WorldWideScience

Sample records for term atmospheric diffusion

  1. Verification of atmospheric diffusion models using data of long term atmospheric diffusion experiments

    International Nuclear Information System (INIS)

    Tamura, Junji; Kido, Hiroko; Hato, Shinji; Homma, Toshimitsu

    2009-03-01

    Straight-line or segmented plume models as atmospheric diffusion models are commonly used in probabilistic accident consequence assessment (PCA) codes due to cost and time savings. The PCA code, OSCAAR developed by Japan Atomic Energy Research Institute (Present; Japan Atomic Energy Agency) uses the variable puff trajectory model to calculate atmospheric transport and dispersion of released radionuclides. In order to investigate uncertainties involved with the structure of the atmospheric dispersion/deposition model in OSCAAR, we have introduced the more sophisticated computer codes that included regional meteorological models RAMS and atmospheric transport model HYPACT, which were developed by Colorado State University, and comparative analyses between OSCAAR and RAMS/HYPACT have been performed. In this study, model verification of OSCAAR and RAMS/HYPACT was conducted using data of long term atmospheric diffusion experiments, which were carried out in Tokai-mura, Ibaraki-ken. The predictions by models and the results of the atmospheric diffusion experiments indicated relatively good agreements. And it was shown that model performance of OSCAAR was the same degree as it of RAMS/HYPACT. (author)

  2. Data of long term atmospheric diffusion experiments (Winter, 1992)

    Energy Technology Data Exchange (ETDEWEB)

    Hayashi, Takashi; Chino, Masamichi; Yamazawa, Hiromi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment] [and others

    1998-10-01

    The data were obtained in the long-term atmospheric diffusion experiments in the Tokai area, autumn, 1991 which were a part of the Evaluation Safety Demonstration Experiments of Environmental Radiation entrusted with the Science and Technology Agency. The experiments were conducted by JAERI in cooperation with the Japan Weather Association. The report includes tracer concentration data of surface sampling points and meteorological data. (author)

  3. Atmospheric turbulence and diffusion research

    International Nuclear Information System (INIS)

    Hosker, R.P. Jr.

    1993-01-01

    The Atmospheric Turbulence and Diffusion Division (well known in the atmospheric dispersion community as the Atmospheric Turbulence and Diffusion Laboratory, ATDL) is one of several field facilities of NOAAs Air Resources Laboratory, headquartered in Silver Spring, Maryland. The laboratory conducts research on matters of atmospheric diffusion and turbulent exchange, concerning air quality. ATDD focuses attention on the physics of the lower atmosphere, with special emphasis on the processes contributing to atmospheric transport, dispersion, deposition, and air-surface exchange, and on the development of predictive capabilities using the results of this research. Research is directed toward issues of national and global importance related to the missions of DOE, to DOE's Oak Ridge Field Office, and to NOAA. The program is divided into four major projects: plume transport and diffusion in the planetary boundary layer, complex topography, canopy micrometeorology, and air-surface exchange

  4. Atmospheric diffusion of large clouds

    Energy Technology Data Exchange (ETDEWEB)

    Crawford, T. V. [Univ. of California, Lawrence Radiation Lab., Livermore, California (United States)

    1967-07-01

    Clouds of pollutants travel within a coordinate system that is fixed to the earth's surface, and they diffuse and grow within a coordinate system fixed to the cloud's center. This paper discusses an approach to predicting the cloud's properties, within the latter coordinate system, on space scales of a few hundred meters to a few hundred kilometers and for time periods of a few days. A numerical cloud diffusion model is presented which starts with a cloud placed arbitrarily within the troposphere. Similarity theories of atmospheric turbulence are used to predict the horizontal diffusivity as a function of initial cloud size, turbulent atmospheric dissipation, and time. Vertical diffusivity is input as a function of time and height. Therefore, diurnal variations of turbulent diffusion in the boundary layer and effects of temperature inversions, etc. can be modeled. Nondiffusive cloud depletion mechanisms, such as dry deposition, washout, and radioactive decay, are also a part of this numerical model. An effluent cloud, produced by a reactor run at the Nuclear Rocket Development Station, Nevada, is discussed in this paper. Measurements on this cloud, for a period of two days, are compared to calculations with the above numerical cloud diffusion model. In general, there is agreement. within a factor of two, for airborne concentrations, cloud horizontal area, surface air concentrations, and dry deposition as airborne concentration decreased by seven orders of magnitude during the two-day period. (author)

  5. Evaluation of empirical atmospheric diffusion data

    International Nuclear Information System (INIS)

    Horst, T.W.; Doran, J.C.; Nickola, P.W.

    1979-10-01

    A study has been made of atmospheric diffusion over level, homogeneous terrain of contaminants released from non-buoyant point sources up to 100 m in height. Current theories of diffusion are compared to empirical diffusion data, and specific dispersion estimation techniques are recommended which can be implemented with the on-site meteorological instrumentation required by the Nuclear Regulatory Commission. A comparison of both the recommended diffusion model and the NRC diffusion model with the empirical data demonstrates that the predictions of the recommended model have both smaller scatter and less bias, particularly for groundlevel sources

  6. Evaluation of empirical atmospheric diffusion data

    Energy Technology Data Exchange (ETDEWEB)

    Horst, T.W.; Doran, J.C.; Nickola, P.W.

    1979-10-01

    A study has been made of atmospheric diffusion over level, homogeneous terrain of contaminants released from non-buoyant point sources up to 100 m in height. Current theories of diffusion are compared to empirical diffusion data, and specific dispersion estimation techniques are recommended which can be implemented with the on-site meteorological instrumentation required by the Nuclear Regulatory Commission. A comparison of both the recommended diffusion model and the NRC diffusion model with the empirical data demonstrates that the predictions of the recommended model have both smaller scatter and less bias, particularly for ground-level sources.

  7. Atmospheric horizontal divergence and diffusion

    International Nuclear Information System (INIS)

    Castans, M.

    1981-01-01

    The action of horizontal divergence on diffusion near the ground is established through.a very simple flow model. The shape of the well-known Pasquill-Gifford-Turner curves, that apparently take account in some way of divergence, is justified. The possibility of explaining the discre--pancies between the conventional straight line model and experimental results, mainly under low-wind-speed satable conditions, is considered. Some hints for further research are made. (auth.)

  8. Diffusive retention of atmospheric gases in chert

    Science.gov (United States)

    Pettitt, E.; Cherniak, D. J.; Watson, E. B.; Schaller, M. F.

    2016-12-01

    Throughout Earth's history, the volatile contents (N2, CO2, Ar) of both deep and shallow terrestrial reservoirs has been dynamic. Volatiles are important chemical constituents because they play a significant role in regulating Earth's climate, mediating the evolution of complex life, and controlling the properties of minerals and rocks. Estimating levels of atmospheric volatiles in the deep geological past requires interrogation of materials that have acquired and retained a chemical memory from that time. Cherts have the potential to trap atmospheric components during formation and later release those gases for analysis in the laboratory. However, cherts have been underexploited in this regard, partly because their ability to retain a record of volatile components has not been adequately evaluated. Before cherts can be reliably used as indicators of past levels of major atmospheric gases, it is crucial that we understand the diffusive retentiveness of these cryptocrystalline silica phases. As the first step toward quantifying the diffusivity and solubility of carbon dioxide and nitrogen in chert, we have performed 1-atmosphere diffusive-uptake experiments at temperatures up to 450°C. Depth profiles of in-diffusing gases are measured by nuclear reaction analysis (NRA) to help us understand the molecular-scale transport of volatiles and thus the validity of using chert-bound volatiles to record information about Earth history. Data collected to date suggest that at least some cherts are ideal storage containers and can retain volatiles for a geologically long time. In addition to these diffusion experiments, preliminary online-crush fast-scan measurements using a quadrupole mass spectrometer indicate that atmospheric volatiles are released upon crushing various chert samples. By coupling such volatile-release measurements made by mass spectrometry with diffusion experiments, we are uniquely able to address the storage and fidelity of volatiles bound in crustal

  9. Data of atmospheric diffusion experiments (Tsukuba, 1989)

    International Nuclear Information System (INIS)

    Hayashi, Takashi; Chino, Masamichi; Yamazawa, Hiromi; Moriuchi, Shigeru; Ishikawa, Hirohiko; Adachi, Takashi; Kojima, Hiromi

    1999-08-01

    The data were obtained in the atmospheric diffusion experiments in the Tsukuba area, 1989 which were a part of the Experiment to Demonstrate the Propriety of Atmospheric Dispersion Evaluation Method for Safety Analysis, entrusted with the Science and Technology Agency. The experiments were conducted by JAERI in cooperation with the Japan Weather Association. The report contains tracer concentration data of surface sampling points and meteorological data. (author)

  10. Solution of time dependent atmospheric diffusion equation with a proposed diffusion coefficient

    International Nuclear Information System (INIS)

    Mayhoub, A.B.; Essa, KH.S.M.; Aly, SH.

    2004-01-01

    One-dimensional model for the dispersion of passive atmospheric contaminant (not included chemical reactions) in the atmospheric boundary layer is considered. On the basis of the gradient transfer theory (K-theory), the time dependent diffusion equation represents the dispersion of the pollutants is solved analytically. The solution depends on diffusion coefficient K', which is expressed in terms of the friction velocity 'u the vertical coordinate -L and the depth of the mixing layer 'h'. The solution is obtained to either the vertical coordinate 'z' is less or greater than the mixing height 'h'. The obtained solution may be applied to study the atmospheric dispersion of pollutants

  11. Atmospheric diffusion wind tunnel with automatic measurement

    Energy Technology Data Exchange (ETDEWEB)

    Maki, S; Sakai, J; Murata, E

    1974-01-01

    A wind tunnel which permits estimates of atmospheric diffusion is described. Smoke from power plant smoke stacks, for example, can be simulated and traced to determine the manner of diffusion in the air as well as the grade of dilution. The wind tunnel is also capable of temperature controlled diffusion tests in which temperature distribution inside the wind tunnel is controlled. A minimum wind velocity of 10 cm can be obtained with accuracy within plus or minus 0.05 percent using a controlled direct current motor; diffusion tests are often made at low wind velocity. Fully automatic measurements can be obtained by using a minicomputer so that the operation and reading of the measuring instruments can be remotely controlled from the measuring chamber. (Air Pollut. Abstr.)

  12. Atmospheric transport, diffusion, and deposition of radioactivity

    International Nuclear Information System (INIS)

    Crawford, T.V.

    1969-01-01

    From a meteorological standpoint there are two types of initial sources for atmospheric diffusion from Plowshare applications. One is the continuous point-source plume - a slow, small leak from an underground engineering application. The other is the large cloud produced almost instantaneously from a cratering application. For the purposes of this paper the effluent from neither type has significant fall speed. Both are carried by the prevailing wind, but the statistics of diffusion for each type are different. The use of constant altitude, isobaric and isentropic techniques for predicting the mean path of the effluent is briefly discussed. Limited data are used to assess the accuracy of current trajectory forecast techniques. Diffusion of continuous point-source plumes has been widely studied; only a brief review is given of the technique used and the variability of their results with wind speed and atmospheric stability. A numerical model is presented for computing the diffusion of the 'instantaneously-produced' large clouds. This model accounts for vertical and diurnal changes in atmospheric turbulence, wet and dry deposition, and radioactivity decay. Airborne concentrations, cloud size, and deposition on the ground are calculated. Pre- and post-shot calculations of cloud center, ground level concentration of gross radioactivity, and dry and wet deposition of iodine-131 are compared with measurements on Cabriolet and Buggy. (author)

  13. Atmospheric transport, diffusion, and deposition of radioactivity

    Energy Technology Data Exchange (ETDEWEB)

    Crawford, T V [Lawrence Radiation Laboratory, Livermore, CA (United States)

    1969-07-01

    From a meteorological standpoint there are two types of initial sources for atmospheric diffusion from Plowshare applications. One is the continuous point-source plume - a slow, small leak from an underground engineering application. The other is the large cloud produced almost instantaneously from a cratering application. For the purposes of this paper the effluent from neither type has significant fall speed. Both are carried by the prevailing wind, but the statistics of diffusion for each type are different. The use of constant altitude, isobaric and isentropic techniques for predicting the mean path of the effluent is briefly discussed. Limited data are used to assess the accuracy of current trajectory forecast techniques. Diffusion of continuous point-source plumes has been widely studied; only a brief review is given of the technique used and the variability of their results with wind speed and atmospheric stability. A numerical model is presented for computing the diffusion of the 'instantaneously-produced' large clouds. This model accounts for vertical and diurnal changes in atmospheric turbulence, wet and dry deposition, and radioactivity decay. Airborne concentrations, cloud size, and deposition on the ground are calculated. Pre- and post-shot calculations of cloud center, ground level concentration of gross radioactivity, and dry and wet deposition of iodine-131 are compared with measurements on Cabriolet and Buggy. (author)

  14. Results of atmospheric diffusion experiments, vol.3

    International Nuclear Information System (INIS)

    Kakuta, Michio; Hayashi, Takashi; Adachi, Takashi.

    1988-02-01

    An extensive study on 'Emergency monitoring and prediction code system' has been carried in JAERI since 1980. Six series of field experiments on atmospheric diffusion were conducted to develop and verify the prediction models for environmental concentration distribution following accidental release of radioactivity. Results of field experiments (Inland complex terrain, surface and elevated point sources) conducted in 15 - 19th October 1984 (TSUKUBA84) and in 6 - 10th November 1985 (TSUKUBA85) are contained in this volume. (author)

  15. Solution of the atmospheric diffusion equation with a realistic diffusion coefficient and time dependent mixing height

    International Nuclear Information System (INIS)

    Mayhoub, A.B.; Etman, S.M.

    1997-01-01

    One dimensional model for the dispersion of a passive atmospheric contaminant (neglecting chemical reactions) in the atmospheric boundary layer is introduced. The differential equation representing the dispersion of pollutants is solved on the basis of gradient-transfer theory (K- theory). The present approach deals with a more appropriate and realistic profile for the diffusion coefficient K, which is expressed in terms of the friction velocity U, the vertical coordinate z and the depth of the mixing layer h, which is taken time dependent. After some mathematical simplification, the equation analytic obtained solution can be easily applied to case study concerning atmospheric dispersion of pollutants

  16. Verification of atmospheric diffusion models with data of atmospheric diffusion experiments

    International Nuclear Information System (INIS)

    Hato, Shinji; Homma, Toshimitsu

    2009-02-01

    The atmospheric diffusion experiments were implemented by Japan Atomic Energy Research Institute (JAERI) around Mount Tsukuba in 1989 and 1990, and the tracer gas concentration were monitored. In this study, the Gauss Plume Model and RAMS/HYPACT that are meteorological forecast code and atmospheric diffusion code with detailed physical law are made a comparison between monitored concentration. In conclusion, the Gauss Plume Model is better than RAM/HYPACT even complex topography if the estimation is around tens of kilometer form release point and the change in weather is constant for short time. This reason is difference of wind between RAMS and observation. (author)

  17. Atmospheric diffusion study and its application to nuclear energy

    International Nuclear Information System (INIS)

    Chino, Masamichi

    1990-01-01

    The report reviews studies on atmospheric diffusion of radioactive substances released from a smokestack. Smoke containing radioactive substances, or radioactive plume, diffuses into air while being affected by atmospheric turbulent flows in various ways depending on the scale of the plume. The diffusion of a radioactive plume released from a smokestack is discussed first, focusing on the diffusion process in the vicinity of the smokestack, in the atmospheric boundary layer and in the troposphere. Many theoretical studies have been conducted by using the Gaussian plume model, though it is too simple to take into account the topographic effects and unstationary atmospheric conditions. Various numerical calculation models (designed for numerical calculation by a computer) have recently been developed, particularly for the implementation of environmental impact evaluation. Diagnostic and forecast type models are available for atmospheric air flow calculation. Other models available for diffusion analysis include the puff model, segment model, PIC (particle in cell)model, and random walk model. (N.K.)

  18. An atmospheric electrical method to determine the eddy diffusion ...

    Indian Academy of Sciences (India)

    Keywords. Atmospheric electrical profiles; electrode layer; ion–aerosol balance equations. ... eddy diffusion theory (K-theory) in our model equations. K-theory is appropriate for near neutral ...... limit of strong turbulent mixing; J. Geophys. Res.

  19. The chemical evolution of white dwarf atmospheres: Diffusion and accretion

    International Nuclear Information System (INIS)

    Vauclair, G.; Vauclair, S.; Greenstein, J.L.

    1979-01-01

    A study of diffusion processes in white dwarfs is presented. We are especially interested in the estimate of the diffusion time scales for C, N, O, Mg, and Ca along the cooling sequence. The effect of the radiative acceleration is important in hot white dwarfs while in cooler ones the thermal diffusion dominates the gravitational settling. In hot white dwarfs, there should be an observable amount of CNO elements unless they have previously left the stars by a selective wind. Observational tests of this result are discussed. The diffusion time scales are always short compared to the evolutionary time scales. It is shown that in both hydrogen and helium envelopes, the convection zone, even at its maximum depth, is not able to bring back to the stellar surface the metals which have previously diffused downwards. The diffusion alone predicts a complete absence of metals in white dwarf atmospheres and envelopes. As metals are observed in white dwarfs, at least at effective temperatures lower than 15,000 K, there must be some mechanism competing with diffusion. We investigate the competition between diffusion and accretion and propose a general scheme for the chemical evolution of white dwarf atmospheres along the cooling sequence. (orig.)

  20. Modeling Effectivity of Atmospheric Advection-Diffusion Processes

    International Nuclear Information System (INIS)

    Brojewski, R.

    1999-01-01

    Some methods of solving the advection-diffusion problems useful in the field of atmospheric physics are presented and analyzed in the paper. The most effective one ( from the point of view of computer applications) was chosen. This is the method of problem decomposition with respect to the directions followed by secondary decomposition of the problem with respect to the physical phenomena. Introducing some corrections to the classical numerical methods of solving the problems, a hybrid composed of the finite element method for the advection problems and the implicit method with averaging for the diffusion processes was achieved. This hybrid method and application of the corrections produces a very effective means for solving the problems of substance transportation in atmosphere. (author)

  1. Atmospheric turbidity and the diffuse irradiance in Lagos, Nigeria

    International Nuclear Information System (INIS)

    Maduekwe, A.A.L.; Chendo, M.A.C.

    1994-06-01

    The relationships between the total hemispherical irradiance reaching the earth surface in Lagos, Nigeria and the turbidity coefficients at two wavelengths namely λ(500) and λ(880) measured with a Volz sun photometer have been investigated. Using simple piecewise linear regression relationships between the atmospheric turbidity using Angstrom turbidity coefficients and the diffuse components of solar radiation are presented. (author). 18 refs, 11 figs, 3 tabs

  2. Improvement of wind tunnel experiment method for atmospheric diffusion

    International Nuclear Information System (INIS)

    Nakai, Masayuki; Sada, Koichi

    1987-01-01

    A wind direction fluctuation vane was added to CRIEPI's large - scale atmospheric diffusion wind tunnel for the purpose of increasing and controlling turbulence intensity. When the wind direction fluctuation vane was operated lateral plume spread and lateral turbulence intersity became greater than for cases when it was not operated. Use of the vane improved the ability of the wind tunnel to simulate plane spread under natural conditions. (author)

  3. Diffusion from a point source in an urban atmosphere

    International Nuclear Information System (INIS)

    Essa, K.S.M.; El-Otaify, M.S.

    2005-01-01

    In the present paper, a model for the diffusion of material from a point source in an urban atmosphere is incorporated. The plume is assumed to have a well-defined edge at which the concentration falls to zero. The vertical wind shear is estimated using logarithmic law, by employing most of the available techniques of stability categories. The concentrations estimated from the model were compared favorably with the field observations of other investigators

  4. Measurements and theoretical calculations of diffused radiation and atmosphere lucidity

    International Nuclear Information System (INIS)

    Pelece, I.; Iljins, U.; Ziemelis, I.

    2009-01-01

    Align with other environment friendly renewable energy sources solar energy is widely used in the world. Also in Latvia solar collectors are used. However, in Latvia because of its geographical and climatic conditions there are some specific features in comparison with traditional solar energy using countries. These features lead to the necessity to pay more attention to diffused irradiance. Another factor affecting the received irradiance of any surface is lucidity of atmosphere. This factor has not been studied in Latvia yet. This article deals with evaluation of diffused irradiance, and also of lucidity of atmosphere. The diffused irradiance can be measured directly or as a difference between the global irradiance and the beam one. The lucidity of atmosphere can be calculated from the measurements of both global and beam irradiance, if the height of the sun is known. Therefore, measurements of both global and beam irradiance have been carried out, and the diffused irradiance calculated as a difference between the global irradiance and the beam one. For measuring of the global irradiance the dome solarimeter has been used. For measuring of the direct irradiance tracking to sun pirheliometer has been used. The measurements were performed in Riga from October 2008 till March 2009. The measurements were executed automatically after every 5 minutes. The obtained results have been analyzed taking into account also the data on nebulosity from the State agency Latvian Environment, Geology and Meteorology Agency. Also efforts to calculate theoretically the diffused irradiance from the height of the sun and the data of the nebulosity have been done. These calculated values have been compared with the measured ones. Good accordance is obtained. (author)

  5. Persistency of atmospheric diffusion conditions in Angra dos Reis - Brazil

    International Nuclear Information System (INIS)

    Nicolli, D.

    1981-12-01

    Based on a 2 year observation period, the diffusion conditions at the Almirante Alvaro Alberto N.P.P. site, in Angra dos Reis, are analized with respect to persistency as a function of the wind direction, the Pasquill stability class and the time of the day. The Pasquill stability class relates to the bulk vertical temperature gradient measured between 2m and 50m in the atmosphere; the wind direction is measured at 50m height. The persistency is defined in this report as the probability that the wind direction will remain longer than a given time in a sector without change in the diffusion category by more than a certain stage. During the day the persistency is mostly affected by the sea breeze with predominance of the unstable and neutral categories. At night the stable categories dominate. The alternating sea and land breezes disturb daily the trade wind field resulting in low persistency of the diffusion conditions. (Author) [pt

  6. THE LOS ALAMOS NATIONAL LABORATORY ATMOSPHERIC TRANSPORT AND DIFFUSION MODELS

    Energy Technology Data Exchange (ETDEWEB)

    M. WILLIAMS [and others

    1999-08-01

    The LANL atmospheric transport and diffusion models are composed of two state-of-the-art computer codes. The first is an atmospheric wind model called HOThlAC, Higher Order Turbulence Model for Atmospheric circulations. HOTMAC generates wind and turbulence fields by solving a set of atmospheric dynamic equations. The second is an atmospheric diffusion model called RAPTAD, Random Particle Transport And Diffusion. RAPTAD uses the wind and turbulence output from HOTMAC to compute particle trajectories and concentration at any location downwind from a source. Both of these models, originally developed as research codes on supercomputers, have been modified to run on microcomputers. Because the capability of microcomputers is advancing so rapidly, the expectation is that they will eventually become as good as today's supercomputers. Now both models are run on desktop or deskside computers, such as an IBM PC/AT with an Opus Pm 350-32 bit coprocessor board and a SUN workstation. Codes have also been modified so that high level graphics, NCAR Graphics, of the output from both models are displayed on the desktop computer monitors and plotted on a laser printer. Two programs, HOTPLT and RAPLOT, produce wind vector plots of the output from HOTMAC and particle trajectory plots of the output from RAPTAD, respectively. A third CONPLT provides concentration contour plots. Section II describes step-by-step operational procedures, specifically for a SUN-4 desk side computer, on how to run main programs HOTMAC and RAPTAD, and graphics programs to display the results. Governing equations, boundary conditions and initial values of HOTMAC and RAPTAD are discussed in Section III. Finite-difference representations of the governing equations, numerical solution procedures, and a grid system are given in Section IV.

  7. Development of regional meteorological and atmospheric diffusion simulation system

    International Nuclear Information System (INIS)

    Kubota, Ryuji; Iwashige, Kengo; Kasano, Toshio

    2002-01-01

    Regional atmospheric diffusion online network (RADON) with atmospheric diffusion analysis code (ADAC) : a simulation program of diffusion of radioactive materials, volcanic ash, pollen, NOx and SOx was developed. This system can be executed in personal computer (PC) and note PC on Windows. Emission data consists of online, offline and default data. It uses the meteorology data sources such as meteorological forecasting mesh data, automated meteorological data acquisition system (AMeDAS) data, meteorological observation data in site and municipality observation data. The meteorological forecasting mesh data shows forecasting value of temperature, wind speed, wind direction and humidity in about two days. The nuclear environmental monitoring center retains the online data (meteorological data, emission source data, monitoring station data) in its PC server and can run forecasting or repeating calculation using these data and store and print out the calculation results. About 30 emission materials can be calculated simultaneously. This system can simulate a series of weather from the past and real time to the future. (S.Y.)

  8. Atmospheric Diffusion Investigations at Studsvik and Aagesta 1960-1963

    Energy Technology Data Exchange (ETDEWEB)

    Haeggblom, L E; Gyllander, Ch; Widemo, U

    1969-12-15

    During the years 1960-1963 an extensive research programme concerning diffusion behaviour in air was carried out at Studsvik and Agesta. The cost, setting up, operation and experimental part was born by AB Atomenergi (the Swedish atomic energy company) while the Swedish Meteorological and Hydrological Institute (SMHI) processed the results and did the scientific analysis. The following report is a revision and amplification of the material which was presented in internal half-yearly reports from SMHI and in Docent Ulf Hoegstroems dissertation 'An experimental study on atmospheric diffusion'. The chief aim of this report is to make this material available by means of diagrams and tables. Values for diffusion parameters {sigma}{sub z} and {sigma}{sub y} and the resulting concentration-distribution in plumes are shown for different weather conditions during a release period of 1 h, for stack heights of 25, 50, 75 and 100 m and for release at ground level. The method and calculation principles are described, and different factors such as the stability parameter {lambda}, the effect of the stack and the width of the plume are presented. The data is also used for calculating release from buildings and for diffusion for short sampling periods.

  9. Atmospheric Diffusion Investigations at Studsvik and Aagesta 1960-1963

    International Nuclear Information System (INIS)

    Haeggblom, L.E.; Gyllander, Ch.; Widemo, U.

    1969-12-01

    During the years 1960-1963 an extensive research programme concerning diffusion behaviour in air was carried out at Studsvik and Agesta. The cost, setting up, operation and experimental part was born by AB Atomenergi (the Swedish atomic energy company) while the Swedish Meteorological and Hydrological Institute (SMHI) processed the results and did the scientific analysis. The following report is a revision and amplification of the material which was presented in internal half-yearly reports from SMHI and in Docent Ulf Hoegstroems dissertation 'An experimental study on atmospheric diffusion'. The chief aim of this report is to make this material available by means of diagrams and tables. Values for diffusion parameters σ z and σ y and the resulting concentration-distribution in plumes are shown for different weather conditions during a release period of 1 h, for stack heights of 25, 50, 75 and 100 m and for release at ground level. The method and calculation principles are described, and different factors such as the stability parameter λ, the effect of the stack and the width of the plume are presented. The data is also used for calculating release from buildings and for diffusion for short sampling periods

  10. Rancho Seco building wake effects on atmospheric diffusion

    International Nuclear Information System (INIS)

    Start, G.E.; Cate, J.H.; Dickson, C.R.; Ricks, N.R.; Ackerman, G.R.; Sagendorf, J.F.

    1977-11-01

    A series of 23 paired gaseous tracer releases at the Rancho Seco Nuclear Power Station in 1975 was the third of several tests designed to investigate the diffusion characteristics of the atmosphere under conditions of low windspeed and temperature inversion. This test also evaluated the effects of flow around buildings upon dilution of pollutants. Gaseous tracers were laterally dispersed about six times more than the expected amounts from Pasquill--Gifford curves of sigma-y. Most of this increase could be related to observed variance of the horizontal wind direction (meandering). For ground-level releases the effective sigma-z values were 16 times greater than the corresponding values from the Pasquill--Gifford curves. Measured ground-level axial concentrations were about 75 times smaller than predicted by the Gaussian diffusion equation for a ground-level release when Pasquill--Gifford values of sigma-y and sigma-z were used

  11. Some basic mathematical methods of diffusion theory. [emphasis on atmospheric applications

    Science.gov (United States)

    Giere, A. C.

    1977-01-01

    An introductory treatment of the fundamentals of diffusion theory is presented, starting with molecular diffusion and leading up to the statistical methods of turbulent diffusion. A multilayer diffusion model, designed to permit concentration and dosage calculations downwind of toxic clouds from rocket vehicles, is described. The concepts and equations of diffusion are developed on an elementary level, with emphasis on atmospheric applications.

  12. Implicit coupling of turbulent diffusion with chemical reaction mechanisms for prognostic atmospheric dispersion models

    Energy Technology Data Exchange (ETDEWEB)

    Berlowitz, D.R.

    1996-11-01

    In the last few decades the negative impact by humans on the thin atmospheric layer enveloping the earth, the basis for life on this planet, has increased steadily. In order to halt, or at least slow down this development, the knowledge and study of these anthropogenic influence has to be increased and possible remedies have to be suggested. An important tool for these studies are computer models. With their help the atmospheric system can be approximated and the various processes, which have led to the current situation can be quantified. They also serve as an instrument to assess short or medium term strategies to reduce this human impact. However, to assure efficiency as well as accuracy, a careful analysis of the numerous processes involved in the dispersion of pollutants in the atmosphere is called for. This should help to concentrate on the essentials and also prevent excessive usage of sometimes scarce computing resources. The basis of the presented work is the EUMAC Zooming Model (ETM), and particularly the component calculating the dispersion of pollutants in the atmosphere, the model MARS. The model has two main parts: an explicit solver, where the advection and the horizontal diffusion of pollutants are calculated, and an implicit solution mechanism, allowing the joint computation of the change of concentration due to chemical reactions, coupled with the respective influence of the vertical diffusion of the species. The aim of this thesis is to determine particularly the influence of the horizontal components of the turbulent diffusion on the existing implicit solver of the model. Suggestions for a more comprehensive inclusion of the full three dimensional diffusion operator in the implicit solver are made. This is achieved by an appropriate operator splitting. A selection of numerical approaches to tighten the coupling of the diffusion processes with the calculation of the applied chemical reaction mechanisms are examined. (author) figs., tabs., refs.

  13. Hanford 67-series: a volume of atmospheric field diffusion measurements

    International Nuclear Information System (INIS)

    Nickola, P.W.

    1977-11-01

    This volume documents atmospheric diffusion experiments carried out at the Hanford reservation during the period 1967 to 1973. A total of 103 tracer releases during 54 release periods is tabulated. Multi-tracer releases (generally from different elevations) were made during most of the experimental periods. Release heights varied from ground level to an elevation of 111 m. Tracers were sampled simultaneously on as many as 10 arcs at distances of up to 12.8 km from the tracer release point. As many as 718 field sampling locations were employed during some of the experiments. Vertical profiles of concentration were monitored on towers during 23 of the 54 release periods. Concurrent vertical profiles of mean temperature, of mean wind speed and direction, and of direction standard deviation are also tabled for elevations up to 122 m

  14. Solutions for a diffusion equation with a backbone term

    International Nuclear Information System (INIS)

    Tateishi, A A; Lenzi, E K; Ribeiro, H V; Evangelista, L R; Mendes, R S; Da Silva, L R

    2011-01-01

    We investigate the diffusion equation ∂ t ρ=D y ∂ y 2 ρ+D x ∂ x 2 ρ+ D-bar x δ(y)∂ x μ ρ subjected to the boundary conditions ρ(±∞,y;t)=0 and ρ(x,±∞;t)=0, and the initial condition ρ(x,y;0)= ρ-hat (x,y). We obtain exact solutions in terms of the Green function approach and analyze the mean square displacement in the x and y directions. This analysis shows an anomalous spreading of the system which is characterized by different diffusive regimes connected to anomalous diffusion

  15. Grain boundary diffusion in terms of the tempered fractional calculus

    Energy Technology Data Exchange (ETDEWEB)

    Sibatov, R.T., E-mail: ren_sib@bk.ru [Ulyanovsk State University, 432017, 42 Leo Tolstoy str., Ulyanovsk (Russian Federation); Svetukhin, V.V. [Ulyanovsk State University, 432017, 42 Leo Tolstoy str., Ulyanovsk (Russian Federation); Institute of Nanotechnology and Microelectronics of the Russian Academy of Sciences, 115487, 18 Nagatinskaya str., Moscow (Russian Federation)

    2017-06-28

    Mathematical treatment of grain-boundary diffusion based on the model first proposed by Fisher is usually formulated in terms of normal diffusion equations in a two-component nonhomogeneous medium. On the other hand, fractional equations of anomalous diffusion proved themselves to be useful in description of grain-boundary diffusion phenomena. Moreover, the most important propagation regime predicted by Fisher's model demonstrates subdiffusive behavior. However, the direct link between fractional approach and the Fisher model and its modifications has not found yet. Here, we fill this gap and show that solution of fractional subdiffusion equation offers general properties of classical solutions obtained by Whipple and Suzuoka. The tempered fractional approach is a convenient tool for studying precipitation in granular materials as the tempered subdiffusion limited process. - Highlights: • The link connected fractional diffusion approach and Fisher's model of grain-boundary diffusion is derived. • The subdiffusion exponent of grain-boundary diffusion can differ from 1/2. • Nucleation in granular materials is modeled by the process limited by tempered subdiffusion.

  16. Grain boundary diffusion in terms of the tempered fractional calculus

    International Nuclear Information System (INIS)

    Sibatov, R.T.; Svetukhin, V.V.

    2017-01-01

    Mathematical treatment of grain-boundary diffusion based on the model first proposed by Fisher is usually formulated in terms of normal diffusion equations in a two-component nonhomogeneous medium. On the other hand, fractional equations of anomalous diffusion proved themselves to be useful in description of grain-boundary diffusion phenomena. Moreover, the most important propagation regime predicted by Fisher's model demonstrates subdiffusive behavior. However, the direct link between fractional approach and the Fisher model and its modifications has not found yet. Here, we fill this gap and show that solution of fractional subdiffusion equation offers general properties of classical solutions obtained by Whipple and Suzuoka. The tempered fractional approach is a convenient tool for studying precipitation in granular materials as the tempered subdiffusion limited process. - Highlights: • The link connected fractional diffusion approach and Fisher's model of grain-boundary diffusion is derived. • The subdiffusion exponent of grain-boundary diffusion can differ from 1/2. • Nucleation in granular materials is modeled by the process limited by tempered subdiffusion.

  17. Long-term calibration monitoring of Spectralon diffusers BRDF in the air-ultraviolet.

    Science.gov (United States)

    Georgiev, Georgi T; Butler, James J

    2007-11-10

    Long-term calibration monitoring of the bidirectional reflectance distribution function (BRDF) of Spectralon diffusers in the air-ultraviolet is presented. Four Spectralon diffusers were monitored in this study. Three of the diffusers, designated as H1, H2, and H3, were used in the prelaunch radiance calibration of the Solar Backscatter Ultraviolet/2 (SBUV/2) satellite instruments on National Oceanic and Atmospheric Administration (NOAA) 14 and 16. A fourth diffuser, designated as the 400 diffuser, was used in the prelaunch calibration of the Ozone Mapping and Profiler Suite (OMPS) instrument scheduled for initial flight in 2009 on the National Polar Orbiting Environmental Satellite System Preparatory Project. The BRDF data of this study were obtained between 1994 and 2005 using the scatterometer located in the National Aeronautics and Space Administration Goddard Space Flight Center Diffuser Calibration Laboratory. The diffusers were measured at 13 wavelengths between 230 and 425 nm at the incident and scatter angles used in the prelaunch calibrations of SBUV/2 and OMPS. Spectral features in the BRDF of Spectralon are also discussed. The comparison shows how the air-ultraviolet BRDF of these Spectralon samples changed over time under clean room deployment conditions.

  18. An alternative atmospheric diffusion model for control room habitability assessments

    International Nuclear Information System (INIS)

    Ramsdell, J.V. Jr.

    1990-01-01

    The US Nuclear Regulatory (NRC) staff uses procedures to evaluate control room designs for compliance with General Design Criterion 19 of the Code of Federal Regulations, Appendix A, 10 CRF Part 50. These procedures deal primarily with radiation protection. However, other hazardous materials, for example, chlorine, pose a potential threat to control room habitability. The NRC is considering changes in their current procedures to update methods and extend their applicability. Two changes to the current procedures are suggested: using a puff diffusion model to estimate concentrations at air intakes and using a new method to estimate diffusion coefficients

  19. Effects on atmospheric diffusion of meterological processes in coastal zones

    International Nuclear Information System (INIS)

    Raynor, G.S.

    1977-01-01

    Meteorological processes in coastal zones differ from those inland because of the surface discontinuity between land and water. The difference in heating between the two surfaces gives rise to sea or lake breeze circulations which can transport pollutants in nongradient directions and recirculate them over source areas. The step change in surface characteristics at the land-water interface also causes formation of internal boundary layers having different transport velocities and diffusion rates than unmodified air upwind or above the boundary. These features require a more extensive measurement program and more versatile diffusion models than at inland sites

  20. Evaluation of carbon diffusion in heat treatment of H13 tool steel under different atmospheric conditions

    OpenAIRE

    Ramezani, Maziar; Pasang, Timotius; Chen, Zhan; Neitzert, Thomas; Au, Dominique

    2015-01-01

    Although the cost of the heat treatment process is only a minor portion of the total production cost, it is arguably the most important and crucial stage on the determination of material quality. In the study of the carbon diffusion in H13 steel during austenitization, a series of heat treatment experiments had been conducted under different atmospheric conditions and length of treatment. Four austenitization atmospheric conditions were studied, i.e., heat treatment without atmospheric contro...

  1. Evaluation of the impact of atmospheric ozone and aerosols on the horizontal global/diffuse UV Index at Livorno (Italy)

    Science.gov (United States)

    Scaglione, Daniele; Giulietti, Danilo; Morelli, Marco

    2016-08-01

    A study was conducted at Livorno (Italy) to evaluate the impact of atmospheric aerosols and ozone on the solar UV radiation and its diffuse component at ground in clear sky conditions. Solar UV radiation has been quantified in terms of UV Index (UVI), following the ISO 17166:1999/CIE S007/E-1998 international standard. UVI has been calculated by exploiting the libRadtran radiative transfer modelling software as a function of both the Aerosols Optical Depth (AOD) and the Total Ozone Column (TOC). In particular AOD and TOC values have been remotely sensed by the Ozone Monitoring Instrument (OMI) on board the NASA's EOS (Earth Observing System) satellites constellation. An experimental confirmation was also obtained by exploiting global UVI ground-based measurements from the 26/9/14 to 12/8/15 and diffuse UVI ground-based measurements from the 17/5/15 to 12/8/15. For every considered value of Solar Zenith Angle (SZA) and atmospheric condition, estimates and measurements confirm that the diffuse component contributes for more than 50% on the global UV radiation. Therefore an exposure of human skin also to diffuse solar UV radiation can be potentially harmful for health and need to be accurately monitored, e.g. by exploiting innovative applications such as a mobile app with a satellite-based UV dosimeter that has been developed. Global and diffuse UVI variations due to the atmosphere are primarily caused by the TOC variations (typically cyclic): the maximum TOC variation detected by OMI in the area under study leads to a corresponding variation in global and diffuse UVI of about 50%. Aerosols in the area concerned, mainly of maritime nature, have instead weaker effects causing a maximum variation of the global and diffuse UVI respectively of 9% and 35% with an SZA of 20° and respectively of 13% and 10% with an SZA of 60°.

  2. Similarity solutions of reaction–diffusion equation with space- and time-dependent diffusion and reaction terms

    Energy Technology Data Exchange (ETDEWEB)

    Ho, C.-L. [Department of Physics, Tamkang University, Tamsui 25137, Taiwan (China); Lee, C.-C., E-mail: chieh.no27@gmail.com [Center of General Education, Aletheia University, Tamsui 25103, Taiwan (China)

    2016-01-15

    We consider solvability of the generalized reaction–diffusion equation with both space- and time-dependent diffusion and reaction terms by means of the similarity method. By introducing the similarity variable, the reaction–diffusion equation is reduced to an ordinary differential equation. Matching the resulting ordinary differential equation with known exactly solvable equations, one can obtain corresponding exactly solvable reaction–diffusion systems. Several representative examples of exactly solvable reaction–diffusion equations are presented.

  3. DIFFUSE DBD IN ATMOSPHERIC AIR AT DIFFERENT APPLIED PULSE WIDTHS

    Directory of Open Access Journals (Sweden)

    Ekaterina Alexandrovna Shershunova

    2015-02-01

    Full Text Available The paper deals with the realization and the diagnostics of the volume diffuse dielectric barrier discharge in 1-mm air gap when applying high voltage rectangular pulses to the electrodes. The effect of the applied pulse width on the discharge dissipated energy was studied in detail. It was found experimentally, the energy stayed nearly constant with the pulse elongation from 600 ns to 1 ms.

  4. Long-term atmospheric corrosion of mild steel

    International Nuclear Information System (INIS)

    Fuente, D. de la; Diaz, I.; Simancas, J.; Chico, B.; Morcillo, M.

    2011-01-01

    Research highlights: → Atmospheric corrosion rate stabilises after the first 4-6 years of exposure. → Great compaction of the rust layers in rural and urban atmospheres. → Corrosion (in rural and urban) deviates from common behaviour of bilogarithmic law. → Typical structures of lepidocrocite, goethite and akaganeite are identified. → Formation of hematite (industrial atmosphere) and ferrihydrite (marine atmosphere). - Abstract: A great deal of information is available on the atmospheric corrosion of mild steel in the short, mid and even long term, but studies of the structure and morphology of corrosion layers are less abundant and generally deal with those formed in just a few years. The present study assesses the structure and morphology of corrosion product layers formed on mild steel after 13 years of exposure in five Spanish atmospheres of different types: rural, urban, industrial and marine (mild and severe). The corrosion layers have been characterised by X-ray diffraction (XRD) and scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS). Long-term corrosion is seen to be more severe in the industrial and marine atmospheres, and less so in the rural and urban atmospheres. In all cases the corrosion rate is seen to decrease with exposure time, stabilising after the first 4-6 years of exposure. The most relevant aspects to be noted are (a) the great compaction of the rust layers formed in the rural and urban atmospheres, (b) the formation of hematite and ferrihydrite phases (not commonly found) in the industrial and marine atmospheres, respectively and (c) identification of the typical morphological structures of lepidocrocite (sandy crystals and flowery plates), goethite (cotton balls structures) and akaganeite (cotton balls structures and cigar-shaped crystals).

  5. The characteristic features of the atmospheric diffusion of pollutants

    International Nuclear Information System (INIS)

    Schultz, H.

    1986-01-01

    The publication facilitates access to the development and effects of air pollution caused by the major emission sources by way of discussing the atmospheric dispersion of pollutants and the processes involved. Apart from the physical ratings of atmospheric pollutants the author focuses on the meteorological parameters determining the dispersion process as well as on the unavoidable statistical variations. Representative realistic maximum and minimum values indicating the relation between emissions from the relevant sources and the resulting air pollution allow an expeditious evaluation of possible environmental impacts classified by the different types of pollutants. The publication not only discusses the direct incorporation, that is the breathing of contaminated air or the absorption of food grown or produced in contaminated regions but also refers to radiation doses which due to the presence of radioactive substances accumulate in the human organism. Comprehensive references are annexed to facilitate access to relevant problems connected with the subject discussed. (orig./HP) [de

  6. A study of atmospheric diffusion from the LANDSAT imagery. [pollution transport over the ocean

    Science.gov (United States)

    Dejesusparada, N. (Principal Investigator); Viswanadham, Y.; Torsani, J. A.

    1981-01-01

    LANDSAT multispectral scanner data of the smoke plumes which originated in eastern Cabo Frio, Brazil and crossed over into the Atlantic Ocean, are analyzed to illustrate how high resolution LANDSAT imagery can aid meteorologists in evaluating specific air pollution events. The eleven LANDSAT images selected are for different months and years. The results show that diffusion is governed primarily by water and air temperature differences. With colder water, low level air is very stable and the vertical diffusion is minimal; but water warmer than the air induces vigorous diffusion. The applicability of three empirical methods for determining the horizontal eddy diffusivity coefficient in the Gaussian plume formula was evaluated with the estimated standard deviation of the crosswind distribution of material in the plume from the LANDSAT imagery. The vertical diffusion coefficient in stable conditions is estimated using Weinstock's formulation. These results form a data base for use in the development and validation of meso scale atmospheric diffusion models.

  7. Atmospheric diffusion model for control room habitability assessments

    International Nuclear Information System (INIS)

    Ramsdell, J.V.; Lee, J.Y.

    1993-01-01

    General Design Criterion 19 for nuclear power plants (Appendix A to 10CFR50) requires control room radiation protection adequate to limit radiation exposures to control room personnel. Murphy and Campe proposed the procedure currently used in evaluating control room habitability. However, data from building-wake diffusion experiments at nuclear power plants indicate that the Murphy-Campe procedure tends to overestimate concentrations, particularly during low wind speeds. This paper describes an alternative procedure developed by the Pacific Northwest Laboratory that is acceptable to U.S. Nuclear Regulatory Commission (NRC) staff. The procedure estimates control room air intake concentrations that are generally lower than those estimated by the Murphy-Campe procedure, yet are still conservative

  8. Cleaning of niobium surface by plasma of diffuse discharge at atmospheric pressure

    Science.gov (United States)

    Tarasenko, V. F.; Erofeev, M. V.; Shulepov, M. A.; Ripenko, V. S.

    2017-07-01

    Elements composition of niobium surface before and after plasma treatment by runaway electron preionized diffuse discharge was investigated in atmospheric pressure nitrogen flow by means of an Auger electron spectroscopy. Surface characterizations obtained from Auger spectra show that plasma treatment by diffuse discharge after exposure of 120000 pulses provides ultrafine surface cleaning from carbon contamination. Moreover, the surface free energy of the treated specimens increased up to 3 times, that improve its adhesion property.

  9. Atmospheric diffusion at coastal site in presence of sea-breeze

    International Nuclear Information System (INIS)

    Messaci, M.

    1987-03-01

    The coastal sites present special features so much by the dominant wind system then by the lower layers of the atmosphere. Two types of experiments were handled on a coastal site in presence of sea breeze. First, vertical atmospheric sounding by radiosounding and by throwing experimental balloons; then the discharge of tracer: the SF6. The first experiment lead us to put in a prominent position the Internal Boundary Layer and the determination of its height. Whereas the second experiment allowed us to estimate the diffusion parameters of the site as well as to obtain interesting conclusions on diffusivity of the environment studied and the influence of certain factors

  10. Maxwell-Stefan diffusion: a framework for predicting condensed phase diffusion and phase separation in atmospheric aerosol

    Science.gov (United States)

    Fowler, Kathryn; Connolly, Paul J.; Topping, David O.; O'Meara, Simon

    2018-02-01

    The composition of atmospheric aerosol particles has been found to influence their micro-physical properties and their interaction with water vapour in the atmosphere. Core-shell models have been used to investigate the relationship between composition, viscosity and equilibration timescales. These models have traditionally relied on the Fickian laws of diffusion with no explicit account of non-ideal interactions. We introduce the Maxwell-Stefan diffusion framework as an alternative method, which explicitly accounts for non-ideal interactions through activity coefficients. e-folding time is the time it takes for the difference in surface and bulk concentration to change by an exponential factor and was used to investigate the interplay between viscosity and solubility and the effect this has on equilibration timescales within individual aerosol particles. The e-folding time was estimated after instantaneous increases in relative humidity to binary systems of water and an organic component. At low water mole fractions, viscous effects were found to dominate mixing. However, at high water mole fractions, equilibration times were more sensitive to a range in solubility, shown through the greater variation in e-folding times. This is the first time the Maxwell-Stefan framework has been applied to an atmospheric aerosol core-shell model and shows that there is a complex interplay between the viscous and solubility effects on aerosol composition that requires further investigation.

  11. Low-temperature hydrogenation of diamond nanoparticles using diffuse coplanar surface barrier discharge at atmospheric pressure

    Czech Academy of Sciences Publication Activity Database

    Kromka, Alexander; Čech, J.; Kozak, Halyna; Artemenko, Anna; Ižák, Tibor; Čermák, Jan; Rezek, Bohuslav; Černák, M.

    2015-01-01

    Roč. 252, č. 11 (2015), s. 2602-2607 ISSN 0370-1972 R&D Projects: GA ČR(CZ) GBP108/12/G108 Institutional support: RVO:68378271 Keywords : atmospheric plasma * diamond nanoparticles * diffuse coplanar surface barrier discharge * FTIR * XPS Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.522, year: 2015

  12. Diffuse plasma treatment of polyamide 66 fabric in atmospheric pressure air

    International Nuclear Information System (INIS)

    Li, Lee; Peng, Ming-yang; Teng, Yun; Gao, Guozhen

    2016-01-01

    Graphical abstract: - Highlights: • A cylindrical-electrode nanosecond-pulse diffuse-discharge reactor is presented. • Large-scale non-thermal plasmas were generated steadily in atmospheric air. • Treated PA66 fabric is etched with oxygen-containing group increases. • The hydrophily of treated PA66 fabric improves effectively. • Extending the treatment time is a method to reduce the treatment frequency. - Abstract: The polyamide 66 (PA66) fabrics are hard to be colored or glued in industrial production due to the poor hydrophily. Diffuse plasma is a kind of non-thermal plasma generated at atmospheric pressure in air. This paper proposes that large-scale diffuse plasma generated between wire electrodes can be employed for improving the hydrophily of PA66 fabrics. A repetitive nanosecond-pulse diffuse-discharge reactor using a cylindrical wire electrode configuration is presented, which can generate large-scale non-thermal plasmas steadily at atmospheric pressure without any barrier dielectric. Then the reactor is used to treat PA66 fabrics in different discharge conditions. The hydrophilicity property of modified PA66 is measured by wicking test method. The modified PA66 is also analyzed by atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) to prove the surface changes in physical microstructure and chemical functional groups, respectively. What's more, the effects of treatment time and treatment frequency on surface modification are investigated and discussed.

  13. Chernobyl source term, atmospheric dispersion, and dose estimation

    International Nuclear Information System (INIS)

    Gudiksen, P.H.; Harvey, T.F.; Lange, R.

    1988-02-01

    The Chernobyl source term available for long-range transport was estimated by integration of radiological measurements with atmospheric dispersion modeling, and by reactor core radionuclide inventory estimation in conjunction with WASH-1400 release fractions associated with specific chemical groups. These analyses indicated that essentially all of the noble gases, 80% of the radioiodines, 40% of the radiocesium, 10% of the tellurium, and about 1% or less of the more refractory elements were released. Atmospheric dispersion modeling of the radioactive cloud over the Northern Hemisphere revealed that the cloud became segmented during the first day, with the lower section heading toward Scandinavia and the uppper part heading in a southeasterly direction with subsequent transport across Asia to Japan, the North Pacific, and the west coast of North America. The inhalation doses due to direct cloud exposure were estimated to exceed 10 mGy near the Chernobyl area, to range between 0.1 and 0.001 mGy within most of Europe, and to be generally less than 0.00001 mGy within the US. The Chernobyl source term was several orders of magnitude greater than those associated with the Windscale and TMI reactor accidents, while the 137 Cs from the Chernobyl event is about 6% of that released by the US and USSR atmospheric nuclear weapon tests. 9 refs., 3 figs., 6 tabs

  14. Diffusion coefficients in 4-component mixture expressed explicitly in terms of binary diffusion coefficients and mole fractions

    International Nuclear Information System (INIS)

    Furuta, Hiroshi; Yamamoto, Ichiro

    1996-01-01

    Diffusion coefficients in 4-component mixture D ij (4) were expressed explicitly in terms of binary diffusion coefficients and mole fractions by solving a ratio of determinants defined by Hirschfelder et al. The explicit expressions of D ij (4) were divided into two terms, a term due to the i-j pairs of attention and a term common to all the pairs out of the 4 components. The two terms of D ij (4) had extended structures similar to corresponding those of D ij (3) respectively. (author)

  15. Developing a passive trap for diffusive atmospheric {sup 14}CO{sub 2} sampling

    Energy Technology Data Exchange (ETDEWEB)

    Walker, Jennifer C.; Xu, Xiaomei [Department of Earth System Science, University of California, Irvine, Irvine, CA (United States); Fahrni, Simon M. [Department of Earth System Science, University of California, Irvine, Irvine, CA (United States); Institute of Particle Physics, ETH, Zurich (Switzerland); Lupascu, Massimo [Department of Earth System Science, University of California, Irvine, Irvine, CA (United States); Department of Geography, National University of Singapore (Singapore); Czimczik, Claudia I. [Department of Earth System Science, University of California, Irvine, Irvine, CA (United States)

    2015-10-15

    {sup 14}C-CO{sub 2} measurement is an unique tool to quantify source-based emissions of CO{sub 2} for both the urban and natural environments. Acquiring a sample that temporally integrates the atmospheric {sup 14}C-CO{sub 2} signature that allows for precise {sup 14}C analysis is often necessary, but can require complex sampling devices, which can be difficult to deploy and maintain, especially for multiple locations. Here we describe our progress in developing a diffusive atmospheric CO{sub 2} molecular sieve trap, which requires no power to operate. We present results from various cleaning procedures, and rigorously tested for blank and memory effects. Traps were tested in the environment along-side conventional sampling flasks for accuracy. Results show that blank and memory effects can be minimized with thorough cleaning and by avoiding overheating, and that diffusively collected air samples agree well with traditionally canister-sampled air.

  16. Application of atmospheric diffusion factor in the bay of east Liaoning

    International Nuclear Information System (INIS)

    Yang Hongbin; Liu Wanjun; Ma Yanjun; Zhao Guozhen

    1999-01-01

    The characteristics of atmospheric diffusion factor in the Bay of East Liaoning are studied using the data obtained from meteorological tower-based sensors at the site located about 800 m from the coast. The results show that the nuclear power station emits pollutants as a high source during its operation. Furthermore, it is found that the lifting level of plume is lower than 30 m when wind speed is greater

  17. Development of an Automated Diffusion Scrubber-Conductometry System for Measuring Atmospheric Ammonia

    International Nuclear Information System (INIS)

    Lee, Bok Young; Lee, Chong Keun; Lee, Dong Soo

    2011-01-01

    A semi-continuous and automated method for quantifying atmospheric ammonia at the parts per billion level has been developed. The instrument consists of a high efficiency diffusion scrubber, an electrolytic on-line anion exchange device, and a conductivity detector. Water soluble gases in sampled air diffuse through the porous membrane and are absorbed in an absorbing solution. Interferences are eliminated by using an anion exchange devises. The electrical conductivity of the solution is measured without chromatographic separation. The collection efficiency was over 99%. Over the 0-200 ppbv concentration range, the calibration was linear with r"2 = 0.99. The lower limit of detection was 0.09 ppbv. A parallel analysis of Seoul air over several days using this method and a diffusion scrubber coupled to an ion chromatography system showed acceptable agreement, r"2 = 0.940 (n = 686). This method can be applied for ambient air monitoring of ammonia

  18. Development of an Automated Diffusion Scrubber-Conductometry System for Measuring Atmospheric Ammonia

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Bok Young; Lee, Chong Keun; Lee, Dong Soo [Yonsei University, Seoul (Korea, Republic of)

    2011-06-15

    A semi-continuous and automated method for quantifying atmospheric ammonia at the parts per billion level has been developed. The instrument consists of a high efficiency diffusion scrubber, an electrolytic on-line anion exchange device, and a conductivity detector. Water soluble gases in sampled air diffuse through the porous membrane and are absorbed in an absorbing solution. Interferences are eliminated by using an anion exchange devises. The electrical conductivity of the solution is measured without chromatographic separation. The collection efficiency was over 99%. Over the 0-200 ppbv concentration range, the calibration was linear with r{sup 2} = 0.99. The lower limit of detection was 0.09 ppbv. A parallel analysis of Seoul air over several days using this method and a diffusion scrubber coupled to an ion chromatography system showed acceptable agreement, r{sup 2} = 0.940 (n = 686). This method can be applied for ambient air monitoring of ammonia.

  19. Diffusion model of solid particles in a gaseous atmosphere. Pt. 1

    International Nuclear Information System (INIS)

    Fernandez Ruiz, J.L.

    1987-01-01

    Starting from Voinov and Garipov's lagrangian statements on the problem of dynamic evolution of bubbles in liquids, this work is trying to determine some diffusion equations of solid particles in little dense matter like gases or liquids, aiming at applying it to the tracing of matter in atmospheric diffusion and the tracing of corpuscles in liquids. All the resulting equations lead to a solution given as a tensor θ ij related to the velocity states v i defined as v i = , and to the potential from which derive. One has had in mind the factor of mutual correlation between the diffusing particles. This increases the scope of application of these equations to Chemistry and to Biomedical Sciences. (author)

  20. Evaluation of carbon diffusion in heat treatment of H13 tool steel under different atmospheric conditions

    Directory of Open Access Journals (Sweden)

    Maziar Ramezani

    2015-04-01

    Full Text Available Although the cost of the heat treatment process is only a minor portion of the total production cost, it is arguably the most important and crucial stage on the determination of material quality. In the study of the carbon diffusion in H13 steel during austenitization, a series of heat treatment experiments had been conducted under different atmospheric conditions and length of treatment. Four austenitization atmospheric conditions were studied, i.e., heat treatment without atmospheric control, heat treatment with stainless steel foil wrapping, pack carburization heat treatment and vacuum heat treatment. The results showed that stainless steel foil wrapping could restrict decarburization process, resulting in a constant hardness profile as vacuum heat treatment does. However, the tempering characteristic between these two heat treatment methods is different. Results from the gas nitrided samples showed that the thickness and the hardness of the nitrided layer is independent of the carbon content in H13 steel.

  1. Effect of growth regulators on 'Brookfield' apple gas diffusion and metabolism under controlled atmosphere storage

    Directory of Open Access Journals (Sweden)

    Auri Brackmann

    2014-05-01

    Full Text Available The objective of this work was to evaluate the effect of growth regulators on gas diffusion and on metabolism of 'Brookfield' apple, and to determine their correlation with quality characteristics of fruit stored in controlled atmosphere. A completely randomized design was used with four replicates. After eight months of storage, the effects of water (control, aminoethoxyvinylglycine (AVG, AVG + ethephon, AVG + naphthaleneacetic acid (NAA, ethephon + NAA, sole NAA, 1-MCP, ethylene absorption by potassium permanganate (ABS, AVG + ABS, and of AVG + 1-MCP - applied at different rates and periods - were evaluated on: gas diffusion rate, ethylene production, respiratory rate, internal ethylene concentration, internal CO2 content, mealiness, and intercellular space. Fruit from the control and sole NAA treatments had the highest mealiness occurrence. Growth regulators significantly changed the gaseous diffusion through the pulp of 'Brookfield' apple, mainly in the treatment AVG + ABS, which kept the highest gas diffusion rate. NAA spraying in the field, with or without another growth regulator, increased ripening metabolism by rising ethylene production and respiration rate, and reduced gas diffusion during shelf life. AVG spraying cannot avoid the ethephon effect during the ripening process, and reduces both the internal space and mealiness incidence, but it is not able to induce ethylene production or to increase respiration rates.

  2. Long-term variation of atmospheric beryllium-7 in Taiwan

    International Nuclear Information System (INIS)

    Yu-Ming Lin; Chi-Chang Liu; Ching-Jiang Chen

    1996-01-01

    Taiwan Radiation Monitoring Center (TRMC) has measured the concentration of atmospheric 7 Be at tile four stations on Taiwan for almost twenty years. Gamma emitting nuclides have been collected by air samplers and measured by gamma spectrometry. Cosmogenic 7 Be and other man-made radionuclides produced by Chinese nuclear weapon testings have been detected. Compared with 7 Be, man-made nuclides vanished quickly because of their short half life. The behaviour of 7 Be in long-term concentration variation is different between northern and southern Taiwan because of local meteorological conditions. Tile results of Fourier analysis show that washout effect of rainfalls and transportation from stratosphere to troposphere are closely related to tile variation of 7Be concentration in near surface air. All the measured data of 7 Be show that tile characteristic of yearly data coincides with tile 11-year solar cycle. (author)

  3. Investigations into exhaust air plume diffusion in the atmosphere. Progress report July 1973 - June 1974. P. 1

    International Nuclear Information System (INIS)

    Vogt, K.J.; Geiss, H.; Horbert, M.; Nordsieck, H.; Polster, G.; Rohloff, F.

    1974-09-01

    The paper is the first part of the status report on the research project 'Diffusion of pollutants in the atmosphere and environmental hazards'. It investigates the diffusion of exhaust air plumes in tracer experiments, thereby continuing the present investigations of the same issue. (orig./AK) [de

  4. assessment of concentration of air pollutants using analytical and numerical solution of the atmospheric diffusion equation

    International Nuclear Information System (INIS)

    Esmail, S.F.H.

    2011-01-01

    The mathematical formulation of numerous physical problems a results in differential equations actually partial or ordinary differential equations.In our study we are interested in solutions of partial differential equations.The aim of this work is to calculate the concentrations of the pollution, by solving the atmospheric diffusion equation(ADE) using different mathematical methods of solution. It is difficult to solve the general form of ADE analytically, so we use some assumptions to get its solution.The solutions of it depend on the eddy diffusivity profiles(k) and the wind speed u. We use some physical assumptions to simplify its formula and solve it. In the present work, we solve the ADE analytically in three dimensions using Green's function method, Laplace transform method, normal mode method and these separation of variables method. Also, we use ADM as a numerical method. Finally, comparisons are made with the results predicted by the previous methods and the observed data.

  5. Diffuse and spot mode of cathode arc attachments in an atmospheric magnetically rotating argon arc

    International Nuclear Information System (INIS)

    Chen, Tang; Wang, Cheng; Liao, Meng-Ran; Xia, Wei-Dong

    2016-01-01

    A model including the cathode, near-cathode region, and arc column was constructed. Specifically, a thermal perturbation layer at the arc fringe was calculated in order to couple sheath/presheath modelling with typical arc column modelling. Comparative investigation of two modes of attachment of a dc (100, 150, 200 A) atmospheric-pressure arc in argon to a thermionic cathode made of pure tungsten was conducted. Computational data revealed that there exists two modes of arc discharge: the spot mode, which has an obvious cathode surface temperature peak in the arc attachment centre; and the diffuse mode, which has a flat cathode surface temperature distribution and a larger arc attachment area. The modelling results of the arc attachment agree with previous experimental observations for the diffuse mode. A further 3D simulation is obviously needed to investigate the non-axisymmetrical features, especially for the spot mode. (paper)

  6. Comparison of low cost measurement techniques for long-term monitoring of atmospheric ammonia.

    Science.gov (United States)

    Sutton, M A; Miners, B; Tang, Y S; Milford, C; Wyers, G P; Duyzer, J H; Fowler, D

    2001-10-01

    An inter-comparison of techniques for long-term sampling of atmospheric ammonia (NH3) was conducted with a view to establishing a national network with > 50 sites. Key requirements were for: a low cost system, simplicity and durability to enable a postal exchange with local site operators, a precision of sampling at expected NH3 concentrations of 1-2 micrograms m-3, a detection limit sufficient to resolve the small NH3 concentrations (sampling methods were compared: A, a commercially available membrane diffusion tube (exposed in triplicate), with membranes removed immediately after sampling; B, the above method, with the membranes left in place until analysis; C, open-ended diffusion tubes (exposed with 4 replicates); D, a new active sampling diffusion denuder system; and E, an active sampling bubbler system. Method D consisted of two 0.1 m acid coated glass denuders in series with sampling at approximately 0.3 l min-1. These methods were deployed at 6 locations in the UK and the Netherlands and compared against reference estimates. Method D was the most precise and sensitive of the techniques compared, with a detection limit of 3 micrograms m-3), but were less precise and overestimated NH3 at smaller concentrations. Of the passive methods, A was the most precise and C the least precise. On the basis of the results, method D has been implemented in the national network, together with application of method A to explore spatial variability in regions with expected high NH3 concentrations.

  7. Modelling of the diffusion of pollutants in the atmosphere under varying conditions in large cultivated regions

    International Nuclear Information System (INIS)

    Wueneke, C.D.; Schultz, H.

    1975-01-01

    The most important routines of a numerical code based on the particle-in-cell-method for calculating the transport and the turbulent dispersion of inert and radio-active pollutants in the atmosphere have been programmed and have been tested successfully on the CDC computer CYBER 73/76 of the Regional Computer Centre for Niedersachsen in Hanover. Compared to the Gaussian plume model such a numerical code based on the particle-in-cell-method offers several advantages for the computation of the diffusion under varying conditions in large cultivated regions. (orig.) [de

  8. Sustained diffusive alternating current gliding arc discharge in atmospheric pressure air

    DEFF Research Database (Denmark)

    Zhu, Jiajian; Gao, Jinlong; Li, Zhongshan

    2014-01-01

    Rapid transition from glow discharge to thermal arc has been a common problem in generating stable high-power non-thermal plasmas especially at ambient conditions. A sustained diffusive gliding arc discharge was generated in a large volume in atmospheric pressure air, driven by an alternating...... current (AC) power source. The plasma column extended beyond the water-cooled stainless steel electrodes and was stabilized by matching the flow speed of the turbulent air jet with the rated output power. Comprehensive investigations were performed using high-speed movies measured over the plasma column...

  9. Turbulent jet diffusion flame length evolution with cross flows in a sub-pressure atmosphere

    International Nuclear Information System (INIS)

    Wang, Qiang; Hu, Longhua; Zhang, Xiaozheng; Zhang, Xiaolei; Lu, Shouxiang; Ding, Hang

    2015-01-01

    Highlights: • Quantifying turbulent jet diffusion flame length with cross flows. • Unique data revealed for a sub-atmospheric pressure. • Non-dimensional global correlation proposed for flame trajectory-line length. - Abstract: This paper investigates the evolution characteristics of turbulent jet diffusion flame (flame trajectory-line length, flame height in vertical jet direction) with increasing cross flows in a sub-pressure (64 kPa) atmosphere. The combined effect of cross flow and a special sub-pressure atmosphere condition is revealed, where no data is available in the literatures. Experiments are carried out with a wind tunnel built specially in Lhasa city (altitude: 3650 m; pressure: 64 kPa) and in Hefei city (altitude: 50 m; pressure: 100 kPa), using nozzles with diameter of 3 mm, 4 mm and 5 mm and propane as fuel. It is found that, as cross flow air speed increases from zero, the flame trajectory-line length firstly decreases and then becomes almost stable (for relative small nozzle, 3 mm in this study) or increases (for relative large nozzle, 4 mm and 5 mm in this study) beyond a transitional critical cross flow air speed in normal pressure, however decreases monotonically until being blown-out in the sub-pressure atmosphere. The flame height in jet direction decreases monotonically with cross air flow speed and then reaches a steady value in both pressures. For the transitional state of flame trajectory-line length with increasing cross air flow speed, the corresponding critical cross flow air speed is found to be proportional to the fuel jet velocity, meanwhile independent of nozzle diameter. Correlation models are proposed for the flame height in jet direction and the flame trajectory-line length for both ambient pressures, which are shown to be in good agreement with the experimental results.

  10. Source term identification in atmospheric modelling via sparse optimization

    Science.gov (United States)

    Adam, Lukas; Branda, Martin; Hamburger, Thomas

    2015-04-01

    Inverse modelling plays an important role in identifying the amount of harmful substances released into atmosphere during major incidents such as power plant accidents or volcano eruptions. Another possible application of inverse modelling lies in the monitoring the CO2 emission limits where only observations at certain places are available and the task is to estimate the total releases at given locations. This gives rise to minimizing the discrepancy between the observations and the model predictions. There are two standard ways of solving such problems. In the first one, this discrepancy is regularized by adding additional terms. Such terms may include Tikhonov regularization, distance from a priori information or a smoothing term. The resulting, usually quadratic, problem is then solved via standard optimization solvers. The second approach assumes that the error term has a (normal) distribution and makes use of Bayesian modelling to identify the source term. Instead of following the above-mentioned approaches, we utilize techniques from the field of compressive sensing. Such techniques look for a sparsest solution (solution with the smallest number of nonzeros) of a linear system, where a maximal allowed error term may be added to this system. Even though this field is a developed one with many possible solution techniques, most of them do not consider even the simplest constraints which are naturally present in atmospheric modelling. One of such examples is the nonnegativity of release amounts. We believe that the concept of a sparse solution is natural in both problems of identification of the source location and of the time process of the source release. In the first case, it is usually assumed that there are only few release points and the task is to find them. In the second case, the time window is usually much longer than the duration of the actual release. In both cases, the optimal solution should contain a large amount of zeros, giving rise to the

  11. Study on fitness functions of genetic algorithm for dynamically correcting nuclide atmospheric diffusion model

    International Nuclear Information System (INIS)

    Ji Zhilong; Ma Yuanwei; Wang Dezhong

    2014-01-01

    Background: In radioactive nuclides atmospheric diffusion models, the empirical dispersion coefficients were deduced under certain experiment conditions, whose difference with nuclear accident conditions is a source of deviation. A better estimation of the radioactive nuclide's actual dispersion process could be done by correcting dispersion coefficients with observation data, and Genetic Algorithm (GA) is an appropriate method for this correction procedure. Purpose: This study is to analyze the fitness functions' influence on the correction procedure and the forecast ability of diffusion model. Methods: GA, coupled with Lagrange dispersion model, was used in a numerical simulation to compare 4 fitness functions' impact on the correction result. Results: In the numerical simulation, the fitness function with observation deviation taken into consideration stands out when significant deviation exists in the observed data. After performing the correction procedure on the Kincaid experiment data, a significant boost was observed in the diffusion model's forecast ability. Conclusion: As the result shows, in order to improve dispersion models' forecast ability using GA, observation data should be given different weight in the fitness function corresponding to their error. (authors)

  12. Numerical model for atmospheric diffusion analysis and evaluation of effective dose for safety analysis

    International Nuclear Information System (INIS)

    Sada, Koichi; Michioka, Takenobu; Ichikawa, Yoichi; Komiyama, Sumito

    2009-01-01

    A numerical simulation method has been developed to predict atmospheric flow and stack gas diffusion, considering the buildings and complex terrain located near and relatively far from a stack, respectively. The turbulence closure technique was used for flow calculation, some calculation grids on the ground near a stack were treated as buildings, and stack gas diffusion was predicted using the Lagrangian particle model. The calculated flow and stack gas diffusion results were compared with those obtained by wind tunnel experiments under actual terrain containing buildings. Effective stack height was estimated by comparing the surface concentration along the plume axis with those under a flat-plate condition, and it was apparent that the effective stack heights estimated by calculations were almost the same as those obtained by the wind tunnel experiment. Then, the effective dose and relative concentration of stack gas were calculated using the effective stack heights obtained by a numerical model. Almost the same effective dose and relative concentration were obtained when compared with those using the effective stack height obtained by wind tunnel experiment. (author)

  13. Use of radon-222 as a tracer in the study of atmospheric diffusion

    International Nuclear Information System (INIS)

    Ikebe, Y.; Yamada, H.; Nishimura, T.; Kojima, S.; Shimo, M.; Yamanishi, H.; Tojyo, K.; Iida, T.; Chino, M.

    1991-01-01

    222 Rn is one of the most useful tracer for studying the atmospheric diffusion. In this report, first we report analytical treatments about temporal variation of Rn concentration in the atmosphere to clarify origin and transport of Rn. Secondly we report the numerical simulation of the behavior of Rn. The results is compared with the observed Rn concentration for confirming the validity of the simulation. Based on the results of numerical analysis of a diffusion equation, we assumed that Rn concentration measured at Nagoya can be divided into the following two components: (I) Rn atom originated near from the measuring site, which is denoted by 'diurnal variation component'. For this, it was shown that the measured temporal variation can be explained by using ordinary non-steady state one dimensional diffusion equation. (II) Rn atoms originated far from the measuring site (including Chinese Continent), which is denoted by 'background component'. For this component, we propose a one layer transport model using air mass trajectory technique. By this model we can explain well the temporal variation of back-ground component and seasonal variation of Rn at Nagoya. A numerical simulation of the temporal variation of Rn was carried out for meso-regional scale (200kmx200kmx1km). The results was compared with the continuous measurements of Rn concentration at Nagoya, and fairly good agreements was obtained. We have obtained horizontal distributions of Rn around Nagoya (150kmx150km) for each season by using a passive method. The linear relationship between Rn concentration and measured Rn exhalation rate supports the transport model mentioned above and gives us other interesting informations. (author)

  14. Diffusion

    International Nuclear Information System (INIS)

    Kubaschewski, O.

