen, J.; Isaksen, I.

1987-08-01

188

Degenerate Quantum Gases of Strontium  

NASA Astrophysics Data System (ADS)

Degenerate quantum gases of alkaline-earth-like elements open new opportunities in research areas ranging from molecular physics to the study of strongly correlated systems. These experiments exploit the rich electronic structure of these elements, which is markedly different from the one of other species for which quantum degeneracy has been attained. Specifically, alkaline-earth-like atoms, such as strontium, feature metastable triplet states, narrow intercombination lines, and a nonmagnetic, closed-shell ground state. This review covers the creation of quantum degenerate gases of strontium and the first experiments performed with this new system. It focuses on laser-cooling and evaporation schemes, which enable the creation of Bose-Einstein condensates and degenerate Fermi gases of all strontium isotopes, and shows how they are used for the investigation of optical Feshbach resonances, the study of degenerate gases loaded into an optical lattice, as well as the coherent creation of Sr2 molecules.

Stellmer, Simon; Schreck, Florian; Killian, Thomas C.

2014-03-01

189

Different Fuels and Greenhouse gases  

NSDL National Science Digital Library

In this video, Peter Hall (a senior scientist in the field of bioenergy research at Crown Research Institute Scion) describes how different products (e.g. coal, wood) produce differing amounts of greenhouse gases.

Waikato, The U.; Hub, Science L.

190

MRI using hyperpolarized noble gases  

Microsoft Academic Search

.   The aim of this study was to review the physical basis of MRI using hyperpolarized noble gases as well as the present status\\u000a of preclinical and clinical applications. Non-radioactive noble gases with a nuclear spin 1\\/2 (He-3, Xe-129) can be hyperpolarized\\u000a by optical pumping. Polarization is transferred from circularly polarized laser light to the noble-gas atoms via alkali-metal\\u000a vapors

H.-U. Kauczor; R. Surkau; T. Roberts

1998-01-01

191

Unreleased Energy in Flame Gases  

Microsoft Academic Search

WE recently reported1 the results of temperature measurements made by means of very fine quartz-coated platinum wires in the flame gases resulting from the combustion of hydrocarbon-air mixtures in a specially constructed burner. From these measurements estimates were made of the proportion of the heat of combustion which was unreleased in the flame gases for the purpose of increasing their

W. T. David; J. Mann

1944-01-01

192

THE IMPORTANCE OF PHYSICAL MODELS FOR DERIVING DUST MASSES AND GRAIN SIZE DISTRIBUTIONS IN SUPERNOVA EJECTA. I. RADIATIVELY HEATED DUST IN THE CRAB NEBULA  

SciTech Connect

Recent far-infrared (IR) observations of supernova remnants (SNRs) have revealed significantly large amounts of newly condensed dust in their ejecta, comparable to the total mass of available refractory elements. The dust masses derived from these observations assume that all the grains of a given species radiate at the same temperature, regardless of the dust heating mechanism or grain radius. In this paper, we derive the dust mass in the ejecta of the Crab Nebula, using a physical model for the heating and radiation from the dust. We adopt a power-law distribution of grain sizes and two different dust compositions (silicates and amorphous carbon), and calculate the heating rate of each dust grain by the radiation from the pulsar wind nebula. We find that the grains attain a continuous range of temperatures, depending on their size and composition. The total mass derived from the best-fit models to the observed IR spectrum is 0.019-0.13 M{sub Sun }, depending on the assumed grain composition. We find that the power-law size distribution of dust grains is characterized by a power-law index of 3.5-4.0 and a maximum grain size larger than 0.1 {mu}m. The grain sizes and composition are consistent with what is expected for dust grains formed in a Type IIP supernova (SN). Our derived dust mass is at least a factor of two less than the mass reported in previous studies of the Crab Nebula that assumed more simplified two-temperature models. These models also require a larger mass of refractory elements to be locked up in dust than was likely available in the ejecta. The results of this study show that a physical model resulting in a realistic distribution of dust temperatures can constrain the dust properties and affect the derived dust masses. Our study may also have important implications for deriving grain properties and mass estimates in other SNRs and for the ultimate question of whether SNe are major sources of dust in the Galactic interstellar medium and in external galaxies.

Temim, Tea; Dwek, Eli, E-mail: tea.temim@nasa.gov [Observational Cosmology Lab, Code 665, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

2013-09-01

193

Importance of Dissolved Organic Carbon Optical Properties, Iron, and Ultraviolet Radiation for the Production of Dissolved Gaseous Mercury in Freshwater Systems  

NASA Astrophysics Data System (ADS)

The emission of dissolved gaseous mercury (DGM) from water surfaces into the atmosphere is an important process because it removes mercury from aquatic systems, where it might otherwise be available for methylation and bioaccumulation. One of the most important factors that contributes to the production and emission of DGM from aquatic systems is interaction with ultraviolet radiation (UVR). Irradiation of aqueous mercury by UVR can directly cause both photooxidation, which may reduce mercury emissions from water surfaces, and photoreduction, which may increase emission. Numerous studies have demonstrated that dissolved organic carbon (DOC) also plays an important role in the cycling of mercury through both binding and photoreactions. The strength of the Hg-DOC interaction is dependent, in part, on DOC characteristics, which can be evaluated using optical techniques such as absorbance and fluorescence. These two optical properties of DOC vary as a function of DOC source or the degree of oxidation and can therefore be used as a proxy for chemical characteristics (aromatic content, etc.). Additionally, iron plays a role in the photoreactivity of DOC and absorption of UVR in freshwater systems, and may therefore be important in DGM production. This study assesses the effects of UVR, DOC optical characteristics, and iron on the formation of DGM using controlled laboratory experiments in a 2 x 2 x 2 matrix. A DOC solution (8 mg C/L) and deionized water were each spiked with mercury to achieve a minimum concentration of 50 ng/L and allowed to equilibrate in the dark for 24 hours. Iron was added to half the sample vials (10 uMol/L), and samples were incubated in both light (UVR) and dark conditions for 6 hours at room temperature (25 C). DGM and total dissolved mercury were measured at the beginning and end of the exposures using double-focusing gold trap amalgamation and atomic fluorescence spectroscopy, and concentrations were compared between treatments. The initial DOC solution was then photooxidized using UVR to alter its optical properties (fluorescence ratio, spectral slope, SUVA), and the experiment was repeated to asses the effect of DOC chemical characteristics on DGM production. Initial results are promising and suggest that both iron and DOC influence the amount of DGM formed in solution. Further replication and data analysis are required to completely understand the results of this experiment. The results of this experiment will help elucidate controls on DGM production in freshwater systems, and may identify DOC optical properties that would be useful to monitor in conjunction with field mercury emission measurements in aquatic environments.

Wollenberg, J. L.; Peters, S. C.

2006-12-01

194

EDITORIAL: Cold Quantum GasesEditorial: Cold Quantum Gases  

NASA Astrophysics Data System (ADS)

This Special Issue of Journal of Optics B: Quantum and Semiclassical Optics brings together the contributions of various researchers working on theoretical and experimental aspects of cold quantum gases. Different aspects of atom optics, matter wave interferometry, laser manipulation of atoms and molecules, and production of very cold and degenerate gases are presented. The variety of subjects demonstrates the steadily expanding role associated with this research area. The topics discussed in this issue, extending from basic physics to applications of atom optics and of cold atomic samples, include: bulletBose--Einstein condensation bulletFermi degenerate gases bulletCharacterization and manipulation of quantum gases bulletCoherent and nonlinear cold matter wave optics bulletNew schemes for laser cooling bulletCoherent cold molecular gases bulletUltra-precise atomic clocks bulletApplications of cold quantum gases to metrology and spectroscopy bulletApplications of cold quantum gases to quantum computing bulletNanoprobes and nanolithography. This special issue is published in connection with the 7th International Workshop on Atom Optics and Interferometry, held in Lunteren, The Netherlands, from 28 September to 2 October 2002. This was the last in a series of Workshops organized with the support of the European Community that have greatly contributed to progress in this area. The scientific part of the Workshop was managed by A Hemmerich, W Hogervorst, W Vassen and J T M Walraven, with input from members of the International Programme Committee who are listed below. The practical aspects of the organization were ably handled by Petra de Gijsel from the Vrije Universiteit in Amsterdam. The Workshop was funded by the European Science Foundation (programme BEC2000+), the European Networks 'Cold Quantum Gases (CQG)', coordinated by E Arimondo, and 'Cold Atoms and Ultraprecise Atomic Clocks (CAUAC)', coordinated by J Henningsen, by the German Physical Society (DFG), by the Dutch Foundation for Fundamental Research on Matter (FOM) and by the Dutch Gelderland province. We thank all these sponsors and the members of the International Programme Committee for making the Workshop such a success. At this point we take the opportunity to express our gratitude to both authors and reviewers, for their efforts in preparing and ensuring the high quality of the papers in this special issue. Wim Vassen Vrije Universiteit, Amsterdam Andreas Hemmerich Universität Hamburg Ennio Arimondo Università di Pisa Guest Editors International Programme Committee A Aspect Orsay, France E Cornell Boulder, USA W Ertmer Hannover, Germany T W Haensch Munich, Germany A Hemmerich Hamburg, Germany W Hogervorst Amsterdam, The Netherlands D Kleppner Cambridge, USA C Salomon Paris, France G V Shlyapnikov Amsterdam, Paris, Moscow S Stringari Trento, Italy W Vassen Amsterdam, The Netherlands J T M Walraven Amsterdam, The Netherlands

Vassen, W.; Hemmerich, A.; Arimondo, E.

2003-04-01

195

The emission of biogenic sulphur gases from incubated Chinese paddy soil and its relationship with carbon dioxide  

Microsoft Academic Search

Biogeic sulphur gases emitted from terrestrial ecosystem may play an important role in the global sulphur cycle and have a profound influence on global climate change. In this paper, the emissions of volatile sulphur gases and carbon dioxide from incubated paddy soil were measured. The paddy soils were collected from Nanjing and Yangzhou, China. Six species of sulphur?containing gases were

Zhen Yang; Li Kong; Shiming Wang

1997-01-01

196

The strange gases of Jupiter and Saturn  

SciTech Connect

The various gases found in the atmospheres of Jupiter and Saturn are discussed. A history of scientific investigation of these planets is outlined and results of these discoveries are considered. The molecular species found in these two planets are classified into several groups. The first group consists of H{sub 2}, He, CH{sub 4}, NH{sub 3}, and H{sub 2}O while the second group contains gases formed as the chemical byproducts of solar radiation, including simple hydrocarbons such as C{sub 2}H{sub 2} and C{sub 2}H{sub 6} and charged particles such as H{sub 3}{sup +}. The last group contains compounds which are chemically unstable in parts of Jupiter's atmosphere that have been probed and include Ge and As; two elements usually found in minerals on earth. An investigation of origin of these elements which are currently part of the upper reaches of the atmosphere of Jupiter and Saturn has led to discoveries about much deeper and hotter parts of atmospheres that can never be observed directly. A number of hypotheses are presented to account for the presence of various unexpected compounds, such as carbon monoxide.

Noll, K.S. (NASA, Huntsville, AL (USA))

1990-12-01

197

Strongly Interacting Degenerate Fermi Gases  

NASA Astrophysics Data System (ADS)

Experimental methods of laser and evaporative cooling, used in the production of atomic Bose-Einstein condensates, have recently been extended to realize quantum degeneracy in trapped Fermi gases. Fermi gases are a rich new system to study the interplay between quantum statistics and atomic interactions, with the ultimate goal being the achievement of different regimes of fermionic superfluidity. We have created large samples of degenerate fermionic lithium and prepared suitable conditions of spin composition and magnetic field to probe a regime of strong interactions in the vicinity of a Feshbach Resonance. Experimental results from these investigations will be reported and discussed.

Gupta, Subhadeep

2003-05-01

198

Noble Gases in Sea Water.  

PubMed

Concentrations of noble gases in samples of sea water obtained at depths to 3437 meters from a Pacific Ocean station were measured by mass spectrometry. An excess of helium, in relation to concentrations of the other noble gases, is attributed to influx of atoms of this gas from the sediments where it is produced by the natural radioactive decay of members of the uranium and thorium series. On the basis of a steady-state model, the escape of helium from the earth is calculated at 6.4 x 10(13) atoms per square centimeter per year. PMID:17832398

Bieri, R; Koide, M; Goldberg, E D

1964-11-20

199

Greenhouse Gases Observation From TANSO on GOSAT  

NASA Astrophysics Data System (ADS)

The Greenhouse gases Observing SATellite (GOSAT) is a satellite to monitor the carbon dioxide (CO2) and the methane (CH4) globally from orbit. Thermal And Near infrared Sensor for carbon Observation Fourier- Transform Spectrometer (TANSO-FTS) detects the Short wave infrared (SWIR) reflected on the earth's surface as well as the thermal infrared (TIR) radiated from the ground and the atmosphere. TANSO-FTS is capable of detecting wide spectral coverage, specifically, three narrow bands (0.76, 1.6, and 2 micron) and a wide band (5.5-14.3 micron) with 0.2 cm-1 spectral resolution. TANSO Cloud and Aerosol Imager (TANSO-CAI) is a radiometer of ultraviolet (UV), visible, and SWIR to correct cloud and aerosol interference. The paper presents the instrument design and performance ground test results; as well as, pre-launch and onboard calibration schemes.

Kuze, A.; Suto, H.; Kaneko, Y.; Hamazaki, T.

2006-12-01

200

On flame kernel formation and propagation in premixed gases  

SciTech Connect

Flame kernel formation and propagation in premixed gases have been studied experimentally and theoretically. The experiments have been carried out at constant pressure and temperature in a constant volume vessel located in a high speed shadowgraph system. The formation and propagation of the hot plasma kernel has been simulated for inert gas mixtures using a thermodynamic model. The effects of various parameters including the discharge energy, radiation losses, initial temperature and initial volume of the plasma have been studied in detail. The experiments have been extended to flame kernel formation and propagation of methane/air mixtures. The effect of energy terms including spark energy, chemical energy and energy losses on flame kernel formation and propagation have been investigated. The inputs for this model are the initial conditions of the mixture and experimental data for flame radii. It is concluded that these are the most important parameters effecting plasma kernel growth. The results of laminar burning speeds have been compared with previously published results and are in good agreement. (author)

Eisazadeh-Far, Kian; Metghalchi, Hameed [Northeastern University, Mechanical and Industrial Engineering Department, Boston, MA 02115 (United States); Parsinejad, Farzan [Chevron Oronite Company LLC, Richmond, CA 94801 (United States); Keck, James C. [Massachusetts Institute of Technology, Cambridge, MA 02139 (United States)

2010-12-15

201

Interaction quenches of Fermi gases  

SciTech Connect

It is shown that the jump in the momentum distribution of Fermi gases evolves smoothly for small and intermediate times once an interaction between the fermions is suddenly switched on. The jump does not vanish abruptly. The loci in momentum space where the jumps occur are those of the noninteracting Fermi sea. No relaxation of the Fermi surface geometry takes place.

Uhrig, Goetz S. [Lehrstuhl fuer Theoretische Physik I, Technische Universitaet Dortmund, Otto-Hahn Strasse 4, D-44221 Dortmund (Germany)

2009-12-15

202

Effects of Solar Radiation on the Optical Quality of Dissolved Organic Material in a Tidal Marsh Estuarine Ecosystem  

Microsoft Academic Search

Photochemical alteration of colored dissolved organic matter (CDOM) during exposure to solar UV and Visible radiation generates a variety of photoproducts, including reactive oxygen species, atmospherically important trace gases, and microbially labile carbonyl compounds. Sunlight-induced changes in CDOM chemical structure are reflected in changes of its optical properties that provide a first order measure of the photoreactivity of CDOM in

M. Tzortziou; P. J. Neale; C. L. Osburn; J. R. Herman

2007-01-01

203

IMG, interferometric measurement of greenhouse gases from space  

Microsoft Academic Search

A Michelson interferometer is under development as a payload of the ADEOS satellite. It will measure the spectra of terrestrial thermal infrared radiation with a nadir view in 700-3,000 cm-1 wavenumber region with an apodized resolution of 0.1 cm-1. Using those measured spectra, we will retrieve the altitude profiles of atmospheric temperature and the concentrations of greenhouse gases such as

T. Ogawa; H. Shimoda; M. Hayashi; R. Imasu; A. Ono; S. Nishinomiya; H. Kobayashi

1994-01-01

204

High order harmonic generation in rare gases  

SciTech Connect

The process of high order harmonic generation in atomic gases has shown great promise as a method of generating extremely short wavelength radiation, extending far into the extreme ultraviolet (XUV). The process is conceptually simple. A very intense laser pulse (I {approximately}10{sup 13}-10{sup 14} W/cm{sup 2}) is focused into a dense ({approximately}10{sup l7} particles/cm{sup 3}) atomic medium, causing the atoms to become polarized. These atomic dipoles are then coherently driven by the laser field and begin to radiate at odd harmonics of the laser field. This dissertation is a study of both the physical mechanism of harmonic generation as well as its development as a source of coherent XUV radiation. Recently, a semiclassical theory has been proposed which provides a simple, intuitive description of harmonic generation. In this picture the process is treated in two steps. The atom ionizes via tunneling after which its classical motion in the laser field is studied. Electron trajectories which return to the vicinity of the nucleus may recombine and emit a harmonic photon, while those which do not return will ionize. An experiment was performed to test the validity of this model wherein the trajectory of the electron as it orbits the nucleus or ion core is perturbed by driving the process with elliptically, rather than linearly, polarized laser radiation. The semiclassical theory predicts a rapid turn-off of harmonic production as the ellipticity of the driving field is increased. This decrease in harmonic production is observed experimentally and a simple quantum mechanical theory is used to model the data. The second major focus of this work was on development of the harmonic {open_quotes}source{close_quotes}. A series of experiments were performed examining the spatial profiles of the harmonics. The quality of the spatial profile is crucial if the harmonics are to be used as the source for experiments, particularly if they must be refocused.

Budil, K.S.

1994-05-01

205

40 CFR 92.112 - Analytical gases.  

Code of Federal Regulations, 2010 CFR

...nitrogen and oxygen with oxygen concentrations between... (2) Calibration gases shall be accurate to within...gas standards, or other gas standards which have been...Administrator. (i) Oxygen interference check gases shall contain...

2010-07-01

206

Radiation Laws  

NSDL National Science Digital Library

This site lists physical laws that describe radiation. Topics covered include the Plank Radiation Law, and the Wien and Stefan-Boltzmann Laws. The site also features a table summarizing the blackbody temperatures necessary to give a peak for emitted radiation in various regions of the spectrum, and three Java applets illustrating important properties of blackbody radiation.

Astronomy, Department O.; Knoxville, University O.

207

Nitrogen to argon ratio in volcanic gases  

Microsoft Academic Search

A study is made of N2\\/Ar ratios in volcanic gases in order to evaluate the factors influencing such ratios. Particular attention is given to N2 derived from sedimentary material as it influences the N2\\/Ar ratio of volcanic gases. Gases derived from the deeper mantle of the earth are also examined for N2\\/Ar ratios. The N2\\/Ar ratios of volcanic gases show

S. Matsuo; M. Suzuki; Y. Mizutani

1978-01-01

208

Climate Policy with Multiple Sources and Sinks of Greenhouse Gases  

Microsoft Academic Search

This paper studies how inclusion of many sources, sinks and reservoirs -- a comprehensive approach -- affects climate policy, compared with a control merely of CO2. Two questions of particular importance arise in such an analysis. One is how to aggregate the emissions of different climate gases, and the other is how to include all relevant measures in the analysis.

H. Asbjørn Aaheim

1999-01-01

209

(Seminar on anthropogenic emissions of greenhouse gases)  

Microsoft Academic Search

The traveler participated in an Organization for Economic Cooperation and Development (OECD) expert seminar on anthropogenic emissions of greenhouse gases. The meeting was initiated by OECD in anticipation of the need for national estimating emissions of greenhouse gases which will precede an international convention on greenhouse gases. The meeting which attracted delegates from 44 countries, began the process of developing

Marland

1991-01-01

210

Failure of activated charcoal to reduce the release of gases produced by the colonic flora  

Microsoft Academic Search

Objective: Activated charcoal is used to treat excessive volume or malodor of intestinal gas. Our previous studies demonstrated that activated charcoal failed to bind appreciable quantities of the volumetrically important gut gases. However, the odor of feces and flatus derives primarily from trace quantities of sulfur-containing gases, primarily H2S and methanethiol, which should avidly bind to activated charcoal. The goal

Fabrizis L Suarez; Julie Furne; John Springfield; Michael D Levitt

1999-01-01

211

Annihilation in Gases and Galaxies  

NASA Technical Reports Server (NTRS)

This publication contains most of the papers, both invited and contributed, that were presented at the Workshop of Annihilation in Gases and Galaxies. This was the fifth in a biennial series associated with the International Conference on the Physics of Electronic and Atomic Collisions. Subjects covered included the scattering and annihilation of positrons and positronium atoms in various media, including those of astrophysical interest. In addition, the topics of antimatter and dark matter were covered.

Drachman, Richard J. (editor)

1990-01-01

212

Atmospheric Chemistry and Greenhouse Gases  

SciTech Connect

Chapter 4 of the IPCC Third Assessment Report Climate Change 2001: The Scientific Basis. Sections include: Executive Summary 2414.1 Introduction 2434.2 Trace Gases: Current Observations, Trends and Budgets 2484.3 Projections of Future Emissions 2664.4 Projections of Atmospheric Composition for the 21st Century 2674.5 Open Questions 2774.6 Overall Impact of Global Atmospheric Chemistry Change 279

Ehhalt, D.; Prather, M.; Dentener, F.; Derwent, R.; Dlugokencky, Edward J.; Holland, E.; Isaksen, I.; Katima, J.; Kirchhoff, V.; Matson, P.; Midgley, P.; Wang, M.; Berntsen, T.; Bey, I.; Brasseur, G.; Buja, L.; Collins, W. J.; Daniel, J. S.; DeMore, W. B.; Derek, N.; Dickerson, R.; Etheridge, D.; Feichter, J.; Fraser, P.; Friedl, R.; Fuglestvedt, J.; Gauss, M.; Grenfell, L.; Grubler, Arnulf; Harris, N.; Hauglustaine, D.; Horowitz, L.; Jackman, C.; Jacob, D.; Jaegle, L.; Jain, Atul K.; Kanakidou, M.; Karlsdottir, S.; Ko, M.; Kurylo, M.; Lawrence, M.; Logan, J. A.; Manning, M.; Mauzerall, D.; McConnell, J.; Mickley, L. J.; Montzka, S.; Muller, J. F.; Olivier, J.; Pickering, K.; Pitari, G.; Roelofs, G.-J.; Rogers, H.; Rognerud, B.; Smith, Steven J.; Solomon, S.; Staehelin, J.; Steele, P.; Stevenson, D. S.; Sundet, J.; Thompson, A.; van Weele, M.; von Kuhlmann, R.; Wang, Y.; Weisenstein, D. K.; Wigley, T. M.; Wild, O.; Wuebbles, D.J.; Yantosca, R.; Joos, Fortunat; McFarland, M.

2001-10-01

213

Hot and Cold Ideal Gases  

NSDL National Science Digital Library

The EJS Hot and Cold Ideal Gases model simulates the mixing of hot and cold two-dimensional ideal gases in a square box. This simulation can be used as part of the activity described in "The Statistical Interpretation of Entropy: An Activity" by Todd Timberlake, to be published in The Physics Teacher. In the model, one gas is initially confined to the left side of the box while the other gas is confined to the right side. An animation window shows the motion of the particles in the box, while an optional graph window plots the temperature of each side of the box, which is determined by measuring the average KE of the particles on each side. The initial number of particles and temperature on each side of the square can be changed and a button allows the user to reverse the particle velocities at any time. The user can modify this simulation if EJS is installed locally by right-clicking within the plot and selecting "Open Ejs Model" from the pop-up menu item. EJS Hot and Cold Ideal Gases model was created using the Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_entropy_HotAndColdIdealGases.jar file will run the program if Java is installed. EJS is a part of the Open Source Physics Project and is designed to make it easier to access, modify, and generate computer models. Additional EJS models are available. They can be found by searching ComPADRE for Open Source Physics, OSP, or EJS.

Timberlake, Todd

2010-07-01

214

Condensation process for separating air pollutants from waste gases, and specifically from flue gases  

Microsoft Academic Search

A condensation process for separation of air pollutants from waste gases and, specifically, from flue gases. Sulfurous components of the waste gases in particular, but also heavy metals contained therein, can be separated at a very high degree of separation by fractional condensation when certain parameters are followed. The energy withdrawn from the waste gases during condensation is available as

Faatz

1984-01-01

215

Radiative interactions in nonequilibrium flows  

NASA Technical Reports Server (NTRS)

The influence of vibrational and chemical nonequilibrium upon infrared radiative energy transfer in nonisothermal gases is investigated. Essential information is provided on rate equations, relaxation times, transfer equations, band absorption, and radiative flux equations. The methodology developed is applied to three specific cases. These are, absorbing-emitting species between isothermal parallel plates, radiating gases in the earth's atmosphere, and supersonic flow of premixed hydrogen and air in an expanding nozzle. The results obtained for different cases reveal that the extent of radiative interactions is reduced significantly under nonequilibrium conditions. The method developed can be easily extended to investigate radiative interactions in complex nonequilibrium flows.

Tiwari, S. N.; Chandrasekhar, R.

1992-01-01

216

Geostationary earth radiation budget  

NASA Astrophysics Data System (ADS)

The Earth Radiation Budget (ERB), the balance between the incoming solar radiation from the sun and the outgoing reflected and scattered solar radiation and the thermal infrared emission from the Earth, provides information on the fundamental energy source of the climate system. To fulfil global coverage and sampling requirements, the ERB measurements have to be made from space. Broad-band measurements are necessary because all spectral regions in both the solar and infrared contribute to the radiative fluxes. Satellite data are used in a wide range of basic studies of the radiative forcing of the climate, such as understanding the effects of variations in trace gases, clouds and the surface. They also provide essential validation for climate models. All such measurements to date have been made from satellites in low earth orbit (LEO). There are strong diurnal variations in the radiation budget, particularly over land, in response to the diurnal variation of solar heating. Four LEO satellites could provide coverage of the diurnal cycle with a temporal resolution of 3 hours. At least hourly measurements are needed to resolve the diurnal cycle of tropical convection properly, and no practicable system of polar orbiting or other LEO satellites can deliver this. From the above, it appears that the only viable solution to the problem of diurnal sampling of the Earth's radiation budget is the inclusion of suitable sensors on the geostationary satellites which would allow for an essentially perfect temporal sampling. Disadvantages include the fact that geostationary satellites are much further from the Earth than polar orbiters, which affects the instrumental design, and each one can only provide a limited coverage of the globe. The Geostationary Earth Radiation Budget instrument (GERB) is a highly accurate visible-infrared radiometer designed to make unique measurements of the outgoing shortwave and longwave components of the Earth's Radiation Budget (ERB) from geostationary orbit. Such measurements have not been achieved previously, and are extremely important, because they will permit a rigorous test of our understanding of the diurnal variations in the ERB: this will enable improved operational weather monitoring and permit further important developments in climate change research. GERB will be launched on the (MSG) geostationary satellite in the year 2000. Both short-wave (0.32 - 4 micrometer) and total (0.32 - 30 micrometer) radiance measurements would be made, with longwave (4 - 30 micrometer) data obtained by subtraction. The accuracy requirements (1% short-wave and 0.5% longwave) are consistent with previous radiation budget measurements. The availability of GERB on MSG will also allow a more accurate calibration of the principal Meteosat Second Generation (MSG) operational sounding instrument, SEVIRI (Spinning, Enhanced Visible and InfraRed Imager).

Mossavati, Ruzbeh; Kellock, Steve; Mueller, Johannes; Harries, J. E.; Murray, J. E.; Sawyer, Eric C.; Caldwell, Martin E.; Oliver, M.; Delderfield, J.; Sandford, Michael C.

