Science.gov

Sample records for radiation diffuse radiation

  1. Diffuse radiation

    NASA Technical Reports Server (NTRS)

    1981-01-01

    A diffuse celestial radiation which is isotropic at least on a course scale were measured from the soft X-ray region to about 150 MeV, at which energy the intensity falls below that of the galactic emission for most galactic latitudes. The spectral shape, the intensity, and the established degree of isotropy of this diffuse radiation already place severe constraints on the possible explanations for this radiation. Among the extragalactic theories, the more promising explanations of the isotropic diffuse emission appear to be radiation from exceptional galaxies from matter antimatter annihilation at the boundaries of superclusters of galaxies of matter and antimatter in baryon symmetric big bang models. Other possible sources for extragalactic diffuse gamma radiation are discussed and include normal galaxies, clusters of galaxies, primordial cosmic rays interacting with intergalactic matter, primordial black holes, and cosmic ray leakage from galaxies.

  2. Adaptive multigroup radiation diffusion

    E-print Network

    Williams, Richard B., Sc. D. Massachusetts Institute of Technology

    2005-01-01

    This thesis describes the development and implementation of an algorithm for dramatically increasing the accuracy and reliability of multigroup radiation diffusion simulations at low group counts. This is achieved by ...

  3. Diffuse galactic radiation

    NASA Astrophysics Data System (ADS)

    Casandjian, Jean-Marc

    2012-12-01

    High-energy interstellar emission is produced by interactions of cosmic-ray electrons and nuclei with the interstellar medium and low-energy radiation fields in the Milky Way. This is not only a background for point-like and extended sources studies, but also a unique tool to learn about cosmic rays and the interstellar medium. Thanks to its energy range from 20 MeV to more than 300 GeV, its large effective area and field of view, its improved angular resolution, as well as an all-sky survey strategy, the Fermi Large Area Telescope (LAT) is the best instrument to study high-energy Galactic interstellar emission, which accounts for most of the photons it detects. To disentangle degeneracies in the GeV range, complementary observations are crucial at lower and higher energy, for example by INTEGRAL/SPI, CGRO/COMPTEL or HESS, as well as all-sky radio or sub-millimeter surveys. We provide an overview of the Galactic interstellar gamma-ray emission modeling and focus on ?-ray H I emissivity and large scale structures studies performed with the LAT.

  4. Diffuse Cosmic Infrared Background Radiation

    NASA Technical Reports Server (NTRS)

    Dwek, Eli

    2002-01-01

    The diffuse cosmic infrared background (CIB) consists of the cumulative radiant energy released in the processes of structure formation that have occurred since the decoupling of matter and radiation following the Big Bang. In this lecture I will review the observational data that provided the first detections and limits on the CIB, and the theoretical studies explaining the origin of this background. Finally, I will also discuss the relevance of this background to the universe as seen in high energy gamma-rays.

  5. Measurements of the diffuse ultraviolet radiation

    NASA Technical Reports Server (NTRS)

    Fix, John D.; Craven, John D.; Frank, Louis A.

    1989-01-01

    The imaging instrumentation on the Dynamics Explorer 1 satellite has been used to measure the intensity of the diffuse ultraviolet radiation on two great circles about the sky. It is found that the isotropic component of the diffuse ultraviolet radiation (possibly of extragalactic origin) has an intensity of 530 + or - 80 units (a unit is 1 photon per sq cm s A sr) at a wavelength of 150 nm. The Galactic component of the diffuse ultraviolet radiation has a dependence on Galactic latitude which requires strongly forward scattering particles if it is produced by dust above the Galactic plane.

  6. Diffuse ionizing radiation within HH jets

    SciTech Connect

    Esquivel, A.; Raga, A. C. E-mail: raga@nucleares.unam.mx

    2013-12-20

    We present numerical hydrodynamical simulations of a time-dependent ejection velocity precessing jet. The parameters used in our models correspond to a high excitation Herbig-Haro object, such as HH 80/81. We have included the transfer of ionizing radiation produced within the shocked regions of the jet. The radiative transfer is computed with a ray-tracing scheme from all the cells with an emissivity above a certain threshold. We show the development of a radiative precursor, and compare the morphology with a model without the diffuse radiation. Our simulations show that the morphology of the H? emission is affected considerably if the diffuse ionizing radiation is accounted for. The predicted H? position-velocity diagram (i.e., spatially resolved emission line profiles) from a model with the transfer of ionizing radiation has a relatively strong component at zero velocity, corresponding to the radiative precursor. Qualitatively similar 'zero velocity components' are observed in HH 80/81 and in the jet from Sanduleak's star in the Large Magellanic Cloud.