    1983-01-01

    The diffusion rate values of titanium, its compounds and alloys are summarized and tabulated. The individual chemical diffusion coefficients and self-diffusion coefficients of certain isotopes are given. Experimental methods are listed which were used for the determination of diffusion coefficients. Some values have been taken over from other studies. Also given are graphs showing the temperature dependences of diffusion and changes in the diffusion coefficient with concentration changes

  15. GPU-based parallel computing in real-time modeling of atmospheric transport and diffusion of radioactive material

    International Nuclear Information System (INIS)

    Santos, Marcelo C. dos; Pereira, Claudio M.N.A.; Schirru, Roberto; Pinheiro, André; Coordenacao de Pos-Graduacao e Pesquisa de Engenharia

    2017-01-01

    Atmospheric radionuclide dispersion systems (ARDS) are essential mechanisms to predict the consequences of unexpected radioactive releases from nuclear power plants. Considering, that during an eventuality of an accident with a radioactive material release, an accurate forecast is vital to guide the evacuation plan of the possible affected areas. However, in order to predict the dispersion of the radioactive material and its impact on the environment, the model must process information about source term (radioactive materials released, activities and location), weather condition (wind, humidity and precipitation) and geographical characteristics (topography). Furthermore, ARDS is basically composed of 4 main modules: Source Term, Wind Field, Plume Dispersion and Doses Calculations. The Wind Field and Plume Dispersion modules are the ones that require a high computational performance to achieve accurate results within an acceptable time. Taking this into account, this work focuses on the development of a GPU-based parallel Plume Dispersion module, focusing on the radionuclide transport and diffusion calculations, which use a given wind field and a released source term as parameters. The program is being developed using the C ++ programming language, allied with CUDA libraries. In comparative case study between a parallel and sequential version of the slower function of the Plume Dispersion module, a speedup of 11.63 times could be observed. (author)

  16. GPU-based parallel computing in real-time modeling of atmospheric transport and diffusion of radioactive material

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Marcelo C. dos; Pereira, Claudio M.N.A.; Schirru, Roberto; Pinheiro, André, E-mail: jovitamarcelo@gmail.com, E-mail: cmnap@ien.gov.br, E-mail: schirru@lmp.ufrj.br, E-mail: apinheiro99@gmail.com [Instituto de Engenharia Nuclear (IEN/CNEN-RJ), Rio de Janeiro, RJ (Brazil); Coordenacao de Pos-Graduacao e Pesquisa de Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Engenharia Nuclear

    2017-07-01

    Atmospheric radionuclide dispersion systems (ARDS) are essential mechanisms to predict the consequences of unexpected radioactive releases from nuclear power plants. Considering, that during an eventuality of an accident with a radioactive material release, an accurate forecast is vital to guide the evacuation plan of the possible affected areas. However, in order to predict the dispersion of the radioactive material and its impact on the environment, the model must process information about source term (radioactive materials released, activities and location), weather condition (wind, humidity and precipitation) and geographical characteristics (topography). Furthermore, ARDS is basically composed of 4 main modules: Source Term, Wind Field, Plume Dispersion and Doses Calculations. The Wind Field and Plume Dispersion modules are the ones that require a high computational performance to achieve accurate results within an acceptable time. Taking this into account, this work focuses on the development of a GPU-based parallel Plume Dispersion module, focusing on the radionuclide transport and diffusion calculations, which use a given wind field and a released source term as parameters. The program is being developed using the C ++ programming language, allied with CUDA libraries. In comparative case study between a parallel and sequential version of the slower function of the Plume Dispersion module, a speedup of 11.63 times could be observed. (author)

  17. Development of computer-based function to estimate radioactive source term by coupling atmospheric model with monitoring data

    International Nuclear Information System (INIS)

    Akiko, Furuno; Hideyuki, Kitabata

    2003-01-01

    atmospheric dynamic equations. Meteorological fields are initialized by using numerical forecasts and/or analysis data from Japan Meteorological Agency. The horizontal and temporal resolutions of the data are 1.25 degree and 6 hours, respectively, and the data have 17 vertical layers. GEARN is a particle random walk model to calculate the atmospheric dispersion of radionuclides by tracing the trajectories of a large number of marker particles discharged from a source. Movement of marker particles in each time step is described by three basic processes: transport by three-dimensional mean winds, turbulence diffusion and deposition. Mean wind fields are provided from MM5 at the interval of 1 hour. The horizontal random movement by diffusion per time step δt is calculated as (6K hor δt) 0.5 * R, where R is a uniform random number between -1 and 1. The horizontal diffusion coefficient K hor is derived from the standard deviation of horizontal diffusion σ hor and the vertical diffusion coefficient is from MM5. The air concentration at each Eulerian grid cell is computed by summing up the number of marker particles in the grid cell. Atmospheric transport simulations are carried out for the matrix of possible release points in Eastern Asia and possible release times. Because the simulations for the matrix need much computation time, it is carried out by using parallel computer. The simulation results of air dose rates are compared with monitoring data by statistical analysis of normalized mean square error, and the best fitted release condition is chosen as source term. fig. 1 (author)

  18. Sustained diffusive alternating current gliding arc discharge in atmospheric pressure air

    Science.gov (United States)

    Zhu, Jiajian; Gao, Jinlong; Li, Zhongshan; Ehn, Andreas; Aldén, Marcus; Larsson, Anders; Kusano, Yukihiro

    2014-12-01

    Rapid transition from glow discharge to thermal arc has been a common problem in generating stable high-power non-thermal plasmas especially at ambient conditions. A sustained diffusive gliding arc discharge was generated in a large volume in atmospheric pressure air, driven by an alternating current (AC) power source. The plasma column extended beyond the water-cooled stainless steel electrodes and was stabilized by matching the flow speed of the turbulent air jet with the rated output power. Comprehensive investigations were performed using high-speed movies measured over the plasma column, synchronized with simultaneously recorded current and voltage waveforms. Dynamic details of the novel non-equilibrium discharge are revealed, which is characterized by a sinusoidal current waveform with amplitude stabilized at around 200 mA intermediate between thermal arc and glow discharge, shedding light to the governing mechanism of the sustained spark-suppressed AC gliding arc discharge.

  19. Plasma surface treatment of Cu by nanosecond-pulse diffuse discharges in atmospheric air

    Science.gov (United States)

    Cheng, ZHANG; Jintao, QIU; Fei, KONG; Xingmin, HOU; Zhi, FANG; Yu, YIN; Tao, SHAO

    2018-01-01

    Nanosecond-pulse diffuse discharges could provide high-density plasma and high-energy electrons at atmospheric pressure. In this paper, the surface treatment of Cu by nanosecond-pulse diffuse discharges is conducted in atmospheric air. Factors influencing the water contact angle (WCA), chemical composition and microhardness, such as the gap spacing and treatment time, are investigated. The results show that after the plasma surface treatment, the WCA considerably decreases from 87° to 42.3°, and the surface energy increases from 20.46 mJ m-2 to 66.28 mJ m-2. Results of energy dispersive x-ray analysis show that the concentration of carbon decreases, but the concentrations of oxygen and nitrogen increase significantly. Moreover, the microhardness increases by approximately 30% after the plasma treatment. The aforementioned changes on the Cu surface indicate the plasma surface treatment enhances the hydrophilicity and microhardness, and it cleans the carbon and achieves oxidization on the Cu surface. Furthermore, by increasing the gap spacing and treatment time, better treatment effects can be obtained. The microhardness in the case of a 2.5 cm gap is higher than that in the case of a 3 cm gap. More oxygen and nitrogen species appear on the Cu surface for the 2.5 cm gap treatment than for the 3 cm gap treatment. The WCA significantly decreases with the treatment time when it is no longer than 90 s, and then it reaches saturation. In addition, more oxygen-containing and nitrogen-containing groups appear after extended plasma treatment time. They contribute to the improvement of the hydrophilicity and oxidation on the Cu surface.

  20. Atmospheric carbon dioxide removal: long-term consequences and commitment

    International Nuclear Information System (INIS)

    Cao Long; Caldeira, Ken

    2010-01-01

    Carbon capture from ambient air has been proposed as a mitigation strategy to counteract anthropogenic climate change. We use an Earth system model to investigate the response of the coupled climate-carbon system to an instantaneous removal of all anthropogenic CO 2 from the atmosphere. In our extreme and idealized simulations, anthropogenic CO 2 emissions are halted and all anthropogenic CO 2 is removed from the atmosphere at year 2050 under the IPCC A2 CO 2 emission scenario when the model-simulated atmospheric CO 2 reaches 511 ppm and surface temperature reaches 1.8 deg. C above the pre-industrial level. In our simulations a one-time removal of all anthropogenic CO 2 in the atmosphere reduces surface air temperature by 0.8 deg. C within a few years, but 1 deg. C surface warming above pre-industrial levels lasts for several centuries. In other words, a one-time removal of 100% excess CO 2 from the atmosphere offsets less than 50% of the warming experienced at the time of removal. To maintain atmospheric CO 2 and temperature at low levels, not only does anthropogenic CO 2 in the atmosphere need to be removed, but anthropogenic CO 2 stored in the ocean and land needs to be removed as well when it outgasses to the atmosphere. In our simulation to maintain atmospheric CO 2 concentrations at pre-industrial levels for centuries, an additional amount of CO 2 equal to the original CO 2 captured would need to be removed over the subsequent 80 years.

  1. First atmospheric diffusion experiment compaign at the Angra site. Analysis of the data measured

    International Nuclear Information System (INIS)

    Nicolli, D.

    1986-07-01

    An analysis of the data measured during the first atmospheric diffusion experiment campaign at the Angra site is presented. Some time before the diffusion experiments, with tritiated water vapor used as a tracer (HTO) could be started, many preparatory studies had to be concluded due to the local complex terrain surrounded by steep hills on three sides and a bay in the southern direction. An introductory account of these previous steps is given. Tritiated water vapor was released from a 100m-high tower and air humidity sampled at 25 locations as far as 1Km downwind of the source. An elaborated isoconcentration analysis indicates the plume spread has a Gaussian distribution in the horizontal plane up to the edge of the site's area bordered by the hill's top (about 1Km far-off). Nevertheless the Gaussian model has a restricted applicability at some parts of the site because of the terrain unevenness. In general, the results are comparable to those obtained in other countries for complex terrain. Meanwhile, the Angra's experiments seem only to validate the Gaussian model for short range dispersion from an elevated source. For releases in the lowest layer, the Gaussian model might not be valid. The isoconcentration analysis strengthens the assumption of sea breeze recirculation on the site. (Author) [pt

  2. The model of atmospheric diffusion and deposition adopted for the German reactor risk study (phase A)

    International Nuclear Information System (INIS)

    Huebschmann, W.G.; Vogt, S.

    1980-01-01

    The consequence model of the German reactor risk study comprises the release of radioactivity and thermal energy from the containment, the atmospheric diffusion, and the deposition of activity on the ground, the calculation of dose equivalents induced via the main exposure pathways, and the calculation of early and late health effects to the population, taking into account emergency actions for the protection of the public. The following exposure pathways are included in the model: external irradiation from the passing cloud and from the activity deposited on the ground, inhalation of the cloud activity and of resuspended material, and ingestion of contaminated food. Account is taken of the following effects: building wake, plume rise to thermal energy release, dynamic change of diffusion parameters, and plume depletion due to radioactive decay, dry and wet deposition. The calculations are performed for 115 weather sequences with starting times evenly distributed over one year. It is shown that such a choice of weather sequences reflects the total variety of meteorological situations, including precipitation, in a statistically adequate way. The area of the Federal Republic of Germany is divided into four meteorological site-regions, each with typical meteorological characteristics. Each power reactor site is assigned to one of the meteorological site-regions

  3. Air-tough: A fully 3-dimensional linking of atmosphere with soil using eddy diffusivity concept and V-TOUGH

    Energy Technology Data Exchange (ETDEWEB)

    Montazer, P. [Multimedia Environmental Technology, Inc., Newport Beach, CA (United States)

    1995-03-01

    In arid climates, evapotranspiration is a strongly-coupled thermodynamic process that is controlled by the interaction of the atmospheric boundary layer and the upper soil surface. Simulation of this process requires a fully-coupled thermodynamic multi-phase fluid-flow and energy-transport code. Such a code was developed in a previous investigation using V-TOUGH. The resulting efficient computer code, A-TOUGH, simulates the effect of dynamic atmospheric fluctuations on vapor movement between the soil and the atmosphere and the resulting moisture movement in the soil. However, the coupling between the atmosphere and soil employed eddy diffusivity which was only a function of time and not a function of space. In the present study the code is extended to allow spatial as well as temporal variation of eddy diffusivity.

  4. Long term atmospheric aerosol characterization in the Amazon Basin

    Science.gov (United States)

    Artaxo, Paulo; Gerab, Fábio; Yamasoe, Marcia A.

    This chapter presents a characterization of atmospheric aerosols collected in different places in the Amazon Basin. Both the biogenic aerosol emission from the forest and the particulate material which is emitted to the atmosphere due to the large scale man-made burns during the dry season were studied. The samples were collected during a three year period at three different locations in the Amazon (Cuiabá, Alta Floresta and Serra do Navio), using stacked filter units. Aerosol samples were also collected directly over fires of cerrado vegetation and tropical primary forest burns The samples were analyzed using several techniques for a number of elements. Gravimetric analyses were used to determine the total atmospheric aerosol concentration. Multivariate statistical analysis was used in order to identify and characterize the sources of the atmospheric aerosol present in the sampled regions. Cerrado burning emissions were enriched compared to forest ones, specially for Cl, K and Zn. High atmospheric aerosol concentrations were observed in large amazonian areas due to emissions from man-made burns in the period from June to September. The emissions from burns dominate the fine fraction of the atmospheric aerosol with characteristic high contents of black carbon, S and K. Aerosols emitted in biomass burning process are correlated to the increase in the aerosol optical thickness of the atmosphere during the Amazonian dry season. The Serra do Navio aerosol is characterized by biogenic emissions with strong marine influence. The presence of trace elements characteristic of soil particulate associated with this marine contribution indicates the existence of aerosol transport from Africa to South America. Similar composition characteristics were observed in the biogenic emission aerosols from Serra do Navio and Alta Floresta.

  5. NUMERICAL METHODS FOR SOLVING THE MULTI-TERM TIME-FRACTIONAL WAVE-DIFFUSION EQUATION.

    Science.gov (United States)

    Liu, F; Meerschaert, M M; McGough, R J; Zhuang, P; Liu, Q

    2013-03-01

    In this paper, the multi-term time-fractional wave-diffusion equations are considered. The multi-term time fractional derivatives are defined in the Caputo sense, whose orders belong to the intervals [0,1], [1,2), [0,2), [0,3), [2,3) and [2,4), respectively. Some computationally effective numerical methods are proposed for simulating the multi-term time-fractional wave-diffusion equations. The numerical results demonstrate the effectiveness of theoretical analysis. These methods and techniques can also be extended to other kinds of the multi-term fractional time-space models with fractional Laplacian.

  6. Modeling long-term uptake and re-volatilization of semi-volatile organic compounds (SVOCs) across the soil-atmosphere interface.

    Science.gov (United States)

    Bao, Zhongwen; Haberer, Christina; Maier, Uli; Beckingham, Barbara; Amos, Richard T; Grathwohl, Peter

    2015-12-15

    Soil-atmosphere exchange is important for the environmental fate and atmospheric transport of many semi-volatile organic compounds (SVOCs). This study focuses on modeling the vapor phase exchange of semi-volatile hydrophobic organic pollutants between soil and the atmosphere using the multicomponent reactive transport code MIN3P. MIN3P is typically applied to simulate aqueous and vapor phase transport and reaction processes in the subsurface. We extended the code to also include an atmospheric boundary layer where eddy diffusion takes place. The relevant processes and parameters affecting soil-atmosphere exchange were investigated in several 1-D model scenarios and at various time scales (from years to centuries). Phenanthrene was chosen as a model compound, but results apply for other hydrophobic organic compounds as well. Gaseous phenanthrene was assumed to be constantly supplied to the system during a pollution period and a subsequent regulation period (with a 50% decline in the emission rate). Our results indicate that long-term soil-atmosphere exchange of phenanthrene is controlled by the soil compartment - re-volatilization thus depends on soil properties. A sensitivity analysis showed that accumulation and transport in soils in the short term is dominated by diffusion, whereas in the long term groundwater recharge and biodegradation become relevant. As expected, sorption causes retardation and slows down transport and biodegradation. If atmospheric concentration is reduced (e.g. after environmental regulations), re-volatilization from soil to the atmosphere occurs only for a relatively short time period. Therefore, the model results demonstrate that soils generally are sinks for atmospheric pollutants. The atmospheric boundary layer is only relevant for time scales of less than one month. The extended MIN3P code can also be applied to simulate fluctuating concentrations in the atmosphere, for instance due to temperature changes in the topsoil. Copyright

  7. Back-exchange: a novel approach to quantifying oxygen diffusion and surface exchange in ambient atmospheres.

    Science.gov (United States)

    Cooper, Samuel J; Niania, Mathew; Hoffmann, Franca; Kilner, John A

    2017-05-17

    A novel two-step Isotopic Exchange (IE) technique has been developed to investigate the influence of oxygen containing components of ambient air (such as H 2 O and CO 2 ) on the effective surface exchange coefficient (k*) of a common mixed ionic electronic conductor material. The two step 'back-exchange' technique was used to introduce a tracer diffusion profile, which was subsequently measured using Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS). The isotopic fraction of oxygen in a dense sample as a function of distance from the surface, before and after the second exchange step, could then be used to determine the surface exchange coefficient in each atmosphere. A new analytical solution was found to the diffusion equation in a semi-infinite domain with a variable surface exchange boundary, for the special case where D* and k* are constant for all exchange steps. This solution validated the results of a numerical, Crank-Nicolson type finite-difference simulation, which was used to extract the parameters from the experimental data. When modelling electrodes, D* and k* are important input parameters, which significantly impact performance. In this study La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ (LSCF6428) was investigated and it was found that the rate of exchange was increased by around 250% in ambient air compared to high purity oxygen at the same pO 2 . The three experiments performed in this study were used to validate the back-exchange approach and show its utility.

  8. NUMERICAL METHODS FOR SOLVING THE MULTI-TERM TIME-FRACTIONAL WAVE-DIFFUSION EQUATION

    OpenAIRE

    Liu, F.; Meerschaert, M.M.; McGough, R.J.; Zhuang, P.; Liu, Q.

    2013-01-01

    In this paper, the multi-term time-fractional wave-diffusion equations are considered. The multi-term time fractional derivatives are defined in the Caputo sense, whose orders belong to the intervals [0,1], [1,2), [0,2), [0,3), [2,3) and [2,4), respectively. Some computationally effective numerical methods are proposed for simulating the multi-term time-fractional wave-diffusion equations. The numerical results demonstrate the effectiveness of theoretical analysis. These methods and technique...

  9. Short-term annealing of mixed amorphous molybdenum-silicon films by means of a conventional diffusion equipment

    International Nuclear Information System (INIS)

    Kaufmann, C.; Raschke, T.; Rockoff, A.; Temmler, D.

    1985-01-01

    A short-term annealing procedure is described of mixed amorphous Mo-Si films in a retrofitted conventional diffusion equipment. By means of a special charging jig it is possible to siliconize repeatably between 1 and 120 s in oxygen-free atmosphere. The heat-treated films transform into crystalline MoSi 2 films at temperatures of 1100 0 C and 1200 0 C, respectively, and attain resistance values which correspond to a one-hour treatment at temperatures of 900 0 C up to 1000 0 C. Therefore, the procedure could be used for the production of VLSI circuits with silicide metallization. After short-term annealing the MoSi 2 films show smaller grain sizes compared to conventionally annealed samples

  10. Surface diffuse discharge mechanism of well-aligned atmospheric pressure microplasma arrays

    International Nuclear Information System (INIS)

    Zhou Ren-Wu; Li Jiang-Wei; Chen Mao-Dong; Zhang Xian-Hui; Liu Dong-Ping; Yang Si-Ze; Zhou Ru-Sen; Zhuang Jin-Xing; Ostrikov, Kostya

    2016-01-01

    A stable and homogeneous well-aligned air microplasma device for application at atmospheric pressure is designed and its electrical and optical characteristics are investigated. Current-voltage measurements and intensified charge coupled device (ICCD) images show that the well-aligned air microplasma device is able to generate a large-area and homogeneous discharge at the applied voltages ranging from 12 kV to 14 kV, with a repetition frequency of 5 kHz, which is attributed to the diffusion effect of plasma on dielectric surface. Moreover, this well-aligned microplasma device may result in the uniform and large-area surface modification of heat-sensitive PET polymers without damage, such as optimization in hydrophobicity and biocompatibility. In the biomedical field, the utility of this well-aligned microplasma device is further testified. It proves to be very efficient for the large-area and uniform inactivation of E. coli cells with a density of 10 3 /cm 2 on LB agar plate culture medium, and inactivation efficiency can reach up to 99% for 2-min treatment. (paper)

  11. Graphic displays on PCs of gaseous diffusion models of radionuclide releases to the atmosphere

    International Nuclear Information System (INIS)

    Campo Ortega, E. del

    1993-01-01

    The well-known MESOI program has been modified and improved to adapt it to a PC/AT with VGA colour monitor. Far from losing any of its powerful characteristics to calculate the transport, diffusion, deposition and decay of gaseous radioactive effluents discharged to the atmosphere, it has been enhanced to allow graphic viewing of concentrations, wind speed and direction and puff locations in colour, all on a background map of the site. The background covers a 75 x 75 km square and has a graphic grid density of 421 x 421 pixels. This means that effluent concentration is represented approximately every 170 metres in the 'clouded-area'. Among the modifications and enhancements made, the following are of particular interest: 1. A new subroutine called NUBE has been added, which calculates the distribution of effluent concentration of activity in a grid of 421 x 421 pixels. 2. Several subroutines have been added to obtain graphic displays and printouts of the cloud, wind field and puff locations. 3. Graphic display of the geographic plane of the area surrounding the effluent release point. 4. Off-line preparation of meteorological and topographical data files necessary for program execution. (author)

  12. The Hot Horizontal-Branch Stars in NGC288 - Effects of Diffusion and Stratification on Their Atmospheric Parameters*

    Science.gov (United States)

    Moehler, S.; Dreizler, S.; LeBlanc, F.; Khalack, V.; Michaud, G.; Richer, J.; Sweigart, Allen V.; Grundahl, F.

    2014-01-01

    Context. NGC288 is a globular cluster with a well developed blue horizontal branch covering the so-called u-jump which indicates the onset of diffusion. It is therefore well suited to study the effects of diffusion in blue horizontal branch (HB) stars. Aims. We compare observed abundances to predictions from stellar evolution models calculated with diffusion and from stratified atmospheric models. We verify the effect of using stratified model spectra to derive atmospheric parameters. In addition we investigate the nature of the overluminous blue HB stars around the u-jump. Methods. We define a new photometric index sz from uvby measurements that is gravity sensitive between 8 000K and 12 000 K. Using medium-resolution spectra and Stroemgren photometry we determine atmospheric parameters (Teff, logg) and abundances for the blue HB stars. We use both homogeneous and stratified model spectra for our spectroscopic analyses. Results. The atmospheric parameters and masses of the hot HB stars in NGC288 show a behaviour seen also in other clusters for temperatures between 9 000K and 14 000 K. Outside this temperature range, however, they follow rather the results found for such stars in (omega)Cen. The abundances derived from our observations are for most elements (except He and P) within the abundance range expected from evolutionary models that include the effects of atomic diffusion and assume a surface mixed mass of 10(exp -7) M. The abundances predicted by stratified model atmospheres are generally significantly more extreme than observed, except for Mg. The use of stratified model spectra to determine effective temperatures, surface gravities and masses moves the hotter stars to a closer agreement with canonical evolutionary predictions. Conclusions. Our results show definite promise towards solving the long-standing issue of surface gravity and mass discrepancies for hot HB stars, but there is still much work needed to arrive at a self-consistent solution.

  13. Effect on the annual atmospheric dispersion factor of different diffusion parameters and meteorological data at nuclear power plant

    International Nuclear Information System (INIS)

    Hu Erbang; Yan Jiangyu; Wang Han; Xin Cuntian

    2003-01-01

    Based on the hourly metrological observing data of 100 m high tower during 1997-1999 at Tianwan Nuclear Power Plant (NPP) site and 1995-1997 in Fujian Huian NPP site, the effect on the annual atmospheric dispersion factor (AADF) of four different diffusion parameters (on-site measuring values, IAEA's, Briggs's and Pasquill's) are estimated. The analysis shows that the deviation between the results from IAEA's, Briggs's and on-site measured diffusion parameters is less than 20%. The effect on the AADF from different years' meteorological data also is estimated. (authors)

  14. Stability analysis of impulsive fuzzy cellular neural networks with distributed delays and reaction-diffusion terms

    International Nuclear Information System (INIS)

    Li Zuoan; Li Kelin

    2009-01-01

    In this paper, we investigate a class of impulsive fuzzy cellular neural networks with distributed delays and reaction-diffusion terms. By employing the delay differential inequality with impulsive initial conditions and M-matrix theory, we find some sufficient conditions ensuring the existence, uniqueness and global exponential stability of equilibrium point for impulsive fuzzy cellular neural networks with distributed delays and reaction-diffusion terms. In particular, the estimate of the exponential converging index is also provided, which depends on the system parameters. An example is given to show the effectiveness of the results obtained here.

  15. Global exponential stability of fuzzy cellular neural networks with delays and reaction-diffusion terms

    International Nuclear Information System (INIS)

    Wang Jian; Lu Junguo

    2008-01-01

    In this paper, we study the global exponential stability of fuzzy cellular neural networks with delays and reaction-diffusion terms. By constructing a suitable Lyapunov functional and utilizing some inequality techniques, we obtain a sufficient condition for the uniqueness and global exponential stability of the equilibrium solution for a class of fuzzy cellular neural networks with delays and reaction-diffusion terms. The result imposes constraint conditions on the network parameters independently of the delay parameter. The result is also easy to check and plays an important role in the design and application of globally exponentially stable fuzzy neural circuits

  16. Identifying the limitations of conventional biofiltration of diffuse methane emissions at long-term operation.

    Science.gov (United States)

    Gómez-Cuervo, S; Hernández, J; Omil, F

    2016-08-01

    There is growing international concern about the increasing levels of greenhouse gases in the atmosphere, particularly CO2 and methane. The emissions of methane derived from human activities are associated with large flows and very low concentrations, such as those emitted from landfills and wastewater treatment plants, among others. The present work was focused on the biological methane degradation at diffuse concentrations (0.2% vv(-1)) in a conventional biofilter using a mixture of compost, perlite and bark chips as carrier. An extensive characterization of the process was carried out at long-term operation (250 days) in a fully monitored pilot plant, achieving stable conditions during the entire period. Operational parameters such as waterings, nitrogen addition and inlet loads and contact time influences were evaluated. Obtained results indicate that empty bed residence times within 4-8 min are crucial to maximize elimination rates. Waterings and the type of nitrogen supplied in the nutrient solution (ammonia or nitrate) have a strong impact on the biofilter performance. The better results compatible with a stable operation were achieved using nitrate, with elimination capacities up to 7.6 ± 1.1 g CH4 m(-3 )h(-1). The operation at low inlet concentrations (IC) implied that removal rates obtained were quite limited (ranging 3-8 g CH4 m(-3 )h(-1)); however, these results could be significantly increased (up to 20.6 g CH4 m(-3) h(-1)) at higher IC, which indicates that the mass transfer from the gas to the liquid layer surrounding the biofilm is a key limitation of the process.

  17. A diffusive atmospheric pressure glow discharge in a coaxial pin-to-ring gap with a transverse magnetic field

    Directory of Open Access Journals (Sweden)

    YongSheng Wang

    2017-09-01

    Full Text Available Atmospheric pressure glow discharge (APGD has been widely used in the industrial field. The industrial applications are based on achieving stable and diffusive APGD in a relatively large space. The existing sources only achieved stable and diffusive APGD between a short inter-electrode distance within 5 millimeters. In this paper, the effect of a transverse stationary magnetic field on the diffusion of filamentary APGD was studied in a pin-to-ring coaxial gap. The APGD was driven by a high-voltage resonant power supply, and the stationary magnetic field was supplied by a permanent magnet. The stable and diffusive APGD was achieved in the circular area, which diameter was 20 millimeters. The experimental results revealed that more collision ionization occurred and the plasma was distributed diffusively in the discharge gap by applying the external transverse magnetic field. Besides, it is likely to obtain more stable and diffusive APGD in the coaxial pin-to-ring discharge gap when adjusting the input voltage, transverse magnetic flux density and resonant frequency of the power supply.

  18. Production of atmospheric pressure diffuse nanosecond pulsed dielectric barrier discharge using the array needles-plate electrode in air

    International Nuclear Information System (INIS)

    Yang Dezheng; Wang Wenchun; Jia Li; Nie Dongxia; Shi Hengchao

    2011-01-01

    In this paper, a bidirectional high pulse voltage with 20 ns rising time is employed to generate an atmospheric pressure diffuse dielectric barrier discharge using the array needles-plate electrode configuration. Both double needle and multiple needle electrode configurations nanosecond pulsed dielectric barrier discharges are investigated. It is found that a diffuse discharge plasma with low gas temperature can be obtained, and the plasma volume increases with the increase of the pulse peak voltage, but remains almost constant with the increase of the pulse repetition rate. In addition to showing the potential application on a topographically nonuniform surface treatment of the discharge, the multiple needle-plate electrode configuration with different needle-plate electrode gaps are also employed to generate diffuse discharge plasma.

  19. Global exponential stability of BAM neural networks with time-varying delays and diffusion terms

    International Nuclear Information System (INIS)

    Wan Li; Zhou Qinghua

    2007-01-01

    The stability property of bidirectional associate memory (BAM) neural networks with time-varying delays and diffusion terms are considered. By using the method of variation parameter and inequality technique, the delay-independent sufficient conditions to guarantee the uniqueness and global exponential stability of the equilibrium solution of such networks are established

  20. Global exponential stability of BAM neural networks with time-varying delays and diffusion terms

    Science.gov (United States)

    Wan, Li; Zhou, Qinghua

    2007-11-01

    The stability property of bidirectional associate memory (BAM) neural networks with time-varying delays and diffusion terms are considered. By using the method of variation parameter and inequality technique, the delay-independent sufficient conditions to guarantee the uniqueness and global exponential stability of the equilibrium solution of such networks are established.

  1. Land-atmosphere coupling and soil moisture memory contribute to long-term agricultural drought

    Science.gov (United States)

    Kumar, S.; Newman, M.; Lawrence, D. M.; Livneh, B.; Lombardozzi, D. L.

    2017-12-01

    We assessed the contribution of land-atmosphere coupling and soil moisture memory on long-term agricultural droughts in the US. We performed an ensemble of climate model simulations to study soil moisture dynamics under two atmospheric forcing scenarios: active and muted land-atmosphere coupling. Land-atmosphere coupling contributes to a 12% increase and 36% decrease in the decorrelation time scale of soil moisture anomalies in the US Great Plains and the Southwest, respectively. These differences in soil moisture memory affect the length and severity of modeled drought. Consequently, long-term droughts are 10% longer and 3% more severe in the Great Plains, and 15% shorter and 21% less severe in the Southwest. An analysis of Coupled Model Intercomparsion Project phase 5 data shows four fold uncertainty in soil moisture memory across models that strongly affects simulated long-term droughts and is potentially attributable to the differences in soil water storage capacity across models.

  2. Consequences of Windscale accident (October 1957) and study of the validity of the Sutton's mathematical model of atmospheric diffusion (1960)

    International Nuclear Information System (INIS)

    Doury, A.

    1960-01-01

    The reactor accident that happens at the number 1 pile of Windscale in 1957 was followed by a discharge of radioactive products into the atmosphere from the 1.X.1957 at 4.30 PM to the 12.X.1957 at 3.10 PM. On october the 11 th it was possible to say that there was no more risk either of external irradiation or inhalation. But in adopting a M.A.C. of 0,1 μcurie of iodine 131 per litre of milk, the Authority had to control the milk delivery till november 23 rd on a 500 km 2 area. On the other hand, this exceptional accident permit to verify that Sutton's atmospheric diffusion model could give an easy means to foresee, with a sufficient approximation, the consequences of a dispersion of radioactive products into the atmosphere. (author) [fr

  3. On Modelling Long Term Stock Returns with Ergodic Diffusion Processes: Arbitrage and Arbitrage-Free Specifications

    Directory of Open Access Journals (Sweden)

    Bernard Wong

    2009-01-01

    martingale component is based on an ergodic diffusion with a specified stationary distribution. These models are particularly useful for long horizon asset-liability management as they allow the modelling of long term stock returns with heavy tail ergodic diffusions, with tractable, time homogeneous dynamics, and which moreover admit a complete financial market, leading to unique pricing and hedging strategies. Unfortunately the standard specifications of these models in literature admit arbitrage opportunities. We investigate in detail the features of the existing model specifications which create these arbitrage opportunities and consequently construct a modification that is arbitrage free.

  4. Long-term changes and trends in the upper atmosphere - An introduction

    Czech Academy of Sciences Publication Activity Database

    Laštovička, Jan; Akmaev, R. A.; Emmert, J. T.

    2009-01-01

    Roč. 71, 14-15 (2009), s. 1511-1513 ISSN 1364-6826 Institutional research plan: CEZ:AV0Z30420517 Keywords : long-term changes * long-term trends * upper atmosphere Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 1.643, year: 2009 http://www.sciencedirect.com/science/journal/13646826

  5. Long-term trends in the ionosphere and upper atmosphere parameters

    Czech Academy of Sciences Publication Activity Database

    Bremer, J.; Alfonsi, L.; Pal, B.; Laštovička, Jan; Mikhailov, A. V.; Rogers, N.

    47 /suppl./, 2/3 (2004), s. 1009-1029 ISSN 1593-5213. [Final Meeting COST271 Action. Effects of the upper atmosphere on terrestrial and Earth-space communications (EACOS). Abingdon, 26.08.2004-27.08.2004] R&D Projects: GA MŠk OC 271.10 Institutional research plan: CEZ:AV0Z3042911 Keywords : long-term trends * ionosphere * upper atmosphere Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 0.413, year: 2004

  6. The Galerkin Finite Element Method for A Multi-term Time-Fractional Diffusion equation

    OpenAIRE

    Jin, Bangti; Lazarov, Raytcho; Liu, Yikan; Zhou, Zhi

    2014-01-01

    We consider the initial/boundary value problem for a diffusion equation involving multiple time-fractional derivatives on a bounded convex polyhedral domain. We analyze a space semidiscrete scheme based on the standard Galerkin finite element method using continuous piecewise linear functions. Nearly optimal error estimates for both cases of initial data and inhomogeneous term are derived, which cover both smooth and nonsmooth data. Further we develop a fully discrete scheme based on a finite...

  7. Decomposing Shortwave Top-of-Atmosphere Radiative Flux Variability in Terms of Surface and Atmospheric Contributions Using CERES Observations

    Science.gov (United States)

    Loeb, N. G.; Wong, T.; Wang, H.

    2017-12-01

    Earth's climate is determined by the exchange of radiant energy between the Sun, Earth and space. The absorbed solar radiation (ASR) fuels the climate system, providing the energy required for atmospheric and oceanic motions, while the system cools by emitting outgoing longwave (LW) radiation to space. A central objective of the Clouds and the Earth's Radiant Energy System (CERES) is to produce a long-term global climate data record of Earth's radiation budget along with the associated atmospheric and surface properties that influence it. CERES data products utilize a number of data sources, including broadband radiometers measuring incoming and reflected solar radiation and OLR, polar orbiting and geostationary spectral imagers, meteorological, aerosol and ozone assimilation data, and snow/sea-ice maps based on microwave radiometer data. Here we use simple diagnostic model of Earth's albedo and CERES Energy Balanced and Filled (EBAF) Ed4.0 data for March 2000-February 2016 to quantify interannual variations in SW TOA flux associated with surface albedo and atmospheric reflectance and transmittance variations. Surface albedo variations account for cloud properties over the Arctic Ocean.

  8. Influence of stability classification on atmospheric diffusion calculations for elevated releases over a terrain of major roughness

    International Nuclear Information System (INIS)

    Hu Erbang

    1988-01-01

    A series (22) of atmospheric tracer experiments with 100m release height have been performed at the kernforschungszentrum karlsruhe (KfK) of West Germany over a terrain of major roughness (Z 0 = 1.5 m). The concentration data of the tracers are statistically analysed in which 5 methods of stability classification are used. The results show that the normalized diffusion factors predicted by Gaussian plume dispersion model is in good agreement with the observed ones for elevated releases over a terrain of major roughness. Differnent sets of dispersion parameters could be obtained for the same series of atmospheric tracer experiments if different methods of classification are applied. The same method of stability classification should be used for the application of these dispersion parameters to evaluate the environment impact

  9. MODEL FOR UNSTEADY OF DIFFUSION –ADVECTION OF RADON IN SOIL – ATMOSPHERE

    Directory of Open Access Journals (Sweden)

    Parovik R.I.

    2010-04-01

    Full Text Available We consider a mathematical model for unsteady transport of radon from the constant coefficients in the soil – atmosphere. An explicit analytical solution for this model and built at different times of his profiles.

  10. Long- and short-term temporal variations of the diffuse CO2 emission from Timanfaya volcano, Lanzarote, Canary Islands

    Science.gov (United States)

    Hernández, P. A.; Padilla, G.; Calvo, D.; Padrón, E.; Melian, G.; Dionis, S.; Nolasco, D.; Barrancos, J.; Rodríguez, F.; Pérez, N.

    2012-04-01

    Lanzarote Island is an emergent part of the East Canary Ridge and it is situated approximately 100 km from the NW coast of Morocco, covering an area of about 795km2. The largest historical eruption of the Canary Islands, Timanfaya, took place during 1730-36 in this island when long-term eruptions from a NE-SW-trending fissure formed the Montañas del Fuego. The last eruption at Lanzarote Island occurred during 1824, Tinguaton volcano, and produced a much smaller lava flow that reached the SW coast. At present, one of the most prominent phenomena at Timanfaya volcanic field is the high maintained superficial temperatures occurring in the area since the 1730 volcanic eruption. The maximum temperatures recorded in this zone are 605°C, taken in a slightly inclined well 13 m deep. Since fumarolic activity is absent at the surface environment of Lanzarote, to study the diffuse CO2 emission becomes an ideal geochemical tool for monitoring its volcanic activity. Soil CO2 efflux surveys were conducted throughout Timanfaya volcanic field and surrounding areas during the summer periods of 2006, 2007, 2008, 2009, fall period of 2010 and winter, spring and summer periods of 2011 to investigate long and short-term temporal variations of the diffuse CO2 emission from Timanfaya volcano. Soil CO2 efflux surveys were undertaken at Timanfaya volcanic field always under stable weather conditions to minimize effects of meteorological conditions on the CO2 at the soil atmosphere. Approximately 370-430 sampling sites were selected at the surface environment of Timanfaya to obtain an even distribution of the sampling points over the study area. The accumulation chamber method (Parkinson et al., 1981) was used to perform soil CO2 efflux measurements in-situ by means of a portable non dispersive infrared (NDIR) CO2 analyzer, which was interfaced to a hand size computer that runs data acquisition software. At each sampling site, soil temperature at 15 and 40cm depth was also measured by

  11. Contribution of atmospheric nitrogen deposition to diffuse pollution in a typical hilly red soil catchment in southern China.

    Science.gov (United States)

    Shen, Jianlin; Liu, Jieyun; Li, Yong; Li, Yuyuan; Wang, Yi; Liu, Xuejun; Wu, Jinshui

    2014-09-01

    Atmospheric nitrogen (N) deposition is currently high and meanwhile diffuse N pollution is also serious in China. The correlation between N deposition and riverine N export and the contribution of N deposition to riverine N export were investigated in a typical hilly red soil catchment in southern China over a two-year period. N deposition was as high as 26.1 to 55.8kgN/(ha·yr) across different land uses in the studied catchment, while the riverine N exports ranged from 7.2 to 9.6kgN/(ha·yr) in the forest sub-catchment and 27.4 to 30.3kgN/(ha·yr) in the agricultural sub-catchment. The correlations between both wet N deposition and riverine N export and precipitation were highly positive, and so were the correlations between NH4(+)-N or NO3(-)-N wet deposition and riverine NH4(+)-N or NO3(-)-N exports except for NH4(+)-N in the agricultural sub-catchment, indicating that N deposition contributed to riverine N export. The monthly export coefficients of atmospheric deposited N from land to river in the forest sub-catchment (with a mean of 14%) presented a significant positive correlation with precipitation, while the monthly contributions of atmospheric deposition to riverine N export (with a mean of 18.7% in the agricultural sub-catchment and a mean of 21.0% in the whole catchment) were significantly and negatively correlated with precipitation. The relatively high contribution of N deposition to diffuse N pollution in the catchment suggests that efforts should be done to control anthropogenic reactive N emissions to the atmosphere in hilly red soil regions in southern China. Copyright © 2014. Published by Elsevier B.V.

  12. Numerical modeling of turbulent jet diffusion flames in the atmospheric surface layer

    NARCIS (Netherlands)

    Hernández, J.; Crespo, A.; Duijm, N.J.

    1995-01-01

    The evolution of turbulent jet diffusion flames of natural gas in air is predicted using a finite-volume procedure for solving the flow equations. The model is three dimensional, elliptic and based on the conserved-scalar approach and the laminar flamelet concept. A laminar flamelet prescription for

  13. Choosing the best meteorological conditions for atmospheric diffusion experiments at the Angra site

    International Nuclear Information System (INIS)

    Nicolli, D.; Thomas, P.

    1983-01-01

    The most appropriate meteorological conditions and time of the day advisable for carrying out diffusion experiments at the Angra site are described. Two emission points were defined, and the sampling area was determined with easy access to the complex terrain taken into consideration. The onsite meteorological measuring system is briefly described. (Author) [pt

  14. Diffusive transport and evaporation to the atmosphere from a NAPL source in the vadose zone

    DEFF Research Database (Denmark)

    Holtegaard, L.E.; Bjerre, T.; Christophersen, Mette

    2002-01-01

    To evaluate the risks concerned with the presence of volatile organic compounds in the unsaturated zone it is important to know how the compounds are transported in the soil. In this project the effective diffusion coefficient of 3-methylpentane, hexane, methyl-cyclopentane, iso-octane and methyl...

  15. Long-term leaf production response to elevated atmospheric carbon dioxide and tropospheric ozone

    Science.gov (United States)

    Alan F. Talhelm; Kurt S. Pregitzer; Christian P. Giardina

    2011-01-01

    Elevated concentrations of atmospheric CO2 and tropospheric O3 will profoundly influence future forest productivity, but our understanding of these influences over the long-term is poor. Leaves are key indicators of productivity and we measured the mass, area, and nitrogen concentration of leaves collected in litter traps...

  16. Soil atmosphere exchange of carbonyl sulfide (COS regulated by diffusivity depending on water-filled pore space

    Directory of Open Access Journals (Sweden)

    H. Van Diest

    2008-04-01

    Full Text Available The exchange of carbonyl sulfide (COS between soil and the atmosphere was investigated for three arable soils from Germany, China and Finland and one forest soil from Siberia for parameterization in the relation to ambient carbonyl sulfide (COS concentration, soil water content (WC and air temperature. All investigated soils acted as sinks for COS. A clear and distinct uptake optimum was found for the German, Chinese, Finnish and Siberian soils at 11.5%, 9%, 11.5%, and 9% soil WC, respectively, indicating that the soil WC acts as an important biological and physical parameter for characterizing the exchange of COS between soils and the atmosphere. Different optima of deposition velocities (Vd as observed for the Chinese, Finnish and Siberian boreal soil types in relation to their soil WC, aligned at 19% in relation to the water-filled pore space (WFPS, indicating the dominating role of gas diffusion. This interpretation was supported by the linear correlation between Vd and bulk density. We suggest that the uptake of COS depends on the diffusivity dominated by WFPS, a parameter depending on soil WC, soil structure and porosity of the soil.

  17. Some discussions on micrometeorology and atmospheric diffusion of classic and radioactive industrial pollutions. 3

    International Nuclear Information System (INIS)

    Veverka, O.; Valenta, V.; Vlachovsky, K.

    1977-01-01

    The vertical motion of an industrial plume, either conventional or radioactive is discussed and the respective formulas are given. The solution is given for the vertical rise of the plume and for the bent-over semi-horizontal plume under neutral, stable, and unstable atmospheric conditions. A theoretical model is described for the continuous rise of the radioactive plume under stable atmospheric conditions. The effective height is defined of the plume with regard to the shape of terrain and wind velocity. (J.P.)

  18. Some discussions on micrometeorology and atmospheric diffusion of classic and radioactive industrial pollutions. 1

    International Nuclear Information System (INIS)

    Veverka, O.; Vlachovsky, K.; Valenta, V.

    1976-01-01

    The fundamental static equations are given describing the atmosphere. Relations are derived for the description of dynamic phenomena, such as changes in temperature, pressure and density of the air in the lower part of the atmosphere. The effect of wind is considered and the expressions are presented for the vertical profile of wind velocity. The properties of flow are discussed in the fully developed boundary layer, such as stress, viscous stress and dynamic viscosity. The concept of surface roughness and its significance for micrometeorology is dealt with. (L.O.)

  19. Some discussions on micrometeorology and atmospheric diffusion of classic and radioactive industrial pollutions. 5

    International Nuclear Information System (INIS)

    Veverka, O.; Valenta, V.; Vlachovsky, K.

    1976-01-01

    The formulae are given expressing the atmospheric dispersion of industrial emissions released from the stacks of industrial plants and power plants. Gaussian distribution of the emissions is assumed. The behaviour of the plume is discussed and the concepts of lofting and fumigation are explained. Generalized relations are derived for the calculation of the atmospheric dispersion of gaseous wastes applicable to both high and short stack disposal and to the leakage from buildings, assuming that the source of emissions is of a point type and emissions are released continuously. (L.O.)

  20. Validation of ammonia diffusive and active samplers in a controlled atmosphere test facility using traceable Primary Standard Gas Mixtures

    Science.gov (United States)

    Martin, Nicholas A.; Ferracci, Valerio; Cassidy, Nathan; Hook, Josh; Battersby, Ross M.; Tang, Yuk S.; Stevens, Amy C. M.; Jones, Matthew R.; Braban, Christine F.; Gates, Linda; Hangartner, Markus; Stoll, Jean-Marc; Sacco, Paolo; Pagani, Diego; Hoffnagle, John A.

    2017-04-01

    Intensive animal farming, the increased use of fertilizers, and certain industrial processes are believed to be responsible for the observed increases in the amount fraction of ammonia (NH3) found in Europe. NH3 contributes to eutrophication and acidification of land and freshwater, potentially leading to a loss of biodiversity and undesirable changes to the ecosystem. It also contributes to the formation of secondary particulate matter (PM) formation, which is associated with poor air quality and adverse health outcomes. Measurements of ambient ammonia are principally carried out with low-cost diffusive samplers or by active sampling with denuders, with each method delivering time-integrated values over the monitoring period. However, such techniques have not yet been extensively validated. The goal of this work was to provide improvements in the metrological traceability through the determination of NH3 diffusive sampling rates. Five different designs of commercial diffusive samplers (FSM Radiello radial sampler, Gradko diffusion tube, Gradko DIFRAM-400, Passam ammonia sampler, and CEH ALPHA sampler) were employed, together with a pumped denuder sampler (CEH DELTA denuder) for comparison. All devices were simultaneously exposed for either 28 days or 14 days (dependent on sampler type) in a controlled atmosphere test facility (CATFAC) containing traceable amount fractions of humidified ammonia using new stable ammonia Primary Standard Gas Mixtures developed by gravimetry at NPL, under a wide range of conditions that are relevant to ambient monitoring. Online continuous monitoring of the ammonia test atmospheres was carried out by extractive sampling, employing a calibrated cavity ring-down spectrometer, which had been modified to account for cross interference by water vapour. Each manufacturer extracted the captured ammonia on the exposed samplers in the form of ammonium (NH4+) using their own accredited traceable wet chemical techniques, and then reported data

  1. Constraining Marsh Carbon Budgets Using Long-Term C Burial and Contemporary Atmospheric CO2 Fluxes

    Science.gov (United States)

    Forbrich, I.; Giblin, A. E.; Hopkinson, C. S.

    2018-03-01

    Salt marshes are sinks for atmospheric carbon dioxide that respond to environmental changes related to sea level rise and climate. Here we assess how climatic variations affect marsh-atmosphere exchange of carbon dioxide in the short term and compare it to long-term burial rates based on radiometric dating. The 5 years of atmospheric measurements show a strong interannual variation in atmospheric carbon exchange, varying from -104 to -233 g C m-2 a-1 with a mean of -179 ± 32 g C m-2 a-1. Variation in these annual sums was best explained by differences in rainfall early in the growing season. In the two years with below average rainfall in June, both net uptake and Normalized Difference Vegetation Index were less than in the other three years. Measurements in 2016 and 2017 suggest that the mechanism behind this variability may be rainfall decreasing soil salinity which has been shown to strongly control productivity. The net ecosystem carbon balance was determined as burial rate from four sediment cores using radiometric dating and was lower than the net uptake measured by eddy covariance (mean: 110 ± 13 g C m-2 a-1). The difference between these estimates was significant and may be because the atmospheric measurements do not capture lateral carbon fluxes due to tidal exchange. Overall, it was smaller than values reported in the literature for lateral fluxes and highlights the importance of investigating lateral C fluxes in future studies.

  2. Diffusion near buildings as determined from atmospheric tracer experiments. Technical report

    Energy Technology Data Exchange (ETDEWEB)

    Sagendorf, J.F.; Ricks, N.R.; Start, G.E.; Dickson, C.R.

    1980-09-01

    Data from the innermost arcs and roof top samplers of the Rancho Seco and EOCR field studies were used to examine diffusion close to a building. The minimum length plume paths were determined from each release location to each sampler position at these two test sites. Measured concentrations, normalized by source strength (C/Q), were plotted versus plume path length and an envelope containing 95% of the measured values of C/Q was determined. The curves from the two sites were similar in shape and implied three zones of diffusion. Comparisons were also made with current NRC methods for predicting maximum expected concentrations close to a building. The NRC model overestimated concentrations in all but one case. The model was generally within an order of magnitude at EOCR, and within two orders of magnitude at Rancho Seco.

  3. Some discussions on micrometeorology and atmospheric diffusion of classic and radioactive industrial sollutions. 7

    International Nuclear Information System (INIS)

    Veverka, O.; Vlachovsky, K.; Valenta, V.

    1976-01-01

    The effects are shown of small horizontal wind fluctuations on the dispersion parameters, which will acquire higher values. This will cause more intense diffusion in the horizontal direction perpendicular to the main wind direction. Thus the plume will get more spread in lower concentrations. Some measurement methods of the dispersion parameters take this influence into consideration during the experimental stage - in these cases the data need not be corrected. (author)

  4. Some discussions on micrometeorology and atmospheric diffusion of classic and radioactive industrial pollutions. 4

    International Nuclear Information System (INIS)

    Veverka, O.; Vlachovsky, K.; Valenta, V.

    1977-01-01

    The mean horizontal wind velocity is defined and it is calculated that it varies little with height so that it may be considered as constant up to the reference level which corresponds to the height of the source of industrial pollution. The formula is given for the calculation of the mean dispersion values of the diffusion coefficient and of the dispersion factor. (J.P.)

  5. Exploring the dynamics of balance data - movement variability in terms of drift and diffusion

    Energy Technology Data Exchange (ETDEWEB)

    Gottschall, Julia [Institute of Physics, University of Oldenburg, D-26111 Oldenburg (Germany)], E-mail: julia.gottschall@uni-oldenburg.de; Peinke, Joachim [Institute of Physics, University of Oldenburg, D-26111 Oldenburg (Germany)], E-mail: peinke@uni-oldenburg.de; Lippens, Volker [Department of Human Movement, University of Hamburg, Moller Street 10, D-20148 Hamburg (Germany)], E-mail: vlippens@uni-hamburg.de; Nagel, Volker [Department of Human Movement, University of Hamburg, Moller Street 10, D-20148 Hamburg (Germany)

    2009-02-23

    We introduce a method to analyze postural control on a balance board by reconstructing the underlying dynamics in terms of a Langevin model. Drift and diffusion coefficients are directly estimated from the data and fitted by a suitable parametrization. The governing parameters are utilized to evaluate balance performance and the impact of supra-postural tasks on it. We show that the proposed method of analysis gives not only self-consistent results but also provides a plausible model for the reconstruction of balance dynamics.

  6. Exploring the dynamics of balance data - movement variability in terms of drift and diffusion

    International Nuclear Information System (INIS)

    Gottschall, Julia; Peinke, Joachim; Lippens, Volker; Nagel, Volker

    2009-01-01

    We introduce a method to analyze postural control on a balance board by reconstructing the underlying dynamics in terms of a Langevin model. Drift and diffusion coefficients are directly estimated from the data and fitted by a suitable parametrization. The governing parameters are utilized to evaluate balance performance and the impact of supra-postural tasks on it. We show that the proposed method of analysis gives not only self-consistent results but also provides a plausible model for the reconstruction of balance dynamics

  7. The Galerkin finite element method for a multi-term time-fractional diffusion equation

    KAUST Repository

    Jin, Bangti

    2015-01-01

    © 2014 The Authors. We consider the initial/boundary value problem for a diffusion equation involving multiple time-fractional derivatives on a bounded convex polyhedral domain. We analyze a space semidiscrete scheme based on the standard Galerkin finite element method using continuous piecewise linear functions. Nearly optimal error estimates for both cases of initial data and inhomogeneous term are derived, which cover both smooth and nonsmooth data. Further we develop a fully discrete scheme based on a finite difference discretization of the time-fractional derivatives, and discuss its stability and error estimate. Extensive numerical experiments for one- and two-dimensional problems confirm the theoretical convergence rates.

  8. Adaptive exponential synchronization of delayed neural networks with reaction-diffusion terms

    International Nuclear Information System (INIS)

    Sheng Li; Yang Huizhong; Lou Xuyang

    2009-01-01

    This paper presents an exponential synchronization scheme for a class of neural networks with time-varying and distributed delays and reaction-diffusion terms. An adaptive synchronization controller is derived to achieve the exponential synchronization of the drive-response structure of neural networks by using the Lyapunov stability theory. At the same time, the update laws of parameters are proposed to guarantee the synchronization of delayed neural networks with all parameters unknown. It is shown that the approaches developed here extend and improve the ideas presented in recent literatures.

  9. Gas Diffusion Barriers Prepared by Spatial Atmospheric Pressure Plasma Enhanced ALD.

    Science.gov (United States)

    Hoffmann, Lukas; Theirich, Detlef; Pack, Sven; Kocak, Firat; Schlamm, Daniel; Hasselmann, Tim; Fahl, Henry; Räupke, André; Gargouri, Hassan; Riedl, Thomas

    2017-02-01

    In this work, we report on aluminum oxide (Al 2 O 3 ) gas permeation barriers prepared by spatial ALD (SALD) at atmospheric pressure. We compare the growth characteristics and layer properties using trimethylaluminum (TMA) in combination with an Ar/O 2 remote atmospheric pressure plasma for different substrate velocities and different temperatures. The resulting Al 2 O 3 films show ultralow water vapor transmission rates (WVTR) on the order of 10 -6 gm -2 d -1 . In notable contrast, plasma based layers already show good barrier properties at low deposition temperatures (75 °C), while water based processes require a growth temperature above 100 °C to achieve equally low WVTRs. The activation energy for the water permeation mechanism was determined to be 62 kJ/mol.

  10. A Universal Transition in Atmospheric Diffusion for Hot Subdwarfs Near 18,000 K

    Science.gov (United States)

    Brown, T. M.; Taylor, J. M.; Cassisi, S.; Sweigart, A. V.; Bellini, A.; Bedin, L. R.; Salaris, M.; Renzini, A.; Dalessandro, E.

    2017-12-01

    In the color–magnitude diagrams of globular clusters, when the locus of stars on the horizontal branch extends to hot temperatures, discontinuities are observed at colors corresponding to ∼12,000 and ∼18,000 K. The former is the “Grundahl jump” that is associated with the onset of radiative levitation in the atmospheres of hot subdwarfs. The latter is the “Momany jump” that has remained unexplained. Using the Space Telescope Imaging Spectrograph on the Hubble Space Telescope, we have obtained ultraviolet and blue spectroscopy of six hot subdwarfs straddling the Momany jump in the massive globular cluster ω Cen. By comparison to model atmospheres and synthetic spectra, we find that the feature is due primarily to a decrease in atmospheric Fe for stars hotter than the feature, amplified by the temperature dependence of the Fe absorption at these effective temperatures. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with program GO-14759.

  11. Strong Maximum Principle for Multi-Term Time-Fractional Diffusion Equations and its Application to an Inverse Source Problem

    OpenAIRE

    Liu, Yikan

    2015-01-01

    In this paper, we establish a strong maximum principle for fractional diffusion equations with multiple Caputo derivatives in time, and investigate a related inverse problem of practical importance. Exploiting the solution properties and the involved multinomial Mittag-Leffler functions, we improve the weak maximum principle for the multi-term time-fractional diffusion equation to a stronger one, which is parallel to that for its single-term counterpart as expected. As a direct application, w...

  12. Atmospheric response in aurora experiment: Observations of E and F region neutral winds in a region of postmidnight diffuse aurora

    International Nuclear Information System (INIS)

    Larsen, M.F.; Marshall, T.R.; Mikkelsen, I.S.

    1995-01-01

    The goal of the Atmospheric Response in Aurora (ARIA) experiment carried out at Poker Flat, Alaska, on March 3, 1992, was to determine the response of the neutral atmosphere to the long-lived, large-scale forcing that is characteristic of the diffuse aurora in the postmidnight sector. A combination of chemical release rocket wind measurements, intrumented rocket composition measurements, and ground-based optical measurements were used to characterize the response of the neutral atmosphere. The rocket measurements were made at the end of a 90-min period of strong Joule heating. We focus on the neutral wind measurements made with the rocket. The forcing was determined by running the assimilated mapping of ionospheric electrodynamics (AMIE) analysis procedure developed at the National Center for Atmospheric Research. The winds expected at the latitude and longitude of the experiment were calculated using the spectral thermospheric general circulation model developed at the Danish Meteorological Institute. Comparisons of the observations and the model suggest that the neutral winds responded strongly in two height ranges. An eastward wind perturbation of ∼100 m s -1 developed between 140 and 200 km altitude with a peak near 160 km. A southwestward wind with peak magnitude of ∼150 m s -1 developed near 115 km altitude. The large amplitude winds at the lower altitude are particularly surprising. They appear to be associated with the upward propagating semidiurnal tide. However, the amplitude is much larger than predicted by any of the tidal models, and the shear found just below the peak in the winds was nomially unstable with a Richardson number of ∼0.08. 17 refs., 12 figs

  13. Radon-222 measurements aboard an airplane for the description of atmospheric diffusion

    International Nuclear Information System (INIS)

    Bogen, J.

    1973-01-01

    Radon-222 is absorbed aboard an airplane in tubes filled with 50 g of selected charcoal and cooked in Dewars by carbon dioxide and freon. After air collection at different heights up to 5 km, the tubes are evacuated and heated in the laboratory for desorption of the gas molecules and for transfer into a decay chamber covered with zinc-sulfide serving as a scintillator for the detection of alpha activity from radon-222 and its daughters. In general, the measurements show an exponential decrease of the concentration up to 5 km in height, if there is no cloud layer. The height for a reduction by a factor of two is about 900 meters. Assuming a constant diffusion coefficient K 0 up to 5 km, the measurements yield a K 0 of approximately 3.7 x 10 4 cm 2 s -1 . For flights in stratiform clouds a decrease is observed of the concentration up to a certain height, then radon-222 is again increasing or remains constant. This must be explained with respect to the meteorological situation. Assuming only a constant value for K 0 between the different flying heights, it was possible to appraise the development of the eddy diffusion coefficient with height

  14. Estimates of Terms in Ohm's Law During an Encounter with an Electron Diffusion Region

    Science.gov (United States)

    Torbert, R. B.; Burch, J. L.; Giles, B. L.; Gershman, D.; Pollock, C. J.; Dorelli, J.; Avanov, L. A.; Argall, M.; Shuster, J.; Strangeway, R.; hide

    2016-01-01

    We present measurements from the Magnetospheric Multiscale (MMS) mission taken during a reconnection event on the dayside magnetopause which includes a passage through an electron diffusion region (EDR). The four MMS satellites were separated by about 10 km such that estimates of gradients and divergences allow a reasonable estimate of terms in the generalized Ohm's law, which is key to investigating the energy dissipation during reconnection. The strength and character of dissipation mechanisms determines how magnetic energy is released. We show that both electron pressure gradients and electron inertial effects are important, but not the only participants in reconnection near EDRs, since there are residuals of a few mVm (approximately 30-50%) of E+ U(sub e) x B (from the sum of these two terms) during the encounters. These results are compared to a simulation, which exhibits many of the observed features, but where relatively little residual is present.

  15. A Reaction-Diffusion Model for Synapse Growth and Long-Term Memory

    Science.gov (United States)

    Liu, Kang; Lisman, John; Hagan, Michael

    Memory storage involves strengthening of synaptic transmission known as long-term potentiation (LTP). The late phase of LTP is associated with structural processes that enlarge the synapse. Yet, synapses must be stable, despite continual subunit turnover, over the lifetime of an encoded memory. These considerations suggest that synapses are variable-size stable structure (VSSS), meaning they can switch between multiple metastable structures with different sizes. The mechanisms underlying VSSS are poorly understood. While experiments and theory have suggested that the interplay between diffusion and receptor-scaffold interactions can lead to a preferred stable size for synaptic domains, such a mechanism cannot explain how synapses adopt widely different sizes. Here we develop a minimal reaction-diffusion model of VSSS for synapse growth, incorporating the recent observation from super-resolution microscopy that neural activity can build compositional heterogeneities within synaptic domains. We find that introducing such heterogeneities can change the stable domain size in a controlled manner. We discuss a potential connection between this model and experimental data on synapse sizes, and how it provides a possible mechanism to structurally encode graded long-term memory. We acknowledge the support from NSF INSPIRE Award number IOS-1526941 (KL, MFH, JL) and the Brandeis Center for Bioinspired Soft Materials, an NSF MRSEC, DMR- 1420382 (MFH).

  16. Atmospheric diffusion and fallout and alkaline materials produced by sodium fires

    International Nuclear Information System (INIS)

    Benfenati, I.

    1982-01-01

    The present works deals with a theoretic approach of the diffusion in air of colloidal Na 2 O coming out of sodium fires, consequent to sodium losses from the cooling circuit of a fast breeder reactor, in case of accident. The theoretical pattern has subsequently been applied to a numerical assessment of the Na 2 O concentration in air and on the ground (due to fallout), either inside or outside the sodium hall of the Cpv-1 facility at the Brasimone site. The assessment refers to the maximum credible accident 'pool burning', in the most unfavourable meteorological conditions. Protectionistic recomendations are given, and emergency procedures are described, in that concerns boot people professionally employed within the reactor site and the external population

  17. OH density measured by PLIF in a nanosecond atmospheric pressure diffuse discharge in humid air under steep high voltage pulses

    Science.gov (United States)

    Ouaras, K.; Magne, L.; Pasquiers, S.; Tardiveau, P.; Jeanney, P.; Bournonville, B.

    2018-04-01

    The spatiotemporal distributions of the OH radical density are measured using planar laser induced fluorescence in the afterglow of a nanosecond diffuse discharge at atmospheric pressure in humid air. The diffuse discharge is generated between a pin and a grounded plate electrodes within a gap of 18 mm. The high voltage pulse applied to the pin ranges from 65 to 85 kV with a rise time of 2 ns. The specific electrical energy transferred to the gas ranges from 5 to 40 J l‑1. The influence of H2O concentration is studied from 0.5% to 1.5%. An absolute calibration of OH density is performed using a six-level transient rate equation model to simulate the dynamics of OH excitation by the laser, taking into account collisional processes during the optical pumping and the fluorescence. Rayleigh scattering measurements are used to achieve the geometrical part of the calibration. A local maximum of OH density is found in the pin area whatever the operating conditions. For 85 kV and 1% of H2O, this peak reaches a value of 2.0 × 1016 cm‑3 corresponding to 8% of H2O dissociation. The temporal decay of the spatially averaged OH density is found to be similar as in the afterglow of a homogeneous photo-triggered discharge for which a self-consistent modeling is done. These tools are then used to bring discussion elements on OH kinetics.

  18. The influence of clouds and diffuse radiation on ecosystem-atmosphere CO2 and CO18O exhanges

    Energy Technology Data Exchange (ETDEWEB)

    Still, C.J.; Riley, W.J.; Biraud, S.C.; Noone, D.C.; Buenning, N.H.; Randerson, J.T.; Torn, M.S.; Welker, J.; White, J.W.C.; Vachon, R.; Farquhar, G.D.; Berry, J.A.

    2009-05-01

    This study evaluates the potential impact of clouds on ecosystem CO{sub 2} and CO{sub 2} isotope fluxes ('isofluxes') in two contrasting ecosystems (a broadleaf deciduous forest and a C{sub 4} grassland), in a region for which cloud cover, meteorological, and isotope data are available for driving the isotope-enabled land surface model, ISOLSM. Our model results indicate a large impact of clouds on ecosystem CO{sub 2} fluxes and isofluxes. Despite lower irradiance on partly cloudy and cloudy days, predicted forest canopy photosynthesis was substantially higher than on clear, sunny days, and the highest carbon uptake was achieved on the cloudiest day. This effect was driven by a large increase in light-limited shade leaf photosynthesis following an increase in the diffuse fraction of irradiance. Photosynthetic isofluxes, by contrast, were largest on partly cloudy days, as leaf water isotopic composition was only slightly depleted and photosynthesis was enhanced, as compared to adjacent clear sky days. On the cloudiest day, the forest exhibited intermediate isofluxes: although photosynthesis was highest on this day, leaf-to-atmosphere isofluxes were reduced from a feedback of transpiration on canopy relative humidity and leaf water. Photosynthesis and isofluxes were both reduced in the C{sub 4} grass canopy with increasing cloud cover and diffuse fraction as a result of near-constant light limitation of photosynthesis. These results suggest that some of the unexplained variation in global mean {delta}{sup 18}O of CO{sub 2} may be driven by large-scale changes in clouds and aerosols and their impacts on diffuse radiation, photosynthesis, and relative humidity.

  19. Formulating a problem for functions of the effect in models of atmospheric pollution with parametric consideration of diffusion in the near earth layer

    Energy Technology Data Exchange (ETDEWEB)

    Ganev, K; Yordanov, D

    1983-01-01

    The formulation of a diffusion problem for numerical models, in which the near earth layer of the atmosphere (PSA) is considered parametrically relative to the zones of pollution (the protected zones) which are also located in the near earth layer of atmosphere, is examined. In modeling atmospheric pollution, the semiempirical equation of turublent diffusion is the starting point. The results are cited of numerical calculations of the functions of the effect for the city of Sofia (the case of an even relief and the disposition of the protected zone totally within the region for which the problem is being solved). The isolines of the integral function of the effect relative to the near earth layer of the atmosphere above the city of Sofia are cited for different meteorological conditions.

  20. Prediction on long-term mean and mean square pollutant concentrations in an urban atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, S; Lamb, R G; Seinfeld, J H

    1976-01-01

    The general problem of predicting long-term average (say yearly) pollutant concentrations in an urban atmosphere is formulated. The pollutant concentration can be viewed as a random process, the complete description of which requires knowledge of its probability density function, which is unknown. The mean concentration is the first moment of the concentration distribution, and at present there exist a number of models for predicting the long-term mean concentration of an inert pollutant. The second moment, or mean square concentration, indicates additional features of the distribution, such as the level of fluctuations about the mean. In the paper a model proposed by Lamb for the long-term mean concentration is reviewed, and a new model for prediction of the long-term mean square concentration of an inert air pollutant is derived. The properties and uses of the model are discussed, and the equations defining the model are presented in a form for direct application to an urban area.

  1. Long-term orbit prediction for Tiangong-1 spacecraft using the mean atmosphere model

    Science.gov (United States)

    Tang, Jingshi; Liu, Lin; Cheng, Haowen; Hu, Songjie; Duan, Jianfeng

    2015-03-01

    China is planning to complete its first space station by 2020. For the long-term management and maintenance, the orbit of the space station needs to be predicted for a long period of time. Since the space station is expected to work in a low-Earth orbit, the error in the a priori atmosphere model contributes significantly to the rapid increase of the predicted orbit error. When the orbit is predicted for 20 days, the error in the a priori atmosphere model, if not properly corrected, could induce a semi-major axis error of up to a few kilometers and an overall position error of several thousand kilometers respectively. In this work, we use a mean atmosphere model averaged from NRLMSISE00. The a priori reference mean density can be corrected during the orbit determination. For the long-term orbit prediction, we use sufficiently long period of observations and obtain a series of the diurnal mean densities. This series contains the recent variation of the atmosphere density and can be analyzed for various periodic components. After being properly fitted, the mean density can be predicted and then applied in the orbit prediction. Here we carry out the test with China's Tiangong-1 spacecraft at the altitude of about 340 km and we show that this method is simple and flexible. The densities predicted with this approach can serve in the long-term orbit prediction. In several 20-day prediction tests, most predicted orbits show semi-major axis errors better than 700 m and overall position errors better than 400 km.

  2. Thermal neutron scattering from a hydrogen-metal system in terms of a general multi-sublattice jump diffusion model

    International Nuclear Information System (INIS)

    Kutner, R.; Sosnowska, I.

    1977-01-01

    A Multi-Sublattice Jump Diffusion Model (MSJD) for hydrogen diffusion through interstitial-site lattices is presented. The MSJD approach may, in principle, be considered as an extension of the Rowe et al (J. Phys. Chem. Solids; 32:41 (1971)) model. Jump diffusion to any neighbours with different jump times which may be asymmetric in space is discussed. On the basis of the model a new method of calculating the diffusion tensor is advanced. The quasielastic, double differential cross section for thermal neutron scattering is obtained in terms of the MSJD model. The model can be used for systems in which interstitial jump diffusion of impurity particles occurs. In Part II the theoretical results are compared with those for quasielastic neutron scattering from the αNbHsub(x) system. (author)

  3. Long-term orbit prediction for China's Tiangong-1 spacecraft based on mean atmosphere model

    Science.gov (United States)

    Tang, Jingshi; Liu, Lin; Miao, Manqian

    Tiangong-1 is China's test module for future space station. It has gone through three successful rendezvous and dockings with Shenzhou spacecrafts from 2011 to 2013. For the long-term management and maintenance, the orbit sometimes needs to be predicted for a long period of time. As Tiangong-1 works in a low-Earth orbit with an altitude of about 300-400 km, the error in the a priori atmosphere model contributes significantly to the rapid increase of the predicted orbit error. When the orbit is predicted for 10-20 days, the error in the a priori atmosphere model, if not properly corrected, could induce the semi-major axis error and the overall position error up to a few kilometers and several thousand kilometers respectively. In this work, we use a mean atmosphere model averaged from NRLMSIS00. The a priori reference mean density can be corrected during precise orbit determination (POD). For applications in the long-term orbit prediction, the observations are first accumulated. With sufficiently long period of observations, we are able to obtain a series of the diurnal mean densities. This series bears the recent variation of the atmosphere density and can be analyzed for various periods. After being properly fitted, the mean density can be predicted and then applied in the orbit prediction. We show that the densities predicted with this approach can serve to increase the accuracy of the predicted orbit. In several 20-day prediction tests, most predicted orbits show semi-major axis errors better than 700m and overall position errors better than 600km.

  4. Short- and medium-term atmospheric constituent effects of very large solar proton events

    Directory of Open Access Journals (Sweden)

    C. H. Jackman

    2008-02-01

    Full Text Available Solar eruptions sometimes produce protons, which impact the Earth's atmosphere. These solar proton events (SPEs generally last a few days and produce high energy particles that precipitate into the Earth's atmosphere. The protons cause ionization and dissociation processes that ultimately lead to an enhancement of odd-hydrogen and odd-nitrogen in the polar cap regions (>60° geomagnetic latitude. We have used the Whole Atmosphere Community Climate Model (WACCM3 to study the atmospheric impact of SPEs over the period 1963–2005. The very largest SPEs were found to be the most important and caused atmospheric effects that lasted several months after the events. We present the short- and medium-term (days to a few months atmospheric influence of the four largest SPEs in the past 45 years (August 1972; October 1989; July 2000; and October–November 2003 as computed by WACCM3 and observed by satellite instruments. Polar mesospheric NOx (NO+NO2 increased by over 50 ppbv and mesospheric ozone decreased by over 30% during these very large SPEs. Changes in HNO3, N2O5, ClONO2, HOCl, and ClO were indirectly caused by the very large SPEs in October–November 2003, were simulated by WACCM3, and previously measured by Envisat Michelson Interferometer for Passive Atmospheric Sounding (MIPAS. WACCM3 output was also represented by sampling with the MIPAS averaging kernel for a more valid comparison. Although qualitatively similar, there are discrepancies between the model and measurement with WACCM3 predicted HNO3 and ClONO2 enhancements being smaller than measured and N2O5 enhancements being larger than measured. The HOCl enhancements were fairly similar in amounts and temporal variation in WACCM3 and MIPAS. WACCM3 simulated ClO decreases below 50 km, whereas MIPAS mainly observed increases, a very perplexing difference. Upper stratospheric

  5. Optimum modellings of atmospheric diffusion of radioactive effluents and exposure doses in the accident consequence assessment (Level 3 PSA)

    International Nuclear Information System (INIS)

    Kim, Byung Woo; Lee, Young Bok; Han, Moon Hee; Kim, Eun Han; Suh, Kyung Suk; Hwang, Won Tae

    1992-12-01

    Atmospheric diffusion and exposure strongly dependent on the environment were firstly considered in the full spectrum of accident consequence assessment to establish based on Korean conditions. An optimum weather category based on Korean climate and site-specific meteorology of Kori region was established by statistical analysis of measured data for 10 years. And a trajectory model was selected as the optimal one in the ACA by reviewing several existing diffusion models. Following aspects were considered in this selection as availability of meteorological data, ability to treat the change to wind direction, easy applicability of the model, and restriction of CPU time and core memory in current computers. Numerical integration method of our own was selected as the optimal dose assessment tool of external exposure. Unit dose rate was firstly computed with this method as the function of energy level of radionuclide, size of lattice, and distance between source and receptor, and then the results were rearranged as the data library for the rapid access to the ACA run. Dynamic ecosystem modelling has been done in order to estimate the seasonal variation of radioactivity for the assessment of ingestion exposure, considering Korean ingestion behavior, agricultural practice and the transportation. There is a lot of uncertainty in a countermeasure model due to the assumed values of parameters such as fraction of population with different shielding factor and driving speed. A new countermeasure model was developed using the concept of fuzzy set theory, since it provided the mathematical tools which could characterize the uncertainty involved in countermeasure modelling. (Author)

  6. E region neutral winds in the postmidnight diffuse aurora during the atmospheric response in aurora 1 rocket campaign

    International Nuclear Information System (INIS)

    Brinkman, D.G.; Walterscheid, R.L.; Lyons, L.R.