1997-12-01

217

The Kyoto Protocol and non-CO 2 Greenhouse Gases and Carbon Sinks  

Microsoft Academic Search

Many trace constituents other than carbon dioxide affect the radiative budget of the atmosphere. The existing international agreement to limit greenhouse gases, the Kyoto Protocol, includes carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), sulfur hexafluoride (SF6) and credit for some carbon sinks. We investigate technological options for reducing emissions of these gases and the economic

J. Reilly; M. Mayer; J. Harnisch

2002-01-01

218

Accounting for carbon cycle feedbacks in a comparison of the global warming effects of greenhouse gases  

Microsoft Academic Search

Greenhouse gases other than CO2 make a significant contribution to human-induced climate change, and multi-gas mitigation strategies are cheaper to implement than those which limit CO2 emissions alone. Most practical multi-gas mitigation strategies require metrics to relate the climate warming effects of CO2 and other greenhouse gases. Global warming potential (GWP), defined as the ratio of time-integrated radiative forcing of

Nathan P. Gillett; H. Damon Matthews

2010-01-01

219

Effective nonlinear GaSe crystal. Optical properties and applications  

NASA Astrophysics Data System (ADS)

We present an overview of the current state of the literature and research performed by the authors of the present paper on the experimental and theoretical results on the structural-, optical-, nonlinear optical (NLO)-properties (including two-photon absorption (TPA) and the terahertz (THz) range of spectra) and practical applications of a highly anisotropic Gallium Selenide (GaSe) semiconductor with emphasis on the ?-GaSe. Physical properties of ?-GaSe are important to researchers and designers developing different devices by using this material. This crystal possesses an outstanding NLO properties: high optical birefringence ? n ˜ 0.3 at 700 nm; high transparency range (0.7-18.0 ?m) with low absorption coefficient (? ? 0.3 cm-1); very high nonlinear susceptibility ?(2) ( d 22 ? 86 ± 17 pm/V, corresponding to (2.0 ± 0.4) × 10-7 esu) that is used for phase matched second harmonic generation (SHG) in a wide transparency range; high power threshold for optical damage; possibility to perform optical frequency conversion under phase-matching conditions in the near- to mid-IR and THz range of spectra, etc. The domain structure of crystal in connection with the NLO properties is discussed as studied by confocal Raman microscopy experiments. Perspectives for future research of GaSe are considered in the present article, which does not pretend to be one reflecting all existing papers on GaSe crystal and discussed subjects.

Allakhverdiev, K. R.; Yetis, M. Ö.; Özbek, S.; Baykara, T. K.; Salaev, E. Yu.

2009-05-01

220

Inert gases in Sea of Fertility regolith  

NASA Technical Reports Server (NTRS)

The content and isotopic composition were studied of inert gases -- He, Ne, Ar, Kr, and Xe -- in samples of lunar regolith returned by the Luna 16 automatic station. The samples were taken from depths of about 12 and 30 cm. The high concentrations of inert gases exceed by several orders their concentrations observed in ordinary stony meteorites. The gases in lunar regolith were a complex mixture of gases of different origins: Solar, cosmogenic, radiogenic, and so on. Solar wind gases predominated, distributed in the thin surficial layer of the regolith grains. The concentrations of these gases in the surficial layer is several cubic centimeters per gram. The isotopic composition of the inert gases of solar origin approaches their composition measured in gas-rich meteorites.

Vinogradov, A. P.; Zadorozhnyy, I. K.

1974-01-01

221

Effect of vincristine or bleomycin on radiation-induced cell killing of mice spermatogonial stem cells: The importance of sequence and time interval  

SciTech Connect

The effect of single doses of vincristine (VCR) or bleomycin (BLM) on mice spermatogonia was investigated, and the influence of either of these drugs on the radiation response of murine spermatogonial stem cells was examined. When assessed by flow cytometry, VCR (1.0 mg/kg) or BLM (100 mg/kg) reduced the survival in the differentiated spermatogonia to 4% and 37% of controls, respectively (p less than 0.05). VCR reduced the stem cells to 79% of controls (p less than 0.05), whereas BLM had no apparent effect on the stem cells (p greater than 0.05). Drugs were administered intraperitoneally up to 28 days before or after local irradiation with 9 Gy. VCR produced significant enhancement of radiation-induced damage to spermatogonial stem cells, which was most prominent when administered 6 or 12 hr after irradiation. BLM administered before irradiation or 1 hr after radiotherapy produced significant enhancement.

Hansen, P.V.; Sorensen, D. (Danish Cancer Society, Aarhus (Denmark))

1991-02-01

222

Connecting Soluble Trace Gases and Aerosol Vertical Distributions to Storm Properties  

NASA Astrophysics Data System (ADS)

Wet deposition is important because it removes soluble trace gases and aerosols from the atmosphere, thereby affecting ozone photochemistry, visibility, and potentially the radiation budget of the atmosphere. Wet deposition of chemical constituents not only depends on the solubility of the compound, but also on the storm properties, such as liquid and ice water contents, precipitation production and evaporation, and the ice-to-water partitioning. These storm properties, in turn, depend on the storm dynamics and its thermodynamic environment. We analyze the Deep Convective Clouds and Chemistry (DC3) observations to connect the aircraft measurements of a range of soluble gases (e.g. HNO3, H2O2, HCHO, CH3OOH) to the storm and environment observations. These observations include aircraft measurements of water content, radar reflectivity (including hydrometeor structure), radar vertical velocities, and pre-storm soundings of convective available potential energy and wind shear. We use the 2-component mixture model to estimate scavenging and transport efficiencies. We then compare these efficiencies to various storm properties. Estimates of scavenging efficiencies vary substantially for HCHO (10-84%) for four different thunderstorms ranging from low shear, moderate CAPE to high shear, high CAPE environments. The preliminary scavenging efficiencies for H2O2 for the same four storms are estimated to be all >90%.

Barth, M. C.; Bela, M. M.; Applegate, M.; Fried, A.; Weibring, P.; Hanisco, T. F.; Arkinson, H. L.; Apel, E. C.; O'Sullivan, D. W.; Heikes, B.; Wennberg, P. O.; Crounse, J.; St Clair, J. M.; Nenes, A.; Markovic, M. Z.; Stith, J. L.; Campos, T. L.; Rutledge, S. A.; Basarab, B.; Fuchs, B.; Carey, L. D.; Bain, A. L.; Biggerstaff, M. I.; Wisthaler, A.; Diskin, G. S.; Campuzano Jost, P.; Ryerson, T. B.; Flocke, F. M.; Lance, S.

2013-12-01

223

Cold gases with anisotropic interactions  

NASA Astrophysics Data System (ADS)

A cold gas of particles with anisotropic interactions of a general form, due to a polarizing field, is studied. Special cases are atoms or molecules with dipole-dipole or quadrupole-quadrupole interactions. It is shown that the angular dependence of an observable on the direction of the polarizing field is largely determined by symmetry. For a gas in a confined quasi-two-dimensional geometry, the effective interaction is calculated in a general form. Some examples of dipole and quadrupole gases are considered. It is concluded that when anisotropic forces are studied in a general manner, one can obtain simpler results and better understanding for some problems.

Pikovski, Alexander

2014-03-01

224

Climate Change and Greenhouse Gases  

NASA Technical Reports Server (NTRS)

The American Geophysical Union (AGU), as a scientific organization devoted to research on the Earth and space sciences, provides current scientific information to the public on issues pertinent to geophysics. The Council of the AGU approved a position statement on Climate Change and Greenhouse Gases in December 1998. The statement, together with a short summary of the procedures that were followed in its preparation, review, and adoption were published in the February 2, 1999 issue of Eos ([AGU, 1999]. The present article reviews scientific understanding of this issue as presented in peer-reviewed publications that serves as the underlying basis of the position statement.

Ledley, Tamara S.; Sundquist, Eric; Schwartz, Stephen; Hall, Dorothy K.; Fellows, Jack; Killeen, Timothy

1999-01-01

225

Spark ignition of flowing gases  

NASA Technical Reports Server (NTRS)

Research conducted at the NACA Lewis Laboratory on ignition of flowing gases by means of long-duration discharges is summarized and analyzed. Data showing the effect of a flowing combustible mixture on the physical and electrical characteristics of spark discharges and data showing the effects of variables on the spark energy required for ignition that has been developed to predict the effect of many of the gas-stream and spark variables is described and applied to a limited amount of experimental data.

Swett, Clyde C , Jr

1956-01-01

226

Radiative Heating Profiles for Tropical Cloud Regimes  

NASA Astrophysics Data System (ADS)

Radiative heating is important for its effects on atmospheric circulation and cloud evolution in addition to its central role in influencing the atmospheric temperature structure. The vertical distribution of radiative heating is determined by the vertical profile of gases such as water vapor, ozone and CO2 as well as by clouds. The Atmospheric Radiation Measurement (ARM) program operates sites around the world which provide measurements of surface radiative fluxes and various measurements of the atmospheric state that effect surface fluxes. Continuously operating millimeter cloud radars at each site provide the means to derive vertical profiles of cloud properties. In previous work, we have used these cloud profiles in combination with profiles of temperature and humidity from radiosondes to calculate radiative flux profiles using a 4-stream radiative transfer model at the three tropical ARM sites: Manus, Nauru, and Darwin. In the current study, we will use the vertical profiles of cloud properties at these sites to segregate the data into distinct cloud regimes. By compositing radiative heating profiles in different regimes, we will define characteristic radiative heating profiles of each cloud regime. Analysis of the data in terms of cloud regime provides datasets which can be more easily compared with climate model results.

Mather, J. H.; McFarlane, S. A.

2007-12-01

227

Greenhouse gases and recovery of the Earth's ozone layer  

NASA Astrophysics Data System (ADS)

A numerical two-dimension zonally average interactive dynamical radiative-photochemical model of the atmosphere is used for investigation the role of the greenhouse gases CO2, CH4, and N2O in the recovery of the Earth's ozone layer after reduction of anthropogenic discharges in the atmosphere of chlorine and bromine compounds. The model allows calculating self-consistently diabatic circulation, temperature, gaseous composition of the troposphere and stratosphere at latitudes from the South to North Poles, as well as distribution of sulphate aerosol particles and polar stratospheric clouds of types I and II. The scenarios of future changes of the greenhouse gases and chlorine and bromine species are taken from Climate Change 1995. The calculations show that expected cooling of the stratosphere caused by the increasing of the greenhouse gases, particularly CO2, enhances the ozone concentration in the stratosphere due to a weakness of the efficiencies of all catalytic cycles of the ozone destruction caused by temperature dependencies of photochemical reactions. The result of this effect is a significant acceleration of the ozone layer recovery after reduction of anthropogenic discharges in the atmosphere of chlorine and bromine species. On the other hand, the cooling of the stratosphere intensifies a formation of the polar stratospheric clouds in the lower stratosphere in the Polar Regions. Heterogeneous reactions on the polar stratospheric clouds, which are the key processes in the destruction of the ozone layer at the high latitudes, lead to more intensive ozone depletion here, which causes a delay of the ozone layer recovery. The calculations show that this effect is weaker than the first one so that the global ozone will recover faster under conditions of continuing anthropogenic growth of the greenhouse gases. The model predicts in this case that the annual average global ozone will reach its undisturbed level of 1980 by about 2040. If the growth of the greenhouse gases is stopped, the global ozone will reach this level only in the end of the 21st century.

Dyominov, I. G.; Zadorozhny, A. M.

228

The importance of limited exposure to ultraviolet radiation and dietary factors in the aetiology of Asian rickets: a risk-factor model.  

PubMed

Regional variation in the prevalence of Asian rickets was examined in Coventry, Bradford and Glasgow. Records of 152 weeks of daylight outdoor exposure were obtained from 104 Glasgow Asian children, 53 of whom had been treated for rickets. Records of seven-day weighed dietary intake were obtained from 84 Asian children, 43 of whom had been treated for rickets. There was a marked north-south gradient in the prevalence of Asian rickets. In all cases of severe rickets with deformity the child was vegetarian. Severe rickets was associated with lower intake of meat, higher intake of chapati and lower daylight outdoor exposure values than in normal children. Multivariate analysis employing a combination of these variables provided good separation between rachitic and normal groups. A risk-factor model is proposed which suggests that regional variation in the prevalence of rickets among Asian communities in Britain is mainly determined by the effects of latitude and the nature of the urban environment on available ultraviolet radiation. Where UV radiation is restricted, individual propensity to rickets within a given Asian community is mainly determined by dietary factors. PMID:3659260

Henderson, J B; Dunnigan, M G; McIntosh, W B; Abdul-Motaal, A A; Gettinby, G; Glekin, B M

1987-05-01

229

Imported malaria*  

PubMed Central

There have been 4 waves of imported malaria in the USA. They occurred during the colonization of the country and during the Second World War, the UN Police Action in Korea, and the Viet-Nam conflict. The first 3 episodes are briefly described and the data on imported malaria from Viet-Nam are discussed in detail. Endemic malaria is resurgent in many tropical countries and international travel is also on the rise. This increases the likelihood of malaria being imported from an endemic area and introduced into a receptive area. The best defence for countries threatened by imported malaria is a vigorous surveillance programme. The principles of surveillance are discussed and an example of their application is provided by a description of the methods used to conduct surveillance of malaria in the USA.

Schultz, Myron G.

1974-01-01

230

Predicting Flows of Rarefied Gases  

NASA Technical Reports Server (NTRS)

DSMC Analysis Code (DAC) is a flexible, highly automated, easy-to-use computer program for predicting flows of rarefied gases -- especially flows of upper-atmospheric, propulsion, and vented gases impinging on spacecraft surfaces. DAC implements the direct simulation Monte Carlo (DSMC) method, which is widely recognized as standard for simulating flows at densities so low that the continuum-based equations of computational fluid dynamics are invalid. DAC enables users to model complex surface shapes and boundary conditions quickly and easily. The discretization of a flow field into computational grids is automated, thereby relieving the user of a traditionally time-consuming task while ensuring (1) appropriate refinement of grids throughout the computational domain, (2) determination of optimal settings for temporal discretization and other simulation parameters, and (3) satisfaction of the fundamental constraints of the method. In so doing, DAC ensures an accurate and efficient simulation. In addition, DAC can utilize parallel processing to reduce computation time. The domain decomposition needed for parallel processing is completely automated, and the software employs a dynamic load-balancing mechanism to ensure optimal parallel efficiency throughout the simulation.

LeBeau, Gerald J.; Wilmoth, Richard G.

2005-01-01

231

Synchrotron radiation - Applications in the earth sciences  

NASA Technical Reports Server (NTRS)

Synchrotron-radiation sources and their characteristics are overviewed along with recent synchrotron-based research on earth materials and future earth-science applications utilizing the next generation of synchrotron-radiation sources presently under construction. Focus is placed on X-ray scattering studies of earth materials (crystalline and noncrystalline) under ambient conditions, diffraction studies of earth materials at high pressures and/or temperatures, spectroscopic studies, primarily X-ray absorption spectroscopy, and spatially resolved X-ray fluorescence studies of compositional variations in earth materials. It is noted that other synchrotron-based methods, such as X-ray tomography and topography may become important in characterizing earth materials, while soft X-ray/vacuum ultraviolet radiation from synchrotron sources can be applied to problems involving the structural environments of low-atomic-number elements and the characterization of surface reactions of minerals with liquids and gases.

Bassett, W. A.; Brown, G. E., Jr.

1990-01-01

232

Method for treating combustion exhaust gases  

SciTech Connect

A method for treating exhaust gases generated by incinerating industrial wastes in a combustion chamber leading to a reaction chamber is described, comprising the steps of: (a) introducing the exhaust gases from the combustion chamber to the reaction chamber while keeping a high temperature; (b) spraying the exhaust gases flowing through the reaction chamber with water to vaporize the water with the heat of the exhaust gases, reducing the temperature of the exhaust gases while forming a saturated aqueous vapor of microparticles in intimate contact with noxious materials of the exhaust gases, thereby permitting the vapor microparticles to absorb and collect the noxious materials of the exhaust graft to form an acidic, saturated aqueous vapor; (c) spraying the acidic, saturated aqueous vapor with a neutralizing agent in a primary neutralization chamber to at least substantially denature the acidic, saturated aqueous vapor to a neutralized waste liquid; and (d) collecting and evacuating the neutralized waste liquid.

Sato, Inomatsu.

1993-05-25

233

Dipolar Fermi gases in anisotropic traps  

SciTech Connect

The quest for quantum degenerate Fermi gases interacting through the anisotropic and long-range dipole-dipole interaction is an exciting and fast developing branch within the cold-atom research program. Recent experimental progress in trapping, cooling, and controlling polar molecules with large electric dipole moments has, therefore, motivated much theoretical effort. In a recent letter, we have briefly discussed the application of a variational time-dependent Hartree-Fock approach to study theoretically both the static and the dynamic properties of such a system in a cylinder-symmetric harmonic trap. We focused on the hydrodynamic regime, where collisions ensure the equilibrium locally. Here we present a detailed theory extended to encompass the general case of a harmonic trap geometry without any symmetry. After deriving the equations of motion for the gas, we explore their static solutions to investigate key properties like the aspect ratios in both real and momentum space as well as the stability diagram. We find that, despite the lack of symmetry of the trap, the momentum distribution remains cylinder symmetric. The equations of motion are then used to study the low-lying hydrodynamic excitations, where, apart from the quadrupole and monopole modes, the radial quadrupole mode is also investigated. Furthermore, we study the time-of-flight dynamics as it represents an important diagnostic tool for quantum gases. We find that the real-space aspect ratios are inverted during the expansion, while that in momentum space becomes asymptotically unity. In addition, anisotropic features of the dipole-dipole interaction are discussed in detail. These results could be particularly useful for future investigations of strongly dipolar heteronuclear polar molecules deep in the quantum degenerate regime.

Lima, Aristeu R. P.; Pelster, Axel [Institut fuer Theoretische Physik, Freie Universitaet Berlin, Arnimallee 14, D-14195 Berlin (Germany); Fachbereich Physik, Universitaet Duisburg-Essen, Lotharstrasse 1, D-47048 Duisburg, Germany and Institut fuer Physik und Astronomie, Potsdam Universitaet, Karl-Liebknecht-Strasse 24, D-14476 Potsdam (Germany)

2010-06-15

234

46 CFR 194.15-17 - Compressed gases other than inert gases.  

Code of Federal Regulations, 2013 CFR

...CONTINUED) OCEANOGRAPHIC RESEARCH VESSELS HANDLING, USE, AND CONTROL OF EXPLOSIVES AND OTHER HAZARDOUS MATERIALS Chemistry Laboratory and Scientific Laboratory § 194.15-17 Compressed gases other than inert gases. (a)...

2013-10-01

235

Continuous Processing with Mars Gases  

NASA Technical Reports Server (NTRS)

Current Martian missions call for the production of oxygen for breathing, and fuel and oxygen for propulsion to be produced from atmospheric carbon dioxide (CO2). Adsorption and freezing are the two methods considered for capturing CO, from the atmosphere. However, the nitrogen (N2) and argon (Ar), which make up less than 5 percent of the atmosphere, cause difficulties with both of these processes by blocking the CO2, This results in the capture process rapidly changing from a pressure driven process to a diffusion controlled process. To increase the CO, capture rates, some type of mechanical pump is usually proposed to remove the N2 and Ar. The N2 and Ar are useful and have been proposed for blanketing and pressurizing fuel tanks and as buffer gas for breathing air for manned missions. Separation of the Martian gases with the required purity can be accomplished with a combination of membranes. These membrane systems do not require a high feed pressure and provide suitable separation. Therefore, by use of the appropriate membrane combination with the Martian atmosphere supplied by a compressor a continuous supply of CO2 for fuel and oxygen production can be supplied. This phase of our program has focused on the selection of the membrane system. Since permeation data for membranes did not exist for Martian atmospheric pressures and temperatures, this information had to be compiled. The general trend as the temperature was lowered was for the membranes to become more selective. In addition, the relative permeation rates between the three gases changed with temperature. The end result was to provide design parameters that could be used to separate CO2 from N2 and Ar. This paper will present the membrane data, provide the design requirements for a compressor, and compare the results with adsorption and freezer methods.

Parrish, Clyde; Jennings, Paul; Delgado, Hugo (Technical Monitor)

2001-01-01

236

Continuous Processing With Mars Gases  

NASA Astrophysics Data System (ADS)

Current Martian missions call for the production of oxygen for breathing, and fuel and oxygen for propulsion to be produced from atmospheric carbon dioxide (CO2). Adsorption and freezing are the two methods considered for capturing CO2 from the atmosphere. However, the nitrogen (N2) and argon (Ar), which make up less than 5 percent of the atmosphere, cause difficulties with both of these processes by blocking the CO2. This results in the capture process rapidly changing from a pressure driven process to a diffusion controlled process. To increase the CO2 capture rates, some type of mechanical pump is usually proposed to remove the N2 and Ar. The N2 and Ar are useful and have been proposed for blanketing and pressurizing fuel tanks and as buffer gas for breathing air for manned missions. Separation of the Martian gases with the required purity can be accomplished with a combination of membranes. These membrane systems do not require a high feed pressure and provide suitable separation. Therefore, by use of the appropriate membrane combination with the Martian atmosphere supplied by a compressor a continuous Supply Of CO2 for fuel and oxygen production can be supplied. This phase of our program has focused on the selection of the membrane system. Since permeation data for membranes did not exist for Martian atmospheric pressures and temperatures, this information had to be compiled. The general trend as the temperature was lowered was for the membranes to become more selective. In addition, the relative permeation rates between the three gases changed with temperature. The end result was to provide design parameters that could be used to separate CO2 from N2 and Ar. This paper will present the membrane data, provide the design requirements for a compressor, and compare the results with adsorption and freezer methods.

Parrish, Clyde; Jennings, Paul

2000-01-01

237

Geochemical characteristics of abiogenic alkane gases  

NASA Astrophysics Data System (ADS)

Recently abiogenic alkanes have been found in various locations in the world and other celestial bodies. The chemical composition of abiogenic alkane gases varies widely. The content of methane is low and nearly no C2+ is found in the abiogenic alkane gases from fluid inclusions in volcanic rocks or hot springs in China. In the unsedimented submarine hydrothermal vent system C1/C2+ ratios are much greater than those for the thermogenic gases, mostly >800 and in some cases up to 8,000. In the Songliao Basin, China, C1/C2+ of some abiogenic gases are often less than 150. Abiogenic alkane gases which have been found in nature often have carbon isotopic reversal among C1-C4 alkanes (?13C1>?13C2>?13C3>?13C4), whereas both regular and reversed hydrogen isotope distribution pattern among C1-C4 alkanes have been reported. The ?13C of abiogenic methane is mainly greater than -30° though laboratory synthesized methane can have ?13C as low as -57°, and its ?D1 values vary widely and overlap with biogenic gases. High 3He/4He ratios often indicate the addition of mantle-derived helium and are related to abiogenic gases. However, some biogenic gases can also have high 3He/4He ratios up to 8. The CH4/3He end-member is often lower than 106 for abiogenic alkane gases while greater than 10^13 for biogenic gases, and the values between these two end-members often reflect the mixing of biogenic and abiogenic gases.

Ni, Y.; Dai, J.

2009-12-01

238

Origin of the atmospheric noble gases in OIB and MORB  

NASA Astrophysics Data System (ADS)

In order to constrain the origin of atmospheric noble gases measured in glassy margins of pillow lava from both OIB and MORB, fresh glassy samples from pillow lavas erupted at 30-40 meters deep in 2004 and 2007 and sampled by a diver without seeing atmosphere at the Piton de la Fournaise volcano (Réunion island) were analyzed. These samples were chosen because of the low depth of eruption implying that the magmatic noble gases were strongly degassed. Step crushing, using the same analytical procedure that typical MORB and OIB samples, was performed. The sample doesn't show any magmatic helium implying that magmatic gases were indeed degased. However, important quantities of rare gases with air-like elementary abundances and isotopic ratios are observed during step crushing. These results suggest that this atmospheric component was injected in the sample during or after eruption. Our preferred explanation for the presence of air-like components in MORB and OIB is the presence of seawater, and sometimes air when exposed for a long time in the laboratory, in some vesicles or cracks, that can be degased under vacuum but not fast enough to avoid contamination of the magmatic component during gas extraction after 24-48h in vacuum.

Moreira, M. A.

2011-12-01

239

The gaseous explosive reaction : the effect of inert gases  

NASA Technical Reports Server (NTRS)

Attention is called in this report to previous investigations of gaseous explosive reactions carried out under constant volume conditions, where the effect of inert gases on the thermodynamic equilibrium was determined. The advantage of constant pressure methods over those of constant volume as applied to studies of the gaseous explosive reaction is pointed out and the possibility of realizing for this purpose a constant pressure bomb mentioned. The application of constant pressure methods to the study of gaseous explosive reactions, made possible by the use of a constant pressure bomb, led to the discovery of an important kinetic relation connecting the rate of propagation of the zone of explosive reaction within the active gases, with the initial concentrations of those gases: s = K(sub 1)(A)(sup n1)(B)(sup n2)(C)(sup n3)------. By a method analogous to that followed in determining the effect of inert gases on the equilibrium constant K, the present paper records an attempt to determine their kinetic effect upon the expression given above.

Stevens, F W

1928-01-01

240

Process for treating gases in the ammonia synthesis. [separation and dehydration of gases leaving synthesis reactor  

Microsoft Academic Search

In the synthesis of ammonia, a process is disclosed for treating the gases flowing from the synthesis reactor wherein those gases flow through a film absorber countercurrent to a cooled aqueous film to extract ammonia which is withdrawn as a strong solution from the absorber and scrubbed gases are combined for recycle with a stream of fresh feed which is

Guadalupi

1977-01-01

241

Effects of traces of molecular gases (hydrogen, nitrogen) in glow discharges in noble gases  

NASA Astrophysics Data System (ADS)

The "Grimm" type of low pressure glow discharge source, introduced some forty years ago, has proved to be a versatile analytical source. A flat sample is used as the cathode and placed about 0.2mm away from the end of a hollow tubular anode leading to an obstructed discharge. When the source was first developed, it was used for the direct analysis of solid metallic samples by optical emission spectroscopy (OES), normally with argon as the plasma gas; it was soon found that, using suitable electrical parameters, the cathode material was sputtered uniformly from a circular crater of diameter equal to that of the tubular anode, so that the technique could be used for compositional depth profile analysis (CDPA). Over the years the capability and applications of the technique have steadily increased. The use of rf powered discharges now permits the analysis of non-conducting layers and samples; improved instrumental design now allows CDPA of ever thinner layers (e.g. resolution of layers 5 nm thick in multilayer stacks is possible). For the original bulk material application, pre-sputtering could be used to remove any surface contamination but for CDPA, analysis must start immediately the discharge is ignited, so that any surface contamination can introduce molecular gases into the plasma gas and have significant analytical consequences, especially for very thin layers; in addition, many types of samples now analysed contain molecular gases as components (either as occluded gas, or e.g. as a nitride or oxide), and this gas enters the discharge when the sample is sputtered. It is therefore important to investigate the effect of such foreign gases on the discharge, in particular on the spectral intensities and hence the analytical results. The presentation will concentrate mainly on the effect of hydrogen in argon discharges, in the concentration range 0-2 % v/v but other gas mixtures (e.g. Ar/N_2, Ne/H_2) will be considered for comparison. In general, the introduction of molecular gases can change the discharge impedance, alter the sputtering rate and crater profile and cause changes in the absolute and relative intensities of lines in both the atomic and ionic spectra of the sample element and the plasma gas. The authors wish to acknowledge financial support from EC funded Analytical Glow Discharge Research Training Network GLADNET, contract no. MRTN-CT-2006-035459. P. Smid thanks the Deutsche Forschungsgemeinschaft (Ref 436 TSE 17/7/06) for support while carrying out experiments at IFW Dresden.

Steers, E. B. M.; Smid, P.; Hoffmann, V.

2008-07-01

242

Prognostic Importance of Gleason 7 Disease Among Patients Treated With External Beam Radiation Therapy for Prostate Cancer: Results of a Detailed Biopsy Core Analysis  

SciTech Connect

Purpose: To analyze the effect of primary Gleason (pG) grade among a large cohort of Gleason 7 prostate cancer patients treated with external beam radiation therapy (EBRT). Methods and Materials: From May 1989 to January 2011, 1190 Gleason 7 patients with localized prostate cancer were treated with EBRT at a single institution. Of these patients, 613 had a Gleason 7 with a minimum of a sextant biopsy with nonfragmented cores and full biopsy core details available, including number of cores of cancer involved, percentage individual core involvement, location of disease, bilaterality, and presence of perineural invasion. Median follow-up was 6 years (range, 1-16 years). The prognostic implication for the following outcomes was analyzed: biochemical recurrence-free survival (bRFS), distant metastasis-free survival (DMFS), and prostate cancer-specific mortality (PCSM). Results: The 8-year bRFS rate for pG3 versus pG4 was 77.6% versus 61.3% (P<.0001), DMFS was 96.8% versus 84.3% (P<.0001), and PCSM was 3.7% versus 8.1% (P=.002). On multivariate analysis, pG4 predicted for significantly worse outcome in all parameters. Location of disease (apex, base, mid-gland), perineural involvement, maximum individual core involvement, and the number of Gleason 3+3, 3+4, or 4+3 cores did not predict for distant metastases. Conclusions: Primary Gleason grade 4 independently predicts for worse bRFS, DMFS, and PCSM among Gleason 7 patients. Using complete core information can allow clinicians to utilize pG grade as a prognostic factor, despite not having the full pathologic details from a prostatectomy specimen. Future staging and risk grouping should investigate the incorporation of primary Gleason grade when complete biopsy core information is used.