  7. Radiation

    Cancer.gov

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

  8. Assessment of diffuse radiation models in Azores

    NASA Astrophysics Data System (ADS)

    Magarreiro, Clarisse; Brito, Miguel; Soares, Pedro; Azevedo, Eduardo

    2014-05-01

    Measured irradiance databases usually consist of global solar radiation data with limited spatial coverage. Hence, solar radiation models have been developed to estimate the diffuse fraction from the measured global irradiation. This information is critical for the assessment of the potential of solar energy technologies; for example, the decision to use photovoltaic systems with tracking system. The different solar radiation models for this purpose differ on the parameters used as input. The simplest, and most common, are models which use global radiation information only. More sophisticated models require meteorological parameters such as information from clouds, atmospheric turbidity, temperature or precipitable water content. Most of these models comprise correlations with the clearness index, kt (portion of horizontal extra-terrestrial radiation reaching the Earth's surface) to obtain the diffuse fraction kd (portion of diffuse component from global radiation). The applicability of these different models is related to the local atmospheric conditions and its climatic characteristics. The models are not of general validity and can only be applicable to locations where the albedo of the surrounding terrain and the atmospheric contamination by dust are not significantly different from those where the corresponding methods were developed. Thus, models of diffuse fraction exhibit a relevant degree of location dependence: e.g. models developed considering data acquired in Europe are mainly linked to Northern, Central or, more recently, Mediterranean areas. The Azores Archipelago, with its particular climate and cloud cover characteristics, different from mainland Europe, has not yet been considered for the development of testing of such models. The Azorean climate reveals large amounts of cloud cover in its annual cycle, with spatial and temporal variabilities more complex than the common Summer/Winter pattern. This study explores the applicability of different existing correlation models of diffuse fraction and clearness index or other plain parameters to the Azorean region. Reliable data provided by the Atmospheric Radiation Measurements (ARM) Climate Research Facility from the Graciosa Island deployment of the ARM Mobile Facility (http://www.arm.gov/sites/amf/grw) was used to perform the analysis. Model results showed a tendency to underestimate higher values of diffuse radiation. From the performance results of the correlation models reviewed it was clear that there is room for improvement.

  9. The diffuse component of erythemal ultraviolet radiation.

    PubMed

    Silva, Abel A

    2015-10-28

    The diffuse (Dif) component of ultraviolet radiation (UVR) plays an important role in the daily exposure of humans to solar radiation. This study proposes a semi-empirical method to obtain the Dif component of the erythemal dose rate, or the erythemally weighted irradiance, (EDRDif) calculated from synchronized measurements of the Dif component of UVR (UVDif) and the global (G) irradiances of both UVR (UVG) and the erythemal dose rate (EDRG). Since the study was conducted in the tropics, results involve a wide range of solar zenith angles to which EDRDif is seasonally dependent. Clouds are the main atmospheric agent affecting Dif radiation. The ratio between Dif and G (Dif/G) showed a quadratic dependence on cloud cover with a coefficient of determination r(2) = 0.79. The maxima of EDRDif were mainly above the moderate range (>137.5 mW m(-2)) of the UV-Index and reached the extreme range (>262.5 mW m(-2)) for the spring-summer period. The fraction of the global daily erythemal dose (daily EDG) corresponding to Dif radiation (daily EDDif) ranged from 936 J m(-2) to 5053 J m(-2) and averaged 2673 J m(-2). Daily EDDif corresponded to at least 48% of daily EDG for a practically cloudless sky. Therefore, Dif radiation is a real threat. Lighter skin people (types I and II) can get sunburnt in a couple of minutes under such an incidence of radiation. Moreover, accumulative harm can affect all skin types. PMID:26313148

  10. Automatic actinometric system for diffuse radiation measurement

    NASA Astrophysics Data System (ADS)