    1995-01-01

    Measured E region neutral winds from the Atmospheric Response in Aurora (ARIA 1) rocket campaign are compared with winds predicted by a high-resolution nonhydrostatic dynamical thermosphere model. The ARIA 1 rockets were launched into the postmidnight diffuse aurora during the recovery phase of a substorm. Simulations have shown that electrodynamical coupling between the auroral ionosphere and the thermosphere was expected to be strong during active diffuse auroral conditions. This is the first time that simulations using the time history of detailed specifications of the magnitude and latitudinal variation of the auroral forcing based on measurements have been compared to simultaneous wind measurements. Model inputs included electron densities derived from ground-based airglow measurements, precipitating electron fluxes measured by the rocket, electron densities measured on the rocket, electric fields derived from magnetometer and satellite ion drift measurements, and large-scale background winds from a thermospheric general circulation model. Our model predicted a strong jet of eastward winds at E region heights. A comparison between model predicted and observed winds showed modest agreement. Above 135 km the model predicted zonal winds with the correct sense, the correct profile shape, and the correct altitude of the peak wind. However, it overpredicted the magnitude of the eastward winds by more than a factor or 2. For the meridional winds the model predicted the general sense of the winds but was unable to predict the structure or strength of the winds seen in the observations. Uncertainties in the magnitude and latitudinal structure of the electric field and in the magnitude of the background winds are the most likely sources of error contributing to the differences between model and observed winds. Between 110 and 135 km the agreement between the model and observations was poor because of a large unmodeled jetlike feature in the observed winds

  7. A comparison of short-term dispersion estimates resulting from various atmospheric stability classification methods

    International Nuclear Information System (INIS)

    Mitchell, A.E. Jr.

    1982-01-01

    Four methods of classifying atmospheric stability class are applied at four sites to make short-term (1-h) dispersion estimates from a ground-level source based on a model consistent with U.S. Nuclear Regulatory Commission practice. The classification methods include vertical temperature gradient, standard deviation of horizontal wind direction fluctuations (sigma theta), Pasquill-Turner, and modified sigma theta which accounts for meander. Results indicate that modified sigma theta yields reasonable dispersion estimates compared to those produced using methods of vertical temperature gradient and Pasquill-Turner, and can be considered as a potential economic alternative in establishing onsite monitoring programs. (author)

  8. Results of long-term measurement of 222Rn concentrations in outdoor atmosphere

    International Nuclear Information System (INIS)

    Holy, K.; Boehm, R.; Polaskova, A.; Hola, O.

    1998-01-01

    Results are reported of the authors' long-term measurement of 222 Rn concentrations in the outdoor atmosphere. The measurements started in 1987 and were performed at a height of 1.5 m over a grass-covered ground surface, using till 1991 a Lucas type scintillation chamber and later a large volume scintillation chamber. Graphs are presented and discussed of the course of average monthly radon concentration in 1987-1996 and of annual courses of radon concentration for different time intervals of the day over 1991 to 1995. (A.K.)

  9. Diffusion Tensor Imaging Correlates with Short-Term Myelopathy Outcome in Patients with Cervical Spondylotic Myelopathy.

    Science.gov (United States)

    Vedantam, Aditya; Rao, Avinash; Kurpad, Shekar N; Jirjis, Michael B; Eckardt, Gerald; Schmit, Brian D; Wang, Marjorie C

    2017-01-01

    To determine if spinal cord diffusion tensor imaging indexes correlate with short-term clinical outcome in patients undergoing elective cervical spine surgery for cervical spondylotic myelopathy (CSM). A prospective consecutive cohort study was performed in patients undergoing elective cervical spine surgery for CSM. After obtaining informed consent, patients with CSM underwent preoperative T2-weighted magnetic resonance imaging and diffusion tensor imaging of the cervical spine. Fractional anisotropy (FA) values at the level of maximum cord compression and at the noncompressed C1-2 level were calculated on axial images. We recorded the modified Japanese Orthopaedic Association (mJOA) scale, Neck Disability Index, and Short Form-36 physical functioning subscale scores for all patients preoperatively and 3 months postoperatively. Statistical analysis was performed to identify correlations between FA and clinical outcome scores. The study included 27 patients (mean age 54.5 years ± 1.9, 12 men). The mean postoperative changes in mJOA scale, Neck Disability Index, and Short Form-36 physical functioning subscale scores were 0.9 ± 0.3, -6.0 ± 1.9, and 3.4 ± 1.9. The mean FA at the level of maximum compression was significantly lower than the mean FA at the C1-2 level (0.5 vs. 0.55, P = 0.01). FA was significantly correlated with change in mJOA scale score (Pearson r = -0.42, P = 0.02). FA was significantly correlated with the preoperative mJOA scale score (Pearson r = 0.65, P < 0.001). Preoperative FA at the level of maximum cord compression significantly correlates with the 3-month change in mJOA scale score among patients with CSM. FA was also significantly associated with preoperative mJOA scale score and is a potential biomarker for spinal cord dysfunction in CSM. Published by Elsevier Inc.

  10. Short- and Medium-term Atmospheric Effects of Very Large Solar Proton Events

    Science.gov (United States)

    Jackman, Charles H.; Marsh, Daniel R.; Vitt, Francis M.; Garcia, Rolando R.; Fleming, Eric L.; Labow, Gordon J.; Randall, Cora E.; Lopez-Puertas, Manuel; Funke, Bernd

    2007-01-01

    Long-term variations in ozone have been caused by both natural and humankind related processes. In particular, the humankind or anthropogenic influence on ozone from chlorofluorocarbons and halons (chlorine and bromine) has led to international regulations greatly limiting the release of these substances. These anthropogenic effects on ozone are most important in polar regions and have been significant since the 1970s. Certain natural ozone influences are also important in polar regions and are caused by the impact of solar charged particles on the atmosphere. Such natural variations have been studied in order to better quantify the human influence on polar ozone. Large-scale explosions on the Sun near solar maximum lead to emissions of charged particles (mainly protons and electrons), some of which enter the Earth's magnetosphere and rain down on the polar regions. "Solar proton events" have been used to describe these phenomena since the protons associated with these solar events sometimes create a significant atmospheric disturbance. We have used the National Center for Atmospheric Research (NCAR) Whole Atmosphere Community Climate Model (WACCM) to study the short- and medium-term (days to a few months) influences of solar proton events between 1963 and 2005 on stratospheric ozone. The four largest events in the past 45 years (August 1972; October 1989; July 2000; and October-November 2003) caused very distinctive polar changes in layers of the Earth's atmosphere known as the stratosphere (12-50 km; -7-30 miles) and mesosphere (50-90 km; 30-55 miles). The solar protons connected with these events created hydrogen- and nitrogen- containing compounds, which led to the polar ozone destruction. The hydrogen-containing compounds have very short lifetimes and lasted for only a few days (typically the duration of the solar proton event). On the other hand, the nitrogen-containing compounds lasted much longer, especially in the Winter. The nitrogen oxides were predicted

  11. The Long-term Middle Atmospheric Influence of Very Large Solar Proton Events

    Science.gov (United States)

    Jackman, Charles H.; Marsh, Daniel R.; Vitt, Francis M.; Garcia, Rolando R.; Randall, Cora E.; Fleming, Eric L.; Frith, Stacey M.

    2008-01-01

    Long-term variations in ozone have been caused by both natural and humankind related processes. The humankind or anthropogenic influence on ozone originates from the chlorofluorocarbons and halons (chlorine and bromine) and has led to international regulations greatly limiting the release of these substances. Certain natural ozone influences are also important in polar regions and are caused by the impact of solar charged particles on the atmosphere. Such natural variations have been studied in order to better quantify the human influence on polar ozone. Large-scale explosions on the Sun near solar maximum lead to emissions of charged particles (mainly protons and electrons), some of which enter the Earth's magnetosphere and rain down on the polar regions. "Solar proton events" have been used to describe these phenomena since the protons associated with these solar events sometimes create a significant atmospheric disturbance. We have used the National Center for Atmospheric Research (NCAR) Whole Atmosphere Community Climate Model (WACCM) to study the long-term (> few months) influences of solar proton events from 1963 through 2004 on stratospheric ozone and temperature. There were extremely large solar proton events in 1972, 1989,2000,2001, and 2003. These events caused very distinctive polar changes in layers of the Earth's atmosphere known as the stratosphere (12-50 km; -7-30 miles) and mesosphere (50-90 km; 30-55 miles). The solar protons connected with these events created hydrogen- and nitrogen-containing compounds, which led to the polar ozone destruction. The nitrogen-containing compounds, called odd nitrogen, lasted much longer than the hydrogen-containing compounds and led to long-lived stratospheric impacts. An extremely active period for these events occurred in the five-year period, 2000- 2004, and caused increases in odd nitrogen which lasted for several months after individual events. Associated stratospheric ozone decreases of >lo% were calculated

  12. Global exponential stability of impulsive fuzzy cellular neural networks with mixed delays and reaction-diffusion terms

    International Nuclear Information System (INIS)

    Wang Xiaohu; Xu Daoyi

    2009-01-01

    In this paper, the global exponential stability of impulsive fuzzy cellular neural networks with mixed delays and reaction-diffusion terms is considered. By establishing an integro-differential inequality with impulsive initial condition and using the properties of M-cone and eigenspace of the spectral radius of nonnegative matrices, several new sufficient conditions are obtained to ensure the global exponential stability of the equilibrium point for fuzzy cellular neural networks with delays and reaction-diffusion terms. These results extend and improve the earlier publications. Two examples are given to illustrate the efficiency of the obtained results.

  13. Mid-latitude summer response of the middle atmosphere to short-term solar UV changes

    Directory of Open Access Journals (Sweden)

    P. Keckhut

    1995-06-01

    Full Text Available Temperature and wind data obtained with Rayleigh lidar since 1979 and Russian rockets since 1964 are analyzed to deduce the summer response of the middle atmosphere to short-term solar UV changes. The equivalent width of the 1083 nm He I line is used as a proxy to monitor the short-term UV flux changes. Spectral analyses are performed on 108-day windows to extract the 27-day component from temperature, wind and solar data sets. Linear regressions between these spectral harmonics show some significant correlations around 45 km at mid-latitudes. For large 27-day solar cycles, amplitudes of 2 K and 6 m s-1 are calculated for temperature data series over the south of France (44°N, and on wind data series over Volgograd (49°N, respectively. Cross-spectrum analyses have indicated correlations between these atmospheric parameters and the solar proxy with a phase lag of less than 2 days. These statistically correlative results, which provide good qualitative agreement with numerical simulations, are both obtained at mid-latitude. However, the observed amplitudes are larger than expected, with numerical models suggesting that dynamical processes such as equatorial or gravity waves may be responsible.

  14. Mid-latitude summer response of the middle atmosphere to short-term solar UV changes

    Directory of Open Access Journals (Sweden)

    P. Keckhut

    Full Text Available Temperature and wind data obtained with Rayleigh lidar since 1979 and Russian rockets since 1964 are analyzed to deduce the summer response of the middle atmosphere to short-term solar UV changes. The equivalent width of the 1083 nm He I line is used as a proxy to monitor the short-term UV flux changes. Spectral analyses are performed on 108-day windows to extract the 27-day component from temperature, wind and solar data sets. Linear regressions between these spectral harmonics show some significant correlations around 45 km at mid-latitudes. For large 27-day solar cycles, amplitudes of 2 K and 6 m s-1 are calculated for temperature data series over the south of France (44°N, and on wind data series over Volgograd (49°N, respectively. Cross-spectrum analyses have indicated correlations between these atmospheric parameters and the solar proxy with a phase lag of less than 2 days. These statistically correlative results, which provide good qualitative agreement with numerical simulations, are both obtained at mid-latitude. However, the observed amplitudes are larger than expected, with numerical models suggesting that dynamical processes such as equatorial or gravity waves may be responsible.

  15. Analysis and experimental study on formation conditions of large-scale barrier-free diffuse atmospheric pressure air plasmas in repetitive pulse mode

    Science.gov (United States)

    Li, Lee; Liu, Lun; Liu, Yun-Long; Bin, Yu; Ge, Ya-Feng; Lin, Fo-Chang

    2014-01-01

    Atmospheric air diffuse plasmas have enormous application potential in various fields of science and technology. Without dielectric barrier, generating large-scale air diffuse plasmas is always a challenging issue. This paper discusses and analyses the formation mechanism of cold homogenous plasma. It is proposed that generating stable diffuse atmospheric plasmas in open air should meet the three conditions: high transient power with low average power, excitation in low average E-field with locally high E-field region, and multiple overlapping electron avalanches. Accordingly, an experimental configuration of generating large-scale barrier-free diffuse air plasmas is designed. Based on runaway electron theory, a low duty-ratio, high voltage repetitive nanosecond pulse generator is chosen as a discharge excitation source. Using the wire-electrodes with small curvature radius, the gaps with highly non-uniform E-field are structured. Experimental results show that the volume-scaleable, barrier-free, homogeneous air non-thermal plasmas have been obtained between the gap spacing with the copper-wire electrodes. The area of air cold plasmas has been up to hundreds of square centimeters. The proposed formation conditions of large-scale barrier-free diffuse air plasmas are proved to be reasonable and feasible.

  16. Fourth order Douglas implicit scheme for solving three dimension reaction diffusion equation with non-linear source term

    Directory of Open Access Journals (Sweden)

    Shahid Hasnain

    2017-07-01

    Full Text Available This research paper represents a numerical approximation to non-linear three dimension reaction diffusion equation with non-linear source term from population genetics. Since various initial and boundary value problems exist in three dimension reaction diffusion phenomena, which are studied numerically by different numerical methods, here we use finite difference schemes (Alternating Direction Implicit and Fourth Order Douglas Implicit to approximate the solution. Accuracy is studied in term of L2, L∞ and relative error norms by random selected grids along time levels for comparison with analytical results. The test example demonstrates the accuracy, efficiency and versatility of the proposed schemes. Numerical results showed that Fourth Order Douglas Implicit scheme is very efficient and reliable for solving 3-D non-linear reaction diffusion equation.

  17. Fourth order Douglas implicit scheme for solving three dimension reaction diffusion equation with non-linear source term

    Science.gov (United States)

    Hasnain, Shahid; Saqib, Muhammad; Mashat, Daoud Suleiman

    2017-07-01

    This research paper represents a numerical approximation to non-linear three dimension reaction diffusion equation with non-linear source term from population genetics. Since various initial and boundary value problems exist in three dimension reaction diffusion phenomena, which are studied numerically by different numerical methods, here we use finite difference schemes (Alternating Direction Implicit and Fourth Order Douglas Implicit) to approximate the solution. Accuracy is studied in term of L2, L∞ and relative error norms by random selected grids along time levels for comparison with analytical results. The test example demonstrates the accuracy, efficiency and versatility of the proposed schemes. Numerical results showed that Fourth Order Douglas Implicit scheme is very efficient and reliable for solving 3-D non-linear reaction diffusion equation.

  18. Determination of the safety zones of Angra dos Reis Nuclear Power Plant, according to the model of radion diffusion in the atmosphere

    International Nuclear Information System (INIS)

    Santina, M.D.

    1978-01-01

    The safety distance for Angra dos Reis Nuclear Power Plant are calculated, based on the model of the maximum credible accident for PWR power reactors and on the calculation of the dose due to hypothetical accidental release of radioactivity, using the model of radiation dispersion in the atmosphere. The safety distances for the Angra dos Reis reactors are also calculated using the model of the nine accident categories of the Rasmussen Report. The values of probability associated to each type of accident are used with the respective fractions of radiation release to the atmosphere. The soil contamination is also calculated for all the accidents considered and for several conditions of atmospheric stability, according to the model developed by Chamberlain. The program ACRA-II is used for calculation of the diffusion of radiation in the atmosphere, and the doses associated to it [pt

  19. Diffusion-type model of the global carbon cycle for the estimation of dose to the world population from releases of carbon-14 to the atmosphere

    International Nuclear Information System (INIS)

    Killough, G.G.

    1977-05-01

    A nonlinear dynamic model of the exchange of carbon among the atmosphere, terrestrial biosphere, and ocean is described and applied to estimating the radiation dose to the world's population from the release of 14 C to the atmosphere from the nuclear power industry. A computer implementation of the model, written in the IBM Continuous System Modeling Program III (CSMP III) simulation language, is presented. The model treats the ocean as a diffusive medium with respect to vertical transport of carbon, and the nonlinear variation of CO 2 partial pressure with the total inorganic carbon concentration in surface waters is taken into account in calculating the transfer rate from ocean to atmosphere. Transfers between the atmosphere and terrestrial biosphere are represented by nonlinear equations which consider CO 2 fertilization and impose a constraint on the ultimate total carbon mass in the biosphere

  20. A Diffusion Model Analysis of Adult Age Differences in Episodic and Semantic Long-Term Memory Retrieval

    Science.gov (United States)

    Spaniol, Julia; Madden, David J.; Voss, Andreas

    2006-01-01

    Two experiments investigated adult age differences in episodic and semantic long-term memory tasks, as a test of the hypothesis of specific age-related decline in context memory. Older adults were slower and exhibited lower episodic accuracy than younger adults. Fits of the diffusion model (R. Ratcliff, 1978) revealed age-related increases in…

  1. Lithosphere-atmosphere-ionosphere coupling as governing mechanism for preseismic short-term events in atmosphere and ionosphere

    Directory of Open Access Journals (Sweden)

    O. Molchanov

    2004-01-01

    Full Text Available We present a general concept of mechanisms of preseismic phenomena in the atmosphere and ionosphere. After short review of observational results we conclude: 1. Upward migration of fluid substrate matter (bubble can lead to ousting of the hot water/gas near the ground surface and cause an earthquake (EQ itself in the strength-weakened area; 2. Thus, time and place of the bubble appearance could be random values, but EQ, geochemistry anomaly and foreshocks (seismic, SA and ULF electromagnetic ones are casually connected; 3. Atmospheric perturbation of temperature and density could follow preseismic hot water/gas release resulting in generation of atmospheric gravity waves (AGW with periods in a range of 6–60min; 4. Seismo-induced AGW could lead to modification of the ionospheric turbulence and to the change of over-horizon radio-wave propagation in the atmosphere, perturbation of LF waves in the lower ionosphere and ULF emission depression at the ground.

  2. A Long-term Forest Fertilization Experiment to Understand Ecosystem Responses to Atmospheric Nitrogen Deposition

    Science.gov (United States)

    Baron, J.; Advani, S. M.; Allen, J.; Boot, C.; Denef, K.; Denning, S.; Hall, E.; Moore, J. C.; Reuth, H.; Ryan, M. G.; Shaw, E.

    2016-12-01

    Long-term field experiments can reveal changes in ecosystem processes that may not be evident in short-term studies. Short-term measurements or experiments may have narrower objectives or unrealistic treatments in order to see a change, whereas long-term studies can reveal complex interactions that take longer to manifest. We report results from a long-term experiment (1996 to present) in subalpine forests to simulate the consequences of sustained atmospheric nitrogen (N) deposition. Loch Vale watershed in Rocky Mountain National Park, the location of the experiment, has received an order of magnitude greater atmospheric N deposition than estimated background since mid-20th Century. Augmenting that, in 1996 we began adding 25 kg NH4NO3 ha-1 yr-1 to three 30m x 30m old-growth Engelmann spruce and subalpine fir plots. Treated stands were matched by nearby controls. N addition caused rapid leaching of nitrate and cations from soils, and increased N mineralization and nitrification rates. These observations in the fertilized plots have been sustained over time. Soluble aluminum concentrations do not differ significantly between fertilized and control plots, but treated soils are now markedly more acidic (pH of 4.7) than original soil and controls (pH of 5.1); further acidification might increase aluminum leaching. Effects on soil carbon were complex, mediated by reductions in total microbial biomass, decreases in arbuscular mychorrizal and saprotropic fungi, and increased potential rates of N enzyme degrading activities. Initial soil C:N of 24 was lower than similar soils in low N deposition stands (C:N of 36). The C:N declined to 22 with treatment. Fertilized plots lost 11% soil C, but the mechanism is unclear. We did not measure changes in C inputs from litter, microbial biomass, or plant uptake, but there was no change in summer CO2 flux, measured in 2003, 2004, and 2014. Leaching of DOC from fertilized plots was elevated throughout the experiment, providing one

  3. Long-term record of top-of-atmosphere albedo generated from AVHRR data

    Science.gov (United States)

    Song, Z.

    2017-12-01

    Top-of-Atmosphere (TOA) albedo is a fundamental component of Earth's energy budget. Previously, long-term accurate TOA albedo products did not exist due to the lack of stable broadband observations. With a new albedo estimation methodology based on multispectral observations, TOA albedo since 1981 has been retrieved using data from the Advanced Very High Resolution Radiometer (AVHRR), which provides the longest record of satellite observations across the globe. To develop the long-term TOA albedo record, the instantaneous TOA albedo was calculated by the direct estimation method, which was built on training data pairs from coincident AVHRR TOA reflectance and Moderate Resolution Imaging Spectroradiometer (MODIS) TOA albedo. The instantaneous TOA albedo was then converted to daily mean and monthly mean albedo based on the diurnal curves from geostationary satellites. The TOA albedo results (AVHRR-TAL) were compared with Clouds and the Earth's Radiant Energy System (CERES) flux products for 2007. The monthly mean AVHRR-TAL agreed well with the CERES products, with a root mean square difference (RMSD) of 0.032 and a bias of 0.013. In addition, AVHRR-TAL showed similar seasonal variations to those seen in the CERES products. Further analysis on long-term time series showed good consistency between the two datasets (R2 > 0.95 and relative RMSD < 4%) from 2000 to 2015. Although some calibration issues remain to be solved, our datasets show the potential ability to observe the global TOA albedo from 1981 to the present.

  4. A source term estimation method for a nuclear accident using atmospheric dispersion models

    DEFF Research Database (Denmark)

    Kim, Minsik; Ohba, Ryohji; Oura, Masamichi

    2015-01-01

    The objective of this study is to develop an operational source term estimation (STE) method applicable for a nuclear accident like the incident that occurred at the Fukushima Dai-ichi nuclear power station in 2011. The new STE method presented here is based on data from atmospheric dispersion...... models and short-range observational data around the nuclear power plants.The accuracy of this method is validated with data from a wind tunnel study that involved a tracer gas release from a scaled model experiment at Tokai Daini nuclear power station in Japan. We then use the methodology developed...... and validated through the effort described in this manuscript to estimate the release rate of radioactive material from the Fukushima Dai-ichi nuclear power station....

  5. Long-term trend and variability of atmospheric PM10 concentration in the Po Valley

    Science.gov (United States)

    Bigi, A.; Ghermandi, G.

    2014-05-01

    The limits to atmospheric pollutant concentration set by the European Commission provide a challenging target for the municipalities in the Po Valley, because of the characteristic climatic conditions and high population density of this region. In order to assess climatology and trends in the concentration of atmospheric particles in the Po Valley, a data set of PM10 data from 41 sites across the Po Valley have been analysed, including both traffic and background sites (either urban, suburban or rural). Of these 41 sites, 18 with 10 yr or longer record have been analysed for long-term trend in deseasonalized monthly means, in annual quantiles and in monthly frequency distribution. A widespread significant decreasing trend has been observed at most sites, up to a few percent per year, by a generalized least squares and Theil-Sen method. All 41 sites have been tested for significant weekly periodicity by Kruskal-Wallis test for mean anomalies and by Wilcoxon test for weekend effect magnitude. A significant weekly periodicity has been observed for most PM10 series, particularly in summer and ascribed mainly to anthropic particulate emissions. A cluster analysis has been applied in order to highlight stations sharing similar pollution conditions over the reference period. Five clusters have been found, two encompassing the metropolitan areas of Turin and Milan and their respective nearby sites and the other three clusters gathering northeast, northwest and central Po Valley sites respectively. Finally, the observed trends in atmospheric PM10 have been compared to trends in provincial emissions of particulates and PM precursors, and analysed along with data on vehicular fleet age, composition and fuel sales. A significant basin-wide drop in emissions occurred for gaseous pollutants, contrarily to emissions of PM10 and PM2.5, whose drop was low and restricted to a few provinces. It is not clear whether the decrease for only gaseous emissions is sufficient to explain the

  6. Modelling cointegration and Granger causality network to detect long-term equilibrium and diffusion paths in the financial system.

    Science.gov (United States)

    Gao, Xiangyun; Huang, Shupei; Sun, Xiaoqi; Hao, Xiaoqing; An, Feng

    2018-03-01

    Microscopic factors are the basis of macroscopic phenomena. We proposed a network analysis paradigm to study the macroscopic financial system from a microstructure perspective. We built the cointegration network model and the Granger causality network model based on econometrics and complex network theory and chose stock price time series of the real estate industry and its upstream and downstream industries as empirical sample data. Then, we analysed the cointegration network for understanding the steady long-term equilibrium relationships and analysed the Granger causality network for identifying the diffusion paths of the potential risks in the system. The results showed that the influence from a few key stocks can spread conveniently in the system. The cointegration network and Granger causality network are helpful to detect the diffusion path between the industries. We can also identify and intervene in the transmission medium to curb risk diffusion.

  7. Effects of long-term elevated atmospheric CO2 concentrations on Pinus ponderosa

    International Nuclear Information System (INIS)

    Surano, K.A.; Kercher, J.R.

    1993-01-01

    This report details the results from an experiment of the effects of long-term elevated atmospheric CO 2 concentrations on ponderosa pine (Pinus ponderosa Laws.) saplings and seedlings. The study began in 1983 as a pilot study designed to explore the feasibility of using open-top chambers for continuous multi-year exposures on sapling-sized trees and to examine possible CO 2 responses so that future research could be adequately designed. however, following the first year of exposure, preliminary results from the study indicated that measurements of CO 2 responses should be intensified. Open-top chambers proved suitable for use in multiyear exposures of mature trees. With respect to the preliminary examination of CO 2 responses, many interesting observations were made. The nature of the preliminary results suggests that future long-term field CO 2 exposures on perennial species may be critical to the understanding and preparation for future environments. Other research reported here attempted to adapt an existing western coniferous forest growth and succession model for use in elevated CO 2 scenarios using differential species responses, and assessed the usefulness of the model in that regard. Seven papers have been processed separately for inclusion in the appropriate data bases

  8. Effects of long-term elevated atmospheric CO{sub 2} concentrations on Pinus ponderosa

    Energy Technology Data Exchange (ETDEWEB)

    Surano, K.A.; Kercher, J.R. [eds.

    1993-10-01

    This report details the results from an experiment of the effects of long-term elevated atmospheric CO{sub 2} concentrations on ponderosa pine (Pinus ponderosa Laws.) saplings and seedlings. The study began in 1983 as a pilot study designed to explore the feasibility of using open-top chambers for continuous multi-year exposures on sapling-sized trees and to examine possible CO{sub 2} responses so that future research could be adequately designed. however, following the first year of exposure, preliminary results from the study indicated that measurements of CO{sub 2} responses should be intensified. Open-top chambers proved suitable for use in multiyear exposures of mature trees. With respect to the preliminary examination of CO{sub 2} responses, many interesting observations were made. The nature of the preliminary results suggests that future long-term field CO{sub 2} exposures on perennial species may be critical to the understanding and preparation for future environments. Other research reported here attempted to adapt an existing western coniferous forest growth and succession model for use in elevated CO{sub 2} scenarios using differential species responses, and assessed the usefulness of the model in that regard. Seven papers have been processed separately for inclusion in the appropriate data bases.

  9. Long-term atmospheric visibility trend in Southeast China, 1973-2010

    Science.gov (United States)

    Deng, Junjun; Du, Ke; Wang, Kai; Yuan, Chung-Shin; Zhao, Juanjuan

    2012-11-01

    Particulate matter (PM) pollution in Southeast China has been worsening because of the rapid industrial development and urbanization, which have significant negative effects on atmospheric visibility. Characterization of the trend in atmospheric visibility is important for evaluating the impact of PM pollution on the impairment of visual air quality in urban and rural areas. Long-term trend in atmospheric visibility in Southeast China was analyzed for the period of 1973-2010 based on the meteorological data from the National Climatic Data Center (NCDC) database using four statistical methods: annual mean visibility, percentages of “very good” visibility and “bad” visibility, ridit analysis, and cumulative percentiles. The relationship of atmospheric extinction with Air Pollution Index (API) was studied. In addition, the effects of recent environment policies on visibility were studied. The results showed that the visibility had decreased in 94% stations of this region and prefecture stations had the highest decreasing trend of -3.1 km/decade during the entire period. The average visibility of all the 17 stations (i.e., region-average) declined at a rate of -2.0 km/decade, with a 38-year average of 18.1 km. Decrease in the percentage of “very good” visibility and increase in the percentage of “bad” visibility existed in 14 and 16 stations, respectively. Region-average percentage of “bad” visibility was in the range of 2.2-21.5%, with an increasing rate of 5.0% per decade, and that of “very good” visibility was 24.4-71.8%, with a decreasing rate of -10.7% per decade. During the entire period, county and prefecture stations had similar changing patterns and trends in visibility, while town stations had the least worsening trends. Region-average visibility was better before 1988 while worse after 1993 when comparing to the entire period, with the transition period of 1988-1993. The worst 20%, 50% and best 20% of region-average visibility

  10. Atmospheric carbon dioxide and the long-term control of the Earth's climate

    Directory of Open Access Journals (Sweden)

    J. H. Carver

    1995-07-01

    Full Text Available A CO2-weathering model has been used to explore the possible evolution of the Earth's climate as the Sun steadily brightened throughout geologic time. The results of the model calculations can be described in terms of three, qualitatively different, "Megaclimates". Mega-climate 1 resulted from a period of rapid outgassing in the early Archean, with high, but declining, temperatures caused by the small weathering rates on a largely water-covered planet. Mega-climate 2 began about 3 Gyear ago as major continental land masses developed, increasing the weathering rate in the early Proterozoic and thereby depleting the atmospheric CO2 concentration. This process produced the first Precambrian glaciations about 2.3 Gyear ago. During Mega-climate 2, evolutionary biological processes increased the surface weatherability in incremental steps and plate tectonics modulated the CO2 outgassing rate with an estimated period of 150 Myear (approximately one-half the period for the formation and breakup of super continents. Throughout Mega-climate 2 the surface temperature was controlled by variations in the atmospheric CO2 level allowing transitions between glacial and non-glacial conditions. The results of the model for Mega-climate 2 are in agreement with the occurrence (and absence of glaciations in the geologic record. Extending the model to the future suggests that CO2 control of the Earth's temperature will no longer be able to compensate for a solar flux that continues to increase. The present level of atmospheric CO2 is so small that further reduction in CO2 cannot prevent the Earth from experiencing Mega-climate 3 with steadily increasing surface temperatures caused by the continued brightening of the Sun. During Mega-climate 3, the main danger to the biosphere would come not from an increasing temperature but from a decreasing (rather than an increasing CO2 level which could, in time, fall below 0.5 PAL, causing serious damage to the biosphere

  11. Atmospheric carbon dioxide and the long-term control of the Earth's climate

    Directory of Open Access Journals (Sweden)

    J. H. Carver

    Full Text Available A CO2-weathering model has been used to explore the possible evolution of the Earth's climate as the Sun steadily brightened throughout geologic time. The results of the model calculations can be described in terms of three, qualitatively different, "Megaclimates". Mega-climate 1 resulted from a period of rapid outgassing in the early Archean, with high, but declining, temperatures caused by the small weathering rates on a largely water-covered planet. Mega-climate 2 began about 3 Gyear ago as major continental land masses developed, increasing the weathering rate in the early Proterozoic and thereby depleting the atmospheric CO2 concentration. This process produced the first Precambrian glaciations about 2.3 Gyear ago. During Mega-climate 2, evolutionary biological processes increased the surface weatherability in incremental steps and plate tectonics modulated the CO2 outgassing rate with an estimated period of 150 Myear (approximately one-half the period for the formation and breakup of super continents. Throughout Mega-climate 2 the surface temperature was controlled by variations in the atmospheric CO2 level allowing transitions between glacial and non-glacial conditions. The results of the model for Mega-climate 2 are in agreement with the occurrence (and absence of glaciations in the geologic record. Extending the model to the future suggests that CO2 control of the Earth's temperature will no longer be able to compensate for a solar flux that continues to increase. The present level of atmospheric CO2 is so small that further reduction in CO2 cannot prevent the Earth from experiencing Mega-climate 3 with steadily increasing surface temperatures caused by the continued brightening of the Sun. During Mega-climate 3, the main danger to the biosphere would come not from an increasing temperature but from a decreasing (rather than an increasing CO2

  12. Short-term evolution of spinal cord damage in multiple sclerosis: a diffusion tensor MRI study

    Energy Technology Data Exchange (ETDEWEB)

    Theaudin, M.; Denier, C.; Adams, D. [AP-HP, CHU Bicetre, Service de Neurologie Adultes, Le Kremlin-Bicetre (France); INSERM, UMR788, Faculte de Medecine Paris Sud, Le Kremlin-Bicetre (France); Saliou, G. [AP-HP, CHU Bicetre, Service de Neuroradiologie, Le Kremlin-Bicetre (France); Ducot, B. [INSERM, U1018, CESP Centre for Research in Epidemiology and Population Health, Faculte de Medecine Paris Sud, Le Kremlin-Bicetre (France); Deiva, K. [Service de Neuropediatrie, Le Kremlin-Bicetre (France); Ducreux, D. [INSERM, UMR788, Faculte de Medecine Paris Sud, Le Kremlin-Bicetre (France); AP-HP, CHU Bicetre, Service de Neuroradiologie, Le Kremlin-Bicetre (France)

    2012-10-15

    The potential of diffusion tensor imaging (DTI) to detect spinal cord abnormalities in patients with multiple sclerosis has already been demonstrated. The objective of this study was to apply DTI techniques to multiple sclerosis patients with a recently diagnosed spinal cord lesion, in order to demonstrate a correlation between variations of DTI parameters and clinical outcome, and to try to identify DTI parameters predictive of outcome. A prospective single-centre study of patients with spinal cord relapse treated by intravenous steroid therapy was made. Patients were assessed clinically and by conventional MRI with DTI sequences at baseline and at 3 months. Sixteen patients were recruited. At 3 months, 12 patients were clinically improved. All but one patient had lower fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values than normal subjects in either inflammatory lesions or normal-appearing spinal cord. Patients who improved at 3 months presented a significant reduction in the radial diffusivity (p = 0.05) in lesions during the follow-up period. They also had a significant reduction in the mean ADC (p = 0.002), axial diffusivity (p = 0.02), radial diffusivity (p = 0.02) and a significant increase in FA values (p = 0.02) in normal-appearing spinal cord. Patients in whom the American Spinal Injury Association sensory score improved at 3 months showed a significantly higher FA (p = 0.009) and lower radial diffusivity (p = 0.04) in inflammatory lesion at baseline compared to patients with no improvement. DTI MRI detects more extensive abnormalities than conventional T2 MRI. A less marked decrease in FA value and more marked decreased in radial diffusivity inside the inflammatory lesion were associated with better outcome. (orig.)

  13. Short-term evolution of spinal cord damage in multiple sclerosis: a diffusion tensor MRI study

    International Nuclear Information System (INIS)

    Theaudin, M.; Denier, C.; Adams, D.; Saliou, G.; Ducot, B.; Deiva, K.; Ducreux, D.

    2012-01-01

    The potential of diffusion tensor imaging (DTI) to detect spinal cord abnormalities in patients with multiple sclerosis has already been demonstrated. The objective of this study was to apply DTI techniques to multiple sclerosis patients with a recently diagnosed spinal cord lesion, in order to demonstrate a correlation between variations of DTI parameters and clinical outcome, and to try to identify DTI parameters predictive of outcome. A prospective single-centre study of patients with spinal cord relapse treated by intravenous steroid therapy was made. Patients were assessed clinically and by conventional MRI with DTI sequences at baseline and at 3 months. Sixteen patients were recruited. At 3 months, 12 patients were clinically improved. All but one patient had lower fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values than normal subjects in either inflammatory lesions or normal-appearing spinal cord. Patients who improved at 3 months presented a significant reduction in the radial diffusivity (p = 0.05) in lesions during the follow-up period. They also had a significant reduction in the mean ADC (p = 0.002), axial diffusivity (p = 0.02), radial diffusivity (p = 0.02) and a significant increase in FA values (p = 0.02) in normal-appearing spinal cord. Patients in whom the American Spinal Injury Association sensory score improved at 3 months showed a significantly higher FA (p = 0.009) and lower radial diffusivity (p = 0.04) in inflammatory lesion at baseline compared to patients with no improvement. DTI MRI detects more extensive abnormalities than conventional T2 MRI. A less marked decrease in FA value and more marked decreased in radial diffusivity inside the inflammatory lesion were associated with better outcome. (orig.)

  14. Long-term functional outcomes and correlation with regional brain connectivity by MRI diffusion tractography metrics in a near-term rabbit model of intrauterine growth restriction.

    Directory of Open Access Journals (Sweden)

    Miriam Illa

    Full Text Available BACKGROUND: Intrauterine growth restriction (IUGR affects 5-10% of all newborns and is associated with increased risk of memory, attention and anxiety problems in late childhood and adolescence. The neurostructural correlates of long-term abnormal neurodevelopment associated with IUGR are unknown. Thus, the aim of this study was to provide a comprehensive description of the long-term functional and neurostructural correlates of abnormal neurodevelopment associated with IUGR in a near-term rabbit model (delivered at 30 days of gestation and evaluate the development of quantitative imaging biomarkers of abnormal neurodevelopment based on diffusion magnetic resonance imaging (MRI parameters and connectivity. METHODOLOGY: At +70 postnatal days, 10 cases and 11 controls were functionally evaluated with the Open Field Behavioral Test which evaluates anxiety and attention and the Object Recognition Task that evaluates short-term memory and attention. Subsequently, brains were collected, fixed and a high resolution MRI was performed. Differences in diffusion parameters were analyzed by means of voxel-based and connectivity analysis measuring the number of fibers reconstructed within anxiety, attention and short-term memory networks over the total fibers. PRINCIPAL FINDINGS: The results of the neurobehavioral and cognitive assessment showed a significant higher degree of anxiety, attention and memory problems in cases compared to controls in most of the variables explored. Voxel-based analysis (VBA revealed significant differences between groups in multiple brain regions mainly in grey matter structures, whereas connectivity analysis demonstrated lower ratios of fibers within the networks in cases, reaching the statistical significance only in the left hemisphere for both networks. Finally, VBA and connectivity results were also correlated with functional outcome. CONCLUSIONS: The rabbit model used reproduced long-term functional impairments and their

  15. Long-term functional outcomes and correlation with regional brain connectivity by MRI diffusion tractography metrics in a near-term rabbit model of intrauterine growth restriction.

    Science.gov (United States)

    Illa, Miriam; Eixarch, Elisenda; Batalle, Dafnis; Arbat-Plana, Ariadna; Muñoz-Moreno, Emma; Figueras, Francesc; Gratacos, Eduard

    2013-01-01

    Intrauterine growth restriction (IUGR) affects 5-10% of all newborns and is associated with increased risk of memory, attention and anxiety problems in late childhood and adolescence. The neurostructural correlates of long-term abnormal neurodevelopment associated with IUGR are unknown. Thus, the aim of this study was to provide a comprehensive description of the long-term functional and neurostructural correlates of abnormal neurodevelopment associated with IUGR in a near-term rabbit model (delivered at 30 days of gestation) and evaluate the development of quantitative imaging biomarkers of abnormal neurodevelopment based on diffusion magnetic resonance imaging (MRI) parameters and connectivity. At +70 postnatal days, 10 cases and 11 controls were functionally evaluated with the Open Field Behavioral Test which evaluates anxiety and attention and the Object Recognition Task that evaluates short-term memory and attention. Subsequently, brains were collected, fixed and a high resolution MRI was performed. Differences in diffusion parameters were analyzed by means of voxel-based and connectivity analysis measuring the number of fibers reconstructed within anxiety, attention and short-term memory networks over the total fibers. The results of the neurobehavioral and cognitive assessment showed a significant higher degree of anxiety, attention and memory problems in cases compared to controls in most of the variables explored. Voxel-based analysis (VBA) revealed significant differences between groups in multiple brain regions mainly in grey matter structures, whereas connectivity analysis demonstrated lower ratios of fibers within the networks in cases, reaching the statistical significance only in the left hemisphere for both networks. Finally, VBA and connectivity results were also correlated with functional outcome. The rabbit model used reproduced long-term functional impairments and their neurostructural correlates of abnormal neurodevelopment associated with IUGR

  16. Long-Term Functional Outcomes and Correlation with Regional Brain Connectivity by MRI Diffusion Tractography Metrics in a Near-Term Rabbit Model of Intrauterine Growth Restriction

    Science.gov (United States)

    Illa, Miriam; Eixarch, Elisenda; Batalle, Dafnis; Arbat-Plana, Ariadna; Muñoz-Moreno, Emma; Figueras, Francesc; Gratacos, Eduard

    2013-01-01

    Background Intrauterine growth restriction (IUGR) affects 5–10% of all newborns and is associated with increased risk of memory, attention and anxiety problems in late childhood and adolescence. The neurostructural correlates of long-term abnormal neurodevelopment associated with IUGR are unknown. Thus, the aim of this study was to provide a comprehensive description of the long-term functional and neurostructural correlates of abnormal neurodevelopment associated with IUGR in a near-term rabbit model (delivered at 30 days of gestation) and evaluate the development of quantitative imaging biomarkers of abnormal neurodevelopment based on diffusion magnetic resonance imaging (MRI) parameters and connectivity. Methodology At +70 postnatal days, 10 cases and 11 controls were functionally evaluated with the Open Field Behavioral Test which evaluates anxiety and attention and the Object Recognition Task that evaluates short-term memory and attention. Subsequently, brains were collected, fixed and a high resolution MRI was performed. Differences in diffusion parameters were analyzed by means of voxel-based and connectivity analysis measuring the number of fibers reconstructed within anxiety, attention and short-term memory networks over the total fibers. Principal Findings The results of the neurobehavioral and cognitive assessment showed a significant higher degree of anxiety, attention and memory problems in cases compared to controls in most of the variables explored. Voxel-based analysis (VBA) revealed significant differences between groups in multiple brain regions mainly in grey matter structures, whereas connectivity analysis demonstrated lower ratios of fibers within the networks in cases, reaching the statistical significance only in the left hemisphere for both networks. Finally, VBA and connectivity results were also correlated with functional outcome. Conclusions The rabbit model used reproduced long-term functional impairments and their neurostructural

  17. Development of an atmospheric diffusion numerical model for a nuclear facility. Numerical calculation method incorporating building effects

    International Nuclear Information System (INIS)

    Sada, Koichi; Michioka, Takenobu; Ichikawa, Yoichi

    2002-01-01

    Because effluent gas is sometimes released from low positions, viz., near the ground surface and around buildings, the effects caused by buildings within the site area are not negligible for gas diffusion predictions. For these reasons, the effects caused by buildings for gas diffusion are considered under the terrain following calculation coordinate system in this report. Numerical calculation meshes on the ground surface are treated as the building with the adaptation of wall function techniques of turbulent quantities in the flow calculations using a turbulence closure model. The reflection conditions of released particles on building surfaces are taken into consideration in the diffusion calculation using the Lagrangian particle model. Obtained flow and diffusion calculation results are compared with those of wind tunnel experiments around the building. It was apparent that features observed in a wind tunnel, viz., the formation of cavity regions behind the building and the gas diffusion to the ground surface behind the building, are also obtained by numerical calculation. (author)

  18. Annual and long-term prediction of the atmospheric corrosion of metals

    International Nuclear Information System (INIS)

    Morcillo, M.

    1998-01-01

    The atmospheric corrosion of metals is known to be a discontinuous electrochemical process which takes place only when the metallic surface is wet or moistened by different meteorological phenomena (rain, humidity condensation, fog, etc.) The magnitude of atmospheric corrosion would be relatively low if it were not for the presence of certain pollutants in the atmosphere, mainly sulphur dioxide (anthropogenic pollutant) and marine chlorides (natural pollutant). The literature contains different models for predicting the atmospheric metals over short periods (generally one year) and long periods (15, 20 or more years) of atmospheric exposure. In addition to the different meteorological factors (volume of precipitation, days of rain, relative humidity (RH), T, etc.), atmospheric SO 2 deposition rate and atmospheric salinity (Cl - ) appear as independent variables in all of these models. (Author)

  19. Long Term Monitoring of Atmospheric Composition at NOAA - Driving Science with 60 Year-old Records

    Science.gov (United States)

    Butler, J. H.

    2017-12-01

    NOAA's Global Monitoring Division and its precursor organizations have provided some of the longest real-time records of the trends and distributions of climatically relevant substances in the atmosphere, some going back for 60 years (http://www.esrl.noaa.gov/gmd). The focus of these measurements has been on obtaining reliable records of global trends and distributions of these substances, but the experimental design and use of measurements have advanced over time with evolving scientific questions. Today, and into this century, scientific questions continue to progress and the observing systems that address them will need to progress accordingly. Long-term, ground based observing systems in NOAA's Global Monitoring Division focus largely on three sets of questions, two of which align with WCRP grand challenges. These are Carbon Cycle System Feedbacks, Trends in Surface Radiation and Cloud Distributions, and Recovery of Stratospheric Ozone. The data collected and analyzed help us understand radiative forcing, climate sensitivity, air quality, climate modification, renewable energy options, and arctic processes, and they are useful for verifying model output and satellite retrievals. Regional information will become increasingly important for mitigating and adapting to climate change, and this information must be accurate, precise, and without bias. NOAA, with its long-standing networks and its role in providing calibrations for partnering organizations, is well positioned to provide the linkages necessary to assure that regional measurements are comparable. This presentation will identify major, climate-relevant findings that have come from NOAA's networks in the past and will address the long-term monitoring needs to support decision-making over coming decades as society begins to seriously address climate change.

  20. Effects of long-term low atmospheric pressure on gas exchange and growth of lettuce

    Science.gov (United States)

    Tang, Yongkang; Guo, Shuangsheng; Dong, Wenping; Qin, Lifeng; Ai, Weidang; Lin, Shan

    2010-09-01

    The objectives of this research were to determine photosynthesis, evapotranspiration and growth of lettuce at long-term low atmospheric pressure. Lettuce ( Lactuca sativa L . cv. Youmaicai) plants were grown at 40 kPa total pressure (8.4 kPa p) or 101 kPa total pressure (20.9 kPa p) from seed to harvest for 35 days. Germination rate of lettuce seeds decreased by 7.6% at low pressure, although this was not significant. There was no significant difference in crop photosynthetic rate between hypobaria and ambient pressure during the 35-day study. The crop evapotranspiration rate was significantly lower at low pressure than that at ambient pressure from 20 to 30 days after planting (DAP), but it had no significant difference before 20 DAP or after 30 DAP. The growth cycle of lettuce plants at low pressure was delayed. At low pressure, lettuce leaves were curly at the seedling stage and this disappeared gradually as the plants grew. Ambient lettuce plants were yellow and had an epinastic growth at harvest. The shoot height, leaf number, leaf length and shoot/root ratio were lower at low pressure than those at ambient pressure, while leaf area and root growth increased. Total biomass of lettuce plants grown at two pressures had no significant difference. Ethylene production at low pressure decreased significantly by 38.8% compared with ambient pressure. There was no significant difference in microelements, nutritional phytochemicals and nitrate concentrations at the two treatments. This research shows that lettuce can be grown at long-term low pressure (40 kPa) without significant adverse effects on seed germination, gas exchange and plant growth. Furthermore, ethylene release was reduced in hypobaria.

  1. CLIMATE CHANGE. Long-term climate forcing by atmospheric oxygen concentrations.

    Science.gov (United States)

    Poulsen, Christopher J; Tabor, Clay; White, Joseph D

    2015-06-12

    The percentage of oxygen in Earth's atmosphere varied between 10% and 35% throughout the Phanerozoic. These changes have been linked to the evolution, radiation, and size of animals but have not been considered to affect climate. We conducted simulations showing that modulation of the partial pressure of oxygen (pO2), as a result of its contribution to atmospheric mass and density, influences the optical depth of the atmosphere. Under low pO2 and a reduced-density atmosphere, shortwave scattering by air molecules and clouds is less frequent, leading to a substantial increase in surface shortwave forcing. Through feedbacks involving latent heat fluxes to the atmosphere and marine stratus clouds, surface shortwave forcing drives increases in atmospheric water vapor and global precipitation, enhances greenhouse forcing, and raises global surface temperature. Our results implicate pO2 as an important factor in climate forcing throughout geologic time. Copyright © 2015, American Association for the Advancement of Science.

  2. Markov branching diffusions: martingales, Girsanov type theorems and applications to the long term behaviour

    NARCIS (Netherlands)

    Engländer, J.; Kyprianou, A.E.

    2001-01-01

    Consider a spatial branching particle process where the underlying motion is a conservative diffusion on D C Rd corresponding to the elliptic op- erator L on D, and the branching is strictly binary (dyadic), with spatially varying rate ß(x) => 0 (and ß <> 0) which is assumed to be bounded

  3. Boundedness for a system of reaction-diffusion equations with more general Arrhenius term. Pt. 1

    International Nuclear Information System (INIS)

    Okoya, S.S.

    1992-11-01

    In this paper, we consider an extended model of a coupled nonlinear reaction-diffusion equation with Neumann-Neumann boundary conditions. We obtain upper linear growth bound for one of the components. We also find the corresponding bound for the case of Dirichlet-Dirichlet boundary conditions. (author). 12 refs

  4. Long-term solute diffusion in a granite block immersed in sea water

    International Nuclear Information System (INIS)

    Jefferies, N.L.

    1988-01-01

    Solute diffusion profiles for Cl - , Br - , F - and SO 4 -- have been measured in a granite block which was immersed in the sea at Falmouth, Cornwall, for 30 years. Leachable concentrations of Cl - and Br - were found to be higher in the block than in quarry samples of granite, which demonstrates that solutes from the sea water have diffused into the block. The Cl - and Br - profiles within the block were flat, implying that equilibrium has been reached between the seawater and granite porewater. The apparent diffusion coefficient and the solute accessible porosity have been estimated from these profiles, and these were used to calculate the intrinsic diffusion coefficient which was then compared with previously obtained laboratory data. Concentration profiles for F - and S0 4 -- indicate that these elements have high concentrations at the margins of the block (to depths of up to 15 cm) and are in the process of diffusing outwards into the surrounding seawater. The initially high porewater concentrations of F - and SO 4 -- in the block are believed to result from weathering of the granite prior to its immersion in the sea, due to the breakdown of primary minerals such as pyrite and the micas. F - and SO 4 -- sorptivity has been estimated from an analysis of the porewater concentration profiles. This preliminary experiment has demonstrated the potential for the measurement of solute migration in granite, as a result of the rock having been immersed in seawater. This work is part of the CEC project MIRAGE (radionuclide migration in the geosphere)- Second phase (1985-89) Research area 'Natural analogues'

  5. Mesoscale atmospheric modelling technology as a tool for the long-term meteorological dataset development

    Science.gov (United States)

    Platonov, Vladimir; Kislov, Alexander; Rivin, Gdaly; Varentsov, Mikhail; Rozinkina, Inna; Nikitin, Mikhail; Chumakov, Mikhail

    2017-04-01

    The detailed hydrodynamic modelling of meteorological parameters during the last 30 years (1985 - 2014) was performed for the Okhotsk Sea and the Sakhalin island regions. The regional non-hydrostatic atmospheric model COSMO-CLM used for this long-term simulation with 13.2, 6.6 and 2.2 km horizontal resolutions. The main objective of creation this dataset was the outlook of the investigation of statistical characteristics and the physical mechanisms of extreme weather events (primarily, wind speed extremes) on the small spatio-temporal scales. COSMO-CLM is the climate version of the well-known mesoscale COSMO model, including some modifications and extensions adapting to the long-term numerical experiments. The downscaling technique was realized and developed for the long-term simulations with three consequent nesting domains. ERA-Interim reanalysis ( 0.75 degrees resolution) used as global forcing data for the starting domain ( 13.2 km horizontal resolution), then these simulation data used as initial and boundary conditions for the next model runs over the domain with 6.6 km resolution, and similarly, for the next step to 2.2 km domain. Besides, the COSMO-CLM model configuration for 13.2 km run included the spectral nudging technique, i.e. an additional assimilation of reanalysis data not only at boundaries, but also inside the whole domain. Practically, this computational scheme realized on the SGI Altix 4700 supercomputer system in the Main Computer Center of Roshydromet and used 2,400 hours of CPU time total. According to modelling results, the verification of the obtained dataset was performed on the observation data. Estimations showed the mean error -0.5 0C, up to 2 - 3 0C RMSE in temperature, and overestimation in wind speed (RMSE is up to 2 m/s). Overall, analysis showed that the used downscaling technique with applying the COSMO-CLM model reproduced the meteorological conditions, spatial distribution, seasonal and synoptic variability of temperature and

  6. Long-term global distribution of earth's shortwave radiation budget at the top of atmosphere

    Directory of Open Access Journals (Sweden)

    N. Hatzianastassiou

    2004-01-01

    Full Text Available The mean monthly shortwave (SW radiation budget at the top of atmosphere (TOA was computed on 2.5° longitude-latitude resolution for the 14-year period from 1984 to 1997, using a radiative transfer model with long-term climatological data from the International Satellite Cloud Climatology Project (ISCCP-D2 supplemented by data from the National Centers for Environmental Prediction – National Center for Atmospheric Research (NCEP-NCAR Global Reanalysis project, and other global data bases such as TIROS Operational Vertical Sounder (TOVS and Global Aerosol Data Set (GADS. The model radiative fluxes at TOA were validated against Earth Radiation Budget Experiment (ERBE S4 scanner satellite data (1985–1989. The model is able to predict the seasonal and geographical variation of SW TOA fluxes. On a mean annual and global basis, the model is in very good agreement with ERBE, overestimating the outgoing SW radiation at TOA (OSR by 0.93 Wm-2 (or by 0.92%, within the ERBE uncertainties. At pixel level, the OSR differences between model and ERBE are mostly within ±10 Wm-2, with ±5 Wm-2 over extended regions, while there exist some geographic areas with differences of up to 40 Wm-2, associated with uncertainties in cloud properties and surface albedo. The 14-year average model results give a planetary albedo equal to 29.6% and a TOA OSR flux of 101.2 Wm-2. A significant linearly decreasing trend in OSR and planetary albedo was found, equal to 2.3 Wm-2 and 0.6% (in absolute values, respectively, over the 14-year period (from January 1984 to December 1997, indicating an increasing solar planetary warming. This planetary SW radiative heating occurs in the tropical and sub-tropical areas (20° S–20° N, with clouds being the most likely cause. The computed global mean OSR anomaly ranges within ±4 Wm-2, with signals from El Niño and La Niña events or Pinatubo eruption, whereas significant negative OSR anomalies, starting from year 1992, are also

  7. Understanding Atmospheric Behaviour in Terms of Entropy: A Review of Applications of the Second Law of Thermodynamics to Meteorology

    Directory of Open Access Journals (Sweden)

    Donghai Wang

    2011-01-01

    Full Text Available The concept of entropy and its relevant principles, mainly the principle of maximum entropy production (MEP, the effect of negative entropy flow (NEF on the organization of atmospheric systems and the principle of the Second Law of thermodynamics, as well as their applications to atmospheric sciences, are reviewed. Some formulations of sub-grid processes such as diffusion parameterization schemes in computational geophysical fluid dynamics that can be improved based on full-irreversibility are also discussed, although they have not yet been systematically subjected to scrutiny from the perspective of the entropy budgets. A comparative investigation shows that the principle of MEP applies to the entropy production of macroscopic fluxes and determines the most probable state, that is, a system may choose a development meta-stable trajectory with a smaller production since entropy production behavior involves many specific dynamical and thermodynamic processes in the atmosphere and the extremal principles only provide a general insight into the overall configuration of the atmosphere. In contrast to the principle of MEP, the analysis of NEF is able to provide a new insight into the mechanism responsible for the evolution of a weather system as well as a new approach to predicting its track and intensity trend.

  8. Short-term diffusive sampler for nitrogen dioxide monitoring in epidemiology

    International Nuclear Information System (INIS)

    Michaud, J.P.; Quackenboss, J.

    1991-01-01

    An automated timed exposure diffusive sampler (TEDS) for sampling nitrogen dioxide (NO 2 ) was developed for use in epidemiological studies. The TEDS sequentially exposes four passive sampling devices (PSD) by microprocessor controlled valves while a pump and air flow guide prevent sampler starvation. Two TEDS units and two portable, real-time NO 2 monitors were tested for accuracy, precision, sensitivity, and linearity of response. The accuracy of the TEDS was within 10 percent of the means of the measured values. The TEDS sensitivity was 20 to 30 ppb-hour for NO 2 . Co-location of the TEDS with a chemiluminescent NO x monitor (EPA reference method) showed a similar responses to ambient NO 2 . TEDS allows better time resolution than traditional diffusive samplers (i.e., Palmes tube) while sharing their ability to sample a variety of gases

  9. Studies on tritium incorporation into wheat plants after short-term exposure to atmospheric tritium

    International Nuclear Information System (INIS)

    Diabate, S.; Strack, S.; Raskob, W.

    1996-01-01

    The paper summarizes the results of a series of laboratory experiments to study the uptake, loss, conversion and translocation of tritium in wheat plants following a short-term exposure to atmospheric tritiated water vapour (HTO) under laboratory conditions. The experiments were accompanied by the development of a Plant-OBT-Model to calculate the tritium behaviour in wheat. Exposures of potted plants were carried out between anthesis and maturity, under day conditions at two different light intensities (900 μmol m -2 s -1 and 120 μmol m -2 s -1 photosynthetic active radiation) and under night conditions. In leaves, the tritium uptake into tissue water tritium (TWT) was about four times lower under night conditions than day conditions. Organically bound tritium (OBT) was generated in leaves, stems and ears under day as well as under night conditions. The initial relative OBT concentrations in leaves observed under night conditions were about 50% of those under day conditions. OBT was translocated into the grain in dependence on the growth rate of the grain. Due to incorporation of new organic matter with lower OBT concentration into the grain, the specific OBT concentrations decreased slightly until harvest but the total OBT was rather constant. Once translocation to grain has taken place, OBT is lost only slowly. The growth of the plants has been calibrated with the measured growth data of winter wheat and spring wheat. Subsequently, the tritium incorporation was calibrated using the results of the exposure experiments in the same year. The final OBT concentration in the grain can be predicted with sufficient precision. However, the modelling of the OBT formation and turnover processes right after exposure to tritium needs improvement. A comprehensive validation of the model with independent data sets is still necessary. (J.P.N.)

  10. Long term evolution of temperature in the venus upper atmosphere at the evening and morning terminators

    Science.gov (United States)

    Krause, P.; Sornig, M.; Wischnewski, C.; Kostiuk, T.; Livengood, T. A.; Herrmann, M.; Sonnabend, G.; Stangier, T.; Wiegand, M.; Pätzold, M.; Mahieux, A.; Vandaele, A. C.; Piccialli, A.; Montmessin, F.

    2018-01-01

    within a single run with a typically time range of 2-10 days. This variation is not connected to the solar cycle. Sub-millimeter observations by Clancy et al. found a relation between temperatures and long-term variation in mesospheric water vapor, SO2, and sulfate aerosols (Clancy and Muhleman, 1991; Clancy et al., 2012). SO2 column densities observed by SOIR at the terminator are fairly stable over the time period of 2006-2011 (Mahieux et al., 2015), supporting the hypothesis of a relation between SO2 and temperature variations. The temperatures derived from the infrared heterodyne spectroscopy (IR-het) are compared to results from the Venus Express space mission (VEx). A consistence with the temperatures from the VEx instruments SOIR, VIRTIS and SPICAV is found. As the instruments probe different local time, SPICAV probes the pure nightside, SOIR across the terminator and IR-het the pure dayside atmosphere it is not surprising that the IR-het temperatures are mostly on the warmer side compared to results from SPICAV and SOIR.

  11. The use of nonlinear regression analysis for integrating pollutant concentration measurements with atmospheric dispersion modeling for source term estimation

    International Nuclear Information System (INIS)

    Edwards, L.L.; Freis, R.P.; Peters, L.G.; Gudiksen, P.H.; Pitovranov, S.E.

    1993-01-01

    The accuracy associated with assessing the environmental consequences of an accidental release of radioactivity is highly dependent on the knowledge of the source term characteristics, which are generally poorly known. The development of an automated numerical technique that integrates the radiological measurements with atmospheric dispersion modeling for more accurate source term estimation is reported. Often, this process of parameter estimation is performed by an emergency response assessor, who takes an intelligent first guess at the model parameters, then, comparing the model results with whatever measurements are available, makes an intuitive, informed next guess of the model parameters. This process may be repeated any number of times until the assessor feels that the model results are reasonable in terms of the measured observations. A new approach, based on a nonlinear least-squares regression scheme coupled with the existing Atmospheric Release Advisory Capability three-dimensional atmospheric dispersion models, is to supplement the assessor's intuition with automated mathematical methods that do not significantly increase the response time of the existing predictive models. The viability of the approach is evaluated by estimation of the known SF 6 tracer release rates associated with the Mesoscale Atmospheric Transport Studies tracer experiments conducted at the Savannah River Laboratory during 1983. These 19 experiments resulted in 14 successful, separate tracer releases with sampling of the tracer plumes along the cross-plume arc situated ∼30 km from the release site

  12. Long-Term Simulated Atmospheric Nitrogen Deposition Alters Leaf and Fine Root Decomposition

    Science.gov (United States)

    Atmospheric nitrogen deposition has been suggested to increase forest carbon sequestration across much of the Northern Hemisphere; slower organic matter decomposition could contribute to this increase. At four sugar maple (Acer saccharum)-dominated northern hardwood forests, we p...

  13. Long-term decline of global atmospheric ethane concentrations and implications for methane.

    Science.gov (United States)

    Simpson, Isobel J; Sulbaek Andersen, Mads P; Meinardi, Simone; Bruhwiler, Lori; Blake, Nicola J; Helmig, Detlev; Rowland, F Sherwood; Blake, Donald R

    2012-08-23

    After methane, ethane is the most abundant hydrocarbon in the remote atmosphere. It is a precursor to tropospheric ozone and it influences the atmosphere's oxidative capacity through its reaction with the hydroxyl radical, ethane's primary atmospheric sink. Here we present the longest continuous record of global atmospheric ethane levels. We show that global ethane emission rates decreased from 14.3 to 11.3 teragrams per year, or by 21 per cent, from 1984 to 2010. We attribute this to decreasing fugitive emissions from ethane's fossil fuel source--most probably decreased venting and flaring of natural gas in oil fields--rather than a decline in its other major sources, biofuel use and biomass burning. Ethane's major emission sources are shared with methane, and recent studies have disagreed on whether reduced fossil fuel or microbial emissions have caused methane's atmospheric growth rate to slow. Our findings suggest that reduced fugitive fossil fuel emissions account for at least 10-21 teragrams per year (30-70 per cent) of the decrease in methane's global emissions, significantly contributing to methane's slowing atmospheric growth rate since the mid-1980s.

  14. The effect of diffusivity on gas-liquid mass transfer in stirred vessels. Experiments at atmospheric and elevated pressures

    NARCIS (Netherlands)

    Versteeg, G.F.; Blauwhoff, P.M.M.; Swaaij, W.P.M. van

    1987-01-01

    Mass transfer has been studied in gas-liquid stirred vessels with horizontal interfaces which appeared to the eye to be completely smooth. Special attention has been paid to the influence of the coefficient of molecular diffusion. The results are compared with those published before. The simplifying

  15. Exponential Stability for Impulsive BAM Neural Networks with Time-Varying Delays and Reaction-Diffusion Terms

    Directory of Open Access Journals (Sweden)

    Qiankun Song

    2007-06-01

    Full Text Available Impulsive bidirectional associative memory neural network model with time-varying delays and reaction-diffusion terms is considered. Several sufficient conditions ensuring the existence, uniqueness, and global exponential stability of equilibrium point for the addressed neural network are derived by M-matrix theory, analytic methods, and inequality techniques. Moreover, the exponential convergence rate index is estimated, which depends on the system parameters. The obtained results in this paper are less restrictive than previously known criteria. Two examples are given to show the effectiveness of the obtained results.

  16. Exponential Stability for Impulsive BAM Neural Networks with Time-Varying Delays and Reaction-Diffusion Terms

    Directory of Open Access Journals (Sweden)

    Cao Jinde

    2007-01-01

    Full Text Available Impulsive bidirectional associative memory neural network model with time-varying delays and reaction-diffusion terms is considered. Several sufficient conditions ensuring the existence, uniqueness, and global exponential stability of equilibrium point for the addressed neural network are derived by M-matrix theory, analytic methods, and inequality techniques. Moreover, the exponential convergence rate index is estimated, which depends on the system parameters. The obtained results in this paper are less restrictive than previously known criteria. Two examples are given to show the effectiveness of the obtained results.

  17. Initial-boundary value problems for multi-term time-fractional diffusion equations with x-dependent coefficients

    OpenAIRE

    Li, Zhiyuan; Huang, Xinchi; Yamamoto, Masahiro

    2018-01-01

    In this paper, we discuss an initial-boundary value problem (IBVP) for the multi-term time-fractional diffusion equation with x-dependent coefficients. By means of the Mittag-Leffler functions and the eigenfunction expansion, we reduce the IBVP to an equivalent integral equation to show the unique existence and the analyticity of the solution for the equation. Especially, in the case where all the coefficients of the time-fractional derivatives are non-negative, by the Laplace and inversion L...

  18. Change-point analysis data of neonatal diffusion tensor MRI in preterm and term-born infants

    Directory of Open Access Journals (Sweden)

    Dan Wu

    2017-06-01

    Full Text Available The data presented in this article are related to the research article entitled “Mapping the Critical Gestational Age at Birth that Alters Brain Development in Preterm-born Infants using Multi-Modal MRI” (Wu et al., 2017 [1]. Brain immaturity at birth poses critical neurological risks in the preterm-born infants. We used a novel change-point model to analyze the critical gestational age at birth (GAB that could affect postnatal development, based on diffusion tensor MRI (DTI acquired from 43 preterm and 43 term-born infants in 126 brain regions. In the corresponding research article, we presented change-point analysis of fractional anisotropy (FA and mean diffusivities (MD measurements in these infants. In this article, we offered the relative changes of axonal and radial diffusivities (AD and RD in relation to the change of FA and FA-based change-points, and we also provided the AD- and RD-based change-point results.

  19. Brain changes in long-term zen meditators using proton magnetic resonance spectroscopy and diffusion tensor imaging: a controlled study.

    Directory of Open Access Journals (Sweden)

    Nicolás Fayed

    Full Text Available INTRODUCTION: This work aimed to determine whether (1H magnetic resonance imaging (MRI, magnetic resonance spectroscopy (MRS, diffusion-weighted imaging (DWI and diffusion tensor imaging (DTI are correlated with years of meditation and psychological variables in long-term Zen meditators compared to healthy non-meditator controls. MATERIALS AND METHODS: Design. Controlled, cross-sectional study. Sample. Meditators were recruited from a Zen Buddhist monastery. The control group was recruited from hospital staff. Meditators were administered questionnaires on anxiety, depression, cognitive impairment and mindfulness. (1H-MRS (1.5 T of the brain was carried out by exploring four areas: both thalami, both hippocampi, the posterior superior parietal lobule (PSPL and posterior cingulate gyrus. Predefined areas of the brain were measured for diffusivity (ADC and fractional anisotropy (FA by MR-DTI. RESULTS: Myo-inositol (mI was increased in the posterior cingulate gyrus and Glutamate (Glu, N-acetyl-aspartate (NAA and N-acetyl-aspartate/Creatine (NAA/Cr was reduced in the left thalamus in meditators. We found a significant positive correlation between mI in the posterior cingulate and years of meditation (r = 0.518; p = .019. We also found significant negative correlations between Glu (r = -0.452; p = .045, NAA (r = -0.617; p = .003 and NAA/Cr (r = -0.448; P = .047 in the left thalamus and years of meditation. Meditators showed a lower Apparent Diffusion Coefficient (ADC in the left posterior parietal white matter than did controls, and the ADC was negatively correlated with years of meditation (r = -0.4850, p = .0066. CONCLUSIONS: The results are consistent with the view that mI, Glu and NAA are the most important altered metabolites. This study provides evidence of subtle abnormalities in neuronal function in regions of the white matter in meditators.

  20. The impact of changes in parameterizations of surface drag and vertical diffusion on the large-scale circulation in the Community Atmosphere Model (CAM5)

    Science.gov (United States)

    Lindvall, Jenny; Svensson, Gunilla; Caballero, Rodrigo

    2017-06-01

    Simulations with the Community Atmosphere Model version 5 (CAM5) are used to analyze the sensitivity of the large-scale circulation to changes in parameterizations of orographic surface drag and vertical diffusion. Many GCMs and NWP models use enhanced turbulent mixing in stable conditions to improve simulations, while CAM5 cuts off all turbulence at high stabilities and instead employs a strong orographic surface stress parameterization, known as turbulent mountain stress (TMS). TMS completely dominates the surface stress over land and reduces the near-surface wind speeds compared to simulations without TMS. It is found that TMS is generally beneficial for the large-scale circulation as it improves zonal wind speeds, Arctic sea level pressure and zonal anomalies of the 500-hPa stream function, compared to ERA-Interim. It also alleviates atmospheric blocking frequency biases in the Northern Hemisphere. Using a scheme that instead allows for a modest increase of turbulent diffusion at higher stabilities only in the planetary boundary layer (PBL) appears to in some aspects have a similar, although much smaller, beneficial effect as TMS. Enhanced mixing throughout the atmospheric column, however, degrades the CAM5 simulation. Evaluating the simulations in comparison with detailed measurements at two locations reveals that TMS is detrimental for the PBL at the flat grassland ARM Southern Great Plains site, giving too strong wind turning and too deep PBLs. At the Sodankylä forest site, the effect of TMS is smaller due to the larger local vegetation roughness. At both sites, all simulations substantially overestimate the boundary layer ageostrophic flow.

  1. On the role of solar and geomagnetic activity in long-term trends in the atmosphere-ionosphere system

    Czech Academy of Sciences Publication Activity Database

    Laštovička, Jan

    2005-01-01

    Roč. 67, č. 1-2 (2005), s. 83-92 ISSN 1364-6826 R&D Projects: GA AV ČR KSK3012103; GA AV ČR IAA3042102 Institutional research plan: CEZ:AV0Z30420517 Keywords : Long-term trends * Atmosphere * Ionosphere * Solar activity * Geomagnetic activity Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 1.309, year: 2005

  2. Long-term decomposition of grass roots as affected by elevated atmospheric carbon dioxide

    NARCIS (Netherlands)

    Ginkel, van J.H.; Gorissen, A.; Veen, van J.A.