Spratt, Daniel E.; Zumsteg, Zach; Ghadjar, Pirus; Pangasa, Misha; Pei, Xin [Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, New York (United States)] [Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Fine, Samson W. [Department of Pathology, Memorial Sloan-Kettering Cancer Center, New York, New York (United States)] [Department of Pathology, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Yamada, Yoshiya; Kollmeier, Marisa [Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, New York (United States)] [Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Zelefsky, Michael J., E-mail: zelefskm@mskcc.org [Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, New York (United States)

2013-04-01

243

Toroidal cross capacitor for measuring the dielectric constant of gases  

Microsoft Academic Search

and it will be important whenever the dielectric constant of gases must be measured with the highest possible accuracy. Highly accurate measurements of the dielectric constant of helium were used to determine the thermodynamic tempera- ture in the range 4.2-27 K.6 We are planning even more accurate measurements of the dielectric constant of helium at 273.16 K for use as

Thomas J. Buckley

244

Low-mature gases and their resource potentiality  

Microsoft Academic Search

In the 80’s of last century, based on the advances in natural gas exploration practice, the concepts of bio-thermocatalytic\\u000a transitional-zone gas and early thermogenetic gas were proposed, and the lower limit R\\u000a o values for the formation and accumulation of thermogenetic natural gases of industrial importance have been extended to 0.3%–0.4%.\\u000a In accordance with the two-stage model established on the

Yongchang Xu; Xiaofeng Wang; Baoguang Shi

2009-01-01

245

Noble gases in the dynamic mantle  

Microsoft Academic Search

It is proposed that noble gases in the mantle reside mainly in a “hybrid pyroxenite” component that is formed as melt from old subducted oceanic crust reacts with surrounding refractory peridotite under mid-ocean ridges. The gases are presumed to have been acquired early in Earth history, and mixing under mid-ocean ridges of melts from pyroxenites and old crust would pass

Geoffrey F. Davies

2010-01-01

246

Facilitating Conceptual Change in Gases Concepts  

ERIC Educational Resources Information Center

The aim of this study is to investigate the effectiveness of conceptual change oriented instruction (CCOI) over traditionally designed chemistry instruction (TDCI) on overcoming 10th grade students' misconceptions on gases concepts. In addition, the effect of gender difference on students' understanding of gases concepts was investigated. The…

Cetin, Pinar Seda; Kaya, Ebru; Geban, Omer

2009-01-01

247

Reporting emissions of greenhouse gases in Canada  

Microsoft Academic Search

Non-carbon dioxide greenhouse gases are considered in “Canada's National Report on Climate Change: Actions to Meet Commitments Under the United Nations Framework Convention on Climate Change”. By including all major greenhouse gases and their anthropogenic sources and sinks using best available science, the Report provides a practical illustration of the “comprehensive approach” policy to implementing the Convention's requirements. In addition

Patrick Finlay; Robert Stobbs

1994-01-01

248

Primordial rare gases in unequilibrated ordinary chondrites.  

PubMed

The primordial gases of eight unequilibrated ordinary chondrites are strongly fractionated with respect to" cosmic" proportions. The absolute amounts are roughly proportional to the degree of disequilibration. Apparently, ordinary chondrites originally contained considerably larger amounts of primordial rare gases. PMID:17807955

Heymann, D; Mazor, E

1967-02-10

249

Removal of hydrogen sulfide from reducing gases  

Microsoft Academic Search

IGT's method of removing sulfur compounds from hot reducing fuel-gas streams requires no preliminary cooling and subsequent reheating of the gases. A melt of molten lead and a metal sulfide is contacted with the hot reducing gases to remove compounds such as hydrogen sulfide, carbonyl sulfide, and mercaptans. The lead and elemental sulfur are regenerated from the formed lead sulfide

Meissner

1976-01-01

250

Comparing Greenhouse Gases for Policy Purposes  

Microsoft Academic Search

In order to derive optimal policies for greenhouse gas emissions control, the discounted marginal damages of emissions from different gases must be compared. The greenhouse warming potential (GWP) index, which is most often used to compare greenhouse gases, is not based on such a damage comparison. This essay presents assumptions under which ratios of gas-specific discounted marginal damages reduce to

Richard Schmalensee

1993-01-01

251

BOOK REVIEW: Plasma Kinetics in Atmospheric Gases  

Microsoft Academic Search

The book Plasma Kinetics in Atmospheric Gases is a worthwhile contribution to the basic phenomena in nitrogen, oxygen and other atmospheric gases. It contains basic introductory chapters on relaxation in translational, rotational (short) and vibrational (extensive) distribution and on the physics of electron excitation and electron distribution functions. In the latter, electron beam excitation (i.e. high electron energies) are included.

M. Capitelli; C. M. Ferreira; B. F. Gordiets; A. I. Osipov

2001-01-01

252

Voluntary Reporting of Greenhouse Gases Archive  

EIA Publications

The Voluntary Reporting of Greenhouse Gases Program established a mechanism by which corporations, government agencies, individuals, voluntary organizations, etc., can report to the EIA, any actions taken that have or are expected to reduce/avoid emissions of greenhouse gases or sequester carbon.

Information Center

2011-02-01

253

The state of greenhouse gases in the atmosphere using global observations through 2010  

NASA Astrophysics Data System (ADS)

The Global Atmosphere Watch (GAW) Programme of the World Meteorological Organization (WMO) provides a framework for observing and assessing the state and development of environmental issues related to atmospheric composition, including greenhouse gases. It puts stringent requirements on the quality of the observations; these requirements are reviewed by the greenhouse gas science and measurement community at biennial WMO/IAEA Meetings on Carbon Dioxide, Other Greenhouse Gases, and Related Tracer Measurement Techniques. The 16th meeting was held in Wellington, New Zealand, on 25 - 28 October 2011 (http://www.niwa.co.nz/our-science/atmosphere/ggmt-2011). Surface observations are made at more than 100 stations worldwide for CO2 and CH4 and at a smaller number of stations for many other greenhouse gases. Results of the latest global analysis were published in the WMO/GAW Greenhouse Gas Bulletin in November 2011. It highlights the importance of N2O, the third most important long-lived greenhouse gas in the atmosphere. Globally averaged dry-air mole fractions of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) reached new highs in 2010, with CO2 at 389.0 ppm, CH4 at 1808 ppb and N2O at 323.2 ppb. These values are greater than those in pre-industrial times (before 1750) by 39%, 158% and 20%, respectively. An increase of the annual mean CO2 mole fraction from 2009 to 2010 amounted to 2.3 ppm, which is higher than the average growth rate for the 1990s (~ 1.5 ppm/yr) and the one for the past decade (~ 2.0 ppm/yr). The growth rate of CH4 decreased from ~ 13 ppb/yr during the early 1980s to near zero from 1999 to 2006. Since 2007, atmospheric CH4 has been increasing again. The 19 ppb rise from 2006 to 2009 was followed by a 5 ppb rise in 2010. The growth rate of N2O in 2010 was 0.8 ppb/yr which is comparable to the average over the last 10 years (0.75 ppb/yr). The NOAA Annual Greenhouse Gas Index (AGGI) shows that from 1990 to 2010, radiative forcing from nearly all long-lived greenhouse gases increased by 29% and reached 2.81W/m2, with CO2 accounting for nearly 80% of this increase. This radiative forcing corresponds to a CO2-eq mole fraction of 469.7 ppm, which falls in the middle of the IPCC AR4 category I scenario with CO2-eq in the range 445-490 ppm (corresponding to the projected global average temperature rise above pre-industrial level at equilibrium in the range of 2-2.4 degree C). The radiative forcing of N2O now exceeds that of CFC-12.

Tarasova, O. A.; Koide, H.; Dlugokencky, E.; Hall, B.; Montzka, S. A.; Krummel, P.; Brunke, E.; Scheel, H.-E.

2012-04-01

254

Hyperpolarized noble gases as contrast agents.  

PubMed

Hyperpolarized noble gases ((3)He and (129)Xe) can provide NMR signal enhancements of 10,000 to 100,000 times that of thermally polarized gases and have shown great potential for applications in lung magnetic resonance imaging (MRI) by greatly enhancing the sensitivity and contrast. These gases obtain a highly polarized state by employing a spin exchange optical pumping technique. In this chapter, the underlying physics of spin exchange optical pumping for production of hyperpolarized noble gases is explained and the basic components and procedures for building a polarizer are described. The storage and delivery strategies of hyperpolarized gases for in vivo imaging are discussed. Many of the problems that are likely to be encountered in practical experiments and the corresponding detailed approaches to overcome them are also discussed. PMID:21874479

Zhou, Xin

2011-01-01

255

Isotopic composition of gases from mud volcanoes  

SciTech Connect

A study has been made of the isotopic composition of the carbon in methane and carbon dioxide, as well as hydrogen in the methane, in the gases of mud volcanoes, for all main mud volcano areas in the USSR. The isotopic composition of carbon and hydrogen in methane shows that the gases resemble those of oil and gas deposits, while carbon dioxide of these volcanoes has a heavier isotopic composition with a greater presence of ''ultraheavy'' carbon dioxide. By the chemical and isotopic composition of gases, Azerbaidzhan and South Sakhalin types of mud volcano gases have been identified, as well as Bulganak subtypes and Akhtala and Kobystan varieties. Correlations are seen between the isotopic composition of gases and the geological build of mud volcano areas.

Valysaev, B.M.; Erokhin, V.E.; Grinchenko, Y.I.; Prokhorov, V.S.; Titkov, G.A.

1985-09-01

256

Importance timing  

NASA Astrophysics Data System (ADS)

Bayesian evidence Z = ? L(x)d?(x) is defined as likelihood L integrated over prior ?, and is often computed in that form -- with nested sampling as the preferred algorithm for passing from prior to posterior in large or complicated applications. However, a user may suspect that some locations x are more useful than others, and wish to guide the computation by using a suitable weight function w(x). In conventional importance sampling, such weights are incorporated by re-writing Z as ?(L/w)(wd?), using a weighted prior w? and correspondingly de-weighted likelihood L/w. Unfortunately, w cannot be updated during a run without altering the likelihood surfaces (which nested sampling requires to be fixed). Also, the normalization ? wd? must be known if the value of Z is to be retrieved. Importance timing removes those disadvantages by preserving the likelihood unchanged. Excess prior weight w is cancelled, not through L, but by adjusting the rate of the MCMC clock which defines termination of a trial exploration. This preserves the evidence value and enables the weights to be (slowly) learned as iterations proceed.

Skilling, John

2013-08-01

257

On the importance of searching for oscillations of the Jovian inner radiation belt with a quasi-period of 40 minutes  

NASA Astrophysics Data System (ADS)

Experiments aboard the Ulysses spacecraft discovered quasi-periodic bursts of relativistic electrons and of radio emissions with ~40-min period (QP-40) from the south polar direction of Jupiter in 1992 February. Such polar QP-40 burst activities were found to correlate well with arrivals of high-speed solar winds at Jupiter. We advance the physical scenario that the inner radiation belt (IRB) within a distance of ~2-3 RJ (where RJ is the radius of Jupiter), where relativistic electrons are known to be trapped using the diagnostics of synchrotron emissions, can execute global QP-40 magnetoinertial oscillations excited by arrivals of high-speed solar winds at the Jovian magnetosphere. Modulated by such QP-40 IRB oscillations, relativistic electrons trapped in the IRB may escape from the magnetic circumpolar regions during a certain phase of each 40-min period to form circumpolar QP-40 relativistic electron bursts. Highly beamed synchrotron emissions from such QP-40 burst electrons with small pitch angles relative to Jovian magnetic fields at ~30-40 RJ give rise to QP-40 radio bursts with typical frequencies <~0.2 MHz. We predict that the synchrotron brightness of the IRB should vary on QP-40 time-scales upon arrivals of high-speed solar winds with estimated magnitudes >~0.1 Jy, detectable by existing ground-based radio telescopes. The recent discovery of ~45-min pulsations of Jupiter's north polar X-ray hot spot by the High-Resolution Camera (HRC) of the Chandra spacecraft provides strong supporting circumstantial evidence that the IRB neighborhood did oscillate with QP-40 time-scales. Using the real-time solar wind data from the spacecraft Advanced Composition Explorer (ACE), we show here that such QP-40 pulsations of Jupiter's north polar X-ray hot spot did in fact coincide with the arrival of high-speed solar wind at Jupiter. We note also that properly sampled data of simultaneous far-ultraviolet images of auroral ovals obtained by the Hubble Space Telescope imaging spectrograph (HST-STIS) would have contained QP-40 oscillatory signatures. Based on our theoretical analysis, we offer several predictions that can be tested by further spacecraft and ground-based telescope observations.

Lou, Yu-Qing; Zheng, Chen

2003-09-01

258

Physics of intense, high energy radiation effects.  

SciTech Connect

This document summarizes the work done in our three-year LDRD project titled 'Physics of Intense, High Energy Radiation Effects.' This LDRD is focused on electrical effects of ionizing radiation at high dose-rates. One major thrust throughout the project has been the radiation-induced conductivity (RIC) produced by the ionizing radiation. Another important consideration has been the electrical effect of dose-enhanced radiation. This transient effect can produce an electromagnetic pulse (EMP). The unifying theme of the project has been the dielectric function. This quantity contains much of the physics covered in this project. For example, the work on transient electrical effects in radiation-induced conductivity (RIC) has been a key focus for the work on the EMP effects. This physics in contained in the dielectric function, which can also be expressed as a conductivity. The transient defects created during a radiation event are also contained, in principle. The energy loss lead the hot electrons and holes is given by the stopping power of ionizing radiation. This information is given by the inverse dielectric function. Finally, the short time atomistic phenomena caused by ionizing radiation can also be considered to be contained within the dielectric function. During the LDRD, meetings about the work were held every week. These discussions involved theorists, experimentalists and engineers. These discussions branched out into the work done in other projects. For example, the work on EMP effects had influence on another project focused on such phenomena in gases. Furthermore, the physics of radiation detectors and radiation dosimeters was often discussed, and these discussions had impact on related projects. Some LDRD-related documents are now stored on a sharepoint site (https://sharepoint.sandia.gov/sites/LDRD-REMS/default.aspx). In the remainder of this document the work is described in catergories but there is much overlap between the atomistic calculations, the continuum calculations and the experiments.

Hjalmarson, Harold Paul; Hartman, E. Frederick; Magyar, Rudolph J.; Crozier, Paul Stewart

2011-02-01

259

Use of reactive gases with broad-beam radio frequency ion sources for industrial applications  

NASA Astrophysics Data System (ADS)

Broad-beam ion sources are used for a number of important industrial etching and deposition applications, and the use of inductively coupled plasmas has greatly increased the feasibility of using beams of reactive gases, especially of chlorine and oxygen, but also of CO, CO2, CF4, CHF3, SF6, etc. In order to gain more understanding of the factors that affect the composition of beams of these gases, we have used a Hiden energy-dispersive quadrupole mass spectrometer to analyze the flux of ions and energetic particles produced by an Oxford Instruments 15 cm rf ion source. For all of the above gases, we have analyzed the effects of changing the operating conditions on the composition of the ion beam, and the fractional production of multiply charged ions; on the plasma potential (and the consequential divergence of the ion beam) and on the spread in energy of the ion beam. We discuss how these factors influence the correct use of the ion source in etching applications with these gases. It is important that the design of the ion source should be optimized for the process gases that are used. The source was originally optimized for use on argon. We discuss the effect of the design on the source's performance with the different gases, and we consider whether design changes would be appropriate for optimum performance on different gases. .

Schneider, St.; Jolly, T. W.; Kohlstedt, H.; Waser, R.

2004-07-01

260

Comparison of natural gases accumulated in Oligocene strata with hydrous pyrolysis gases from Menilite Shales of the Polish Outer Carpathians  

USGS Publications Warehouse

This study examined the molecular and isotopic compositions of gases generated from different kerogen types (i.e., Types I/II, II, IIS and III) in Menilite Shales by sequential hydrous pyrolysis experiments. The experiments were designed to simulate gas generation from source rocks at pre-oil-cracking thermal maturities. Initially, rock samples were heated in the presence of liquid water at 330 ??C for 72 h to simulate early gas generation dominated by the overall reaction of kerogen decomposition to bitumen. Generated gas and oil were quantitatively collected at the completion of the experiments and the reactor with its rock and water was resealed and heated at 355 ??C for 72 h. This condition simulates late petroleum generation in which the dominant overall reaction is bitumen decomposition to oil. This final heating equates to a cumulative thermal maturity of 1.6% Rr, which represents pre-oil-cracking conditions. In addition to the generated gases from these two experiments being characterized individually, they are also summed to characterize a cumulative gas product. These results are compared with natural gases produced from sandstone reservoirs within or directly overlying the Menilite Shales. The experimentally generated gases show no molecular compositions that are distinct for the different kerogen types, but on a total organic carbon (TOC) basis, oil prone kerogens (i.e., Types I/II, II and IIS) generate more hydrocarbon gas than gas prone Type III kerogen. Although the proportionality of methane to ethane in the experimental gases is lower than that observed in the natural gases, the proportionality of ethane to propane and i-butane to n-butane are similar to those observed for the natural gases. ??13C values of the experimentally generated methane, ethane and propane show distinctions among the kerogen types. This distinction is related to the ??13C of the original kerogen, with 13C enriched kerogen generating more 13C enriched hydrocarbon gases than kerogen less enriched in 13C. The typically assumed linear trend for ??13C of methane, ethane and propane versus their reciprocal carbon number for a single sourced natural gas is not observed in the experimental gases. Instead, the so-called "dogleg" trend, exemplified by relatively 13C depleted methane and enriched propane as compared to ethane, is observed for all the kerogen types and at both experimental conditions. Three of the natural gases from the same thrust unit had similar "dogleg" trends indicative of Menilite source rocks with Type III kerogen. These natural gases also contained varying amounts of a microbial gas component that was approximated using the ????13C for methane and propane determined from the experiments. These approximations gave microbial methane components that ranged from 13-84%. The high input of microbial gas was reflected in the higher gas:oil ratios for Outer Carpathian production (115-1568 Nm3/t) compared with those determined from the experiments (65-302 Nm3/t). Two natural gas samples in the far western part of the study area had more linear trends that suggest a different organic facies of the Menilite Shales or a completely different source. This situation emphasizes the importance of conducting hydrous pyrolysis on samples representing the complete stratigraphic and lateral extent of potential source rocks in determining specific genetic gas correlations. ?? 2009 Elsevier Ltd.

Kotarba, M. J.; Curtis, J. B.; Lewan, M. D.

2009-01-01

261

Impact degassing of water and noble gases from silicates  

NASA Technical Reports Server (NTRS)

Previous shock experiments by Ahrens and his colleagues show that degassing of H2O and CO2 occurs at 8-65GPa from hydrous minerals such as serpentine. In early solar system, the impact degassing would have played an important part in the formation of primary-atmospheres of the terrestrial planets. However, degassing conditions of noble gases are not well-known because there are few experiments for them. We conducted some shock recovery experiments to investigate the degassing condition and to understand the degassing mechanisms of water and noble gases. We used natural richterites (Ri), amphibolites (Am), serpentines (Sep) and orthoclases (or) as target samples. These, except Sep, contain radiogenic noble gases such as (40)Ar. The samples were put in stainless steel containers, and were show by a rail gun at ISAS or single-stage powder guns at Nagoya or Tohoku University, Japan. We used two kinds of containers: 'open' type containers having a ventilating path for released volatiles for most of samples and 'closed' type ones for some samples for comparison. On Ri and Sep, we made shock experiments for pre-heated (at 400-500 C) and unheated targets, and for powdered and uncrushed samples. Water and noble gases were analyzed both for the recovered shocked samples and the unshocked original samples, and the fractions of the degassed volatiles were calculated by comparing them. Water content in the sample was analyzed by thermo-gravimetry. Noble gases were extracted by heating the samples under high vacuum and analyzed with a sector-type mass spectrometer.

Azuma, S.; Hiyagon, H.; Iijima, Y.; Syono, Y.

1994-01-01

262

Impact degassing of water and noble gases from silicates  

NASA Astrophysics Data System (ADS)

Previous shock experiments by Ahrens and his colleagues show that degassing of H2O and CO2 occurs at 8-65GPa from hydrous minerals such as serpentine. In early solar system, the impact degassing would have played an important part in the formation of primary-atmospheres of the terrestrial planets. However, degassing conditions of noble gases are not well-known because there are few experiments for them. We conducted some shock recovery experiments to investigate the degassing condition and to understand the degassing mechanisms of water and noble gases. We used natural richterites (Ri), amphibolites (Am), serpentines (Sep) and orthoclases (or) as target samples. These, except Sep, contain radiogenic noble gases such as (40)Ar. The samples were put in stainless steel containers, and were show by a rail gun at ISAS or single-stage powder guns at Nagoya or Tohoku University, Japan. We used two kinds of containers: 'open' type containers having a ventilating path for released volatiles for most of samples and 'closed' type ones for some samples for comparison. On Ri and Sep, we made shock experiments for pre-heated (at 400-500 C) and unheated targets, and for powdered and uncrushed samples. Water and noble gases were analyzed both for the recovered shocked samples and the unshocked original samples, and the fractions of the degassed volatiles were calculated by comparing them. Water content in the sample was analyzed by thermo-gravimetry. Noble gases were extracted by heating the samples under high vacuum and analyzed with a sector-type mass spectrometer.

Azuma, S.; Hiyagon, H.; Iijima, Y.; Syono, Y.

263

BRIEF COMMUNICATIONS: Enhancement of the breakdown threshold at the surface of a target in a mixture of gases  

Microsoft Academic Search

Enhancement of the breakdown threshold of mixed atomic and molecular gases subjected to laser radiation was predicted and investigated experimentally. The breakdown threshold depended nonmonotonically on the concentration of nitrogen in a mixture of Ar and N2. The threshold values of the laser radiation intensity for a mixture could be 1.5-2 times greater than the thresholds of each of the

E. V. Dan'shchikov; V. A. Dymshakov; F. V. Lebedev; A. V. Ryazanov

1982-01-01

264

Driven fragmentation of granular gases.  

PubMed

The dynamics of homogeneously heated granular gases which fragment due to particle collisions is analyzed. We introduce a kinetic model which accounts for correlations induced at the grain collisions and analyze both the kinetics and relevant distribution functions these systems develop. The work combines analytical and numerical studies based on direct simulation Monte Carlo calculations. A broad family of fragmentation probabilities is considered, and its implications for the system kinetics are discussed. We show that generically these driven materials evolve asymptotically into a dynamical scaling regime. If the fragmentation probability tends to a constant, the grain number diverges at a finite time, leading to a shattering singularity. If the fragmentation probability vanishes, then the number of grains grows monotonously as a power law. We consider different homogeneous thermostats and show that the kinetics of these systems depends weakly on both the grain inelasticity and driving. We observe that fragmentation plays a relevant role in the shape of the velocity distribution of the particles. When the fragmentation is driven by local stochastic events, the long velocity tail is essentially exponential independently of the heating frequency and the breaking rule. However, for a Lowe-Andersen thermostat, numerical evidence strongly supports the conjecture that the scaled velocity distribution follows a generalized exponential behavior f(c) approximately exp(-cn) , with n approximately 1.2 , regarding less the fragmentation mechanisms. PMID:18643255

Cruz Hidalgo, Raúl; Pagonabarraga, Ignacio

2008-06-01

265

Study of transient jet gases  

NASA Astrophysics Data System (ADS)

This work involves the use of flash lamp schlieren and the development of flash lamp light slicing (planar imaging) and their employment in visualization of transient gas jets discharging into the atmosphere and the mixing that ensues. Details of the flash lamp light slicing system design are provided. Visualization of flows from a pulsed valve discharge system and a shock tube open at the downstream end of the driven section are used to simulate real discharges. Gas flow Mach numbers for discharges of air into the atmosphere range to about 0.4. Axial light slicing images show development of the starting jets, including the formation of the starting vortex and coherent structures that form along the jet shaft. Transverse light slicing images reveal the development of scallops and cusps inside the head of the jet. Voids in the jet were observed at about 4 to 6 diameters from the exit plane. This may imply that ambient and jet gases differentiate at some points downstream. These features suggest cyclic development of jet features. The results can also be used to validate and calibrate computational fluid dynamic (CFD) computer codes used to predict the behavior of fluids under varying initial and boundary conditions.

Saber, Aaron Jaan

1988-03-01

266

Driven fragmentation of granular gases  

NASA Astrophysics Data System (ADS)

The dynamics of homogeneously heated granular gases which fragment due to particle collisions is analyzed. We introduce a kinetic model which accounts for correlations induced at the grain collisions and analyze both the kinetics and relevant distribution functions these systems develop. The work combines analytical and numerical studies based on direct simulation Monte Carlo calculations. A broad family of fragmentation probabilities is considered, and its implications for the system kinetics are discussed. We show that generically these driven materials evolve asymptotically into a dynamical scaling regime. If the fragmentation probability tends to a constant, the grain number diverges at a finite time, leading to a shattering singularity. If the fragmentation probability vanishes, then the number of grains grows monotonously as a power law. We consider different homogeneous thermostats and show that the kinetics of these systems depends weakly on both the grain inelasticity and driving. We observe that fragmentation plays a relevant role in the shape of the velocity distribution of the particles. When the fragmentation is driven by local stochastic events, the long velocity tail is essentially exponential independently of the heating frequency and the breaking rule. However, for a Lowe-Andersen thermostat, numerical evidence strongly supports the conjecture that the scaled velocity distribution follows a generalized exponential behavior f(c)˜exp(-cn) , with n?1.2 , regarding less the fragmentation mechanisms.

Cruz Hidalgo, Raúl; Pagonabarraga, Ignacio

2008-06-01

267

Sun and dust versus greenhouse gases: an assessment of their relative roles in global climate change  

NASA Astrophysics Data System (ADS)

Many mechanisms, including variations in solar radiation and atmospheric aerosol concentrations, compete with anthropogenic greenhouse gases as causes of global climate change. Comparisons of available data show that solar variability will not counteract greenhouse warming and that future observations will need to be made to quantify the role of tropospheric aerosols, for example.

Hansen, James E.; Lacis, Andrew A.

1990-08-01

268

Theory of two-atom coherence in gases. II. Continuous-wave spectra  

Microsoft Academic Search

General expressions are derived for the spectral line shapes of resonance absorption and scattering of coherent radiation in collision-broadened gases, taking into account effects of coherent excitation of two or more atoms (or molecules), as steady-state solutions of a hierarchy of master equations described in a previous publication (paper I). Coupling between the coherent motions of the atoms, provided by

Abraham Ben-Reuven

1980-01-01

269

Trace Gases and Aerosol in the Boundary Layer of the Northern Asia: TROICA Experiments  

Microsoft Academic Search

The TROICA experiment (Transcontinental Observations Into the Chemistry of the Atmosphere) started in 1995. A mobile railroad laboratory is being used for measurements of atmospheric gases, aerosol, solar radiation and meteorological parameters. The laboratory wagon is directly coupled to the locomotive of a passenger train traveling along electrified railroads of Russia. Eleven expeditions have been conducted to the moment of

N. F. Elanksy; A. E. Aloyan; E. V. Berezina; A. S. Elokhov; C. A. Brenninkmeijer; V. M. Kopeikin; K. B. Moeseenko; O. V. Lavrova; N. V. Pankratova; A. N. Safronov; R. A. Shumsky; A. I. Skorokhod; O. A. Tarasova; A. V. Vivchar; A. M. Grisenko

2007-01-01

270

Sun and dust versus greenhouse gases: an assessment of their relative roles in global climate change  

Microsoft Academic Search

Many mechanisms, including variations in solar radiation and atmospheric aerosol concentrations, compete with anthropogenic greenhouse gases as causes of global climate change. Comparisons of available data show that solar variability will not counteract greenhouse warming and that future observations will need to be made to quantify the role of tropospheric aerosols, for example.

James E. Hansen; Andrew A. Lacis

1990-01-01

271

Sun and dust versus greenhouse gases - An assessment of their relative roles in global climate change  

NASA Technical Reports Server (NTRS)

Many mechanisms, including variations in solar radiation and atmospheric aerosol concentrations, compete with anthropogenic greenhouse gases as causes of global climate change. Comparisons of available data show that solar variability will not counteract greenhouse warming and that future observations will need to be made to quantify the role of tropospheric aerosols, for example.