    Litwiniuk, Agnieszka; Zajkowski, Maciej

    2015-09-01

    Actinometric station is using for measuring solar of radiation. The results are helpful in determining the optimal position of solar panels relative to the Sun, especially in today's world, when the energy coming from the Sun and other alternative sources of energy become more and more popular. Polish climate does not provide as much energy as in countries in southern Europe, but it is possible to increase the amount of energy produced by appropriate arrangement of photovoltaic panels. There is the possibility of forecasting the amount of produced energy, the cost-effectiveness and profitability of photovoltaic installations. This implies considerable development opportunities for domestic photovoltaic power plants. This article presents description of actinometric system for diffuse radiation measurement, which is equipped with pyranometer - thermopile temperature sensor, amplifier AD620, AD Converter ADS1110, microcontroller Atmega 16, SD card, GPS module and LCD screen.

  11. Adaptive Implicit Non-Equilibrium Radiation Diffusion

    SciTech Connect

    Philip, Bobby; Wang, Zhen; Berrill, Mark A; Rodriguez Rodriguez, Manuel; Pernice, Michael

    2013-01-01

    We describe methods for accurate and efficient long term time integra- tion of non-equilibrium radiation diffusion systems: implicit time integration for effi- cient long term time integration of stiff multiphysics systems, local control theory based step size control to minimize the required global number of time steps while control- ling accuracy, dynamic 3D adaptive mesh refinement (AMR) to minimize memory and computational costs, Jacobian Free Newton-Krylov methods on AMR grids for efficient nonlinear solution, and optimal multilevel preconditioner components that provide level independent solver convergence.

  12. Spectrometer system for diffuse extreme ultraviolet radiation

    NASA Technical Reports Server (NTRS)

    Labov, Simon E.

    1989-01-01

    A unique grazing incidence spectrometer system has been designed to study diffuse line emission between 80 and 650 A with 10-30 A resolution. The minimum detectable emission line strength during a 5-min observation ranges from 100-2000 ph/sq cm sec str. The instrument uses mechanically ruled reflection gratings placed in front of a linear array of mirrors. These mirrors focus the spectral image on microchannel plate detectors located behind thin filters. The field of view is 40 min of arc by 15 deg, and there is no spatial imaging. This instrument has been fabricated, calibrated, and successfully flown on a sounding rocket to observe the astronomical background radiation.

  13. Diffuse galactic annihilation radiation from supernova nucleosynthesis

    NASA Technical Reports Server (NTRS)

    Higdon, J. C.

    1985-01-01

    The propagation of MeV positrons in the outer ejecta of type I supernovae was investigated. It was found that the positrons created at times of approx 100 days propagated along magnetic field lines in the outer ejecta without any appreciable pitch-angle scattering or excitation of hydromagnetic waves. The lack of significant pitch-angle scattering is well consistent with models of wave excitation and scattering by resonant interactions. This occurs because time periods to scatter the particles or to excite waves are significantly longer than escape times. Thus it is expected that, when positrons are not coupled to the ejecta by Coulomb collisions, they escape from the relatively cold, dense ejecta and reside predominantly in the tenuous, hotter, shock-heated interstellar gas. In the tenuous shock-heated gas the positron lifetime against annihilation is much greater than lifetimes in the dense ejectra. Thus the production of steady-state diffuse annihilation radiation by some fraction of these escaped positrons seems probable.

  14. Discrete diffusion Monte Carlo for frequency-dependent radiative transfer

    SciTech Connect

    Densmore, Jeffrey D; Kelly, Thompson G; Urbatish, Todd J

    2010-11-17

    Discrete Diffusion Monte Carlo (DDMC) is a technique for increasing the efficiency of Implicit Monte Carlo radiative-transfer simulations. In this paper, we develop an extension of DDMC for frequency-dependent radiative transfer. We base our new DDMC method on a frequency-integrated diffusion equation for frequencies below a specified threshold. Above this threshold we employ standard Monte Carlo. With a frequency-dependent test problem, we confirm the increased efficiency of our new DDMC technique.

  15. Radiative Extinction of Gaseous Spherical Diffusion Flames in Microgravity

    NASA Technical Reports Server (NTRS)

    Santa, K. J.; Chao, B. H.; Sunderland, P. B.; Urban, D. L.; Stocker, D. P.; Axelbaum, R. L.