    1996-01-01

    Carbon input into the soil and decomposition processes under elevated CO2 are highly relevant for C sequestering in the soil. Plant growth and decomposition of root material under ambient and elevated atmospheric CO2 concentrations were monitored in wind tunnels. Grass roots (Lolium perenne L.) were

  3. Comparisons of carotid artery stenting and carotid endoarterectomy in terms of diffusion-weighted MR imaging

    International Nuclear Information System (INIS)

    Mitsuoka, Hiroshi; Shintani, Tsunehiro; Masuda, Mikio; Higashi, Shigeki

    2009-01-01

    The objective of this study was to compare two methods of treatment for carotid arterial stenosis, carotid endarterectomy (CEA) and carotid artery stenting (CAS), by means of diffusion-weighted MR imaging (DWI). Nineteen treatments in 18 cases during the 2007 academic year were included in this study. CAS was performed for 9 cases with 10 lesions (10 procedures), while 9 cases with 9 lesions (9 procedures) were treated by CEA. Patients were examined by a neurologist before and after the procedure, and had pre- and post-procedural DWI. No strokes or transient ischemic attacks (TIAs) were observed in these cases. New DWI lesions were found in 7 out of the 10 procedures of CAS imaged 24 hours postprocedure, (average: 2.0 lesions). No new lesions were detected on DWI of CEA cases (χ 2 =8.33, p=0.0039). Certain high-risk subsets may respond well to CAS with a very low incidence of clinically-evident neurologic events, but with significantly higher incidence of periprocedural micro-brain embolism. Currently, CEA should be the first choice of treatment for atherosclerotic carotid artery stenosis. (author)

  4. Parameterized source term in the diffusion approximation for enhanced near-field modeling of collimated light

    Science.gov (United States)

    Jia, Mengyu; Wang, Shuang; Chen, Xueying; Gao, Feng; Zhao, Huijuan

    2016-03-01

    Most analytical methods for describing light propagation in turbid medium exhibit low effectiveness in the near-field of a collimated source. Motivated by the Charge Simulation Method in electromagnetic theory as well as the established discrete source based modeling, we have reported on an improved explicit model, referred to as "Virtual Source" (VS) diffuse approximation (DA), to inherit the mathematical simplicity of the DA while considerably extend its validity in modeling the near-field photon migration in low-albedo medium. In this model, the collimated light in the standard DA is analogously approximated as multiple isotropic point sources (VS) distributed along the incident direction. For performance enhancement, a fitting procedure between the calculated and realistic reflectances is adopted in the nearfield to optimize the VS parameters (intensities and locations). To be practically applicable, an explicit 2VS-DA model is established based on close-form derivations of the VS parameters for the typical ranges of the optical parameters. The proposed VS-DA model is validated by comparing with the Monte Carlo simulations, and further introduced in the image reconstruction of the Laminar Optical Tomography system.

  5. Short-term cyclic variations and diurnal variations of the Venus upper atmosphere

    Science.gov (United States)

    Keating, G. M.; Taylor, F. W.; Nicholson, J. Y.; Hinson, E. W.

    1979-01-01

    The vertical structure of the nighttime thermosphere and exosphere of Venus was discussed. A comparison of the day and nighttime profiles indicates, contrary to the model of Dickinson and Riley (1977), that densities (principally atomic oxygen) dropped sharply from day to night. It was suggested either that the lower estimates were related to cooler exospheric temperatures at night or that the atomic bulge was flatter than expected at lower altitudes. Large periodic oscillations, in both density and inferred exospheric temperatures, were detected with periods of 5 to 6 days. The possibility that cyclic variations in the thermosphere and stratosphere were caused by planetary-scale waves, propagated upward from the lower atmosphere, was investigated using simultaneous temperature measurements obtained by the Venus radiometric temperature experiment (VORTEX). Inferred exospheric temperatures in the morning were found to be lower than in the evening as if the atmosphere rotated in the direction of the planet's rotation, similar to that of earth. Superrotation of the thermosphere and exosphere was discussed as a possible extension of the 4-day cyclic atmospheric rotation near the cloud tops.

  6. Gaussian Plume Model Parameters for Ground-Level and Elevated Sources Derived from the Atmospheric Diffusion Equation in the Neutral and Stable Conditions

    International Nuclear Information System (INIS)

    Essa, K.S.M.

    2009-01-01

    The analytical solution of the atmospheric diffusion equation for a point source gives the ground-level concentration profiles. It depends on the wind speed ua nd vertical dispersion coefficient σ z expressed by Pasquill power laws. Both σ z and u are functions of downwind distance, stability and source elevation, while for the ground-level emission u is constant. In the neutral and stable conditions, the Gaussian plume model and finite difference numerical methods with wind speed in power law and the vertical dispersion coefficient in exponential law are estimated. This work shows that the estimated ground-level concentrations of the Gaussian model for high-level source and numerical finite difference method are very match fit to the observed ground-level concentrations of the Gaussian model

  7. On the formation mechanisms of the diffuse atmospheric pressure dielectric barrier discharge in CVD processes of thin silica-like films

    International Nuclear Information System (INIS)

    Starostin, S A; Premkumar, P Antony; Creatore, M; Van Veldhuizen, E M; Van de Sanden, M C M; De Vries, H; Paffen, R M J

    2009-01-01

    Pathways of formation and temporal evolution of the diffuse dielectric barrier discharge at atmospheric pressure were experimentally studied in this work by means of optical (fast imaging camera) and electrical diagnostics. The chosen model system is relevant for applications of plasma-enhanced chemical vapor deposition of thin silica-like film on the polymeric substrate, from cost-efficient gas mixtures of Ar/N 2 /O 2 /hexamethyldisiloxane. It was found that the discharge can gradually experience the phases of homogeneous low current Townsend-like mode, local Townsend to glow transition and expanding high current density (∼0.7 A cm -2 ) glow-like mode. While the glow-like current spot occupies momentarily only a small part of the electrode area, its expanding behavior provides uniform treatment of the whole substrate surface. Alternatively, it was observed that a visually uniform discharge can be formed by the numerous microdischarges overlapping over the large electrode area.

  8. Long-term performance of activated carbon air cathodes with different diffusion layer porosities in microbial fuel cells

    KAUST Repository

    Zhang, Fang

    2011-08-01

    Activated carbon (AC) air-cathodes are inexpensive and useful alternatives to Pt-catalyzed electrodes in microbial fuel cells (MFCs), but information is needed on their long-term stability for oxygen reduction. AC cathodes were constructed with diffusion layers (DLs) with two different porosities (30% and 70%) to evaluate the effects of increased oxygen transfer on power. The 70% DL cathode initially produced a maximum power density of 1214±123mW/m 2 (cathode projected surface area; 35±4W/m 3 based on liquid volume), but it decreased by 40% after 1 year to 734±18mW/m 2. The 30% DL cathode initially produced less power than the 70% DL cathode, but it only decreased by 22% after 1 year (from 1014±2mW/m 2 to 789±68mW/m 2). Electrochemical tests were used to examine the reasons for the degraded performance. Diffusion resistance in the cathode was found to be the primary component of the internal resistance, and it increased over time. Replacing the cathode after 1 year completely restored the original power densities. These results suggest that the degradation in cathode performance was due to clogging of the AC micropores. These findings show that AC is a cost-effective material for oxygen reduction that can still produce ~750mW/m 2 after 1 year. © 2011 Elsevier B.V.

  9. Can climate sensitivity be estimated from short-term relationships of top-of-atmosphere net radiation and surface temperature?

    International Nuclear Information System (INIS)

    Lin Bing; Min Qilong; Sun Wenbo; Hu Yongxiang; Fan, Tai-Fang

    2011-01-01

    Increasing the knowledge in climate radiative feedbacks is critical for current climate studies. This work focuses on short-term relationships between global mean surface temperature and top-of-atmosphere (TOA) net radiation. The relationships may be used to characterize the climate feedback as suggested by some recent studies. As those recent studies, an energy balance model with ocean mixed layer and both radiative and non-radiative heat sources is used here. The significant improvement of current model is that climate system memories are considered. Based on model simulations, short-term relationship between global mean surface temperature and TOA net radiation (or the linear striation feature as suggested by previous studies) might represent climate feedbacks when the system had no memories. However, climate systems with the same short-term feedbacks but different memories would have a similar linear striation feature. This linear striation feature reflects only fast components of climate feedbacks and may not represent the total climate feedback even when the memory length of climate systems is minimal. The potential errors in the use of short-term relationships in estimations of climate sensitivity could be big. In short time scales, fast climate processes may overwhelm long-term climate feedbacks. Thus, the climate radiative feedback parameter obtained from short-term data may not provide a reliable estimate of climate sensitivity. This result also suggests that long-term observations of global surface temperature and TOA radiation are critical in the understanding of climate feedbacks and sensitivities.

  10. Conservative diffusions

    International Nuclear Information System (INIS)

    Carlen, E.A.

    1984-01-01

    In Nelson's stochastic mechanics, quantum phenomena are described in terms of diffusions instead of wave functions. These diffusions are formally given by stochastic differential equations with extremely singular coefficients. Using PDE methods, we prove the existence of solutions. This reult provides a rigorous basis for stochastic mechanics. (orig.)

  11. Brain Changes in Long-Term Zen Meditators Using Proton Magnetic Resonance Spectroscopy and Diffusion Tensor Imaging: A Controlled Study

    Science.gov (United States)

    Fayed, Nicolás; Lopez del Hoyo, Yolanda; Andres, Eva; Serrano-Blanco, Antoni; Bellón, Juan; Aguilar, Keyla; Cebolla, Ausias; Garcia-Campayo, Javier

    2013-01-01

    Introduction This work aimed to determine whether 1H magnetic resonance imaging (MRI), magnetic resonance spectroscopy (MRS), diffusion-weighted imaging (DWI) and diffusion tensor imaging (DTI) are correlated with years of meditation and psychological variables in long-term Zen meditators compared to healthy non-meditator controls. Materials and Methods Design. Controlled, cross-sectional study. Sample. Meditators were recruited from a Zen Buddhist monastery. The control group was recruited from hospital staff. Meditators were administered questionnaires on anxiety, depression, cognitive impairment and mindfulness. 1H-MRS (1.5 T) of the brain was carried out by exploring four areas: both thalami, both hippocampi, the posterior superior parietal lobule (PSPL) and posterior cingulate gyrus. Predefined areas of the brain were measured for diffusivity (ADC) and fractional anisotropy (FA) by MR-DTI. Results Myo-inositol (mI) was increased in the posterior cingulate gyrus and Glutamate (Glu), N-acetyl-aspartate (NAA) and N-acetyl-aspartate/Creatine (NAA/Cr) was reduced in the left thalamus in meditators. We found a significant positive correlation between mI in the posterior cingulate and years of meditation (r = 0.518; p = .019). We also found significant negative correlations between Glu (r = −0.452; p = .045), NAA (r = −0.617; p = .003) and NAA/Cr (r = −0.448; P = .047) in the left thalamus and years of meditation. Meditators showed a lower Apparent Diffusion Coefficient (ADC) in the left posterior parietal white matter than did controls, and the ADC was negatively correlated with years of meditation (r = −0.4850, p = .0066). Conclusions The results are consistent with the view that mI, Glu and NAA are the most important altered metabolites. This study provides evidence of subtle abnormalities in neuronal function in regions of the white matter in meditators. PMID:23536796

  12. Evaluation for the models of neutron diffusion theory in terms of power density distributions of the HTTR

    International Nuclear Information System (INIS)

    Takamatsu, Kuniyoshi; Shimakawa, Satoshi; Nojiri, Naoki; Fujimoto, Nozomu

    2003-10-01

    In the case of evaluations for the highest temperature of the fuels in the HTTR, it is very important to expect the power density distributions accurately; therefore, it is necessary to improve the analytical model with the neutron diffusion and the burn-up theory. The power density distributions are analyzed in terms of two models, the one mixing the fuels and the burnable poisons homogeneously and the other modeling them heterogeneously. Moreover these analytical power density distributions are compared with the ones derived from the gross gamma-ray measurements and the Monte Carlo calculational code with continuous energy. As a result the homogeneous mixed model isn't enough to expect the power density distributions of the core in the axial direction; on the other hand, the heterogeneous model improves the accuracy. (author)

  13. Local scale atmospheric diffusion at a coastal site in the presence of breeze effect (Phase I and II: data collection at a coastal site and off shore)

    International Nuclear Information System (INIS)

    Cagnetti, P.; Ferrara, V.; Pellegrini, A.

    1985-01-01

    The aim of this contract is the characterization, from the thermal and anemological point of view of the lower layers of the atmosphere at a coastal site, affected by breeze circulation. Data are utilized to set up diffusion models for accidental releases of airborne materials, both of short and prolonged duration. Five inland meteorological campaigns, starting from Jan. 82 (Jan., Apr., Jul., Oct. 1982, Jan. 1983), have been carried out; an appropriate extension of the contract allowed the execution of two more campaigns in the open sea (Apr., Jul. 1983), utilizing the oceanographic ship ''Bannock'' kindly supplied by CNR. The analysis of the data showed the development of a well defined IBL during on-shore flow only in Spring and Summer, while an inversion layer was detectable aloft independently of the season (provided that an anticyclonic situation was present). According to those relevant features a simple diffusion model has been developed for short duration releases at local scale. Finally, the analysis and elaboration of the data, collected on site by a meteorological automatic station, allowed the extension of the model to prolonged releases

  14. Local scale atmospheric diffusion at a coastal site in the presence of breeze effect (phase III: data elaboration and model development). Volume 1

    International Nuclear Information System (INIS)

    Cagnetti, P.; Ferrara, V.; Pellegrini, A.

    1985-01-01

    The aim of this contract is the characterization, from the thermal and anemological point of view, of the lower layers of the atmosphere at a coastal site, affected by breeze circulation. Data are utilized to set up diffusion models for accidental releases of airborne materials, both of short and prolonged duration. Five inland meteorological campaigns, starting from Jan. 82 (Jan., Apr., Jul., Oct. 1982, Jan. 1983), have been carried out; an appropriate extension of the contract allowed the execution of two more campaigns in the open sea (Apr., Jul. 1983), utilizing the oceanographic ship ''Bannock'' kindly supplied by CNR. The analysis of the data showed the development of a well defined IBL during on-shore flow only in Spring and Summer, while an inversion layer was detectable aloft independently of the season (provided that an anticyclonic situation was present). According to those relevant features a simple diffusion model has been developed for short duration releases at local scale. Finally, the analysis and elaboration of the data, collected on site by a meteorological automatic station, allowed the extension of the model to prolonged releases

  15. Probabilistic diffusion tractography of the optic radiations and visual function in preterm infants at term equivalent age.

    Science.gov (United States)

    Bassi, Laura; Ricci, Daniela; Volzone, Anna; Allsop, Joanna M; Srinivasan, Latha; Pai, Aakash; Ribes, Carmen; Ramenghi, Luca A; Mercuri, Eugenio; Mosca, Fabio; Edwards, A David; Cowan, Frances M; Rutherford, Mary A; Counsell, Serena J

    2008-02-01

    Children born prematurely have a high incidence of visual disorders which cannot always be explained by focal retinal or brain lesions. The aim of this study was to test the hypothesis that visual function in preterm infants is related to the microstructural development of white matter in the optic radiations. We used diffusion tensor imaging (DTI) with probabilistic diffusion tractography to delineate the optic radiations at term equivalent age and compared the fractional anisotropy (FA) to a contemporaneous evaluation of visual function. Thirty-seven preterm infants (19 male) born at median (range) 28(+4) (24(+1)-32(+3)) weeks gestational age, were examined at a post-menstrual age of 42 (39(+6)-43) weeks. MRI and DTI were acquired on a 3 Tesla MR system with DTI obtained in 15 non-collinear directions with a b value of 750 s/mm(2). Tracts were generated from a seed mask placed in the white matter lateral to the lateral geniculate nucleus and mean FA values of these tracts were determined. Visual assessment was performed using a battery of nine items assessing different aspects of visual abilities. Ten infants had evidence of cerebral lesions on conventional MRI. Multiple regression analysis demonstrated that the visual assessment score was independently correlated with FA values, but not gestational age at birth, post-menstrual age at scan or the presence of lesions on conventional MRI. The occurrence of mild retinopathy of prematurity did not affect the FA measures or visual scores. We then performed a secondary analysis using tract-based spatial statistics to determine whether global brain white matter development was related to visual function and found that only FA in the optic radiations was correlated with visual assessment score. Our results suggest that in preterm infants at term equivalent age visual function is directly related to the development of white matter in the optic radiations.

  16. Long Term Sorption Diffusion Experiment (LTDE-SD). Performance of main in situ experiment and results from water phase measurements

    International Nuclear Information System (INIS)

    Widestrand, Henrik; Byegaard, Johan; Nilsson, Kersti; Hoeglund, Susanne; Gustafsson, Erik; Kronberg, Magnus

    2010-12-01

    The LTDE-SD experiment, (Long Term Sorption Diffusion Experiment) aimed at increasing the scientific knowledge of sorption and diffusion under in situ conditions and to provide data for performance and safety assessment calculations. Performance and results of the in situ experiment phase are presented in the report. In total, 21 radionuclide trace elements and one stable trace element were injected, circulated and sampled for ∼6.5 months in a closed borehole section. The trace elements represented non-sorbing tracers and sorbing tracers for which the sorption was dominated by a cation exchange mechanism, a surface complexation mechanism, or dependent on an electrochemical reduction in order to reach the tetravalent state (oxidation state IV) considered very strongly sorbing. The borehole section in contact with the tracer labelled groundwater consisted in part of a natural fracture surface and a borehole section in the unaltered matrix rock, devoid of natural fractures. Water samples were regularly extracted and analysed for trace element concentration and a few ion exchange speciation and filtered samplings were also conducted. Independent colloid filtering and chemical speciation calculations were performed in support the evaluation. Sorption was demonstrated for a series of elements present in the experiment. The amounts lost of the different respective tracers from the aqueous phase follow very well the general understanding of the relative sorption strength of the tracers, as inferred from e.g. batch sorption experiments and dynamic in situ tracer experiments. The chemical speciation calculations of the different tracers were in line with the results of the ion exchange speciation performed during the experiment. With the exception of UO 2 2+ carbonate complexes formed, no strong indications were obtained that aqueous complexation prevents adsorption under the chemical conditions of the experiment. The 20 nm filtered sampling indicated that radionuclide

  17. Long Term Sorption Diffusion Experiment (LTDE-SD). Performance of main in situ experiment and results from water phase measurements

    Energy Technology Data Exchange (ETDEWEB)

    Widestrand, Henrik; Byegaard, Johan; Nilsson, Kersti; Hoeglund, Susanne; Gustafsson, Erik (Geosigma AB, Uppsala (Sweden)); Kronberg, Magnus (Swedish Nuclear Fuel and Waste Management Co. (Sweden))

    2010-12-15

    The LTDE-SD experiment, (Long Term Sorption Diffusion Experiment) aimed at increasing the scientific knowledge of sorption and diffusion under in situ conditions and to provide data for performance and safety assessment calculations. Performance and results of the in situ experiment phase are presented in the report. In total, 21 radionuclide trace elements and one stable trace element were injected, circulated and sampled for approx6.5 months in a closed borehole section. The trace elements represented non-sorbing tracers and sorbing tracers for which the sorption was dominated by a cation exchange mechanism, a surface complexation mechanism, or dependent on an electrochemical reduction in order to reach the tetravalent state (oxidation state IV) considered very strongly sorbing. The borehole section in contact with the tracer labelled groundwater consisted in part of a natural fracture surface and a borehole section in the unaltered matrix rock, devoid of natural fractures. Water samples were regularly extracted and analysed for trace element concentration and a few ion exchange speciation and filtered samplings were also conducted. Independent colloid filtering and chemical speciation calculations were performed in support the evaluation. Sorption was demonstrated for a series of elements present in the experiment. The amounts lost of the different respective tracers from the aqueous phase follow very well the general understanding of the relative sorption strength of the tracers, as inferred from e.g. batch sorption experiments and dynamic in situ tracer experiments. The chemical speciation calculations of the different tracers were in line with the results of the ion exchange speciation performed during the experiment. With the exception of UO{sub 2} 2+ carbonate complexes formed, no strong indications were obtained that aqueous complexation prevents adsorption under the chemical conditions of the experiment. The 20 nm filtered sampling indicated that

  18. Sensitivity of the photodissociation of NO2, NO3, HNO3 and H2O2 to the solar radiation diffused by the ground and by atmospheric particles

    International Nuclear Information System (INIS)

    Mugnai, A.; Petroncelli, P.; Fiocco, G.

    1979-01-01

    The diffusion of solar radiation by atmospheric molecules and aerosols and by ground albedo affects the photodissociation rates of atmospheric species relevant to the ozone chemistry. In this paper, a previous investigation on the photodissociation of O 3 is extended to NO 2 , NO 3 , HNO 3 , H 2 O 2 . Because of the different character of the absorption spectra of these species, the behaviour of photodissociation profiles with height and their sensitivity to such factors as ground albedo, aerosol loads, solar zenith angle are somewhat different. The results show that the presence of the aerosols usually enhances the photodissociation in the upper troposphere and in the stratosphere, because of scattering, but tends to reduce it at low heights because of the increased extinction. Enhancements in the photodissociation coefficients are as high as 20 to 40% for low values of the albedo and large aerosol loads such as those obtained after a volcanic eruption. On the other hand, at large values of the albedo, the effect of aerosols is mainly in attenuating the radiation going into and coming from the ground and their presence can lead to reduced photolysis even in the stratosphere. (author)

  19. The back-diffusion effect of air on the discharge characteristics of atmospheric-pressure radio-frequency glow discharges using bare metal electrodes

    International Nuclear Information System (INIS)

    Sun Wenting; Liang Tianran; Wang Huabo; Li Heping; Bao Chengyu

    2007-01-01

    Radio-frequency (RF), atmospheric-pressure glow discharge (APGD) plasmas using bare metal electrodes have promising prospects in the fields of plasma-aided etching, deposition, surface treatment, disinfection, sterilization, etc. In this paper, the discharge characteristics, including the breakdown voltage and the discharge voltage for sustaining a stable and uniform α mode discharge of the RF APGD plasmas are presented. The experiments are conducted by placing the home-made planar-type plasma generator in ambient and in a vacuum chamber, respectively, with helium as the primary plasma-forming gas. When the discharge processes occur in ambient, particularly for the lower plasma-working gas flow rates, the experimental measurements show that it is the back-diffusion effect of air in atmosphere, instead of the flow rate of the gas, that results in the obvious decrease in the breakdown voltage with increasing plasma-working gas flow rate. Further studies on the discharge characteristics, e.g. the luminous structures, the concentrations and distributions of chemically active species in plasmas, with different plasma-working gases or gas mixtures need to be conducted in future work

  20. On the origin and meaning of the German word Luft and some meteorological terms concerning atmospheric water, especially fog

    Directory of Open Access Journals (Sweden)

    Möller, Detlev

    2014-12-01

    Full Text Available The English and French word “air” is derived from the Latin aer, which comes from the Greek άήρ. In contrast, the German word “Luft” is a common Proto-Germanic word; in Old English “ lift” and “ lyft”. The word Luft (also Danish, Swedish and Norwegian is associated with brightness; the German Licht (light, an air (in an atmospheric sense without fog or clouds. Air and water were originally “elements” in ancient Greek and were transmutable; they represented two kinds of the “ layer of mist” (atmosphere. Dark or thick air was mist or cloud, hiding the gods (who lived in the upper air or sky; the aether. Different terms are presented that describe fog and clouds in connection with the history of the process of understanding. Finally, the word Luft (air as a term for gaseous chemical compounds (“kinds of gases” is discussed. In addition to the German, all terms are given in Greek, Latin, English and French .

  1. Technical Note: Long-term memory effect in the atmospheric CO2 concentration at Mauna Loa

    Directory of Open Access Journals (Sweden)

    C. Varotsos

    2007-01-01

    Full Text Available The monthly mean values of the atmospheric carbon dioxide concentration derived from in-situ air samples collected at Mauna Loa Observatory, Hawaii, USA during 1958–2004 (the longest continuous record available in the world are analyzed by employing the detrended fluctuation analysis to detect scaling behavior in this time series. The main result is that the fluctuations of carbon dioxide concentrations exhibit long-range power-law correlations (long memory with lag times ranging from four months to eleven years, which correspond to 1/f noise. This result indicates that random perturbations in the carbon dioxide concentrations give rise to noise, characterized by a frequency spectrum following a power-law with exponent that approaches to one; the latter shows that the correlation times grow strongly. This feature is pointing out that a correctly rescaled subset of the original time series of the carbon dioxide concentrations resembles the original time series. Finally, the power-law relationship derived from the real measurements of the carbon dioxide concentrations could also serve as a tool to improve the confidence of the atmospheric chemistry-transport and global climate models.

  2. Measuring the diffusion of palliative care in long-term care facilities – a death census

    Directory of Open Access Journals (Sweden)

    Santos-Eggimann Brigitte

    2009-01-01

    Full Text Available Abstract Background The dissemination of palliative care for patients presenting complex chronic diseases at various stages has become an important matter of public health. A death census in Swiss long-term care facilities (LTC was set up with the aim of monitoring the frequency of selected indicators of palliative care. Methods The survey covered 150 LTC facilities (105 nursing homes and 45 home health services, each of which was asked to complete a questionnaire for every non-accidental death over a period of six months. The frequency of 4 selected indicators of palliative care (resort to a specialized palliative care service, the administration of opiates, use of any pain measurement scale or other symptom measurement scale was monitored in respect of the stages of care and analysed based on gender, age, medical condition and place of residence. Results Overall, 1200 deaths were reported, 29.1% of which were related to cancer. The frequencies of each indicator varied according to the type of LTC, mostly regarding the administration of opiate. It appeared that the access to palliative care remained associated with cancer, terminal care and partly with age, whereas gender and the presence of mental disorders had no effect on the indicators. In addition, the use of drugs was much more frequent than the other indicators. Conclusion The profile of patients with access to palliative care must become more diversified. Among other recommendations, equal access to opiates in nursing homes and in home health services, palliative care at an earlier stage and the systematic use of symptom management scales when resorting to opiates have to become of prime concern.

  3. Normal white matter microstructure in women long-term recovered from anorexia nervosa: A diffusion tensor imaging study.

    Science.gov (United States)

    Bang, Lasse; Rø, Øyvind; Endestad, Tor

    2018-01-01

    Studies point to white matter (WM) microstructure alterations in both adolescent and adult patients with anorexia nervosa (AN). These include reduced fractional anisotropy in several WM fiber tracts, suggesting reduced WM integrity. The extent to which these alterations are reversible with recovery from AN is unclear. There is a paucity of research investigating the presence of WM microstructure alterations in recovered AN patients, and results are inconsistent. This study aimed to investigate the presence of WM microstructure alterations in women long-term recovered from AN. Twenty-one adult women who were recovered from AN for at least 1 year were compared to 21 adult comparison women. Participants were recruited via user-organizations for eating disorders, local advertisements, and online forums. Diffusion tensor imaging was used to compare WM microstructure between groups. Correlations between WM microstructure and clinical characteristics were also explored. There were no statistically significant between-group differences in WM microstructure. These null findings remained when employing liberal alpha level thresholds. Furthermore, there were no statistically significant correlations between WM microstructure and clinical characteristics. Our findings showed normal WM microstructure in long-term recovered patients, indicating the alterations observed during the acute phase are reversible. Given the paucity of research and inconsistent findings, future studies are warranted to determine the presence of WM microstructure alterations following recovery from AN. © 2017 Wiley Periodicals, Inc.

  4. LOSCAR: Long-term Ocean-atmosphere-Sediment CArbon cycle Reservoir Model v2.0.4

    Directory of Open Access Journals (Sweden)

    R. E. Zeebe

    2012-01-01

    Full Text Available The LOSCAR model is designed to efficiently compute the partitioning of carbon between ocean, atmosphere, and sediments on time scales ranging from centuries to millions of years. While a variety of computationally inexpensive carbon cycle models are already available, many are missing a critical sediment component, which is indispensable for long-term integrations. One of LOSCAR's strengths is the coupling of ocean-atmosphere routines to a computationally efficient sediment module. This allows, for instance, adequate computation of CaCO3 dissolution, calcite compensation, and long-term carbon cycle fluxes, including weathering of carbonate and silicate rocks. The ocean component includes various biogeochemical tracers such as total carbon, alkalinity, phosphate, oxygen, and stable carbon isotopes. LOSCAR's configuration of ocean geometry is flexible and allows for easy switching between modern and paleo-versions. We have previously published applications of the model tackling future projections of ocean chemistry and weathering, pCO2 sensitivity to carbon cycle perturbations throughout the Cenozoic, and carbon/calcium cycling during the Paleocene-Eocene Thermal Maximum. The focus of the present contribution is the detailed description of the model including numerical architecture, processes and parameterizations, tuning, and examples of input and output. Typical CPU integration times of LOSCAR are of order seconds for several thousand model years on current standard desktop machines. The LOSCAR source code in C can be obtained from the author by sending a request to loscar.model@gmail.com.

  5. Inverse modeling of the Chernobyl source term using atmospheric concentration and deposition measurements

    Science.gov (United States)

    Evangeliou, Nikolaos; Hamburger, Thomas; Cozic, Anne; Balkanski, Yves; Stohl, Andreas

    2017-07-01

    This paper describes the results of an inverse modeling study for the determination of the source term of the radionuclides 134Cs, 137Cs and 131I released after the Chernobyl accident. The accident occurred on 26 April 1986 in the Former Soviet Union and released about 1019 Bq of radioactive materials that were transported as far away as the USA and Japan. Thereafter, several attempts to assess the magnitude of the emissions were made that were based on the knowledge of the core inventory and the levels of the spent fuel. More recently, when modeling tools were further developed, inverse modeling techniques were applied to the Chernobyl case for source term quantification. However, because radioactivity is a sensitive topic for the public and attracts a lot of attention, high-quality measurements, which are essential for inverse modeling, were not made available except for a few sparse activity concentration measurements far from the source and far from the main direction of the radioactive fallout. For the first time, we apply Bayesian inversion of the Chernobyl source term using not only activity concentrations but also deposition measurements from the most recent public data set. These observations refer to a data rescue attempt that started more than 10 years ago, with a final goal to provide available measurements to anyone interested. In regards to our inverse modeling results, emissions of 134Cs were estimated to be 80 PBq or 30-50 % higher than what was previously published. From the released amount of 134Cs, about 70 PBq were deposited all over Europe. Similar to 134Cs, emissions of 137Cs were estimated as 86 PBq, on the same order as previously reported results. Finally, 131I emissions of 1365 PBq were found, which are about 10 % less than the prior total releases. The inversion pushes the injection heights of the three radionuclides to higher altitudes (up to about 3 km) than previously assumed (≈ 2.2 km) in order to better match both concentration

  6. Inverse modeling of the Chernobyl source term using atmospheric concentration and deposition measurements

    Directory of Open Access Journals (Sweden)

    N. Evangeliou

    2017-07-01

    Full Text Available This paper describes the results of an inverse modeling study for the determination of the source term of the radionuclides 134Cs, 137Cs and 131I released after the Chernobyl accident. The accident occurred on 26 April 1986 in the Former Soviet Union and released about 1019 Bq of radioactive materials that were transported as far away as the USA and Japan. Thereafter, several attempts to assess the magnitude of the emissions were made that were based on the knowledge of the core inventory and the levels of the spent fuel. More recently, when modeling tools were further developed, inverse modeling techniques were applied to the Chernobyl case for source term quantification. However, because radioactivity is a sensitive topic for the public and attracts a lot of attention, high-quality measurements, which are essential for inverse modeling, were not made available except for a few sparse activity concentration measurements far from the source and far from the main direction of the radioactive fallout. For the first time, we apply Bayesian inversion of the Chernobyl source term using not only activity concentrations but also deposition measurements from the most recent public data set. These observations refer to a data rescue attempt that started more than 10 years ago, with a final goal to provide available measurements to anyone interested. In regards to our inverse modeling results, emissions of 134Cs were estimated to be 80 PBq or 30–50 % higher than what was previously published. From the released amount of 134Cs, about 70 PBq were deposited all over Europe. Similar to 134Cs, emissions of 137Cs were estimated as 86 PBq, on the same order as previously reported results. Finally, 131I emissions of 1365 PBq were found, which are about 10 % less than the prior total releases. The inversion pushes the injection heights of the three radionuclides to higher altitudes (up to about 3 km than previously assumed (≈ 2.2 km in order

  7. Aerodynamic modeling of the lower part of the atmospheric boundary layer

    International Nuclear Information System (INIS)

    Mohamed, K.S.

    1992-01-01

    In this thesis , we present a study dealing with the basic meteorology concepts commonly used in air pollution. The pollutant motion in the atmosphere together with its basic mathematical concepts have been reviewed. This review includes; atmospheric forces acting on a particle, atmospheric turbulence, atmospheric stability and the most widely used atmospheric diffusion models. The resistance for pollutant transfer for different atmospheric stability classes has been derived in terms of both wind velocity profile parameters and diffusion coefficients. Therefrom, the residence time of a pollutant in the atmosphere is obtained. The dust particle trajectory and deposition in case of neutral atmosphere is formulated mathematically adopting particle Gaussian distribution. An analytical treatment for the diffusion equation with extension of the boundary conditions to include the ground surface absorption of pollutants and presence of elevated inversion layer, has been presented . The concept of decay distance is introduced and applied in a sample calculation for the dispersion of pollutants over growing wheat field

  8. Tritium uptake in cultivated plants after short-term exposure to atmospheric tritium

    International Nuclear Information System (INIS)

    Diabate, S.; Strack, S.; Paunescu, N.

    1998-01-01

    The tritium behavior in crop plants is of particular interest for the prediction of doses to humans due to ingestion. Tritium is present in plants in two forms: tritium free water tissue (TWT) and organically bound tritium (OBT). The both forms are to be considered in models calculating the ingestion dose. Potato plants belong to the major food crops in many countries and were chosen as representatives of crops whose edible parts grow under ground. Green bean were chosen as representatives of vegetables relevant in human diet. This vegetable may be consumed as green pod and it may be conserved over a long period of time. Green bean and potato plants were exposed to tritiated water vapor in the atmosphere during their generative phase of development. The uptake of tritium and the conversion into organic matter was studied under laboratory conditions at two different light intensities. The tritium concentrations in plants were followed until harvest. In leaves, the tritium uptake into tissue water under night conditions was 5-6 times lower than under day-time conditions. The initial incorporation into organic matter under night conditions was 0.7% of the tissue water concentration in leaves of both plant species. However, under light irradiation, this value increased to only 1.8% in bean leaves and 0.9% in potato leaves, which indicates a participation of processes other than photosynthesis in tritium incorporation into organic material. Organically bound tritium (OBT) was translocated into pods and tubers which represented a high percentage of the total organically bound tritium at harvest. The behavior of total OBT in all plants under study showed that OBT, once generated, is lost very slowly until harvest, in particular when storage organs of plants were in their phase of development at the time of exposure. OBT is translocated into the storage organs which may be used in the human diet and thus may contribute to the ingestion dose for a long time after the

  9. Long-term Impacts of Hurricane Wilma on Land Surface-Atmosphere Exchanges

    Science.gov (United States)

    Fuentes, J. D.; Dowell, K. K.; Engel, V. C.; Smith, T. J.

    2008-05-01

    In October 2005, Hurricane Wilma made landfall along the mangrove forests of western Everglades National Park, Florida, USA. Damage from the storm varied with distance from landfall and included widespread mortality and extensive defoliation. Large sediment deposition events were recorded in the interior marshes, with erosion taking place along the coastal margins. Wilma made landfall near a 30 m flux tower where eddy-covariance measurements of ecosystem-level carbon and energy fluxes started in 2003. Repairs to the structure were completed in 2006, enabling comparisons of surface fluxes before and after the storm. One year after the hurricane, both the average and daily integrated CO2 fluxes are consistently lower than the pre-storm values. The storm's impact on standing live biomass and the slow recovery of leaf area appear to have resulted in decreased photosynthetic uptake capacity. Nighttime respiratory CO2 fluxes above the canopy are unchanged from pre-storm values. During some periods, daily integrated fluxes show the forest as a net source of CO2 to the atmosphere. Soil CO2 fluxes are not measured directly, but daytime soil temperatures and vertical heat fluxes have shown consistently higher values after the storm. Nighttime soil temperatures values have been slightly lower. These stronger diurnal soil temperature fluctuations indicate enhanced radiative fluxes at the soil surface, possibly as a result of the reduced leaf area. The increases in daytime soil temperatures are presumably leading to higher below-ground respiration rates and, along with the reduced photosynthetic capacity, contributing to the lower net CO2 assimilation rates. This hypothesis is supported by nearby measurements of declining surface elevations of the organic soils which have been correlated with mangrove mortality in impacted areas. Both sensible and latent heat fluxes above the canopy are found to be reduced following the hurricane, and soil heat storage is higher. Together

  10. Long Term Variations of the Atmospheric Air Pollutants in Istanbul City

    Directory of Open Access Journals (Sweden)

    H. Kurtulus Ozcan

    2012-03-01

    Full Text Available High population density and intense industrial activity has resulted in various forms of pollution in megacities. Air pollution ranks at the top of this list. This study investigated long-term changes in air pollutant parameters (SO2, CO, NO, NO2, NOx in Istanbul City, Turkey, using data from air-quality measurement stations on the Asian and European sides of Istanbul. The results show decreases from 2002 to 2010 in the amounts of SO2 (one of the main pollutants released as a result of the burning of fossil fuels and CO (indicative of incomplete combustion. However, NOx concentrations showed fluctuations over time, rather than a steady decline throughout the study period.

  11. Modelling impacts of atmospheric deposition and temperature on long-term DOC trends.

    Science.gov (United States)

    Sawicka, K; Rowe, E C; Evans, C D; Monteith, D T; E I Vanguelova; Wade, A J; J M Clark

    2017-02-01

    It is increasingly recognised that widespread and substantial increases in Dissolved organic carbon (DOC) concentrations in remote surface, and soil, waters in recent decades are linked to declining acid deposition. Effects of rising pH and declining ionic strength on DOC solubility have been proposed as potential dominant mechanisms. However, since DOC in these systems is derived mainly from recently-fixed carbon, and since organic matter decomposition rates are considered sensitive to temperature, uncertainty persists over the extent to which other drivers that could influence DOC production. Such potential drivers include fertilisation by nitrogen (N) and global warming. We therefore ran the dynamic soil chemistry model MADOC for a range of UK soils, for which time series data are available, to consider the likely relative importance of decreased deposition of sulphate and chloride, accumulation of reactive N, and higher temperatures, on soil DOC production in different soils. Modelled patterns of DOC change generally agreed favourably with measurements collated over 10-20years, but differed markedly between sites. While the acidifying effect of sulphur deposition appeared to be the predominant control on the observed soil water DOC trends in all the soils considered other than a blanket peat, the model suggested that over the long term, the effects of nitrogen deposition on N-limited soils may have been sufficient to raise the "acid recovery DOC baseline" significantly. In contrast, reductions in non-marine chloride deposition and effects of long term warming appeared to have been relatively unimportant. The suggestion that future DOC concentrations might exceed preindustrial levels as a consequence of nitrogen pollution has important implications for drinking water catchment management and the setting and pursuit of appropriate restoration targets, but findings still require validation from reliable centennial-scale proxy records, such as those being developed

  12. On the formation mechanisms of the diffuse atmospheric pressure dielectric barrier discharge in CVD processes of thin silica-like films

    Energy Technology Data Exchange (ETDEWEB)

    Starostin, S A; Premkumar, P Antony [Materials Innovation Institute (M2i), Mekelweg 2, 2600 GA Delft, The Netherland (Netherlands); Creatore, M; Van Veldhuizen, E M; Van de Sanden, M C M [Department of Applied Physics, Eindhoven University of Technology, 5600 MB Eindhoven (Netherlands); De Vries, H; Paffen, R M J [FUJIFILM Manufacturing Europe B.V, PO Box 90156, Tilburg (Netherlands)

    2009-11-15

    Pathways of formation and temporal evolution of the diffuse dielectric barrier discharge at atmospheric pressure were experimentally studied in this work by means of optical (fast imaging camera) and electrical diagnostics. The chosen model system is relevant for applications of plasma-enhanced chemical vapor deposition of thin silica-like film on the polymeric substrate, from cost-efficient gas mixtures of Ar/N{sub 2}/O{sub 2}/hexamethyldisiloxane. It was found that the discharge can gradually experience the phases of homogeneous low current Townsend-like mode, local Townsend to glow transition and expanding high current density ({approx}0.7 A cm{sup -2}) glow-like mode. While the glow-like current spot occupies momentarily only a small part of the electrode area, its expanding behavior provides uniform treatment of the whole substrate surface. Alternatively, it was observed that a visually uniform discharge can be formed by the numerous microdischarges overlapping over the large electrode area.

  13. Long-segment plication technique for arteriovenous fistulae threatened by diffuse aneurysmal degeneration: short-term results.

    Science.gov (United States)

    Powell, Alexis; Wooster, Mathew; Carroll, Megan; Cardentey-Oliva, Damian; Cavanagh-Voss, Sean; Armstrong, Paul; Shames, Murray; Illig, Karl; Gabbard, Wesley

    2015-08-01

    A substantial number of patients with autologous arteriovenous fistulas (AVFs) develop diffuse aneurysmal degeneration, which frequently interferes with successful access. These AVFs are often deemed unsalvageable. We hypothesize that long-segment plication in these patients can be performed safely with acceptable short-term AVF salvage rates. We reviewed a prospectively maintained database to identify all patients with extensive AVF aneurysmal disease operated on for this problem. Thirty-five patients, 25 (71%) male and 10 (29%) female were operated on between July 2012 and January 2014. AVFs included 23 (66%) brachiocephalic, 5 (14%) radiocephalic, and 7 brachiobasilic (20%) fistulae (one first stage only but in use). The cohort had one or a combination of local pain, arm edema, cannulation issue, recurrent thrombosis, dysfunctional during dialysis, or extreme tortuousity. Time range for AVF creation to consultation ranged from 3 months to 11 years. All underwent long-segment plication over a 20-Fr Bougie with or without segmental vein resection; 3 underwent concomitant first rib resection for costoclavicular stenosis; 21 patients had tunneled catheter placement for use while healing, whereas 13 were allowed segmental use of their AVF during the perioperative period (1 patient was not yet on dialysis). Early in our experience, AVFs were left under the wound, whereas all but one repaired since early 2013 were left under a lateral flap. All patients were followed by clinical examination and duplex. In the 30-day postoperative period, 2 AVFs (5.7%) became infected requiring excision, 2 occluded (5.7%), 1 day 1 and the other at 24 days out, 1 patient developed steal and required DRIL 1 week postoperatively, and 1 patient died, unrelated to his surgery. Postoperative functional primary patency was 88% (30 of 34). Of the patients needing temporary access catheter, mean time to first fistula use was 44 days. No wound or bleeding complications have occurred in repaired

  14. Seasonal phosphatase activity in three characteristic soils of the English uplands polluted by long-term atmospheric nitrogen deposition

    International Nuclear Information System (INIS)

    Turner, B.L.; Baxter, Robert; Whitton, B.A.

    2002-01-01

    High soil phosphatase activities confirm strong biological phosphorus limitations due to nitrogen deposition. - Phosphomonoesterase activities were determined monthly during a seasonal cycle in three characteristic soil types of the English uplands that have been subject to long-term atmospheric nitrogen deposition. Activities (μmol para-nitrophenol g -1 soil dry wt. h -1 ) ranged between 83.9 and 307 in a blanket peat (total carbon 318 mg g -1 , pH 3.9), 45.2-86.4 in an acid organic grassland soil (total carbon 354 mg g -1 , pH 3.7) and 10.4-21.1 in a calcareous grassland soil (total carbon 140 mg g -1 , pH 7.3). These are amongst the highest reported soil phosphomonoesterase activities and confirm the strong biological phosphorus limitation in this environment

  15. Diffusion in building wakes

    International Nuclear Information System (INIS)

    Ramsdell, J.V.

    1988-03-01

    Straight-line Gaussian models adequately describe atmospheric diffusion for many applications. They have been modified for use in estimating diffusion in building wakes by adding terms that include projected building area and by redefining the diffusion coefficients so that the coefficients have minimum values that are related to building dimensions. In a recent study, Ramsdell reviewed the building-wake dispersion models used by the Nuclear Regulatory Commission (NRC) in its control room habitability assessments. The review included comparison of model estimates of centerline concentrations with concentrations observed in experiments at seven nuclear reactors. In general, the models are conservative in that they tend to predict concentrations that are greater than those actually observed. However, the models show little skill in accounting for variations in the observed concentrations. Subsequently, the experimental data and multiples linear regression techniques have been used to develop a new building wake diffusion model. This paper describes the new building wake model and compares it with other models. 8 refs., 2 figs

  16. The long term recovery of heat and moisture fluxes to the atmosphere following fire in Australia's tropical savanna

    Science.gov (United States)

    Tapper, N.; Beringer, J.; Hutley, L.; Coutts, A.

    2003-04-01

    Fire is probably the greatest natural and anthropogenic environmental disturbance in Australia's tropical savannas, with the vast area burned each year (up to 250,000 km^2) likely to increase with predicted regional climate change. Globally savanna ecosystems cover 11.5% of the global landscape (Scholes and Hall 1996). As much as 75% of this landscape burns annually (Hao et al., 1990), accounting for more than 40% of all global biomass consumed (Hao and Ward 1993). These landscape-scale fires undoubtedly have massive impacts on regional water, energy and carbon dioxide exchanges and as a result may have important feedbacks to the atmosphere and regional climate. Fire may influence climate directly through the emission of smoke and trace gases from burning, but there are other important impacts of fire that may affect the atmosphere. Fire and the subsequent fire scars are likely to radically alter the surface energy budgets of tropical savannas through reduced surface albedo, increased available energy for partitioning into the convective fluxes, and increased substrate heat flux. The aerodynamic and biological properties of the ecosystem may also change, affecting surface-atmosphere coupling. There is a clear potential to influence atmospheric motion and moist convection at a range of scales. Potential fire scar impacts such as those mentioned above have previously been largely ignored and are the focus of the Savanna Fire Experiment (SAFE). Tower measurements of radiation, heat, moisture and CO_2 fluxes above burned and unburned savanna near Darwin, Australia, were initiated in August 2001 to observe the impacts of fire and fire scarring on flux exchange with the atmosphere, along with the longer term post-fire recovery of fluxes. Intensive field campaigns were mounted in the dry (fire) seasons of both 2001 and 2002, with flux recovery observed into the each of the subsequent monsoon seasons. Results and an early analysis of the time series of heat and moisture

  17. Long-term effects of radiation therapy on white matter of the corpus callosum: a diffusion tensor imaging study in children

    Energy Technology Data Exchange (ETDEWEB)

    Makola, Monwabisi [University of Cincinnati, College of Medicine, Cincinnati, OH (United States); Douglas Ris, M. [Texas Children' s Hospital, Department of Pediatrics, Baylor College of Medicine, Houston, TX (United States); Mahone, E.M. [Kennedy Krieger Institute, Department of Neuropsychology, Baltimore, MD (United States); Johns Hopkins University School of Medicine, Department of Psychiatry and Behavioral Sciences, Baltimore, MD (United States); Yeates, Keith Owen [University of Calgary, Department of Psychology, Alberta Children' s Hospital Research Institute, Hotchkiss Brain Institute, Calgary, AB (Canada); Cecil, Kim M. [Imaging Research Center, Cincinnati Children' s Hospital Medical Center, Cincinnati, OH (United States); University of Cincinnati College of Medicine, Department of Radiology, Cincinnati, OH (United States); University of Cincinnati College of Medicine, Department of Pediatrics, Cincinnati, OH (United States); University of Cincinnati College of Medicine, Neuroscience Graduate Program, Cincinnati, OH (United States); University of Cincinnati College of Medicine, Department of Environmental Health, Cincinnati, OH (United States)

    2017-12-15

    Despite improving survival rates, children are at risk for long-term cognitive and behavioral difficulties following the diagnosis and treatment of a brain tumor. Surgery, chemotherapy and radiation therapy have all been shown to impact the developing brain, especially the white matter. The purpose of this study was to determine the long-term effects of radiation therapy on white matter integrity, as measured by diffusion tensor imaging, in pediatric brain tumor patients 2 years after the end of radiation treatment, while controlling for surgical interventions. We evaluated diffusion tensor imaging performed at two time points: a baseline 3 to 12 months after surgery and a follow-up approximately 2 years later in pediatric brain tumor patients. A region of interest analysis was performed within three regions of the corpus callosum. Diffusion tensor metrics were determined for participants (n=22) who underwent surgical tumor resection and radiation therapy and demographically matched with participants (n=22) who received surgical tumor resection only. Analysis revealed that 2 years after treatment, the radiation treated group exhibited significantly lower fractional anisotropy and significantly higher radial diffusivity within the body of the corpus callosum compared to the group that did not receive radiation. The findings indicate that pediatric brain tumor patients treated with radiation therapy may be at greater risk of experiencing long-term damage to the body of the corpus callosum than those treated with surgery alone. (orig.)

  18. Long-term effects of radiation therapy on white matter of the corpus callosum: a diffusion tensor imaging study in children

    International Nuclear Information System (INIS)

    Makola, Monwabisi; Douglas Ris, M.; Mahone, E.M.; Yeates, Keith Owen; Cecil, Kim M.

    2017-01-01

    Despite improving survival rates, children are at risk for long-term cognitive and behavioral difficulties following the diagnosis and treatment of a brain tumor. Surgery, chemotherapy and radiation therapy have all been shown to impact the developing brain, especially the white matter. The purpose of this study was to determine the long-term effects of radiation therapy on white matter integrity, as measured by diffusion tensor imaging, in pediatric brain tumor patients 2 years after the end of radiation treatment, while controlling for surgical interventions. We evaluated diffusion tensor imaging performed at two time points: a baseline 3 to 12 months after surgery and a follow-up approximately 2 years later in pediatric brain tumor patients. A region of interest analysis was performed within three regions of the corpus callosum. Diffusion tensor metrics were determined for participants (n=22) who underwent surgical tumor resection and radiation therapy and demographically matched with participants (n=22) who received surgical tumor resection only. Analysis revealed that 2 years after treatment, the radiation treated group exhibited significantly lower fractional anisotropy and significantly higher radial diffusivity within the body of the corpus callosum compared to the group that did not receive radiation. The findings indicate that pediatric brain tumor patients treated with radiation therapy may be at greater risk of experiencing long-term damage to the body of the corpus callosum than those treated with surgery alone. (orig.)

  19. Language development at 2 years is correlated to brain microstructure in the left superior temporal gyrus at term equivalent age: a diffusion tensor imaging study.

    Science.gov (United States)

    Aeby, Alec; De Tiège, Xavier; Creuzil, Marylise; David, Philippe; Balériaux, Danielle; Van Overmeire, Bart; Metens, Thierry; Van Bogaert, Patrick

    2013-09-01

    This study aims at testing the hypothesis that neurodevelopmental abilities at age 2 years are related with local brain microstructure of preterm infants at term equivalent age. Forty-one preterm infants underwent brain MRI with diffusion tensor imaging sequences to measure mean diffusivity (MD), fractional anisotropy (FA), longitudinal and transverse diffusivity (λ// and λ[perpendicular]) at term equivalent age. Neurodevelopment was assessed at 2 years corrected age using the Bayley III scale. A voxel-based analysis approach, statistical parametric mapping (SPM8), was used to correlate changes of the Bayley III scores with the regional distribution of MD, FA, λ// and λ[perpendicular]. We found that language abilities are negatively correlated to MD, λ// and λ[perpendicular] in the left superior temporal gyrus in preterm infants. These findings suggest that higher MD, λ// and λ[perpendicular] values at term-equivalent age in the left superior temporal gyrus are associated with poorer language scores in later childhood. Consequently, it highlights the key role of the left superior temporal gyrus for the development of language abilities in children. Further studies are needed to assess on an individual basis and on the long term the prognostic value of brain DTI at term equivalent age for the development of language. Copyright © 2013 Elsevier Inc. All rights reserved.

  20. Dynamic imaging response following radiation therapy predicts long-term outcomes for diffuse low-grade gliomas.

    Science.gov (United States)

    Pallud, Johan; Llitjos, Jean-François; Dhermain, Frédéric; Varlet, Pascale; Dezamis, Edouard; Devaux, Bertrand; Souillard-Scémama, Raphaëlle; Sanai, Nader; Koziak, Maria; Page, Philippe; Schlienger, Michel; Daumas-Duport, Catherine; Meder, Jean-François; Oppenheim, Catherine; Roux, François-Xavier

    2012-04-01

    Quantitative imaging assessment of radiation therapy (RT) for diffuse low-grade gliomas (DLGG) by measuring the velocity of diametric expansion (VDE) over time has never been studied. We assessed the VDE changes following RT and determined whether this parameter can serve as a prognostic factor. We reviewed a consecutive series of 33 adults with supratentorial DLGG treated with first-line RT with available imaging follow-up (median follow-up, 103 months). Before RT, all patients presented with a spontaneous tumor volume increase (positive VDE, mean 5.9 mm/year). After RT, all patients demonstrated a tumor volume decrease (negative VDE, mean, -16.7 mm/year) during a mean 49-month duration. In univariate analysis, initial tumor volume (>100 cm(3)), lack of IDH1 expression, p53 expression, high proliferation index, and fast post-RT tumor volume decrease (VDE at -10 mm/year or faster, fast responders) were associated with a significantly shorter overall survival (OS). The median OS was significantly longer (120.8 months) for slow responders (post-RT VDE slower than -10.0 mm/year) than for fast responders (47.9 months). In multivariate analysis, fast responders, larger initial tumor volume, lack of IDH1 expression, and p53 expression were independent poor prognostic factors for OS. A high proliferation index was significantly more frequent in the fast responder subgroup than in the slow responder subgroup. We conclude that the pattern of post-RT VDE changes is an independent prognostic factor for DLGG and offers a quantitative parameter to predict long-term outcomes. We propose to monitor individually the post-RT VDE changes using MRI follow-up, with particular attention to fast responders.

  1. Increasing Juniperus virginiana L. pollen in the Tulsa atmosphere: long-term trends, variability, and influence of meteorological conditions

    Science.gov (United States)

    Flonard, Michaela; Lo, Esther; Levetin, Estelle

    2018-02-01

    In the Tulsa area, the Cupressaceae is largely represented by eastern red cedar ( Juniperus virginiana L.). The encroachment of this species into the grasslands of Oklahoma has been well documented, and it is believed this trend will continue. The pollen is known to be allergenic and is a major component of the Tulsa atmosphere in February and March. This study examined airborne Cupressaceae pollen data from 1987 to 2016 to determine long-term trends, pollen seasonal variability, and influence of meteorological variables on airborne pollen concentrations. Pollen was collected through means of a Burkard sampler and analyzed with microscopy. Daily pollen concentrations and yearly pollen metrics showed a high degree of variability. In addition, there were significant increases over time in the seasonal pollen index and in peak concentrations. These increases parallel the increasing population of J. virginiana in the region. Pollen data were split into pre- and post-peak categories for statistical analyses, which revealed significant differences in correlations of the two datasets when analyzed with meteorological conditions. While temperature and dew point, among others were significant in both datasets, other factors, like relative humidity, were significant only in one dataset. Analyses using wind direction showed that southerly and southwestern winds contributed to increased pollen concentrations. This study confirms that J. virginiana pollen has become an increasing risk for individuals sensitive to this pollen and emphasizes the need for long-term aerobiological monitoring in other areas.

  2. Long-term performance of activated carbon air cathodes with different diffusion layer porosities in microbial fuel cells

    KAUST Repository

    Zhang, Fang; Pant, Deepak; Logan, Bruce E.

    2011-01-01

    to examine the reasons for the degraded performance. Diffusion resistance in the cathode was found to be the primary component of the internal resistance, and it increased over time. Replacing the cathode after 1 year completely restored the original power

  3. Drivers for spatial, temporal and long-term trends in atmospheric ammonia and ammonium in the UK

    Directory of Open Access Journals (Sweden)

    Y. S. Tang

    2018-01-01

    Full Text Available A unique long-term dataset from the UK National Ammonia Monitoring Network (NAMN is used here to assess spatial, seasonal and long-term variability in atmospheric ammonia (NH3: 1998–2014 and particulate ammonium (NH4+: 1999–2014 across the UK. Extensive spatial heterogeneity in NH3 concentrations is observed, with lowest annual mean concentrations at remote sites (< 0.2 µg m−3 and highest in the areas with intensive agriculture (up to 22 µg m−3, while NH4+ concentrations show less spatial variability (e.g. range of 0.14 to 1.8 µg m−3 annual mean in 2005. Temporally, NH3 concentrations are influenced by environmental conditions and local emission sources. In particular, peak NH3 concentrations are observed in summer at background sites (defined by 5 km grid average NH3 emissions < 1 kg N ha−1 yr−1 and in areas dominated by sheep farming, driven by increased volatilization of NH3 in warmer summer temperatures. In areas where cattle, pig and poultry farming is dominant, the largest NH3 concentrations are in spring and autumn, matching periods of manure application to fields. By contrast, peak concentrations of NH4+ aerosol occur in spring, associated with long-range transboundary sources. An estimated decrease in NH3 emissions by 16 % between 1998 and 2014 was reported by the UK National Atmospheric Emissions Inventory. Annually averaged NH3 data from NAMN sites operational over the same period (n =  59 show an indicative downward trend, although the reduction in NH3 concentrations is smaller and non-significant: Mann–Kendall (MK, −6.3 %; linear regression (LR, −3.1 %. In areas dominated by pig and poultry farming, a significant reduction in NH3 concentrations between 1998 and 2014 (MK: −22 %; LR: −21 %, annually averaged NH3 is consistent with, but not as large as the decrease in estimated NH3 emissions from this sector over the same period (−39 %. By contrast, in cattle

  4. Long term corrosion of iron in concrete and in atmospheric conditions: a contribution of archaeological analogues to mechanism comprehension

    International Nuclear Information System (INIS)

    Burger, E.; Demoulin, A.; Dillman, Ph.; Neff, D.; Berge, P.; Burger, E.; Perrin, St.; L'hostis, V.; Dillman, Ph.; Millard, A.

    2009-01-01

    Full text of publication follows: The prediction of iron (or low alloy steel) corrosion on very long term period is necessary in two different purposes: (i) the preservation and conservation of cultural heritage and (ii) the French storage and repository concept for the radioactive wastes. In order to determine the evolution of corrosion processes for very long period, mechanistic models have been developed. In these models that are based on a phenomenological approach to evaluate the average corrosion rates, two different environments are considered: concrete (steel reinforcements) and atmospheric. The study of archaeological analogues is a very pertinent tool for the validation of these models. First, physico-chemical analysis on old corrosion layers lead to a precise localisation and identification of the phases present in the corrosion system. Moreover, experimental reinduced corrosions of ancient samples under controlled parameters (temperature, relative humidity) bring new insight on the mechanisms involved. In particular, one crucial question related to the wet-dry cycle is the localisation of oxygen reduction sites in the rust layer. For this purpose, specific experiments have been set up to re-corrode the ancient samples in marked medium (using 18 O 2 ). Samples were exposed to cycling between high and low relative humidity, produced by saline saturated solutions. Then cross-sections of samples obtained were investigated by nuclear reaction analysis (NRA) 18 O(p,α) 15 N on the Pierre Sue Laboratory nuclear microprobe. In this presentation the 18 O distribution profiles are discussed and interpreted in order to bring new insight on corrosion mechanisms. A comparative interpretation is made for each medium (concrete and atmosphere)

  5. Short-term 222Rn activity concentration changes in underground spaces with limited air exchange with the atmosphere

    Science.gov (United States)

    Fijałkowska-Lichwa, L.; Przylibski, T. A.

    2011-04-01

    The authors investigated short-time changes in 222Rn activity concentration occurring yearly in two underground tourist facilities with limited air exchange with the atmosphere. One of them is Niedźwiedzia (Bear) Cave in Kletno, Poland - a natural space equipped with locks ensuring isolation from the atmosphere. The other site is Fluorite Adit in Kletno, a section of a disused uranium mine. This adit is equipped with a mechanical ventilation system, operated periodically outside the opening times (at night). Both sites are situated within the same metamorphic rock complex, at similar altitudes, about 2 km apart. The measurements conducted revealed spring and autumn occurrence of convective air movements. In Bear Cave, this process causes a reduction in 222Rn activity concentration in the daytime, i.e. when tourists, guides and other staff are present in the cave. From the point of view of radiation protection, this is the best situation. For the rest of the year, daily concentrations of 222Rn activity in the cave are very stable. In Fluorite Adit, on the other hand, significant variations in daily 222Rn activity concentrations are recorded almost all year round. These changes are determined by the periods of activity and inactivity of mechanical ventilation. Unfortunately this is inactive in the daytime, which results in the highest values of 222Rn activity concentration at the times when tourists and staff are present in the adit. Slightly lower concentrations of radon in Fluorite Adit are recorded in the winter season, when convective air movements carry a substantial amount of radon out into the atmosphere. The incorrect usage of mechanical ventilation in Fluorite Adit results in the most unfavourable conditions in terms of radiation protection. The staff working in that facility are exposed practically throughout the year to the highest 222Rn activity concentrations, both at work (in the adit) and at home (outside their working hours). Therefore, not very well

  6. Uniqueness and reconstruction of an unknown semilinear term in a time-fractional reaction–diffusion equation

    KAUST Repository

    Luchko, Yuri

    2013-05-30

    In this paper, we consider a reaction-diffusion problem with an unknown nonlinear source function that has to be determined from overposed data. The underlying model is in the form of a time-fractional reaction-diffusion equation and the work generalizes some known results for the inverse problems posed for PDEs of parabolic type. For the inverse problem under consideration, a uniqueness result is proved and a numerical algorithm with some theoretical qualification is presented in the one-dimensional case. The key both to the uniqueness result and to the numerical algorithm relies on the maximum principle which has recently been shown to hold for the fractional diffusion equation. In order to show the effectiveness of the proposed method, results of numerical simulations are presented. © 2013 IOP Publishing Ltd.

  7. A mechanistic model for long-term nuclear waste glass dissolution integrating chemical affinity and interfacial diffusion barrier

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Teqi [Northwest Institute of Nuclear Technology, No.28 Pingyu Road, Baqiao District, Xi' an,Shaanxi, 710024 (China); Mechanics and Physics of Solids Research Group, Modelling and Simulation Centre, The University of Manchester, Oxford Road, Manchester, M13 9PL (United Kingdom); Jivkov, Andrey P., E-mail: andrey.jivkov@manchester.ac.uk [Mechanics and Physics of Solids Research Group, Modelling and Simulation Centre, The University of Manchester, Oxford Road, Manchester, M13 9PL (United Kingdom); Li, Weiping; Liang, Wei; Wang, Yu; Xu, Hui [Northwest Institute of Nuclear Technology, No.28 Pingyu Road, Baqiao District, Xi' an,Shaanxi, 710024 (China); Han, Xiaoyuan, E-mail: xyhan_nint@sina.cn [Northwest Institute of Nuclear Technology, No.28 Pingyu Road, Baqiao District, Xi' an,Shaanxi, 710024 (China)

    2017-04-01

    Understanding the alteration of nuclear waste glass in geological repository conditions is critical element of the analysis of repository retention function. Experimental observations of glass alterations provide a general agreement on the following regimes: inter-diffusion, hydrolysis process, rate drop, residual rate and, under very particular conditions, resumption of alteration. Of these, the mechanisms controlling the rate drop and the residual rate remain a subject of dispute. This paper offers a critical review of the two most competitive models related to these regimes: affinity–limited dissolution and diffusion barrier. The limitations of these models are highlighted by comparison of their predictions with available experimental evidence. Based on the comprehensive discussion of the existing models, a new mechanistic model is proposed as a combination of the chemical affinity and diffusion barrier concepts. It is demonstrated how the model can explain experimental phenomena and data, for which the existing models are shown to be not fully adequate.

  8. Long-Term, Autonomous Measurement of Atmospheric Carbon Dioxide Using an Ormosil Nanocomposite-Based Optical Sensor

    Energy Technology Data Exchange (ETDEWEB)

    Kisholoy Goswami

    2005-10-11

    The goal of this project is to construct a prototype carbon dioxide sensor that can be commercialized to offer a low-cost, autonomous instrument for long-term, unattended measurements. Currently, a cost-effective CO2 sensor system is not available that can perform cross-platform measurements (ground-based or airborne platforms such as balloon and unmanned aerial vehicle (UAV)) for understanding the carbon sequestration phenomenon. The CO2 sensor would support the research objectives of DOE-sponsored programs such as AmeriFlux and the North American Carbon Program (NACP). Global energy consumption is projected to rise 60% over the next 20 years and use of oil is projected to increase by approximately 40%. The combustion of coal, oil, and natural gas has increased carbon emissions globally from 1.6 billion tons in 1950 to 6.3 billion tons in 2000. This figure is expected to reach 10 billon tons by 2020. It is important to understand the fate of this excess CO2 in the global carbon cycle. The overall goal of the project is to develop an accurate and reliable optical sensor for monitoring carbon dioxide autonomously at least for one year at a point remote from the actual CO2 release site. In Phase I of this project, InnoSense LLC (ISL) demonstrated the feasibility of an ormosil-monolith based Autonomous Sensor for Atmospheric CO2 (ASAC) device. All of the Phase I objectives were successfully met.

  9. Mittag-Leffler synchronization of fractional neural networks with time-varying delays and reaction-diffusion terms using impulsive and linear controllers.

    Science.gov (United States)

    Stamova, Ivanka; Stamov, Gani

    2017-12-01

    In this paper, we propose a fractional-order neural network system with time-varying delays and reaction-diffusion terms. We first develop a new Mittag-Leffler synchronization strategy for the controlled nodes via impulsive controllers. Using the fractional Lyapunov method sufficient conditions are given. We also study the global Mittag-Leffler synchronization of two identical fractional impulsive reaction-diffusion neural networks using linear controllers, which was an open problem even for integer-order models. Since the Mittag-Leffler stability notion is a generalization of the exponential stability concept for fractional-order systems, our results extend and improve the exponential impulsive control theory of neural network system with time-varying delays and reaction-diffusion terms to the fractional-order case. The fractional-order derivatives allow us to model the long-term memory in the neural networks, and thus the present research provides with a conceptually straightforward mathematical representation of rather complex processes. Illustrative examples are presented to show the validity of the obtained results. We show that by means of appropriate impulsive controllers we can realize the stability goal and to control the qualitative behavior of the states. An image encryption scheme is extended using fractional derivatives. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Modeling long-term leaching experiments of full scale cemented wastes: effect of solution composition on diffusion

    International Nuclear Information System (INIS)

    Borkel, C.; Montoya, V.; Kienzler, B.

    2015-01-01

    The code PHREECQ V3.1 has been used to simulate leaching experiments performed with cemented simulated waste products in tap water for more than 30 years. In this work the main focus is related with the leaching of Cs explained by diffusion processes. A simplifying model using the code PHREECQ V3.1 was used to investigate the influence of different parameters on the release of Cs from the cement solid to the leaching solution. The model setup bases on four main assumptions: a) the solid as well as the distribution of Cs is homogeneous and of isotropic texture, b) there is no preferential direction regarding cement degradation or water intrusion into the solid, c) the pore space is entirely connected and d) Cs adsorption to the cement or container is negligible. In the modeling the constraint of charge balance was stressed. Effective diffusion coefficients (D e ) were obtained analytically and from modeling the diffusive release of Cs from cemented waste simulates. The obtained values D e for Cs leaching are in perfect agreement with the values published in literature. Contradictory results to diffusive release were obtained from XRD analysis of the solids, suggesting that water may not have penetrated the cement monoliths entirely, but only to some centimeters depth. XRD analysis have been done to determine the solid phases present in cement and are used to help outlining strength and weaknesses of the different models

  11. Uniqueness for inverse problems of determining orders of multi-term time-fractional derivatives of diffusion equation

    OpenAIRE

    Li, Zhiyuan; Yamamoto, Masahiro

    2014-01-01

    This article proves the uniqueness for two kinds of inverse problems of identifying fractional orders in diffusion equations with multiple time-fractional derivatives by pointwise observation. By means of eigenfunction expansion and Laplace transform, we reduce the uniqueness for our inverse problems to the uniqueness of expansions of some special function and complete the proof.

  12. Fungal community composition and function after long-term exposure of northern forests to elevated atmospheric CO2 and tropospheric O3

    Science.gov (United States)

    Ivan P. Edwards; Donald R. Zak

    2011-01-01

    The long-term effects of rising atmospheric carbon dioxide (CO2) and tropospheric O3 concentrations on fungal communities in soil are not well understood. Here, we examine fungal community composition and the activities of cellobiohydrolase and N-acetylglucosaminidase (NAG) after 10 years of exposure to 1...

  13. Diffusion bonding

    International Nuclear Information System (INIS)

    Anderson, R.C.

    1976-01-01

    A method is described for joining beryllium to beryllium by diffusion bonding. At least one surface portion of at least two beryllium pieces is coated with nickel. A coated surface portion is positioned in a contiguous relationship with another surface portion and subjected to an environment having an atmosphere at a pressure lower than ambient pressure. A force is applied on the beryllium pieces for causing the contiguous surface portions to abut against each other. The contiguous surface portions are heated to a maximum temperature less than the melting temperature of the beryllium, and the applied force is decreased while increasing the temperature after attaining a temperature substantially above room temperature. A portion of the applied force is maintained at a temperature corresponding to about maximum temperature for a duration sufficient to effect the diffusion bond between the contiguous surface portions

  14. North Atlantic atmospheric circulation and surface wind in the Northeast of the Iberian Peninsula: uncertainty and long term downscaled variability

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Bustamante, E.; Jimenez, P.A. [CIEMAT, Departamento de Energias Renovables, Madrid (Spain); Universidad Complutense de Madrid, Departamento de Astrofisica y CC. de la Atmosfera, Madrid (Spain); Gonzalez-Rouco, J.F. [Universidad Complutense de Madrid, Departamento de Astrofisica y CC. de la Atmosfera, Madrid (Spain); Navarro, J. [CIEMAT, Departamento de Energias Renovables, Madrid (Spain); Xoplaki, E. [University of Bern, Institute of Geography and Oeschger Centre for Climate Change Research, Bern (Switzerland); Montavez, J.P. [Universidad de Murcia, Departamento de Fisica, Murcia (Spain)

    2012-01-15

    The variability and predictability of the surface wind field at the regional scale is explored over a complex terrain region in the northeastern Iberian Peninsula by means of a downscaling technique based on Canonical Correlation Analysis. More than a decade of observations (1992-2005) allows for calibrating and validating a statistical method that elicits the main associations between the large scale atmospheric circulation over the North Atlantic and Mediterranean areas and the regional wind field. In an initial step the downscaling model is designed by selecting parameter values from practise. To a large extent, the variability of the wind at monthly timescales is found to be governed by the large scale circulation modulated by the particular orographic features of the area. The sensitivity of the downscaling methodology to the selection of the model parameter values is explored, in a second step, by performing a systematic sampling of the parameters space, avoiding a heuristic selection. This provides a metric for the uncertainty associated with the various possible model configurations. The uncertainties associated with the model configuration are considerably dependent on the spatial variability of the wind. While the sampling of the parameters space in the model set up moderately impact estimations during the calibration period, the regional wind variability is very sensitive to the parameters selection at longer timescales. This fact illustrates that downscaling exercises based on a single configuration of parameters should be interpreted with extreme caution. The downscaling model is used to extend the estimations several centuries to the past using long datasets of sea level pressure, thereby illustrating the large temporal variability of the regional wind field from interannual to multicentennial timescales. The analysis does not evidence long term trends throughout the twentieth century, however anomalous episodes of high/low wind speeds are identified

  15. Photosynthetic responses of yellow poplar and white oak to long term atmospheric CO2 enrichment in the field

    International Nuclear Information System (INIS)

    Gunderson, C.A.; Norby, R.J.

    1991-01-01

    A critical consideration in evaluating forest response to rising atmospheric CO 2 is whether the enhancement of net photosynthesis (P N ) by elevated CO 2 can be sustained over the long term. There are reports of declining enhancement of P N with duration of exposure to elevated CO 2 , associated with decreases in photosynthetic capacity and carboxylation efficiency. We investigated whether this photosynthetic acclimation occurs in two tree species under field conditions. Seedlings of yellow-poplar (Liriodendron tulipifera L.) and white oak (Quercus alba L.) were planted in the ground within six open-top field chambers in May 1989 and have been exposed continuously to CO 2 enrichment during the last two growing seasons. The three CO 2 treatment levels were: ambient, ambient +150, and ambient +300 μL/L. Throughout the second season, gas exchange of upper, light-saturated leaves was surveyed periodically, and leaves of different ages and canopy positions were measured occasionally. Net photosynthesis remained higher at higher CO 2 levels (28-32% higher in +150 and 49-67% higher in +300 seedlings) in both species throughout the season, regardless of increasing leaf age and duration of exposure to CO 2 enrichment. Stomatal conductance remained unchanged or decreased slightly with increasing CO 2 , but instantaneous water use efficiency (P N /transpiration) increased significantly with CO 2 . Analysis of P N versus internal CO 2 concentration indicated no significant treatment differences in carboxylation efficiency, CO 2 -saturated P N , or CO 2 compensation point. There was no evidence of a downward acclimation of photosynthesis to CO 2 enrichment in this system

  16. Xenon-133 and caesium-137 releases into the atmosphere from the Fukushima Dai-ichi nuclear power plant: determination of the source term, atmospheric dispersion, and deposition

    Science.gov (United States)

    Stohl, A.; Seibert, P.; Wotawa, G.; Arnold, D.; Burkhart, J. F.; Eckhardt, S.; Tapia, C.; Vargas, A.; Yasunari, T. J.