Hansen, James E.; Lacis, Andrew A.

1990-01-01

272

The effect of volcanic gases on quantitative temperature measurements using the FLIR thermal camera  

NASA Astrophysics Data System (ADS)

Ground-based thermal imagery is being increasingly used as a tool for volcano surveillance, however, the radiative transfer effect of volcanic gases and aerosols has been largely overlooked. This is potentially very important, as the concentrations of volcanic gas present in, for example, the summit crater of Stromboli may be very high. Here, we calculate the magnitude of the effect of volcanic and atmospheric gas absorptions on radiometric measurements collected with a FLIR thermaCAM PM695 during mild explosive events on Stromboli volcano, Italy. We use measurements of gas path amounts collected by Fourier transform infrared spectrometry to constrain a radiative transfer model and demonstrate that if the effect of absorptions by water vapour and sulphur dioxide is not accounted for then large systematic errors will be introduced in observed temperatures. We also examine the effect of a volcanic plume on the high resolution spectrum in the wavelength range of interest for the FLIR, and determine that aerosols and SiF4 may well be ulterior sources of discrepancy between observed and actual temperatures.

Sawyer, G.; Burton, M. R.; Oppenheimer, C.

2005-12-01

273

Climate-chemical interactions and effects of changing atmospheric trace gases  

Microsoft Academic Search

The paper considers trace gas-climate effects including the greenhouse effect of polyatomic trace gases, the nature of the radiative-chemical interactions, and radiative-dynamical interactions in the stratosphere, and the role of these effects in governing stratospheric climate change. Special consideration is given to recent developments in the investigations of the role of oceans in governing the transient climate responses, and a

V. Ramanathan; L. Callis; R. Cess; J. Hansen; I. Isaksen; W. Kuhn; A. Lacis; F. Luther; J. Mahlman; R. Reck

1987-01-01

274

Solar radiation resource assessment  

SciTech Connect

The bulletin discusses the following: introduction; Why is solar radiation resource assessment important Understanding the basics; the solar radiation resource assessment project; and future activities.

Not Available

1990-11-01

275

46 CFR 194.20-17 - Compressed gases.  

Code of Federal Regulations, 2010 CFR

...Storerooms § 194.20-17 Compressed gases. (a) Nonflammable compressed gases (excluding oxygen) may be securely stowed in the storeroom...storeroom. (b) Flammable compressed gases and oxygen shall be stowed in accordance with...

2010-10-01

276

The In-Vitro Transport of (238)PLUTONIUM Oxide and (239)PLUTONIUM Oxide Through a Membrane Filter and its Importance for Internal Radiation Dosimetry.  

NASA Astrophysics Data System (ADS)

These experiments were designed to determine if ('238)PuO(,2), due to its higher specific activity and attendant aggregate recoil, undergoes higher transfer through a membrane filter into an interstitial human alveolar lung fluid simulant than ('239)PuO(,2). The rate at which such transfer occurs was determined in an in-vitro chamber designed to simulate residence characteristics of particles of insoluble plutonium oxides in human alveolar interstitium. The ratio of the rate of ('238)Pu/('239)Pu transfer was 138 (+OR -) 76%. Calculations were performed to assess the importance of this finding in terms of the internal dosimetry of insoluble ('238)Pu using methods and models recommended by the International Commission on Radiological Protection. Three cases were evaluated, namely integral 50-year dose commitment, urinary excretion after single acute intake and urinary excretion rate during chronic constant intake. It was found that integral 50-year dose commitments were not influenced by the rate of plutonium transfer from the pulmonary compartment to blood. The evaluation of calculated urinary excretion data after a single acute inhalation intake showed that in the early period, up to about 30 days post exposure, urinary excretion of ('238)PuO(,2) may be 2 to 10 times higher than the urinary excretion rate for ('238)PuO(,2) predicted by the ICRP reference model. From about 50 days to approximately 1000 days the calculated urinary excretion rate for ('238)PuO(,2) may be lower than that predicted by the reference model by a factor of 2 to 10. In the case of chronic constant intake the calculated urinary excretion rate for ('238)PuO(,2) may be up to a factor of 2 higher than that predicted by the reference ICRP Model.

Ryan, Michael Terrance

277

Noble gases in a new meteorite, the Omolon pallasite  

NASA Astrophysics Data System (ADS)

The Omolon meteorite was observed to reach the earth's surface in May 1981 over a large area of the Magadan region, USSR; samples of the pallasite were collected in 1982 near the Omolon river, 64 deg 01 min N, 161 deg 48 min E. The objective of the study was to investigate the isotope composition and noble gas concentration of olivine from the Omolon pallasite in order to identify various genetic components of the gases, estimate the radiation age of the meteorite, and determine the time of olivine crystallization. Data on the isotope composition and contents of He, Ne, Ar, Kr, and Xe are presented, and some characteristic features of the isotope composition are discussed. The radiation age of the pallasite is estimated at 94 +/- 18 million years.

Shukoliukov, Iu. A.; Klimenko, Iu. V.; Koliasnikov, Iu. A.; Petaev, M. I.

278

Foundations of radiation hydrodynamics  

Microsoft Academic Search

This book is the result of an attempt, over the past few years, to gather the basic tools required to do research on radiating flows in astrophysics. The microphysics of gases is discussed, taking into account the equation of state of a perfect gas, the first and second law of thermodynamics, the thermal properties of a perfect gas, the distribution

D. Mihalas; B. W. Mihalas

1984-01-01

279

Light Collection in Liquid Noble Gases  

ScienceCinema

Liquid noble gases are increasingly used as active detector materials in particle and nuclear physics. Applications include calorimeters and neutrino oscillation experiments as well as searches for neutrinoless double beta decay, direct dark matter, muon electron conversion, and the neutron electric dipole moment. One of the great advantages of liquid noble gases is their copious production of ultraviolet scintillation light, which contains information about event energy and particle type. I will review the scintillation properties of the various liquid noble gases and the means used to collect their scintillation light, including recent advances in photomultiplier technology and wavelength shifters.

280

The Biological and Toxicological Activity of Gases and Vapors  

PubMed Central

A large amount of data on the biological and toxicological activity of gases and vapors has been collected from the literature. Processes include sensory irritation thresholds, the Alarie mouse test, inhalation anesthesia, etc. It is shown that a single equation using only five descriptors (properties of the gases and vapors) plus a set of indicator variables for the given processes can correlate 643 biological and non-lethal toxicological activities of ‘non-reactive’ compounds with a standard deviation of 0.36 log unit. The equation is scaled to sensory irritation thresholds obtained by the procedure of Cometto-Muñiz, and Cain, and provides a general equation for the prediction of sensory irritation thresholds in man. It is suggested that differences in biological/toxicological activity arise primarily from transport from the gas phase to a receptor phase or area, except for odor detection thresholds where interaction with a receptor(s) is important.

Sanchez-Moreno, Ricardo; Gil-Lostes, Javier; Acree, William E.; Cometto-Muniz, J. Enrique; Cain, William S.

2010-01-01

281

Natural and anthropogenic trace gases in the southern hemisphere  

NASA Technical Reports Server (NTRS)

The complexity of the global environment makes it necessary that many important trace gases in the earth's atmosphere be measured on a global scale before predictions can be made regarding the effects of human activities on the environment. A description is presented of measurements of 14 atmospheric trace gases in the lower atmosphere (0-4 km) of the southern hemisphere. Concentrations are considered of CCl3F, CCl2F2, CHClF2, C2.Cl3.F3, CH3CCl3, CCl4, C2.Cl4, CH3I, CHCl3, CO, CH3Cl, CH4, N2O, and OCS. The obtained data are analyzed and interpreted to statistically quantify the possible differences of concentrations in and above the boundary layer, to model the vertical profile of CH3I, and to use the data in support of previous findings that CH4 is increasing in the atmosphere.

Rasmussen, R. A.; Khalil, M. A. K.; Crawford, A. J.; Fraser, P. J.

1982-01-01

282

Spectroscopy and Photoreactivity of Atmospheric Trace Gases.  

NASA Astrophysics Data System (ADS)

This thesis explores in detail some aspects of light absorption and light initiated chemical reactions in the atmosphere. The specific themes involved in this work include: laboratory spectroscopic measurements of atmospheric trace gases; fundamental studies of chemical reaction dynamics and the influence of weakly-bound complexes on reactivity; and the atmospheric relevance of the photoreactions of complexes. Laboratory studies of ultraviolet-visible (UV -VIS) absorption cross sections are necessary for the interpretation of measurements made in the field. The development and application of a new methodology for measuring high resolution UV-VIS absorption cross sections of molecules and radicals at atmospheric conditions are described. The instrument is based on a commercial Fourier transform spectrometer used in conjunction with a supersonic jet expansion for sample preparation. Infrared spectra are used to characterize sample conditions such as the temperature and the abundance of interferences. High resolution UV-VIS cross sections of two important atmospheric trace gases, nitrogen dioxide and chlorine dioxide, were measured at 200 +/- 20 K, which is characteristic of temperatures in the lower stratosphere. The second part of the thesis focuses on light initiated reactions of molecular complexes. Calculations of the atmospheric rate of photolysis of the ozone-water complex, O_3cdotH _2O, and its potential role as a source of OH in the troposphere are discussed. This work represents a new perspective on the role of weakly bound complexes in the atmosphere, because it proposes direct atmospheric photodissociation of such species. The calculations show that O_3cdotH_2 O photolysis is a potentially significant tropospheric OH source. Studies of the reactions of O(^1 D) with methane and propane monomers and clusters are also presented. Crossed molecular beams were used to prepare the reactants, and laser induced fluorescence was applied to the detection of the OH product. Energy distributions in different OH product degrees of freedom, including translation, vibration, and rotation, are reported. From this data, the mechanisms for the reactions of O( ^1D) with methane, propane and their clusters are established.

Frost, Gregory John

1995-01-01

283

Remote monitoring of volcanic gases using passive Fourier transform spectroscopy  

SciTech Connect

Volcanic gases provide important insights on the internal workings of volcanoes and changes in their composition and total flux can warn of impending changes in a volcano`s eruptive state. In addition, volcanoes are important contributors to the earth`s atmosphere, and understanding this volcanic contribution is crucial for unraveling the effect of anthropogenic gases on the global climate. Studies of volcanic gases have long relied upon direct in situ sampling, which requires volcanologists to work on-site within a volcanic crater. In recent years, spectroscopic techniques have increasingly been employed to obtain information on volcanic gases from greater distances and thus at reduced risk. These techniques have included UV correlation spectroscopy (Cospec) for SO{sub 2} monitoring, the most widely-used technique, and infrared spectroscopy in a variety of configurations, both open- and closed-path. Francis et al. have demonstrated good results using the sun as the IR source. This solar occultation technique is quite useful, but puts rather strong restrictions on the location of instrument and is thus best suited to more accessible volcanoes. In order to maximize the flexibility and range of FTIR measurements at volcanoes, work over the last few years has emphasized techniques which utilize the strong radiance contrast between the volcanic gas plume and the sky. The authors have successfully employed these techniques at several volcanoes, including the White Island and Ruapehu volcanoes in New Zealand, the Kilauea volcano on Hawaii, and Mt. Etna in Italy. But Popocatepetl (5452 m), the recently re-awakened volcano 70 km southeast of downtown Mexico City, has provided perhaps the best examples to date of the usefulness of these techniques.

Love, S.P.; Goff, F.; Counce, D.; Schmidt, S.C. [Los Alamos National Lab., NM (United States); Siebe, C.; Delgado, H. [Univ. Nactional Autonoma de Mexico, Coyoacan (Mexico)

1999-06-01

284

Toxicity of Pyrolysis Gases from Elastomers.  

National Technical Information Service (NTIS)

The toxicity of the pyrolysis gases from six elastomers was investigated. The elastomers were polyisoprene (natural rubber), styrene-butadiene rubber (SBR), ethylene propylene diene terpolymer (EPDM), acrylonitrile rubber, chlorosulfonated polyethylene ru...

A. N. Solis C. J. Hilado D. A. Kourtides J. A. Parker K. L. Kosola

1977-01-01

285

Electron Capture and Drift in Polyatomic Gases.  

National Technical Information Service (NTIS)

Electron drift velocities and lateral diffusion coefficients for a number of polyatomic gases were employed to determine mobilities, mean fractional energy losses per collision, stopping rates, derivatives of stopping rates with respect to the mean electr...

K. S. Gant

1976-01-01

286

Voluntary reporting of greenhouse gases, 1995  

SciTech Connect

The Voluntary Reporting Program for greenhouse gases is part of an attempt by the U.S. Government to develop innovative, low-cost, and nonregulatory approaches to limit emissions of greenhouse gases. It is one element in an array of such programs introduced in recent years as part of the effort being made by the United States to comply with its national commitment to stabilize emissions of greenhouse gases under the Framework Convention on Climate Change. The Voluntary Reporting Program, developed pursuant to Section 1605(b) of the Energy Policy Act of 1992, permits corporations, government agencies, households, and voluntary organizations to report to the Energy Information Administration (EIA) on actions taken that have reduced or avoided emissions of greenhouse gases.

NONE

1996-07-01

287

Absorption of Submillimeter Radiation by Battlefield Gases. Part II.  

National Technical Information Service (NTIS)

The purpose of this report is to investigate properties of the atmosphere likely present in a land battlefield encounter, and to point out the impact of these properties which might affect the use of submillimeter wavelength electro-optic devices. The mea...

D. H. Leslie J. L. Manning

1980-01-01

288

Noble gases in the dynamic mantle  

NASA Astrophysics Data System (ADS)

It is proposed that noble gases in the mantle reside mainly in a "hybrid pyroxenite" component that is formed as melt from old subducted oceanic crust reacts with surrounding refractory peridotite under mid-ocean ridges. The gases are presumed to have been acquired early in Earth history, and mixing under mid-ocean ridges of melts from pyroxenites and old crust would pass the noble gases to successive generations of pyroxenites. Much of the complement of noble gases would not be erupted at mid-ocean ridges and would recirculate in the mantle, so the hybrid pyroxenite would degas rather slowly over Earth history. The hybrid pyroxenite would also be denser than average mantle and would tend to settle into the D? zone at the base of the mantle, in the same way as subducted oceanic crust. Because residence times in D? are longer than in the rest of the mantle, the D? pyroxenite would be less degassed and its noble gases would be less radiogenic than that in the mid-ocean ridge basalt (MORB) source. Plumes could therefore tap a mixture of old, degassed oceanic crust and less degassed hybrid pyroxenite. This could resolve the long-standing question of the source of unradiogenic helium in many ocean island basalts (OIBs). Abundances of noble gases are not very well constrained and are plausibly larger than conventional estimates, which would remove the need for a large, deep, "undegassed" reservoir. The 40Ar mass balance may be satisfied if account is taken of uncertainties in the potassium content of the continental crust and the bulk silicate Earth and in the Earth's total budget of 40Ar. A relatively simple quantitative theory for the evolution of the noble gases is presented that accounts for the present concentrations and isotopic compositions of helium, neon, and argon in the MORB and OIB source regions. In particular, it confirms that longer residence times in D? can account for the less radiogenic noble gases in OIBs.

Davies, Geoffrey F.

2010-03-01

289

Quantum Polarization Spectroscopy of Ultracold Spinor Gases  

NASA Astrophysics Data System (ADS)

We propose a method for the detection of ground state quantum phases of spinor gases through a series of two quantum nondemolition measurements performed by sending off-resonant, polarized light pulses through the gas. Signatures of various mean-field as well as strongly correlated phases of F=1 and F=2 spinor gases obtained by detecting quantum fluctuations and mean values of polarization of transmitted light are identified.

Eckert, K.; Zawitkowski, ?.; Sanpera, A.; Lewenstein, M.; Polzik, E. S.

2007-03-01

290

Rheology of molten polystyrene with dissolved gases  

Microsoft Academic Search

Dissolved gases in polymers behave as excellent plasticizers, reducing viscosity significantly through the chain dilution effect and the addition of free volume. Rheological measurements and theoretical modeling are presented for molten polystyrene with dissolved gases, including carbon dioxide, 1,1-difluoroethane (R152a), and 1,1,1,2-tetrafluoroethane (R134a), which are considered to be environmentally acceptable for replacing previous ozone-depleting hydrochlorocarbon (HFC) refrigerants.^ A modified pressurized

Choongyong Kwag

1998-01-01

291

Quantum Polarization Spectroscopy of Ultracold Spinor Gases  

SciTech Connect

We propose a method for the detection of ground state quantum phases of spinor gases through a series of two quantum nondemolition measurements performed by sending off-resonant, polarized light pulses through the gas. Signatures of various mean-field as well as strongly correlated phases of F=1 and F=2 spinor gases obtained by detecting quantum fluctuations and mean values of polarization of transmitted light are identified.

Eckert, K. [Grup de Fisica Teorica, Universitat Autonoma de Barcelona, E-08193 Bellaterra (Spain); Zawitkowski, L. [Centrum Fizyki Teoretycznej, Polska Akademia Nauk, Warsaw 02668 (Poland); Sanpera, A. [ICREA and Grup de Fisica Teorica, Universitat Autonoma de Barcelona, E-08193 Bellaterra (Spain); Lewenstein, M. [ICREA and ICFO-Institut de Ciencies Fotoniques, E-08860 Castelldefels, Barcelona (Spain); Polzik, E. S. [ICFO-Institut de Ciencies Fotoniques, E-08860 Castelldefels, Barcelona (Spain); Niels Bohr Institute, Danish Quantum Optics Center-QUANTOP, Copenhagen University, Blegdamsvej 17, Copenhagen 2100 (Denmark)

2007-03-09

292

Greenhouse gases from animal husbandry: mitigation options  

Microsoft Academic Search

Abatement strategies for direct emissions of greenhouse gases from animal husbandry are discussed. The reduction options are\\u000a divided into preventive and `end of pipe' options. Preventive measures reduce either the carbon and nitrogen input into the\\u000a system of animal husbandry or their output from the system, respectively. `End of pipe' measures reduce the formation of greenhouse\\u000a gases from carbon and

Joachim Clemens; Heinz-Jürgen Ahlgrimm

2001-01-01

293

Abatement of Greenhouse Gases: Does Location Matter?  

Microsoft Academic Search

Today's climate policy is based on the assumption that the location of emissions reductions has no impact on the overall climate\\u000a effect. However, this may not be the case since reductions of greenhouse gases generally will lead to changes in emissions\\u000a of short-lived gases and aerosols. Abatement measures may be primarily targeted at reducing CO2, but may also simultaneously reduce

Terje Berntsen; Jan Fuglestvedt; Gunnar Myhre; Frode Stordal; Tore F. Berglen

2006-01-01

294

Ultra Secure High Reliability Wireless Radiation Monitor.  

National Technical Information Service (NTIS)

Radiation monitoring in nuclear facilities is essential to safe operation of the equipment as well as protecting personnel. In specific, typical air monitoring of radioactive gases or particulate involves complex systems of valves, pumps, piping and elect...

D. Shull G. Reeves J. Cordaro M. Farrar

2011-01-01

295

Radiation Studies of Metal-Oxygen Mixtures.  

National Technical Information Service (NTIS)

Many problems involving the prediction of radiance from heated gases or plasmas containing metals and their oxides are limited in the reliability of their solution because relevant spectroscopic properties of the radiating species are not known. Despite s...

M. G. Dunn W. H. Wurster C. E. Treanor

1975-01-01

296

Classification and generation of terrestrial rare gases  

NASA Technical Reports Server (NTRS)

A Kr-84/Xe-130 versus Ne-20/Ar-36 diagram is a very useful format with which to study the elemental ratios of rare gases from terrestrial materials. It can separate not only the three types of rare gases which Ozima and Alexander (1976) classified but also the 'planetary' type rare gases from the other three types of rare gases. When all the available terrestrial rare gas data are plotted in a Kr-84/Xe-130 versus Ne-20/Ar-36 diagram, several observations can be made. First, most of the analyses of rare gases from shales yield Kr-84/Xe-130 ratios between the 'planetary' and atmospheric values. If, however, the atmosphere's high Kr-84/Xe-130 ratio was produced by the selective adsorption of xenon onto shales from an initially 'planetary' atmosphere, as is widely accepted, then the Kr-84/Xe-130 ratio in shales should be even lower than the 'planetary' value. Second, the rare gas pattern in the quenched rims of submarine basalts may be explained as fractionated samples of the rare gases in sea water.

Saito, K.

1978-01-01

297

Source gases: Concentrations, emissions, and trends  

NASA Technical Reports Server (NTRS)

Source gases are defined as those gases that influence levels of stratospheric ozone (O3) by transporting species containing halogen, hydrogen, and nitrogen to the stratosphere. Examples are the CFC's, methane (CH4), and nitrous oxide (N2O). Other source gases that also come under consideration in an atmospheric O3 context are those that are involved in the O3 or hydroxyl (OH) radical chemistry of the troposphere. Examples are CH4, carbon monoxide (CO), and nonmethane hydrocarbons (NMHC's). Most of the source gases, along with carbon dioxide (CO2) and water vapor (H2O), are climatically significant and thus affect stratospheric O3 levels by their influence on stratospheric temperatures. Carbonyl sulphide (COS) could affect stratospheric O3 through maintenance of the stratospheric sulphate aerosol layer, which may be involved in heterogeneous chlorine-catalyzed O3 destruction. The previous reviews of trends and emissions of source gases, either from the context of their influence on atmospheric O3 or global climate change, are updated. The current global abundances and concentration trends of the trace gases are given in tabular format.

Fraser, Paul J.; Harriss, Robert; Penkett, Stuart A.; Makide, Yoshihiro; Sanhueza, Eugenio; Alyea, Fred N.; Rowland, F. Sherwood; Blake, Don; Sasaki, Toru; Cunnold, Derek M.

1991-01-01

298

Correlation of heat transfer for the zero pressure gradient hypersonic laminar boundary layer for several gases  

NASA Technical Reports Server (NTRS)

A theoretical study of heat transfer for zero pressure gradient hypersonic laminar boundary layers for various gases with particular application to the flows produced in an expansion tube facility was conducted. A correlation based on results obtained from solutions to the governing equations for five gases was formulated. Particular attention was directed toward the laminar boundary layer shock tube splitter plates in carbon dioxide flows generated by high speed shock waves. Computer analysis of the splitter plate boundary layer flow provided information that is useful in interpreting experimental data obtained in shock tube gas radiation studies.

Cook, W. J.

1973-01-01

299

Can the Infrared Radiation that Causes the Enhanced Greenhouse Effect Be Put to Better Use?  

NASA Astrophysics Data System (ADS)

Increasing levels of certain greenhouse gases (GHGs), most importantly CO2 in the earths atmosphere, lead to climate change and global warming as a result of these gases interacting with thermal infrared (TIR) radiation from earth to space. Here, the option of modifying this radiation is analyzed which would result in modified TIR radiation that would interact less with atmospheric CO2. This alleviates the enhanced greenhouse effect, and at the same time would allow for energy recovery as heat and/or power. Power production is, of course, limited by thermodynamics Second Law. It is shown that various options exist for TIR radiation modification which may be used to generate temperature gradients or temperature differences between volumes of (gases containing) CO2 of sufficient optical thickness. This may be further exploited for power generation: a first, simple case shows power generation of ~1 W per m2 surface at a Carnot efficiency of ~7%, using the sky and ground level surroundings as heat reservoirs.

Zevenhoven, Ron

2008-08-01

300

C-Field Methods for Non-Equilibrium Bose Gases  

NASA Astrophysics Data System (ADS)

We review c-field methods for simulating the non-equilibrium dynamics of degenerate Bose gases beyond the mean-field Gross-Pitaevskii approximation. We describe three separate approaches that utilise similar numerical methods, but have distinct regimes of validity. Systems at finite temperature can be treated with either the closed-system projected Gross-Pitaevskii equation (PGPE), or the open-system stochastic projected Gross-Pitaevskii equation (SPGPE). These are both applicable in quantum degenerate regimes in which thermal fluctuations are significant. At low or zero temperature, the truncated Wigner projected Gross Pitaevskii equation (TWPGPE) allows for the simulation of systems in which spontaneous collision processes seeded by quantum fluctuations are important. We describe the regimes of validity of each of these methods, and discuss their relationships to one another, and to other simulation techniques for the dynamics of Bose gases. The utility of the SPGPE formalism in modelling non-equilibrium Bose gases is illustrated by its application to the dynamics of spontaneous vortex formation in the growth of a Bose-Einstein condensate.

Davis, Matthew J.; Wright, Tod M.; Blakie, P. Blair; Bradley, Ashton S.; Ballagh, Rob J.; Gardiner, Crispin W.

2013-02-01

301

FTIR spectroscopy for the determination of water in corrosive gases  

SciTech Connect

Internal corrosion in semiconductor gas delivery systems may lead to increased particle counts in downstream fabrication tools and to catastrophic failure of the delivery system itself. The problem is particularly acute since, once the corrosion begins, it becomes a moisture reservoir to further damage the system. To keep gas systems as moisture free as possible semiconductor manufacturers employ drying filters, usually located just after the source of the process gas. Even so, the piping for corrosive gases may need to be rebuilt every few years. Careful monitoring of the moisture in the process gases can provide valuable information about the state of the gas handling system and its effect on the process integrity. Presently there are several technologies costing $50K or less that are capable of detecting trace water vapor as low as 50 ppb in N{sub 2}. However, no one type of instrument has achieved universal acceptance. In particular, all have limited compatibility with corrosive gases such as HCl and HBr. The goal of this project is to develop an in-line instrument based on infrared spectroscopy for this purpose. Earlier results leave no doubt that FTIR spectroscopy can be successfully used for trace water detection. However, important questions regarding optimal data analysis and instrument design are not yet fully answered. It is the goal of this research effort to answer these questions and to incorporate the findings into a prototype device suitable for commercialization.

Rowe, R.K.; Stallard, B.R. [Sandia National Labs., Albuquerque, NM (United States); Espinoza, L.H.; Niemczyk, T.M. [New Mexico Univ., Albuquerque, NM (United States). Dept. of Chemistry

1994-07-01

302

Biogenic and anthropogenic trace gases in the atmosphere  

NASA Technical Reports Server (NTRS)

This paper illustrates the importance of biogenic and anthropogenic trace gases for the global environment and for the climate system. The paper briefly reviews the currently available estimates of sources and strengths of the biogenic and anthropogenic gases on the global scale. One of the major concerns for the global environment is the rapid increase in the concentration of long-lived trace gases such as CO2, CH4, N2O and the chlorofluorocarbons. The trend in the carbon dioxide concentration, as a result of fossil-fuel burning, is of the order of 0.4 percent per year, and this trend is related to the CO2 uptake by the ocean and by terrestrial ecosystems, which are likely to be modified if the planet warms up in the forthcoming decades. The concentrations of methane and nitrous oxide are increasing by 0.9 and 0.25 percent per year, respectively. In the case of the most widely used chlorofluorocarbons, trends as large as 10 percent per year or more are being measured.

Brasseur, G. P.; Prinn, R. G.

1992-01-01

303

Air Pollution, Greenhouse Gases and Climate Change  

NASA Astrophysics Data System (ADS)

The global build up of greenhouse gases (GHGs), is the most significant environmental issue facing the planet. GHGs warm the surface and the atmosphere with significant implications for, rainfall, retreat of glaciers and sea ice, sea level, among other factors. What is less recognized, however, is a comparably major global problem dealing with air pollution. Until about ten years ago, air pollution was thought to be just an urban or a local problem. But new data have revealed that, due to fast long range transport, air pollution is transported across continents and ocean basins, resulting in trans-oceanic and trans-continental plumes of atmospheric brown clouds (ABCs) containing sub micron size particles, i.e, aerosols. ABCs intercept sunlight by absorbing as well as reflecting it, both of which lead to a large surface dimming. The dimming effect is enhanced further because aerosols nucleate more cloud drops which makes the clouds reflect more solar radiation. While the solar heating at the surface is reduced by aerosols in ABCs, the atmospheric solar heating increases due to soot solar absorption. The net difference between the dimming and the atmospheric solar heating is estimated be negative which contributes to a global cooling effect. The global cooling from this negative ABC forcing may have masked as much as 50% of the warming due to GHGs. We will identify regional and mega-city hot spots of ABCs. Long range transport from these hot spots gives rise to wide spread plumes over the adjacent oceans. Such a pattern of regionally concentrated surface dimming and atmospheric solar heating, accompanied by wide spread dimming over the oceans, gives rise to large regional effects. Only during the last decade, we have begun to comprehend the surprisingly large regional impacts. The large north-south gradient in the ABC dimming has altered the north-south gradients in sea surface temperatures, which in turn has been shown by models to decrease rainfall over the continents. The uncertainties in our understanding of the ABC effects are large, but we are discovering new ways in which human activities are changing the climate and the environment.