    2007-01-01

    Radiative extinction of spherical diffusion flames was investigated experimentally and numerically. The experiments involved microgravity spherical diffusion flames burning ethylene and propane at 0.98 bar. Both normal (fuel flowing into oxidizer) and inverse (oxidizer flowing into fuel) flames were studied, with nitrogen supplied to either the fuel or the oxygen. Flame conditions were chosen to ensure that the flames extinguished within the 2.2 s of available test time; thus extinction occurred during unsteady flame conditions. Diagnostics included color video and thin-filament pyrometry. The computations, which simulated flow from a porous sphere into a quiescent environment, included detailed chemistry, transport and radiation, and yielded transient results. Radiative extinction was observed experimentally and simulated numerically. Extinction time, peak temperature, and radiative loss fraction were found to be independent of flow rate except at very low flow rates. Radiative heat loss was dominated by the combustion products downstream of the flame and was found to scale with flame surface area, not volume. For large transient flames the heat release rate also scaled with surface area and thus the radiative loss fraction was largely independent of flow rate. Peak temperatures at extinction onset were about 1100 K, which is significantly lower than for kinetic extinction. One observation of this work is that while radiative heat losses can drive transient extinction, this is not because radiative losses are increasing with time (flame size) but rather because the heat release rate is falling off as the temperature drops.

  16. Theoretical and Numerical Investigation of Radiative Extinction of Diffusion Flames

    NASA Technical Reports Server (NTRS)

    Ray, Anjan

    1996-01-01

    The influence of soot radiation on diffusion flames was investigated using both analytical and numerical techniques. Soot generated in diffusion flames dominate the flame radiation over gaseous combustion products and can significantly lower the temperature of the flame. In low gravity situations there can be significant accumulation of soot and combustion products in the vicinity of the primary reaction zone owing to the absence of any convective buoyant flow. Such situations may result in substantial suppression of chemical activities in a flame, and the possibility of a radiative extinction may also be anticipated. The purpose of this work was to not only investigate the possibility of radiative extinction of a diffusion flame but also to qualitatively and quantitatively analyze the influence of soot radiation on a diffusion flame. In this study, first a hypothetical radiative loss profile of the form of a sech(sup 2) was assumed to influence a pure diffusion flame. It was observed that the reaction zone can, under certain circumstances, move through the radiative loss zone and locate itself on the fuel side of the loss zone contrary to our initial postulate. On increasing the intensity and/or width of the loss zone it was possible to extinguish the flame, and extinction plots were generated. In the presence of a convective flow, however, the movement of the temperature and reaction rate peaks indicated that the flame behavior is more complicated compared to a pure diffusional flame. A comprehensive model of soot formation, oxidation and radiation was used in a more involved analysis. The soot model of Syed, Stewart and Moss was used for soot nucleation and growth and the model of Nagle and Strickland-Constable was used for soot oxidation. The soot radiation was considered in the optically thin limit. An analysis of the flame structure revealed that the radiative loss term is countered both by the reaction term and the diffusion term. The essential balance for the soot volume fraction was found to be between the processes of soot convection and soot growth. Such a balance yielded to analytical treatment and the soot volume fraction could be expressed in the form of an integral. The integral was evaluated using two approximate methods and the results agreed very well with the numerical solutions for all cases examined.

  17. Lossy radial diffusion of relativistic Jovian electrons. [calculation of synchrotron radiation and electron radiation for Jupiter

    NASA Technical Reports Server (NTRS)

    Barbosa, D. D.; Coroniti, F. V.

    1976-01-01

    The radial diffusion equation with synchrotron losses was solved by the Laplace transform method for near-equatorially mirroring relativistic electrons. The evolution of a power law distribution function was found and the characteristics of synchrotron burn-off are stated in terms of explicit parameters for an arbitrary diffusion coefficient. Emissivity from the radiation belts of Jupiter was studied. Asymptotic forms for the distribution in the strong synchrotron loss regime are provided.