    2012-04-01

    This presentation will show the results of a paper currently under review in ACPD and some additional new results, including more data and with an independent box modeling approach to support some of the findings of the ACPD paper. On 11 March 2011, an earthquake occurred about 130 km off the Pacific coast of Japan's main island Honshu, followed by a large tsunami. The resulting loss of electric power at the Fukushima Dai-ichi nuclear power plant (FD-NPP) developed into a disaster causing massive release of radioactivity into the atmosphere. In this study, we determine the emissions of two isotopes, the noble gas xenon-133 (133Xe) and the aerosol-bound caesium-137 (137Cs), which have very different release characteristics as well as behavior in the atmosphere. To determine radionuclide emissions as a function of height and time until 20 April, we made a first guess of release rates based on fuel inventories and documented accident events at the site. This first guess was subsequently improved by inverse modeling, which combined the first guess with the results of an atmospheric transport model, FLEXPART, and measurement data from several dozen stations in Japan, North America and other regions. We used both atmospheric activity concentration measurements as well as, for 137Cs, measurements of bulk deposition. Regarding 133Xe, we find a total release of 16.7 (uncertainty range 13.4-20.0) EBq, which is the largest radioactive noble gas release in history not associated with nuclear bomb testing. There is strong evidence that the first strong 133Xe release started early, before active venting was performed. The entire noble gas inventory of reactor units 1-3 was set free into the atmosphere between 11 and 15 March 2011. For 137Cs, the inversion results give a total emission of 35.8 (23.3-50.1) PBq, or about 42% of the estimated Chernobyl emission. Our results indicate that 137Cs emissions peaked on 14-15 March but were generally high from 12 until 19 March, when they

  17. Long-Term Follow-up of a Patient with Traumatic Brain Injury Using Diffusion Tensor Imaging

    Energy Technology Data Exchange (ETDEWEB)

    Skoglund, T.S.; Nilsson, D.; Ljungberg, M.; Joensson, L.; Rydenhag, B. (Dept. of Neurosurgery, Dept. of Medical Physics and Biomedical Engineering, and Dept. of Radiology, Sahlgrenska Univ. Hospital, Goeteborg (Sweden))

    2008-02-15

    This case report describes a patient who sustained severe head trauma with diffuse axonal injury (DAI). Examination with magnetic resonance diffusion tensor imaging (MR-DTI), 6 days post-injury, showed a severe reduction in fractional anisotropy (FA) in the rostral pons containing the corticospinal tract, which correlated to the patient's severe hemiparesis. By 18 months post-accident, the patient had recovered completely and conventional MRI showed no pathology. However, although her FA values in the rostral pons had increased, they were still not normalized. It seems that a complete normalization of the FA values is not required to achieve clinical recovery, and that MR-DTI seems to be more sensitive to DAI compared to conventional MRI

  18. Long-Term Follow-up of a Patient with Traumatic Brain Injury Using Diffusion Tensor Imaging

    International Nuclear Information System (INIS)

    Skoglund, T.S.; Nilsson, D.; Ljungberg, M.; Joensson, L.; Rydenhag, B.

    2008-01-01

    This case report describes a patient who sustained severe head trauma with diffuse axonal injury (DAI). Examination with magnetic resonance diffusion tensor imaging (MR-DTI), 6 days post-injury, showed a severe reduction in fractional anisotropy (FA) in the rostral pons containing the corticospinal tract, which correlated to the patient's severe hemiparesis. By 18 months post-accident, the patient had recovered completely and conventional MRI showed no pathology. However, although her FA values in the rostral pons had increased, they were still not normalized. It seems that a complete normalization of the FA values is not required to achieve clinical recovery, and that MR-DTI seems to be more sensitive to DAI compared to conventional MRI

  19. Diffusion tensor imaging for long-term follow-up of corticospinal tract degeneration in amyotrophic lateral sclerosis

    Energy Technology Data Exchange (ETDEWEB)

    Jacob, S.; Ehrenreich, H. [Max-Planck-Institute for Experimental Medicine, Georg-August-University, Hermann-Rein-Strasse 3, 37075, Goettingen (Germany); Departments of Neurology and Psychiatry, Georg-August-University, Goettingen (Germany); Finsterbusch, J.; Frahm, J. [Biomedizinische NMR Forschungs GmbH, Max-Planck-Institute for Biophysical Chemistry, Georg-August-University, Goettingen (Germany); Weishaupt, J.H. [Departments of Neurology and Psychiatry, Georg-August-University, Goettingen (Germany); Khorram-Sefat, D. [Department of Neuroradiology, Georg-August-University, Goettingen (Germany)

    2003-09-01

    Amyotrophic lateral sclerosis (ALS) is a predominantly clinical and electromyographic diagnosis. Conventional MRI reveals atrophy of the motor system, particularly the pyramidal tract, in the advanced stages but does not provide a sensitive measure of disease progression. Three patients with different principal symptoms of ALS, i.e., with predominant involvement of the upper (UMN) or lower (UMN) motor neurons, or bulbar disease, respectively, underwent serial clinical examination including lung function tests, conventional MRI, and diffusion tensor imaging (DTI). MRI demonstrated changes in of the pyramidal tract without measurable variation on follow-up. The patient with UMN involvement showed remarkable progressive loss of diffusion anisotropy in the pyramidal tract. DTI might be useful, together with clinical follow-up, as an objective morphological marker in therapeutic trials. (orig.)

  20. Source term assessment, containment atmosphere control systems, and accident consequences. Report to CSNI by an OECD/NEA Group of experts

    International Nuclear Information System (INIS)

    1987-04-01

    CSNI Report 135 summarizes the results of the work performed by CSNI's Principal Working Group No. 4 on the Source Term and Environmental Consequences (PWG4) during the period extending from 1983 to 1986. This document contains the latest information on some important topics relating to source terms, accident consequence assessment, and containment atmospheric control systems. It consists of five parts: (1) a Foreword and Executive Summary prepared by PWG4's Chairman; (2) a Report on the Technical Status of the Source Term; (3) a Report on the Technical Status of Filtration and Containment Atmosphere Control Systems for Nuclear Reactors in the Event of a Severe Accident; (4) a Report on the Technical Status of Reactor Accident Consequence Assessment; (5) a list of members of PWG4

  1. Diffusion archeology for diffusion progression history reconstruction.

    Science.gov (United States)

    Sefer, Emre; Kingsford, Carl

    2016-11-01

    Diffusion through graphs can be used to model many real-world processes, such as the spread of diseases, social network memes, computer viruses, or water contaminants. Often, a real-world diffusion cannot be directly observed while it is occurring - perhaps it is not noticed until some time has passed, continuous monitoring is too costly, or privacy concerns limit data access. This leads to the need to reconstruct how the present state of the diffusion came to be from partial diffusion data. Here, we tackle the problem of reconstructing a diffusion history from one or more snapshots of the diffusion state. This ability can be invaluable to learn when certain computer nodes are infected or which people are the initial disease spreaders to control future diffusions. We formulate this problem over discrete-time SEIRS-type diffusion models in terms of maximum likelihood. We design methods that are based on submodularity and a novel prize-collecting dominating-set vertex cover (PCDSVC) relaxation that can identify likely diffusion steps with some provable performance guarantees. Our methods are the first to be able to reconstruct complete diffusion histories accurately in real and simulated situations. As a special case, they can also identify the initial spreaders better than the existing methods for that problem. Our results for both meme and contaminant diffusion show that the partial diffusion data problem can be overcome with proper modeling and methods, and that hidden temporal characteristics of diffusion can be predicted from limited data.

  2. Long Term Sorption Diffusion Experiment (LTDE-SD). Supporting laboratory program - Sorption diffusion experiments and rock material characterisation. With supplement of adsorption studies on intact rock samples from the Forsmark and Laxemar site investigations

    Energy Technology Data Exchange (ETDEWEB)

    Widestrand, Henrik; Byegaard, Johan; Selnert, Eva; Skaalberg, Mats; Hoeglund, Susanne; Gustafsson, Erik (Geosigma AB, Uppsala (Sweden))

    2010-12-15

    The LTDE-SD experiment, (Long Term Sorption Diffusion Experiment) aims at increasing the scientific knowledge of sorption and diffusion under in situ conditions and to provide data for performance and safety assessment calculations. In this report, performance and results of laboratory sorption and diffusion experiments and porosity investigations using site-specific crushed and intact rock materials are presented, including a geological and mineralogical characterization of the samples. A synthetic groundwater and a part of the radionuclide tracer cocktail that was used for the in situ experiment were used also in the laboratory experiments. 13 radionuclide tracers were analysed in the laboratory experiments. The method descriptions from SKB Site Investigations were applied in order to enable comparisons with Site Investigations data. The water saturation porosity of 10 unaltered matrix rock samples from KA3065A02 and A03 is 0.26 +- 0.08% and two fracture material samples show porosities of 2.4% and 5.2% respectively. 14C-methylmethacrylate impregnation (the PMMA-method) show that the unaltered rock matrix porosity is relatively homogeneous with grain boundary porosity, while the porosity of fracture samples is heterogeneous and have increased porosity up to more than 10% in some parts. Through-diffusion experiments using tritiated water (H3HO) give a matrix diffusivity in the range from 2.7centre dot10-14 to 6.5centre dot10-14 m2/s in four samples from KA3065A02 and A03. The results of the porosity and diffusion measurements are coherent in ranges with earlier LTDE-SD measurements and are also in line with the SKB Site Investigations results. In the batch sorption experiments using crushed rock material, two matrix rock samples of Aevroe granodiorite, one red-stained altered Aevroe granodiorite sample and two chlorite-calcite dominated fracture samples were analysed for three different size fractions as a function of time up to 186 days contact time. The

  3. Diffuse excessive high signal intensity in low-risk preterm infants at term-equivalent age does not predict outcome at 1 year: a prospective study

    Energy Technology Data Exchange (ETDEWEB)

    Leitner, Yael [Tel Aviv Sourasky Medical Centre, Child Development Centre, Dana-Dwek Children' s Hospital, Tel Aviv (Israel); Tel Aviv University, Sackler Faculty of Medicine, Tel Aviv (Israel); Weinstein, Maya [Tel Aviv Sourasky Medical Centre, Functional Brain Centre, The Wohl Institute for Advanced Imaging, Tel Aviv (Israel); Bar Ilan University, Department of Psychology, Gonda Multidisciplinary Brain Research Centre, Ramat-Gan (Israel); Myers, Vicki [Tel Aviv Sourasky Medical Centre, Functional Brain Centre, The Wohl Institute for Advanced Imaging, Tel Aviv (Israel); Uliel, Shimrit; Geva, Karen [Tel Aviv Sourasky Medical Centre, Child Development Centre, Dana-Dwek Children' s Hospital, Tel Aviv (Israel); Berger, Irit; Marom, Ronella [Tel Aviv Sourasky Medical Centre, Department of Neonatology, Lis Maternity Hospital, Tel Aviv (Israel); Tel Aviv University, Sackler Faculty of Medicine, Tel Aviv (Israel); Bashat, Dafna Ben [Tel Aviv University, Sackler Faculty of Medicine, Tel Aviv (Israel); Tel Aviv University, Sagol School of Neuroscience, Tel Aviv (Israel); Ben-Sira, Liat [Tel Aviv University, Sackler Faculty of Medicine, Tel Aviv (Israel); Tel Aviv Sourasky Medical Centre, Department of Radiology, Tel Aviv (Israel); Geva, Ronny [Bar Ilan University, Department of Psychology, Gonda Multidisciplinary Brain Research Centre, Ramat-Gan (Israel); Gross-Tsur, Varda [Shaare-Zedek Medical Centre, Neuropediatric Unit, Jerusalem (Israel)

    2014-08-15

    The outcome of premature infants with only diffuse excessive high signal intensity (DEHSI) is not clear. We explored the relationship between DEHSI, white matter (WM) diffusion characteristics, perinatal characteristics, and neurobehavioral outcome at 1 year in a homogenous group of preterm infants without major brain abnormalities. Fifty-eight preterm infants, gestational age 29 ± 2.6 weeks, underwent an MRI at term-equivalent age (TEA). Griffiths Mental Developmental Scales, neurological assessment, and Parental Stress Index (PSI) were performed at 1 year corrected age. These measures were compared between preterm infants according to DEHSI classification (none, mild, moderate). Diffusion tensor imaging was used in major WM volumes of interest to objectively measure the degree of WM maturation. No significant differences were detected in the perinatal risk characteristics, neurobehavioral outcome, and PSI at 1 year between infants with different DEHSI classifications. In infants with DEHSI, increased axial and radial diffusivities were detected in the optic radiations, centrum semiovale, and posterior limb of the internal capsule, indicating less advanced maturation of the WM. Significant correlations were detected between the time interval from birth to MRI and the WM microstructure in infants without DEHSI. DEHSI in premature infants is neither a predictive measure for short-term adverse neurobehavioral outcome nor related to perinatal risk characteristics. Extrauterine exposure time had a differential effect on WM maturational trajectories in infants with DEHSI compared to those without. We suggest DEHSI may represent an alteration in WM maturational characteristics. Further follow-up studies may verify later consequences of DEHSI in premature infants. (orig.)

  4. Diffuse excessive high signal intensity in low-risk preterm infants at term-equivalent age does not predict outcome at 1 year: a prospective study

    International Nuclear Information System (INIS)

    Leitner, Yael; Weinstein, Maya; Myers, Vicki; Uliel, Shimrit; Geva, Karen; Berger, Irit; Marom, Ronella; Bashat, Dafna Ben; Ben-Sira, Liat; Geva, Ronny; Gross-Tsur, Varda

    2014-01-01

    The outcome of premature infants with only diffuse excessive high signal intensity (DEHSI) is not clear. We explored the relationship between DEHSI, white matter (WM) diffusion characteristics, perinatal characteristics, and neurobehavioral outcome at 1 year in a homogenous group of preterm infants without major brain abnormalities. Fifty-eight preterm infants, gestational age 29 ± 2.6 weeks, underwent an MRI at term-equivalent age (TEA). Griffiths Mental Developmental Scales, neurological assessment, and Parental Stress Index (PSI) were performed at 1 year corrected age. These measures were compared between preterm infants according to DEHSI classification (none, mild, moderate). Diffusion tensor imaging was used in major WM volumes of interest to objectively measure the degree of WM maturation. No significant differences were detected in the perinatal risk characteristics, neurobehavioral outcome, and PSI at 1 year between infants with different DEHSI classifications. In infants with DEHSI, increased axial and radial diffusivities were detected in the optic radiations, centrum semiovale, and posterior limb of the internal capsule, indicating less advanced maturation of the WM. Significant correlations were detected between the time interval from birth to MRI and the WM microstructure in infants without DEHSI. DEHSI in premature infants is neither a predictive measure for short-term adverse neurobehavioral outcome nor related to perinatal risk characteristics. Extrauterine exposure time had a differential effect on WM maturational trajectories in infants with DEHSI compared to those without. We suggest DEHSI may represent an alteration in WM maturational characteristics. Further follow-up studies may verify later consequences of DEHSI in premature infants. (orig.)

  5. Xenon-133 and caesium-137 releases into the atmosphere from the Fukushima Dai-ichi nuclear power plant. Determination of the source term, atmospheric dispersion, and deposition

    International Nuclear Information System (INIS)

    Stohl, A.; Burkhart, J.F.; Eckhardt, S.; Seibert, P.; Arnold, D.; Technical Univ. of Catalonia, Barcelona; Tapia, C.; Vargas, A.; Yasunari, T.J.

    2012-01-01

    On 11 March 2011, an earthquake occurred about 130 km off the Pacific coast of Japan's main island Honshu, followed by a large tsunami. The resulting loss of electric power at the Fukushima Dai-ichi nuclear power plant developed into a disaster causing massive release of radioactivity into the atmosphere. In this study, we determine the emissions into the atmosphere of two isotopes, the noble gas xenon-133 ("1"3"3Xe) and the aerosol-bound caesium-137 ("1"3"7Cs), which have very different release characteristics as well as behavior in the atmosphere. To determine radionuclide emissions as a function of height and time until 20 April, we made a first guess of release rates based on fuel inventories and documented accident events at the site. This first guess was subsequently improved by inverse modeling, which combined it with the results of an atmospheric transport model, FLEXPART, and measurement data from several dozen stations in Japan, North America and other regions. We used both atmospheric activity concentration measurements as well as, for "1"3"7Cs, measurements of bulk deposition. Regarding "1"3"3Xe, we find a total release of 15.3 (uncertainty range 12.2-18.3) EBq, which is more than twice as high as the total release from Chernobyl and likely the largest radioactive noble gas release in history. The entire noble gas inventory of reactor units 1-3 was set free into the atmosphere between 11 and 15 March 2011. In fact, our release estimate is higher than the entire estimated "1"3"3Xe inventory of the Fukushima Dai-ichi nuclear power plant, which we explain with the decay of iodine-133 (half-life of 20.8 h) into "1"3"3Xe. There is strong evidence that the "1"3"3Xe release started before the first active venting was made, possibly indicating structural damage to reactor components and/or leaks due to overpressure which would have allowed early release of noble gases. For "1"3"7Cs, the inversion results give a total emission of 36.6 (20.1-53.1) PBq, or about

  6. Xenon-133 and caesium-137 releases into the atmosphere from the Fukushima Dai-ichi nuclear power plant: determination of the source term, atmospheric dispersion, and deposition

    Directory of Open Access Journals (Sweden)

    A. Stohl

    2012-03-01

    Full Text Available On 11 March 2011, an earthquake occurred about 130 km off the Pacific coast of Japan's main island Honshu, followed by a large tsunami. The resulting loss of electric power at the Fukushima Dai-ichi nuclear power plant developed into a disaster causing massive release of radioactivity into the atmosphere. In this study, we determine the emissions into the atmosphere of two isotopes, the noble gas xenon-133 (133Xe and the aerosol-bound caesium-137 (137Cs, which have very different release characteristics as well as behavior in the atmosphere. To determine radionuclide emissions as a function of height and time until 20 April, we made a first guess of release rates based on fuel inventories and documented accident events at the site. This first guess was subsequently improved by inverse modeling, which combined it with the results of an atmospheric transport model, FLEXPART, and measurement data from several dozen stations in Japan, North America and other regions. We used both atmospheric activity concentration measurements as well as, for 137Cs, measurements of bulk deposition. Regarding 133Xe, we find a total release of 15.3 (uncertainty range 12.2–18.3 EBq, which is more than twice as high as the total release from Chernobyl and likely the largest radioactive noble gas release in history. The entire noble gas inventory of reactor units 1–3 was set free into the atmosphere between 11 and 15 March 2011. In fact, our release estimate is higher than the entire estimated 133Xe inventory of the Fukushima Dai-ichi nuclear power plant, which we explain with the decay of iodine-133 (half-life of 20.8 h into 133Xe. There is strong evidence that the 133Xe release started before the first active venting was made, possibly indicating structural damage to reactor components and/or leaks due to overpressure which would have allowed early release of noble gases. For 137

  7. Xenon-133 and caesium-137 releases into the atmosphere from the Fukushima Dai-ichi nuclear power plant. Determination of the source term, atmospheric dispersion, and deposition

    Energy Technology Data Exchange (ETDEWEB)

    Stohl, A.; Burkhart, J.F.; Eckhardt, S. [NILU - Norwegian Institute for Air Research, Kjeller (Norway); Seibert, P. [Univ. of Natural Resources and Life Sciences, Vienna (Austria). Inst. of Meteorology; Wotawa, G. [Central Institute for Meteorology and Geodynamics, Vienna (Austria); Arnold, D. [Univ. of Natural Resources and Life Sciences, Vienna (Austria). Inst. of Meteorology; Technical Univ. of Catalonia, Barcelona (Spain). Inst. of Energy Technologies; Tapia, C. [Technical Univ. of Catalonia, Barcelona (Spain). Dept. of Physics and Nucelar Engineering; Vargas, A. [Technical Univ. of Catalonia, Barcelona (Spain). Inst. of Energy Technologies; Yasunari, T.J. [Univs. Space Research Association, Columbia, MD (United States). Goddard Earth Sciences and Technology and Research

    2012-07-01

    On 11 March 2011, an earthquake occurred about 130 km off the Pacific coast of Japan's main island Honshu, followed by a large tsunami. The resulting loss of electric power at the Fukushima Dai-ichi nuclear power plant developed into a disaster causing massive release of radioactivity into the atmosphere. In this study, we determine the emissions into the atmosphere of two isotopes, the noble gas xenon-133 ({sup 133}Xe) and the aerosol-bound caesium-137 ({sup 137}Cs), which have very different release characteristics as well as behavior in the atmosphere. To determine radionuclide emissions as a function of height and time until 20 April, we made a first guess of release rates based on fuel inventories and documented accident events at the site. This first guess was subsequently improved by inverse modeling, which combined it with the results of an atmospheric transport model, FLEXPART, and measurement data from several dozen stations in Japan, North America and other regions. We used both atmospheric activity concentration measurements as well as, for {sup 137}Cs, measurements of bulk deposition. Regarding {sup 133}Xe, we find a total release of 15.3 (uncertainty range 12.2-18.3) EBq, which is more than twice as high as the total release from Chernobyl and likely the largest radioactive noble gas release in history. The entire noble gas inventory of reactor units 1-3 was set free into the atmosphere between 11 and 15 March 2011. In fact, our release estimate is higher than the entire estimated {sup 133}Xe inventory of the Fukushima Dai-ichi nuclear power plant, which we explain with the decay of iodine-133 (half-life of 20.8 h) into {sup 133}Xe. There is strong evidence that the {sup 133}Xe release started before the first active venting was made, possibly indicating structural damage to reactor components and/or leaks due to overpressure which would have allowed early release of noble gases. For {sup 137}Cs, the inversion results give a total emission of 36

  8. Detailed source term estimation of the atmospheric release for the Fukushima Daiichi Nuclear Power Station accident by coupling simulations of an atmospheric dispersion model with an improved deposition scheme and oceanic dispersion model

    Energy Technology Data Exchange (ETDEWEB)

    Katata, G.; Chino, M.; Kobayashi, T. [Japan Atomic Energy Agency (JAEA), Ibaraki (Japan); and others

    2015-07-01

    Temporal variations in the amount of radionuclides released into the atmosphere during the Fukushima Daiichi Nuclear Power Station (FNPS1) accident and their atmospheric and marine dispersion are essential to evaluate the environmental impacts and resultant radiological doses to the public. In this paper, we estimate the detailed atmospheric releases during the accident using a reverse estimation method which calculates the release rates of radionuclides by comparing measurements of air concentration of a radionuclide or its dose rate in the environment with the ones calculated by atmospheric and oceanic transport, dispersion and deposition models. The atmospheric and oceanic models used are WSPEEDI-II (Worldwide version of System for Prediction of Environmental Emergency Dose Information) and SEA-GEARN-FDM (Finite difference oceanic dispersion model), both developed by the authors. A sophisticated deposition scheme, which deals with dry and fog-water depositions, cloud condensation nuclei (CCN) activation, and subsequent wet scavenging due to mixed-phase cloud microphysics (in-cloud scavenging) for radioactive iodine gas (I{sub 2} and CH{sub 3}I) and other particles (CsI, Cs, and Te), was incorporated into WSPEEDI-II to improve the surface deposition calculations. The results revealed that the major releases of radionuclides due to the FNPS1 accident occurred in the following periods during March 2011: the afternoon of 12 March due to the wet venting and hydrogen explosion at Unit 1, midnight of 14 March when the SRV (safety relief valve) was opened three times at Unit 2, the morning and night of 15 March, and the morning of 16 March. According to the simulation results, the highest radioactive contamination areas around FNPS1 were created from 15 to 16 March by complicated interactions among rainfall, plume movements, and the temporal variation of release rates. The simulation by WSPEEDI-II using the new source term reproduced the local and regional patterns of

  9. Long-term increase in diffuse groundwater recharge following expansion of rainfed cultivation in the Sahel, West Africa

    Science.gov (United States)

    Ibrahim, Maïmouna; Favreau, Guillaume; Scanlon, Bridget R.; Seidel, Jean Luc; Le Coz, Mathieu; Demarty, Jérôme; Cappelaere, Bernard

    2014-09-01

    Rapid population growth in sub-Saharan West Africa and related cropland expansion were shown in some places to have increased focused recharge through ponds, raising the water table. To estimate changes in diffuse recharge, the water content and matric potential were monitored during 2009 and 2010, and modeling was performed using the Hydrus-1D code for two field sites in southwest Niger: (1) fallow land and (2) rainfed millet cropland. Monitoring results of the upper 10 m showed increased water content and matric potential to greater depth under rainfed cropland (>2.5 m) than under fallow land (≤1.0 m). Model simulations indicate that conversion from fallow land to rainfed cropland (1) increases vadose-zone water storage and (2) should increase drainage flux (˜25 mm year-1) at 10-m depth after a 30-60 year lag. Therefore, observed regional increases in groundwater storage may increasingly result from diffuse recharge, which could compensate, at least in part, groundwater withdrawal due to observed expansion in irrigated surfaces; and hence, contribute to mitigate food crises in the Sahel.

  10. Long term change in atmospheric dust absorption, dust scattering and black carbon aerosols scattering coefficient parameters over western Indian locations

    Science.gov (United States)

    Satoliya, Anil Kumar; Vyas, B. M.; Shekhawat, M. S.

    2018-05-01

    The first time satellite space based measurement of atmospheric black carbon (BC) aerosols scattering coefficient at 550nm (BC SC at 550nm), dust aerosols scattering and dust aerosols extinction coefficient (DSC at 550nm and DEC at 550nm) parameters have been used to understand their long term trend of natural and anthropogenic aerosols behavior with its close association with ground based measured precipitation parameters such as Total Rain Fall (TRF), and Total Number of Rainy Days (TNRD) for the same period over western Indian regions concerned to the primary aerosols sources of natural activities. The basic objective of this study is an attempt to investigate the inter-correlation between dust and black carbon aerosols loading characteristics with a variation of rainfall pattern parameters as indirect aerosols induced effect i.e., aerosols-cloud interaction. The black carbon aerosols generated by diverse anthropogenic or human made activities are studied by choosing of measured atmospheric BC SC at 550nm parameter, whereas desert dust mineral aerosols primarily produced by varieties of natural activities pre-dominated of dust mineral desert aerosols mainly over Thar desert influenced area of hot climate and rural tropical site are investigated by selecting DSC at 550nm and DEC at 550nm of first semi-urban site i.e., Udaipur (UDP, 24.6°N, 73.35°E, 580m above surface level (asl)) situated in southern Rajasthan part as well as over other two Great Indian Thar desert locations i.e., Jaisalmer (JSM, 26.90°N, 69.90°E, 220m asl)) and Bikaner (BKN, 28.03°N, 73.30°E, 224m asl) located in the vicinity of the Thar desert region situated in Rajasthan state of the western Indian region. The source of the present study would be collection of longer period of monthly values of the above parameters of spanning 35 years i.e., 1980 to 2015. Such types of atmospheric aerosols-cloud monsoon interaction investigation is helpful in view of understanding their direct and

  11. A long-term time series of global and diffuse photosynthetically active radiation in the Mediterranean: interannual variability and cloud effects

    Directory of Open Access Journals (Sweden)

    P. Trisolino

    2018-06-01

    Full Text Available Measurements of global and diffuse photosynthetically active radiation (PAR have been carried out on the island of Lampedusa, in the central Mediterranean Sea, since 2002. PAR is derived from observations made with multi-filter rotating shadowband radiometers (MFRSRs by comparison with a freshly calibrated PAR sensor and by relying on the on-site Langley plots. In this way, a long-term calibrated record covering the period 2002–2016 is obtained and is presented in this work. The monthly mean global PAR peaks in June, with about 160 W m−2, while the diffuse PAR reaches 60 W m−2 in spring or summer. The global PAR displays a clear annual cycle with a semi amplitude of about 52 W m−2. The diffuse PAR annual cycle has a semi amplitude of about 12 W m−2. A simple method to retrieve the cloud-free PAR global and diffuse irradiances in days characterized by partly cloudy conditions has been implemented and applied to the dataset. This method allows retrieval of the cloud-free evolution of PAR and calculation of the cloud radiative effect, CRE, for downwelling PAR. The cloud-free monthly mean global PAR reaches 175 W m−2 in summer, while the diffuse PAR peaks at about 40 W m−2. The cloud radiative effect, CRE, on global and diffuse PAR is calculated as the difference between all-sky and cloud-free measurements. The annual average CRE is about −14.7 W m−2 for the global PAR and +8.1 W m−2 for the diffuse PAR. The smallest CRE is observed in July, due to the high cloud-free condition frequency. Maxima (negative for the global, and positive for the diffuse component occur in March–April and in October, due to the combination of elevated PAR irradiances and high occurrence of cloudy conditions. Summer clouds appear to be characterized by a low frequency of occurrence, low altitude, and low optical thickness, possibly linked to the peculiar marine boundary layer structure. These properties also contribute

  12. Potential long-term effects of MDMA on the basal ganglia-thalamocortical circuit: a proton MR spectroscopy and diffusion-tensor imaging study.

    Science.gov (United States)

    Liu, Hua-Shan; Chou, Ming-Chung; Chung, Hsiao-Wen; Cho, Nai-Yu; Chiang, Shih-Wei; Wang, Chao-Ying; Kao, Hung-Wen; Huang, Guo-Shu; Chen, Cheng-Yu

    2011-08-01

    To investigate the effects of 3,4-methylenedioxymethamphetamine (MDMA, commonly known as "ecstasy") on the alterations of brain metabolites and anatomic tissue integrity related to the function of the basal ganglia-thalamocortical circuit by using proton magnetic resonance (MR) spectroscopy and diffusion-tensor MR imaging. This study was approved by a local institutional review board, and written informed consent was obtained from all subjects. Thirty-one long-term (>1 year) MDMA users and 33 healthy subjects were enrolled. Proton MR spectroscopy from the middle frontal cortex and bilateral basal ganglia and whole-brain diffusion-tensor MR imaging were performed with a 3.0-T system. Absolute concentrations of metabolites were computed, and diffusion-tensor data were registered to the International Consortium for Brain Mapping template to facilitate voxel-based group comparison. The mean myo-inositol level in the basal ganglia of MDMA users (left: 4.55 mmol/L ± 2.01 [standard deviation], right: 4.48 mmol/L ± 1.33) was significantly higher than that in control subjects (left: 3.25 mmol/L ± 1.30, right: 3.31 mmol/L ± 1.19) (P 50 voxels). Increased myo-inositol and Cho concentrations in the basal ganglia of MDMA users are suggestive of glial response to degenerating serotonergic functions. The abnormal metabolic changes in the basal ganglia may consequently affect the inhibitory effect of the basal ganglia to the thalamus, as suggested by the increased FA in the thalamus and abnormal changes in water diffusion in the corresponding basal ganglia-thalamocortical circuit. © RSNA, 2011.

  13. Long-term mortality study of workers occupationally exposed to metallic nickel at the Oak Ridge Gaseous Diffusion Plant

    International Nuclear Information System (INIS)

    Godbold, J.H. Jr.; Tompkins, E.A.

    1979-01-01

    This study was undertaken to determine whether mortality from respiratory cancer among workers occupationally exposed to metallic nickel at the Oak Ridge Gaseous Diffusion Plant (ORGDP) differed from that of workers at the same plant with no record of occupational exposure to metallic nickel or any nickel compound. A cohort of 814 nickel-exposed workers and one of 1600' controls were identified. The members of both cohorts had a minimum follow-up period of 19 years. Mortality from respiratory cancer and from other causes was examined in both groups. The data showed no evidence of an increased risk of mortality due to respiratory cancer among the nickel-exposed workers. The exposed cohort experienced lower mortality than the controls, both in deaths due to respiratory cancer and in deaths due to all causes, although neither of these differences was statistically significant

  14. A Representation of the Relative Entropy with Respect to a Diffusion Process in Terms of Its Infinitesimal Generator

    Directory of Open Access Journals (Sweden)

    Oliver Faugeras

    2014-12-01

    Full Text Available In this paper we derive an integral (with respect to time representation of the relative entropy (or Kullback–Leibler Divergence R(μ||P, where μ and P are measures on C([0,T];Rd. The underlying measure P is a weak solution to a martingale problem with continuous coefficients. Our representation is in the form of an integral with respect to its infinitesimal generator. This representation is of use in statistical inference (particularly involving medical imaging. Since R(μ||P governs the exponential rate of convergence of the empirical measure (according to Sanov’s theorem, this representation is also of use in the numerical and analytical investigation of finite-size effects in systems of interacting diffusions.

  15. Long-Term Observations of Atmospheric CO2, O3 and BrO over the Transitioning Arctic Ocean Pack-ice: The O-Buoy Chemical Network

    Science.gov (United States)

    Matrai, P.

    2016-02-01

    Autonomous, sea ice-tethered O-Buoys have been deployed (2009-2016) across the Arctic sea ice for long-term atmospheric measurements (http://www.o-buoy.org). O-Buoys (15) provide in-situ concentrations of three sentinel atmospheric chemicals, ozone, CO2 and BrO, as well as meteorological parameters and imagery, over the frozen ocean. O-Buoys were designed to transmit daily data over a period of 2 years while deployed in sea ice, as part of automated ice-drifting stations that include snow/ice measurement systems (e.g. Ice Mass Balance buoys) and oceanographic measurements (e.g. Ice Tethered Profilers). Seasonal changes in Arctic atmospheric chemistry are influenced by changes in the characteristics and presence of the sea ice vs. open water as well as air mass trajectories, especially during the winter-spring and summer-fall transitions when sea ice is melting and freezing, respectively. The O-Buoy Chemical Network provides the unique opportunity to observe these transition periods in real-time with high temporal resolution, and to compare them with those collected on land-based monitoring stations located. Due to the logistical challenges of measurements over the Arctic Ocean region, most long term, in-situ observations of atmospheric chemistry have been made at coastal or island sites around the periphery of the Arctic Ocean, leaving large spatial and temporal gaps that O-Buoys overcome. Advances in floatation, communications, power management, and sensor hardware have been made to overcome the challenges of diminished Arctic sea ice. O-Buoy data provide insights into enhanced seasonal, interannual and spatial variability in atmospheric composition, atmospheric boundary layer control on the amount of halogen activation, enhancement of the atmospheric CO2 signal over the more variable and porous pack ice, and to develop an integrated picture of the coupled ocean/ice/atmosphere system. As part of the Arctic Observing Network, we provide data to the community (www.aoncadis.org).

  16. Development of mathematical techniques for the assimilation of remote sensing data into atmospheric models

    International Nuclear Information System (INIS)

    Seinfeld, J.H.

    1982-01-01

    The problem of the assimilation of remote sensing data into mathematical models of atmospheric pollutant species was investigated. The data assimilation problem is posed in terms of the matching of spatially integrated species burden measurements to the predicted three-dimensional concentration fields from atmospheric diffusion models. General conditions were derived for the reconstructability of atmospheric concentration distributions from data typical of remote sensing applications, and a computational algorithm (filter) for the processing of remote sensing data was developed

  17. Development of mathematical techniques for the assimilation of remote sensing data into atmospheric models

    International Nuclear Information System (INIS)

    Seinfeld, J.H.

    1982-01-01

    The problem of the assimilation of remote sensing data into mathematical models of atmospheric pollutant species was investigated. The problem is posed in terms of the matching of spatially integrated species burden measurements to the predicted three dimensional concentration fields from atmospheric diffusion models. General conditions are derived for the reconstructability of atmospheric concentration distributions from data typical of remote sensing applications, and a computational algorithm (filter) for the processing of remote sensing data is developed

  18. Exact Solution of Fractional Diffusion Model with Source Term used in Study of Concentration of Fission Product in Uranium Dioxide Particle

    International Nuclear Information System (INIS)

    Fang Chao; Cao Jianzhu; Sun Lifeng

    2011-01-01

    The exact solution of fractional diffusion model with a location-independent source term used in the study of the concentration of fission product in spherical uranium dioxide (UO 2 ) particle is built. The adsorption effect of the fission product on the surface of the UO 2 particle and the delayed decay effect are also considered. The solution is given in terms of Mittag-Leffler function with finite Hankel integral transformation and Laplace transformation. At last, the reduced forms of the solution under some special physical conditions, which is used in nuclear engineering, are obtained and corresponding remarks are given to provide significant exact results to the concentration analysis of nuclear fission products in nuclear reactor. (nuclear physics)

  19. SHORT-TERM EXPOSURE TO ATMOSPHERIC AMMONIA DOES NOT AFFECT LOW-TEMPERATURE HARDENING OF WINTER-WHEAT

    NARCIS (Netherlands)

    CLEMENT, JMAM; VENEMA, JH; VANHASSELT, PR

    The effect of atmospheric NH3 on low-temperature hardening of winter wheat (Triticum aestivum L. cv. Urban) was investigated. Growth and photosynthesis were stimulated by ammonia exposure. After a 14 d exposure at moderate temperatures (day/night 18.5/16 degrees C) total nitrogen content was

  20. The rocky road to the upper atmosphere; NASA's quest to create long-term platforms in the stratosphere

    NARCIS (Netherlands)

    Pagitz, M.

    2011-01-01

    A recent program by NASA aims to develop balloons capable of carrying payloads of several tonnes to above 99% of the Earth's atmosphere for up to a hundred days. However, the road to the stratosphere turned out to be much harder and longer than expected

  1. Consequences of Windscale accident (October 1957) and study of the validity of the Sutton's mathematical model of atmospheric diffusion (1960); Etude des consequences de l'accident de Windscale (Octobre 1957) et de la validite du modele mathematique de diffusion atmospherique de Sutton (1960)

    Energy Technology Data Exchange (ETDEWEB)

    Doury, A [Commissariat a l' Energie Atomique (S.C.R.G.R.) Saclay (France).Centre d' Etudes Nucleaires; Martin, J J [Electricite de France (EDF)(S.L.P.R.), 37 - Chinon (France)

    1960-07-01

    The reactor accident that happens at the number 1 pile of Windscale in 1957 was followed by a discharge of radioactive products into the atmosphere from the 1.X.1957 at 4.30 PM to the 12.X.1957 at 3.10 PM. On october the 11{sup th} it was possible to say that there was no more risk either of external irradiation or inhalation. But in adopting a M.A.C. of 0,1 {mu}curie of iodine 131 per litre of milk, the Authority had to control the milk delivery till november 23{sup rd} on a 500 km{sup 2} area. On the other hand, this exceptional accident permit to verify that Sutton's atmospheric diffusion model could give an easy means to foresee, with a sufficient approximation, the consequences of a dispersion of radioactive products into the atmosphere. (author) [French] L'accident survenu a la pile numero 1 de Windscale en 1957 a entraine l'emission de matieres radioactives dans l'atmosphere du 10 octobre a 16h30 au 12 octobre a 15h10. Le 11 octobre, on pouvait dire qu'il n'y avait plus de risque d'irradiation externe ni de danger par inhalation. Mais en adoptant une C.M.A. de 0,1 {mu}curie d'iode 131 par litre de lait, les autorites ont du reglementer la consommation du lait jusqu'au 23 novembre sur une etendue d'environ 500 km{sup 2}. D'autre part, cet accident exceptionnel a permis de verifier que le modele de diffusion atmospherique de Sutton pouvait fournir un moyen commode de prevoir avec une approximation suffisante les consequences d'une dispersion de produits radioactifs dans l'atmosphere. (auteur)

  2. Frontal white matter alterations in short-term medicated panic disorder patients without comorbid conditions: a diffusion tensor imaging study.

    Directory of Open Access Journals (Sweden)

    Borah Kim

    Full Text Available The frontal cortex might play an important role in the fear network, and white matter (WM integrity could be related to the pathophysiology of panic disorder (PD. A few studies have investigated alterations of WM integrity in PD. The aim of this study was to determine frontal WM integrity differences between patients with PD without comorbid conditions and healthy control (HC subjects by using diffusion tensor imaging. Thirty-six patients with PD who had used medication within 1 week and 27 age- and sex-matched HC subjects participated in this study. Structural brain magnetic resonance imaging was performed on all participants. Panic Disorder Severity Scale and Beck Anxiety Inventory (BAI scores were assessed. Tract-based spatial statistics (TBSS was used for image analysis. TBSS analysis showed decreased fractional anisotropy (FA in frontal WM and WM around the frontal lobe, including the corpus callosum of both hemispheres, in patients with PD compared to HC subjects. Moreover, voxel-wise correlation analysis revealed that the BAI scores for patients with PD were positively correlated with their FA values for regions showing group differences in the FA of frontal WM of both hemispheres. Altered integrity in frontal WM of patients with PD without comorbid conditions might represent the structural pathophysiology in these patients, and these changes could be related to clinical symptoms of PD.

  3. Determination of a source term for a time fractional diffusion equation with an integral type over-determining condition

    Directory of Open Access Journals (Sweden)

    Timurkhan S. Aleroev

    2013-12-01

    Full Text Available We consider a linear heat equation involving a fractional derivative in time, with a nonlocal boundary condition. We determine a source term independent of the space variable, and the temperature distribution for a problem with an over-determining condition of integral type. We prove the existence and uniqueness of the solution, and its continuous dependence on the data.

  4. Long-term atmospheric nutrient inputs to the Eastern Mediterranean: sources, solubility and comparison with riverine inputs

    Science.gov (United States)

    Koçak, M.; Kubilay, N.; Tuǧrul, S.; Mihalopoulos, N.

    2010-07-01

    Aerosol and rain samples were collected at a rural site located on the coastline of the Eastern Mediterranean, Erdemli, Turkey between January 1999 and December 2007. Riverine sampling was carried out at five Rivers (Ceyhan, Seyhan, Göksu, Berdan and Lamas) draining into the Northeastern Levantine Basin (NLB) between March 2002 and July 2007. Samples were analyzed for macronutrients of phosphate, silicate, nitrate and ammonium (PO43-, Sidiss, NO3- and NH4+). Phosphate and silicate in aerosol and rainwater showed higher and larger variation during the transitional period (March-May, September) when air flows predominantly originate from North Africa and Middle East/Arabian Peninsula. Deficiency of alkaline material were found to be the main reason of the acidic rain events whilst high pH values (>7) were associated with high Sidiss concentrations due to sporadic dust events. In general, lowest nitrate and ammonium concentrations in aerosol and rainwater were associated with air flow from the Mediterranean Sea. Unlike NO3- and NH4+ (Dissolved Inorganic Nitrogen, DIN), there were statistical differences for PO43- and Sidiss solubilities in sea-water and pure-water. Solubilities of PO43- and Sidiss were found to be related with air mass back trajectories and pH. Comparison of atmospheric with riverine fluxes demonstrated that DIN and PO43- fluxes to NLB were dominated by atmosphere (~90% and ~60% respectively) whereas the input of Si was mainly derived from riverine runoff (~90%). N/P ratios (atmosphere ~233; riverine ~28) revealed that NLB receives excessive amounts of DIN and this unbalanced P and N inputs may provoke even more phosphorus deficiency. Molar Si/N ratios (atmosphere + riverine) suggested Si limitation which might cause a switch from diatom dominated phytoplankton communities to non-siliceous populations in NLB.

  5. On the role of ozone in long-term trends in the upper atmosphere-ionosphere system

    Czech Academy of Sciences Publication Activity Database

    Laštovička, Jan

    2012-01-01

    Roč. 30, č. 5 (2012), s. 811-816 ISSN 0992-7689 R&D Projects: GA ČR GAP209/10/1792 Keywords : Ionosphere-atmosphere interactions * Mid-latitude ionosphere Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 1.518, year: 2012 http://www.ann-geophys.net/30/811/2012/angeo-30-811-2012.html

  6. Comparative assessment of therapeutic response to physiotherapy with or without botulinum toxin injection using diffusion tensor tractography and clinical scores in term diplegic cerebral palsy children.

    Science.gov (United States)

    Chaturvedi, Saurabh K; Rai, Yogita; Chourasia, Ankita; Goel, Puneet; Paliwal, Vimal K; Garg, Ravindra K; Rathore, Ram Kishore S; Pandey, Chandra M; Gupta, Rakesh K

    2013-08-01

    The present study was to compare the effects of combined therapy [botulinum (BTX) plus physiotherapy] with physiotherapy alone using diffusion tensor imaging (DTI) derived fractional anisotropy (FA) values of motor and sensory fiber bundles and clinical grade of the disability to see the value of BTX in term children with spastic diplegic cerebral palsy (CP). Clinically diagnosed 36 children participated in the study. All these children were born at term, and had no history of seizures. The study was randomly categorized into two groups: group I (n=18) - physiotherapy alone and group II (n=18) - physiotherapy plus BTX injection. Quantitative diffusion tensor tractography on all these children was performed on motor and sensory fiber bundles on baseline as well as after 6months of therapy. Motor function and clinical grades were also measured by gross motor function measures (GMFM) scale on both occasions. We observed significant change in FA value in motor and sensory fiber bundle as well as in GMFM scores at 6months compared to baseline study in both the groups. However, delta change and relative delta change in FA values of sensory and motor fiber bundle as well as GMFM score between group I and group II was statistically insignificant. We conclude that addition of BTX to physiotherapy regimen does not influence the outcome at 6months with similar insult in children with term diplegic spastic CP. This information may influence management of diplegic CP especially in developing countries, where BTX is beyond the reach of these children. Copyright © 2012 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.

  7. Evaluation of short-term response of high intensity focused ultrasound ablation for primary hepatic carcinoma: Utility of contrast-enhanced MRI and diffusion-weighted imaging

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Yuanyuan; Zhao Jiannong [Department of Radiology, Second Affiliated Hospital, Chongqing Medical University, No. 74 Linjiang Rd, Yuzhong District, Chongqing 400010 (China); Guo Dajing, E-mail: guodaj@163.com [Department of Radiology, Second Affiliated Hospital, Chongqing Medical University, No. 74 Linjiang Rd, Yuzhong District, Chongqing 400010 (China); Zhong Weijia [Department of Radiology, Second Affiliated Hospital, Chongqing Medical University, No. 74 Linjiang Rd, Yuzhong District, Chongqing 400010 (China); Ran Lifen [Clinical Center for Tumor Therapy, Second Affiliated Hospital, Chongqing Medical University, No. 74 Linjiang Rd, Yuzhong District, Chongqing 400010 (China)

    2011-09-15

    Objective: To explore the significance of contrast-enhanced MRI (CE-MRI) and diffusion-weighted imaging (DWI) in evaluating the short-term response of high intensity focused ultrasound (HIFU) ablation for primary hepatic carcinoma (PHC). Methods: Thirty-nine lesions in the livers of 27 patients were performed HIFU ablation. Conventional MRI sequences, CE-MRI and DWI were performed 1 week before HIFU and 1 week, 3 months after the therapy, respectively. The short-term responses of HIFU for all lesions were evaluated with MRI. Results: 28 of the 39 lesions (28/39, 71.8%) showed complete necrosis with no enhancement 1 week and 3 months after HIFU. The apparent diffusion coefficient (ADC) values 1 week and 3 months after HIFU were significantly higher than those 1 week before treatment (p < 0.05). The tumor recurrence was detected in 7 of the 39 lesions (7/39, 17.9%) which had no significant enhancement 1 week after HIFU. On the 3 months follow-up, focal nodules were found on the inner aspects of the treated areas. The ADC values had no significant difference between 1 week before and after treatment (p > 0.05), however, they were significantly higher 3 months after HIFU (p < 0.05). The tumor residuals were detected in 4 of the 39 lesions (4/39, 10.3%) showing enhancement 1 week after treatment and increased size 3 months after HIFU. The ADC values had no significant difference among 1 week before HIFU, 1 week and 3 months after treatment (p > 0.05). Conclusion: CE-MRI and DWI can be employed to evaluate the short-term response of HIFU ablation for PHC and to guide the patient management.

  8. Modeling long-term carbon residue in the ocean-atmosphere system following large CO2 emissions

    Science.gov (United States)

    Towles, N. J.; Olson, P.; Gnanadesikan, A.

    2013-12-01

    We use the LOSCAR carbon cycle model (Zeebe et al., 2009; Zeebe, 2012) to calculate the residual carbon in the ocean and atmosphere following large CO2 emissions. We consider the system response to CO2 emissions ranging from 100 to 20000 PgC, and emission durations from 100 yr to 100 kyr, subject to a wide range of system parameters such as the strengths of silicate weathering and the oceanic biological carbon pump. We define the carbon gain factor as the ratio of residual carbon in the ocean-atmosphere to the total emitted carbon. For moderate sized emissions shorter than about 50 kyr, we find that the carbon gain factor grows during the emission and peaks at about 1.7, primarily due to the erosion of carbonate marine sediments. In contrast, for longer emissions, the carbon gain factor peaks at a smaller value, and for very large emissions (more than 5000 PgC), the gain factor decreases with emission size due to carbonate sediment exhaustion. This gain factor is sensitive to model parameters such as low latitude efficiency of the biological pump. The timescale for removal of the residual carbon (reducing the carbon gain factor to zero) depends strongly on the assumed sensitivity of silicate weathering to atmospheric pCO2, and ranges from less than one million years to several million years.

  9. Temperature-Dependent Diffusion of H2SO4 in Air at Atmospherically Relevant Conditions: Laboratory Measurements Using Laminar Flow Technique.

    Czech Academy of Sciences Publication Activity Database

    Brus, David; Škrabalová, Lenka; Herrmann, E.; Olenius, T.; Trávníčková, Tereza; Makkonen, U.; Merikanto, J.

    2017-01-01

    Roč. 8, č. 7 (2017), č. článku 132. ISSN 2073-4433 R&D Projects: GA ČR GAP209/11/1342 Grant - others:ERC(FI) 257360; AFCE(FI) 272041; GA AF(FI) 288440 Institutional support: RVO:67985858 Keywords : diffusion coefficient * sulfuric acid * laminar flow tube Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry Impact factor: 1.487, year: 2016

  10. Atmospheric nutrient inputs to the northern levantine basin from a long-term observation: sources and comparison with riverine inputs

    Directory of Open Access Journals (Sweden)

    M. Koçak

    2010-12-01

    Full Text Available Aerosol and rainwater samples have been collected at a rural site located on the coastline of the Eastern Mediterranean, Erdemli, Turkey between January 1999 and December 2007. Riverine sampling was carried out at five Rivers (Ceyhan, Seyhan, Göksu, Berdan and Lamas draining into the Northeastern Levantine Basin (NLB between March 2002 and July 2007. Samples have been analyzed for macronutrients of phosphate, silicate, nitrate and ammonium (PO43−, Sidiss, NO3 and NH4+. Phosphate and silicate in aerosol and rainwater showed higher and larger variations during the transitional period when air flows predominantly originate from North Africa and Middle East/Arabian Peninsula. Deficiency of alkaline material have been found to be the main reason of the acidic rain events whilst high pH values (>7 have been associated with high Sidiss concentrations due to sporadic dust events. In general, lowest nitrate and ammonium concentrations in aerosol and rainwater have been associated with air flow from the Mediterranean Sea. Comparison of atmospheric with riverine fluxes demonstrated that DIN and PO43− fluxes to NLB have been dominated by atmosphere (~90% and ~60% respectively whereas the input of Si was mainly derived from riverine runoff (~90%. N/P ratios in the atmospheric deposition (233; riverine discharge (28 revealed that NLB receives excessive amounts of DIN and this unbalanced P and N inputs may provoke even more phosphorus deficiency. Observed molar Si/N ratio suggested Si limitation relative to nitrogen might cause a switch from diatom dominated communities to non-siliceous populations particularly at coastal NLB.

  11. Atmospheric nutrient inputs to the northern levantine basin from a long-term observation: sources and comparison with riverine inputs

    Science.gov (United States)

    Koçak, M.; Kubilay, N.; Tuğrul, S.; Mihalopoulos, N.

    2010-12-01

    Aerosol and rainwater samples have been collected at a rural site located on the coastline of the Eastern Mediterranean, Erdemli, Turkey between January 1999 and December 2007. Riverine sampling was carried out at five Rivers (Ceyhan, Seyhan, Göksu, Berdan and Lamas) draining into the Northeastern Levantine Basin (NLB) between March 2002 and July 2007. Samples have been analyzed for macronutrients of phosphate, silicate, nitrate and ammonium (PO43-, Sidiss, NO3- and NH4+). Phosphate and silicate in aerosol and rainwater showed higher and larger variations during the transitional period when air flows predominantly originate from North Africa and Middle East/Arabian Peninsula. Deficiency of alkaline material have been found to be the main reason of the acidic rain events whilst high pH values (>7) have been associated with high Sidiss concentrations due to sporadic dust events. In general, lowest nitrate and ammonium concentrations in aerosol and rainwater have been associated with air flow from the Mediterranean Sea. Comparison of atmospheric with riverine fluxes demonstrated that DIN and PO43- fluxes to NLB have been dominated by atmosphere (~90% and ~60% respectively) whereas the input of Si was mainly derived from riverine runoff (~90%). N/P ratios in the atmospheric deposition (233); riverine discharge (28) revealed that NLB receives excessive amounts of DIN and this unbalanced P and N inputs may provoke even more phosphorus deficiency. Observed molar Si/N ratio suggested Si limitation relative to nitrogen might cause a switch from diatom dominated communities to non-siliceous populations particularly at coastal NLB.

  12. Atmosphere, water, sun, carbon dioxide, weather, climate, living - some fundamental terms; Atmosphaere, Wasser, Sonne, Kohlenstoffdioxid, Wetter, Klima, Leben - einige Grundbegriffe

    Energy Technology Data Exchange (ETDEWEB)

    Hopp, Vollrath

    2012-07-01

    The author of the book under consideration explains the physical, chemical and meteorological principles. The knowledge of these fundamentals is necessary in order to understand the weather in its manifold manifestations. Solar energy, atmosphere, oceans and continents are interrelated. Large amounts of energy are exchanged at their interfaces causing high temperature differences and strong materials flows. A historical review shows that the climatic change is determined by changes in solar activity, cosmic radiation, inclination of the earth's axis (from about 24.5 to 22.5 ) in periods of up to 41,000 years, the Earth's magnetic field, the gravitation and by large volcanic eruptions.

  13. Diffuse large B-cell lymphoma associated with the use of biologic and other investigational agents: the importance of long-term post-marketing safety surveillance.

    Science.gov (United States)

    Goddard, Allison; Borovicka, Judy H; West, Dennis P; Evens, Andrew M; Laumann, Anne

    2011-01-01

    This case report describes a patient who developed diffuse large B-cell lymphoma (DLBCL) after receiving courses of two investigational biologic agents and cyclosporine followed by more than four years of subcutaneous efalizumab for the treatment of extensive chronic plaque psoriasis. Three years later, the patient remains free of lymphoma and his psoriasis is well controlled with thrice-weekly narrow-band ultraviolet phototherapy. This case emphasizes the importance of continued long-term post-marketing safety surveillance and the early reporting of all possible serious side effects, including cancers, related to the use of any newly available product. In particular, surveillance should focus on the immunomodulating biologic agents in order to identify possible dangerous sequelae.

  14. On the role of atmosphere-ocean interactions in the expected long-term changes of the Earth's ozone layer caused by greenhouse gases

    Science.gov (United States)

    Zadorozhny, Alexander; Dyominov, Igor

    It is well known that anthropogenic emissions of greenhouse gases into the atmosphere produce a global warming of the troposphere and a global cooling of the stratosphere. The expected stratospheric cooling essentially influences the ozone layer via increased polar stratospheric cloud formation and via temperature dependences of the gas phase reaction rates. One more mechanism of how greenhouse gases influences the ozone layer is enhanced water evaporation from the oceans into the atmosphere because of increasing temperatures of the ocean surface due to greenhouse effect. The subject of this paper is a study of the influence of anthropogenic pollution of the atmosphere by the greenhouse gases CO2, CH4, N2O and ozone-depleting chlorine and bromine compounds on the expected long-term changes of the ozone layer with taking into account an increase of water vapour content in the atmosphere due to greenhouse effect. The study based on 2-D zonally averaged interactive dynamical radiative-photochemical model of the troposphere and stratosphere. The model allows to self-consistently calculating 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 two types. It was supposed in the model that an increase of the ocean surface temperature caused by greenhouse effect is similar to calculated increase of atmospheric surface temperature. Evaporation rate from the ocean surface was computed in dependence of latitude. The model time-dependent runs were made for the period from 1975 to 2100 using two IPCC scenarios depicting maximum and average expected increases of greenhouse gases in the atmosphere. The model calculations show that anthropogenic increasing of water vapour abundance in the atmosphere due to heating of the ocean surface caused by greenhouse effect gives a sensible contribution to the expected ozone

  15. Relationship between diffusion tensor fractional anisotropy and long-term motor outcome in patients with hemiparesis after middle cerebral artery infarction.

    Science.gov (United States)

    Koyama, Tetsuo; Marumoto, Kohei; Miyake, Hiroji; Domen, Kazuhisa

    2014-10-01

    Magnetic resonance diffusion tensor fractional anisotropy (DTI-FA) is often used to characterize neural damage after stroke. Here we assessed the relationship between DTI-FA and long-term motor outcome in patients after middle cerebral artery (MCA) infarction. Fractional anisotropy (FA) maps were generated from diffusion tensor brain images obtained from 16 patients 14-18 days postinfarction, and tract-based spatial statistics (TBSS) analysis was applied. Regions of interest were set within the right and left corticospinal tracts, and mean FA values were extracted from individual TBSS data. Hemiparesis motor outcome was evaluated according to Brunnstrom stage (BRS: 1-6, severe-normal) for separate shoulder/elbow/forearm, hand, and lower extremity functions, as well as the motor component score of the Functional Independence Measure (FIM-motor: 13-91, null-full) 5-7 months after onset. Ratios between FA values in the affected and unaffected hemispheres (rFA) were assessed by BRS and FIM-motor scores. rFA values were .636-.984 (median, .883) and BRS scores were 1-6 (median, 3) for shoulder/elbow/forearm, 2-6 (median, 3) for hand, and 3-6 (median, 5) for the lower extremities. FIM-motor scores were 51-90 (median, 75). Analysis revealed significant relationships between rFA and BRS data (correlation coefficient: .687 for shoulder/elbow/forearm, .579 for hand, and .623 for lower extremities) but no significance relationship between rFA and FIM-motor scores. The results suggest that DTI-FA is applicable for predicting the long-term outcome of extremity functions after MCA infarction. Copyright © 2014 National Stroke Association. Published by Elsevier Inc. All rights reserved.

  16. Atmospheric Direct Uptake and Long-term Fate of Radiocesium in Trees after the Fukushima Nuclear Accident

    Science.gov (United States)

    Mahara, Yasunori; Ohta, Tomoko; Ogawa, Hideki; Kumata, Atsushi

    2014-11-01

    Large areas of forests were radioactively contaminated by the Fukushima nuclear accident of 2011, and forest decontamination is now an important problem in Japan. However, whether trees absorb radioactive fallout from soil via the roots or directly from the atmosphere through the bark and leaves is unclear. We measured the uptake of radiocesium by trees in forests heavily contaminated by the Fukushima nuclear accident. The radiocesium concentrations in sapwood of two tree species, the deciduous broadleaved konara (Quercus serrata) and the evergreen coniferous sugi (Cryptomeria japonica), were higher than that in heartwood. The concentration profiles showed anomalous directionality in konara and non-directionality in sugi, indicating that most radiocesium in the tree rings was directly absorbed from the atmosphere via bark and leaves rather than via roots. Numerical modelling shows that the maximum 137Cs concentration in the xylem of konara will be achieved 28 years after the accident. Conversely, the values for sugi will monotonously decrease because of the small transfer factor in this species. Overall, xylem 137Cs concentrations will not be affected by root uptake if active root systems occur 10 cm below the soil.

  17. Quantum diffusion

    International Nuclear Information System (INIS)

    Habib, S.

    1994-01-01

    We consider a simple quantum system subjected to a classical random force. Under certain conditions it is shown that the noise-averaged Wigner function of the system follows an integro-differential stochastic Liouville equation. In the simple case of polynomial noise-couplings this equation reduces to a generalized Fokker-Planck form. With nonlinear noise injection new ''quantum diffusion'' terms rise that have no counterpart in the classical case. Two special examples that are not of a Fokker-Planck form are discussed: the first with a localized noise source and the other with a spatially modulated noise source

  18. Detailed source term estimation of the atmospheric release for the Fukushima Daiichi Nuclear Power Station accident by coupling simulations of atmospheric dispersion model with improved deposition scheme and oceanic dispersion model

    Science.gov (United States)

    Katata, G.; Chino, M.; Kobayashi, T.; Terada, H.; Ota, M.; Nagai, H.; Kajino, M.; Draxler, R.; Hort, M. C.; Malo, A.; Torii, T.; Sanada, Y.

    2014-06-01

    Temporal variations in the amount of radionuclides released into the atmosphere during the Fukushima Dai-ichi Nuclear Power Station (FNPS1) accident and their atmospheric and marine dispersion are essential to evaluate the environmental impacts and resultant radiological doses to the public. In this paper, we estimate a detailed time trend of atmospheric releases during the accident by combining environmental monitoring data with atmospheric model simulations from WSPEEDI-II (Worldwide version of System for Prediction of Environmental Emergency Dose Information), and simulations from the oceanic dispersion model SEA-GEARN-FDM, both developed by the authors. A sophisticated deposition scheme, which deals with dry and fogwater depositions, cloud condensation nuclei (CCN) activation and subsequent wet scavenging due to mixed-phase cloud microphysics (in-cloud scavenging) for radioactive iodine gas (I2 and CH3I) and other particles (CsI, Cs, and Te), was incorporated into WSPEEDI-II to improve the surface deposition calculations. The fallout to the ocean surface calculated by WSPEEDI-II was used as input data for the SEA-GEARN-FDM calculations. Reverse and inverse source-term estimation methods based on coupling the simulations from both models was adopted using air dose rates and concentrations, and sea surface concentrations. The results revealed that the major releases of radionuclides due to FNPS1 accident occurred in the following periods during March 2011: the afternoon of 12 March due to the wet venting and hydrogen explosion at Unit 1, the morning of 13 March after the venting event at Unit 3, midnight of 14 March when the SRV (Safely Relief Valve) at Unit 2 was opened three times, the morning and night of 15 March, and the morning of 16 March. According to the simulation results, the highest radioactive contamination areas around FNPS1 were created from 15 to 16 March by complicated interactions among rainfall, plume movements, and the temporal variation of

  19. Long-Term Atmospheric Corrosion Behavior of Epoxy Prime Coated Aluminum Alloy 7075-T6 in Coastal Environment

    Directory of Open Access Journals (Sweden)

    Sheng Zhang

    2018-06-01

    Full Text Available The atmospheric corrosion of epoxy prime coated aluminum alloy 7075-T6 exposed for 7, 12 and 20 years was investigated. The remaining thicknesses of epoxy prime coatings for macroscopically intact coating areas followed a normal distribution and decreased linearly. EIS results demonstrated that the corrosion resistance of the coating decreased with exposure time. After 20 years of exposure, the epoxy coating had lost its protection as cracks existed within the coating and exfoliation corrosion had occurred on the substrate. The substrate was sensitive to exfoliation corrosion through metallographic and TEM analysis. The corrosion products were mainly hydroxides of aluminum. The morphology and chemical compositions of the coating bubbling area and propagation characterizations of exfoliation corrosion were analyzed by SEM, EPMA and EDS. Cracks between the lumps of corrosion products provided the channels for the transmission of corrosion mediums. Furthermore, the mechanical model was proposed to analyze the propagation characterization of exfoliation corrosion.

  20. New Insights in the Long-Term Atmospheric Corrosion Mechanisms of Low Alloy Steel Reinforcements of Cultural Heritage Buildings

    Directory of Open Access Journals (Sweden)

    Marie Bouchar

    2017-06-01

    Full Text Available Reinforcing clamps made of low alloy steel from the Metz cathedral and corroded outdoors during 500 years were studied by OM, FESEM/EDS, and micro-Raman spectroscopy. The corrosion product layer is constituted of a dual structure. The outer layer is mainly constituted of goethite and lepidocrocite embedding exogenous elements such as Ca and P. The inner layer is mainly constituted of ferrihydrite. The behaviour of the inner layer under conditions simulating the wetting stage of the RH wet/dry atmospheric corrosion cycle was observed by in situ micro-Raman spectroscopy. The disappearance of ferrihydrite near the metal/oxide interface strongly suggests a mechanism of reductive dissolution caused by the oxidation of the metallic substrate and was observed for the first time in situ on an archaeological system.

  1. Estimation of the time-dependent radioactive source-term from the Fukushima nuclear power plant accident using atmospheric transport modelling

    Science.gov (United States)

    Schoeppner, M.; Plastino, W.; Budano, A.; De Vincenzi, M.; Ruggieri, F.

    2012-04-01

    Several nuclear reactors at the Fukushima Dai-ichi power plant have been severely damaged from the Tōhoku earthquake and the subsequent tsunami in March 2011. Due to the extremely difficult on-site situation it has been not been possible to directly determine the emissions of radioactive material. However, during the following days and weeks radionuclides of 137-Caesium and 131-Iodine (amongst others) were detected at monitoring stations throughout the world. Atmospheric transport models are able to simulate the worldwide dispersion of particles accordant to location, time and meteorological conditions following the release. The Lagrangian atmospheric transport model Flexpart is used by many authorities and has been proven to make valid predictions in this regard. The Flexpart software has first has been ported to a local cluster computer at the Grid Lab of INFN and Department of Physics of University of Roma Tre (Rome, Italy) and subsequently also to the European Mediterranean Grid (EUMEDGRID). Due to this computing power being available it has been possible to simulate the transport of particles originating from the Fukushima Dai-ichi plant site. Using the time series of the sampled concentration data and the assumption that the Fukushima accident was the only source of these radionuclides, it has been possible to estimate the time-dependent source-term for fourteen days following the accident using the atmospheric transport model. A reasonable agreement has been obtained between the modelling results and the estimated radionuclide release rates from the Fukushima accident.

  2. Long-term observation of water-soluble chemical components in the bulk atmospheric aerosols collected at Okinawa, Japan

    Science.gov (United States)

    Handa, Daishi; Somada, Yuka; Ijyu, Moriaki; Azechi, Sotaro; Nakaema, Fumiya; Arakaki, Takemitsu; Tanahara, Akira

    2010-05-01

    The economic development and population growth in recent Asia spread air pollution. Emission rate of air pollutants from Asia, in particular oxides of nitrogen, surpassed those from North America and Europe and should continue to exceed them for decades. The study of the long-range transported air pollution from Asian continent has gained a special attention in Japan because of increase in photochemical oxidants in relatively remote islands. Okinawa Island is situated approximately 1500 km south of Tokyo, Japan, 2000 km southeast of Beijing, China, and 1000 km south of South Korea. Its location in Asia is well suited for studying long-range transport of air pollutants in East Asia because maritime air mass prevails during summer, while continental air mass dominates during fall, winter, and spring. The maritime air mass data can be seen as background and can be compared with continental air masses which have been affected by anthropogenic activities. Bulk aerosol samples were collected on quartz filters by using a high volume air sampler. Sampling duration was one week for each sample. We determined the concentrations of water-soluble anions, cations and dissolved organic carbon (DOC) in the bulk aerosols collected at the Cape Hedo Atmosphere and Aerosol Monitoring Station (CHAAMS) using ion chromatography, atomic absorption spectrometry, and total organic carbon analyzer, respectively. We will report water-soluble chemical components data of anions, cations and DOC in bulk atmospheric aerosols collected at CHAAMS during August, 2005 to April, 2010. Seasonal variation of water-soluble chemical components showed that the concentrations were relatively low in summer, higher in fall and winter, and the highest in spring. When air mass came from Asian Continent, the concentrations of water-soluble chemical components were much higher compared to the other directions. In addition, we calculated background concentration of water-soluble chemical components at Okinawa

  3. Atmospheric discharge and dispersion of radionuclides during the Fukushima Dai-ichi Nuclear Power Plant accident. Part I: Source term estimation and local-scale atmospheric dispersion in early phase of the accident

    International Nuclear Information System (INIS)

    Katata, Genki; Ota, Masakazu; Terada, Hiroaki; Chino, Masamichi; Nagai, Haruyasu

    2012-01-01

    The atmospheric release of 131 I and 137 Cs in the early phase of the Fukushima Dai-ichi Nuclear Power Plant (FNPP1) accident from March 12 to 14, 2011 was estimated by combining environmental data with atmospheric dispersion simulations under the assumption of a unit release rate (1 Bq h −1 ). For the simulation, WSPEEDI-II computer-based nuclear emergency response system was used. Major releases of 131 I (>10 15 Bq h −1 ) were estimated when air dose rates increased in FNPP1 during the afternoon on March 12 after the hydrogen explosion of Unit 1 and late at night on March 14. The high-concentration plumes discharged during these periods flowed to the northwest and south–southwest directions of FNPP1, respectively. These plumes caused a large amount of dry deposition on the ground surface along their routes. Overall, the spatial pattern of 137 Cs and the increases in the air dose rates observed at the monitoring posts around FNPP1 were reproduced by WSPEEDI-II using estimated release rates. The simulation indicated that air dose rates significantly increased in the south–southwest region of FNPP1 by dry deposition of the high-concentration plume discharged from the night of March 14 to the morning of March 15. - Highlights: ► Source term during the Fukushima Dai-ichi Nuclear Power Plant accident was estimated. ► Atmospheric dispersion simulation was carried out for estimation. ► Major releases were estimated in the afternoon on March 12 and the night on March 14. ► Air dose rate increased due to dry deposition during the night of March 14.

  4. Atomic diffusion in stars

    CERN Document Server

    Michaud, Georges; Richer, Jacques

    2015-01-01

    This book gives an overview of atomic diffusion, a fundamental physical process, as applied to all types of stars, from the main sequence to neutron stars. The superficial abundances of stars as well as their evolution can be significantly affected. The authors show where atomic diffusion plays an essential role and how it can be implemented in modelling.  In Part I, the authors describe the tools that are required to include atomic diffusion in models of stellar interiors and atmospheres. An important role is played by the gradient of partial radiative pressure, or radiative acceleration, which is usually neglected in stellar evolution. In Part II, the authors systematically review the contribution of atomic diffusion to each evolutionary step. The dominant effects of atomic diffusion are accompanied by more subtle effects on a large number of structural properties throughout evolution. One of the goals of this book is to provide the means for the astrophysicist or graduate student to evaluate the importanc...

  5. Atmospheric tritium. Measurement and application

    International Nuclear Information System (INIS)

    Frejaville, Gerard

    1967-02-01

    The possible origins of atmospheric tritium are reviewed and discussed. A description is given of enrichment (electrolysis and thermal diffusion) and counting (gas counters and liquid scintillation counters) processes which can be used for determining atmospheric tritium concentrations. A series of examples illustrates the use of atmospheric tritium for resolving a certain number of hydrological and glaciological problems. (author) [fr

  6. Measurement of the diffuse atmospheric and cosmic γ-radiation in the energy range 1-10 MeV by a balloon carried Compton-telescope

    International Nuclear Information System (INIS)

    Lichti, G.

    1975-01-01

    The operation and design of a low-energy γ-compton telescope, developed and constructed at the Max-Planck-Institut fuer extraterrestrische Physik, are reported on. For energies of about 1 MeV, the telescope has an energy resolution of 30% (FWHM) and an angular resolution of +- 20 0 . In spite of the low efficiency of only about 0.5%, the vertical γ-flux could be measured for the first time in two balloon flights, and the extragalactic origin of the diffuse component of the cosmic γ-radiation could be demonstrated. The energy spectrum of this radiation was measured. The result is compared with measurements of other experiments, and theoretical models to describe the origin of this radiation are discussed. (orig.) [de

  7. The application of an eddy diffusivity model to the dispersion of radionuclides in the atmosphere and the calculation of cloud gamma exposure

    International Nuclear Information System (INIS)

    Maul, P.R.

    1981-05-01

    A model which has been applied successfully to the study of the mesoscale transport of sulphur compounds can be adapted for radionuclides released from nuclear power stations. Although more complicated than the conventional Gaussian plume models it has several important advantages including the better representation of dry deposition and the variation of dispersion parameters with height above the surface. Building entrainment can be included in a straightforward manner and an approximate method can be used to incorporate isotope-dependent deposition velocities. A new method of calculating cloud gamma exposure is described which is particularly suited to eddy diffusivity models. This model will be used as an alternative to Gaussian plume methods in the BNL safety code NECTAR. (author)

  8. Voxel-based morphometry and diffusion-tensor MR imaging of the brain in long-term survivors of childhood leukemia.

    Science.gov (United States)

    Porto, L; Preibisch, C; Hattingen, E; Bartels, M; Lehrnbecher, T; Dewitz, R; Zanella, F; Good, C; Lanfermann, H; DuMesnil, R; Kieslich, M

    2008-11-01

    The aims of this study were to detect morphological changes in neuroanatomical components in adult survivors of acute lymphoblastic leukemia (ALL). Voxel-based morphometry (VBM) can be used to detect subtle structural changes in brain morphology and via analysis of fractional anisotropy (FA), diffusion-tensor imaging (DTI) can non-invasively probe white matter (WM) integrity. We used VBM and DTI to examine 20 long-term survivors of ALL and 21 healthy matched controls. Ten ALL survivors received chemotherapy and irradiation; ten survivors received chemotherapy alone during childhood. Imaging was performed on a 3.0-T MRI. For VBM, group comparisons of segmented T1-weighted grey matter (GM) and WM images from controls and ALL survivors were performed separately for patients who received chemotherapy alone and who received chemotherapy and irradiation. For DTI, FA in WM was compared for the same groups. Survivors of childhood ALL who underwent cranial irradiation during childhood had smaller WM volumes and reduced GM concentration within the caudate nucleus and thalamus. The FA in WM was reduced in adult survivors of ALL but the effect was more severe after combined treatment with irradiation and chemotherapy. Our results indicate that DTI and VBM can reveal persistent long-term WM and caudate changes in children after ALL treatment, even without T2 changes in conventional imaging.