Ramanathan, V.

2007-12-01

304

Gases as Idealized Lattices: A Rational Reconstruction of Students' Understanding of the Behavior of Gases.  

ERIC Educational Resources Information Center

Establishes a relationship between students' understanding of gases and its parallels in the history of science. Finds that college freshman students' alternative conceptions about gas behavior are resistant to change and recapitulate theories scientists held in the past, such as the Lattice Theory of Gases. (Contains 52 references.) (Author/WRM)

Niaz, Mansoor

2000-01-01

305

Condensate fluctuations of interacting Bose gases within a microcanonical ensemble  

NASA Astrophysics Data System (ADS)

Based on counting statistics and Bogoliubov theory, we present a recurrence relation for the microcanonical partition function for a weakly interacting Bose gas with a finite number of particles in a cubic box. According to this microcanonical partition function, we calculate numerically the distribution function, condensate fraction, and condensate fluctuations for a finite and isolated Bose-Einstein condensate. For ideal and weakly interacting Bose gases, we compare the condensate fluctuations with those in the canonical ensemble. The present approach yields an accurate account of the condensate fluctuations for temperatures close to the critical region. We emphasize that the interactions between excited atoms turn out to be important for moderate temperatures.

Wang, Jianhui; He, Jizhou; Ma, Yongli

2011-05-01

306

In-situ infrared detection of stack gases  

NASA Astrophysics Data System (ADS)

Infrared measurement using gas-filter correlation (GFC) detection offers an accurate, sensitive, and highly selective technique for the quantitative detection of a number of common industrial gases. A radiative transfer model based on the HITRAN database has been developed to permit the response function of such an instrument to be calculated. The model has been applied to a number of gases, calculating the instrument response to both the target gas and selected interferent species over a broad range of stack temperatures. An optical probe GFC detector has been designed for in-stack measurements of CO and HCl from incinerators and thermal power stations. The probe can be purged with clean air for a true baseline check and a calibration chamber is provided which allows the instrument to be calibrated using bottled gas mixtures. The instrument has completed a successful plant trial during which it measured CO emissions from a coal-fired power station, showing a detection sensitivity of 5 ppm. Detection of HCl has also been demonstrated in the laboratory.

Stuart, Derek D.

1993-03-01

307

Density Fluctuations in Uniform Quantum Gases  

SciTech Connect

Analytical expressions are given for the static structure factor S(k) and the pair correlation function g(r) for uniform ideal Bose-Einstein and Fermi-Dirac gases for all temperatures. In the vicinity of Bose Einstein condensation (BEC) temperature, g(r) becomes long ranged and remains so in the condensed phase. In the dilute gas limit, g(r) of bosons and fermions do not coincide with Maxwell-Boltzmann gas but exhibit bunching and anti-bunching effect respectively. The width of these functions depends on the temperature and is scaled as {radical}(inverse atomic mass). Our numerical results provide the precise quantitative values of suppression/increase (antibunching and bunching) of the density fluctuations at small distances in ideal quantum gases in qualitative agreement with the experimental observation for almost non-trapped dilute gases.

Bosse, J. [Institute for Theoretical Physics, Freie Universitaet Berlin (Germany); Pathak, K. N. [Department of Physics, Panjab University, Chandigarh (India); Singh, G. S. [Department of Physics, Indian Institute of Technology, Roorkee (India)

2011-12-12

308

Where do California's greenhouse gases come from?  

SciTech Connect

Last March, more than two years after California passed legislation to slash greenhouse gas emissions 25 percent by 2020, Lawrence Berkeley National Laboratory scientist Marc Fischer boarded a Cessna loaded with air monitoring equipment and crisscrossed the skies above Sacramento and the Bay Area. Instruments aboard the aircraft measured a cocktail of greenhouse gases: carbon dioxide from fossil fuel use, methane from livestock and landfills, CO2 from refineries and power plants, traces of nitrous oxide from agriculture and fuel use, and industrially produced other gases like refrigerants. The flight was part of the Airborne Greenhouse Gas Emissions Survey, a collaboration between Berkeley Lab, the National Oceanic and Atmospheric Administration, and the University of California, and UC Davis to pinpoint the sources of greenhouse gases in central California. The survey is intended to improve inventories of the states greenhouse gas emissions, which in turn will help scientists verify the emission reductions mandated by AB-32, the legislation enacted by California in 2006.

Fischer, Marc

2009-01-01

309

Where do California's greenhouse gases come from?  

ScienceCinema

Last March, more than two years after California passed legislation to slash greenhouse gas emissions 25 percent by 2020, Lawrence Berkeley National Laboratory scientist Marc Fischer boarded a Cessna loaded with air monitoring equipment and crisscrossed the skies above Sacramento and the Bay Area. Instruments aboard the aircraft measured a cocktail of greenhouse gases: carbon dioxide from fossil fuel use, methane from livestock and landfills, CO2 from refineries and power plants, traces of nitrous oxide from agriculture and fuel use, and industrially produced other gases like refrigerants. The flight was part of the Airborne Greenhouse Gas Emissions Survey, a collaboration between Berkeley Lab, the National Oceanic and Atmospheric Administration, and the University of California, and UC Davis to pinpoint the sources of greenhouse gases in central California. The survey is intended to improve inventories of the states greenhouse gas emissions, which in turn will help scientists verify the emission reductions mandated by AB-32, the legislation enacted by California in 2006.

Fischer, Marc

2013-05-29

310

Rare gases in cyclosilicates and cogenetic minerals  

NASA Technical Reports Server (NTRS)

The cyclosilicate minerals, beryl, tourmaline, and cordierite, typically contain large amounts of He-4 and Ar-40 which are not in situ radiogenic products. In the study of excess rare gases in cyclosilicates, one of the most enigmatic observations is the age effect, a qualitative tendency for geologically older samples to contain more excess He-4 and Ar-40 than younger samples. The present investigation is concerned with measurements regarding the abundance and isotopic composition of all five rare gases in a number of cyclosilicates as well as in their cogenetic minerals. The significance of the obtained data is discussed. The data indicate that cyclosilicates sample the rare gases present in the environment in which they crystallize. This 'sampling' involves major elemental fractionations which are variable but mineral specific. Cyclosilicates can, therefore, be used to probe the isotopic ratios and elemental compositions.

Saito, K.; Alexander, E. C., Jr.; Dragon, J. C.; Zashu, S.

1984-01-01

311

Managing biogeochemical cycles to reduce greenhouse gases  

SciTech Connect

This special issue focuses on terrestrial biogeochemical cycles as they relate to North America-wide budgeting and future projection of biogenic greenhouse gases (GHGs). Understanding the current magnitude and providing guidance on the future trajectories of atmospheric concentrations of these gases requires investigation of their (i) biogeochemical origins, (ii) response to climate feedbacks and other environmental factors, and (iii) susceptibility to management practices. This special issue provides a group of articles that present the current state of continental scale sources and sinks of biogenic GHGs and the potential to better manage them in the future.

Post, Wilfred M [ORNL; Venterea, Rodney [United States Department of Agriculture (USDA), Agricultural Research Service (ARS), Soil and Water

2012-01-01

312

Measuring Viscosities of Gases at Atmospheric Pressure  

NASA Technical Reports Server (NTRS)

Variant of general capillary method for measuring viscosities of unknown gases based on use of thermal mass-flowmeter section for direct measurement of pressure drops. In technique, flowmeter serves dual role, providing data for determining volume flow rates and serving as well-characterized capillary-tube section for measurement of differential pressures across it. New method simple, sensitive, and adaptable for absolute or relative viscosity measurements of low-pressure gases. Suited for very complex hydrocarbon mixtures where limitations of classical theory and compositional errors make theoretical calculations less reliable.

Singh, Jag J.; Mall, Gerald H.; Hoshang, Chegini

1987-01-01

313

Stationary light in cold-atomic gases  

SciTech Connect

We discuss stationary light created by a pair of counterpropagating control fields in {lambda}-type atomic gases with electromagnetically induced transparency for the case of negligible Doppler broadening. In this case, the secular approximation used in the discussion of stationary light in hot vapors is no longer valid. We discuss the quality of the effective light-trapping system and show that in contrast to previous claims it is finite even for vanishing ground-state dephasing. The dynamics of the photon loss is in general nonexponential and can be faster or slower than in hot gases.

Nikoghosyan, Gor [Fachbereich Physik and Research Center OPTIMAS, Universitaet Kaiserslautern, Erwin-Schroedinger-Strasse, D-67663 Kaiserslautern (Germany); Institute of Physical Research, 378410 Ashtarak-2 (Armenia); Fleischhauer, Michael [Fachbereich Physik and Research Center OPTIMAS, Universitaet Kaiserslautern, Erwin-Schroedinger-Strasse, D-67663 Kaiserslautern (Germany)

2009-07-15

314

PREFACE: The 27th International Conference on Phenomena in Ionized Gases (ICPIG)  

NASA Astrophysics Data System (ADS)

The 27th International Conference on Phenomena in Ionized Gases (ICPIG) was held in the conference resort of NH Koningshof in Veldhoven, near Eindhoven, The Netherlands, 17-22 July 2005. ICPIG is an important biennial event at which academics and industrialists working in low-temperature plasma science can meet. The 27th ICPIG was organized under the sponsorship of the International Union of Pure and Applied Chemistry (IUPAP), the Royal Dutch Academy of Sciences (KNAW), the Research School Centre for Plasma Physics and Radiation Technology (CPS), the Dutch Organization for Fundamental Research on Matter (FOM), Stichting Physica, the Dutch organization for Scientific Research (NWO), Philips Lighting, and the Eindhoven University of Technology. The scientific scope of this joint conference focused on both experimental and theoretical aspects of the physics of ionized gases as well as on industrial applications. It covered the following topics: • Kinetics, thermodynamics and transport phenomena • Elementary processes • Low-pressure glows • Coronas, sparks, surface discharges and high-pressure glows • Arc discharges • High-frequency discharges • Ionospheric, magnetospheric and astrophysical plasmas • Plasma diagnostic methods • Plasma wall interaction, electrode and surface effects • Physical aspects of plasma chemistry, plasma processing of surfaces and thin film technology • The generation and dynamics of plasma flows • Non-ideal plasmas, clusters and dusty plasmas • Waves and instabilities, including shock waves • Nonlinear phenomena, self-organization and chaos • Particle and laser beam interaction with plasmas • Plasma sources of radiation • Numerical modelling • Plasmas for environmental issues • Highly ionized, low-pressure plasmas (plasma thrusters, ion sources and surface treatment) • High-pressure, non-thermal plasmas. ICPIG was attended by close to 400 scientists from 41 countries. A selection of the invited papers is published in this special issue. The 401 contributed papers were presented in five poster sessions. The abstracts of all the oral and poster contributions were published in the CD of the conference proceedings. I would like to thank all members of the Local Organizing Committee as well as the members of the International Scientific Committee of ICPIG for their indispensable contributions to the success of this joint meeting. We are particularly grateful to the Editor-in-Chief of Plasma Sources Science and Technology, Professor Noah Hershkowitz, for the opportunity to publish the invited papers in this special issue and so bring the 27th ICPIG to a wider audience.

Kroesen, Gerrit

2006-05-01

315

Infrared band absorptance correlations and applications to nongray radiation. [mathematical models of absorption spectra for nongray atmospheres in order to study air pollution  

NASA Technical Reports Server (NTRS)

Various mathematical models for infrared radiation absorption spectra for atmospheric gases are reviewed, and continuous correlations for the total absorptance of a wide band are presented. Different band absorptance correlations were employed in two physically realistic problems (radiative transfer in gases with internal heat source, and heat transfer in laminar flow of absorbing-emitting gases between parallel plates) to study their influence on final radiative transfer results. This information will be applied to the study of atmospheric pollutants by infrared radiation measurement.

Tiwari, S. N.; Manian, S. V. S.

1976-01-01

316

Climate change and trace gases.  

PubMed

Palaeoclimate data show that the Earth's climate is remarkably sensitive to global forcings. Positive feedbacks predominate. This allows the entire planet to be whipsawed between climate states. One feedback, the 'albedo flip' property of ice/water, provides a powerful trigger mechanism. A climate forcing that 'flips' the albedo of a sufficient portion of an ice sheet can spark a cataclysm. Inertia of ice sheet and ocean provides only moderate delay to ice sheet disintegration and a burst of added global warming. Recent greenhouse gas (GHG) emissions place the Earth perilously close to dramatic climate change that could run out of our control, with great dangers for humans and other creatures. Carbon dioxide (CO2) is the largest human-made climate forcing, but other trace constituents are also important. Only intense simultaneous efforts to slow CO2 emissions and reduce non-CO2 forcings can keep climate within or near the range of the past million years. The most important of the non-CO2 forcings is methane (CH4), as it causes the second largest human-made GHG climate forcing and is the principal cause of increased tropospheric ozone (O3), which is the third largest GHG forcing. Nitrous oxide (N2O) should also be a focus of climate mitigation efforts. Black carbon ('black soot') has a high global warming potential (approx. 2000, 500 and 200 for 20, 100 and 500 years, respectively) and deserves greater attention. Some forcings are especially effective at high latitudes, so concerted efforts to reduce their emissions could preserve Arctic ice, while also having major benefits for human health, agricultural productivity and the global environment. PMID:17513270

Hansen, James; Sato, Makiko; Kharecha, Pushker; Russell, Gary; Lea, David W; Siddall, Mark

2007-07-15

317

Increased soil emissions of potent greenhouse gases under increased atmospheric CO2  

NASA Astrophysics Data System (ADS)

Increasing concentrations of atmospheric carbon dioxide (CO2) can affect biotic and abiotic conditions in soil, such as microbial activity and water content. In turn, these changes might be expected to alter the production and consumption of the important greenhouse gases nitrous oxide (N2O) and methane (CH4) (refs 2, 3). However, studies on fluxes of N2O and CH4 from soil under increased atmospheric CO2 have not been quantitatively synthesized. Here we show, using meta-analysis, that increased CO2 (ranging from 463 to 780 parts per million by volume) stimulates both N2O emissions from upland soils and CH4 emissions from rice paddies and natural wetlands. Because enhanced greenhouse-gas emissions add to the radiative forcing of terrestrial ecosystems, these emissions are expected to negate at least 16.6 per cent of the climate change mitigation potential previously predicted from an increase in the terrestrial carbon sink under increased atmospheric CO2 concentrations. Our results therefore suggest that the capacity of land ecosystems to slow climate warming has been overestimated.

van Groenigen, Kees Jan; Osenberg, Craig W.; Hungate, Bruce A.

2011-07-01

318

Increased soil emissions of potent greenhouse gases under increased atmospheric CO2.  

PubMed

Increasing concentrations of atmospheric carbon dioxide (CO(2)) can affect biotic and abiotic conditions in soil, such as microbial activity and water content. In turn, these changes might be expected to alter the production and consumption of the important greenhouse gases nitrous oxide (N(2)O) and methane (CH(4)) (refs 2, 3). However, studies on fluxes of N(2)O and CH(4) from soil under increased atmospheric CO(2) have not been quantitatively synthesized. Here we show, using meta-analysis, that increased CO(2) (ranging from 463 to 780 parts per million by volume) stimulates both N(2)O emissions from upland soils and CH(4) emissions from rice paddies and natural wetlands. Because enhanced greenhouse-gas emissions add to the radiative forcing of terrestrial ecosystems, these emissions are expected to negate at least 16.6 per cent of the climate change mitigation potential previously predicted from an increase in the terrestrial carbon sink under increased atmospheric CO(2) concentrations. Our results therefore suggest that the capacity of land ecosystems to slow climate warming has been overestimated. PMID:21753852

van Groenigen, Kees Jan; Osenberg, Craig W; Hungate, Bruce A

2011-07-14

319

The Continual Intercomparison of Radiation Codes (CIRC) Assessing Anew the Quality of GCM Radiation Algorithms  

NASA Technical Reports Server (NTRS)

The simulation of changes in the Earth's climate due to solar and thermal radiative processes with global climate models (GCMs) is highly complex, depending on the parameterization of a multitude of nonlinearly coupled physical processes. In contrast, the germ of global climate change, the radiative forcing from enhanced abundances of greenhouse gases, is relatively well understood. The impressive agreement between detailed radiation calculations and highly resolved spectral radiation measurements in the thermal infrared under cloudless conditions (see, for example, Fig. 1) instills confidence in our knowledge of the sources of gaseous absorption. That the agreement spans a broad range of temperature and humidity regimes using instruments mounted on surface, aircraft, and satellite platforms not only attests to our capability to accurately calculate radiative fluxes under present conditions, but also provides confidence in the spectroscopic basis for computation of fluxes under conditions that might characterize future global climate (e.g., radiative forcing). Alas, the computational costs of highly resolved spectral radiation calculations cannot be afforded presently in GCMs. Such calculations have instead been used as the foundation for approximations implemented in fast but generally less accurate algorithms performing the needed radiative transfer (RT) calculations in GCMs. Credible climate simulations by GCMs cannot be ensured without accurate solar and thermal radiative flux calculations under all types of sky conditions: pristine cloudless, aerosol-laden, and cloudy. The need for accuracy in RT calculations is not only important for greenhouse gas forcing scenarios, but is also profoundly needed for the robust simulation of many other atmospheric phenomena, such as convective processes.

Oreopoulos, Lazaros; Mlawer, Eli

2010-01-01

320

Atmospheric Radiation Measurement Climate Research Facility (ACRF) Annual Report 2008  

SciTech Connect

The Importance of Clouds and Radiation for Climate Change: The Earth’s surface temperature is determined by the balance between incoming solar radiation and thermal (or infrared) radiation emitted by the Earth back to space. Changes in atmospheric composition, including greenhouse gases, clouds, and aerosols, can alter this balance and produce significant climate change. Global climate models (GCMs) are the primary tool for quantifying future climate change; however, there remain significant uncertainties in the GCM treatment of clouds, aerosol, and their effects on the Earth’s energy balance. In 1989, the U.S. Department of Energy (DOE) Office of Science created the Atmospheric Radiation Measurement (ARM) Program to address scientific uncertainties related to global climate change, with a specific focus on the crucial role of clouds and their influence on the transfer of radiation in the atmosphere. To reduce these scientific uncertainties, the ARM Program uses a unique twopronged approach: • The ARM Climate Research Facility, a scientific user facility for obtaining long-term measurements of radiative fluxes, cloud and aerosol properties, and related atmospheric characteristics in diverse climate regimes; and • The ARM Science Program, focused on the analysis of ACRF and other data to address climate science issues associated with clouds, aerosols, and radiation, and to improve GCMs. This report provides an overview of each of these components and a sample of achievements for each in fiscal year (FY) 2008.

LR Roeder

2008-12-01

321

Production of quantum-degenerate strontium gases  

NASA Astrophysics Data System (ADS)

We report on an improved scheme to generate Bose-Einstein condensates (BECs) and degenerate Fermi gases of strontium. This scheme allows us to create quantum gases with higher atom number, a shorter time of the experimental cycle, or deeper quantum degeneracy than before. We create a BEC of 84Sr exceeding 107 atoms, which is a 30-fold improvement over previously reported experiments. We increase the atom number of 86Sr BECs to 2.5×104 (a fivefold improvement) and refine the generation of attractively interacting 88Sr BECs. We present a scheme to generate 84Sr BECs with a cycle time of 2 s. We create deeply degenerate 87Sr Fermi gases with T/TF as low as 0.10(1), where the number of populated nuclear spin states can be set to any value between one and ten. Furthermore, we report on a total of five different double-degenerate Bose-Bose and Bose-Fermi mixtures. These studies prepare an excellent starting point for applications of strontium quantum gases anticipated in the near future.

Stellmer, Simon; Grimm, Rudolf; Schreck, Florian

2013-01-01

322

Interaction of Gases with Ionic Substrates.  

National Technical Information Service (NTIS)

The interaction of non-polar gases such as Ar, Kr and N2 with homogeneous samples of NaCl, RbF, NH4I, BN and copper single crystals have been investigated. Samples of NaCl and NH4I of unusual homogeneity have been prepared and characterized as have been s...

B. W. Davis R. A. Pierotti

1972-01-01

323

Behavior of Gases: Disaster at Lake Nyos  

NSDL National Science Digital Library

Students, through discussion and structured inquiry, will learn about the behavior of gases under various conditions. Students will be able to apply these concepts to everyday objects such as soda bottles, fire extinguishers, hot air balloons, propane tanks, and aerosol products.

Wilk, Bryan

2012-07-13

324

Toxicity of pyrolysis gases from foam plastics  

NASA Technical Reports Server (NTRS)

Twenty-three samples of flexible foams and twelve samples of rigid foams were evaluated for toxicity of pyrolysis gases, using the USF toxicity screening test method. Polychloroprene among the flexible foams, and polystyrene among the rigid foams, appeared to exhibit the least toxicity under these particular test conditions.

Hilado, C. J.; Cumming, H. J.; Casey, C. J.

1980-01-01

325

Measurement of volume and flow in gases  

Microsoft Academic Search

The measurement of volume and flow of the gases which are used during anaesthesia and in the intensive care environment is standard in modern anaesthesia practice. This is done using both electronic and non-electronic equipment. It is essential to have a thorough understanding of the basic principles of the measurement techniques used in these pieces of equipment. This is necessary

Nanda Gopal Mandal

2009-01-01

326

Desulfurization of fuel gases. Executive summary.  

National Technical Information Service (NTIS)

The objective of this work was to demonstrate that solid solutions of cerium oxide (CeO(sub 2)) and other altervalent oxides (doped CeO(sub 2)) were capable of removing more H(sub 2)S from fuel gases than Ceo(sub 2) without any dopant. The ability of undo...

1991-01-01

327

Ratio of Specific Heats of Gases  

NSDL National Science Digital Library

Students bounce a steel ball in a gas-filled tube. The compressed gas provides a restoring force on the ball. By measuring the distance of initial fall or the frequency of oscillation, the ratio of specific heats of several gases, Cp/Cv may be determined.

2009-02-16

328

Noble Gases in Carbonatite Magmatism: Oldonyo Lengai  

Microsoft Academic Search

Oldonyo Lengai,Tanzania, is the only volcano on Earth that is actively erupting carbonatitic lavas. In order to further constrain the origin of the Oldonyo Lengai magmas, an expedition to Oldonyo Lengai in July 2005 sampled to volcanic gases. Two fumaroles were sampled, one with a discharging temperature of 124 °C, the other more than 168 °C. The chemical composition of

P. Burnard; B. Marty; T. Fischer; D. Hilton; F. Mangasini; C. Makene

2006-01-01

329

Refractive Indices of Gases at Microwave Frequencies  

ERIC Educational Resources Information Center

Describes a simple microwave interferometer capable of measuring small phase shifts. Proposes laboratory exercises involving the use of the interferometer in the determination of refractive indices of gases and the analysis of the reflection in a test chamber. (Author/CP)

Goodhead, D. T.; And Others

1976-01-01

330

Removing Sulphur Dioxide From Stack Gases  

ERIC Educational Resources Information Center

Process types, process concepts, claims and counterclaims, cost factors, and the level of developed technology for sulfur dioxide control in stack gases are focused upon and evaluated. Wet and dry processes as well as recovery and throwaway processes are compared. (BL)

Slack, A. V.

1973-01-01

331

Noble Gases in Five Rumuruti Chondrites  

NASA Astrophysics Data System (ADS)

Concentration and isotopic composition have been measured in five new R-chondrites: Dar al Gani 417, Northwest Africa 053, Ouzina, Sahara 98248, and Sahara 99531. Two of these meteorites contain solar trapped gases, NWA 053 has an unusual short exposure age of 0.2 Ma.

Weber, H. W.; Schultz, L.

2001-03-01

332

On waves in nonadiabatic and nonequilibrium gases  

Microsoft Academic Search

The propagation of the waves (including relaxation, pressure, and density waves) and thermal modes in nonadiabatic and nonequilibrium gases are discussed. Based on the mechanism of thermal disturbance feedback, a new governing equation for the propagation of disturbances and the dispersion relation is obtained. Some new conclusions are reached. For example, the disturbance is either purely growing or slowly damped

K. Zhi; L. Wen-Qiang

1984-01-01

333

Thermodesorption of Gases from Various Vacuum Materials.  

National Technical Information Service (NTIS)

A number of materials are commonly used as vacuum system walls. The desorption of gases from these materials may contribute significantly to the internal pressure of an unpumped device or to the gas load which a pump must handle in a dynamic system. This ...

L. C. Beavis

1979-01-01

334

Scissors Mode of Trapped Dipolar Gases  

NASA Astrophysics Data System (ADS)

We study the scissors modes of dipolar boson and fermion gases trapped in a spherically symmetric potential. We use the harmonic oscillator states to solve the time-dependent Gross-Pitaevskii equation for bosons and the time-dependent Hartree-Fock equation for fermions. It is pointed out that the scissors modes of bosons and fermions can be of quite different nature.

Tohyama, Mitsuru

2010-11-01

335

Interaction of carbonaceous materials with gunpowder gases  

Microsoft Academic Search

We have investigated the completeness of the interaction of various carbonaceous materials with gunpowder gases in the ballistite gunpowder combustion wave. We have shown that the limit in the carbonaceous material content, above which a change occurs in the interaction of the CM with the gunpowder combustion products, depends on the material's specific surface and is independent of the oxidizer-excess

A. P. Denisyuk; Yu. G. Shepelev

1989-01-01

336

Computing land use emissions of greenhouse gases  

Microsoft Academic Search

A model has been developed to estimate the regional emission of greenhouse gases from land-use related sources. Driving forces for this model are the changing regional demand for food and wood products driven by demographic and economic developments (Zuidema et al., 1994). To include the environmental conditions, which are essential factors determining the flux for certain sources, emissions are grid-based

G. J. J. Kreileman; A. F. Bouwman

1994-01-01

337

Reducing greenhouse gases: Promoting an international accord  

Microsoft Academic Search

This article reports on a Cornell Center for the Environmental sponsored workshop to explore the prospects for reducing atmospheric concentrations of greenhouse gases, carbon dioxide as well as others through voluntary, market-based international accords. Cornell specialists in a range of fields were joined by participants from other universities and policy groups. The topics discussed covered the threat to the biosphere,

Schuler

2009-01-01

338

Diminishable\\/removable sources of greenhouse gases  

Microsoft Academic Search

To the purpose of a balanced, comprehensive approach to reducing and eliminating emissions of greenhouse gases, a list of their diminishable\\/removable sources has been worked out. This list cannot be complete and the authors expect it to provoke discussion in professional magazines and that this list will be expanded and modified.

Milan Vondruska; Vratislav Bednarik

2009-01-01

339

Voluntary Reporting of Greenhouse Gases, 2002.  

National Technical Information Service (NTIS)

The Voluntary Reporting of Greenhouse Gases Program, required by Section 1605(b) of the Energy Policy Act of 1992, records the results of voluntary measures to reduce, avoid, or sequester greenhouse gas emissions. A total of 228 U.S. companies and other o...

2004-01-01

340

Voluntary Reporting of Greenhouse Gases 2003.  

National Technical Information Service (NTIS)

The Energy Policy Act of 1992 (EPACT) directed the U.S. Department of Energy (DOE), with the Energy Information Administration (EIA) as the implementing agency, to develop a program to document voluntary actions that reduce emissions of greenhouse gases o...

2005-01-01

341

Fullerenes and the Nature of Planetary Gases  

NASA Technical Reports Server (NTRS)

Over the past several decades, two issues have dominated the discussion of planetary noble gas patterns: 1) the general resemblance of the noble gas abundances in carbonaceous chondrites to those measured in the Earth s atmosphere and; 2) atmospheric inventories of argon and neon that fall off significantly with increasing distance from the Sun. The recognition of the latter has led to the conclusion that the planetary component is not found on planets. In particular, the inability to explain the missing xenon reservoir, once thought to be sequestered in crustal rocks has been extremely troublesome. Some models have focused on various fractionations of solar wind rather than condensation as the process for the evolution of noble gases in the terrestrial planets. However, these models cannot explain the observed gradient of the gases, nor do they account for the similar Ne/Ar ratios and the dissimilar planetary Ar/Kr ratios. More recent studies have focused on hydrodynamic escape to explain the fractionation of gases, like neon, in the atmosphere and the mantle. Escape theory also seems to explain, in part, the isotopically heavy argon on Mars, however, it does not explain the discrepancies observed for the abundances of argon and neon on Venus and the Earth. This has led to the assumption that some combination of solar wind implantation, absorption and escape are needed to explain the nature of planetary noble gases.