  9. Atmospheric stabilization of CO2 emissions: Near-term reductions and absolute versus intensity-based targets

    International Nuclear Information System (INIS)

    Timilsina, Govinda R.

    2008-01-01

    This study analyzes CO 2 emissions reduction targets for various countries and geopolitical regions by the year 2030 to stabilize atmospheric concentrations of CO 2 at 450 ppm (550 ppm including non-CO 2 greenhouse gases) level. It also determines CO 2 intensity cuts that would be required in those countries and regions if the emission reductions were to be achieved through intensity-based targets without curtailing their expected economic growth. Considering that the stabilization of CO 2 concentrations at 450 ppm requires the global trend of CO 2 emissions to be reversed before 2030, this study develops two scenarios: reversing the global CO 2 trend in (i) 2020 and (ii) 2025. The study shows that global CO 2 emissions would be limited at 42 percent above 1990 level in 2030 if the increasing trend of global CO 2 emissions were to be reversed by 2020. If reversing the trend is delayed by 5 years, global CO 2 emissions in 2030 would be 52 percent higher than the 1990 level. The study also finds that to achieve these targets while maintaining expected economic growth, the global average CO 2 intensity would require a 68 percent drop from the 1990 level or a 60 percent drop from the 2004 level by 2030

  10. Metabolic shifts in the myocardium in the long-term effect of atmospheric pollution on the body

    Energy Technology Data Exchange (ETDEWEB)

    Tsapok, P I; Turdakin, P G; Barkov, L V; Ovcharuk, I N; Protod' iakonova, T N

    1981-04-01

    Metabolic shifts in the myocardium under conditions of long-term exposure of the body to air pollution were studied in experiments on albino rats. Study of the content of protein, RNA, DNA, glycogen, ATP, lactic and pyruvic acids and the activity of lactate dehydrogenase and creatine kinase in the heart muscle allowed the conclusion that the glycolytic processes are intensified, the bioenergic processes are inhibited and the synthesis of protein and RNA are increased in the myocardium of the experimental animals.

  11. Reversal of Long-Term Trends in Ethane Identified from the Global Atmosphere Watch Reactive Gases Measurement Network

    OpenAIRE

    Helmig, Detlev; Buchmann, Brigitte; Carpenter, Lucy; Claude, Anja; Emmons, Louisa; Flocke, Frank; Franco, Bruno; Galbally, Ian; Hannigan, James; Hueber, Jacques; Koide, Hiroshi; Lewis, Alastair; Masarie, Ken; Mahieu, Emmanuel; Montzka, Stephen

    2016-01-01

    Reactive gases play an important role in climate and air pollution issues. They control the self-cleansing capability of the troposphere, contribute to air pollution and acid deposition, regulate the lifetimes and provide tracers for deciphering sources and sinks for greenhouse gases. Within GAW, the focus is placed on long-term, high-quality observations of ozone (O3), carbon monoxide (CO), volatile organic compounds (VOC), nitrogen oxides (NOx), and sulfur dioxide (SO2). More than 100 stati...

  12. Serial Diffusion Tensor Imaging In Vivo Predicts Long-Term Functional Recovery and Histopathology in Rats following Different Severities of Spinal Cord Injury

    Science.gov (United States)

    Patel, Samir P.; Smith, Taylor D.; VanRooyen, Jenna L.; Powell, David; Cox, David H.; Sullivan, Patrick G.

    2016-01-01

    Abstract The current study demonstrates the feasibility of using serial magnetic resonance imaging (MRI) and diffusion tensor imaging (DTI) in vivo to quantify temporally spinal cord injury (SCI) pathology in adult female Sprague-Dawley rats that were scanned prior to a moderate or severe upper lumbar contusion SCI. Injured rats were behaviorally tested for hind limb locomotion (Basso, Beattie, Bresnahan [BBB] scores) weekly for 4 weeks and scanned immediately after each session, ending with terminal gait analyses prior to euthanasia. As a measure of tissue integrity, fractional anisotropy (FA) values were significantly lower throughout the spinal cord in both injury cohorts at all time-points examined versus pre-injury. Moreover, FA values were significantly lower following severe versus moderate SCI at all time-points, and FA values at the injury epicenters at all time-points were significantly correlated with both spared white and gray matter volumes, as well as lesion volumes. Critically, quantified FA values at subacute (24 h) and all subsequent time-points were highly predictive of terminal behavior, reflected in significant correlations with both weekly BBB scores and terminal gait parameters. Critically, the finding that clinically relevant subacute (24 h) FA values accurately predict long-term functional recovery may obviate long-term studies to assess the efficacy of therapeutics tested experimentally or clinically. In summary, this study demonstrates a reproducible serial MRI procedure to predict the long-term impact of contusion SCI on both behavior and histopathology using subacute DTI metrics obtained in vivo to accurately predict multiple terminal outcome measures, which can be particularly valuable when comparing experimental interventions. PMID:26650623

  13. Long-Term, High-Resolution Survey of Atmospheric Aerosols over Egypt with NASA’s MODIS Data

    Directory of Open Access Journals (Sweden)

    Mohammed Shokr

    2017-10-01

    Full Text Available A decadal survey of atmospheric aerosols over Egypt and selected cities and regions is presented using daily aerosol optical depth (AOD data from NASA’s Moderate Resolution Imaging Spectroradiometer (MODIS at 550 nm wavelength onboard the Aqua satellite. We explore the AOD spatio-temporal variations over Egypt during a 12-year record (2003 to 2014 using the MODIS high-resolution (10 km Level 2 data product. Five cities and two geographic regions that feature different landscape and human activities were selected for detailed analysis. For most of the examined areas, AOD is found to be most frequent in the 0.2–0.3 range, and the highest mean AOD was found to be over Cairo, Alexandria, and the Nile Delta region. Severe events are identified based on AOD higher than a selected threshold. Most of these events are engendered by sand and dust storms that originate from the Western Desert during January–April. Spatial analysis indicates that they cover the Nile Delta region, including cities of Cairo and Alexandria, on the same day. Examination of the spatial gradient of AOD along the four cardinal directions originating from the city’s center reveals seasonally dependent gradients in some cases. The gradients have been linked to locations of industrial activity. No trend of AOD has been observed in the studied areas during the study period, though data from Cairo and Asyut reveal a slight linear increase of AOD. Considering Cairo is commonly perceived as a city of poor air quality, the results show that local events are fairly constrained. The study highlights spatial and seasonal distributions of AOD and links them to geographic and climatic conditions across the country.

  14. Modeling the atmospheric chemistry of TICs

    Science.gov (United States)

    Henley, Michael V.; Burns, Douglas S.; Chynwat, Veeradej; Moore, William; Plitz, Angela; Rottmann, Shawn; Hearn, John

    2009-05-01

    An atmospheric chemistry model that describes the behavior and disposition of environmentally hazardous compounds discharged into the atmosphere was coupled with the transport and diffusion model, SCIPUFF. The atmospheric chemistry model was developed by reducing a detailed atmospheric chemistry mechanism to a simple empirical effective degradation rate term (keff) that is a function of important meteorological parameters such as solar flux, temperature, and cloud cover. Empirically derived keff functions that describe the degradation of target toxic industrial chemicals (TICs) were derived by statistically analyzing data generated from the detailed chemistry mechanism run over a wide range of (typical) atmospheric conditions. To assess and identify areas to improve the developed atmospheric chemistry model, sensitivity and uncertainty analyses were performed to (1) quantify the sensitivity of the model output (TIC concentrations) with respect to changes in the input parameters and (2) improve, where necessary, the quality of the input data based on sensitivity results. The model predictions were evaluated against experimental data. Chamber data were used to remove the complexities of dispersion in the atmosphere.

  15. Long-term monitoring of atmospheric PCDD/Fs at Mount Lulin during spring season: PCDD/F source apportionment through a simultaneous measurement in Southeast Asia.

    Science.gov (United States)

    Hung, Ngo Tuan; Li, Chueh Ting; Wang, Sheng Hsiang; Ou-Yang, Chang-Feng; Lin, Chuan-Yao; Lee, Chung-Te; Lin, Neng-Huei; Chi, Kai Hsien

    2017-10-01

    A long term assessment of atmospheric polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) at Mt. Lulin, located in center of Taiwan was carried out from 2008 to 2013 (n = 81) assuming Mt. Lulin to be background area. During monitoring processes, PCDD/F samples collected in the field occasionally reached high concentration. To investigate this situation, simultaneous sample collection was carried out in Southeast Asia countries (i.e., Vietnam and Thailand) and Taiwan in 2013. The average concentration of atmospheric PCDD/Fs in biomass-burning source regions, namely Son La and Doi Ang Khang were 19.8 ± 12.1 fg I-TEQ m -3 (n = 19) and 17.8 ± 12.4 fg I-TEQ m -3 (n = 20), respectively. In the downwind area of Mt. Lulin, the average concentration of PCDD/Fs was found to be 4.64 ± 3.77 fg I-TEQ m -3 (n = 18). PCDD/F concentration in the source region was much higher than that in the downwind region. On March 19, 2013, the atmospheric PCDD/F concentrations increased dramatically from 7.71 to 484 fg I-TEQ m -3 at Mt. Lulin, which many times exceeded that of assumed source region in Southeast Asia. Moreover, mainland Southeast Asia and the southeast coast of China was suspected to be the main contributors of atmospheric PCDD/Fs and biomass markers, such as nonsea-salt K + and NH 4 + , during the spring. WRF-Chem and Potential Source Contribution Function (PSCF) simulations have confirmed this correlation. It can be concluded that atmospheric PCDD/Fs observed at Mt. Lulin during spring mostly derived from the air mass transport not only from Southeast Asia but also the southeast coast of China. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Long-term climate: interpretation of the Vostok Antarctica drilling data, development of a zonally averaged dynamic model of the atmosphere

    International Nuclear Information System (INIS)

    Genthon, Christophe

    1988-01-01

    climatic state of the atmosphere through baro-clinic instability linear theory. This model is intended for investigating and simulating the climate of the glacial to interglacial transitions. It makes a fair balance between the qualities of a general circulation model and the Computing speed performances necessary for long term simulations. (author) [fr

  17. Decadal-scale variability of diffuse CO2 emissions and seismicity revealed from long-term monitoring (1995–2013) at Mammoth Mountain, California, USA

    Science.gov (United States)

    Werner, Cynthia A.; Bergfeld, Deborah; Farrar, Chris; Doukas, Michael P.; Kelly, Peter; Kern, Christoph

    2014-01-01

    Mammoth Mountain, California, is a dacitic volcano that has experienced several periods of unrest since 1989. The onset of diffuse soil CO2 emissions at numerous locations on the flanks of the volcano began in 1989–1990 following an 11-month period of heightened seismicity. CO2 emission rates were measured yearly from 1995 to 2013 at Horseshoe Lake (HSL), the largest tree kill area on Mammoth Mountain, and measured intermittently at four smaller degassing areas around Mammoth from 2006 to 2013. The long-term record at HSL shows decadal-scale variations in CO2 emissions with two peaks in 2000–2001 and 2011–2012, both of which follow peaks in seismicity by 2–3 years. Between 2000 and 2004 emissions gradually declined during a seismically quiet period, and from 2004 to 2009 were steady at ~ 100 metric tonnes per day (t d− 1). CO2emissions at the four smaller tree-kill areas also increased by factors of 2–3 between 2006 and 2011–2012, demonstrating a mountain-wide increase in degassing. Delays between the peaks in seismicity and degassing have been observed at other volcanic and hydrothermal areas worldwide, and are thought to result from an injection of deep CO2-rich fluid into shallow subsurface reservoirs causing a pressurization event with a delayed transport to the surface. Such processes are consistent with previous studies at Mammoth, and here we highlight (1) the mountain-wide response, (2) the characteristic delay of 2–3 years, and (3) the roughly decadal reoccurrence interval for such behavior. Our best estimate of total CO2 degassing from Mammoth Mountain was 416 t d− 1 in 2011 during the peak of emissions, over half of which was emitted from HSL. The cumulative release of CO2 between 1995 and 2013 from diffuse emissions is estimated to be ~ 2–3 Mt, and extrapolation back to 1989 gives ~ 4.8 Mt. This amount of CO2 release is similar to that produced by the mid-sized (VEI 3) 2009 eruption of Redoubt Volcano in Alaska (~ 2.3

  18. Accurate gamma and MeV-electron track reconstruction with an ultra-low diffusion Xenon/TMA TPC at 10 atmospheres

    CERN Document Server

    González-Díaz, Diego; Borges, F.I.G.; Camargo, M.; Cárcel, S.; Cebrián, S.; Cervera, A.; Conde, C.A.N.; Dafni, T.; Díaz, J.; Esteve, R.; Fernandes, L.M.P.; Ferrario, P.; Ferreira, A.L.; Freitas, E.D.C.; Gehman, V.M.; Goldschmidt, A.; Gómez-Cadenas, J.J.; Gutiérrez, R.M.; Hauptman, J.; Hernando Morata, J.A.; Herrera, D.C.; Irastorza, I.G.; Labarga, L.; Laing, A.; Liubarsky, I.; Lopez-March, N.; Lorca, D.; Losada, M.; Luzón, G.; Marí, A.; Martín-Albo, J.; Martínez-Lema, G.; Martínez, A.; Miller, T.; Monrabal, F.; Monserrate, M.; Monteiro, C.M.B.; Mora, F.J.; Moutinho, L.M.; Muñoz Vidal, J.; Nebot-Guinot, M.; Nygren, D.; Oliveira, C.A.B.; Pérez, J.; Pérez Aparicio, J.L.; Querol, M.; Renner, J.; Ripoll, L.; Rodríguez, J.; Santos, F.P.; dos Santos, J.M.F.; Serra, L.; Shuman, D.; Simón, A.; Sofka, C.; Sorel, M.; Toledo, J.F.; Torrent, J.; Tsamalaidze, Z.; Veloso, J.F.C.A.; Villar, J.A.; Webb, R.; White, J.T.; Yahlali, N.; Azevedo, C.; Aznar, F.; Calvet, D.; Castel, J.; Ferrer-Ribas, E.; García, J.A.; Giomataris, I.; Gómez, H.; Iguaz, F.J.; Lagraba, A.; Le Coguie, A.; Mols, J.P.; Şahin, Ö.; Rodríguez, A.; Ruiz-Choliz, E.; Segui, L.; Tomás, A.; Veenhof, R.

    2015-01-01

    We report the performance of a 10 atm Xenon/trimethylamine time projection chamber (TPC) for the detection of X-rays (30 keV) and gamma-rays (0.511-1.275 MeV) in conjunction with the accurate tracking of the associated electrons. When operated at such a high pressure and in 1%-admixtures, trimethylamine (TMA) endows Xenon with an extremely low electron diffusion (1.3 +-0.13 mm-sigma (longitudinal), 0.8 +-0.15 mm-sigma (transverse) along 1 m drift) besides forming a convenient Penning-Fluorescent mixture. The TPC, that houses 1.1 kg of gas in its active volume, operated continuously for 100 live-days in charge amplification mode. The readout was performed through the recently introduced microbulk Micromegas technology and the AFTER chip, providing a 3D voxelization of 8mm x 8mm x 1.2mm for approximately 10 cm/MeV-long electron tracks. This work was developed as part of the R&D program of the NEXT collaboration for future detector upgrades in the search of the 0bbnu decay in 136Xe, specifically those based ...

  19. Effects of elevated atmospheric CO2 concentration and temperature on the soil profile methane distribution and diffusion in rice-wheat rotation system.

    Science.gov (United States)

    Yang, Bo; Chen, Zhaozhi; Zhang, Man; Zhang, Heng; Zhang, Xuhui; Pan, Genxing; Zou, Jianwen; Xiong, Zhengqin

    2015-06-01

    The aim of this experiment was to determine the impacts of climate change on soil profile concentrations and diffusion effluxes of methane in a rice-wheat annual rotation ecosystem in Southeastern China. We initiated a field experiment with four treatments: ambient conditions (CKs), CO2 concentration elevated to ~500 μmol/mol (FACE), temperature elevated by ca. 2°C (T) and combined elevation of CO2 concentration and temperature (FACE+T). A multilevel sampling probe was designed to collect the soil gas at four different depths, namely, 7 cm, 15 cm, 30 cm and 50 cm. Methane concentrations were higher during the rice season and decreased with depth, while lower during the wheat season and increased with depth. Compared to CK, mean methane concentration was increased by 42%, 57% and 71% under the FACE, FACE+T and T treatments, respectively, at the 7 cm depth during the rice season (pCO2 concentration and temperature could significantly increase soil profile methane concentrations and their effluxes from a rice-wheat field annual rotation ecosystem (p<0.05). Copyright © 2015. Published by Elsevier B.V.

  20. Long-term effects of changing atmospheric pollution on throughfall, bulk deposition and streamwaters in a Mediterranean forest.

    Science.gov (United States)

    Aguillaume, Laura; Rodrigo, Anselm; Avila, Anna

    2016-02-15

    The abatement programs implanted in Europe to reduce SO2, NO2 and NH3 emissions are here evaluated by analyzing the relationships between emissions in Spain and neighboring countries and atmospheric deposition in a Mediterranean forest in the Montseny mountains (NE Spain) for the last 3decades. A canopy budget model was applied to throughfall data measured during a period of high emissions (1995-1996) and a period of lower emissions (2011-2013) to estimate the changes in dry deposition over this time span. Emissions of SO2 in Spain strongly decreased (77%) and that was reflected in reductions for nssSO4(2-) in precipitation (65% for concentrations and 62% for SO4(2)-S deposition). A lower decline was found for dry deposition (29%). Spanish NO2 emissions increased from 1980 to 1991, remained constant until 2005, and decreased thereafter, a pattern that was paralleled by NO3(-) concentrations in bulk precipitation at Montseny. This pattern seems to be related to a higher share of renewable energies in electricity generation in Spain in recent years. However, dry deposition increased markedly between 1995 and 2012, from 1.3 to 6.7 kg ha(-1) year(-)(1). Differences in meteorology between periods may have had a role, since the recent period was drier thus probably favoring dry deposition. Spanish NH3 emissions increased by 13% between 1980 and 2012 in Spain but NH4(+) concentrations in precipitation and NH4(+)-N deposition showed a decreasing trend (15% reduction) at Montseny, probably linked to the reduction ammonium sulfate and nitrate aerosols to be scavenged by rainfall. NH4(+)-N dry deposition was similar between the compared periods. The N load at Montseny (15-17 kg ha(-1)y ear(-1)) was within the critical load range proposed for Mediterranean sclerophyllous forests (15-17.5 kg ha(-1) year(-1)). The onset of N saturation is suggested by the observed increasing N export in streamwaters. Copyright © 2015 Elsevier B.V. All rights reserved.

  1. Tree bark suber-included particles: A long-term accumulation site for elements of atmospheric origin

    Science.gov (United States)

    Catinon, Mickaël; Ayrault, Sophie; Spadini, Lorenzo; Boudouma, Omar; Asta, Juliette; Tissut, Michel; Ravanel, Patrick

    2011-02-01

    The deposition of atmospheric elements on and into the bark of 4-year-old Fraxinus excelsior L. was studied. The elemental composition of the suber tissue was established through ICP-MS analysis and the presence of solid mineral particles included in this suber was established and described through SEM-EDX. Fractionation of the suber elements mixture was obtained after ashing at 550 °C through successive water (C fraction) and HNO 3 2 M (D fraction) extraction, leading to an insoluble residue mainly composed of the solid mineral particles (E fraction). The triplicated % weight of C, D and E were respectively 34.4 ± 2.7, 64.8 ± 2.7 and 0.8 ± 0.1% of the suber ashes weight. The main component of C was K, of D was Ca. Noticeable amounts of Mg were also observed in D. The E fraction, composed of insoluble particles, was mostly constituted of geogenic products, with elements such as Si, Al, K, Mg, representing primary minerals. E also contained Ca 3(PO 4) 2 and concentrated the main part of Pb and Fe. Moreover, The SEM-EDX analysis evidenced that this fraction also concentrated several types of fly ashes of industrial origin. The study of the distribution between C, D and E was analysed through ICP-MS with respect to their origin. The origin of the elements found in such bark was either geogenic (clay, micas, quartz…), anthropogenic or biogenic (for instance large amounts of solid Ca organic salts having a storage role). As opposed to the E fraction, the C fraction, mainly composed of highly soluble K+ is characteristic of a biological pool of plant origin. In fraction D, the very high amount of Ca++ corresponds to two different origins: biological or acid soluble minerals such as calcite. Furthermore, the D fraction contains the most part of pollutants of anthropic origin such as Zn, Cu, Ni, Co, Cd. As a whole, the fractionation procedure of the suber samples allows to separate elements as a function of their origin but also gives valuable information on

  2. Leaf quality and insect herbivory in model tropical plant communities after long-term exposure to elevated atmospheric CO2.

    Science.gov (United States)

    Arnone, J A; Zaller, J G; Körner, Ch; Ziegler, C; Zandt, H

    1995-09-01

    Results from laboratory feeding experiments have shown that elevated atmospheric carbon dioxide can affect interactions between plants and insect herbivores, primarily through changes in leaf nutritional quality occurring at elevated CO 2 . Very few data are available on insect herbivory in plant communities where insects can choose among species and positions in the canopy in which to feed. Our objectives were to determine the extent to which CO 2 -induced changes in plant communities and leaf nutritional quality may affect herbivory at the level of the entire canopy. We introduced equivalent populations of fourth instar Spodoptera eridania, a lepidopteran generalist, to complex model ecosystems containing seven species of moist tropical plants maintained under low mineral nutrient supply. Larvae were allowed to feed freely for 14 days, by which time they had reached the seventh instar. Prior to larval introductions, plant communities had been continuously exposed to either 340 μl CO 2 l -1 or to 610 μl CO 2 l -1 for 1.5 years. No major shifts in leaf nutritional quality [concentrations of N, total non-structural carbohydrates (TNC), sugar, and starch; ratios of: C/N, TNC/N, sugar/N, starch/N; leaf toughness] were observed between CO 2 treatments for any of the species. Furthermore, no correlations were observed between these measures of leaf quality and leaf biomass consumption. Total leaf area and biomass of all plant communities were similar when caterpillars were introduced. However, leaf biomass of some species was slightly greater-and for other species slightly less (e.g. Cecropia peltata)-in communities exposed to elevated CO 2 . Larvae showed the strongest preference for C. peltata leaves, the plant species that was least abundant in all communites, and fed relatively little on plants species which were more abundant. Thus, our results indicate that leaf tissue quality, as described by these parameters, is not necessarily affected by elevated CO 2 under

  3. Inpainting using airy diffusion

    Science.gov (United States)

    Lorduy Hernandez, Sara

    2015-09-01

    One inpainting procedure based on Airy diffusion is proposed, implemented via Maple and applied to some digital images. Airy diffusion is a partial differential equation with spatial derivatives of third order in contrast with the usual diffusion with spatial derivatives of second order. Airy diffusion generates the Airy semigroup in terms of the Airy functions which can be rewritten in terms of Bessel functions. The Airy diffusion can be used to smooth an image with the corresponding noise elimination via convolution. Also the Airy diffusion can be used to erase objects from an image. We build an algorithm using the Maple package ImageTools and such algorithm is tested using some images. Our results using Airy diffusion are compared with the similar results using standard diffusion. We observe that Airy diffusion generates powerful filters for image processing which could be incorporated in the usual packages for image processing such as ImageJ and Photoshop. Also is interesting to consider the possibility to incorporate the Airy filters as applications for smartphones and smart-glasses.

  4. Long-term trends of black carbon and sulphate aerosol in the Arctic: changes in atmospheric transport and source region emissions

    Directory of Open Access Journals (Sweden)

    D. Hirdman

    2010-10-01

    Full Text Available As a part of the IPY project POLARCAT (Polar Study using Aircraft, Remote Sensing, Surface Measurements and Models, of Climate, Chemistry, Aerosols and Transport and building on previous work (Hirdman et al., 2010, this paper studies the long-term trends of both atmospheric transport as well as equivalent black carbon (EBC and sulphate for the three Arctic stations Alert, Barrow and Zeppelin. We find a general downward trend in the measured EBC concentrations at all three stations, with a decrease of −2.1±0.4 ng m−3 yr−1 (for the years 1989–2008 and −1.4±0.8 ng m−3 yr−1 (2002–2009 at Alert and Zeppelin respectively. The decrease at Barrow is, however, not statistically significant. The measured sulphate concentrations show a decreasing trend at Alert and Zeppelin of −15±3 ng m−3 yr−1 (1985–2006 and −1.3±1.2 ng m−3 yr−1 (1990–2008 respectively, while there is no trend detectable at Barrow.

    To reveal the contribution of different source regions on these trends, we used a cluster analysis of the output of the Lagrangian particle dispersion model FLEXPART run backward in time from the measurement stations. We have investigated to what extent variations in the atmospheric circulation, expressed as variations in the frequencies of the transport from four source regions with different emission rates, can explain the long-term trends in EBC and sulphate measured at these stations. We find that the long-term trend in the atmospheric circulation can only explain a minor fraction of the overall downward trend seen in the measurements of EBC (0.3–7.2% and sulphate (0.3–5.3% at the Arctic stations. The changes in emissions are dominant in explaining the trends. We find that the highest EBC and sulphate concentrations are associated with transport from Northern Eurasia and decreasing emissions in this region drive the

  5. Volatile organic compounds in urban atmospheres: Long-term measurements of ambient air concentrations in differently loaded regions of Leipzig

    Energy Technology Data Exchange (ETDEWEB)

    Knobloch, T.; Asperger, A.; Engewald, W. [University of Leipzig, Institute of Analytical Chemistry, Leipzig (Germany)

    1997-09-01

    For the comprehensive characterization of ambient air concentrations of a broad spectrum of volatile organic compounds (VOCs) an analytical method is described, consisting of adsorptive enrichment, thermal desorption without cryofocusing, and capillary gas chromatographic separation. The method was applied during two-week measuring campaigns in winter and summer 1995, and in the winter of 1996. Long-term sampling was carried out at sampling points in residential areas in the suburbs and near the city center of Leipzig. About 70 VOCs - mainly hydrocarbons from propene to hexadecane - were identified both by GC-MS and chromatographic retention data and quantified after external calibration. Mean values of VOC concentrations obtained during the sampling periods are reported and discussed with regard to the topographical location of the sampling points in the Leipzig area, seasonal variations, and possible emission sources. (orig.) With 7 figs., 3 tabs., 18 refs.

  6. Spatial and temporal distribution of 14C in cellulose in tree rings in Central and Eastern Canada: comparison with long-term atmospheric and environmental data

    International Nuclear Information System (INIS)

    Kotzer, T.G.; Watson, W.L.

    1999-05-01

    Dendrochronologically characterized tree rings from several different species across Central and Eastern Canada and spanning a time range of several decades have been analysed for their 14 C specific activities using oxygen combustion - direct liquid scintillation counting techniques. Carbon-14 specific activities varied between 218 and 439 Bq·kg -1 (±5 to 10%) and yielded a good correlation with the 14 C measured in long-term records of 14 C-in-air values, although 14 C levels in Canada are slightly higher (10 to 20 per mil). An average pre-bomb 14 C value of 225 Bq·kg -1 was obtained from tree rings between 1910 and 1945 which agrees with the value for NBS oxalic acid standard for 'modern' 14 C at 226 Bq·kg -1 . Present-day levels of 14 C in the tree rings are on the order of 250 Bq·kg -1 , indicating that they, like 14 C0 2 -in-air values, have yet to reach 'pre-nuclear testing' levels. Specific activities of 14 C in tree rings from several sites in Canada show no systematic changes with respect to their distance from CANDU heavy-water nuclear power generating stations, suggesting that these stations have had negligible effects on the atmospheric radiocarbon budget for mid-latitudinal North America. The radiocarbon data from the tree rings indicate that atmospheric 14 C has an atmospheric half-time on the order of approximately 15 years, similar to that from other data sets. (author)

  7. Diffusion rates for elevated releases

    International Nuclear Information System (INIS)

    Ramsdell, J.V.

    1983-11-01

    A search of the literature related to diffusion from elevated sources has determined that an adequate data base exists for use in developing parameterizations for estimating diffusion rates for material released from free standing stacks at nuclear power plants. A review of published data analyses indicates that a new parameterization of horizontal diffusion rates specifically for elevated releases is not likely to significantly change the magnitudes of horizontal diffusion coefficients on the average. However, the uncertainties associated with horizontal diffusion coefficient estimates under any given set of atmospheric conditions could be reduced by a new parameterization. Similarly, a new parameterization of vertical diffusion rates would be unlikely to significantly alter the magnitudes of diffusion coefficients for unstable atmospheric conditons. However, for neutral and stable atmospheric conditions, a new parameterization of vertical diffusion rates might increase vertical diffusion coefficients significantly. The increase would move ground-level time-integrated concentration maxima closer to the plant and would increase the maxima. 55 references, 2 figures, 4 tables

  8. Persistent organic pollutants (POPs) in the atmosphere of coastal areas of the Ross Sea, Antarctica: Indications for long-term downward trends.

    Science.gov (United States)

    Pozo, Karla; Martellini, Tania; Corsolini, Simonetta; Harner, Tom; Estellano, Victor; Kukučka, Petr; Mulder, Marie D; Lammel, Gerhard; Cincinelli, Alessandra

    2017-07-01

    Passive air samplers were used to evaluate long-term trends and spatial distribution of trace organic compounds in Antarctica. Duplicate PUF disk samplers were deployed at six automatic weather stations in the coastal area of the Ross sea (East Antarctica), between December 2010 and January 2011, during the XXVI Italian Scientific Research Expedition. Among the investigated persistent organic compounds, Hexachlorobenzene was the most abundant, with air concentrations ranging from 0.8 to 50 pg m -3 . In general, the following decreasing concentration order was found for the air samples analyzed: HCB > PeCB > PCBs > DDTs > HCHs. While HCB concentrations were in the same range as those reported in the atmosphere of other Antarctic sampling areas and did not show a decline, HCHs and DDTs levels were lower or similar to those determined one or two decades ago. In general, the very low concentrations reflected the pristine state of the East Antarctica air. Backward trajectories indicated the prevalence of air masses coming from the Antarctic continent. Local contamination and volatilization from ice were suggested as potential sources for the presence of persistent organic pollutants in the atmosphere. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. Quasi-biennial oscillation in atmospheric ozone, and its possible consequences for damaging UV-B radiation and for determination of long-term ozone trends

    Energy Technology Data Exchange (ETDEWEB)

    Gruzdev, A N [Russian Academy of Sciences, Moscow (Russian Federation). Inst. of Atmospheric Physics

    1996-12-31

    The quasi-biennial oscillation (QBO) in ozone is supposed to be related to the QBO of zonal wind in the tropical stratosphere, with an approximate period of 29 months. Generally speaking, mechanisms of QBO-related effects in the extratropical atmosphere should depend on season and region, resulting in other periodicities (e.g., a 20-month periodicity) due to nonlinear interaction between the `pure` QBO and an annual cycle. Seasonal and regional dependences of QBO-related effects in ozone not only influence the regime of ozone variability itself, but can have important consequences, for example, for interannual changes in biologically active UV-B radiation and for determination of long-term ozone trends. This work is concerned with these problems

  10. Quasi-biennial oscillation in atmospheric ozone, and its possible consequences for damaging UV-B radiation and for determination of long-term ozone trends

    Energy Technology Data Exchange (ETDEWEB)

    Gruzdev, A.N. [Russian Academy of Sciences, Moscow (Russian Federation). Inst. of Atmospheric Physics

    1995-12-31

    The quasi-biennial oscillation (QBO) in ozone is supposed to be related to the QBO of zonal wind in the tropical stratosphere, with an approximate period of 29 months. Generally speaking, mechanisms of QBO-related effects in the extratropical atmosphere should depend on season and region, resulting in other periodicities (e.g., a 20-month periodicity) due to nonlinear interaction between the `pure` QBO and an annual cycle. Seasonal and regional dependences of QBO-related effects in ozone not only influence the regime of ozone variability itself, but can have important consequences, for example, for interannual changes in biologically active UV-B radiation and for determination of long-term ozone trends. This work is concerned with these problems

  11. Responses of soil Collembola to long-term atmospheric CO2 enrichment in a mature temperate forest

    International Nuclear Information System (INIS)

    Xu Guoliang; Fu Shenglei; Schleppi, Patrick; Li Maihe

    2013-01-01

    Responses of Collembola to 7 years of CO 2 enrichment (550 ppm) in a Swiss free-air CO 2 enrichment (FACE) experiment in a forest with 80- to 120-year-old trees were investigated in this study. Contrary to our expectations, increased CO 2 caused a significant decrease in Collembola numbers, including a significant decrease in euedaphic Collembola. Increased CO 2 , however, did not affect community group richness. Collembola biomass was not significantly changed by CO 2 enrichment, regardless of whether it was considered in terms of the total community, life-strategy groups, or individual species (with an exception of Mesaphorura krausbaueri). The reason for this is that CO 2 enrichment caused a general increase in individual body size, which compensated for reduced abundances. The results are consistent with the idea that the rhizosphere is important for soil fauna, and the combination of reduced fine root growth and increased soil moisture might trigger a reduction in Collembola abundance. - Highlights: ► Increased CO 2 caused a significant decrease in Collembola abundance. ► Increased CO 2 caused a significant decrease in euedaphic Collembola. ► Collembola body size tended to be larger. ► A decrease in fine roots biomass might trigger the reduction in Collembola. - Seven years of CO 2 enrichment caused a significant decrease in Collembola abundance, especially in euedaphic species.

  12. Anisotropy in "isotropic diffusion" measurements due to nongaussian diffusion

    DEFF Research Database (Denmark)

    Jespersen, Sune Nørhøj; Olesen, Jonas Lynge; Ianuş, Andrada

    2017-01-01

    Designing novel diffusion-weighted NMR and MRI pulse sequences aiming to probe tissue microstructure with techniques extending beyond the conventional Stejskal-Tanner family is currently of broad interest. One such technique, multidimensional diffusion MRI, has been recently proposed to afford...... model-free decomposition of diffusion signal kurtosis into terms originating from either ensemble variance of isotropic diffusivity or microscopic diffusion anisotropy. This ability rests on the assumption that diffusion can be described as a sum of multiple Gaussian compartments, but this is often...

  13. Long-term trend in ground-based air temperature and its responses to atmospheric circulation and anthropogenic activity in the Yangtze River Delta, China

    Science.gov (United States)

    Peng, Xia; She, Qiannan; Long, Lingbo; Liu, Min; Xu, Qian; Zhang, Jiaxin; Xiang, Weining

    2017-10-01

    The Yangtze River Delta (YRD), including Shanghai City, Jiangsu and Zhejiang Provinces, is the largest metropolitan region in China. In the past decades, the region has experienced massive urbanization and detrimentally affected the environment in the region. Identifying the spatio-temporal variations of climate change and its influencing mechanism in the YRD is an important task for assessing their impacts on the local society and ecosystem. Based on long-term (1958-2014) observation data of meteorological stations, three temperature indices, i.e. extreme maximum temperature (TXx), extreme minimum temperature (TNn), and mean temperature (TMm), were selected and spatialized with climatological calculations and spatial techniques. Evolution and spatial heterogeneity of three temperature indices over YRD as well as their links to atmospheric circulation and anthropogenic activity were investigated. In the whole YRD, a statistically significant overall uptrend could be detected in three temperature indices with the Mann-Kendall (M-K) trend test method. The linear increasing trend for TMm was 0.31 °C/10 a, which was higher than the global average (0.12 °C/10 a during 1951-2012). For TXx and TNn, the increasing rates were 0.41 °C/10 a and 0.52 °C/10 a. Partial correlation analysis indicated that TMm was more related with TXx (rp = 0.68, p < 0.001) than TNn (rp = 0.48, p < 0.001). Furthermore, it was detected with M-K analysis at pixel scale that 62.17%, 96.75% and 97.05% of the areas in the YRD showed significant increasing trends for TXx, TNn and TMm, respectively. The increasing trend was more obvious in the southern mountainous areas than the northern plains areas. Further analysis indicated that the variation of TXx over YRD was mainly influenced by anthropogenic activities (e.g. economic development), while TNn was more affected by atmospheric circulations (e.g., the Eurasian zonal circulation index (EAZ) and the cold air activity index (CA)). For TMm, it was a

  14. Sources of atmospheric aerosol from long-term measurements (5 years) of chemical composition in Athens, Greece.

    Science.gov (United States)

    Paraskevopoulou, D; Liakakou, E; Gerasopoulos, E; Mihalopoulos, N

    2015-09-15

    To identify the sources of aerosols in Greater Athens Area (GAA), a total of 1510 daily samples of fine (PM 2.5) and coarse (PM 10-2,5) aerosols were collected at a suburban site (Penteli), during a five year period (May 2008-April 2013) corresponding to the period before and during the financial crisis. In addition, aerosol sampling was also conducted in parallel at an urban site (Thissio), during specific, short-term campaigns during all seasons. In all these samples mass and chemical composition measurements were performed, the latest only at the fine fraction. Particulate organic matter (POM) and ionic masses (IM) are the main contributors of aerosol mass, equally contributing by accounting for about 24% of the fine aerosol mass. In the IM, nss-SO4(-2) is the prevailing specie followed by NO3(-) and NH4(+) and shows a decreasing trend during the 2008-2013 period similar to that observed for PM masses. The contribution of water in fine aerosol is equally significant (21 ± 2%), while during dust transport, the contribution of dust increases from 7 ± 2% to 31 ± 9%. Source apportionment (PCA and PMF) and mass closure exercises identified the presence of six sources of fine aerosols: secondary photochemistry, primary combustion, soil, biomass burning, sea salt and traffic. Finally, from winter 2012 to winter 2013 the contribution of POM to the urban aerosol mass is increased by almost 30%, reflecting the impact of wood combustion (dominant fuel for domestic heating) to air quality in Athens, which massively started in winter 2013. Copyright © 2015 Elsevier B.V. All rights reserved.

  15. Long-term visibility variation in Athens (1931–2013: a proxy for local and regional atmospheric aerosol loads

    Directory of Open Access Journals (Sweden)

    D. Founda

    2016-09-01

    Full Text Available This study explores the interdecadal variability and trends of surface horizontal visibility at the urban area of Athens from 1931 to 2013, using the historical archives of the National Observatory of Athens (NOA. A prominent deterioration of visibility in the city was detected, with the long-term linear trend amounting to −2.8 km decade−1 (p < 0.001, over the entire study period. This was not accompanied by any significant trend in relative humidity or precipitation over the same period. A slight recovery of visibility levels seems to be established in the recent decade (2004–2013. It was found that very good visibility (>  20 km occurred at a frequency of 34 % before the 1950s, while this percentage drops to just 2 % during the decade 2004–2013. The rapid impairment of the visual air quality in Athens around the 1950s points to the increased levels of air pollution on a local and/or regional scale, related to high urbanization rates and/or increased anthropogenic emissions on a global scale at that period. Visibility was found to be negatively/positively correlated with relative humidity/wind speed, the correlation being statistically valid at certain periods. Wind regime and mainly wind direction and corresponding air mass origin were found to highly control visibility levels in Athens. The comparison of visibility variation in Athens and at a non-urban reference site on Crete island revealed similar negative trends over the common period of observations. This suggests that apart local sources, visibility in Athens is highly determined by aerosol load of regional origin. AVHRR and MODIS satellite-derived aerosol optical depth (AOD retrievals over Athens and surface measurements of PM10 confirmed the relation of visibility to aerosol load.

  16. Mobility particle size spectrometers: harmonization of technical standards and data structure to facilitate high quality long-term observations of atmospheric particle number size distributions

    Directory of Open Access Journals (Sweden)

    A. Wiedensohler

    2012-03-01

    Full Text Available Mobility particle size spectrometers often referred to as DMPS (Differential Mobility Particle Sizers or SMPS (Scanning Mobility Particle Sizers have found a wide range of applications in atmospheric aerosol research. However, comparability of measurements conducted world-wide is hampered by lack of generally accepted technical standards and guidelines with respect to the instrumental set-up, measurement mode, data evaluation as well as quality control. Technical standards were developed for a minimum requirement of mobility size spectrometry to perform long-term atmospheric aerosol measurements. Technical recommendations include continuous monitoring of flow rates, temperature, pressure, and relative humidity for the sheath and sample air in the differential mobility analyzer.

    We compared commercial and custom-made inversion routines to calculate the particle number size distributions from the measured electrical mobility distribution. All inversion routines are comparable within few per cent uncertainty for a given set of raw data.

    Furthermore, this work summarizes the results from several instrument intercomparison workshops conducted within the European infrastructure project EUSAAR (European Supersites for Atmospheric Aerosol Research and ACTRIS (Aerosols, Clouds, and Trace gases Research InfraStructure Network to determine present uncertainties especially of custom-built mobility particle size spectrometers. Under controlled laboratory conditions, the particle number size distributions from 20 to 200 nm determined by mobility particle size spectrometers of different design are within an uncertainty range of around ±10% after correcting internal particle losses, while below and above this size range the discrepancies increased. For particles larger than 200 nm, the uncertainty range increased to 30%, which could not be explained. The network reference mobility spectrometers with identical design agreed within ±4% in the

  17. Effect of surface characteristics on diffuse reflection radiation at lambda=0. 40. mu. m

    Energy Technology Data Exchange (ETDEWEB)

    Takashima, T [Atmospheric Environment Service, Downsview, Ontario (Canada)

    1976-08-01

    The diffuse radiation in the upward direction at the top and at an internal level of an inhomogeneous atmosphere is computed at lambda=0.40 ..mu..m. The surface is assumed to reflect light in accordance with a hybrid mode of a diffuse and specular reflector. The objective is to estimate the effect of underlying surface characteristics in terms of the diffuse radiation field. By making use of these results, accuracy in monitoring the atmospheric aerosols would be increased for the use of remote sensing satellite techniques. Junge power law (..gamma..*=3) is adopted for the size distribution of aerosols (1963), while the data given by McClatchy et al. (1971) is used for the number density of aerosols with height distribution. It is noted from the computations that the diffuse reflection radiation is affected by the surface characteristics, even if the albedo of the surface is a fixed constant and very small.

  18. Staging atmospheres

    DEFF Research Database (Denmark)

    Bille, Mikkel; Bjerregaard, Peter; Sørensen, Tim Flohr

    2015-01-01

    The article introduces the special issue on staging atmospheres by surveying the philosophical, political and anthropological literature on atmosphere, and explores the relationship between atmosphere, material culture, subjectivity and affect. Atmosphere seems to occupy one of the classic...

  19. Modelling of Innovation Diffusion

    Directory of Open Access Journals (Sweden)

    Arkadiusz Kijek

    2010-01-01

    Full Text Available Since the publication of the Bass model in 1969, research on the modelling of the diffusion of innovation resulted in a vast body of scientific literature consisting of articles, books, and studies of real-world applications of this model. The main objective of the diffusion model is to describe a pattern of spread of innovation among potential adopters in terms of a mathematical function of time. This paper assesses the state-of-the-art in mathematical models of innovation diffusion and procedures for estimating their parameters. Moreover, theoretical issues related to the models presented are supplemented with empirical research. The purpose of the research is to explore the extent to which the diffusion of broadband Internet users in 29 OECD countries can be adequately described by three diffusion models, i.e. the Bass model, logistic model and dynamic model. The results of this research are ambiguous and do not indicate which model best describes the diffusion pattern of broadband Internet users but in terms of the results presented, in most cases the dynamic model is inappropriate for describing the diffusion pattern. Issues related to the further development of innovation diffusion models are discussed and some recommendations are given. (original abstract

  20. Development of a coupled diffusion denuder system combined with gas chromatography/mass spectrometry for the separation and quantification of molecular iodine and the activated iodine compounds iodine monochloride and hypoiodous acid in the marine atmosphere.

    Science.gov (United States)

    Huang, Ru-Jin; Hoffmann, Thorsten

    2009-03-01

    This study concerns the development of a coupled diffusion denuder system capable of separating and quantifying gaseous molecular iodine (I(2)) and two other highly reactive iodine species, ICl and HOI, which are collectively named activated iodine compounds (AIC). Both I(2) and AIC are key species in the atmospheric chemistry of iodine. 1,3,5-Trimethoxybenzene (1,3,5-TMB)- and alpha-cyclodextrin/(129)I(-) (alpha-CD/(129)I(-))-coated denuders proved to be suitable for the collection of gaseous AIC and I(2), respectively. The experimental collection efficiencies for AIC (tested as ICl) and I(2) agreed well with the theoretical values for gas flow rates in the range between 300 and 1800 mL min(-1). The coupled denuder system (1,3,5-TMB-coated denuder as front-denuder coupled upstream of an alpha-CD/(129)I(-)-coated denuder) was applied successfully to separate test gas mixtures of ICl and I(2) at various mixing ratios in the laboratory. The operation of both denuder systems was demonstrated to be independent of relative humidity (0-100%) and storage period (at least 2 weeks prior to and after sampling). Detection limits were achieved at sub-parts-per-trillion-by-volume (sub-pptv) level. The presented method provides a reliable and practical approach for the speciation of gaseous iodine compounds. In addition, we report for the first time ambient air measurements of AIC mixing ratios, carried out at the atmospheric research station in Mace Head, Ireland. A maximum concentration of AIC of 30.2 pptv was observed for nighttime measurements and 6.0 pptv for daytime measurements. A similar diurnal pattern was found for I(2) with an average concentration level of 23.2 pptv during daytime and 85.1 pptv during nighttime, indicating a strong correlation with AIC.

  1. Hydrodynamic escape from planetary atmospheres

    Science.gov (United States)

    Tian, Feng

    Hydrodynamic escape is an important process in the formation and evolution of planetary atmospheres. Due to the existence of a singularity point near the transonic point, it is difficult to find transonic steady state solutions by solving the time-independent hydrodynamic equations. In addition to that, most previous works assume that all energy driving the escape flow is deposited in one narrow layer. This assumption not only results in less accurate solutions to the hydrodynamic escape problem, but also makes it difficult to include other chemical and physical processes in the hydrodynamic escape models. In this work, a numerical model describing the transonic hydrodynamic escape from planetary atmospheres is developed. A robust solution technique is used to solve the time dependent hydrodynamic equations. The method has been validated in an isothermal atmosphere where an analytical solution is available. The hydrodynamic model is applied to 3 cases: hydrogen escape from small orbit extrasolar planets, hydrogen escape from a hydrogen rich early Earth's atmosphere, and nitrogen/methane escape from Pluto's atmosphere. Results of simulations on extrasolar planets are in good agreement with the observations of the transiting extrasolar planet HD209458b. Hydrodynamic escape of hydrogen from other hypothetical close-in extrasolar planets are simulated and the influence of hydrogen escape on the long-term evolution of these extrasolar planets are discussed. Simulations on early Earth suggest that hydrodynamic escape of hydrogen from a hydrogen rich early Earth's atmosphere is about two orders magnitude slower than the diffusion limited escape rate. A hydrogen rich early Earth's atmosphere could have been maintained by the balance between the hydrogen escape and the supply of hydrogen into the atmosphere by volcanic outgassing. Origin of life may have occurred in the organic soup ocean created by the efficient formation of prebiotic molecules in the hydrogen rich early

  2. A Synthetic Method for Atmospheric Diffusion Simulation and Environmental Impact Assessment of Accidental Pollution in the Chemical Industry in a WEBGIS Context

    Directory of Open Access Journals (Sweden)

    Haochen Ni

    2014-09-01

    Full Text Available The chemical industry poses a potential security risk to factory personnel and neighboring residents. In order to mitigate prospective damage, a synthetic method must be developed for an emergency response. With the development of environmental numeric simulation models, model integration methods, and modern information technology, many Decision Support Systems (DSSs have been established. However, existing systems still have limitations, in terms of synthetic simulation and network interoperation. In order to resolve these limitations, the matured simulation model for chemical accidents was integrated into the WEB Geographic Information System (WEBGIS platform. The complete workflow of the emergency response, including raw data (meteorology information, and accident information management, numeric simulation of different kinds of accidents, environmental impact assessments, and representation of the simulation results were achieved. This allowed comprehensive and real-time simulation of acute accidents in the chemical industry. The main contribution of this paper is that an organizational mechanism of the model set, based on the accident type and pollutant substance; a scheduling mechanism for the parallel processing of multi-accident-type, multi-accident-substance, and multi-simulation-model; and finally a presentation method for scalar and vector data on the web browser on the integration of a WEB Geographic Information System (WEBGIS platform. The outcomes demonstrated that this method could provide effective support for deciding emergency responses of acute chemical accidents.

  3. A synthetic method for atmospheric diffusion simulation and environmental impact assessment of accidental pollution in the chemical industry in a WEBGIS context.

    Science.gov (United States)

    Ni, Haochen; Rui, Yikang; Wang, Jiechen; Cheng, Liang

    2014-09-05

    The chemical industry poses a potential security risk to factory personnel and neighboring residents. In order to mitigate prospective damage, a synthetic method must be developed for an emergency response. With the development of environmental numeric simulation models, model integration methods, and modern information technology, many Decision Support Systems (DSSs) have been established. However, existing systems still have limitations, in terms of synthetic simulation and network interoperation. In order to resolve these limitations, the matured simulation model for chemical accidents was integrated into the WEB Geographic Information System (WEBGIS) platform. The complete workflow of the emergency response, including raw data (meteorology information, and accident information) management, numeric simulation of different kinds of accidents, environmental impact assessments, and representation of the simulation results were achieved. This allowed comprehensive and real-time simulation of acute accidents in the chemical industry. The main contribution of this paper is that an organizational mechanism of the model set, based on the accident type and pollutant substance; a scheduling mechanism for the parallel processing of multi-accident-type, multi-accident-substance, and multi-simulation-model; and finally a presentation method for scalar and vector data on the web browser on the integration of a WEB Geographic Information System (WEBGIS) platform. The outcomes demonstrated that this method could provide effective support for deciding emergency responses of acute chemical accidents.

  4. A Synthetic Method for Atmospheric Diffusion Simulation and Environmental Impact Assessment of Accidental Pollution in the Chemical Industry in a WEBGIS Context

    Science.gov (United States)

    Ni, Haochen; Rui, Yikang; Wang, Jiechen; Cheng, Liang

    2014-01-01

    The chemical industry poses a potential security risk to factory personnel and neighboring residents. In order to mitigate prospective damage, a synthetic method must be developed for an emergency response. With the development of environmental numeric simulation models, model integration methods, and modern information technology, many Decision Support Systems (DSSs) have been established. However, existing systems still have limitations, in terms of synthetic simulation and network interoperation. In order to resolve these limitations, the matured simulation model for chemical accidents was integrated into the WEB Geographic Information System (WEBGIS) platform. The complete workflow of the emergency response, including raw data (meteorology information, and accident information) management, numeric simulation of different kinds of accidents, environmental impact assessments, and representation of the simulation results were achieved. This allowed comprehensive and real-time simulation of acute accidents in the chemical industry. The main contribution of this paper is that an organizational mechanism of the model set, based on the accident type and pollutant substance; a scheduling mechanism for the parallel processing of multi-accident-type, multi-accident-substance, and multi-simulation-model; and finally a presentation method for scalar and vector data on the web browser on the integration of a WEB Geographic Information System (WEBGIS) platform. The outcomes demonstrated that this method could provide effective support for deciding emergency responses of acute chemical accidents. PMID:25198686

  5. Effect of a short-term HAART on SIV load in macaque tissues is dependent on time of initiation and antiviral diffusion

    Directory of Open Access Journals (Sweden)

    Durand-Gasselin Lucie

    2010-09-01

    Full Text Available Abstract Background HIV reservoirs are rapidly established after infection, and the effect of HAART initiated very early during acute infection on HIV reservoirs remains poorly documented, particularly in tissue known to actively replicate the virus. In this context, we used the model of experimental infection of macaques with pathogenic SIV to assess in different tissues: (i the effect of a short term HAART initiated at different stages during acute infection on viral dissemination and replication, and (ii the local concentration of antiviral drugs. Results Here, we show that early treatment with AZT/3TC/IDV initiated either within 4 hours after intravenous infection of macaques with SIVmac251 (as a post exposure prophylaxis or before viremia peak (7 days post-infection [pi], had a strong impact on SIV production and dissemination in all tissues but did not prevent infection. When treatment was initiated after the viremia peak (14 days pi or during early chronic infection (150 days pi, significant viral replication persists in the peripheral lymph nodes and the spleen of treated macaques despite a strong effect of treatment on viremia and gut associated lymphoid tissues. In these animals, the level of virus persistence in tissues was inversely correlated with local concentrations of 3TC: high concentrations of 3TC were measured in the gut whereas low concentrations were observed in the secondary lymphoid tissues. IDV, like 3TC, showed much higher concentration in the colon than in the spleen. AZT concentration was below the quantification threshold in all tissues studied. Conclusions Our results suggest that limited antiviral drug diffusion in secondary lymphoid tissues may allow persistent viral replication in these tissues and could represent an obstacle to HIV prevention and eradication.

  6. Rapid and long-term effects of water deficit on gas exchange and hydraulic conductance of silver birch trees grown under varying atmospheric humidity.

    Science.gov (United States)

    Sellin, Arne; Niglas, Aigar; Õunapuu-Pikas, Eele; Kupper, Priit

    2014-03-24

    Effects of water deficit on plant water status, gas exchange and hydraulic conductance were investigated in Betula pendula under artificially manipulated air humidity in Eastern Estonia. The study was aimed to broaden an understanding of the ability of trees to acclimate with the increasing atmospheric humidity predicted for northern Europe. Rapidly-induced water deficit was imposed by dehydrating cut branches in open-air conditions; long-term water deficit was generated by seasonal drought. The rapid water deficit quantified by leaf (ΨL) and branch water potentials (ΨB) had a significant (P gas exchange parameters, while inclusion of ΨB in models resulted in a considerably better fit than those including ΨL, which supports the idea that stomatal openness is regulated to prevent stem rather than leaf xylem dysfunction. Under moderate water deficit (ΨL≥-1.55 MPa), leaf conductance to water vapour (gL), transpiration rate and leaf hydraulic conductance (KL) were higher (P water deficit (ΨLwater availability, i.e. due to higher soil water potential in H treatment. Two functional characteristics (gL, KL) exhibited higher (P water deficit in trees grown under increased air humidity. The experiment supported the hypothesis that physiological traits in trees acclimated to higher air humidity exhibit higher sensitivity to rapid water deficit with respect to two characteristics - leaf conductance to water vapour and leaf hydraulic conductance. Disproportionate changes in sensitivity of stomatal versus leaf hydraulic conductance to water deficit will impose greater risk of desiccation-induced hydraulic dysfunction on the plants, grown under high atmospheric humidity, in case of sudden weather fluctuations, and might represent a potential threat in hemiboreal forest ecosystems. There is no trade-off between plant hydraulic capacity and photosynthetic water-use efficiency on short time scale.

  7. Integration of measurements with atmospheric dispersion models: Source term estimation for dispersal of (239)Pu due to non-nuclear detonation of high explosive

    Science.gov (United States)

    Edwards, L. L.; Harvey, T. F.; Freis, R. P.; Pitovranov, S. E.; Chernokozhin, E. V.

    1992-10-01

    The accuracy associated with assessing the environmental consequences of an accidental release of radioactivity is highly dependent on our knowledge of the source term characteristics and, in the case when the radioactivity is condensed on particles, the particle size distribution, all of which are generally poorly known. This paper reports on the development of a numerical technique that integrates the radiological measurements with atmospheric dispersion modeling. This results in a more accurate particle-size distribution and particle injection height estimation when compared with measurements of high explosive dispersal of (239)Pu. The estimation model is based on a non-linear least squares regression scheme coupled with the ARAC three-dimensional atmospheric dispersion models. The viability of the approach is evaluated by estimation of ADPIC model input parameters such as the ADPIC particle size mean aerodynamic diameter, the geometric standard deviation, and largest size. Additionally we estimate an optimal 'coupling coefficient' between the particles and an explosive cloud rise model. The experimental data are taken from the Clean Slate 1 field experiment conducted during 1963 at the Tonopah Test Range in Nevada. The regression technique optimizes the agreement between the measured and model predicted concentrations of (239)Pu by varying the model input parameters within their respective ranges of uncertainties. The technique generally estimated the measured concentrations within a factor of 1.5, with the worst estimate being within a factor of 5, very good in view of the complexity of the concentration measurements, the uncertainties associated with the meteorological data, and the limitations of the models. The best fit also suggest a smaller mean diameter and a smaller geometric standard deviation on the particle size as well as a slightly weaker particle to cloud coupling than previously reported.

  8. Integration of measurements with atmospheric dispersion models: Source term estimation for dispersal of 239Pu due to non- nuclear detonation of high explosive

    International Nuclear Information System (INIS)

    Edwards, L.L.; Harvey, T.F.; Freis, R.P.; Pitovranov, S.E.; Chernokozhin, E.V.

    1992-10-01

    The accuracy associated with assessing the environmental consequences of an accidental release of radioactivity is highly dependent on our knowledge of the source term characteristics and, in the case when the radioactivity is condensed on particles, the particle size distribution, all of which are generally poorly known. This paper reports on the development of a numerical technique that integrates the radiological measurements with atmospheric dispersion modeling. This results in a more accurate particle-size distribution and particle injection height estimation when compared with measurements of high explosive dispersal of 239 Pu. The estimation model is based on a non-linear least squares regression scheme coupled with the ARAC three-dimensional atmospheric dispersion models. The viability of the approach is evaluated by estimation of ADPIC model input parameters such as the ADPIC particle size mean aerodynamic diameter, the geometric standard deviation, and largest size. Additionally we estimate an optimal ''coupling coefficient'' between the particles and an explosive cloud rise model. The experimental data are taken from the Clean Slate 1 field experiment conducted during 1963 at the Tonopah Test Range in Nevada. The regression technique optimizes the agreement between the measured and model predicted concentrations of 239 Pu by varying the model input parameters within their respective ranges of uncertainties. The technique generally estimated the measured concentrations within a factor of 1.5, with the worst estimate being within a factor of 5, very good in view of the complexity of the concentration measurements, the uncertainties associated with the meteorological data, and the limitations of the models. The best fit also suggest a smaller mean diameter and a smaller geometric standard deviation on the particle size as well as a slightly weaker particle to cloud coupling than previously reported

  9. Effects of salinity and short-term elevated atmospheric CO2 on the chemical equilibrium between CO2 fixation and photosynthetic electron transport of Stevia rebaudiana Bertoni.

    Science.gov (United States)

    Hussin, Sayed; Geissler, Nicole; El-Far, Mervat M M; Koyro, Hans-Werner

    2017-09-01

    The effect of water salinity on plant growth and photosynthetic traits of Stevia rebaudiana was investigated to determine its level and mechanisms of salinity tolerance. It was also attempted to assess how short-term elevated CO 2 concentration would influence the boundaries and mechanisms of its photosynthetic capacity. The plants were grown in gravel/hydroponic system under controlled greenhouse conditions and irrigated with four different salinity levels (0, 25, 50 and 100 mol m -3 NaCl). Low salinity did not significantly alter the plant fresh weight, which was substantially decreased by 67% at high salinity treatment. Salinity tolerance threshold was reached at 50 mol m -3  NaCl while C50 was between 50 and 100 mol m -3  NaCl, indicating that S. rebaudiana is a moderate salt tolerant species. Salt-induced growth reduction was apparently linked to a significant decline of about 47% in the photosynthetic rates (A net ) at high salinity treatment, leading consequently to a disequilibrium between CO 2 -assimilation and electron transport rates (indicated by enhanced ETR max /A gross ratio). Elevated atmospheric CO 2 enhanced CO 2 assimilation rates by 65% and 80% for control and high-salt-stressed plants respectively, likely due to significant increases in intercellular CO 2 concentration (indicated by enhanced C i /C a ). The priority for Stevia under elevated atmospheric CO 2 was not to save water but to maximize photosynthesis so that the PWUE was progressively improved and the threat of oxidative stress was diminished (decline in ETR max /A gross ). The results imply that elevated CO 2 level could ameliorate some of the detrimental effects of salinity, conferring higher tolerance and survival of S. rebaudiana, a highlydesired feature with the forthcoming era of global changes. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  10. A decade of monitoring at Swiss Long-Term Forest Ecosystem Research (LWF) sites: can we observe trends in atmospheric acid deposition and in soil solution acidity?

    Science.gov (United States)

    Pannatier, Elisabeth Graf; Thimonier, Anne; Schmitt, Maria; Walthert, Lorenz; Waldner, Peter

    2011-03-01

    Trends in atmospheric acid deposition and in soil solution acidity from 1995 or later until 2007 were investigated at several forest sites throughout Switzerland to assess the effects of air pollution abatements on deposition and the response of the soil solution chemistry. Deposition of the major elements was estimated from throughfall and bulk deposition measurements at nine sites of the Swiss Long-Term Forest Ecosystem Research network (LWF) since 1995 or later. Soil solution was measured at seven plots at four soil depths since 1998 or later. Trends in the molar ratio of base cations to aluminum (BC/Al) in soil solutions and in concentrations and fluxes of inorganic N (NO(3)-N + NH(4)-N), sulfate (SO(4)-S), and base cations (BC) were used to detect changes in soil solution chemistry. Acid deposition significantly decreased at three out of the nine study sites due to a decrease in total N deposition. Total SO(4)-S deposition decreased at the nine sites, but due to the relatively low amount of SO(4)-S load compared to N deposition, it did not contribute to decrease acid deposition significantly. No trend in total BC deposition was detected. In the soil solution, no trend in concentrations and fluxes of BC, SO(4)-S, and inorganic N were found at most soil depths at five out of the seven sites. This suggests that the soil solution reacted very little to the changes in atmospheric deposition. A stronger reduction in base cations compared to aluminum was detected at two sites, which might indicate that acidification of the soil solution was proceeding faster at these sites.

  11. Airborne heavy metals in two cities of North Rhine Westphalia - Performing inhalation cancer risk assessment in terms of atmospheric circulation.

    Science.gov (United States)

    Dimitriou, Konstantinos; Kassomenos, Pavlos

    2017-11-01

    The main objective of this study was to examine the levels of four heavy metals (As, Cd, Pb and Ni) in PM 10 samples collected in two urban background stations in Dortmund and Bielefeld, in relation to atmospheric circulation. Pollution roses, Conditional Probability Function (CPF) roses and backward air mass trajectory clusters were used to identify air currents associated with the importation of PM 10 and of the included metal constituents. In addition, PM 10 , NO 2 , SO 2 , O 3 , As, Cd, Ni and Pb concentrations were analyzed by a Principal Component Analysis (PCA) to reveal major local emission sources of PM 10 metal content. Traffic was the main emitter of PM 10 , As, Cd, and Pb in both cities, highlighting the existence of non-negligible lead quantities in unleaded gasoline, whilst nickel emissions were associated with heavy fuel oil combustion in industries and primarily for domestic heating. The created CPF roses and trajectory clusters were in good agreement, clearly revealing that eastern air currents enriched the locally produced PM 10 load with additional aerosols from Eastern Europe. The concentrations of arsenic and cadmium were also enhanced by the arrival of air parcels from the East, indicating the anthropogenic origin of the exogenous aerosols due to combustion. The induced cancer risk (CR inh ) for adults, due to inhalation of individual metal constituents, was also estimated in terms of atmospheric circulation, indicating higher risk in Dortmund than in Bielefeld. CR inh values for arsenic exceeded the limit of 1 × 10 -6 in both cities, primarily during the influence of eastern circulation. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Influence of wildfires on atmospheric composition and carbon uptake of forest ecosystems in Central Siberia: the establishing of a long-term post-fire monitoring system

    Science.gov (United States)

    Panov, Alexey; Chi, Xuguang; Winderlich, Jan; Prokushkin, Anatoly; Bryukhanov, Alexander; Korets, Mikhail; Ponomarev, Evgenii; Timokhina, Anastasya; Andreae, Meinrat O.; Heimann, Martin

    2014-05-01

    Calculations of direct emissions of greenhouse gases from boreal wildfires remain uncertain due to problems with emission factors, available carbon, and imprecise estimates of burned areas. Even more varied and sparse are accurate in situ calculations of temporal changes in boreal forest carbon dynamics following fire. Linking simultaneous instrumental atmospheric observations, GIS-based estimates of burned areas, and ecosystem carbon uptake calculations is vital to fill this knowledge gap. Since 2006 the Zotino Tall Tower Observatory (ZOTTO; www.zottoproject.org) a research platform for large-scale climatic observations is operational in Central Siberia (60°48'N, 89°21'E). The data of ongoing greenhouse gases measurements at the tower are used in atmospheric inversions studies to infer the distribution of carbon sinks and sources over central Northern Eurasia. We present our contribution to reducing uncertainties in estimates of fire influence on atmospheric composition and post-fire ecosystem carbon uptake deduced from the large-scale fires that happened in 2012 in the tall tower footprint area. The burned areas were estimated from Landsat ETM 5,8 satellite images, while fires were detected from Terra/Aqua MODIS satellite data. The magnitude of ecological change caused by fires ("burn severity") was measured and mapped with a Normalized Burn Ratio (NBR) index and further calibrated by a complementary field based Composite Burn Index (CBI). Measures of fire radiative power (FRP) index provided information on fire heat release intensity and on the amount and completeness of biomass combustion. Based on the analyzed GIS data, the system of study plots was established in the 5 dominating ecosystem types for a long-term post-fire monitoring. On the plots the comprehensive estimation of ecosystem parameters and carbon pools and their mapping was organized with a laser-based field instrumentation system. The work was supported financially by ISTC Project # 2757p

  13. Contribution of the diffusion-weighted MRI in the diagnosis and follow-up of encephalopathy caused by maple syrup urine disease in a full-term newborn

    International Nuclear Information System (INIS)

    Ferraz-Filho, Jose Roberto Lopes; Floriano, Valdeci Helio; Quirici, Marcelo Bianco; Souza, Antonio Soares; Albuquerque, Regina Pires de

    2009-01-01

    The purpose of this case report is to show conventional MRI and diffusion-weighted imaging (DWI) findings of the different evolutionary phases in MSUD (Maple syrup urine disease) of a newborn that evolved with brain white matter lesions (author)

  14. Positron annihilation in solids: positronium diffusion; Annihilation du positon dans les solides diffusion du positonium

    Energy Technology Data Exchange (ETDEWEB)

    Paulin, R [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1969-04-01

    The existence of two slow components in life-time spectrum of positron annihilation in silicium, aluminium and alkaline-earth oxides powders is established. These two long mean-lives {approx_equal} 10{sup -9} s and {approx_equal} 10{sup -7} s result from annihilation, inside and outside the grains respectively, of ortho-positronium formed in defects present in ionic crystals investigated. Dynamic behaviour of Ps, so revealed, is analyzed in terms of diffusion in excellent agreement with experiment. Diffusion constants of the order of 10{sup -4} cm{sup 2} sec{sup -1} and mean path before annihilation from 50 to 300 Angstrom are measured. From 100 to 500 K the temperature influence upon diffusion process is effective only in SiO{sub 2} where activation energy is found about 10{sup -2} eV. The p-Ps zero point energy evaluated by angular correlation gives the order of magnitude for defects dimensions and diffusion mean-time. Finally, o-Ps behaviour in space between grains, where its interaction with atmospheric gases can be only detected, is analysed. (author) [French] Nous mettons en evidence l'existence de deux composantes lentes dans le spectre de temps de vie du positon avant annihilation dans des poudres d'oxydes alcalinoterreux d'alumine et de silice. Ces deux longues vies moyennes {approx_equal} 10{sup -9} s et {approx_equal} 10{sup -7} s resultent respectivement de l'annihilation a l'interieur et a l'exterieur des grains de l'ortho-positonium forme dans certains defauts presents dans les cristaux ioniques etudies. L'analyse des proprietes dynamiques du Ps ainsi revelees, est effectuee en termes de diffusion en excellent accord avec l'experience. Des constantes de diffusion de l'ordre de 10{sup -4} cm{sup 2} sec{sup -1} et des parcours moyens avant annihilation variant de 50 a 300 Angstrom sont ainsi mesures. Entre 100 et 500 K l'influence de la temperature sur le processus de diffusion n'est sensible que dans SiO{sub 2} ou l'energie d'activation est trouvee

  15. Positron annihilation in solids: positronium diffusion

    International Nuclear Information System (INIS)

    Paulin, R.

    1969-04-01

    The existence of two slow components in life-time spectrum of positron annihilation in silicium, aluminium and alkaline-earth oxides powders is established. These two long mean-lives ≅ 10 -9 s and ≅ 10 -7 s result from annihilation, inside and outside the grains respectively, of ortho-positronium formed in defects present in ionic crystals investigated. Dynamic behaviour of Ps, so revealed, is analyzed in terms of diffusion in excellent agreement with experiment. Diffusion constants of the order of 10 -4 cm 2 sec -1 and mean path before annihilation from 50 to 300 Angstrom are measured. From 100 to 500 K the temperature influence upon diffusion process is effective only in SiO 2 where activation energy is found about 10 -2 eV. The p-Ps zero point energy evaluated by angular correlation gives the order of magnitude for defects dimensions and diffusion mean-time. Finally, o-Ps behaviour in space between grains, where its interaction with atmospheric gases can be only detected, is analysed. (author) [fr

  16. Jovian atmospheres

    International Nuclear Information System (INIS)

    Allison, M.; Travis, L.D.

    1986-10-01

    A conference on the atmosphere of Jupiter produced papers in the areas of thermal and ortho-para hydrogen structure, clouds and chemistry, atmospheric structure, global dynamics, synoptic features and processes, atmospheric dynamics, and future spaceflight opportunities. A session on the atmospheres of Uranus and Neptune was included, and the atmosphere of Saturn was discussed in several papers

  17. Cesium diffusion in graphite

    International Nuclear Information System (INIS)

    Evans, R.B. III; Davis, W. Jr.; Sutton, A.L. Jr.

    1980-05-01

    Experiments on diffusion of 137 Cs in five types of graphite were performed. The document provides a completion of the report that was started and includes a presentation of all of the diffusion data, previously unpublished. Except for data on mass transfer of 137 Cs in the Hawker-Siddeley graphite, analyses of experimental results were initiated but not completed. The mass transfer process of cesium in HS-1-1 graphite at 600 to 1000 0 C in a helium atmosphere is essentially pure diffusion wherein values of (E/epsilon) and ΔE of the equation D/epsilon = (D/epsilon) 0 exp [-ΔE/RT] are about 4 x 10 -2 cm 2 /s and 30 kcal/mole, respectively

  18. Physical bases of the generation of short-term earthquake precursors: A complex model of ionization-induced geophysical processes in the lithosphere-atmosphere-ionosphere-magnetosphere system

    Science.gov (United States)

    Pulinets, S. A.; Ouzounov, D. P.; Karelin, A. V.; Davidenko, D. V.

    2015-07-01

    This paper describes the current understanding of the interaction between geospheres from a complex set of physical and chemical processes under the influence of ionization. The sources of ionization involve the Earth's natural radioactivity and its intensification before earthquakes in seismically active regions, anthropogenic radioactivity caused by nuclear weapon testing and accidents in nuclear power plants and radioactive waste storage, the impact of galactic and solar cosmic rays, and active geophysical experiments using artificial ionization equipment. This approach treats the environment as an open complex system with dissipation, where inherent processes can be considered in the framework of the synergistic approach. We demonstrate the synergy between the evolution of thermal and electromagnetic anomalies in the Earth's atmosphere, ionosphere, and magnetosphere. This makes it possible to determine the direction of the interaction process, which is especially important in applications related to short-term earthquake prediction. That is why the emphasis in this study is on the processes proceeding the final stage of earthquake preparation; the effects of other ionization sources are used to demonstrate that the model is versatile and broadly applicable in geophysics.

  19. Contribution to the study of diffusion as related to the leaching of glasses: application to the potential risk of long-term storage

    International Nuclear Information System (INIS)

    Imbert, J.C.; Pacaud, F.