Becker, Luann; Poreda, Robert J.; Nuth, Joe

2003-01-01

342

Electron-atom collisions in gases  

NASA Astrophysics Data System (ADS)

Electron-atom collisions in gases are an aspect of atomic physics. Three experiments in this field employing a thyratron are described: (i) the Ramsauer-Townsend effect, (ii) the excitation and ionization potentials of xenon and (iii) the ion-electron recombination after interrupting the electric discharge.

Kraftmakher, Yaakov

2013-11-01

343

Capturing shock waves in inelastic granular gases  

Microsoft Academic Search

Shock waves in granular gases generated by either a vertically vibrated granular layer or by hitting an obstacle at rest are treated by means of a shock capturing scheme that approximates the Euler equations of granular gas dynamics with an equation of state (EOS), introduced by Goldshtein and Shapiro ( J. Fluid Mech. 282 (1995) 75), that takes into account

Susana Serna; Antonio Marquina

2004-01-01

344

Connecting Chemical Dynamics in Gases and Liquids  

Microsoft Academic Search

Modern ultrafast spectroscopic techniques provide new opportunities to study chemical reaction dynamics in liquids and hold the possibility of obtaining much of the same detailed information available in gases. Vibrational energy transfer studies are the most advanced of the investigations and demonstrate that it is possible to observe state-specific pathways of energy flow within a vibrationally excited molecule (intramolecular vibrational

Christopher G. Elles; F. Fleming Crim

2006-01-01

345

Optical properties of explosive-driven shock waves in noble gases  

SciTech Connect

High explosives have been used to shock-heat rare gases to brightness temperatures up to 36,000/sup 0/K, with large radiating areas. Temperatures were determined from radiometer signals at both 280 and 520 nm. Shock velocities up to 9 mm/..mu..s were used in both plane and cyclindrical geometries. Neon, argon, krypton, and xenon gases at atmospheric initial pressure were examined in plane shocks. Using argon, the effects of increased initial pressure were studied. For cylindrical shock expansion in argon, brightness temperatures were measured over a range of shock velocities from 3 to 9 mm/..mu..s. Up to 4% of the explosive energy was emitted as radiation. The shock waves are found to be reasonable approximations to blackbodies.

Jones, C.R.; Davis, W.C.

1983-01-01

346

Emission factors of hydrocarbons, halocarbons, trace gases and particles from biomass burning in Brazil  

Microsoft Academic Search

Airborne measurements of the emissions of gases and particles from 19 individual forest, cerrado, and pasture fires in Brazil were obtained during the Smoke, Clouds, and Radiation-Brazil (SCAR-B) study in August-September 1995. Emission factors were determined for a number of major and minor gaseous and particulate species, including carbon dioxide, carbon monoxide, sulfur dioxide, nitrogen oxides, methane, nonmethane hydrocarbons, halocarbons,

Ronald J. Ferek; Jeffrey S. Reid; Peter V. Hobbs; Donald R. Blake; Catherine Liousse

1998-01-01

347

Greenhouse gases and future long?term changes in the stratospheric temperature and the ozone layer  

Microsoft Academic Search

A numerical two?dimensional (2D) interactive dynamical–radiative–photochemical model including aerosol physics is used to examine the expected long?term changes in stratospheric temperature and the Earth's ozone layer due to anthropogenic pollution of the atmosphere by the greenhouse gases CO2, CH4 and N2O. The model time?dependent runs were made for the period from 1975 to 2050. The results of the calculations show

I. G. Dyominov; A. M. Zadorozhny

2008-01-01

348

Tested Demonstrations: Diffusion of Gases--Kinetic Molecular Theory of Gases.  

ERIC Educational Resources Information Center

Provided are procedures and list of materials needed to demonstrate that the pressure inside a container with a porous surface can be changed due to the rate of diffusion of low molecular weight gases. Typical results obtained are included. (JN)

Gilbert, George L., Ed.

1984-01-01

349

Encapsulation of Gases in Zeolite 3A and Temperature Programmed Desorption of the Trapped Gases  

Microsoft Academic Search

Gases (Ar, N? and CO?) were encapsulated in zeolite 3A at high temperature (350ºC) and pressure (maximum pressure obtained from a gas cylinder). Temperature programmed desorption (TPD), with a linear temperature schedule, was applied to study the kinetics of the release of the trapped gases. The TPD spectra for argon show two peaks ( a large peak at about 350ºC

Yun-cheung Chan

1976-01-01

350

Global radiative forcing from contrail cirrus  

NASA Astrophysics Data System (ADS)

Aviation makes a significant contribution to anthropogenic climate forcing. The impacts arise from emissions of greenhouse gases, aerosols and nitrogen oxides, and from changes in cloudiness in the upper troposphere. An important but poorly understood component of this forcing is caused by `contrail cirrus'--a type of cloud that consist of young line-shaped contrails and the older irregularly shaped contrails that arise from them. Here we use a global climate model that captures the whole life cycle of these man-made clouds to simulate their global coverage, as well as the changes in natural cloudiness that they induce. We show that the radiative forcing associated with contrail cirrus as a whole is about nine times larger than that from line-shaped contrails alone. We also find that contrail cirrus cause a significant decrease in natural cloudiness, which partly offsets their warming effect. Nevertheless, net radiative forcing due to contrail cirrus remains the largest single radiative-forcing component associated with aviation. Our findings regarding global radiative forcing by contrail cirrus will allow their effects to be included in studies assessing the impacts of aviation on climate and appropriate mitigation options.

Burkhardt, Ulrike; Kärcher, Bernd

2011-04-01

351

Relative Toxicity of Gases From Overheating of Rubbers and Plastics  

Microsoft Academic Search

Rubber and plastic materials may produce toxic gases when overheated to the point of decomposition. This paper reviews and discusses the available data on the relative toxicity of these pyrolysis gases.

Carlos J. Hilado; Nancy V. Huttlinger

1980-01-01

352

40 CFR 86.1214-85 - Analytical gases.  

Code of Federal Regulations, 2010 CFR

... (a) Analyzer gases. (1) Gases for the hydrocarbon analyzer shall...consisting of a blend of nitrogen and oxygen with oxygen concentrations between 18 and 21...devices to obtain the required analyzer gas concentrations is allowable...

2010-07-01

353

Supersonic Minimum Length Nozzle Design for Dense Gases.  

National Technical Information Service (NTIS)

Recently, dense gases have been investigated for many engineering applications such as for turbomachinery and wind tunnels. Supersonic nozzle design for these gases is complicated by their nonclassical behavior in the transonic flow regime. In this paper ...

A. C. Aldo B. M. Argrow

1993-01-01

354

The Physiological Effects of Argon, Helium and the Rare Gases.  

National Technical Information Service (NTIS)

The report describes some physiologic effects of helium, neon, argon, krypton, xenon, and of several other normally chemically inert gases such as nitrogen. The observations show that chemically inert gases are endowed with molecular properties which enab...

H. R. Schreiner

1965-01-01

355

Noble Gases in a Heterogeneous, Dynamic Mantle  

NASA Astrophysics Data System (ADS)

The source of unradiogenic noble gases in oceanic basalts has been perhaps the most enigmatic aspect of mantle geochemistry. One popular hypothetical source, a large enriched layer deep in the mantle, is incompatible with geophysical evidence. Not only does seismic tomography preclude a separate lower mantle, but any such layer ought to generate mantle plumes, and associated hotspot swells, much stronger than those observed. The only layering compatible with geophysical evidence is the D” region, which is only around 200 km thick and comprises only about 2% of the mantle’s mass. It is argued that when the major-element heterogeneity of the mantle is more fully considered the noble gas observations can be reconciled with a mantle structure compatible with geophysics and dynamics. The mantle is observed, and expected, to comprise a refractory peridotite matrix containing eclogites and pyroxenites that are more fusible and more enriched in incompatible elements. These heterogeneities will melt deeper, and not all of their off-axis melt will be extracted at mid-ocean ridges, so it will recirculate internally within the mantle. Such recirculated heterogeneities will retain their incompatible elements, and the incompatibles will become concentrated within them, probably from early in Earth history. The heterogeneities, more mafic than ultramafic, will tend to be denser than average mantle through most of the mantle’s depth. They will therefore tend to accumulate within the D” region, as dynamical models have demonstrated for subducted (mafic) oceanic crust. D” would thus contain a mixture of subducted oceanic crust, which will have been degassed at the surface, and recirculated heterogeneities carrying noble gases. Dynamical models show that residence times in D” are longer than for the mantle interior, so the noble gases in D” would tend to be older, as well as higher in concentration. This can explain why mantle plumes, tapping D”, contain noble gases that are less radiogenic than mid-ocean ridge basalts. Quantitative models bear this out. This picture requires that the bulk of the mantle’s noble gases reside in the MORB source, which comprises most of the mantle. Recent estimates of MORB source composition may have underestimated the content of incompatible elements because they are tied to peridotite compositions, which will probably not have equilibrated with all of the incompatibles residing in fusible heterogeneities. Most estimates of MORB source composition also focus on so-called “normal” MORB, which is actually more depleted than the mean. When more enriched components and plume-related components are considered, the budgets of the noble gases can be plausibly accounted for.

Davies, G. F.

2010-12-01

356

Indirect radiative forcing efficiencies of spatially resolved aerosol and precursor gas emissions  

NASA Astrophysics Data System (ADS)

Linking indirect radiative forcing to aerosol and precursor gas emissions clarifies an important pathway by which anthropogenic emissions affect climate through tropospheric chemistry. Cloud condensation nuclei (CCN) concentrations and meteorological conditions at droplet activation height modulate the cloud droplet number concentration (CDNC); with greater CDNC, clouds reflect sunlight more effectively. CCN concentrations are perturbed not only by direct aerosol emissions but also by tropospheric chemical interactions of precursor gases. The short-lived nature of aerosol and their radiative effects underscores the importance of spatial specificity when attributing forcing to emissions. Here, we evaluate the relative influence of emissions on radiative forcing in a computationally efficient manner; the method is extensible to future climatic conditions where the efficiencies may be modified due to changes in tropospheric chemical composition or meteorological conditions. We present indirect radiative forcing efficiencies of spatially refined aerosol and precursor gas emissions. The GEOS-Chem adjoint (Henze et al., 2007) coupled with the adjoint of a droplet activation parameterization (Karydis et al., 2012) calculates the relative influence of aerosol and precursor gas emissions on CDNC. Uncertainty due to the prescribed droplet activation height is explored. Modulation of radiative forcing by CDNC is determined by the Linearized Discrete Ordinate Radiative Transfer (LIDORT) model (Spurr, 2008). These novel quantities are compared with the aerosol direct radiative forcing efficiencies of Henze et al. (2012). Quantifying radiative efficiencies of aerosol and precursor gas emissions provides environmental decision makers an estimate of climate forcing expected due to moderate emissions perturbations possible with policy changes.

Capps, S. L.; Henze, D. K.; Karydis, V.; Russell, A. G.; Nenes, A.

2013-12-01

357

Method for enhancing microbial utilization rates of gases using perfluorocarbons  

DOEpatents

A method of enhancing the bacterial reduction of industrial gases using perfluorocarbons (PFCs) is disclosed. Because perfluorocarbons (PFCs) allow for a much greater solubility of gases than water does, PFCs have the potential to deliver gases in higher concentrations to microorganisms when used as an additive to microbial growth media thereby increasing the rate of the industrial gas conversion to economically viable chemicals and gases.

Turick, Charles E. (Idaho Falls, ID)

1997-01-01

358

Laser cooling by collisional redistribution of radiation  

Microsoft Academic Search

The general idea that optical radiation may cool matter was put forward 80 years ago. Doppler cooling of dilute atomic gases is an extremely successful application of this concept. More recently, anti-Stokes cooling in multilevel systems has been explored, culminating in the optical refrigeration of solids. Collisional redistribution of radiation has been proposed as a different cooling mechanism for atomic

Ulrich Vogl; Martin Weitz

2009-01-01

359

Coherent detection of pulsed narrowband terahertz radiation  

Microsoft Academic Search

We demonstrate the generation and coherent detection of narrowband terahertz radiation using a Q-switched laser pumped optical parametric oscillator as the optical source. Narrowband terahertz radiation is produced using conventional difference frequency mixing and coherently detected via a frequency domain technique that relies on coherent upconversion of the terahertz field combined with optical homodyning to suppress background noise. GaSe crystals

Hua Cao; Ajay Nahata

2006-01-01

360

Parallels between Adolescents' Conception of Gases and the History of Chemistry.  

ERIC Educational Resources Information Center

Discusses the need to consider students' pre-existing conceptual schemes when teaching chemistry. Reports on a study done in Spain which indicates that the existence of adolescents preconceptions about gases is important to consider when teaching the principles of conservation of substance, mass, and weight. (TW)

Mas, Carlos J. Furio; And Others

1987-01-01

361

Mechanisms controlling the global oceanic distribution of the inert gases argon, nitrogen and neon  

Microsoft Academic Search

Dissolved inert gas measurements in the ocean yield important information about processes that occur during water mass formation. We present argon, nitrogen, and neon data from the subtropical and subpolar North Pacific and the subtropical North Atlantic. All three gases were supersaturated at the surface. In the deep ocean, Ar and N2 were undersaturated while Ne re- mained supersaturated. All

Roberta C. Hamme; Steven R. Emerson

2002-01-01

362

Conduction model for the thermal influence of lithic clasts in mixtures of hot gases and ejecta  

Microsoft Academic Search

The thermal influence of lithic clasts in mixtures of hot gases and ejecta produced during explosive eruptions is an important aspect of the dynamics of eruption columns and pyroclastic flows. In order to study this aspect we present a heat conduction model, which considers both the temperature distribution of the lithic clasts and the exchange of thermal energy between the

J. Marti; J. L. Diez-Gil; R. Ortiz

1991-01-01

363

Air pollution, greenhouse gases and climate change: Global and regional perspectives  

Microsoft Academic Search

Greenhouse gases (GHGs) warm the surface and the atmosphere with significant implications for rainfall, retreat of glaciers and sea ice, sea level, among other factors. About 30 years ago, it was recognized that the increase in tropospheric ozone from air pollution (NOx, CO and others) is an important greenhouse forcing term. In addition, the recognition of chlorofluorocarbons (CFCs) on stratospheric ozone

V. Ramanathan; Y. Feng

2009-01-01

364

On the evaluation of halocarbon radiative forcing and global warming potentials  

SciTech Connect

Net global warming potentials and instantaneous radiative forcing values that include the cooling from halocarbon-induced ozone destruction have been calculated for 14 of the most significant halocarbons. These calculations were performed by incorporating knowledge of direct global warming potentials with an evaluation of the relationship between tropospheric cooling from stratospheric ozone loss and tropospheric halocarbon mixing ratios. The indirect cooling effect is strongly dependent upon the effectiveness of each halocarbon for ozone destruction. Strong net cooling is ascribed to additions of bromocarbon gases, while methyl chloroform and carbon tetrachloride are more nearly climate-neutral, and the chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) display strong net warming. Consideration of indirect cooling also has important implications for the expected future net halocarbon forcing of the climate system: in the next 20 years, halocarbon radiative forcing is not predicted to decrease as mixing ratios of strongly ozone-depleting gases decline because of faster decreases in radiative cooling than in radiative warming. Furthermore, continuing production of HFCs as substitutes for CFCs could result in sharply increasing halocarbon radiative heating in the latter part of the 21st century because of the increasing atmospheric burden of these compounds.

Daniel, J.S.; Solomon, S.; Albritton, D.L. [Univ. of Colorado, Boulder, CO (United States)] [Univ. of Colorado, Boulder, CO (United States); [NOAA, Boulder, CO (United States)

1995-01-01

365

40 CFR 86.514-78 - Analytical gases.  

Code of Federal Regulations, 2013 CFR

... CONTROL OF EMISSIONS FROM NEW AND IN-USE HIGHWAY VEHICLES AND ENGINES Emission Regulations for 1978 and Later New Motorcycles; Test Procedures § 86.514-78 Analytical gases. (a) Analyzer gases. (1) Gases for the CO and CO2...

2013-07-01

366

Process for removing sulfur dioxide from flue gases  

Microsoft Academic Search

This patent describes an improvement in a dry process for the removal of sulfur dioxide from flue gases by the addition thereto of hydrated lime containing sugar in a coal combustion unit, wherein the flue gases result from the combustion of a coal in a combustion chamber, and the flue gases are treated in an electrostatic precipitator prior to discharge

M. W. Jr

1989-01-01

367

Detection of sulfur-containing gases by MODIS  

Microsoft Academic Search

Gases are one of quite difficult environmental factor to treat. They are obstruction in humans life because they have amorphous shape and the are invisible. Additionally, some gases have no smell. Especially, generation of toxic gas near volcano and industrial waste processing facilities, is closely related to our life. These gases are hitherto detected on site survey by gas detection

Yoshimine Tanabu; Takanori Sasaki; Tomohisa Takasugi; Shigetaka Fujita

2009-01-01

368

BIOMASS BURNING AND THE PRODUCTION OF GREENHOUSE GASES  

Microsoft Academic Search

Biomass burning is a source of greenhouse gases, carbon dioxide, methane, and nitrous oxide. In addition, biomass burning is a source of chemically active gases, including carbon monoxide, nonmethane hydrocarbons, and nitric oxide. These gases, along with methane, lead to the chemical production of tropospheric ozone (another greenhouse gas) as well as control the concentration of the hydroxyl radical, which

Joel S. Levine

369

Thermodynamics of Quantum Gases for the Entire Range of Temperature  

ERIC Educational Resources Information Center

We have analytically explored the thermodynamics of free Bose and Fermi gases for the entire range of temperature, and have extended the same for harmonically trapped cases. We have obtained approximate chemical potentials for the quantum gases in closed forms of temperature so that the thermodynamic properties of the quantum gases become…

Biswas, Shyamal; Jana, Debnarayan

2012-01-01

370

Chamber for Continuous Mixing of High Pressure Combustible Gases  

Microsoft Academic Search

A small mixing chamber has been developed for continuous mixing of combustible gases for use in the combustion driver of a hypersonic shock tunnel. The gases are mixed while passing through the chamber and then flow directly into the shock tunnel driver tube. The system ensures immediate uniform mixing of the gases. It eliminates all waiting time needed to allow

Richard A. Oman; Jarvis Leng

1964-01-01

371

Microwave limb sounder. [measuring trace gases in the upper atmosphere  

NASA Technical Reports Server (NTRS)

Trace gases in the upper atmosphere can be measured by comparing spectral noise content of limb soundings with the spectral noise content of cold space. An offset Cassegrain antenna system and tiltable input mirror alternately look out at the limb and up at cold space at an elevation angle of about 22. The mirror can also be tilted to look at a black body calibration target. Reflection from the mirror is directed into a radiometer whose head functions as a diplexer to combine the input radiation and a local ocillator (klystron) beam. The radiometer head is comprised of a Fabry-Perot resonator consisting of two Fabry-Perot cavities spaced a number of half wavelengths apart. Incoming radiation received on one side is reflected and rotated 90 deg in polarization by the resonator so that it will be reflected by an input grid into a mixer, while the klystron beam received on the other side is also reflected and rotated 90 deg, but not without passing some energy to be reflected by the input grid into the mixer.

Gustincic, J. J. (inventor)

1981-01-01

372

Supercontinuum generation in gases: A high order nonlinear optics phenomenon  

SciTech Connect

The recent development of high power, ultrashort pulse sources has created renewed interest in the interaction between intense laser radiation and free atoms and molecules. Not only is it feasible to apply laser fields that approach, or exceed, the strength of the atomic field as seen by the outer electrons, but it is also possible to apply these fields nonadiabatically using ultrashort pulses. Until now, experiments have been restricted to isolated atoms. However, because the theories of nonlinear optics and multiphoton ionization are so interrelated, we should expect these new phenomena to have optical signatures. In addition to their intrinsic interest, nonlinear optics experiments can add a new perspective for judging emerging theories of high intensity laser processes. Clearly, there is a new class of experiments to be performed using ultrahigh power, ultrashort pulses. We describe an experiment performed in high pressure gases with a 2 psec or 70 fsec 0.6 {mu}m pulse focused to a peak intensity of I {approx lt} 10{sup 13} W/cm{sup 2}. The maximum intensity exceeds that in which multiphoton ionization is observed in longer pulse experiments in Xe using either 1.06 {mu}m or 0.53 {mu}m radiation. It is approximately the intensity at which tunnel ionization is observed with nanosecond 10 {mu}m pulses in very low pressure Xe. Furthermore, at such intensities in 0.53 {mu}m and 1.06 {mu}m experiments, high energy electrons are observed from Xe.

Corkum, P.B.; Rolland, C. (National Research Council of Canada, Ottawa, ON (Canada)); Srinivasan-Rao, T. (Brookhaven National Lab., Upton, NY (USA))

1986-01-01

373

Underground Nuclear Explosions and Release of Radioactive Noble Gases  

NASA Astrophysics Data System (ADS)

Over a period in 1961-1990 496 underground nuclear tests and explosions of different purpose and in different rocks were conducted in the Soviet Union at Semipalatinsk and anovaya Zemlya Test Sites. A total of 340 underground nuclear tests were conducted at the Semipalatinsk Test Site. One hundred seventy-nine explosions (52.6%) among them were classified as these of complete containment, 145 explosions (42.6%) as explosions with weak release of radioactive noble gases (RNG), 12 explosions (3.5%) as explosions with nonstandard radiation situation, and four excavation explosions with ground ejection (1.1%). Thirty-nine nuclear tests had been conducted at the Novaya Zemlya Test Site; six of them - in shafts. In 14 tests (36%) there were no RNG release. Twenty-three tests have been accompanied by RNG release into the atmosphere without sedimental contamination. Nonstandard radiation situation occurred in two tests. In incomplete containment explosions both early-time RNG release (up to ~1 h) and late-time release from 1 to 28 h after the explosion were observed. Sometimes gas release took place for several days, and it occurred either through tunnel portal or epicentral zone, depending on atmospheric air temperature.

Dubasov, Yuri V.

2010-05-01

374

Equation of state for detonation product gases  

NASA Astrophysics Data System (ADS)

Based on the empirical linear relationship between detonation velocity and loading density, an approximate description for the Chapman-Jouguet (CJ) state for detonation product gases has been presented. Assuming that the Grüneisen parameter is a function only of volume, we obtained the Grüneisen parameter along CJ states. Thermodynamic identity between the Grüneisen parameter and another non-dimensional material parameter R used in the Rice-Walsh type equation of state introduced by Wu and Jing can be used to derive the enthalpy-pressure-volume equation of state for detonation gases. Behavior of this parameter R as a function of pressure is calculated and revealed that their change with pressure is very gradual and seems to approach a finite value with decreasing pressure. Release isentropes from CJ states of several initial density detonation of PETN is shown.

Nagayama, K.; Kubota, S.

2014-05-01

375

Itinerant ferromagnetism in ultracold Fermi gases  

SciTech Connect

Itinerant ferromagnetism in cold Fermi gases with repulsive interactions is studied applying the Jastrow-Slater approximation generalized to finite polarization and temperature. For two components at zero temperature, a second-order transition is found at ak{sub F}{approx_equal}0.90 compatible with results of quantum-Monte-Carlo (QMC) calculations. Thermodynamic functions and observables, such as the compressibility and spin susceptibility and the resulting fluctuations in number and spin, are calculated. For trapped gases, the resulting cloud radii and kinetic energies are calculated and compared to recent experiments. Spin-polarized systems are recommended for effective separation of large ferromagnetic domains. Collective modes are predicted and tricritical points are calculated for multicomponent systems.

Heiselberg, H. [Applied Research, DALO, Lautrupbjerg 1-5, DK-2750 Ballerup (Denmark)

2011-05-15

376

Bose Einstein Condensation of Ideal Bose Gases  

NASA Astrophysics Data System (ADS)

Bose Einstein condensation (BEC) is studied for ideal boson gases with a wide class of the dispersion relations. A criterion of the BEC, the transition temperature and a fraction of the condensate are calculated under the appropriate thermodynamic limits. The correspondence between the dispersion relation (spectrum) and the trap potential is shown. This gives the criterion for the trap shape and the dimensionality of the system.

Ieda, Jun'ichi; Tsurumi, Takeya; Wadati, Miki

2001-05-01

377

Exciton states in solid rare gases  

Microsoft Academic Search

The problem of the exciton states in solid rare gases is studied within the framework of the integral-equation approach appropriate for intermediate-coupling interaction. The different contributions appearing in the integral equation are investigated and related to physical quantities by means of an analysis of their behavior in the two limiting situations in which the effective-mass approximation (EMA) or the atomic

L. Resca; S. Rodriguez

1978-01-01

378

Toxicity of Pyrolysis Gases from Elastomers  

NASA Technical Reports Server (NTRS)

The toxicity of the pyrolysis gases from six elastomers was investigated. The elastomers were polyisoprene (natural rubber), styrene-butadiene rubber (SBR), ethylene propylene diene terpolymer (EPDM), acrylonitrile rubber, chlorosulfonated polyethylene rubber, and polychloroprene. The rising temperature and fixed temperature programs produced exactly the same rank order of materials based on time to death. Acryltonitrile rubber exhibited the greatest toxicity under these test conditions; carbon monoxide was not found in sufficient concentrations to be the primary cause of death.

Hilado, Carlos J.; Kosola, Kay L.; Solis, Alida N.; Kourtides, Demetrius A.; Parker, John A.

1977-01-01

379

Interaction of scandium dideuteride with reactive gases  

Microsoft Academic Search

Thin films of scandium dideuteride have been thermally cycled in vacuum to determine the specific reactions that occur with the residual gases of the vacuum. The thickness of the films, expressed as areal density, was nominally at 1.5 mg\\/cm². The data indicate the film activates at 648 K as evidenced by rapid oxygen depletion from the surface. Upon activation of

D. M. Holloway; W. E. Jr. Swartz

1977-01-01

380

Removing arsenic from copper smelter gases  

Microsoft Academic Search

The pyrometallurgical processing of nonferrous minerals found in association with sulfur and arsenic generates arsenic-bearing\\u000a SO2 gases. Effective process gas cleaning presents technical problems due to the high volatility of the As2O3 compound and the elevated dew point of the sulfur-trioxidecontaining SO2 gas. Critical factors for gascleaning technology selection pertaining to technical feasibility, economic acceptability, and\\u000a environmental compatibility are the

Frank Dalewski

1999-01-01

381

Reservoir storage and containment of greenhouse gases  

Microsoft Academic Search

This paper deals with the problem of disposal of industrial waste greenhouse gases (CO2) into deep reservoirs. The simulator TOUGH2 was used to model the injection of 100 kg\\/s of CO2 for 10 years into an aquifer 3 km deep with the object of evaluating the long-term storage prospects for this gas. Depending on the permeability structure above the injection

Graham J. Weir; Stephen P. White; Warwick M. Kissling

1996-01-01

382

The ice record of greenhouse gases  

Microsoft Academic Search

Gases trapped in polar ice provide our most direct record of the changes in greenhouse gas levels during the past 150,000 years. The best conducted trace-gas records are for CO2 and CH4. The measurements corresponding to the industrial period document the recent changes in growth rate. The variability observed over the last 1000 years constrains the possible feedbacks of a

D. Raynaud; J. Jouzel; J. M. Barnola; J. Chappellaz; R. J. Delmas; C. Lorius

1993-01-01

383

Shock waves, implosions and dusty gases  

Microsoft Academic Search

Progress in analytical, numerical, and experimental research on shock waves, implosions, and dusty gases at the University of Toronto Institute for Aerospace Studies is reviewed. Solutions for the laminar compressible dusty-gas boundary layer over a semi-infinite flat plate were obtained, as well as that for the complementary boundary layer induced by a moving shock in a dusty-gas tube. Numerical studies

I. I. Glass; D.-L. Zhang; J. Kaca

1989-01-01

384

Splitting of inviscid fluxes for real gases  

NASA Technical Reports Server (NTRS)

Flux-vector and flux-difference splittings for the inviscid terms of the compressible flow equations are derived under the assumption of a general equation of state for a real gas in equilibrium. No necessary assumptions, approximations or auxiliary quantities are introduced. The formulas derived include several particular cases known for ideal gases and readily apply to curvilinear coordinates. Applications of the formulas in a TVD algorithm to one-dimensional shock-tube and nozzle problems show their quality and robustness.

Liou, Meng-Sing; Vanleer, Bram; Shuen, Jian-Shun

1988-01-01

385

Desulfurization process for hydrogen sulfide containing gases  

Microsoft Academic Search

A desulfurization process for hydrogen sulfide-containing gases, which comprises contacting an alkaline aqueous medium containing a naphthoquinone sulfonate, a water-soluble compound of at least one polyvalent metal selected from the group consisting of iron, manganese, vanadium and copper, and a water-soluble high molecular compound having weight-average molecular weight of from 300 to 50,000 with a hydrogen sulfide-containing gas thereby causing

T. Sonoda; T. Kaziwara; T. Sato; F. Shimoyama

1984-01-01

386

Experimental studies concerning the drying of voloxidizer off-gases  

SciTech Connect

The results of an experimental program conducted to aid in the design of a tritium retention system to remove tritiated water from voloxidizer off-gases are presented. The retention system is expected to be a fixed-bed adsorption unit using a commercially available desiccant, such as molecular sieves, to dry the off-gases. The presence of iodine in the off-gas stream somewhat complicates the drying process since some iodine will be retained in the drying bed along with the tritiated water. The present work represents a follow-up to a study in which a small-scale (2-in.-diam by 30-in.-long) packed column of Linde Molecular Sieves (LMS) type 3A was repeatedly loaded and regenerated using a non-radioactive simulated voloxidizer off-gas containing water and iodine vapor. Both water and iodine loadings were measured and the regeneration characteristics of the bed were observed. The following studies were carried out: (1) testing of other desiccants showed LMS type 3A to be superior because of its high water loading and low iodine retention; (2) development of a column-mounted moisture detector; (3) adsorption isotherms; (4) iodine analysis using a commercial oxidant monitor; (5) tests on cartridge-type beds - a series of tests were conducted using three small drying beds connected in series. One further finding of this study was the importance of the clay binder (used in pelletized molecular sieves) in obtaining satisfactory or acceptably low iodine retention.

Holland, W.D.; Shah, A.H.; Kaiser, A.F.; McGee, J.C.

1981-07-01

387

Indoor exposures to fine aerosols and acid gases.  

PubMed Central

Indoor exposures to aerosols and gases are associated with both indoor and outdoor air pollution sources. The identification of sources and the assessment of their relative contribution can be a complicated process due to a) the presence of numerous indoor sources, which can vary from building to building; b) the uncertainties associated with the estimation of the impact of outdoor sources on indoor air quality; c) the interactions between pollutants; and d) the importance of reactions between pollutants and indoor surfaces. It is well established that fine particles (diameter less than or equal to 2.5 microns) originating from outdoor sources such as automobiles, oil and coal combustion, incineration, and diverse industrial activities can penetrate into the indoor environment. Indoor/outdoor ratios, usually varying between 0.4 and 0.8, depend on parameters such as particle size and density, air exchange rate, and the surface-to-volume ratio of the indoor environment. Determining fine particle elemental composition makes it possible to identify the contribution of different outdoor sources. This paper focuses on the origin and the concentration of indoor aerosols and acid gases by highlighting the results from two indoor air quality studies.

Koutrakis, P; Brauer, M; Briggs, S L; Leaderer, B P

1991-01-01

388

Unconventional ordering in correlated Fermi liquids and gases  

NASA Astrophysics Data System (ADS)

In this thesis I study the roles of magnetic and superconducting phenomena in strongly correlated electron systems. Much of the focus is on the coexistence of ferromagnetism and superconductivity which has only been experimentally observed in the last five years. Therefore, most of the theoretical work presented here is directed towards elucidating the current experiments and predicting the results of future ones. I will review the history of this rich field in both theoretical and experimental frameworks, and try to cast light on the various viewpoints that are held with respect to the phenomenon of coexistent superconductivity and ferromagnetism. In that regard, I will argue that a theory based on s-wave superconductivity is quite relevant and explains several important experiments, and cannot be discounted from explaining several more, particularly in the case of the well-studied material UGe2. The theoretical foundation used in this thesis to examine UGe 2, in particular Fermi liquid theory, is then applied to the intriguing ultracold Fermi gases. These materials are quite rich experimentally, and the fundamental quantum physics that they display, such as matter waves and Bose-Einstein condensation, is amenable to theoretical calculations. The results of the study of these gases in our model will be shown to agree very well with many of the experimental observations that have until now not been understood thoroughly.

Jackiewicz, Jason

389

Evaluation of radiation scheme performance within chemistry climate models  

NASA Astrophysics Data System (ADS)

This paper evaluates global mean radiatively important properties of chemistry climate models (CCMs). We evaluate stratospheric temperatures and their 1980-2000 trends, January clear sky irradiances, heating rates, and greenhouse gas radiative forcings from an offline comparison of CCM radiation codes with line-by-line models, and CCMs' representation of the solar cycle. CCM global mean temperatures and their change can give an indication of errors in radiative transfer codes and/or atmospheric composition. Biases in the global temperature climatology are generally small, although five out of 18 CCMs show biases in their climatology that likely indicate problems with their radiative transfer codes. Temperature trends also generally agree well with observations, although one model shows significant discrepancies that appear to be due to radiation errors. Heating rates and estimated temperature changes from CO2, ozone, and water vapor changes are generally well modeled. Other gases (N2O, CH4, and CFCs) have only played a minor role in stratospheric temperature change, but their heating rates have large fractional errors in many models. Models that do not account for variations in the spectrum of solar irradiance cannot properly simulate solar-induced variations in stratospheric temperature. The combined long-lived greenhouse gas global annual mean instantaneous net radiative forcing at the tropopause is within 30% of line-by-line models for all CCM radiation codes tested. Problems remain in simulating radiative forcing for stratospheric water vapor and ozone changes with errors between 3% and 200% compared to line by line models. The paper makes recommendations for CCM radiation code developers and future intercomparisons.

Forster, Piers M.; Fomichev, Victor I.; Rozanov, Eugene; Cagnazzo, Chiara; Jonsson, Andreas I.; Langematz, Ulrike; Fomin, Boris; Iacono, Michael J.; Mayer, Bernhard; Mlawer, Eli; Myhre, Gunnar; Portmann, Robert W.; Akiyoshi, Hideharu; Falaleeva, Victoria; Gillett, Nathan; Karpechko, Alexey; Li, Jiangnan; Lemennais, Perrine; Morgenstern, Olaf; OberläNder, Sophie; Sigmond, Michael; Shibata, Kiyotaka

2011-05-01

390

Methane hydrates as potential energy resource: Part 1 – Importance, resource and recovery facilities  

Microsoft Academic Search

Gas hydrates are ice-like crystalline solids that form from mixtures of water and light natural gases such as methane, carbon dioxide, ethane, propane and butane. Methane was the dominant component among other hydrocarbon gases in the sediments. Gas hydrates, potentially one of the most important energy resources for the future. Methane gas hydrates are increasingly considered a potential energy resource.

Ayhan Demirbas

2010-01-01

391

Why Are Teams Important?  

NASA Video Gallery

Kelvin Kirby, deputy director for the Center for Radiation Engineering and Science for Space Exploration, or CRESSE, at Prairie View A&M University, explains how the complexity of space radiation m...

392

Inspection of non-CO 2 greenhouse gases from emission sources and in ambient air by Fourier-transform-infrared-spectrometry: Measurements with FTIS-MAPS  

Microsoft Academic Search

Infrared spectrometry is a versatile basis to analyse greenhouse gases in the atmosphere. A multicomponent air pollution software (MAPS) was developed for retrieval of gas concentrations from radiation emission as well as absorption measurements. Concentrations of CO, CH4, N2O, and H2O as well as CO2, NO, NO2, NH3, SO2, HCl, HCHO, and the temperature of warm gases are determined on-line.

Klaus Schäfer; Rainer Haus; Jörg Heland

1994-01-01

393

CO2 retrieval algorithm for the thermal infrared spectra of the Greenhouse Gases Observing Satellite: Potential of retrieving CO2 vertical profile from high-resolution FTS sensor  

Microsoft Academic Search

The Greenhouse Gases Observing Satellite (GOSAT) was successfully launched in January 2009, with the aim of providing global observations of greenhouse gases. We developed an algorithm to retrieve CO2 vertical profiles from the terrestrial radiation spectra at 700–800 cm?1 and assessed its validity. For this purpose, we first computed GOSAT pseudomeasurement spectra and then performed CO2 retrieval simulations using the

Naoko Saitoh; Ryoichi Imasu; Yoshifumi Ota; Yosuke Niwa

2009-01-01

394

Nadir Sounding of Carbon Gases using SCIAMACHY Near Infrared Channels  

NASA Astrophysics Data System (ADS)

The Beer InfraRed Retrieval Algorithm (BIRRA) and Column EstimatoR Vertical InfraRed Sounding Atmosphere (CERVISA) codes have been designed to retrieve vertical column den-sities (VCDs) of atmospheric gases in the near and thermal infrared (NIR,TIR) region of the electromagnetic spectrum by means of non-linear least squares fitting of radiances. As part of the operational SCIAMACHY level 1-2 processor, BIRRA is currently used for the specific retrieval of carbon monoxide (CO) VCDs exploiting the fitting window 4282-4301 cm-1 within the SCIAMACHY channel 8. Using appropriate fitting windows in channel 6, BIRRA also allows to gain information on greenhouse gases such as methane and carbon dioxide. Unfortunately, the increasing number of dead and bad pixels -specially in the NIR channels -reduces the available spectral information and consequently makes the VCDs retrieval more and more challenging. The proper choice of the pixel mask, fitting window, auxiliary fit parameters, as well as the filtering of the Level 2 data is crucial for obtaining a high quality atmospheric product. For validation of BIRRA the closely related CERVISA code is used to retrieve CO and CH4 from nadir infrared sounding data of AIRS, IASI, or TES. BIRRA and CERVISA share a large portion of modules, e.g., for line-by-line absorption and the nonlinear least squares solver; the essential difference is the part of the forward model devoted to radiative transfer through the atmosphere, i.e., Beer's law for the NIR versus Schwarzschild's equation for the TIR. CERVISA retrieval results are compared both to the operational products of the TIR sounder and to the SCIAMACHY-BIRRA product. In this work, we present recent results of carbon monoxide and methane retrievals.

Gimeno García, Sebastián; Schreier, Franz; Lichtenberg, Günter; Slijkhuis, Sander; Hess, Michael; Aberle, Bernd

395

On-line measurements of halogenated greenhouse gases for allocation of European sources  

NASA Astrophysics Data System (ADS)

Halocarbons are important atmospheric trace gases, which contribute to the green-house effect and some of which are also responsible for destruction of stratospheric ozone (e.g. CFCs, halones). Emissions of halocarbons are therefore regulated through international treaties like the Montreal and Kyoto Protocol, which regulate their industrial usage according to their properties. In Europe these substances are measured within the EU-project SOGE at four back-ground sites (Jungfraujoch, Mace Head, Spitzbergen, Monte Cimone). Data of these measurements are used to allocate potent European source regions and estimate European source strengths of these gases. For example, analyses of the 3 years of data will be shown in order to estimate emissions of the Montreal regulated methyl chloroform as well as dominant source regions of the Kyoto Protocol regulated hy-drofluorocarbons. This system of ground-based measurements has the potential to be used as a verifi-cation tool for European emisions of these greenhouse gases.

Reimann, S.; Schaub, D.; Stemmler, K.; Simmonds, P.; O'Doherty, S.; Greally, B.; Stordal, F.; Schmidbauer, N.; Maione, M.

2003-04-01

396

Linear Stability Analysis and Boundary Layer Fluxes of Trace Gases and Aerosols  

NASA Astrophysics Data System (ADS)

One of the important factors that drive the characteristics of local meteorological phenomena is the vertical transport of turbulent kinetic energy from the earth's surface to higher layers within the troposphere. The instability-induced upward dispersion of turbulence increases the vertical ascension of eddy viscosity and introduces additional Reynold's stresses that affect gradients in the atmosphere, which ultimately controls the heating/cooling rates within different layers. Turbulent kinetic energy can also be introduced within the atmosphere due to vertical shears, which generate vorticity. The relative effects of the buoyancy due to instability and vertical shear are quantified by the Richardson number. Radiosonde data were obtained to extract temperature profiles for various times over a fixed region and used as input to a linear stability analysis. The Boussinesq approximation was also applied where the effects of density between layers was disregarded except for buoyancy. The hydrodynamic linear stability analysis was performed with the appropriate set of boundary conditions. The computed eigenvalues are associated with the amplification rates of normal modes of disturbances embedded in the troposphere, which through momentum exchange encourage instabilities to grow and spread vertically. Distributions of normalized perturbation frequencies associated with disturbances were generated and a frequency-averaged amplification rate was computed for each temperature profile. The average amplification rate was used to quantify the strength of the instability and was correlated with a shape factor used to characterize each temperature profile. The fluxes of chemically and radiatively important trace gases and aerosols were determined from the radiosonde data and correlations were made between the out flowing of these influential atmospheric constituents and the shape factors derived from the vertical temperature profiles.

Walker, I. J.; Chakrapani, V.

2006-05-01

397

What Can Ultracold Fermi Gases Teach Us About High Tc Superconductors and Vice Versa?  

ScienceCinema

Studies of superfluidity in ultracold trapped Fermi gases are attracting physicists from a wide range of sub-disciplines including nuclear, condensed matter and particle physics. The excitement in the field is due, in large part, to the remarkable tuneability of these Fermi gases. One can tune the attractive interaction strength continuously from weak to strong (thereby effecting a transition from a BCS to Bose Einstein condensed (BEC) superfluid). One can introduce polarization into the gases at will, which may lead to long-sought-after, but not yet confirmed, exotic superfluid phases. In this talk we discuss the relevance of the cold Fermi gases to other physics subdisciplines. We then summarize how BCS-BEC crossover in the ultracold gases connects with a particularly important topic in condensed matter: high temperature superconductivity. We emphasize some striking similarities relating to the very unusual normal or 'pseudogap' phase of each of the two systems. In the process we give a summary of some of the latest exciting experimental developments in the two fields.

398

What are functional ionic liquids for the absorption of acidic gases?  

PubMed

As a kind of novel and efficient material, ionic liquids (ILs) are used for capture of acidic gases including SO2 and CO2 from flue gas. Due to very low content of acidic gases in flue gas, it is important to find functional ILs to absorb the acidic gases. However, up to now, there is no criterion to distinguish if the ILs are functional or not before use, which greatly influences the design of functional ILs. In this work, a series of ILs were synthesized and used to determine functional or normal ILs for the capture of acidic gases. It has been found that the pKa of organic acids forming the anion of ILs can be used to differentiate functional ILs from normal ILs for the capture of acidic gases from flue gas. If the pKa of an organic acid is larger than that of sulfurous acid (or carbonic acid), the ILs formed by the organic acid can be called functional ILs for SO2 (or CO2) capture, and it can have a high absorption capacity of SO2 (or CO2) with low SO2 (or CO2) concentrations. If not, the IL is just a normal IL. The pKa of organic acids can also be used to explain the absorption mechanism and guide the synthesis of functional ILs. PMID:23360403

Ren, Shuhang; Hou, Yucui; Tian, Shidong; Chen, Xiumei; Wu, Weize

2013-02-28

399

Effects of compressed unsaturated hydrocarbon gases on yeast growth.  

PubMed

The effect of compressed unsaturated hydrocarbon gases on the growth of the yeast Saccharomyces cerevisiae was investigated by microcalorimetry. The growth thermograms showed that unsaturated hydrocarbon gases inhibited yeast growth. As an approach to determining the comparative toxicity of unsaturated hydrocarbon gases, we determined the 50% inhibitory pressure (IP(50)) and the minimum inhibitory pressure (MIP). On the basis of the IP(50) and MIP values, the inhibitory potency of the gases increased in the order ethylene < propylene < 1-butene. Additionally, scanning electron microscopy showed that cells treated with unsaturated hydrocarbon gases were damaged, including invagination of the cell surface. PMID:20233377

Kawachi, Satoshi; Arao, Toshiaki; Suzuki, Yoshihisa; Tamura, Katsuhiro

2010-02-01

400

The state of greenhouse gases in the atmosphere using global observations through 2012  

NASA Astrophysics Data System (ADS)

The Global Atmosphere Watch (GAW) Programme of the World Meteorological Organization (WMO) provides a framework for global observations and assessment of the state and development of atmospheric composition, including greenhouse gases. It puts stringent requirements on the quality of the observations. These requirements are reviewed by the greenhouse gas science and measurement community at biennial WMO/IAEA Meetings on Carbon Dioxide, Other Greenhouse Gases, and Related Tracer Measurement Techniques. The 17th meeting was held in Beijing, China, on 10 - 14 June 2013 (http://ggmt-2013.cma.gov.cn/dct/page/1). Results of global analysis of the observational data are reported annually in the WMO/GAW Annual Greenhouse Gas Bulletin. Bulletin No. 9 represents an update of the results for the year 2012 (extended version is available at http://www.wmo.int/pages/prog/arep/gaw/ghg/ghg9-en-online.html). The cover story of this bulletin presents the attribution of methane sources in the context of the renewed growth of the global average methane mole fraction in 2007. The bulletin is prepared by the WMO/GAW Scientific Advisory Group for Greenhouse Gases (http://www.wmo.int/pages/prog/www/CBS/Lists_WorkGroups/CAS/opag-epac/gaw%20sag%20ghg) in collaboration with the World Data Center for Greenhouse Gases. Observations used for global analysis are collected at more than 100 marine and terrestrial sites worldwide for CO2 and CH4 and at a smaller number of sites for other greenhouse gases. Globally averaged dry-air mole fractions of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) derived from this network reached new highs in 2012, with CO2 at 393.1±0.1 ppm, CH4 at 1819±1 ppb and N2O at 325.1±0.1 ppb. These values constitute 141%, 260% and 120% of pre-industrial (before 1750) levels, respectively. The increase of the annual mean CO2 mole fraction from 2011 to 2012 amounted to 2.2 ppm, which is greater than the average growth rate for the 1990s (~1.5 ppm yr-1) and for the past decade (~2.0 ppm yr-1). The globally averaged CH4 mole fraction increased by 6 ppb from 2011 to 2012. The growth rate of CH4 decreased from ~13 ppb yr-1 during the early 1980s to near zero during 1999-2006. Since 2007, atmospheric CH4 has been increasing again, averaging ~5 ppb yr-1. The growth rate of N2O in 2012 was 0.9 ppb yr-1, which is greater than the average growth rate over the last 10 years (0.75 ppb yr-1). The NOAA Annual Greenhouse Gas Index (AGGI) has been defined as the ratio of total radiative forcing due to long-lived greenhouse gases for any year for which adequate global measurements exist to that which was present in 1990. The AGGI in 2012 was 1.32 (corresponding to 2.87 W m-2 of global radiative forcing, relative to 1750, of all long-lived greenhouse gases). The AGGI indicates an increase in radiative forcing by all long-lived greenhouse gases of 32% since 1990 and of 1.2% from 2011 to 2012, while the radiative forcing by all long-lived greenhouse gases in 2012 corresponded to a CO2-equivalent mole fraction of 475.6 ppm (http://www.esrl.noaa.gov/gmd/aggi).

Tarasova, Oksana; Koide, Hiroshi; Dlugokencky, Edward; Montzka, Stephen A.; Butler, James H.

2014-05-01

401

Greenhouse gases and recovery of the Earth’s ozone layer  

NASA Astrophysics Data System (ADS)

A numerical 2-D zonally averaged dynamical radiative-photochemical model of the ozonosphere including aerosol physics is used to examine the role of the greenhouse gases CO 2, CH 4, and N 2O in the recovery of the Earth's ozone layer after reduction of anthropogenic discharges of chlorine and bromine compounds into the atmosphere. A weakness in efficiencies of all catalytic cycles of the ozone destruction due to cooling of the stratosphere caused by greenhouse gases is shown to be a dominant mechanism of the impact of the greenhouse gases on the ozone layer. Numerical experiments show that the total ozone changes caused by greenhouse gases will be comparable in absolute value with the changes due to chlorine and bromine species in the middle of the 21st century. Continuous anthropogenic growth of CO 2 will lead to a significantly faster recovery of the ozone layer. In this case, the global total ozone in the latitude range from 60°S to 60°N will reach its undisturbed level of 1980 by about 2040. If the CO 2 growth stops, the global total ozone will reach this level only by the end of the century.

Dyominov, Igor G.; Zadorozhny, Alexander M.

402

49 CFR 174.204 - Tank car delivery of gases, including cryogenic liquids.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Tank car delivery of gases, including cryogenic...Gases) Materials § 174.204 Tank car delivery of gases, including cryogenic liquids. (a) A tank car containing Class 2 (gases)...

2013-10-01

403

Interactions between aerosol, water vapor, and solar radiation  

Microsoft Academic Search

A quantitative understanding of how clouds, aerosols and atmospheric gases affect the solar radiation absorbed by earth's climate systems is still largely unknown. This dissertation makes calibrated and precise (<1%) measurements of broadband and spectral solar radiation, and integrates these measurements with state-of-the-art radiative transfer models to clarify the roles of water vapor and aerosols in the solar heating of

William Christopher Conant

2000-01-01

404

Emissions Of Greenhouse Gases From Rice Agriculture  

SciTech Connect

This project produced detailed data on the processes that affect methane and nitrous oxide emissions from rice agriculture and their inter-relationships. It defines the shifting roles and potential future of these gases in causing global warming and the benefits and tradeoffs of reducing emissions. The major results include: 1). Mechanisms and Processes Leading to Methane Emissions are Delineated. Our experiments have tested the standard model of methane emissions from rice fields and found new results on the processes that control the flux. A mathematical mass balance model was used to unravel the production, oxidation and transport of methane from rice. The results suggested that when large amounts of organic matter are applied, the additional flux that is observed is due to both greater production and reduced oxidation of methane. 2). Methane Emissions From China Have Been Decreasing Over the Last Two Decades. We have calculated that methane emissions from rice fields have been falling in recent decades. This decrease is particularly large in China. While some of this is due to reduced area of rice agriculture, the bigger effect is from the reduction in the emission factor which is the annual amount of methane emitted per hectare of rice. The two most important changes that cause this decreasing emission from China are the reduced use of organic amendments which have been replaced by commercial nitrogen fertilizers, and the increased practice of intermittent flooding as greater demands are placed on water resources. 3). Global Methane Emissions Have Been Constant For More Than 20 Years. While the concentrations of methane in the atmosphere have been leveling off in recent years, our studies show that this is caused by a near constant total global source of methane for the last 20 years or more. This is probably because as some anthropogenic sources have increased, others, such as the rice agriculture source, have fallen. Changes in natural emissions appear small. 4). Nitrous Oxide Emissions From Rice Fields Increase as Methane Emissions Drop. Inundated conditions favor anaerobic methane production with high emission rates and de-nitrification resulting in modest nitrous oxide emissions. Under drier conditions such as intermittent flooding, methane emissions fall and nitrous oxide emissions increase. Increased nitrogen fertilizer use increases nitrous oxide emissions and is usually accompanied by reduced organic matter applications which decreases methane emissions. These mechanisms cause a generally inverse relationship between methane and nitrous oxide emissions. Reduction of methane from rice agriculture to control global warming comes with tradeoffs with increased nitrous oxide emissions. 5). High Spatial Resolution Maps of Emissions Produced. Maps of methane and nitrous oxide emissions at a resolution of 5 min × 5 min have been produced based on the composite results of this research. These maps are necessary for both scientific and policy uses.

M. Aslam K. Khalil

2009-07-16

405

Distribution and origin of dissolved gases of groundwaters at Las Cañadas aquifer, Tenerife, Canary Islands  

NASA Astrophysics Data System (ADS)

Volcanic aquifers commonly trap an important fraction of the main soluble components of fluids released from volcanic-hydrothermal system (CO2, SO2, H2S, HCl, HF, etc.). In particular, the interactions between volcanic gases and volcanic aquifers have been studied through hydrogeochemical parameters, as major and minor ions contents and dissolved gases in groundwaters. In the context of hydrogeochemical studies applied to active volcanic areas, studies of dissolved gases species in groundwater could be a useful tool to better understand the subsurface processes as gas-water-rock interaction or to strengthen the geochemical seismic-volcanic surveillance programs. In this work, we report the results of the geochemical characterization of dissolved gases (N2, O2, Ar, CO2, CH4, CO, H2, He, 222Rn, ?13CTDIC) in 96 groundwater samples from Las Cañadas aquifer (around Teide volcano) between May and October, 2006. The main aims of this work are: (1) to determine the background level of magmatic gas input in the aquifer during quiescent periods, (2) to better define the origin of dissolved gases in Las Cañadas aquifer, specially CO2, (3) to evaluate the gas-water-rock interaction processes occurring at depth, and (4) to delineate high permeable pathway of upward migration of volcanic-hydrothermal gases. In general, the dissolved gas phase in groundwaters of Las Cañadas aquifer is relatively enriched in endogenous gases (CO2, He and H2) while it is relatively depleted in atmospheric gases (N2, O2 and Ar). N2-O2-CO2 triangular diagram shows that dissolved gases in most of analyzed groundwater are variable mixtures of CO2-rich fluids from the volcanic-hydrothermal system (as represent the Teide fumaroles) with dissolved air. The relatively high N2/O2 ratio in some groundwater compared to the air saturated water suggests an O2 consumption during gas-water-rock interactions occurring at depth. Spatial distribution maps show anomalous concentration of 222Rn CH4, H2 and CO2 dissolved in groundwater at the westernmost area of Las Cañadas aquifer, which is in good spatial correlation with geophysical and geochemical anomalies related to 2004-2005 seismic-volcanic unrest at Tenerife Island. Determinations of ?13C values in the total dissolved inorganic carbon (TDIC) in groundwater in Las Cañadas aquifer ranging from -5 to +5 (‰ vs PDB). This result was explained by isotopic fractionation of either volcanic-hydrothermal CO2 partially dissolved in groundwater or due to precipitation of CaCO3 and CO2 degassing related to silicate hydrolysis dissolving Ca2+.

Marrero, R.; Melian, G.; Padron, E.; Sortino, F.; Hernandez Perez, P. A.; Lopez, D. L.; Perez, N.

2009-12-01

406

Photosensitive dopants for liquid noble gases  

DOEpatents

In an ionization type detector for high energy radiation wherein the energy of incident radiation is absorbed through the ionization of a liquid noble gas and resulting free charge is collected to form a signal indicative of the energy of the incident radiation, an improvement comprising doping the liquid noble gas with photosensitive molecules to convert scintillation light due to recombination of ions, to additional free charge.

Anderson, David F. (Wheaton, IL)

1988-01-01

407

Fireball during combustion of hydrocarbon fueld releases II. Thermal radiation  

Microsoft Academic Search

The processes of radiative heat transfer in a fireball which develops upon ignition of a cloud of hydrocarbon fuel near the\\u000a Earth’s surface are simulated numerically. The emissive characteristics of combustion products (mixtures of nitrogen dioxide,\\u000a water vapor, and soot) are described using the weighted-sum-of-gray-gases model with temperature-dependent weighting coefficients.\\u000a The radiation field in the fireball for individual gray gases

G. M. Makhviladze; J. P. Roberts; S. E. Yakush

1999-01-01

408

Preserving noble gases in a convecting mantle.  

PubMed

High (3)He/(4)He ratios sampled at many ocean islands are usually attributed to an essentially undegassed lower-mantle reservoir with high (3)He concentrations. A large and mostly undegassed mantle reservoir is also required to balance the Earth's (40)Ar budget, because only half of the (40)Ar produced from the radioactive decay of (40)K is accounted for by the atmosphere and upper mantle. However, geophysical and geochemical observations suggest slab subduction into the lower mantle, implying that most or all of Earth's mantle should have been processed by partial melting beneath mid-ocean ridges and hotspot volcanoes. This should have left noble gases in both the upper and the lower mantle extensively outgassed, contrary to expectations from (3)He/(4)He ratios and the Earth's (40)Ar budget. Here we suggest a simple solution: recycling and mixing of noble-gas-depleted slabs dilutes the concentrations of noble gases in the mantle, thereby decreasing the rate of mantle degassing and leaving significant amounts of noble gases in the processed mantle. As a result, even when the mass flux across the 660-km seismic discontinuity is equivalent to approximately one lower-mantle mass over the Earth's history, high (3)He contents, high (3)He/(4)He ratios and (40)Ar concentrations high enough to satisfy the (40)Ar mass balance of the Earth can be preserved in the lower mantle. The differences in (3)He/(4)He ratios between mid-ocean-ridge basalts and ocean island basalts, as well as high concentrations of (3)He and (40)Ar in the mantle source of ocean island basalts, can be explained within the framework of different processing rates for the upper and the lower mantle. Hence, to preserve primitive noble gas signatures, we find no need for hidden reservoirs or convective isolation of the lower mantle for any length of time. PMID:19478782

Gonnermann, Helge M; Mukhopadhyay, Sujoy

2009-05-28

409

Solubility calculations for acid gases in amine blends  

SciTech Connect

Treating with alkanolamines is often used to sweeten gases containing only a few parts per million of CO/sub 2/ and H/sub 2/S. Primary amines such as monoethanolamine (MEA) have great affinity for acid gases and are able to produce high purity sweet gas; on the other hand, tertiary amines like methyldiethanolamine (MDEA) have large capacity and are easy to regenerate but, because they do not bind chemically with CO/sub 2/, they are unable to produce a sweetened gas low in this component. Recently, the use of amine blends has become a subject of potentially great commercial importance. Since, the range of possible amines and blend formulations is large, a method for predicting equilibrium solubility is needed. A rigorous thermodynamic model has been developed which uses the extended Debye-Huckel expression, is very similar to one developed for single-amine solutions, and involves the fitting of binary interaction parameters to experimental data. In this work the interaction parameters found to be important in the activity coefficient expression were fitted to each single-acid-gas single-amine subsystem using all published solubility data. The resulting model was then validated by comparing mixed-acid-gas single-amine solubility predictions with published VLE data. MEA-MDEA and DEA-MDEA blends have been studied in detail in this work. It is found that each amine contributes to the overall acid gas solubility in a nonlinear way and that the solubility curves can exhibit maxima and minima as a function of the relative concentrations of the amines.