    Leaching of glasses made from radioactive wastes of very high activity was studied. Leaching agents used were water for temperatures below 100 0 C; molten nitrates for temperatures higher than 100 0 C; solutions of various pH or charged with either sodium chloride or cesium; and dry or wet air. From the quantities of entrained radioactive elements, overall apparent diffusion coefficients were determined for fission products with long periods such as cerium, cesium, ruthenium, and strontium. Diffusion activation energies were also determined. These results are applied to the calculation of the potential risk of storage for vitrified fission products

  20. Standardized models for atmospheric diffusion applied to an highly industrialized area (Taranto, Italy): results, comparisons and future trends; Applicazione di modelli standardizzati di diffusione atmosferica all`area ad elevata concentrazione industriale di Taranto: confronti e linee di sviluppo

    Energy Technology Data Exchange (ETDEWEB)

    Brofferio, C.; Racalbuto, S. [ENEA, Centro Ricerche Casaccia, Rome (Italy). Dip. Ambiente; Desiato, F. [ANPA, Rome (Italy); Del Buono, P.

    1998-12-31

    In this paper the authors present and discuss the results obtained running the DIMULA code (DIffusion MULtisources in Atmosphere), the model has been applied to the industrial area of Taranto (Puglia, Italy), characterized by a large number of air emission sources of SO{sub 2} NOx, PST. Due to the lack of controlled data on emission and air concentrations outputs, the DIMULA code outputs were compared with those obtained from others dispersion models such as CDM (Climatological Dispersion Model) by EPA and AMETISTA (Air Quality based on MEteorological TIme Series and Turbolence Analysis) by ANPA. The air concentration values estimated by the three models are similar comparing the order of magnitude; only under specific meteo conditions (such as wind calm conditions) and near the emission sources, the three models lead to different results. [Italiano] Nel presente lavoro sono presentati e discussi i risultati ottenuti applicando il codice DIMULA (DIffusione MULtisorgente Atmosferica) dell`ENEA all`area industriale di Taranto (Puglia), caratterizzata da un elevato numero di sorgenti emissive in aria di SO{sub 2} NOx, PST. In mancanza di dati controllati di emissione e di concentrazione che fornissero indicazioni sulla validita` dei valori ottenuti, le valutazioni del DIMULA sono state confrontate con quelle fornite da altri modelli quali il CDM (Climatological Dispersion Model) dell`EPA e l`AMETISTA (Air Quality based on MEteorological TIme Series and Turbolence Analysis) dell`ANPA. Lo studio ha mostrato che le stime dei valori di concentrazione ottenute con i tre modelli sono in generale simili in ordine di grandezza tranne che in prossimita` delle sorgenti e in particolari condizioni meteorologiche quali la calma di vento.

  1. Two-dimensional temperature and carbon dioxide concentration profiles in atmospheric laminar diffusion flames measured by mid-infrared direct absorption spectroscopy at 4.2 μm

    Science.gov (United States)

    Liu, Xunchen; Zhang, Guoyong; Huang, Yan; Wang, Yizun; Qi, Fei

    2018-04-01

    We present a multi-line flame thermometry technique based on mid-infrared direct absorption spectroscopy of carbon dioxide at its v_3 fundamental around 4.2 μm that is particularly suitable for sooting flames. Temperature and concentration profiles of gas phase molecules in a flame are important characteristics to understand its flame structure and combustion chemistry. One of the standard laboratory flames to analyze polycyclic aromatic hydrocarbons (PAH) and soot formation is laminar non-premixed co-flow flame, but PAH and soot introduce artifact to most non-contact optical measurements. Here we report an accurate diagnostic method of the temperature and concentration profiles of CO2 in ethylene diffusion flames by measuring its v_3 vibrational fundamental. An interband cascade laser was used to probe the R-branch bandhead at 4.2 μm, which is highly sensitive to temperature change, free from soot interference and ambient background. Calibration measurement was carried out both in a low-pressure Herriott cell and an atmospheric pressure tube furnace up to 1550 K to obtain spectroscopic parameters for high-temperature spectra. In our co-flow flame measurement, two-dimensional line-of-sight optical depth of an ethylene/N2 laminar sooting flame was recorded by dual-beam absorption scheme. The axially symmetrical attenuation coefficient profile of CO2 in the co-flow flame was reconstructed from the optical depth by Abel inversion. Spatially resolved flame temperature and in situ CO2 volume fraction profiles were derived from the calibrated CO2 spectroscopic parameters and compared with temperature profiles measured by two-line atomic fluorescence.

  2. Diffusion effects in undulator radiation

    Directory of Open Access Journals (Sweden)

    Ilya Agapov

    2014-11-01

    Full Text Available Quantum diffusion effects in undulator radiation in semiclassical approximation are considered. Short-term effects on the electron beam motion are discussed and it is shown that approaches based on diffusion approximation with drift-diffusion coefficients derived from undulator or bending magnet radiation spectrum, and on Poisson statistics with radiation spectrum defined by the local beding field, all lead to similar results in terms of electron energy spread for cases of practical interest. An analytical estimate of the influence of quantum diffusion on the undulator radiation spectrum is derived.

  3. Development of More Cost-Effective Methods for Long-Term Monitoring of Soil Vapor Intrusion to Indoor Air Using Quantitative Passive Diffusive-Adsorptive Sampling Techniques

    Science.gov (United States)

    2015-05-01

    ASTM ASTM International ASU Arizona State University ATD automated thermal desorption BENZ Benzene C/Co passive sampler concentration...Protection Agency [USEPA], 1998a, b; California Department of Toxic Substance Control, 2011; ASTM International [ASTM] D7758, 2011). This demonstration... microporous sintered polyethylene, through which the vapors diffuse. Figure 1b. Radiello sampler with regular (white) and low-uptake rate

  4. Diffusion of Wilson loops

    International Nuclear Information System (INIS)

    Brzoska, A.M.; Lenz, F.; Thies, M.; Negele, J.W.

    2005-01-01

    A phenomenological analysis of the distribution of Wilson loops in SU(2) Yang-Mills theory is presented in which Wilson loop distributions are described as the result of a diffusion process on the group manifold. It is shown that, in the absence of forces, diffusion implies Casimir scaling and, conversely, exact Casimir scaling implies free diffusion. Screening processes occur if diffusion takes place in a potential. The crucial distinction between screening of fundamental and adjoint loops is formulated as a symmetry property related to the center symmetry of the underlying gauge theory. The results are expressed in terms of an effective Wilson loop action and compared with various limits of SU(2) Yang-Mills theory

  5. Atmospheric contamination

    International Nuclear Information System (INIS)

    Gruetter, Juerg

    1997-01-01

    It is about the levels of contamination in center America, the population's perception on the problem, effects of the atmospheric contamination, effects in the environment, causes of the atmospheric contamination, possibilities to reduce the atmospheric contamination and list of Roeco Swisscontac in atmospheric contamination

  6. 3-year follow-up of a long-term registry-based multicentre study on vitamin E diffused polyethylene in total hip replacement

    DEFF Research Database (Denmark)

    Sillesen, Nanna Hylleholt; Greene, Meridith E; Nebergall, Audrey K

    2016-01-01

    PURPOSE: Preclinical studies of vitamin E diffused highly cross-linked polyethylene (E-XLPE) has shown enhanced mechanical properties with less wear. The purpose of our study was to document the early clinical outcome of E-XLPE to ensure, for the safety of patients, that there are no unforeseen...... hip arthroplasty in functionality and quality of life across the centers. We have not observed any early in vivo adverse effects from diffusing the liners with vitamin E. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT00545285....... early adverse events from using this new biomaterial. METHODS: The enrolled patients (n = 977) have received either a porous titanium coated or porous plasma sprayed acetabular shell with either a E-XLPE liner or a medium cross-linked (AXL) liner. At each follow-up 5 patient-reported outcome measures...

  7. Daily Course of CO2 Fluxes in the Atmosphere-Water System and Variable Fluorescence of Phytoplankton during the Open-Water Period for Lake Baikal according to Long-Term Measurements

    Science.gov (United States)

    Zavoruev, V. V.; Domysheva, V. M.; Pestunov, D. A.; Sakirko, M. V.; Panchenko, M. V.

    2018-04-01

    The process of gas exchange of CO2 in the atmosphere-water system and its relation to the daily course of variable fluorescence of phytoplankton is studied on the basis of long-term (2004-2014) measurements during the open water period for Lake Baikal. It is found that the decrease in photosynthetic activity of plankton is almost synchronous to the increase in the CO2 flux from atmosphere to water. It follows from comparison of the spring and summer data with December measurements that the daily decrease in variable fluorescence of phytoplankton is caused by the internal daily rhythm of the photosynthetic activity of plankton.

  8. Assessment of liver tumor response by high-field (3 T) MRI after radiofrequency ablation: Short- and mid-term evolution of diffusion parameters within the ablation zone

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Tri-Linh, E-mail: tluonmac@gmail.com [Department of Diagnostic and Interventional Radiology, Centre Hospitalier Universitaire Vaudois, University of Lausanne, Rue du Bugnon 46, 1011 Lausanne (Switzerland); Becce, Fabio; Bize, Pierre; Denys, Alban; Meuli, Reto; Schmidt, Sabine [Department of Diagnostic and Interventional Radiology, Centre Hospitalier Universitaire Vaudois, University of Lausanne, Rue du Bugnon 46, 1011 Lausanne (Switzerland)

    2012-09-15

    Purpose: To compare the apparent diffusion coefficient (ADC) values of malignant liver lesions on diffusion-weighted MRI (DWI) before and after successful radiofrequency ablation (RF ablation). Materials and methods: Thirty-two patients with 43 malignant liver lesions (23/20: metastases/hepatocellular carcinomas (HCC)) underwent liver MRI (3.0 T) before (<1 month) and after RF ablation (at 1, 3 and 6 months) using T2-, gadolinium-enhanced T1- and DWI-weighted MR sequences. Jointly, two radiologists prospectively measured ADCs for each lesion by means of two different regions of interest (ROIs), first including the whole lesion and secondly the area with the visibly most restricted diffusion (MRDA) on ADC map. Changes of ADCs were evaluated with ANOVA and Dunnett tests. Results: Thirty-one patients were successfully treated, while one patient was excluded due to focal recurrence. In metastases (n = 22), the ADC in the whole lesion and in MRDA showed an up-and-down evolution. In HCC (n = 20), the evolution of ADC was more complex, but with significantly higher values (p = 0.013) at 1 and 6 months after RF ablation. Conclusion: The ADC values of malignant liver lesions successfully treated by RF ablation show a predictable evolution and may help radiologists to monitor tumor response after treatment.

  9. Nonlinear Cross-Diffusion with Size Exclusion

    KAUST Repository

    Burger, Martin; Di Francesco, Marco; Pietschmann, Jan-Frederik; Schlake, Bä rbel

    2010-01-01

    The aim of this paper is to investigate the mathematical properties of a continuum model for diffusion of multiple species incorporating size exclusion effects. The system for two species leads to nonlinear cross-diffusion terms with double

  10. Turing instability in reaction-diffusion systems with nonlinear diffusion

    Energy Technology Data Exchange (ETDEWEB)

    Zemskov, E. P., E-mail: zemskov@ccas.ru [Russian Academy of Sciences, Dorodnicyn Computing Center (Russian Federation)

    2013-10-15

    The Turing instability is studied in two-component reaction-diffusion systems with nonlinear diffusion terms, and the regions in parametric space where Turing patterns can form are determined. The boundaries between super- and subcritical bifurcations are found. Calculations are performed for one-dimensional brusselator and oregonator models.

  11. Reference Atmosphere for Mercury

    Science.gov (United States)

    Killen, Rosemary M.

    2002-01-01

    We propose that Ar-40 measured in the lunar atmosphere and that in Mercury's atmosphere is due to current diffusion into connected pore space within the crust. Higher temperatures at Mercury, along with more rapid loss from the atmosphere will lead to a smaller column abundance of argon at Mercury than at the Moon, given the same crustal abundance of potassium. Because the noble gas abundance in the Hermean atmosphere represents current effusion, it is a direct measure of the crustal potassium abundance. Ar-40 in the atmospheres of the planets is a measure of potassium abundance in the interiors, since Ar-40 is a product of radiogenic decay of K-40 by electron capture with the subsequent emission of a 1.46 eV gamma-ray. Although the Ar-40 in the Earth's atmosphere is expected to have accumulated since the late bombardment, Ar-40 in the atmospheres of Mercury and the Moon is eroded quickly by photoionization and electron impact ionization. Thus, the argon content in the exospheres of the Moon and Mercury is representative of current effusion rather than accumulation over the lifetime of the planet.

  12. Insights from a network of long-term measurements of biosphere-atmospheric exchanges of water vapor and carbon dioxide in southern Arizona

    Science.gov (United States)

    Scott, R. L.; Barron-Gafford, G.; Biederman, J. A.

    2016-12-01

    Around one-third of Earth's land surface is classified as semiarid, and carbon dioxide exchange in these regions has been shown to be an important regulator of both the trend and interannual variability of the terrestrial carbon sink. Fifteen years ago, when we began making measurements of biosphere-atmospheric exchanges of energy, water vapor, and carbon dioxide using eddy covariance in southern Arizona USA, there was paucity of semiarid observations in flux networks like Ameriflux. We started by establishing riparian sites across a woody plant encroachment gradient to quantify the productivity and consumptive plant water use along a iconic and ecologically important desert river. Soon thereafter, we added semiarid grassland, shrubland, and savanna sites that do not have access to groundwater in order to better understand how water limitation and changes in vegetation structure affect ecosystem productivity. Here, we highlight the value of multiyear, multisite flux data for addressing regional to global scale problems associated with groundwater pumping, land cover change, drought, and climate change. For the riparian sites, we find that ecosystem water availability is altered by vegetation structure such that ecosystems with more deeply rooted trees have higher productivity but at a cost of greater groundwater use. For the non-riparian sites, precipitation strongly controls ecosystem water availability and the resultant productivity, but differences in ecosystem structure impact water use efficiency due to the partitioning of evapotranspiration into its component sources. Also, the productivity at sites with more grass, and less woody, plants responds more quickly to precipitation fluctuations including long-term drought conditions. In semiarid regions, variability in water and carbon fluxes is much larger than in more mesic climes. Across our riparian and non-riparian sites, access to more stable groundwater reserves reduces variability in water and carbon

  13. Insights from a network of long-term measurements of biosphere-atmospheric exchanges of water vapor and carbon dioxide in a water-limited semiarid region

    Science.gov (United States)

    Scott, Russell; Biederman, Joel

    2017-04-01

    Around one-third of Earth's land surface is classified as semiarid, and carbon dioxide exchange in these regions has been shown to be an important regulator of both the trend and interannual variability of the terrestrial carbon sink. Fifteen years ago, when we began making measurements of biosphere-atmospheric exchanges of energy, water vapor, and carbon dioxide using eddy covariance in southern Arizona USA, there was paucity of semiarid observations in flux networks like AmeriFlux and EuroFlux. We started by establishing riparian sites across a woody plant encroachment gradient to quantify the productivity and consumptive plant water use along a iconic and ecologically important desert river. Soon thereafter, we added semiarid grassland, shrubland, and savanna sites that do not have access to groundwater in order to better understand how water limitation and changes in vegetation structure affect ecosystem productivity. Here, we highlight the value of multiyear, multisite flux data for addressing regional to global scale problems associated with groundwater pumping, land cover change, drought, and climate change. For the riparian sites, we find that ecosystem water availability is altered by vegetation structure such that ecosystems with more deeply rooted trees have higher productivity but at a cost of greater groundwater use. For the non-riparian sites, precipitation strongly controls ecosystem water availability and the resultant productivity, but differences in ecosystem structure impact water use efficiency due to the partitioning of evapotranspiration into its component sources. Also, the productivity at sites with more grass, and less woody, plants responds more quickly to precipitation fluctuations including long-term drought conditions. In semiarid regions, variability in water and carbon fluxes is much larger than in more mesic climes. Across our riparian and non-riparian sites, access to more stable groundwater reserves reduces variability in water and

  14. Spatial Mapping of Translational Diffusion Coefficients Using Diffusion Tensor Imaging: A Mathematical Description.

    Science.gov (United States)

    Shetty, Anil N; Chiang, Sharon; Maletic-Savatic, Mirjana; Kasprian, Gregor; Vannucci, Marina; Lee, Wesley

    2014-01-01

    In this article, we discuss the theoretical background for diffusion weighted imaging and diffusion tensor imaging. Molecular diffusion is a random process involving thermal Brownian motion. In biological tissues, the underlying microstructures restrict the diffusion of water molecules, making diffusion directionally dependent. Water diffusion in tissue is mathematically characterized by the diffusion tensor, the elements of which contain information about the magnitude and direction of diffusion and is a function of the coordinate system. Thus, it is possible to generate contrast in tissue based primarily on diffusion effects. Expressing diffusion in terms of the measured diffusion coefficient (eigenvalue) in any one direction can lead to errors. Nowhere is this more evident than in white matter, due to the preferential orientation of myelin fibers. The directional dependency is removed by diagonalization of the diffusion tensor, which then yields a set of three eigenvalues and eigenvectors, representing the magnitude and direction of the three orthogonal axes of the diffusion ellipsoid, respectively. For example, the eigenvalue corresponding to the eigenvector along the long axis of the fiber corresponds qualitatively to diffusion with least restriction. Determination of the principal values of the diffusion tensor and various anisotropic indices provides structural information. We review the use of diffusion measurements using the modified Stejskal-Tanner diffusion equation. The anisotropy is analyzed by decomposing the diffusion tensor based on symmetrical properties describing the geometry of diffusion tensor. We further describe diffusion tensor properties in visualizing fiber tract organization of the human brain.

  15. Fractional Diffusion Equations and Anomalous Diffusion

    Science.gov (United States)

    Evangelista, Luiz Roberto; Kaminski Lenzi, Ervin

    2018-01-01

    Preface; 1. Mathematical preliminaries; 2. A survey of the fractional calculus; 3. From normal to anomalous diffusion; 4. Fractional diffusion equations: elementary applications; 5. Fractional diffusion equations: surface effects; 6. Fractional nonlinear diffusion equation; 7. Anomalous diffusion: anisotropic case; 8. Fractional Schrödinger equations; 9. Anomalous diffusion and impedance spectroscopy; 10. The Poisson–Nernst–Planck anomalous (PNPA) models; References; Index.

  16. Relating landfill gas emissions to atmospheric pressure using numerical modeling and state-space analysis

    DEFF Research Database (Denmark)

    Poulsen, T.G.; Christophersen, Mette; Moldrup, P.

    2003-01-01

    were applied: (I) State-space analysis was used to identify relations between gas flux and short-term (hourly) variations in atmospheric pressure. (II) A numerical gas transport model was fitted to the data and used to quantify short-term impacts of variations in atmospheric pressure, volumetric soil......-water content, soil gas permeability, soil gas diffusion coefficients, and biological CH4 degradation rate upon landfill gas concentration and fluxes in the soil. Fluxes and concentrations were found to be most sensitive to variations in volumetric soil water content, atmospheric pressure variations and gas...... permeability whereas variations in CH4 oxidation rate and molecular coefficients had less influence. Fluxes appeared to be most sensitive to atmospheric pressure at intermediate distances from the landfill edge. Also overall CH4 fluxes out of the soil over longer periods (years) were largest during periods...

  17. Real-time computing of the environmental consequences of an atmospheric accidental release of radioactive material: user's point of view

    International Nuclear Information System (INIS)

    Boeri, G.; Caracciolo, R.; Dickerson, M.

    1985-07-01

    All calculations of the consequences of an atmospheric release must start with atmospheric dispersion calculations. Time factors make external and inhalation dose estimates of immediate concern closely followed by ground contamination of land, pastures and onch agricultural crops. In general, the difficulties in modeling the source term and atmospheric transport and diffusion account for most of the error in calculating the dose to man. Thus, sophisticated treatment of the dose part of the calculating is not usually justified, though the relative distribution of dose in individual organs may be needed for correct decision marking. This paper emphasizes the atmospheric transport and diffusion part of the dose estimate and relates how this calculation can be used to estimate dose. 12 refs

  18. Phenomenology of atmospheric neutrinos

    Directory of Open Access Journals (Sweden)

    Fedynitch Anatoli

    2016-01-01

    Full Text Available The detection of astrophysical neutrinos, certainly a break-through result, introduced new experimental challenges and fundamental questions about acceleration mechanisms of cosmic rays. On one hand IceCube succeeded in finding an unambiguous proof for the existence of a diffuse astrophysical neutrino flux, on the other hand the precise determination of its spectral index and normalization requires a better knowledge about the atmospheric background at hundreds of TeV and PeV energies. Atmospheric neutrinos in this energy range originate mostly from decays of heavy-flavor mesons, which production in the phase space relevant for prompt leptons is uncertain. Current accelerator-based experiments are limited by detector acceptance and not so much by the collision energy. This paper recaps phenomenological aspects of atmospheric leptons and calculation methods, linking recent progress in flux predictions with particle physics at colliders, in particular the Large Hadron Collider.

  19. Atmosphere and Ambient Space

    DEFF Research Database (Denmark)

    Schmidt, Ulrik

    Atmosphere and Ambient Space This paper explores the relation between atmosphere and ambient space. Atmosphere and ambient space share many salient properties. They are both ontologically indeterminate, constantly varying and formally diffuse and they are both experienced as a subtle, non......-signifying property of a given space. But from a certain point of view, the two concepts also designate quite dissimilar experiences of space. To be ’ambient’ means to surround. Accordingly, ambient space is that space, which surrounds something or somebody. (Gibson 1987: 65) Since space is essentially...... of a surrounding character, all space can thus be described as having a fundamentally ambient character. So what precisely is an ambient space, then? As I will argue in my presentation, ambient space is a sensory effect of spatiality when a space is experienced as being particularly surrounding: a ‘space effect...

  20. Diffuse sound field: challenges and misconceptions

    DEFF Research Database (Denmark)

    Jeong, Cheol-Ho

    2016-01-01

    Diffuse sound field is a popular, yet widely misused concept. Although its definition is relatively well established, acousticians use this term for different meanings. The diffuse sound field is defined by a uniform sound pressure distribution (spatial diffusion or homogeneity) and uniform...... tremendously in different chambers because the chambers are non-diffuse in variously different ways. Therefore, good objective measures that can quantify the degree of diffusion and potentially indicate how to fix such problems in reverberation chambers are needed. Acousticians often blend the concept...... of mixing and diffuse sound field. Acousticians often refer diffuse reflections from surfaces to diffuseness in rooms, and vice versa. Subjective aspects of diffuseness have not been much investigated. Finally, ways to realize a diffuse sound field in a finite space are discussed....

  1. Climatology of transport and diffusion conditions along the United States Atlantic and Gulf coasts

    International Nuclear Information System (INIS)

    Raynor, G.S.; Hayes, J.V.

    1981-01-01

    A study of the atmospheric transport and diffusion climatology of the United States east and Gulf coasts was conducted to aid in planning and site selection for potentially polluting installations. This paper presents selected results from an extensive statistical study. Regular hourly observational data were obtained from 30 coastal stations from Maine to Texas and analyzed in terms of conditions important to emission transport and diffusion. The 30 stations included four pairs with one of each pair at a greater distance from the coast than the other but near the same latitude

  2. Short-term exposure to atmospheric ammonia does not affect frost hardening of needles from three- and five-year-old Scots pine trees

    NARCIS (Netherlands)

    Clement, J.M A M; van Hasselt, P.R; van Eerden, L.J.M.; Dueck, T.A.

    The effect of atmospheric ammonia on frost hardening of needles from 3- and 5-year-old Scots pine trees was investigated. Trees were exposed to various concentrations of NH(3) during different hardening stages under laboratory conditions and in experiments with open-top chambers under a natural

  3. Soil respiration, root biomass, and root turnover following long-term exposure of northern forests to elevated atmospheric CO2 and tropospheric O3

    Science.gov (United States)

    Kurt S. Pregitzer; Andrew J. Burton; John S. King; Donald R. Zak

    2008-01-01

    The Rhinelander free-air CO2 enrichment (FACE) experiment is designed to understand ecosystem response to elevated atmospheric carbon dioxide (+CO2) and elevated tropospheric ozone (+O3). The objectives of this study were: to understand how soil respiration responded to the experimental treatments; to...

  4. Long-term variations of 14C and 137Cs in the Bratislava air – implications of different atmospheric transport processes

    International Nuclear Information System (INIS)

    Povinec, P.P.; Holý, K.; Chudý, M.; Šivo, A.; Sýkora, I.; Ješkovský, M.; Richtáriková, M.

    2012-01-01

    This study summarizes measurements of atmospheric 14 C and 137 Cs in the Bratislava air since 1976. Higher 14 C levels observed in spring and early summer months until the 1980’s confirm injection of the stratospheric air into the troposphere. Later, deep winter minima were observed in 14 C concentrations, probably due to the depletion of the atmospheric 14 C levels in winter months by the injection of large quantities of fossil CO 2 . Presently observed 14 C maxima in summer and minima in winter were caused by the depletion of the atmospheric 14 C in winter months, amplified by temperature inversions during winter, rather than by the injection of the stratospheric air into the troposphere. The observed 137 Cs activity concentrations also showed an impact of the stratospheric air on the 137 Cs levels until the early 1980’s, documented by typical spring/early summer maxima and winter minima. The global fallout 137 Cs record was then disturbed by the Chernobyl accident (1986) when large quantities of 137 Cs were released to the atmosphere. The recent 137 Cs variations observed in the atmosphere, characterised by winter maxima and summer minima, are assumed to be mainly due to the resuspension of 137 Cs from the soil. A correlation was found between the 137 Cs activity concentration and the dust level in the air (the correlation coefficient r = 0.74), as well as an anticorrelation with the temperature (r = −0.56). - Highlights: ► The recent 14 C variations in the Bratislava air were caused by the depletion of the atmospheric 14 C levels in winter months due to inputs of fossil CO 2 into the atmosphere. ► The recent 137 Cs variations observed in the Bratislava air were mainly due to the resuspension of 137 Cs from the soil. ► The 137 Cs activity concentration correlated with the dust level in the air (the correlation coefficient r = 0.74), and anticorrelated with the temperature (r = −0.56).

  5. Radionuclide dispersion in the atmosphere

    International Nuclear Information System (INIS)

    Moura Neto, C. de; Amorim, E.S. do; Panetta, J.

    1979-05-01

    The instantaneous liberation of radionuclides in the atmosphere is studied in three dimensions, according to the formalism of the diffusion theory. The analytical solution, expose to gravitational and an atmospherical effects, is combined with the discretization of space and time in the calculation of levels of exposure. A typical inventory (for a PWR) was considered in the calculation of immersion doses, and the results permitted a comparative analysis among the different existing models. (Author) [pt

  6. TU-F-CAMPUS-I-01: Head and Neck Squamous Cell Carcinoma: Short-Term Repeatability of Apparent Diffusion Coefficient and Intravoxel Incoherent Motion Parameters at 3.0T

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Y; Fuller, C; Mohamed, A; Wang, J; Hazle, J [UT MD Anderson Cancer Center, Houston, TX (United States)

    2015-06-15

    Purpose: Many published studies have recently demonstrated the potential value of intravoxel incoherent motion (IVIM) analysis for disease evaluation. However, few have questioned its measurement repeatability/reproducibility when applied. The purpose of this study was to determine the short-term measurement repeatability of apparent diffusion coefficient ADC, true diffusion coefficient D, pseudodiffusion coefficient D* and perfusion fraction f, in head and neck squamous cell carcinoma (HNSCC) primary tumors and metastatic nodes. Methods: Ten patients with known HNSCC were examined twice using echo-planar DW-MRI with 12 b values (0 to 800 s/mm2) 1hour to 24 hours apart before radiation treatment. All patients were scanned with the customized radiation treatment immobilization devices to reduce motion artifacts and to improve image registration in repeat scans. Regions of interests were drawn in primary tumor and metastases node in each patient (Fig. 1). ADC and IVIM parameters D, D* and f were calculated by least squares data fitting. Short-term test–retest repeatability of ADC and IVIM parameters were assessed by measuring Bland–Altman limits of agreements (BA-LA). Results: Sixteen HNSCC lesions were assessed in 10 patients. Repeatability of perfusion-sensitive parameters, D* and f, in HNSCC lesions was poor (BA-LA: -144% to 88% and −57% to 96% for D* and f, respectively); a lesser extent was observed for the diffusion-sensitive parameters of ADC and D (BA-LA: −34% to 39% and −37% to 40%, for ADC and D, respectively) (Fig. 2). Conclusion: Poor repeatability of D*/f and good repeatability for ADC/D were observed in HNSCC primary tumors and metastatic nodes. Efforts should be made to improve the measurement repeatability of perfusion-sensitive IVIM parameters.

  7. Eddy diffusion coefficients and their upper limits based on application of the similarity theory

    Directory of Open Access Journals (Sweden)

    M. N. Vlasov

    2015-07-01

    Full Text Available The equation for the diffusion velocity in the mesosphere and the lower thermosphere (MLT includes the terms for molecular and eddy diffusion. These terms are very similar. For the first time, we show that, by using the similarity theory, the same formula can be obtained for the eddy diffusion coefficient as the commonly used formula derived by Weinstock (1981. The latter was obtained by taking, as a basis, the integral function for diffusion derived by Taylor (1921 and the three-dimensional Kolmogorov kinetic energy spectrum. The exact identity of both formulas means that the eddy diffusion and heat transport coefficients used in the equations, both for diffusion and thermal conductivity, must meet a criterion that restricts the outer eddy scale to being much less than the scale height of the atmosphere. This requirement is the same as the requirement that the free path of molecules must be much smaller than the scale height of the atmosphere. A further result of this criterion is that the eddy diffusion coefficients Ked, inferred from measurements of energy dissipation rates, cannot exceed the maximum value of 3.2 × 106 cm2 s−1 for the maximum value of the energy dissipation rate of 2 W kg−1 measured in the mesosphere and the lower thermosphere (MLT. This means that eddy diffusion coefficients larger than the maximum value correspond to eddies with outer scales so large that it is impossible to use these coefficients in eddy diffusion and eddy heat transport equations. The application of this criterion to the different experimental data shows that some reported eddy diffusion coefficients do not meet this criterion. For example, the large values of these coefficients (1 × 107 cm2 s−1 estimated in the Turbulent Oxygen Mixing Experiment (TOMEX do not correspond to this criterion. The Ked values inferred at high latitudes by Lübken (1997 meet this criterion for summer and winter polar data, but the Ked values for summer at low latitudes

  8. Amplitude equations for a sub-diffusive reaction-diffusion system

    International Nuclear Information System (INIS)

    Nec, Y; Nepomnyashchy, A A

    2008-01-01

    A sub-diffusive reaction-diffusion system with a positive definite memory operator and a nonlinear reaction term is analysed. Amplitude equations (Ginzburg-Landau type) are derived for short wave (Turing) and long wave (Hopf) bifurcation points

  9. Global atmospheric changes.

    OpenAIRE

    Piver, W T

    1991-01-01

    Increasing concentrations of CO2 and other greenhouse gases in the atmosphere can be directly related to global warming. In terms of human health, because a major cause of increasing atmospheric concentrations of CO2 is the increased combustion of fossil fuels, global warming also may result in increases in air pollutants, acid deposition, and exposure to ultraviolet (UV) radiation. To understand better the impacts of global warming phenomena on human health, this review emphasizes the proces...

  10. Effects of Long-Term CO2 Enrichment on Soil-Atmosphere CH4 Fluxes and the Spatial Micro-Distribution of Methanotrophic Bacteria.

    Science.gov (United States)

    Karbin, Saeed; Guillet, Cécile; Kammann, Claudia I; Niklaus, Pascal A

    2015-01-01

    Effects of elevated atmospheric CO2 concentrations on plant growth and associated C cycling have intensively been studied, but less is known about effects on the fluxes of radiatively active trace gases other than CO2. Net soil-atmosphere CH4 fluxes are determined by the balance of soil microbially-driven methane (CH4) oxidation and methanogenesis, and both might change under elevated CO2. Here, we studied CH4 dynamics in a permanent grassland exposed to elevated CO2 for 14 years. Soil-atmosphere fluxes of CH4 were measured using large static chambers, over a period of four years. The ecosystem was a net sink for atmospheric CH4 for most of the time except summer to fall when net CH4 emissions occurred. We did not detect any elevated CO2 effects on CH4 fluxes, but emissions were difficult to quantify due to their discontinuous nature, most likely because of ebullition from the saturated zone. Potential methanotrophic activity, determined by incubation of fresh sieved soil under standardized conditions, also did not reveal any effect of the CO2 treatment. Finally, we determined the spatial micro-distribution of methanotrophic activity at less than 5× atmospheric (10 ppm) and elevated (10000 ppm) CH4 concentrations, using a novel auto-radiographic technique. These analyses indicated that domains of net CH4 assimilation were distributed throughout the analyzed top 15 cm of soils, with no dependence on CH4 concentration or CO2 treatment. Our investigations suggest that elevated CO2 exerts no or only minor effects on CH4 fluxes in the type of ecosystem we studied, at least as long as soil moisture differences are small or absent as was the case here. The autoradiographic analyses further indicate that the spatial niche of CH4 oxidation does not shift in response to CO2 enrichment or CH4 concentration, and that the same type of methanotrophs may oxidize CH4 from atmospheric and soil-internal sources.

  11. Long-term trends in the middle atmosphere dynamics at northern middle latitudes – one regime or two different regimes?

    Czech Academy of Sciences Publication Activity Database

    Laštovička, Jan; Križan, Peter; Kozubek, Michal

    2010-01-01

    Roč. 10, č. 2 (2010), s. 2633-2668 ISSN 1680-7367 R&D Projects: GA ČR(CZ) GC205/07/J052 Institutional research plan: CEZ:AV0Z30420517 Keywords : greenhouse gases * ozone layer * stratosphere * ionospheric electron density * middle atmosphere * ionosphere Subject RIV: DG - Athmosphere Sciences, Meteorology http://www.atmos-chem-phys-discuss.net/10/2633/2010/acpd-10-2633-2010.pdf

  12. Pluto's atmosphere

    International Nuclear Information System (INIS)

    Elliot, J.L.; Dunham, E.W.; Bosh, A.S.; Slivan, S.M.; Young, L.A.

    1989-01-01

    Airborne CCD photometer observations of Pluto's June 9, 1988 stellar occultation have yielded an occultation lightcurve, probing two regions on the sunrise limb 2000 km apart, which reveals an upper atmosphere overlying an extinction layer with an abrupt upper boundary. The extinction layer may surround the entire planet. Attention is given to a model atmosphere whose occultation lightcurve closely duplicates observations; fits of the model to the immersion and emersion lightcurves exhibit no significant derived atmosphere-structure differences. Assuming a pure methane atmosphere, surface pressures of the order of 3 microbars are consistent with the occultation data. 43 references

  13. Atmospheric electricity

    CERN Document Server

    Chalmers, J Alan

    1957-01-01

    Atmospheric Electricity brings together numerous studies on various aspects of atmospheric electricity. This book is composed of 13 chapters that cover the main problems in the field, including the maintenance of the negative charge on the earth and the origin of the charges in thunderstorms. After a brief overview of the historical developments of atmospheric electricity, this book goes on dealing with the general principles, results, methods, and the MKS system of the field. The succeeding chapters are devoted to some aspects of electricity in the atmosphere, such as the occurrence and d

  14. Short-term variability of 7Be atmospheric deposition and watershed response in a Pacific coastal stream, Monterey Bay, California, USA

    Science.gov (United States)

    Conaway, Christopher H.; Storlazzi, Curt D.; Draut, Amy E.; Swarzenski, Peter W.

    2013-01-01

    Beryllium-7 is a powerful and commonly used tracer for environmental processes such as watershed sediment provenance, soil erosion, fluvial and nearshore sediment cycling, and atmospheric fallout. However, few studies have quantified temporal or spatial variability of 7Be accumulation from atmospheric fallout, and parameters that would better define the uses and limitations of this geochemical tracer. We investigated the abundance and variability of 7Be in atmospheric deposition in both rain events and dry periods, and in stream surface-water samples collected over a ten-month interval at sites near northern Monterey Bay (37°N, 122°W) on the central California coast, a region characterized by a rainy winters, dry summers, and small mountainous streams with flashy hydrology. The range of 7Be activity in rainwater samples from the main sampling site was 1.3–4.4 Bq L−1, with a mean (±standard deviation) of 2.2 ± 0.9 Bq L−1, and a volume-weighted average of 2.0 Bq L−1. The range of wet atmospheric deposition was 18–188 Bq m−2 per rain event, with a mean of 72 ± 53 Bq m−2. Dry deposition fluxes of 7Be ranged from less than 0.01 up to 0.45 Bq m−2 d−1, with an estimated dry season deposition of 7 Bq m−2 month−1. Annualized 7Be atmospheric deposition was approximately 1900 Bq m−2 yr−1, with most deposition via rainwater (>95%) and little via dry deposition. Overall, these activities and deposition fluxes are similar to values found in other coastal locations with comparable latitude and Mediterranean-type climate. Particulate 7Be values in the surface water of the San Lorenzo River in Santa Cruz, California, ranged from −1 to 0.6 Bq g−1, with a median activity of 0.26 Bq g−1. A large storm event in January 2010 characterized by prolonged flooding resulted in the entrainment of 7Be-depleted sediment, presumably from substantial erosion in the watershed. There were too few particulate 7Be data over the storm to accurately model a 7Be load

  15. Modelling of the long-term fate of pesticide residues in agricultural soils and their surface exchange with the atmosphere: Part II. Projected long-term fate of pesticide residues.

    Science.gov (United States)

    Scholtz, M T; Bidleman, T F

    2007-05-01

    In the first part of this paper, a simple coupled dynamic soil-atmosphere model for studying the gaseous exchange of pesticide soil residues with the atmosphere is described and evaluated by comparing model results with published measurements of pesticide concentrations in air and soil. In Part II, the model is used to study the concentration profiles of pesticide residues in both undisturbed and annually tilled agricultural soils. Future trends are estimated for the measured air and soil concentrations of lindane and six highly persistent pesticides (toxaphene, p,p'-DDE, dieldrin, cis- and trans-chlordane and trans-nonachlor) over a twenty-year period due to volatilization and leaching into the deeper soil. Wet deposition and particle associated pesticide deposition (that increase soil residue concentrations) and soil erosion, degradation in the soil (other than for lindane) and run-off in precipitation are not considered in this study. Estimates of the rain deposition fluxes are reported that show that, other than for lindane, net volatilization fluxes greatly exceed rain deposition fluxes. The model shows that the persistent pesticides studied are highly immobile in soil and that loss of these highly persistent residues from the soil is by volatilization rather than leaching into the deeper soil. The soil residue levels of these six pesticides are currently sources of net volatilization to the atmosphere and will remain so for many years. The maximum rate of volatilization from the soil was simulated by setting the atmospheric background concentration to zero; these simulations show that the rates of volatilization will not be significantly increased since soil resistance rather than the atmospheric concentration controls the volatilization rates. Annual tilling of the soils increases the volatilization loss to the atmosphere. Nonetheless, the model predicts that, if only air-soil exchange is considered, more than 76% of current persistent pesticide residues

  16. Short-term variability of 7Be atmospheric deposition and watershed response in a Pacific coastal stream, Monterey Bay, California, USA

    International Nuclear Information System (INIS)

    Conaway, Christopher H.; Storlazzi, Curt D.; Draut, Amy E.; Swarzenski, Peter W.

    2013-01-01

    Beryllium-7 is a powerful and commonly used tracer for environmental processes such as watershed sediment provenance, soil erosion, fluvial and nearshore sediment cycling, and atmospheric fallout. However, few studies have quantified temporal or spatial variability of 7 Be accumulation from atmospheric fallout, and parameters that would better define the uses and limitations of this geochemical tracer. We investigated the abundance and variability of 7 Be in atmospheric deposition in both rain events and dry periods, and in stream surface-water samples collected over a ten-month interval at sites near northern Monterey Bay (37°N, 122°W) on the central California coast, a region characterized by a rainy winters, dry summers, and small mountainous streams with flashy hydrology. The range of 7 Be activity in rainwater samples from the main sampling site was 1.3–4.4 Bq L −1 , with a mean (±standard deviation) of 2.2 ± 0.9 Bq L −1 , and a volume-weighted average of 2.0 Bq L −1 . The range of wet atmospheric deposition was 18–188 Bq m −2 per rain event, with a mean of 72 ± 53 Bq m −2 . Dry deposition fluxes of 7 Be ranged from less than 0.01 up to 0.45 Bq m −2 d −1 , with an estimated dry season deposition of 7 Bq m −2 month −1 . Annualized 7 Be atmospheric deposition was approximately 1900 Bq m −2 yr −1 , with most deposition via rainwater (>95%) and little via dry deposition. Overall, these activities and deposition fluxes are similar to values found in other coastal locations with comparable latitude and Mediterranean-type climate. Particulate 7 Be values in the surface water of the San Lorenzo River in Santa Cruz, California, ranged from −1 to 0.6 Bq g −1 , with a median activity of 0.26 Bq g −1 . A large storm event in January 2010 characterized by prolonged flooding resulted in the entrainment of 7 Be-depleted sediment, presumably from substantial erosion in the watershed. There were too few particulate 7 Be data over the storm

  17. Multipassage diffuser

    International Nuclear Information System (INIS)

    Lalis, A.; Rouviere, R.; Simon, G.

    1976-01-01

    A multipassage diffuser having 2p passages comprises a leak-tight cylindrical enclosure closed by a top cover and a bottom end-wall, parallel porous tubes which are rigidly assembled in sectors between tube plates and through which the gas mixture flows, the tube sectors being disposed at uniform intervals on the periphery of the enclosure. The top tube plates are rigidly fixed to an annular header having the shape of a half-torus and adapted to communicate with the tubes of the corresponding sector. Each passage is constituted by a plurality of juxtaposed sectors in which the mixture circulates in the same direction, the header being divided into p portions limited by radial partition-walls and each constituting two adjacent passages. The diffuser is provided beneath the bottom end-wall with p-1 leak-tight chambers each adapted to open into two different portions of the header, and with two collector-chambers each fitted with a nozzle for introducing the gas mixture and discharging the fraction of the undiffused mixture. By means of a central orifice formed in the bottom end-wall the enclosure communicates with a shaft for discharging the diffused fraction of the gas mixture

  18. 大气水汽同位素组成的短期变异特征%Short-term variations of vapor isotope ratios reveal the influence of atmospheric processes

    Institute of Scientific and Technical Information of China (English)

    张世春; 孙晓敏; 王建林; 于贵瑞; 温学发

    2011-01-01

    Stable isotopes of atmospheric water vapor reveal rich information on water movement and phase changes in the atmosphere. Here we presented two nearly continuous time-series of δD and δ18O of atmospheric water vapor (δv) measured at hourly intervals in surface air in Beijing and above a winter wheat canopy in Shijiazhuang using in-situ measurement technique. During the precipitation events, the δv values in both Beijing and Shijiazhuang were in the state of equilibrium with precipitation water, revealing the influence of precipitation processes. However, the δv departures from the equilibrium state were positively correlated with local relative humidity. Note that the δv tended to enrich in Beijing, but deplete in Shijiazhuang during the precipitation events, which mainly resulted from the influence of transpiration processes that enriched the δv in Shijiazhuang. On seasonal time-scale, the δvvalues were log-linear functions of water vapor mixing ratios in both Beijing and Shijiazhuang. The water vapor mixing ratio was an excellent predictor of the δv by the Rayleigh distillation mechanisms, indicating that air mass advection could also play an important role in determining the δv. On a diurnal time-scale, the δv reached the minimum in the early afternoon hours in Beijing which was closely related to the atmospheric processes of boundary layer entrainment. During the peak of growing season of winter wheat, however, the δv reached the minimum in the early morning, and increased gradually through the daytime, and reached the maximum in the late afternoon, which was responsible by the interaction between boundary layer entrainment and the local atmospheric processes, such as transpiration and dew formation. This study has the implications for the important role of vegetation in determining the surface δv and highlights the need to conduct δv measurement on short-term (e.g. diurnal) time scales.

  19. Some Aspects of Diffusion Theory

    CERN Document Server

    Pignedoli, A

    2011-01-01

    This title includes: V.C.A. Ferraro: Diffusion of ions in a plasma with applications to the ionosphere; P.C. Kendall: On the diffusion in the atmosphere and ionosphere; F. Henin: Kinetic equations and Brownian motion; T. Kahan: Theorie des reacteurs nucleaires: methodes de resolution perturbationnelles, interactives et variationnelles; C. Cattaneo: Sulla conduzione del calore; C. Agostinelli: Formule di Green per la diffusione del campo magnetico in un fluido elettricamente conduttore; A. Pignedoli: Transformational methods applied to some one-dimensional problems concerning the equations of t

  20. Articulating Atmospheres

    DEFF Research Database (Denmark)

    Kinch, Sofie

    2011-01-01

    This paper presents an architectural approach to designing computational interfaces by articulating the notion of atmosphere in the field of interaction design. It draws upon the concept of kinesthetic interaction and a philosophical notion on atmosphere emphasizing the importance of bodily...

  1. Atmospheric electrodynamics

    International Nuclear Information System (INIS)

    Volland, H.

    1984-01-01

    The book Atmospheric Electrodynamics, by Hans Voland is reviewed. The book describes a wide variety of electrical phenomena occurring in the upper and lower atmosphere and develops the mathematical models which simulate these processes. The reviewer finds that the book is of interest to researchers with a background in electromagnetic theory but is of only limited use as a reference work

  2. Urban atmospheres.

    Science.gov (United States)

    Gandy, Matthew

    2017-07-01

    What is an urban atmosphere? How can we differentiate an 'atmosphere' from other facets of urban consciousness and experience? This essay explores some of the wider cultural, political, and philosophical connotations of atmospheres as a focal point for critical reflections on space and subjectivity. The idea of an 'affective atmosphere' as a distinctive kind of mood or shared corporeal phenomenon is considered in relation to recent developments in phenomenology, extended conceptions of agency, and new understandings of materialism. The essay draws in particular on the changing characteristics of air and light to reflect on different forms of sensory experience and their wider cultural and political connotations. The argument highlights some of the tensions and anomalies that permeate contemporary understandings of urban atmospheres.

  3. Numerical model simulation of atmospheric coolant plumes

    International Nuclear Information System (INIS)

    Gaillard, P.

    1980-01-01

    The effect of humid atmospheric coolants on the atmosphere is simulated by means of a three-dimensional numerical model. The atmosphere is defined by its natural vertical profiles of horizontal velocity, temperature, pressure and relative humidity. Effluent discharge is characterised by its vertical velocity and the temperature of air satured with water vapour. The subject of investigation is the area in the vicinity of the point of discharge, with due allowance for the wake effect of the tower and buildings and, where application, wind veer with altitude. The model equations express the conservation relationships for mometum, energy, total mass and water mass, for an incompressible fluid behaving in accordance with the Boussinesq assumptions. Condensation is represented by a simple thermodynamic model, and turbulent fluxes are simulated by introduction of turbulent viscosity and diffusivity data based on in-situ and experimental water model measurements. The three-dimensional problem expressed in terms of the primitive variables (u, v, w, p) is governed by an elliptic equation system which is solved numerically by application of an explicit time-marching algorithm in order to predict the steady-flow velocity distribution, temperature, water vapour concentration and the liquid-water concentration defining the visible plume. Windstill conditions are simulated by a program processing the elliptic equations in an axisymmetrical revolution coordinate system. The calculated visible plumes are compared with plumes observed on site with a view to validate the models [fr

  4. Long-term atmospheric wet deposition of dissolved organic nitrogen in a typical red-soil agro-ecosystem, Southeastern China.

    Science.gov (United States)

    Cui, Jian; Zhou, Jing; Peng, Ying; He, Yuan Q; Yang, Hao; Xu, Liang J; Chan, Andy

    2014-05-01

    Dissolved organic nitrogen (DON) from atmospheric deposition has been a growing concern in the world and atmospheric nitrogen (N) deposition is increasing quickly in China especially Southeastern China. In our study, DON wet deposition was estimated by collecting and analyzing rainwater samples continuously over eight years (2005-2012) in a typical red-soil farmland ecosystem, Southeast China. Results showed that the volume-weighted-average DON concentration varied from 0.2 to 3.3 mg N L(-1) with an average of 1.2 mg N L(-1). DON flux ranged from 5.7 to 71.6 kg N ha(-1) year(-1) and averaged 19.7 kg N ha(-1) year(-1) which accounted for 34.6% of the total dissolved nitrogen (TDN) in wet deposition during the eight-year period. Analysis of DON concentration and flux, contribution of DON to TDN, rainfall, rain frequency, air temperature and wind frequency and the application of pig manure revealed possible pollution sources. Significant positive linear relation of annual DON flux and usage of pig manure (Pcycle in the red-soil agro-ecosystem in the future.

  5. Building long-term and high spatio-temporal resolution precipitation and air temperature reanalyses by mixing local observations and global atmospheric reanalyses: the ANATEM model

    Directory of Open Access Journals (Sweden)

    A. Kuentz

    2015-06-01

    The ANATEM model has been also evaluated for the regional scale against independent long-term time series and was able to capture regional low-frequency variability over more than a century (1883–2010.

  6. Oxygen diffusion in zircon

    Science.gov (United States)

    Watson, E. B.; Cherniak, D. J.

    1997-05-01

    Oxygen diffusion in natural, non-metamict zircon was characterized under both dry and water-present conditions at temperatures ranging from 765°C to 1500°C. Dry experiments were performed at atmospheric pressure by encapsulating polished zircon samples with a fine powder of 18O-enriched quartz and annealing the sealed capsules in air. Hydrothermal runs were conducted in cold-seal pressure vessels (7-70 MPa) or a piston cylinder apparatus (400-1000 MPa) on zircon samples encapsulated with both 18O-enriched quartz and 18O water. Diffusive-uptake profiles of 18O were measured in all samples with a particle accelerator, using the 18O(p, α) 15N reaction. For dry experimental conditions at 1100-1500°C, the resulting oxygen diffusivities (24 in all) are well described by: D dry (m 2/s) = 1.33 × 10 -4exp(-53920/T) There is no suggestion of diffusive anisotropy. Under wet conditions at 925°C, oxygen diffusion shows little or no dependence upon P H 2O in the range 7-1000 MPa, and is insensitive to total pressure as well. The results of 27 wet experiments at 767-1160°C and 7-1000 MPa can be described a single Arrhenius relationship: D wet (m 2/s) = 5.5 × 10 -12exp(-25280/T) The insensitivity of oxygen diffusion to P H 2O means that applications to geologic problems can be pursued knowing only whether the system of interest was 'wet' (i.e., P H 2O > 7MPa ) or 'dry'. Under dry conditions (presumably rare in the crust), zircons are extremely retentive of their oxygen isotopic signatures, to the extent that δ 18O would be perturbed at the center of a 200 μm zircon only during an extraordinarily hot and protracted event (e.g., 65 Ma at 900°C). Under wet conditions, δ 18O may or may not be retained in the central regions of individual crystals, cores or overgrowth rims, depending upon the specific thermal history of the system.

  7. Hereditary Diffuse Gastric Cancer

    Science.gov (United States)

    ... Hereditary Diffuse Gastric Cancer Request Permissions Hereditary Diffuse Gastric Cancer Approved by the Cancer.Net Editorial Board , 10/2017 What is hereditary diffuse gastric cancer? Hereditary diffuse gastric cancer (HDGC) is a rare ...

  8. Atmospheric Electricity

    Science.gov (United States)

    Aplin, Karen; Fischer, Georg

    2018-02-01

    Electricity occurs in atmospheres across the Solar System planets and beyond, spanning spectacular lightning displays in clouds of water or dust, to more subtle effects of charge and electric fields. On Earth, lightning is likely to have existed for a long time, based on evidence from fossilized lightning strikes in ancient rocks, but observations of planetary lightning are necessarily much more recent. The generation and observations of lightning and other atmospheric electrical processes, both from within-atmosphere measurements, and spacecraft remote sensing, can be readily studied using a comparative planetology approach, with Earth as a model. All atmospheres contain charged molecules, electrons, and/or molecular clusters created by ionization from cosmic rays and other processes, which may affect an atmosphere's energy balance both through aerosol and cloud formation, and direct absorption of radiation. Several planets are anticipated to host a "global electric circuit" by analogy with the circuit occurring on Earth, where thunderstorms drive current of ions or electrons through weakly conductive parts of the atmosphere. This current flow may further modulate an atmosphere's radiative properties through cloud and aerosol effects. Lightning could potentially have implications for life through its effects on atmospheric chemistry and particle transport. It has been observed on many of the Solar System planets (Earth, Jupiter, Saturn, Uranus, and Neptune) and it may also be present on Venus and Mars. On Earth, Jupiter, and Saturn, lightning is thought to be generated in deep water and ice clouds, but discharges can be generated in dust, as for terrestrial volcanic lightning, and on Mars. Other, less well-understood mechanisms causing discharges in non-water clouds also seem likely. The discovery of thousands of exoplanets has recently led to a range of further exotic possibilities for atmospheric electricity, though lightning detection beyond our Solar System

  9. Modeling soil CO2 production and transport with dynamic source and diffusion terms: testing the steady-state assumption using DETECT v1.0

    Science.gov (United States)

    Ryan, Edmund M.; Ogle, Kiona; Kropp, Heather; Samuels-Crow, Kimberly E.; Carrillo, Yolima; Pendall, Elise

    2018-05-01

    The flux of CO2 from the soil to the atmosphere (soil respiration, Rsoil) is a major component of the global carbon (C) cycle. Methods to measure and model Rsoil, or partition it into different components, often rely on the assumption that soil CO2 concentrations and fluxes are in steady state, implying that Rsoil is equal to the rate at which CO2 is produced by soil microbial and root respiration. Recent research, however, questions the validity of this assumption. Thus, the aim of this work was two-fold: (1) to describe a non-steady state (NSS) soil CO2 transport and production model, DETECT, and (2) to use this model to evaluate the environmental conditions under which Rsoil and CO2 production are likely in NSS. The backbone of DETECT is a non-homogeneous, partial differential equation (PDE) that describes production and transport of soil CO2, which we solve numerically at fine spatial and temporal resolution (e.g., 0.01 m increments down to 1 m, every 6 h). Production of soil CO2 is simulated for every depth and time increment as the sum of root respiration and microbial decomposition of soil organic matter. Both of these factors can be driven by current and antecedent soil water content and temperature, which can also vary by time and depth. We also analytically solved the ordinary differential equation (ODE) corresponding to the steady-state (SS) solution to the PDE model. We applied the DETECT NSS and SS models to the six-month growing season period representative of a native grassland in Wyoming. Simulation experiments were conducted with both model versions to evaluate factors that could affect departure from SS, such as (1) varying soil texture; (2) shifting the timing or frequency of precipitation; and (3) with and without the environmental antecedent drivers. For a coarse-textured soil, Rsoil from the SS model closely matched that of the NSS model. However, in a fine-textured (clay) soil, growing season Rsoil was ˜ 3 % higher under the assumption of

  10. A general advection-diffusion model for radioactive substance dispersion released from nuclear power plants

    International Nuclear Information System (INIS)

    Buske, D.

    2011-01-01

    The present contribution focuses on the question of radioactive material dispersion after discharge from a nuclear power plant in the context of micro-meteorology, i.e. an atmospheric dispersion model. The advection-diffusion equation with Fickian closure for the turbulence is solved for the atmospheric boundary layer where the eddy diffusivity coefficients and the wind profile are assumed to be space dependent. The model is solved in closed form using integral transform and spectral theory. Convergence of the solution is discussed in terms of a convergence criterion using a new interpretation of the Cardinal Theorem of Interpolation theory and Parseval's theorem. The solution is compared to other methods and model adequacy is analyzed. Model validation is performed against experimental data from a controlled release of radioactive material at the Itaorna Beach (Angra dos Reis, Rio de Janeiro state, Brazil, 1985). (author)

  11. Positron annihilation in solids: positronium diffusion; Annihilation du positon dans les solides diffusion du positonium

    Energy Technology Data Exchange (ETDEWEB)

    Paulin, R. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1969-04-01

    The existence of two slow components in life-time spectrum of positron annihilation in silicium, aluminium and alkaline-earth oxides powders is established. These two long mean-lives {approx_equal} 10{sup -9} s and {approx_equal} 10{sup -7} s result from annihilation, inside and outside the grains respectively, of ortho-positronium formed in defects present in ionic crystals investigated. Dynamic behaviour of Ps, so revealed, is analyzed in terms of diffusion in excellent agreement with experiment. Diffusion constants of the order of 10{sup -4} cm{sup 2} sec{sup -1} and mean path before annihilation from 50 to 300 Angstrom are measured. From 100 to 500 K the temperature influence upon diffusion process is effective only in SiO{sub 2} where activation energy is found about 10{sup -2} eV. The p-Ps zero point energy evaluated by angular correlation gives the order of magnitude for defects dimensions and diffusion mean-time. Finally, o-Ps behaviour in space between grains, where its interaction with atmospheric gases can be only detected, is analysed. (author) [French] Nous mettons en evidence l'existence de deux composantes lentes dans le spectre de temps de vie du positon avant annihilation dans des poudres d'oxydes alcalinoterreux d'alumine et de silice. Ces deux longues vies moyennes {approx_equal} 10{sup -9} s et {approx_equal} 10{sup -7} s resultent respectivement de l'annihilation a l'interieur et a l'exterieur des grains de l'ortho-positonium forme dans certains defauts presents dans les cristaux ioniques etudies. L'analyse des proprietes dynamiques du Ps ainsi revelees, est effectuee en termes de diffusion en excellent accord avec l'experience. Des constantes de diffusion de l'ordre de 10{sup -4} cm{sup 2} sec{sup -1} et des parcours moyens avant annihilation variant de 50 a 300 Angstrom sont ainsi mesures. Entre 100 et 500 K l'influence de la temperature sur le processus de diffusion n'est sensible

  12. Mars: Atmosphere

    Science.gov (United States)

    Moroz, V.; Murdin, P.

    2001-07-01

    The atmosphere of MARS is much thinner than the terrestrial one. However, even the simplest visual telescopic observations show a set of atmospheric events such as seasonal exchange of material between polar caps, temporal appearance of clouds and changes of visibility of dark regions on the disk of the planet. In 1947 the prominent CO2 bands in the near-infrared part of the Martian spectrum were...

  13. Solutions for a non-Markovian diffusion equation

    International Nuclear Information System (INIS)

    Lenzi, E.K.; Evangelista, L.R.; Lenzi, M.K.; Ribeiro, H.V.; Oliveira, E.C. de

    2010-01-01

    Solutions for a non-Markovian diffusion equation are investigated. For this equation, we consider a spatial and time dependent diffusion coefficient and the presence of an absorbent term. The solutions exhibit an anomalous behavior which may be related to the solutions of fractional diffusion equations and anomalous diffusion.

  14. Non-Local Diffusion of Energetic Electrons during Solar Flares

    Science.gov (United States)

    Bian, N. H.; Emslie, G.; Kontar, E.

    2017-12-01

    The transport of the energy contained in suprathermal electrons in solar flares plays a key role in our understanding of many aspects of flare physics, from the spatial distributions of hard X-ray emission and energy deposition in the ambient atmosphere to global energetics. Historically the transport of these particles has been largely treated through a deterministic approach, in which first-order secular energy loss to electrons in the ambient target is treated as the dominant effect, with second-order diffusive terms (in both energy and angle) generally being either treated as a small correction or even neglected. Here, we critically analyze this approach, and we show that spatial diffusion through pitch-angle scattering necessarily plays a very significant role in the transport of electrons. We further show that a satisfactory treatment of the diffusion process requires consideration of non-local effects, so that the electron flux depends not just on the local gradient of the electron distribution function but on the value of this gradient within an extended region encompassing a significant fraction of a mean free path. Our analysis applies generally to pitch-angle scattering by a variety of mechanisms, from Coulomb collisions to turbulent scattering. We further show that the spatial transport of electrons along the magnetic field of a flaring loop can be modeled as a Continuous Time Random Walk with velocity-dependent probability distribution functions of jump sizes and occurrences, both of which can be expressed in terms of the scattering mean free path.

  15. Effect of coatings on long term behaviour of a commercial stainless steel for solid oxide electrolyser cell interconnect application in H2/H2O atmosphere

    International Nuclear Information System (INIS)

    Ardigo, M.R.; Popa, I.; Chevalier, S.; Girardon, P.; Perry, F.; Laucournet, R.; Brevet, A.; Desgranges, C.

    2014-01-01

    K41X (AISI 441) stainless steel evidenced a high electrical conductivity after 3000 h ageing in H 2 /H 2 O side when used as interconnect for solid oxide electrolyser cells (SOEC) working at 800 C. Perovskite (La 1-x Sr x MnO 3-δ ) and spinel (Co 3 O 4 ) oxides coatings were applied on the surface of the ferritic steel for ageing at 800 C for 3000 h. Both coatings improved the behaviour of the steel and give interesting opportunities to use the K41X steel as interconnect for hydrogen production via high temperature steam electrolysis. Co 3 O 4 reduced into Co leading to a very good Area Specific Resistance (ASR) parameter, 0.038 Ωcm 2 . Despite a good ASR (0.06 Ωcm 2 ), La 1-x Sr x MnO 3-δ was less promising because it partially decomposed into MnO and La 2 O 3 during ageing in H 2 /H 2 O atmosphere. (authors)

  16. The effect of reduced atmospheric deposition on soil and soil solution chemistry at a site subjected to long-term acidification, Nacetin, Czech Republic

    Czech Academy of Sciences Publication Activity Database

    Oulehle, F.; Hofmeister, J.; Cudlín, Pavel; Hruška, J.

    2006-01-01

    Roč. 370, 2-3 (2006), s. 532-544 ISSN 0048-9697 R&D Projects: GA ČR(CZ) GA526/03/0058 Institutional research plan: CEZ:AV0Z60870520 Keywords : long-term monitoring Norway spruce * Recovery * Soil solution * Base cations * Nitrogen * Norway spruce Subject RIV: DD - Geochemistry Impact factor: 2.359, year: 2006

  17. Atmospheric Photochemistry

    Science.gov (United States)

    Massey, Harrie; Potter, A. E.

    1961-01-01

    The upper atmosphere offers a vast photochemical laboratory free from solid surfaces, so all reactions take place in the gaseous phase. At 30 km altitude the pressure has fallen to about one-hundredth of that at ground level, and we shall, rather arbitrarily, regard the upper atmosphere as beginning at that height. By a little less than 100 km the pressure has fallen to 10(exp -3) mm Hg and is decreasing by a power of ten for every 15 km increase in altitude. Essentially we are concerned then with the photochemistry of a nitrogen-oxygen mixture under low-pressure conditions in which photo-ionization, as well as photodissociation, plays an important part. Account must also be taken of the presence of rare constituents, such as water vapour and its decomposition products, including particularly hydroxyl, oxides of carbon, methane and, strangely enough, sodium, lithium and calcium. Many curious and unfamiliar reactions occur in the upper atmosphere. Some of them are luminescent, causing the atmosphere to emit a dim light called the airglow. Others, between gaseous ions and neutral molecules, are almost a complete mystery at this time. Similar interesting phenomena must occur in other planetary atmospheres, and they might be predicted if sufficient chemical information were available.

  18. Long term trends in atmospheric concentrations of polycyclic aromatic hydrocarbons and nitropolycyclic aromatic hydrocarbons: A study of Japanese cities from 1997 to 2014.

    Science.gov (United States)

    Hayakawa, Kazuichi; Tang, Ning; Nagato, Edward Gou; Toriba, Akira; Sakai, Shigekatsu; Kano, Fumio; Goto, Sumio; Endo, Osamu; Arashidani, Kei-Ichi; Kakimoto, Hitoshi

    2018-02-01

    Total suspended particulate matter (TSP) was collected during the summer and winter in five Japanese cities spanning Hokkaido to Kyushu (Sapporo, Kanazawa, Tokyo, Sagamihara and Kitakyushu) from 1997 to 2014. Nine polycyclic aromatic hydrocarbons (PAHs) with four to six rings, including pyrene (Pyr) and benzo[a]pyrene (BaP), were identified using high-performance liquid chromatography (HPLC) with fluorescence detection. Two nitropolycyclic aromatic hydrocarbons (NPAHs), 1-nitropyrene (1-NP) and 6-nitrobenzo[a]pyrene (6-NBaP), were identified by HPLC with chemiluminescence detection. A comparison of PAH and NPAH concentrations and [NPAH]/[PAH] ratios such as [1-NP]/[Pyr] and [6-NBaP]/[BaP] revealed the following characteristics in the five cities: (1) In Sapporo, Kanazawa, Tokyo and Sagamihara, the concentrations of PAHs and NPAHs were high at the beginning of the sampling period and then steadily decreased, with NPAHs decreasing faster than PAHs. The large initial [1-NP]/[Pyr] ratios suggest that the major contributor was automobiles but subsequent decreases in this ratio suggest decreased automobile contributions. (2) By contrast, PAH concentrations in Kitakyushu did not decrease during the sampling period, though concentrations of NPAHs decreased. The consistently smaller [1-NP]/[Pyr] ratio and larger [6-NBaP]/[BaP] ratio in Kitakyushu suggests that the major contributor of PAHs was not automobiles but iron manufacturing which uses a large amount of coal. The sudden increase in atmospheric PAH concentrations in the winter of 2014 may also be due to iron manufacturing. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. Atmospheric emissions of Cu and Zn from coal combustion in China: Spatio-temporal distribution, human health effects, and short-term prediction.

    Science.gov (United States)

    Li, Rui; Li, Junlin; Cui, Lulu; Wu, Yu; Fu, Hongbo; Chen, Jianmin; Chen, Mindong

    2017-10-01

    China has become the largest coal consumer and important emitter of trace metals in the world. A multiple-year inventory of atmospheric copper (Cu) and zinc (Zn) emissions from coal combustion in 30 provinces of China and 4 economic sectors (power plant, industry sector, residential sector, and others) for the period of 1995-2014 has been calculated. The results indicated that the total emissions of Cu and Zn increased from 5137.70 t and 11484.16 t in 1995-7099.24 t and 14536.61 t in 2014, at an annual average growth rate of 1.90% and 1.33%, respectively. The industrial sector ranked as the leading source, followed by power plants, the residential use, and other sectors. The emissions of Cu and Zn were predominantly concentrated in the northern and eastern regions of China due to the enormous consumption of coal by the industrial and the power sectors. The emissions of Cu and Zn were closely associated with mortality and life expectancy (LE) on the basis of multiple regression analysis. Spatial econometric models suggested that Cu and Zn emissions displayed significantly positive relevance with mortality, while they exhibited negative correlation with LE. The influence of the Cu emission peaked in the north of China for both mortality and LE, while the impacts of the Zn emission on mortality and LE reached a maximum value in Xinjiang Province. The results of the grey prediction model suggested that the Cu emission would decrease to 5424.73 t, whereas the Zn emissions could reach 17402.13 t in 2020. Analysis of more specific data are imperative in order to estimate the emissions of both metals, to assess their human health effects, and then to adopt effective measures to prevent environmental pollution. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Global atmospheric changes.

    Science.gov (United States)

    Piver, W T

    1991-12-01

    Increasing concentrations of CO2 and other greenhouse gases in the atmosphere can be directly related to global warming. In terms of human health, because a major cause of increasing atmospheric concentrations of CO2 is the increased combustion of fossil fuels, global warming also may result in increases in air pollutants, acid deposition, and exposure to ultraviolet (UV) radiation. To understand better the impacts of global warming phenomena on human health, this review emphasizes the processes that are responsible for the greenhouse effect, air pollution, acid deposition, and increased exposure to UV radiation.

  1. Atmospheric thermodynamics

    CERN Document Server

    Iribarne, J V

    1973-01-01

    The thermodynamics of the atmosphere is the subject of several chapters in most textbooks on dynamic meteorology, but there is no work in English to give the subject a specific and more extensive treatment. In writing the present textbook, we have tried to fill this rather remarkable gap in the literature related to atmospheric sciences. Our aim has been to provide students of meteorology with a book that can playa role similar to the textbooks on chemical thermodynamics for the chemists. This implies a previous knowledge of general thermodynamics, such as students acquire in general physics courses; therefore, although the basic principles are reviewed (in the first four chapters), they are only briefly discussed, and emphasis is laid on those topics that will be useful in later chapters, through their application to atmospheric problems. No attempt has been made to introduce the thermodynamics of irreversible processes; on the other hand, consideration of heterogeneous and open homogeneous systems permits a...

  2. Atmospheric pollution

    International Nuclear Information System (INIS)

    Lambrozo, J.; Guillossou, G.

    2008-01-01

    The atmosphere is the reservoir of numerous pollutants (nitrogen oxides, sulfur oxides, carbon oxides, particulates, volatile organic compounds, polycyclic aromatic hydrocarbons) from natural origin or anthropogenic origin ( industry, transport, agriculture, district heating). With epidemiologic studies the atmospheric pollution is associated with an increase of respiratory and cardiovascular diseases. At the european level, the technological progress, the legislation have allowed a reduction of pollutant emissions, however these efforts have to be continued because the sanitary impact of atmospheric pollution must not be underestimated, even if the risks appear less important that these ones in relation with tobacco, inside pollution or others factors of cardiovascular risks. Indeed, on these last factors an individual action is possible for the exposure to air pollution people have no control. (N.C.)

  3. Nonsurgical giant cell tumour of the tendon sheath or of the diffuse type: Are MRI or 18F-FDG PET/CT able to provide an accurate prediction of long-term outcome?

    International Nuclear Information System (INIS)

    Dercle, Laurent; Chisin, Roland; Ammari, Samy; Gillebert, Quentin; Ouali, Monia; Jaudet, Cyril; Dierickx, Lawrence; Zerdoud, Slimane; Courbon, Frederic; Delord, Jean-Pierre; Schlumberger, Martin

    2015-01-01

    To investigate whether MRI (RECIST 1.1, WHO criteria and the volumetric approach) or 18 F-FDG PET/CT (PERCIST 1.0) are able to predict long-term outcome in nonsurgical patients with giant cell tumour of the tendon sheath or of the diffuse type (GCT-TS/DT). Fifteen ''nonsurgical'' patients with a histological diagnosis of GCT-TS/DT were divided into two groups: symptomatic patients receiving targeted therapy and asymptomatic untreated patients. All 15 patients were evaluated by MRI of whom 10 were treated, and a subgroup of 7 patients were evaluated by PET/CT of whom 4 were treated. Early evolution was assessed according to MRI and PET/CT scans at baseline and during follow-up. Cohen's kappa coefficient was used to evaluate the degree of agreement between PERCIST 1.0, RECIST 1.1, WHO criteria, volumetric approaches and the reference standard (long-term outcome, delay 505 ± 457 days). The response rate in symptomatic patients with GCT-TS/DT receiving targeted therapy was also assessed in a larger population that included additional patients obtained from a review of the literature. The kappa coefficients for agreement between RECIST/WHO/volumetric criteria and outcome (15 patients) were respectively: 0.35 (p = 0.06), 0.26 (p = 0.17) and 0.26 (p = 0.17). In the PET/CT subgroup (7 patients), PERCIST was in perfect agreement with the late symptomatic evolution (kappa = 1, p 18 F-FDG PET/CT with PERCIST is a promising approach to the prediction of the long-term outcome in GCT-TS/DT and may avoid unnecessary treatments, toxicity and costs. On MRI, WHO and volumetric approaches are not more effective than RECIST using the current thresholds. (orig.)

  4. Diffusion zinc plating of structural steels

    International Nuclear Information System (INIS)

    Kazakovskaya, Tatiana; Goncharov, Ivan; Tukmakov, Victor; Shapovalov, Vyacheslav

    2004-01-01

    The report deals with the research on diffusion zinc plating of structural steels when replacing their cyanide cadmium plating. The results of the experiments in the open air, in vacuum, in the inert atmosphere, under various temperatures (300 - 500 deg.C) for different steel brands are presented. It is shown that diffusion zinc plating in argon or nitrogen atmosphere ensures obtaining the qualitative anticorrosion coating with insignificant change of mechanical properties of steels. The process is simple, reliable, ecology pure and cost-effective. (authors)

  5. Prediction of diffuse solar irradiance using machine learning and multivariable regression

    International Nuclear Information System (INIS)

    Lou, Siwei; Li, Danny H.W.; Lam, Joseph C.; Chan, Wilco W.H.

    2016-01-01

    Highlights: • 54.9% of the annual global irradiance is composed by its diffuse part in HK. • Hourly diffuse irradiance was predicted by accessible variables. • The importance of variable in prediction was assessed by machine learning. • Simple prediction equations were developed with the knowledge of variable importance. - Abstract: The paper studies the horizontal global, direct-beam and sky-diffuse solar irradiance data measured in Hong Kong from 2008 to 2013. A machine learning algorithm was employed to predict the horizontal sky-diffuse irradiance and conduct sensitivity analysis for the meteorological variables. Apart from the clearness index (horizontal global/extra atmospheric solar irradiance), we found that predictors including solar altitude, air temperature, cloud cover and visibility are also important in predicting the diffuse component. The mean absolute error (MAE) of the logistic regression using the aforementioned predictors was less than 21.5 W/m"2 and 30 W/m"2 for Hong Kong and Denver, USA, respectively. With the systematic recording of the five variables for more than 35 years, the proposed model would be appropriate to estimate of long-term diffuse solar radiation, study climate change and develope typical meteorological year in Hong Kong and places with similar climates.