Chakravarty, T.

1985-01-01

410

Catalytic Generation of Lift Gases for Balloons  

NASA Technical Reports Server (NTRS)

A lift-gas cracker (LGC) is an apparatus that generates a low-molecular-weight gas (mostly hydrogen with smaller amounts of carbon monoxide and/or carbon dioxide) at low gauge pressure by methanol reforming. LGCs are undergoing development for use as sources of buoyant gases for filling zero-gauge-pressure meteorological and scientific balloons in remote locations where heavy, high-pressure helium cylinders are not readily available. LGCs could also be used aboard large, zero-gauge-pressure, stratospheric research balloons to extend the duration of flight.

Zubrin, Robert; Berggren, Mark

2011-01-01

411

Apparatus Measures Permeation Of Gases Through Coupons  

NASA Technical Reports Server (NTRS)

Apparatus measures permeation of any variety of commercially available pure or mixed gases through polymeric or other material coupons of various thicknesses. Permeability measured at wide range of temperatures and pressures. Includes residual-gas-analyzer (RGA) sensor head and associated circuitry, and vacuum system. Also includes manifold with valves, through which gas of interest allowed to permeate through test coupon before traveling downstream to evacuated RGA sensor head. Temperature of test coupon monitored by thermocouple and maintained at specified value above ambient by use of electrical heating mantle or below ambient by use of bath of ethylene glycol, water, and dry ice.

Adam, Steven J.; Morrow, Jim T.; David, Carey E.

1995-01-01

412

Toxicity of pyrolysis gases from polytetrafluoroethylene  

NASA Technical Reports Server (NTRS)

A sample of polytetrafluoroethylene was evaluated for toxicity of pyrolysis gases, using various test conditions of the toxicity screening test method developed at the University of San Francisco. Time to death appears to be affected by the material of which the pyrolysis tube is made, with Monel tending to give longer times to death than quartz. When quartz tubes are used, time to death seems to be related to carbon monoxide concentration. When Monel tubes are used, carbon monoxide does not appear to be the principal toxicant.

Hilado, C. J.; Schneider, J. E.

1979-01-01

413

Mean free path in soccer and gases  

NASA Astrophysics Data System (ADS)

The trajectories of the molecules in an ideal gas and of the ball in a soccer game are compared. The great difference between these motions and some similarities are discussed. This example could be suitable for discussing many concepts in kinetic theory in a way that can be pictured by students for getting a more intuitive understanding. It could be suitable for an introductory course in vacuum techniques or undergraduate courses in kinetic theory of gases. Without going into the slightly harder quantitative results, the analysis presented might be used for introducing some ideas of kinetic theory qualitatively to high school students.

Luzuriaga, J.

2010-09-01

414

Why hybrid porous solids capture greenhouse gases?  

PubMed

Hybrid porous solids, with their tunable structures, their multifunctional properties and their numerous applications, are currently topical, particularly in the domain of adsorption and storage of greenhouse gases. Most of the data reported so far concern the performances of these solids in this domain, particularly in terms of adsorbed amounts of gas but do not explain at the atomic level why and how adsorption and storage occur. From a combination of structural, spectroscopic, thermodynamic experiments and of molecular simulations, this tutorial review proposes answers to these open questions with a special emphasis on CO(2) and CH(4) storage by some rigid and flexible hybrid porous materials. PMID:21180728

Férey, Gérard; Serre, Christian; Devic, Thomas; Maurin, Guillaume; Jobic, Hervé; Llewellyn, Philip L; De Weireld, Guy; Vimont, Alexandre; Daturi, Marco; Chang, Jong-San

2011-02-01

415

The Magnetic Susceptibilities of Several Organic Gases  

Microsoft Academic Search

A method for measuring the magnetic susceptibilities of gases similar in principle to that used by Wills and Hector but simpler in operation was developed. The following results given in molecular susceptibility ×106 were obtained: methane (CH4), -12.2; ethane (C2H6), -27.3; propane (C3H8), -40.5; butane (C4H10), -57.4; isobutane (C4H10), -56.3; ethylene (C2H4), -12.0; acetylene (C2H2)-12.5; using as standards H2, -3.94

Francis Bitter

1929-01-01

416

Method for detecting trace impurities in gases  

DOEpatents

A technique for considerably improving the sensitivity and specificity of infrared spectrometry as applied to quantitative determination of trace impurities in various carrier or solvent gases is presented. A gas to be examined for impurities is liquefied and infrared absorption spectra of the liquid are obtained. Spectral simplification and number densities of impurities in the optical path are substantially higher than are obtainable in similar gas-phase analyses. Carbon dioxide impurity (.about.2 ppm) present in commercial Xe and ppm levels of Freon 12 and vinyl chloride added to liquefied air are used to illustrate the method.

Freund, Samuel M. (Santa Fe, NM) [Santa Fe, NM; Maier, II, William B. (Los Alamos, NM); Holland, Redus F. (Los Alamos, NM) [Los Alamos, NM; Beattie, Willard H. (Los Alamos, NM) [Los Alamos, NM

1981-01-01

417

Strongly interacting Fermi gases with density imbalance.  

PubMed

We consider density-imbalanced Fermi gases of atoms in the strongly interacting, i.e., unitarity, regime. The Bogoliubov-de Gennes equations for a trapped superfluid are solved. They take into account the finite size of the system, as well as give rise to both phase separation and Fulde-Ferrel-Larkin-Ovchinnikov-type oscillations in the order parameter. We show how radio-frequency spectroscopy reflects the phase separation, and can provide direct evidence of the FFLO-type oscillations via observing the nodes of the order parameter. PMID:16605801

Kinnunen, J; Jensen, L M; Törmä, P

2006-03-24

418

Toxicity of pyrolysis gases from wood  

NASA Technical Reports Server (NTRS)

The toxicity of the pyrolysis gases from nine wood samples was investigated. The samples of hardwoods were aspen poplar, beech, yellow birch, and red oak. The samples of softwoods were western red cedar, Douglas fir, western hemlock, eastern white pine, and southern yellow pine. There was no significant difference between the wood samples under rising temperature conditions, which are intended to simulate a developing fire, or under fixed temperature conditions, which are intended to simulate a fully developed fire. This test method is used to determine whether a material is significantly more toxic than wood under the preflashover conditions of a developing fire.

Hilado, C. J.; Huttlinger, N. V.; Oneill, B. A.; Kourtides, D. A.; Parker, J. A.

1977-01-01

419

Photoacoustic detection of gases using microcantilevers  

NASA Astrophysics Data System (ADS)

We describe a new technique for measuring the infrared absorption spectra of gases using atomic force microscope microcantilevers. This photoacoustic system is demonstrated for a dilute acetylene/helium mixture by recording the acetylene ?1+?3 infrared overtone transitions using a wavelength modulated tunable diode laser as the infrared light source. The technique presents significant advantages over existing methods in terms of size, simplicity, speed and insensitivity to ambient vibrations. The maximum achievable signal-to-noise for resonant and non-resonant photoacoustic excitation of the microcantilever is examined and is found to be limited by the microcantilever's Brownian noise.

Adamson, Brian D.; Sader, John E.; Bieske, Evan J.

2009-12-01

420

Role of Radiation in Polymer Chemistry.  

National Technical Information Service (NTIS)

The very important role which polymer chemistry plays in radiation technology is discussed. The present status of radiation processing and the radiation sources that are used by industry are described. The process by which ionising radiation interacts wit...

T. A. Du Plessis

1977-01-01

421

The measurement of tropospheric trace gases at Fritz Peak Observatory, Colorado, by long-path absorption: OH and ancillary gases  

SciTech Connect

The determination of the concentration of the hydroxyl radical in the troposphere is of fundamental importance to an understanding of the chemistry of the lower atmosphere. Described here are experiments located at Fritz Peak Observatory, Colorado, that measure of OH concentration to a sensitivity limit of about 5 X 10{sup 5} cm{sup {minus}3} (0.025 pptv) with absolute error approximately {+-}30% and, simultaneously, measure the concentrations of H{sub 2}O, SO{sub 2}, CH{sub 2}O, NO{sub 2}, NO{sub 3}, HONO, O{sub 3}, and other trace gases in the troposphere that affect OH concentration to provide a test of photochemical theories of OH formation and destruction. An informal OH intercomparison campaign that occurred at Fritz Peak in 1991 and the 1993 Tropospheric OH Photochemistry Experiment are discussed. 33 refs., 14 figs., 2 tabs.

Mount, G.H.; Harder, J.W. [National Oceanic and Atmospheric Administration, Boulder, CO (United States)] [National Oceanic and Atmospheric Administration, Boulder, CO (United States)

1995-10-01

422

Solid-state detector system for measuring concentrations of tritiated water vapour and other radioactive gases  

NASA Astrophysics Data System (ADS)

A detector system was built using a silicon photodiode plus preamplifier and a cesium iodide scintillator plus preamplifier that were commercially available. The potential of the system for measuring concentrations of tritiated water vapour in the presence of other radioactive sources was investigated. For purposes of radiation protection, the sensitivity of the detector system was considered too low for measuring tritiated water vapour concentrations in workplaces such as nuclear power plants. Nevertheless, the spectrometry capability of the system was used successfully to differentiate amongst some radioactive gases in laboratory tests. Although this relatively small system can measure radioactive noble gases as well as tritiated water vapour concentrations, its response to photons remains an issue.

Nunes, J. C.; Surette, R. A.; Wood, M. J.

1999-08-01

423

Radiative forcing caused by rocket engine emissions  

NASA Astrophysics Data System (ADS)

Space transportation plays an important and growing role in Earth's economic system. Rockets uniquely emit gases and particles directly into the middle and upper atmosphere where exhaust from hundreds of launches accumulates, changing atmospheric radiation patterns. The instantaneous radiative forcing (RF) caused by major rocket engine emissions CO2, H2O, black carbon (BC), and Al2O3 (alumina) is estimated. Rocket CO2 and H2O emissions do not produce significant RF. BC and alumina emissions, under some scenarios, have the potential to produce significant RF. Absorption of solar flux by BC is likely the main RF source from rocket launches. In a new finding, alumina particles, previously thought to cool the Earth by scattering solar flux back to space, absorb outgoing terrestrial longwave radiation, resulting in net positive RF. With the caveat that BC and alumina microphysics are poorly constrained, we find that the present-day RF from rocket launches equals 16 ± 8 mW m-2. The relative contributions from BC, alumina, and H2O are 70%, 28%, and 2%. respectively. The pace of rocket launches is predicted to grow and space transport RF could become comparable to global aviation RF in coming decades. Improved understanding of rocket emission RF requires more sophisticated modeling and improved data describing particle microphysics.

Ross, Martin N.; Sheaffer, Patti M.

2014-04-01

424

Process for removing hydrogen sulfide from gases particularly coal pyrolysis gases  

Microsoft Academic Search

Hydrogen sulfide is first removed by ammoniacal liquor from coke oven gas in the bottom part of a gas scrubber. In the top part of the scrubber, two consecutively-arranged fine scrubbing stages remove hydrogen sulfide by treating the gases, in the upper stage, with a caustic soda solution or a caustic potash solution. Beneath the upper scrubbing stage is the

H. Ritter; E. T. Herpers

1985-01-01

425

Noble gases in E-chondrites  

NASA Astrophysics Data System (ADS)

The combination of noble gas data for 12 E-chondrites with literature data shows K-Ar ages greater than 4 AE for 14 out of 18 meteorites, while U, Th-He ages are often shorter. Cosmic ray exposure ages are found to differ systematically between types E4 and E6, with the respective, below-16 Myr and above-30 Myr values implying that the E-chondrite parent body predominantly contains a single petrologic type on the 1 km scale of individual impacts in contrast to the mixed parent bodies of the ordinary chondrites. Amounts of planetary gas in E4-E6 chondrites fall in the range for ordinary chondrites of types 4-6, but fail to correlate with petrologic type or volatile trace element contents, in contrast to the ordinary chondrites. Analyses of mineral separates show that the planetary gases are concentrated in an HFand HCl-insoluble mineral, similar to phase Q. The subsolar gases are located in an HCl- and HNO3-resistant phase.

Crabb, J.; Anders, E.

1981-12-01

426

Gases Inside the Earth / Muddy Waters  

NSDL National Science Digital Library

This two-part radio broadcast first focuses on how scientists are re-evaluating their theories on how the Earth was formed, then on exploration for new life forms found in the sediments of ocean floors. By looking at volcanic hotspots, geologists can sample gases from deep inside the mantle of the Earth. These dissolved gases include particles from the solar wind and impacting asteroids. This broadcast discusses a new theory suggesting there were two distinct phases in the development of Earth and explains how Earth may have been hit by something as big as Mars, causing the formation of the Moon. There is discussion about how the two layers of the Earth mantle interact. In the second half of the broadcast, it is estimated there could be as many species below ground in deep-sea sediments as there are above water in our rainforests. There is discussion of the search for a family of bacteria called actinomycetes, which could be used to treat methicillin resistant Staphylococcus aureus (MRSA, an organism resistant to commonly used antibiotics); the range of species on the seafloor; and oil and gas companies' surveys to check what effect their activities are having on the ocean bottom. The broadcast is 29 minutes in length.

427

Hydrodynamics and universality in cold atomic gases  

NASA Astrophysics Data System (ADS)

Recent flurry of experiments on out-of-equilibrium dynamics in cold gases (Bosonic and Fermionic) has raised great interest in understanding collective behaviour of interacting particles. Although the dynamics of interacting gases depends on many details of the system, a great insight can be obtained in a rather universal limit of weak non-linearity, dispersion and dissipation. In this limit, using a reductive perturbation method we map many hydrodynamic models relevant to cold atoms to well known chiral one-dimensional equations such as Korteweg-de Vries (KdV), Burgers, KdV-Burgers, and Benjamin-Ono equations. This mapping [1] of rather complicated hydrodynamic equations to known chiral one-dimensional equations is of great experimental and theoretical interest. For instance, this mapping gives a simple way to make estimates for original hydrodynamic equations and to study phenomena such as shock waves, solitons and the interplay between nonlinearity, dissipation and dispersion. All these phenomena have been observed in experiments and are the hallmarks of nonlinear hydrodynamics.[4pt] [1] M. Kulkarni, A. G. Abanov, Phys. Rev. A 86, 033614 (2012)

Abanov, Alexander; Kulkarni, Manas

2013-03-01

428

Emissions of sulfur gases from wetlands  

NASA Technical Reports Server (NTRS)

Data on the emissions of sulfur gases from marine and freshwater wetlands are summarized with respect to wetland vegetation type and possible formation mechanisms. The current data base is largest for salt marshes inhabited by Spartina alterniflora. Both dimethyl sulfide (DMS) and hydrogen sulfide (H2S) dominate emissions from salt marshes, with lesser quantities of methyl mercaptan (MeSH), carbonyl sulfide (COS), carbon disulfide (CS2) and dimethyl disulfide (DMDS) being emitted. High emission rates of DMS are associated with vegetation that produces the DMS precursor dimethylsulfonionpropionate (DMSP). Although large quantities of H2S are produced in marshes, only a small percentage escapes to the atmosphere. High latitude marshes emit less sulfur gases than temperate ones, but DMS still dominates. Mangrove-inhabited wetlands also emit less sulfur than temperate S. alterniflora marshes. Few data are available on sulfur gas emissions from freshwater wetlands. In most instances, sulfur emissions from temperate freshwater sites are low. However, some temperate and subtropical freshwater sites are similar in magnitude to those from marine wetlands which do not contain vegetation that produces DMSP. Emissions are low in Alaskan tundra but may be considerably higher in some bogs and fens.

Hines, Mark E.

1992-01-01

429

Mantle-derived noble gases in natural gases from Songliao Basin, China  

SciTech Connect

Abundances and isotopic compositions of noble gases have been measured in six natural gas samples (CO{sub 2} and CH{sub 4}-rich) from the Songliao Basin, Jilin Province, in northeastern China. The samples contain noble gases of mantle origin. The {sup 3}He/{sup 4}He ratio reaches 5.0 times the atmospheric ratio. In a three-isotope plot of neon, the {sup 20}Ne/{sup 22}Ne (up to 10.9) and {sup 21}Ne/{sup 22}Ne (up to 0.051) ratios make a positive correlation array together with natural gases from other continental areas. Compared with a correlation band for MORB, the natural gases from other continental areas. Compared with a correlation band for MORB, the natural gases have a lower slope with more nucleogenic {sup 21}Ne. The natural gas samples contain radiogenic argon with {sup 40}Ar/{sup 36}Ar ratios up to 7700. A positive correlation between {sup 40}Ar/{sup 36}Ar and nuclear reaction like {sup 35}Cl ({alpha}, p) {sup 38}Ar. Apparent excesses of {sup 129}Xe, {sup 132-136}Xe are recognized in four samples. The excess of {sup 129}Xe (up to 3%) can be attributed to a decay of extinct {sup 129}I. Excess {sup 132-136}Xe is not large enough to determine if the origin of the excess is {sup 238}U or {sup 244}Pu. Anomaly in {sup 129}Xe/{sup 130}Xe ratio is correlated with that of {sup 136}Xe/{sup 130}Xe. The isotopic features of the natural gases with radiogenic {sup 4}He and nucleogenic {sup 21}Ne can be produced within the crust. However, a natural gas from another basin in eastern China with a different reservoir age contains mantle derived neon which falls on the neon correlation line formed by the samples from the Songliao Basin. This consistency suggests that the isotopic features of the natural gases aren`t necessarily ascribable to surface contamination of radiogenic and nucleogenic isotopes. 58 refs., 6 figs., 1 tab.

Xu, Sheng; Nakai, Shun`ichi; Wakita, Hiroshi [Univ. of Tokyo, Bunkyo-ku (Japan)] [and others] [Univ. of Tokyo, Bunkyo-ku (Japan); and others

1995-12-31

430

Carbon Dioxide Information Analysis Center and World Data Center for Atmospheric Trace Gases, Fiscal Year 2002 Annual Report  

SciTech Connect

The Carbon Dioxide Information Analysis Center (CDIAC), which includes the World Data Center (WDC) for Atmospheric Trace Gases, is the primary global change data and information analysis center of the U.S. Department of Energy (DOE). More than just an archive of data sets and publications, CDIAC has, since its inception in 1982, enhanced the value of its holdings through intensive quality assurance, documentation, and integration. Whereas many traditional data centers are discipline-based (for example, meteorology or oceanography), CDIAC's scope includes potentially anything and everything that would be of value to users concerned with the greenhouse effect and global climate change, including atmospheric concentrations and atmospheric emissions of carbon dioxide (CO{sub 2}) and other radiatively active gases; the role of the terrestrial biosphere and the oceans in the biogeochemical cycles of greenhouse gases; long-term climate trends; the effects of elevated CO{sub 2} on vegetation; and the vulnerability of coastal areas to rising sea levels.

Cushman, R.M.

2003-08-28

431

Radiation Symbols  

MedlinePLUS

... Effects Ionizing & Non-Ionizing Radiation Understanding Radiation: Radiation Symbols Radiation Protection Basics Main Page History of Radiation ... Michigan's Radiation and Health Physics Page . United Nations Symbol In February of 2007, the United Nations introduced ...

432

On segregation of noble gases in water-based Single Bubble Sonoluminescence  

NASA Astrophysics Data System (ADS)

A long-standing issue in the field of long time stable water based single bubble sonoluminescence has been the close similarity of the spectra to that of blackbody radiation. Looking for the effects of possible segregation of noble gases has been suggested as a means to investigate whether the similarity is just a weird coincidence with the bubbles being on the whole transparent to their own radiation. We have investigated spectra from bubbles seeded with various mixtures of helium and neon with xenon and argon using a novel transformation that allows for a single parameter characterization of the spectra, with the surprising result that although no trace of segregation is found, the radiation seems to be highly thermalized in all cases.

Levinsen, Mogens

2011-03-01

433

Patterns of Trace Gases Near Sources of Global Pollution  

Microsoft Academic Search

Many trace gases are increasing in the earth's armosphere and may couase global environmental changes in the future. Consequently there has been growing interest in the cycles of the long-lived gases that are likely to contribute the most to global change. At present there are four such gases: methane (CHâ), nitrous oxide (Nââ, trichlorofluoromethane (CClâF,F-11), and dichlorodifluoromethane (CClâFâ,F-12). Methane and

M. A. K. Khalil; R. A. Rasmussen

1990-01-01

434

Dynamics of plasma gratings in atomic and molecular gases.  

PubMed

The decay of the plasma grating formed at the intersection of two femtosecond filaments is measured in several molecular and atomic gases. The grating evolution is ruled by ambipolar diffusion in atomic gases and by a combination of ambipolar diffusion and collision-assisted free electron recombination in molecular gases. Electron diffusion and recombination coefficients are extracted for Ne, Ar, Kr, Xe, N2, O2, CO2, and air at 1 bar. PMID:23031032

Durand, M; Jarnac, A; Liu, Y; Prade, B; Houard, A; Tikhonchuk, V; Mysyrowicz, A

2012-09-01

435

Method for controlling corrosion in thermal vapor injection gases  

DOEpatents

An improvement in the method for producing high pressure thermal vapor streams from combustion gases for injection into subterranean oil producing formations to stimulate the production of viscous minerals is described. The improvement involves controlling corrosion in such thermal vapor gases by injecting water near the flame in the combustion zone and injecting ammonia into a vapor producing vessel to contact the combustion gases exiting the combustion chamber.

Sperry, John S. (Houston, TX); Krajicek, Richard W. (Houston, TX)

1981-01-01

436

Snowpack Chemistry of Reactive Gases at Station Concordia, Antarctica  

NASA Astrophysics Data System (ADS)

During December 2012 a new experiment for the study of snow photochemical processes and surface gas exchange was installed at Dome Concordia, Antarctica. The experiment consists of two sampling manifolds ('snow tower') which facilitate the withdrawal of interstitial firn air from four depths in the snowpack and from above the surface. One of these snow towers can be shaded for investigation of the dependency of snow chemistry on solar radiation. A nearby 12 m meteorological tower facilitates above surface turbulence and trace gas gradient measurements. Temperature profiles and UV and IR light penetration are monitored in the snowpack. Air samples are directed through sampling lines to a nearby underground laboratory that houses the experiment control system and gas monitors. The system is fully automated, sampling gases from the array of inlet ports sequentially, and is intended to be operated continuously for a full annual cycle. The computerized control system can be accessed remotely for data retrieval and quality control and for configuring experimental details. Continuous gas measurements include ozone, nitrogen oxides, methane, carbon monoxide, and gaseous elemental mercury. Whole air samples were sampled on four occasions for volatile organic compound analysis. The objective of this research is the study of the year-round snowpack gas chemistry and its dependency on snowpack and above surface physical and environmental conditions. A particular emphasis will be the investigation of the effects of increased UV radiation during the occurrence of the stratospheric ozone hole. We will present the conceptual design of the experiment and data examples from the first three months of the experiment.

Helmig, Detlev; Mass, Alex; Hueber, Jacques; Fain, Xavier; Dommergue, Aurelien; Barbero, Albane; Savarino, Joel

2013-04-01

437

Hydrogen Peroxide Enhances Removal of NOx from Flue Gases  

NASA Technical Reports Server (NTRS)

Pilot scale experiments have demonstrated a method of reducing the amounts of oxides of nitrogen (NOx) emitted by industrial boilers and powerplant combustors that involves (1) injection of H2O2 into flue gases and (2) treatment of the flue gases by caustic wet scrubbing like that commonly used to remove SO2 from combustion flue gases. Heretofore, the method most commonly used for removing NOx from flue gases has been selective catalytic reduction (SCR), in which the costs of both installation and operation are very high. After further development, the present method may prove to be an economically attractive alternative to SCR.

Collins, Michelle M.

2005-01-01

438

Quantum control and measurement of spins in laser cooled gases  

NASA Astrophysics Data System (ADS)

Quantum information processing (QIP) requires three important ingredients: (i) preparing a desired initial quantum state, usually highly pure; (ii) controlling the dynamical evolution, usually via a desired unitary transformation; (iii) measuring the desired information encoded in the final quantum state. Many physical platforms are being developed for QIP, including trapped ions, semiconductor quantum dots, and atoms in optical lattices. In these cases, it is the spins of the system that encode the quantum information. Spins are natural carriers of quantum information given their long coherence times and our ability to control them with a variety of external electromagnetic fields. In addition, spins in laser-cooled atomic gases are an excellent testbed for exploring QIP protocols because of our ability to initially prepare highly pure states and employ the well-developed tools of quantum optics and coherent spectroscopy. In this talk I will give an overview of recent theory and experiment in the control and measurement of spins in laser-cooled atomic gases. We consider the hyperfine magnetic sublevels in the ground electronic states of ^133Cs, a 16-dimensional Hilbert space. We can explore all three ingredients described above: preparation of an arbitrary superposition state, evolution through an arbitrary unitary matrix, and readout through quantum state reconstruction of the full density matrix. We employ the tools of optimal quantum control and quantum estimation theory. The implementation involves atoms controlled by radio-frequency, microwave, a optical fields, and measured via polarization spectroscopy. The experiment is performed in the group of Prof. Poul S. Jessen, University of Arizona. This work was supported by the National Science Foundation.

Deutsch, Ivan

2012-10-01

439

Solar radiation modelling  

Microsoft Academic Search

The Sun is the main energy source of the life on the Earth. Thus, solar radiation energy data and models are important for many areas of research and applications. Many parameters influence the amount of solar energy at a particular standing point of the Earth's surface; therefore, many solar radiation models were produced in the last few years. Solar radiation

Klemen Zaksek; Tomaz Podobnikar; Krištof Oštir

2005-01-01

440

Mantle-derived noble gases in natural gases from Songliao Basin, China  

NASA Astrophysics Data System (ADS)

Abundances and isotopic compositions of noble gases have been measured in six natural gas samples (CO 2 and CH 4-rich) from the Songliao Basin, Jilin Province, in northeastern China. The samples contain noble gases of mantle origin. The 3He/4He ratio reaches 5.0 times the atmospheric ratio. In a three-isotope plot of neon, the 20Ne/22Ne (up to 10.9) and 21Ne/22Ne (up to 0.051) ratios make a positive correlation array together with natural gases from other continental areas. Compared with a correlation band for MORB, the natural gases have a lower slope with more nucleogenic 21Ne. The natural gas samples contain radiogenic argon with 40Ar/36Ar ratios up to 7700. A positive correlation between 40Ar/36Ar and 20Ne/22Ne ratios indicates occurrence of mantle-derived Ar. Slight excess of 38Ar can be attributed to a nuclear reaction like 35C1 (?, p) 38 Ar. Apparent excesses of 1292'Xe, 132-136Xe are recognized in four samples. The excess of 129Xe (up to 3%) can be attributed to a decay of extinct 129I. Excess 132-136Xe is not large enough to determine if the origin of the excess is 238U or 244Pu. Anomaly in 129Xe/130Xe ratio is correlated with that of 136Xe/130Xe. The isotopic features of the natural gases with radiogenic 4He and nucleogenic 21Ne can be produced within the crust. Alternatively, they may reflect the geochemical features of the subcontinental mantle which has been enriched in U, Th. We can not distinguish the two possibilities. However, a natural gas from another basin in eastern China with a different reservoir age contains mantle derived neon which falls on the neon correlation line formed by the samples from the Songliao Basin. This consistency suggests that the isotopic features of the natural gases aren't necessarily ascribable to surface contamination of radiogenic and nucleogenic isotopes.

Xu, Sheng; Nakai, Shun'ichi; Wakita, Hiroshi; Wang, Xianbin

1995-11-01

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