  6. Planar Dirac diffusion

    International Nuclear Information System (INIS)

    Leo, Stefano de; Rotelli, Pietro

    2009-01-01

    We present the results of the planar diffusion of a Dirac particle by step and barrier potentials, when the incoming wave impinges at an arbitrary angle with the potential. Except for right-angle incidence this process is characterized by the appearance of spin flip terms. For the step potential, spin flip occurs for both transmitted and reflected waves. However, we find no spin flip in the transmitted barrier result. This is surprising because the barrier result may be derived directly from a two-step calculation. We demonstrate that the spin flip cancellation indeed occurs for each ''particle'' (wave packet) contribution. (orig.)

  7. Cu2ZnSnS4 solar cells fabricated by short-term sulfurization of sputtered Sn/Zn/Cu precursors under an H2S atmosphere

    International Nuclear Information System (INIS)

    Emrani, Amin; Rajbhandari, Pravakar P.; Dhakal, Tara P.; Westgate, Charles R.

    2015-01-01

    Synthesis of Cu 2 ZnSnS 4 (CZTS) thin films by short-term sulfurization of sputtered Sn/Zn/Cu precursors under ambient H 2 S is studied. The effect of the sulfurization processes on the film morphology, surface roughness, composition of the CZTS, and the crystallinity was investigated by using scanning electron microscopy, optical profiler, energy dispersive spectroscopy, and X-ray diffraction respectively. To further explore the CZTS layer, the following additional layers were deposited to complete the solar cells: CdS with chemical bath deposition; ZnO and Al 2 O 3 -doped ZnO with RF magnetron deposition; and, silver fingers as the front contact as the last layer. The optical and morphological properties of the CZTS films were investigated and compared. Subsequently, the electrical characteristics and the efficiencies of the regarding solar cells were analyzed. A maximum efficiency of 3.8% has been obtained for the fast sulfurization (30 min at 580 °C) and finally, the performance is compared with our best cell fabricated through the more common slow annealing. - Highlights: • Development of Cu 2 ZnSnS 4 (CZTS) solar cells using elemental metal sputtering • 112-oriented CZTS films with well-defined morphology obtained • Reported efficiency of 3.8% for a short-term annealing (less than 30 min) under ambient H 2 S • A detailed comparison between the fast and the more common slow annealing is reported

  8. Long-term variations and trends in the simulation of the middle atmosphere 1980–2004 by the chemistry-climate model of the Meteorological Research Institute

    Directory of Open Access Journals (Sweden)

    M. Deushi

    2008-05-01

    Full Text Available A middle-atmosphere simulation of the past 25 years (from 1980 to 2004 has been performed with a chemistry-climate model (CCM of the Meteorological Research Institute (MRI under observed forcings of sea-surface temperature, greenhouse gases, halogens, volcanic aerosols, and solar irradiance variations. The dynamics module of MRI-CCM is a spectral global model truncated triangularly at a maximum wavenumber of 42 with 68 layers extending from the surface to 0.01 hPa (about 80 km, wherein the vertical spacing is 500 m from 100 to 10 hPa. The chemistry-transport module treats 51 species with 124 reactions including heterogeneous reactions. Transport of chemical species is based on a hybrid semi-Lagrangian scheme, which is a flux form in the vertical direction and an ordinary semi-Lagrangian form in the horizontal direction. The MRI-CCM used in this study reproduced a quasi-biennial oscillation (QBO of about a 20-month period for wind and ozone in the equatorial stratosphere. Multiple linear regression analysis with time lags for volcanic aerosols was performed on the zonal-mean quantities of the simulated result to separate the trend, the QBO, the El Chichón and Mount Pinatubo, the 11-year solar cycle, and the El Niño/Southern Oscillation (ENSO signals. It is found that MRI-CCM can more or less realistically reproduce observed trends of annual mean temperature and ozone, and those of total ozone in each month. MRI-CCM also reproduced the vertical multi-cell structures of tropical temperature, zonal-wind, and ozone associated with the QBO, and the mid-latitude total ozone QBO in each winter hemisphere. Solar irradiance variations of the 11-year cycle were found to affect radiation alone (not photodissociation because of an error in making the photolysis lookup table. Nevertheless, though the heights of the maximum temperature (ozone in the tropics are much higher (lower than observations, MRI-CCM could reproduce the second maxima of temperature and

  9. The atmospheric heat engine response to climate change

    Science.gov (United States)

    Pauluis, O. M.

    2014-12-01

    Moist convection is characterized by complex interactions between dynamics and thermodynamics. As air parcels within the atmosphere, they experience multiple thermodynamic transformations, such as compression and expansion, diabatic heating and cooling, condensation and mixing. These transformations correspond to those of a heat engine that produces kinetic energy while transporting energy from a warm source to a colder sink. This atmospheric heat engine is however directly affected by moist processes. First, falling precipitation acts as a break on the circulation by dissipating a significant amount of kinetic energy. Second, evaporation of unsaturated water and diffusion of water vapor are irrevesible processes that also reduce the amount of work that can be produced. An important challenge is to quantify the impacts that these two effects have on the generation of kinetic energy. Here, I will introduce a new technique - the Mean Air Flow As Lagragian Dynamics Approximation (MAFALDA) - that can be used to systematically analyze the thermodynamic behavior of complex atmospheric flows. This approach relies on sorting the upward mass transport in terms of the equivalent potential temperature of the air parcels to obtain an isentropic streamfunction. This streamfunction is then used to determine the thermodynamic evolution of air parcels as they move through the atmosphere. This approach is applied to analyze how convective systems would behave in a warmer climate. It is shown that an increase in atmospheric temperature lead to a significant increase of the amount of kinetic energy that is produced per unit of mass of air transported. At the same time, the total generation of kinetic energy is only slightly affected. Taken together, these findings imply that, in a warming atmosphere, the number of intense convective events will be reduced, while their intensity should increase. I will also discuss the new possibility of systematically studying the thermodynamic

  10. Tree ring δ18O reveals no long-term change of atmospheric water demand since 1800 in the northern Great Hinggan Mountains, China

    Science.gov (United States)

    Liu, Xiaohong; Zhang, Xuanwen; Zhao, Liangju; Xu, Guobao; Wang, Lixin; Sun, Weizhen; Zhang, Qiuliang; Wang, Wenzhi; Zeng, Xiaomin; Wu, Guoju

    2017-07-01

    Global warming will significantly increase transpirational water demand, which could dramatically affect plant physiology and carbon and water budgets. Tree ring δ18O is a potential index of the leaf-to-air vapor-pressure deficit (VPD) and therefore has great potential for long-term climatic reconstruction. Here we developed δ18O chronologies of two dominant native trees, Dahurian larch (Larix gmelinii Rupr.) and Mongolian pine (Pinus sylvestris var. mongolica), from a permafrost region in the Great Hinggan Mountains of northeastern China. We found that the July-August VPD and relative humidity were the dominant factors that controlled tree ring δ18O in the study region, indicating strong regulation of stomatal conductance. Based on the larch and pine tree ring δ18O chronologies, we developed a reliable summer (July-August) VPD reconstruction since 1800. Warming growing season temperatures increase transpiration and enrich cellulose 18O, but precipitation seemed to be the most important influence on VPD changes in this cold region. Periods with stronger transpirational demand occurred around the 1850s, from 1914 to 1925, and from 2005 to 2010. However, we found no overall long-term increasing or decreasing trends for VPD since 1800, suggesting that despite the increasing temperatures and thawing permafrost throughout the region, forest transpirational demand has not increased significantly during the past two centuries. Under current climatic conditions, VPD did not limit growth of larch and pine, even during extremely drought years. Our findings will support more realistic evaluations and reliable predictions of the potential influences of ongoing climatic change on carbon and water cycles and on forest dynamics in permafrost regions.

  11. Alarming atmospheres

    DEFF Research Database (Denmark)

    Højlund, Marie; Kinch, Sofie

    2014-01-01

    Nurses working in the Neuro-Intensive Care Unit at Aarhus University Hospital lack the tools to prepare children for the alarming atmosphere they will enter when visiting a hospitalised relative. The complex soundscape dominated by alarms and sounds from equipment is mentioned as the main stressor...

  12. RKC time-stepping for advection-diffusion-reaction problems

    International Nuclear Information System (INIS)

    Verwer, J.G.; Sommeijer, B.P.; Hundsdorfer, W.

    2004-01-01

    The original explicit Runge-Kutta-Chebyshev (RKC) method is a stabilized second-order integration method for pure diffusion problems. Recently, it has been extended in an implicit-explicit manner to also incorporate highly stiff reaction terms. This implicit-explicit RKC method thus treats diffusion terms explicitly and the highly stiff reaction terms implicitly. The current paper deals with the incorporation of advection terms for the explicit method, thus aiming at the implicit-explicit RKC integration of advection-diffusion-reaction equations in a manner that advection and diffusion terms are treated simultaneously and explicitly and the highly stiff reaction terms implicitly

  13. Diffusion of samarium into cobalt in the reduction-diffusion process

    International Nuclear Information System (INIS)

    Freitas Nogueira, P. de; Neto, F.B.; Landgraf, F.J.G.

    1998-01-01

    The presence of metallic cobalt in samarium-cobalt powders is a major cause for low magnetic properties in magnets. This paper intends to investigate the effect of time and temperature in the microstructure of powders produced by reduction-diffusion. This process, developed for the production of rare earth-transition metal alloys, consists on the reduction of the rare earth oxide with metallic calcium (or calcium hydride) and its subsequent diffusion into the cobalt particle. In the present work, a mixture of samarium oxide, cobalt powder and metallic calcium was heated to 1100 or 1200 C for 2 or 4 hours in a tubular furnace under one atmosphere of purified argon. The material thereof obtained, a sintered mass is disintegrated by aqueous crepitation. The powder was evaluated in terms of its chemical composition, its samarium yield and the intermetallic compounds present. The samarium, oxygen and calcium content of the powders produced were adequate for magnet production. However, despite the massive formation of the SmCo 5 compound after 2 hours at 1100 C, final homogeneity is attained only after 4 hours at 1200 C, with the presence of SmCo 5 and Sm 2 Co 7 and the absence of the Sm 5 Co 19 compound. Also, metallic cobalt and Sm 2 Co 17 were observed in the materials produced after 2 hours at 1100 or 1200 C. (orig.)

  14. New definition of the cell diffusion coefficient

    International Nuclear Information System (INIS)

    Koehler, P.

    1975-01-01

    As was shown in a recent work by Gelbard, the usually applied Benoist definition of the cell diffusion coefficient gives two different values if two different definitions of the cell are made. A new definition is proposed that preserves the neutron balance for the homogenized lattice and that is independent of the cell definition. The resulting diffusion coefficient is identical with the main term of Benoist's diffusion coefficient

  15. Long-term decrease of atmospheric test 137Cs in the soil-prairie plant-milk pathway in southern Chile

    International Nuclear Information System (INIS)

    Schuller, P.; Ellies, A.; Handl, J.

    1998-01-01

    The time dependency of nuclear test 137 Cs in soil, prairie plants, and milk was observed on pastures of seven dairy farms in the 10th Region, Chile, from 1982 to 1997, without any appreciable deposition of radioactive fallout after 1983. Whereas the 137 Cs concentration in the soil decreased at a rate close to that of the radionuclide's physical decay during the whole observation period, the rate of decrease of the 137 Cs concentration in the prairie plants and in the milk, having been very rapid between 1982--1990, became slower between 1991--1997. The effective half-lives of the concentration in plants were found to be 5.6 y and 12 y during the first and second observation periods, respectively. Similar half-lives of 5.5 y and 13 y were found for the concentration decline in milk during each period. These data clearly demonstrate a reduction in the long-term decrease of the 137 Cs plant uptake, and consequently in the decrease of the 137 Cs concentration in milk, resulting from a decline of 137 Cs availability for prairie plants in the Hapludand soils over the whole 15-y observation period

  16. Diffusion in amorphous media

    Science.gov (United States)

    Iotov, Mihail S.

    The goals of this research are twofold: First, to develop methods and tools for studying problems in chemistry, material science and biology, as well as accurate prediction of the properties of structures and materials of importance to those fields. Second, use those tools to apply the methods to practical problems. In terms of methodology development this thesis focuses on two topics: One: Development of a massively parallel computer program to perform electronic, atomic, molecular levels simulations of problems in chemistry, material science and biology. This computer program uses existing and emerging hardware platforms and parallel tools and is based on decades long research in computer modeling and algorithms. We report on that development in Chapter 3. Two: Development of tools for Molecular Dynamics simulation and methods and tools for course-grained meso-scale modeling of transport properties and especially diffusion of gas penetrants in polymers. We have formulated a new method for extracting coarse-grained information from short (0.2-0.5 nanoseconds [ns]) MD simulations and use this in a meso-scale simulation to calculate diffusion constants in polymer matrices. This is a grid-based method, which calculates the average probability of each grid point of being a void and performs constrained and biased Monte Carlo (MC) dynamics to reach much longer time regimes than possible in MD. The MC method mimics the three regimes of mean square deviation (MSD) behavior seen in MD, thus accounting for the proper mobility of the voids and the compressibility of the polymer matrix. Theoretical discussions and justification for the method is presented in chapter 6. Initial results on He diffusion in a low-density polyethylene (PE) matrix are presented in chapter 7. The behavior at different temperatures follows closely the trend observed from calibrating long term MD for this particular system.

  17. Dense-gas dispersion advection-diffusion model

    International Nuclear Information System (INIS)

    Ermak, D.L.

    1992-07-01

    A dense-gas version of the ADPIC particle-in-cell, advection- diffusion model was developed to simulate the atmospheric dispersion of denser-than-air releases. In developing the model, it was assumed that the dense-gas effects could be described in terms of the vertically-averaged thermodynamic properties and the local height of the cloud. The dense-gas effects were treated as a perturbation to the ambient thermodynamic properties (density and temperature), ground level heat flux, turbulence level (diffusivity), and windfield (gravity flow) within the local region of the dense-gas cloud. These perturbations were calculated from conservation of energy and conservation of momentum principles along with the ideal gas law equation of state for a mixture of gases. ADPIC, which is generally run in conjunction with a mass-conserving wind flow model to provide the advection field, contains all the dense-gas modifications within it. This feature provides the versatility of coupling the new dense-gas ADPIC with alternative wind flow models. The new dense-gas ADPIC has been used to simulate the atmospheric dispersion of ground-level, colder-than-ambient, denser-than-air releases and has compared favorably with the results of field-scale experiments

  18. Excess Entropy and Diffusivity

    Indian Academy of Sciences (India)

    First page Back Continue Last page Graphics. Excess Entropy and Diffusivity. Excess entropy scaling of diffusivity (Rosenfeld,1977). Analogous relationships also exist for viscosity and thermal conductivity.

  19. Memory effects in turbulent diffusion

    International Nuclear Information System (INIS)

    Zagorodny, A.G.; Weiland, J.; Wilhelmsson, H.

    1993-01-01

    A non-Markovian approach is proposed for the derivation of the diffusion coefficient of saturated turbulence. A memory term accounting for nonlocal coherence effects is introduced in a new attempt to describe the transition between weak and strong turbulence. The result compares favourably with recent experiments as well as mode coupling simulations of fusion plasmas. (14 refs.)

  20. Size dependent diffusive parameters and tensorial diffusion equations in neutronic models for optically small nuclear systems

    International Nuclear Information System (INIS)

    Premuda, F.

    1983-01-01

    Two lines in improved neutron diffusion theory extending the efficiency of finite-difference diffusion codes to the field of optically small systems, are here reviewed. The firs involves the nodal solution for tensorial diffusion equation in slab geometry and tensorial formulation in parallelepiped and cylindrical gemometry; the dependence of critical eigenvalue from small slab thicknesses is also analitically investigated and finally a regularized tensorial diffusion equation is derived for slab. The other line refer to diffusion models formally unchanged with respect to the classical one, but where new size-dependent RTGB definitions for diffusion parameters are adopted, requiring that they allow to reproduce, in diffusion approach, the terms of neutron transport global balance; the trascendental equation for the buckling, arising in slab, sphere and parallelepiped geometry from the above requirement, are reported and the sizedependence of the new diffusion coefficient and extrapolated end point is investigated

  1. Vulnerability to diffuse pollution of European soils and groundwater

    NARCIS (Netherlands)

    Meinardi CR; Beusen AHW; Bollen MJS; Klepper O; LBG; CWM

    1994-01-01

    From the Atlantic Ocean to the Ural Mountains, European soils and groundwater are threatened by diffuse pollution derived from various chemicals used in modern agriculture and by increased atmospheric deposition of pollutants. The investigated vulnerability of soils (including groundwater) to

  2. A fortran program for elastic scattering of deuterons with an optical model containing tensorial potentials; Programme fortran pour la diffusion elastique de deutons avec un modele optique contenant des termes tensoriels

    Energy Technology Data Exchange (ETDEWEB)

    Raynal, J. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1963-07-01

    The optical model has been applied with success to the elastic scattering of particles of spin 0 and 1/2 and to a lesser degree to that of deuterons. For particles of spin l/2, an LS coupling term is ordinarily used; this term is necessary to obtain a polarization; for deuterons, this coupling has been already introduced, but the possible forms of potentials are more numerous (in this case, scalar products of a second rank spin tensor with a tensor of the same rank in space or momentum can occur). These terms which may be necessary are primarily important for the tensor polarization. This problem is of particular interest at Saclay since a beam of polarized deuterons has become available. The FORTRAN program SPM 037 permits the study of the effect of tensorial potentials constructed from the distance of the deuteron from the target and its angular momentum with respect to it. This report should make possible the use and even the modification of the program. It consists of: a description of the problem and of the notation employed, a presentation of the methods adopted, an indication of the necessary data and how they should be introduced, and finally tables of symbols which are in equivalence or common statements: these tables must be considered when making any modification. (author) [French] Le modele optique a ete applique avec succes a la diffusion elastique des particules de spin nul et 1/2 et dans une moindre mesure a celle des deutons. Pour les particules de spin 1/2, on utilise habituellement un couplage LS, necessaire pour calculer la polarisation; pour les deutons, ce couplage a deja ete introduit, mais les formes de potentiel possibles sont plus nombreuses (intervention de produits scalaires d'un tenseur d'ordre 2 de spin avec un tenseur du meme ordre d'espace ou d'impulsion) et celles qui peuvent etre eventuellement necessaires ont une importance capitale pour la polarisation tensorielle. Ce probleme revet a Saclay un interet

  3. A fortran program for elastic scattering of deuterons with an optical model containing tensorial potentials; Programme fortran pour la diffusion elastique de deutons avec un modele optique contenant des termes tensoriels

    Energy Technology Data Exchange (ETDEWEB)

    Raynal, J [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1963-07-01

    The optical model has been applied with success to the elastic scattering of particles of spin 0 and 1/2 and to a lesser degree to that of deuterons. For particles of spin l/2, an LS coupling term is ordinarily used; this term is necessary to obtain a polarization; for deuterons, this coupling has been already introduced, but the possible forms of potentials are more numerous (in this case, scalar products of a second rank spin tensor with a tensor of the same rank in space or momentum can occur). These terms which may be necessary are primarily important for the tensor polarization. This problem is of particular interest at Saclay since a beam of polarized deuterons has become available. The FORTRAN program SPM 037 permits the study of the effect of tensorial potentials constructed from the distance of the deuteron from the target and its angular momentum with respect to it. This report should make possible the use and even the modification of the program. It consists of: a description of the problem and of the notation employed, a presentation of the methods adopted, an indication of the necessary data and how they should be introduced, and finally tables of symbols which are in equivalence or common statements: these tables must be considered when making any modification. (author) [French] Le modele optique a ete applique avec succes a la diffusion elastique des particules de spin nul et 1/2 et dans une moindre mesure a celle des deutons. Pour les particules de spin 1/2, on utilise habituellement un couplage LS, necessaire pour calculer la polarisation; pour les deutons, ce couplage a deja ete introduit, mais les formes de potentiel possibles sont plus nombreuses (intervention de produits scalaires d'un tenseur d'ordre 2 de spin avec un tenseur du meme ordre d'espace ou d'impulsion) et celles qui peuvent etre eventuellement necessaires ont une importance capitale pour la polarisation tensorielle. Ce probleme revet a Saclay un interet particulier depuis la mise

  4. Diffusing diffusivity: Rotational diffusion in two and three dimensions

    Science.gov (United States)

    Jain, Rohit; Sebastian, K. L.

    2017-06-01

    We consider the problem of calculating the probability distribution function (pdf) of angular displacement for rotational diffusion in a crowded, rearranging medium. We use the diffusing diffusivity model and following our previous work on translational diffusion [R. Jain and K. L. Sebastian, J. Phys. Chem. B 120, 3988 (2016)], we show that the problem can be reduced to that of calculating the survival probability of a particle undergoing Brownian motion, in the presence of a sink. We use the approach to calculate the pdf for the rotational motion in two and three dimensions. We also propose new dimensionless, time dependent parameters, αr o t ,2 D and αr o t ,3 D, which can be used to analyze the experimental/simulation data to find the extent of deviation from the normal behavior, i.e., constant diffusivity, and obtain explicit analytical expressions for them, within our model.

  5. Diffusion in solids

    International Nuclear Information System (INIS)

    Tiwari, G.P.; Kale, G.B.; Patil, R.V.

    1999-01-01

    The article presents a brief survey of process of diffusion in solids. It is emphasised that the essence of diffusion is the mass transfer through the atomic jumps. To begin with formal equations for diffusion coefficient are presented. This is followed by discussions on mechanisms of diffusion. Except for solutes which form interstitial solid solution, diffusion in majority of cases is mediated through exchange of sites between an atom and its neighbouring vacancy. Various vacancy parameters such as activation volume, correlation factor, mass effect etc are discussed and their role in establishing the mode of diffusion is delineated. The contribution of dislocations and grain boundaries in diffusion process is brought out. The experimental determination of different types of diffusion coefficients are described. Finally, the pervasive nature of diffusion process in number of commercial processes is outlined to show the importance of diffusion studies in materials science and technology. (author)

  6. Diffusion archeology for diffusion progression history reconstruction

    OpenAIRE

    Sefer, Emre; Kingsford, Carl

    2015-01-01

    Diffusion through graphs can be used to model many real-world processes, such as the spread of diseases, social network memes, computer viruses, or water contaminants. Often, a real-world diffusion cannot be directly observed while it is occurring — perhaps it is not noticed until some time has passed, continuous monitoring is too costly, or privacy concerns limit data access. This leads to the need to reconstruct how the present state of the diffusion came to be from partial d...

  7. Modelling the environmental transport of tritium in the vicinity of long term atmospheric and sub-surface sources. Report of the Tritium Working Group of the Biosphere Modelling and Assessment (BIOMASS) Programme, Theme 3

    International Nuclear Information System (INIS)

    2003-03-01

    The IAEA Programme on BIOsphere Modelling and ASSessment (BIOMASS) was launched in Vienna in October 1996. The programme was concerned with developing and improving capabilities to predict the transfer of radionuclides in the environment. The programme had three themes: Theme 1: Radioactive Waste Disposal. The objective was to develop the concept of a standard or reference biosphere for application to the assessment of the long term safety of repositories for radioactive waste. Theme 2: Environmental Releases. BIOMASS provided an international forum for activities aimed at increasing the confidence in methods and models for the assessment of radiation exposure related to environmental releases. Two Working Groups addressed issues concerned with the reconstruction of radiation doses received by people from past releases of radionuclides to the environment and the evaluation of the efficacy of remedial measures. Theme 3: Biosphere Processes. The aim of this Theme was to improve capabilities for modelling the transfer of radionuclides in particular parts of the biosphere identified as being of potential radiological significance and where there were gaps in modelling approaches. This topic was explored using a range of methods including reviews of the literature, model inter-comparison exercises and, where possible, model testing against independent sources of data. Three Working Groups were established to examine the modelling of: (1) long term tritium dispersion in the environment; (2) radionuclide uptake by fruits; and (3) radionuclide migration and accumulation in forest ecosystems. This report describes results of the studies undertaken by the Tritium Working Group under Theme 3. It discusses the six model test exercises (three model-model intercomparisons and three model-data exercises) and the twenty-month field sampling programme undertaken to investigate the environmental transport of tritium in the vicinity of long term atmospheric and sub-surface sources

  8. Atmospheric sciences annual progress report, 1974

    International Nuclear Information System (INIS)

    Tucker, W.D.

    1975-11-01

    Activities in atmospheric sciences in the Department of Applied Science at Brookhaven National Laboratory carried out during 1974 are described. Included are contributions from the Meteorology, Atmospheric Diagnostics, Atmospheric Chemistry Research, and Atmospheric Instrumentation Groups. Programs in Meteorology reported on include diffusion from an off-shore source, plume dynamics studies, modeling of coastal effects on wind and temperature fields and pollutant distributions, effects of indoor shelter on inhalation of airborne radionuclides, chemical-dynamical interactions, techniques for determining acid-rain impact upon the ecology of the eastern U.S., and climatology. Work under Atmospheric Chemistry Research was concentrated on atmospheric aerosol studies, including formation by free radical and neutral association reactions, identification of reactive systems leading to aerosol formation, growth of sodium aerosols under atmospheric conditions and clustering reactions. Atmospheric Diagnostics presents work on field sampling and analytical technology for atmospheric pollutants, airborne sampling systems, atmospheric sulfate particulates methodology, and on a pyroturbidometric method for particulate sulfate discrimination and determination. Methodology for the use of sulfur hexafluoride in field tracer studies is discussed under Atmospheric Instrumentation. A list of publications is included

  9. Understanding deterministic diffusion by correlated random walks

    International Nuclear Information System (INIS)

    Klages, R.; Korabel, N.

    2002-01-01

    Low-dimensional periodic arrays of scatterers with a moving point particle are ideal models for studying deterministic diffusion. For such systems the diffusion coefficient is typically an irregular function under variation of a control parameter. Here we propose a systematic scheme of how to approximate deterministic diffusion coefficients of this kind in terms of correlated random walks. We apply this approach to two simple examples which are a one-dimensional map on the line and the periodic Lorentz gas. Starting from suitable Green-Kubo formulae we evaluate hierarchies of approximations for their parameter-dependent diffusion coefficients. These approximations converge exactly yielding a straightforward interpretation of the structure of these irregular diffusion coefficients in terms of dynamical correlations. (author)

  10. Single Crystal Diffuse Neutron Scattering

    Directory of Open Access Journals (Sweden)

    Richard Welberry

    2018-01-01

    Full Text Available Diffuse neutron scattering has become a valuable tool for investigating local structure in materials ranging from organic molecular crystals containing only light atoms to piezo-ceramics that frequently contain heavy elements. Although neutron sources will never be able to compete with X-rays in terms of the available flux the special properties of neutrons, viz. the ability to explore inelastic scattering events, the fact that scattering lengths do not vary systematically with atomic number and their ability to scatter from magnetic moments, provides strong motivation for developing neutron diffuse scattering methods. In this paper, we compare three different instruments that have been used by us to collect neutron diffuse scattering data. Two of these are on a spallation source and one on a reactor source.

  11. Numerical methods of estimating the dispersion of radionuclides in atmosphere

    International Nuclear Information System (INIS)

    Vladu, Mihaela; Ghitulescu, Alina; Popescu, Gheorghe; Piciorea, Iuliana

    2007-01-01

    Full text: The paper presents the method of dispersion calculation, witch can be applied for the DLE calculation. This is necessary to ensure a secure performance of the Experimental Pilot Plant for Tritium and Deuterium Separation (using the technology for detritiation based upon isotope catalytic exchange between tritiated heavy water and deuterium followed by cryogenic distillation of the hydrogen isotopes). For the calculation of the dispersion of radioactivity effluents in the atmosphere, at a given distance between source and receiver, the Gaussian mathematical model was used. This model is currently applied for estimating the long-term results of dispersion in case of continuous or intermittent emissions as basic information for long-term radioprotection measures for areas of the order of kilometres from the source. We have considered intermittent or continuous emissions of intensity lower than 1% per day relative to the annual emission. It is supposed that the radioactive material released into environment presents a gaussian dispersion both in horizontal and vertical plan. The local dispersion parameters could be determined directly with turbulence measurements or indirectly by determination of atmospheric stability. Weather parameters for characterizing the atmospheric dispersion include: - direction of wind relative to the source; - the speed of the wind at the height of emission; - parameters of dispersion to different distances, depending on the atmospheric turbulence which characterizes the mixing of radioactive materials in the atmosphere; - atmospheric stability range; - the height of mixture stratum; - the type and intensity of precipitations. The choice of the most adequate version of Gaussian model depends on the relation among the height where effluent emission is in progress, H (m), and the height at which the buildings influence the air motion, HB (m). There were defined three zones of distinct dispersion. This zones can have variable lengths

  12. Test emission of uranium hexafluoride in atmosphere. Results interpretation

    International Nuclear Information System (INIS)

    Crabol, B.; Deville-Cavelin, G.

    1989-01-01

    To permit the modelization of gaseous uranium hexafluoride behaviour in atmosphere, a validation test has been executed the 10 April 1987. The experimental conditions, the main results and a comparison with a diffusion model are given in this report [fr

  13. Latitudinal Variation of Germane in Jovian Atmosphere

    Science.gov (United States)

    Hyder, A.; Lunine, J. I.; Wang, D.

    2017-12-01

    Wang et al (2016) presented a chemical-dynamical model for Jupiter's atmosphere that predicted abundances of Germane and other disequilibrium species as a function of latitude, under the assumption that only vertical transport is relevant and no horizontal advection occurs. The model disagrees with the latitudinal distributions derived from high-resolution spectral data acquired from the CRIRES instrument at the VLT as described in Giles et al. 2017. Wang et al. 2016 predicts a maximum molar abundance of Germane at (0.7±0.2) ppb with depletion at higher latitudes, while Giles et al. 2017 predicts a constant molar abundance of Germane at 0.58 ppb with no depletion. We explore an empirical horizontal term for the diffusive transport coefficient as a function of latitude, which does not produce a satisfactory result unless highly arbitrary variations of the vertical eddy mixing term as a function of latitude are imposed. We therefore also explore a horizontal wind from the equator that produces a constant latitudinal profile by transporting Germane-rich gas to the poles, effectively producing a Hadley cell. References: Giles, R. S., Fletcher, L. N., & Irwin, P. G. (2017). Latitudinal variability in Jupiter's tropospheric disequilibrium species: GeH 4, AsH 3 and PH 3. Icarus, 289, 254-269. Wang, D., Lunine, J.I., Mousis, O., 2016. Modeling the disequilibrium species for Jupiter and Saturn: implications for Juno and Saturn entry probe. Icarus 276, 21-38.

  14. Titan's hydrodynamically escaping atmosphere

    Science.gov (United States)

    Strobel, Darrell F.

    2008-02-01

    The upper atmosphere of Titan is currently losing mass at a rate ˜(4-5)×10 amus, by hydrodynamic escape as a high density, slow outward expansion driven principally by solar UV heating by CH 4 absorption. The hydrodynamic mass loss is essentially CH 4 and H 2 escape. Their combined escape rates are restricted by power limitations from attaining their limiting rates (and limiting fluxes). Hence they must exhibit gravitational diffusive separation in the upper atmosphere with increasing mixing ratios to eventually become major constituents in the exosphere. A theoretical model with solar EUV heating by N 2 absorption balanced by HCN rotational line cooling in the upper thermosphere yields densities and temperatures consistent with the Huygens Atmospheric Science Investigation (HASI) data [Fulchignoni, M., and 42 colleagues, 2005. Nature 438, 785-791], with a peak temperature of ˜185-190 K between 3500-3550 km. This model implies hydrodynamic escape rates of ˜2×10 CHs and 5×10 Hs, or some other combination with a higher H 2 escape flux, much closer to its limiting value, at the expense of a slightly lower CH 4 escape rate. Nonthermal escape processes are not required to account for the loss rates of CH 4 and H 2, inferred by the Cassini Ion Neutral Mass Spectrometer (INMS) measurements [Yelle, R.V., Borggren, N., de la Haye, V., Kasprzak, W.T., Niemann, H.B., Müller-Wodarg, I., Waite Jr., J.H., 2006. Icarus 182, 567-576].

  15. Spin-diffusions and diffusive molecular dynamics

    Science.gov (United States)

    Farmer, Brittan; Luskin, Mitchell; Plecháč, Petr; Simpson, Gideon

    2017-12-01

    Metastable configurations in condensed matter typically fluctuate about local energy minima at the femtosecond time scale before transitioning between local minima after nanoseconds or microseconds. This vast scale separation limits the applicability of classical molecular dynamics (MD) methods and has spurned the development of a host of approximate algorithms. One recently proposed method is diffusive MD which aims at integrating a system of ordinary differential equations describing the likelihood of occupancy by one of two species, in the case of a binary alloy, while quasistatically evolving the locations of the atoms. While diffusive MD has shown itself to be efficient and provide agreement with observations, it is fundamentally a model, with unclear connections to classical MD. In this work, we formulate a spin-diffusion stochastic process and show how it can be connected to diffusive MD. The spin-diffusion model couples a classical overdamped Langevin equation to a kinetic Monte Carlo model for exchange amongst the species of a binary alloy. Under suitable assumptions and approximations, spin-diffusion can be shown to lead to diffusive MD type models. The key assumptions and approximations include a well-defined time scale separation, a choice of spin-exchange rates, a low temperature approximation, and a mean field type approximation. We derive several models from different assumptions and show their relationship to diffusive MD. Differences and similarities amongst the models are explored in a simple test problem.

  16. Diffusion with social reinforcement: The role of individual preferences

    NARCIS (Netherlands)

    Tur, Elena M.; Zeppini, Paolo; Frenken, Koen

    2018-01-01

    The debate on diffusion in social networks has traditionally focused on the structure of the network to understand the efficiency of a network in terms of diffusion. Recently, the role of social reinforcement has been added to the debate, as it has been proposed that simple contagions diffuse better

  17. Nonlinear analysis of a reaction-diffusion system: Amplitude equations

    Energy Technology Data Exchange (ETDEWEB)

    Zemskov, E. P., E-mail: zemskov@ccas.ru [Russian Academy of Sciences, Dorodnicyn Computing Center (Russian Federation)

    2012-10-15

    A reaction-diffusion system with a nonlinear diffusion term is considered. Based on nonlinear analysis, the amplitude equations are obtained in the cases of the Hopf and Turing instabilities in the system. Turing pattern-forming regions in the parameter space are determined for supercritical and subcritical instabilities in a two-component reaction-diffusion system.

  18. Diffusion in reactor materials

    International Nuclear Information System (INIS)

    Fedorov, G.B.; Smirnov, E.A.

    1984-01-01

    The monograph contains a brief description of the principles underlying the theory of diffusion, as well as modern methods of studying diffusion. Data on self-diffusion and diffusion of impurities in a nuclear fuel and fissionable materials (uranium, plutonium, thorium, zirconium, titanium, hafnium, niobium, molybdenum, tungsten, beryllium, etc.) is presented. Anomalous diffusion, diffusion of components, and interdiffusion in binary and ternary alloys were examined. The monograph presents the most recent reference material on diffusion. It is intended for a wide range of researchers working in the field of diffusion in metals and alloys and attempting to discover new materials for application in nuclear engineering. It will also be useful for teachers, research scholars and students of physical metallurgy

  19. CROSS DIFFUSION AND NONLINEAR DIFFUSION PREVENTING BLOW UP IN THE KELLER–SEGEL MODEL

    KAUST Repository

    CARRILLO, JOSÉ ANTONIO; HITTMEIR, SABINE; JÜ NGEL, ANSGAR

    2012-01-01

    A parabolic-parabolic (Patlak-)Keller-Segel model in up to three space dimensions with nonlinear cell diffusion and an additional nonlinear cross-diffusion term is analyzed. The main feature of this model is that there exists a new entropy

  20. Atmospheric characteristics essential for health effects modeling

    International Nuclear Information System (INIS)

    Nelson, N.S.

    1977-01-01

    Factors to be considered in evaluating the possible consequences of exposure of human populations to radioactive aerosols are reviewed. Mathematical models of the mechanisms of radioinduced carcinogenesis, tissue deposition and lung clearance of radioactive aerosols, and meteorological parameters affecting the diffusion of radioactive aerosols in the atmosphere are discussed

  1. Diffusion in flowing gas

    International Nuclear Information System (INIS)

    Reus, K.W.

    1979-01-01

    This thesis is concerned with the back-diffusion method of calculating the mutual diffusion coefficient of two gases. The applicability of this method for measuring diffusion coefficients at temperatures up to 1300 K is considered. A further aim of the work was to make a contribution to the description of the interatomic potential energy of noble gases at higher energies as a function of the internuclear distance. This was achieved with the measured diffusion coefficients, especially with those for high temperatures. (Auth.)

  2. Diffusion Under Geometrical Constraint

    OpenAIRE

    Ogawa, Naohisa

    2014-01-01

    Here we discus the diffusion of particles in a curved tube. This kind of transport phenomenon is observed in biological cells and porous media. To solve such a problem, we discuss the three dimensional diffusion equation with a confining wall forming a thinner tube. We find that the curvature appears in a effective diffusion coefficient for such a quasi-one-dimensional system. As an application to higher dimensional case, we discuss the diffusion in a curved surface with ...

  3. THE ISOTROPIC DIFFUSION SOURCE APPROXIMATION FOR SUPERNOVA NEUTRINO TRANSPORT

    International Nuclear Information System (INIS)

    Liebendoerfer, M.; Whitehouse, S. C.; Fischer, T.

    2009-01-01

    Astrophysical observations originate from matter that interacts with radiation or transported particles. We develop a pragmatic approximation in order to enable multidimensional simulations with basic spectral radiative transfer when the available computational resources are not sufficient to solve the complete Boltzmann transport equation. The distribution function of the transported particles is decomposed into a trapped particle component and a streaming particle component. Their separate evolution equations are coupled by a source term that converts trapped particles into streaming particles. We determine this source term by requiring the correct diffusion limit for the evolution of the trapped particle component. For a smooth transition to the free streaming regime, this 'diffusion source' is limited by the matter emissivity. The resulting streaming particle emission rates are integrated over space to obtain the streaming particle flux. Finally, a geometric estimate of the flux factor is used to convert the particle flux to the streaming particle density, which enters the evaluation of streaming particle-matter interactions. The efficiency of the scheme results from the freedom to use different approximations for each particle component. In supernovae, for example, reactions with trapped particles on fast timescales establish equilibria that reduce the number of primitive variables required to evolve the trapped particle component. On the other hand, a stationary-state approximation considerably facilitates the treatment of the streaming particle component. Different approximations may apply in applications to stellar atmospheres, star formation, or cosmological radiative transfer. We compare the isotropic diffusion source approximation with Boltzmann neutrino transport of electron flavor neutrinos in spherically symmetric supernova models and find good agreement. An extension of the scheme to the multidimensional case is also discussed.

  4. Diffuse ceiling ventilation

    DEFF Research Database (Denmark)

    Zhang, Chen

    Diffuse ceiling ventilation is an innovative ventilation concept where the suspended ceiling serves as air diffuser to supply fresh air into the room. Compared with conventional ventilation systems, diffuse ceiling ventilation can significantly reduce or even eliminate draught risk due to the low...

  5. On the influence of neutral turbulence on ambipolar diffusivities deduced from meteor trail expansion

    Directory of Open Access Journals (Sweden)

    C. M. Hall

    Full Text Available By measuring fading times of radar echoes from underdense meteor trails, it is possible to deduce the ambipolar diffusivities of the ions responsible for these radar echoes. It could be anticipated that these diffusivities increase monotonically with height akin to neutral viscosity. In practice, this is not always the case. Here, we investigate the capability of neutral turbulence to affect the meteor trail diffusion rate.

    Key words. Meteorology and atmospheric dynamics (middle atmosphere dynamics; turbulence

  6. On the influence of neutral turbulence on ambipolar diffusivities deduced from meteor trail expansion

    Directory of Open Access Journals (Sweden)

    C. M. Hall

    2002-11-01

    Full Text Available By measuring fading times of radar echoes from underdense meteor trails, it is possible to deduce the ambipolar diffusivities of the ions responsible for these radar echoes. It could be anticipated that these diffusivities increase monotonically with height akin to neutral viscosity. In practice, this is not always the case. Here, we investigate the capability of neutral turbulence to affect the meteor trail diffusion rate.Key words. Meteorology and atmospheric dynamics (middle atmosphere dynamics; turbulence

  7. Study of the diffusion of iron, of silver and of carbon in beryllium using radioactive tracers; Etude de la diffusion du fer, de l'argent et du carbone dans le beryllium au moyen des traceurs radioactifs

    Energy Technology Data Exchange (ETDEWEB)

    Naik, M Ch [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1964-06-01

    A study has been made of the diffusion of radioactive iron and silver tracers in beryllium. The following values have been found. D{sub Fe} = 0.53 exp - [51800 / RT], D{sub Ag} = 62 exp - [46100 / RT]. The values for iron are in good agreement with those found previously for chemical diffusion. A comparison of the diffusion coefficients for iron, silver and nickel shows that the diffusion rate increases with increasing solute atom radius. The existence has been shown of diffusion anisotropy for silver; it has been studied quantitatively on monocrystals. It is found that: D{sub parallel} 0.41 exp - [39100 / RT], D{sub perpendicular} = 1.98 exp - [45700 / RT]. The anisotropy decreases as the temperature increases. The silver diffuses more rapidly along the C axis than in the base plane. This result cannot be explained in terms of the model proposed for the diffusion of foreign atoms in solution in zinc. A greater number of experiments is required before a model can be put forward. An attempt has also been made to determine the diffusion coefficients of carbon in beryllium by treatment in an atmosphere of acetylene marked with C-14. Diffusion coefficients have been obtained but these should not be considered to be very significant since a chemical reaction occurs at the surface of the samples. (author) [French] On a etudie la diffusion dans le beryllium de traceurs radioactifs du fer et de l'argent. On trouve: D{sub Fe} = 0.53 exp - [51800 / RT], D{sub Ag} = 62 exp - [46100 / RT].Les valeurs trouvees pour le fer sont en bon accord avec les valeurs obtenues precedemment pour la diffusion chimique. La comparaison des coefficients de diffusion du fer, de l'argent et du nickel montre que la diffusion est d'autant plus rapide que le rayon atomique du solute est plus grand. On a mis en evidence une anisotropie de diffusion de l'argent qui a ete etudiee quantitativement sur des monocristaux. On trouve: D{sub parallele} = 0.41 exp - [39100 / RT], D{sub perpendiculaire} = 1

  8. Diffusion and evaporation of a liquid droplet

    Science.gov (United States)

    Shukla, K. N.

    1980-06-01

    The process of evaporation and diffusion of a spherical liquid droplet in an atmosphere of noncondensable gas is studied theoretically. An equation for the shrinkage of the radius of the droplet is derived on the basis of continuity and momentum equations. Further, a conjugate problem consisting of the energy and mass balance for the gaseous environment is formulated. An approximation of thin thermal and diffusion boundary-layers is introduced to simplify the analysis. Results are presented for methanol-nitrogen, ammonia-nitrogen, and sodium-argon systems. It has been observed that the droplet of highly viscous fluid exhibits rapid contraction.

  9. Modeling seasonal changes of atmospheric carbon dioxide and carbon 13

    International Nuclear Information System (INIS)

    Gillette, D.A.; Box, E.O.

    1986-01-01

    A two-dimensional (latitude-altitude) model of atmospheric CO 2 and δ 13 C was constructed to simulate some features of seasonal carbon cycle fluctuations. The model simulates air-sea exchange, atmospheric diffusion, and fossil fuel carbon sources, which are functions of time and latitude. In addition, it uses biosphere-atmosphere fluxes of carbon that are based on global-scale biological models of vegetation growth and decay. Results of the model show fair agreement with observational results for CO 2 and δ 13 C seasonal fluctuations. Their model results have far northern fluctuations with smaller amplitudes than are observed. Analysis of sources of CO 2 change at given latitudes shows that, for far southern latitudes, southern hemisphere biospheric fluxes are dominant in affecting the seasonal CO 2 fluctuations. Long-term decrease of δ 13 C for the model is larger than for observations. This may be due to errors in the formulation for oceanic fluxes for 13 C in the model or to a net uptake of carbon by the biosphere

  10. Atmospheric chemistry and climate

    OpenAIRE

    Satheesh, SK

    2012-01-01

    Atmospheric chemistry is a branch of atmospheric science where major focus is the composition of the Earth's atmosphere. Knowledge of atmospheric composition is essential due to its interaction with (solar and terrestrial) radiation and interactions of atmospheric species (gaseous and particulate matter) with living organisms. Since atmospheric chemistry covers a vast range of topics, in this article the focus is on the chemistry of atmospheric aerosols with special emphasis on the Indian reg...

  11. Turbulent diffusion of small particles

    International Nuclear Information System (INIS)

    Margolin, L.G.

    1977-11-01

    The diffusion of small, spherical, rigid particles suspended in an incompressible turbulent fluid, but not interacting with each other, was studied. As a stochastic process, the turbulent fluid velocity field is assumed to be homogeneous, isotropic and stationary. Assuming the Stokes regime, a particle of equation of motion is used which includes only the effects of Stokes drag and a virtual mass force and an exact solution is found for the particle velocity correlation function, for all times and initial conditions, in terms of a fluid velocity correlation function measured along the motion of the particle. This shows that for times larger than a certain time scale, the particle velocity correlation becomes stationary. The effect of small shears in the fluid velocity was considered, under the additional restrictions of a certain high frequency regime for the turbulence. The shears convected past the particle much faster than the growth of the boundary layer. New force terms due to the presence of such shears are calculated and incorporated into the equation of motion. A perturbation solution to this equation is constructed, and the resultant particle velocity correlation function and diffusion coefficient are calculated. To lowest order, the particle diffusivity is found to be unaltered by the presence of small mean flow shears. The last model treated is one in which particles traverse a turbulent fluid with a large mean velocity. Among other restrictions, linearized form drag is assumed. The diffusion coefficient for such particles was calculated, and found to be much smaller than the passive scalar diffusion coefficient. This agrees within 5 percent with the experimental results of Snyder and Lumley

  12. Atmospheric anomalies in summer 1908: Water in the atmosphere

    Science.gov (United States)

    Gladysheva, O. G.

    2011-10-01

    A gigantic noctilucent cloud field was formed and different solar halos were observed after the Tunguska catastrophe. To explain these anomalous phenomena, it is necessary to assume that a large quantity of water was carried into the atmosphere, which indicates that the Tunguska cosmic body was of a comet origin. According to rough estimates, the quantity of water that is released into the atmosphere as a result of a cosmic body's destruction is more than 1010 kg. The observation of a flying object in an area with a radius of ≥700 km makes it possible to state that the Tunguska cosmic body looked like a luminous coma with a diameter not smaller than ≥10 km and became visible at heights of >500 km. The assumption that the Tunguska cosmic body started disintegrating at a height of ˜1000 km explains the formation of an area where its mater diffused and formed a luminous area above Europe.

  13. Intermittent Motion, Nonlinear Diffusion Equation and Tsallis Formalism

    Directory of Open Access Journals (Sweden)

    Ervin K. Lenzi

    2017-01-01

    Full Text Available We investigate an intermittent process obtained from the combination of a nonlinear diffusion equation and pauses. We consider the porous media equation with reaction terms related to the rate of switching the particles from the diffusive mode to the resting mode or switching them from the resting to the movement. The results show that in the asymptotic limit of small and long times, the spreading of the system is essentially governed by the diffusive term. The behavior exhibited for intermediate times depends on the rates present in the reaction terms. In this scenario, we show that, in the asymptotic limits, the distributions for this process are given by in terms of power laws which may be related to the q-exponential present in the Tsallis statistics. Furthermore, we also analyze a situation characterized by different diffusive regimes, which emerges when the diffusive term is a mixing of linear and nonlinear terms.

  14. Balancing atmospheric carbon dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Goreau, T.J. (Discovery Bay Marine Laboratory, Univ. of the West Indies (JM))

    1990-01-01

    Rising carbon dioxide and global temperatures are causing increasing worldwide concern, and pressure towards an international law of the atmosphere is rapidly escalating, yet widespread misconceptions about the greenhouse effect's inevitability, time scale, and causes have inhibited effective consensus and action. Observations from Antarctic ice cores, Amazonian rain forests, and Carribean coral reefs suggest that the biological effects of climate change may be more severe than climate models predict. Efforts to limit emissions from fossil-fuel combustion alone are incapable of stabilizing levels of carbon dioxide in the atmosphere. Stabilizing atmospheric carbon dioxide requires coupled measures to balance sources and sinks of the gas, and will only be viable with large-scale investments in increased sustainable productivity on degraded tropical soils, and in long-term research on renewable energy and biomass product development in the developing countries. A mechanism is outlined which directly links fossil-fuel combustion sources of carbon dioxide to removal via increasing biotic productivity and storage. A preliminary cost-benefit analysis suggests that such measures are very affordable, costing far less than inaction. (With 88 refs.).

  15. Balancing atmospheric carbon dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Goreau, T J [Discovery Bay Marine Laboratory, Univ. of the West Indies (JM)

    1990-01-01

    Rising carbon dioxide and global temperatures are causing increasing worldwide concern, and pressure towards an international law of the atmosphere is rapidly escalating, yet widespread misconceptions about the greenhouse effect's inevitability, time scale, and causes have inhibited effective consensus and action. Observations from Antarctic ice cores, Amazonian rain forests, and Carribean coral reefs suggest that the biological effects of climate change may be more severe than climate models predict. Efforts to limit emissions from fossil-fuel combustion alone are incapable of stabilizing levels of carbon dioxide in the atmosphere. Stabilizing atmospheric carbon dioxide requires coupled measures to balance sources and sinks of the gas, and will only be viable with large-scale investments in increased sustainable productivity on degraded tropical soils, and in long-term research on renewable energy and biomass product development in the developing countries. A mechanism is outlined which directly links fossil-fuel combustion sources of carbon dioxide to removal via increasing biotic productivity and storage. A preliminary cost-benefit analysis suggests that such measures are very affordable, costing far less than inaction. (With 88 refs.).

  16. Determination of gas diffusion coefficients in undisturbed Boom clay

    International Nuclear Information System (INIS)

    Jacops, E.; Volckaert, G.; Maes, N.; Govaerts, J.; Weetjens, E.

    2012-01-01

    Document available in extended abstract form only. The Belgian agency for radioactive waste and enriched fissile materials Ondraf/Niras presently considers Boom Clay as a potential host formation for the disposal of high-level and long-lived radioactive waste. The production of gas is unavoidable within a geological repository. Gas is produced by different mechanisms: anaerobic corrosion of metals in waste and packaging, radiolysis of water and organic materials in the waste and engineered barriers and microbial degradation of various organic wastes. Corrosion and radiolysis yield mainly hydrogen while microbial degradation leads to methane and carbon dioxide. The gas generated in the near field of a geological repository will dissolve in the pore water and is transported away from the repository by diffusion as dissolved species. If the gas generation rate is larger than the diffusive flux, the pore water will become over-saturated and a free gas phase will form. Initially, isolated gas bubbles will accumulate until a continuous gas phase is formed. As gas pressure continues to increase, discrete gas pathways may be formed by tensile fractures within the rock fabric. Consequently, this entire process may locally and at least temporarily alter the hydraulic and mechanical properties of the engineered barriers and the clay and, perhaps, their performance. Therefore it is important to assess whether or not gas production rates might exceed the diffusive gas flux. The currently available gas diffusion parameters (D eff : effective diffusion coefficient) for hydrogen in Boom Clay, obtained from the MEGAS project, and re-evaluated after lead to an estimated D eff between 1.9 10 -12 and 1.5 10 -10 m 2 /s. Sensitivity calculations showed that this uncertainty on the diffusion coefficient, combined with that on the gas source term, made it impossible to exclude the formation of a free gas phase. To reduce the uncertainty, an experimental method was developed to determine

  17. Thermal diffusion (1963); Diffusion thermique (1963)

    Energy Technology Data Exchange (ETDEWEB)

    Lemarechal, A [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1963-07-01

    This report brings together the essential principles of thermal diffusion in the liquid and gaseous phases. The macroscopic and molecular aspects of the thermal diffusion constant are reviewed, as well as the various measurement method; the most important developments however concern the operation of the CLUSIUS and DICKEL thermo-gravitational column and its applications. (author) [French] Ce rapport rassemble les principes essentiels de la diffusion thermique en phase liquide et en phase gazeuse. Les aspects macroscopique et moleculaire de la constante de diffusion thermique sont passes en revue ainsi que ses differentes methodes de mesure; mais les developpements les plus importants concernent le fonctionnement de ls colonne thermogravitationnelle de CLUSIUS et DICKEL et ses applications. (auteur)

  18. Fractional diffusion equations and anomalous diffusion

    CERN Document Server

    Evangelista, Luiz Roberto

    2018-01-01

    Anomalous diffusion has been detected in a wide variety of scenarios, from fractal media, systems with memory, transport processes in porous media, to fluctuations of financial markets, tumour growth, and complex fluids. Providing a contemporary treatment of this process, this book examines the recent literature on anomalous diffusion and covers a rich class of problems in which surface effects are important, offering detailed mathematical tools of usual and fractional calculus for a wide audience of scientists and graduate students in physics, mathematics, chemistry and engineering. Including the basic mathematical tools needed to understand the rules for operating with the fractional derivatives and fractional differential equations, this self-contained text presents the possibility of using fractional diffusion equations with anomalous diffusion phenomena to propose powerful mathematical models for a large variety of fundamental and practical problems in a fast-growing field of research.

  19. On OH production in water containing atmospheric pressure plasmas

    NARCIS (Netherlands)

    Bruggeman, P.J.; Schram, D.C.

    2010-01-01

    In this paper radical production in atmospheric pressure water containing plasmas is discussed. As OH is often an important radical in these discharges the paper focuses on OH production. Besides nanosecond pulsed coronas and diffusive glow discharges, several other atmospheric pressure plasmas

  20. Atmospheric neutrinos and the νe/νμ ratio

    International Nuclear Information System (INIS)

    Portella, H.M.; Maldonado, R.H.C.; Gomes, A.

    1994-01-01

    This work calculates analytically the atmospheric neutrino flux by solving the one-dimensional equations which describe the hadrons and leptons diffusion in the atmosphere, and compares the results with those obtained by using simulation calculations performed by Gaisser and coworkers, and analytically obtained by Bugaev and Naumov

  1. The bibliometrics of atmospheric environment

    Science.gov (United States)

    Brimblecombe, Peter; Grossi, Carlota M.

    Bibliometric analysis is an important tool in the management of a journal. SCOPUS output is used to assess the increase in the quantity of material in Atmospheric Environment and stylistic changes in the way authors choose words and punctuation in titles and assemble their reference lists. Citation analysis is used to consider the impact factor of the journal, but perhaps more importantly the way in which it reflects the importance authors give to papers published in Atmospheric Environment. The impact factor of Atmospheric Environment (2.549 for 2007) from the Journal Citation Reports suggests it performs well within the atmospheric sciences, but it conceals the long term value authors place on papers appearing in the journal. Reference lists show that a fifth come through citing papers more than a decade old.

  2. Interaction between ionization and gravity waves in the upper atmosphere

    International Nuclear Information System (INIS)

    Balcioglu, O.

    1982-10-01

    It is known that travelling ionospheric disturbances are produced by gravity waves. During their movement from the F region downwards to the E region, gravity waves can produce thin layers called transients on ionograms and, if the wave motion persists, 'h-type Esub(S) can be produced. To investigate the problem, the continuity equations for both the E and F regions are solved for a perturbation, the motion of which is taken to be a gravity wave. Hitherto, N'/N 0 , the ratio of the disturbed to the undisturbed electron density, has been calculated by using only the Hall conductivity and ignoring the diffusion term for the F region. In the present calculations we have used Pedersan and Hall conductivities and calculated the N'/N 0 ratio for both the E and F regions. Using CIRA standard atmosphere data we find for the F region that N' can exceed N 0 by up to 4 percent, depending on the horizontal wind velocity. In the E region, N' reaches much higher values than in the F region. Thus at 120 km if we take a typical horizontal wind velocity of 80 m/sec (wavelength 150 km), N' is about twice as large as N 0 . From these results we see that the diffusion term is important for the E region. (author)

  3. Diffusion in molybdenum disilicide

    International Nuclear Information System (INIS)

    Salamon, M.; Mehrer, H.

    2005-01-01

    The diffusion behaviour of the high-temperature material molybdenum disilicide (MoSi 2 ) was completely unknown until recently. In this paper we present studies of Mo self-diffusion and compare our present results with our already published studies of Si and Ge diffusion in MoSi 2 . Self-diffusion of molybdenum in monocrystalline MoSi 2 was studied by the radiotracer technique using the radioisotope 99 Mo. Deposition of the radiotracer and serial sectioning after the diffusion anneals to determine the concentration-depth profiles was performed using a sputtering device. Diffusion of Mo is a very slow process. In the entire temperature region investigated (1437 to 2173 K), the 99 Mo diffusivities in both principal directions of the tetragonal MoSi 2 crystals obey Arrhenius laws, where the diffusion perpendicular to the tetragonal axis is faster by two to three orders of magnitude than parallel to it. The activation enthalpies for diffusion perpendicular and parallel to the tetragonal axis are Q perpendicular to = 468 kJ mol -1 (4.85 eV) and Q parallel = 586 kJ mol -1 (6.07 eV), respectively. Diffusion of Si and its homologous element Ge is fast and is mediated by thermal vacancies of the Si sublattice of MoSi 2 . The diffusion of Mo is by several orders of magnitude slower than the diffusion of Si and Ge. This large difference suggests that Si and Mo diffusion are decoupled and that the diffusion of Mo likely takes place via vacancies on the Mo sublattice. (orig.)

  4. Analysis on the atmospheric dispersion of radioactive materials

    International Nuclear Information System (INIS)

    Nagai, Haruyasu

    2012-01-01

    JAEA has been developing a new prediction system of comprehensive movement, SPEEDI-MP (SPEEDI Multi-model Package), which can treat continuously and strictly with the migration behavior of radioactive materials at atmosphere, sea, and land region. JAEA has been further promoting the detail analysis of atmospheric migration of radioactive materials dispersed by an accident. Then, using a part of this system, the atmospheric-diversion prediction system, WSPEEDI-II, the atmospheric diversion mass and the atmospheric diffusion analysis were carried out. This issue reports the summary. (M.H.)

  5. Knowledge Diffusion in a Grade 4-5 Classroom during a Unit on Civil Engineering: An Analysis of a Classroom Community in Terms of Its Changing Resources and Practices.

    Science.gov (United States)

    Roth, Wolff-Michael

    1996-01-01

    Employed the actor network theory to examine the transformation of a grade-four classroom community as new resources and practices became available. Found that the diffusion and enculturation metaphors are insufficient to model important aspects of learning in a student-centered classroom. (MOK)

  6. The diffusion of radioactive gases in the meso-scale (20 km-400 km)

    International Nuclear Information System (INIS)

    Wippermann, F.

    1974-01-01

    The term ''Mesoscale'' refers to distances between 20 km and 400 km from the source; in defining this range, the structure of atmospheric turbulence is taken into account. To arrive at an evaluation of diffusion in the mesoscale, quantitative methods from the microscale (source distance 400 km) are extrapolated into the mesoscale. In the first case a table is given to read off the minimum factor by which the concentration is reduced in the mesoscale as the source distance increases to obtain the diffusion for the worst possible case, the existence of a mixing-layer topped by a temperature inversion, was assumed. For this it was essential, first of all, to determine the source distance xsub(D) beyond which the diffusing gases are completely mixed within the mixing-layer of thickness D. To make allowance for all possible thicknesses of this mixing-layer, a measurement carried out at ground level at only 10 km from the source can be used to calculate the correct concentrations in the mixing-layer; the dilution factors will then be related to this value. Possible ways of an improved incorporation of certain factors in the diffusion estimate, such as the topography of the earth's surface, the roughness of terrain, the vertical profiles of wind and exchange coefficients and the effects of non-stability are given in the last section

  7. Understanding differences in the diffusion of environmentally beneficial technology. Final project report

    Energy Technology Data Exchange (ETDEWEB)

    Blackman, A.; Boyd, J.; Simpson, R.D.; Toman, M.

    1996-12-31

    The factors affecting the diffusion of technical discoveries among firms and nations remain one of the most interesting and important but least understood elements of economic behavior. Recently, interest in technology diffusion has been heightened by a recognition that the spread of technologies could have important implications for environmental quality as well as for market goods and services. A specific motivation for this study was the question of how rapidly technologies that reduce greenhouse gas emissions might diffuse. Technologies in this category include technologies that improve the efficiency of fossil energy use or promote substitution of renewable energy resources. The speed with which these technologies spread could have a significant effect on the rate of accumulation of carbon in the atmosphere. From a modeling perspective, the rate of innovation and diffusion of carbon-reducing technology is known to be a crucial parameter in integrated assessments of climate change risks and policy responses. Thus, a better understanding of factors that might influence the spread of carbon-reducing technologies could be valuable in studies on long-term global change and policy assessment.

  8. Distribution of positive ion species above a diffuse midnight aurora

    International Nuclear Information System (INIS)

    Moore, T.E.

    1978-01-01

    The origin of the hot plasma in the Earth's magnetosphere is still open to investigation. Mass composition is an indicator of source region, while the distribution functions bear the signatures of transport and energization processes. Only ions identified as H + and He ++ were detected, and the He ++ was statistically marginal. Coincident magnetic storms are likely to play a crucial role in populating the magnetosphere with energized ionospheric ions. The measured proton distribution was nearly isotropic over downcoming pitch angles at all energies and showed a depleted atmospheric source cone. The high-altitude proton energy distribution had a best fit temperature of 4.5 keV and a number density of 0.17 cm- 3 , corresponding to a peak intensity just over 10 5 cm -2 s -1 sr -1 keV -1 . Altitudinal variations are consistent with the theory of charge exchange of a time-steady incident proton population. Simultaneous electron measurements can be interpreted in terms of an incident electron distribution that is also thermal wih a similar number density but a temperature of 2.5 keV. Taken together, the ion and electron data are consistent with the model of diffuse auroras in which plasma convecting in from the magnetospheric tail precipitates due to strong pitch angle diffusion on auroral field lines linking the near Earth plasma sheet

  9. Diffusion of hydrogen in iron oxides

    International Nuclear Information System (INIS)

    Bruzzoni, P.

    1993-01-01

    The diffusion of hydrogen in transitions metals oxides has been recently studied at room temperature through the permeability electrochemical technique. This work studies thin oxide layers grown in air or in presence of oxidizing atmospheres at temperatures up to 200 deg C. The substrate was pure iron with different superficial treatments. It was observed that these oxides reduce up to three magnitudes orders, the hydrogen stationary flux through membranes of usual thickness in comparison with iron membranes free of oxide. (Author)

  10. Diffusion coefficients for unattached decay products of thoron - dependence on ventilation and relative humidity

    International Nuclear Information System (INIS)

    Kotrappa, P.; Bhanti, D.P.; Raghunath, B.

    1976-01-01

    The results of a study of the diffusivity of unattached decay products of thoron with respect to air changes using a recently developed diffusion sampler are reported. The dependence of diffusivity of radon/thoron decay products on relative humidity has also been investigated by measurement of diffusion coefficients in an atmosphere where relative humidities varied from 5 to 90%. Results are shown tabulated. (U.K.)

  11. Metric diffusion along foliations

    CERN Document Server

    Walczak, Szymon M

    2017-01-01

    Up-to-date research in metric diffusion along compact foliations is presented in this book. Beginning with fundamentals from the optimal transportation theory and the theory of foliations; this book moves on to cover Wasserstein distance, Kantorovich Duality Theorem, and the metrization of the weak topology by the Wasserstein distance. Metric diffusion is defined, the topology of the metric space is studied and the limits of diffused metrics along compact foliations are discussed. Essentials on foliations, holonomy, heat diffusion, and compact foliations are detailed and vital technical lemmas are proved to aide understanding. Graduate students and researchers in geometry, topology and dynamics of foliations and laminations will find this supplement useful as it presents facts about the metric diffusion along non-compact foliation and provides a full description of the limit for metrics diffused along foliation with at least one compact leaf on the two dimensions.

  12. Atmospheric diffusion and dose estimation for habitability assessments

    International Nuclear Information System (INIS)

    Xing Fuli; Li Xu

    1993-01-01

    The assessment of Emergency Centre has a bearing on the implementing of Emergency plan, and is of great significance. So the calculation procedure and models concerning the normalized concentration (X/Q) in the building wakes are becoming very important. A model which is different from the currently used is used to assess the habitability of Emergency Centre of a certain power plant in China. (4 figs., 3 tabs.)

  13. Heavy water leak detection using diffusion sampler

    International Nuclear Information System (INIS)

    Joshi, M.L.; Hussain, S.A.

    1990-01-01

    In the Pressurrised Heavy Water Reactors (PHWRs) detection of the sources of heavy water leaks is importent both for the purpose of radiation hazard control as well as for the reduction of escape/loss of heavy water which, is an expensive nuclear material. This paper describes an application of tritium diffusion sampler for heavy water leak detection. The diffusion sampler comprises an usual tritium counting glass vial with a special orifice. The counting vial has water vapour, deficient in HTO concentration. The HTO present outside diffuses in the vial through the orifice, gets exchanged with water of the wet filter paper kept at the bottom and the moisture in the vial atmosphere which has HTO concentration lower than that outside. This results in continuation of net movement of HTO in the vial. The exchanged tritium is counted in liquid scintillation spectrometer. The method has a sensitivity of 10000 dpm/DAC-h. (author). 2 figs., 2 ta bs

  14. Experimental study of radon and thoron diffusion through barriers

    Energy Technology Data Exchange (ETDEWEB)

    Durcik, M; Havlik, F [Inst. of Preventive and Clinical Medicine, 83301 Bratislava (Slovakia)

    1996-12-31

    The measurement results of diffusion parameters for radon (radon-222) and thoron (radon-220) through barriers, experimental equipment and theoretical background of diffusion are presented in this paper. The diffusion barriers are used for measuring radon and thoron by passive detectors in order to test the reduction techniques in houses. Six samples (filter paper, rubber, polyethylene, glass laminate, polypropylene) were studied for radon diffusion. The thickness barriers were from 0.012 mm to 2 mm, the diffusion area was 16 cm{sup 2} and the volume V{sub 2} was 30 dm{sup 3}. The diffusion constants D were obtained using given expressions and the data from measurements. The procedures used in experiments are useful for study of diffusion ability of radon and thoron in barriers and determination diffusion parameters from short term measurements. (J.K.). 2 figs., 1 tab., 3 refs.

  15. Experimental study of radon and thoron diffusion through barriers

    International Nuclear Information System (INIS)

    Durcik, M.; Havlik, F.

    1995-01-01

    The measurement results of diffusion parameters for radon (radon-222) and thoron (radon-220) through barriers, experimental equipment and theoretical background of diffusion are presented in this paper. The diffusion barriers are used for measuring radon and thoron by passive detectors in order to test the reduction techniques in houses. Six samples (filter paper, rubber, polyethylene, glass laminate, polypropylene) were studied for radon diffusion. The thickness barriers were from 0.012 mm to 2 mm, the diffusion area was 16 cm 2 and the volume V 2 was 30 dm 3 . The diffusion constants D were obtained using given expressions and the data from measurements. The procedures used in experiments are useful for study of diffusion ability of radon and thoron in barriers and determination diffusion parameters from short term measurements. (J.K.). 2 figs., 1 tab., 3 refs

  16. Correlated diffusion imaging

    International Nuclear Information System (INIS)

    Wong, Alexander; Glaister, Jeffrey; Cameron, Andrew; Haider, Masoom

    2013-01-01

    Prostate cancer is one of the leading causes of cancer death in the male population. Fortunately, the prognosis is excellent if detected at an early stage. Hence, the detection and localization of prostate cancer is crucial for diagnosis, as well as treatment via targeted focal therapy. New imaging techniques can potentially be invaluable tools for improving prostate cancer detection and localization. In this study, we introduce a new form of diffusion magnetic resonance imaging called correlated diffusion imaging, where the tissue being imaged is characterized by the joint correlation of diffusion signal attenuation across multiple gradient pulse strengths and timings. By taking into account signal attenuation at different water diffusion motion sensitivities, correlated diffusion imaging can provide improved delineation between cancerous tissue and healthy tissue when compared to existing diffusion imaging modalities. Quantitative evaluation using receiver operating characteristic (ROC) curve analysis, tissue class separability analysis, and visual assessment by an expert radiologist were performed to study correlated diffusion imaging for the task of prostate cancer diagnosis. These results are compared with that obtained using T2-weighted imaging and standard diffusion imaging (via the apparent diffusion coefficient (ADC)). Experimental results suggest that correlated diffusion imaging provide improved delineation between healthy and cancerous tissue and may have potential as a diagnostic tool for cancer detection and localization in the prostate gland. A new form of diffusion magnetic resonance imaging called correlated diffusion imaging (CDI) was developed for the purpose of aiding radiologists in cancer detection and localization in the prostate gland. Preliminary results show CDI shows considerable promise as a diagnostic aid for radiologists in the detection and localization of prostate cancer

  17. Gaseous diffusion system

    International Nuclear Information System (INIS)

    Garrett, G.A.; Shacter, J.

    1978-01-01

    A gaseous diffusion system is described comprising a plurality of diffusers connected in cascade to form a series of stages, each of the diffusers having a porous partition dividing it into a high pressure chamber and a low pressure chamber, and means for combining a portion of the enriched gas from a succeeding stage with a portion of the enriched gas from the low pressure chamber of each stage and feeding it into one extremity of the high pressure chamber thereof

  18. Inverse diffusion theory of photoacoustics

    International Nuclear Information System (INIS)

    Bal, Guillaume; Uhlmann, Gunther

    2010-01-01

    This paper analyzes the reconstruction of diffusion and absorption parameters in an elliptic equation from knowledge of internal data. In the application of photoacoustics, the internal data are the amount of thermal energy deposited by high frequency radiation propagating inside a domain of interest. These data are obtained by solving an inverse wave equation, which is well studied in the literature. We show that knowledge of two internal data based on well-chosen boundary conditions uniquely determines two constitutive parameters in diffusion and Schrödinger equations. Stability of the reconstruction is guaranteed under additional geometric constraints of strict convexity. No geometric constraints are necessary when 2n internal data for well-chosen boundary conditions are available, where n is spatial dimension. The set of well-chosen boundary conditions is characterized in terms of appropriate complex geometrical optics solutions

  19. Diffusion in compacted betonite

    International Nuclear Information System (INIS)

    Muurinen, A.; Rantanen, J.

    1985-01-01

    The objective of this report is to collect the literature bearing on the diffusion in compacted betonite, which has been suggested as possible buffer material for the disposal of spent fuel. Diffusion in a porous, water-saturated material is usually described as diffusion in the pore-water where sorption on the solid matter can delay the migration in the instationary state. There are also models which take into consideration that the sorbed molecules can also move while being sorbed. Diffusion experiments in compacted bentonite have been reported by many authors. Gases, anions, cations and actinides have been used as diffusing molecules. The report collects the results and the information on the measurement methods. On the basis of the results can be concluded that different particles possibly follow different diffusion mechanisms. The parameters which affect the diffusion seem to be for example the size, the electric charge and the sorption properties of the diffusing molecule. The report also suggest the parameters to be used in the diffusion calculation of the safety analyses of spent fuel disposal. (author)

  20. Ensemble atmospheric dispersion modeling for emergency response consequence assessments

    International Nuclear Information System (INIS)

    Addis, R.P.; Buckley, R.L.

    2003-01-01

    Full text: Prognostic atmospheric dispersion models are used to generate consequence assessments, which assist decision-makers in the event of a release from a nuclear facility. Differences in the forecast wind fields generated by various meteorological agencies, differences in the transport and diffusion models themselves, as well as differences in the way these models treat the release source term, all may result in differences in the simulated plumes. This talk will address the U.S. participation in the European ENSEMBLE project, and present a perspective an how ensemble techniques may be used to enable atmospheric modelers to provide decision-makers with a more realistic understanding of how both the atmosphere and the models behave. Meteorological forecasts generated by numerical models from national and multinational meteorological agencies provide individual realizations of three-dimensional, time dependent atmospheric wind fields. These wind fields may be used to drive atmospheric dispersion (transport and diffusion) models, or they may be used to initiate other, finer resolution meteorological models, which in turn drive dispersion models. Many modeling agencies now utilize ensemble-modeling techniques to determine how sensitive the prognostic fields are to minor perturbations in the model parameters. However, the European Union programs RTMOD and ENSEMBLE are the first projects to utilize a WEB based ensemble approach to interpret the output from atmospheric dispersion models. The ensembles produced are different from those generated by meteorological forecasting centers in that they are ensembles of dispersion model outputs from many different atmospheric transport and diffusion models utilizing prognostic atmospheric fields from several different forecast centers. As such, they enable a decision-maker to consider the uncertainty in the plume transport and growth as a result of the differences in the forecast wind fields as well as the differences in the