  18. Self-Similar Radiation-Hydrodynamics Solutions in the Equilibrium Diffusion Limit 

    E-print Network

    Lane, Taylor Kinsey

    2013-01-31

    This work presents semi-analytical solutions to a radiation-hydrodynamics problems of a radiation source driving an initially cold medium. Our solutions are in the equilibrium diffusion limit, include material motion and allow for radiation...

  19. Radiation enhanced diffusion of Nd in UO2

    NASA Astrophysics Data System (ADS)

    Han, Xiaochun; Heuser, Brent J.

    2015-11-01

    Single crystal UO2 thin films with Nd as tracer elements in the film mid-plane have been grown on yttria-stabilized zirconia (YSZ) substrates. The films were irradiated with 1.8 MeV Kr+ ions in the temperature range from 400 °C to 1113 °C, where an evident enhanced diffusion was found in UO2. The temperature dependent measurements have shown an activation energy of 0.56 ± 0.04 eV below 800 °C, and 1.9 ± 0.3 eV above 900 °C. The rate-dependent measurements have shown a linear dependence on the radiation flux, which indicates radiation enhanced diffusion (RED) is in the sink limited kinetics regime. Comparison of the RED results between UO2 and CeO2 has shown significant differences, which indicates that CeO2 used as UO2 surrogate may be questioned in terms of cation diffusion.

  20. Comparison of the Radiative Two-Flux and Diffusion Approximations

    NASA Technical Reports Server (NTRS)

    Spuckler, Charles M.

    2006-01-01

    Approximate solutions are sometimes used to determine the heat transfer and temperatures in a semitransparent material in which conduction and thermal radiation are acting. A comparison of the Milne-Eddington two-flux approximation and the diffusion approximation for combined conduction and radiation heat transfer in a ceramic material was preformed to determine the accuracy of the diffusion solution. A plane gray semitransparent layer without a substrate and a non-gray semitransparent plane layer on an opaque substrate were considered. For the plane gray layer the material is semitransparent for all wavelengths and the scattering and absorption coefficients do not vary with wavelength. For the non-gray plane layer the material is semitransparent with constant absorption and scattering coefficients up to a specified wavelength. At higher wavelengths the non-gray plane layer is assumed to be opaque. The layers are heated on one side and cooled on the other by diffuse radiation and convection. The scattering and absorption coefficients were varied. The error in the diffusion approximation compared to the Milne-Eddington two flux approximation was obtained as a function of scattering coefficient and absorption coefficient. The percent difference in interface temperatures and heat flux through the layer obtained using the Milne-Eddington two-flux and diffusion approximations are presented as a function of scattering coefficient and absorption coefficient. The largest errors occur for high scattering and low absorption except for the back surface temperature of the plane gray layer where the error is also larger at low scattering and low absorption. It is shown that the accuracy of the diffusion approximation can be improved for some scattering and absorption conditions if a reflectance obtained from a Kubelka-Munk type two flux theory is used instead of a reflection obtained from the Fresnel equation. The Kubelka-Munk reflectance accounts for surface reflection and radiation scattered back by internal scattering sites while the Fresnel reflection only accounts for surface reflections.

  1. Fires increase Amazon forest productivity through increases in diffuse radiation

    NASA Astrophysics Data System (ADS)

    Rap, A.; Spracklen, D. V.; Mercado, L.; Reddington, C. L.; Haywood, J. M.; Ellis, R. J.; Phillips, O. L.; Artaxo, P.; Bonal, D.; Restrepo Coupe, N.; Butt, N.

    2015-06-01

    Atmospheric aerosol scatters solar radiation increasing the fraction of diffuse radiation and the efficiency of photosynthesis. We quantify the impacts of biomass burning aerosol (BBA) on diffuse radiation and plant photosynthesis across Amazonia during 1998-2007. Evaluation against observed aerosol optical depth allows us to provide lower and upper BBA emissions estimates. BBA increases Amazon basin annual mean diffuse radiation by 3.4-6.8% and net primary production (NPP) by 1.4-2.8%, with quoted ranges driven by uncertainty in BBA emissions. The enhancement of Amazon basin NPP by 78-156 Tg C a-1 is equivalent to 33-65% of the annual regional carbon emissions from biomass burning. This NPP increase occurs during the dry season and acts to counteract some of the observed effect of drought on tropical production. We estimate that 30-60 Tg C a-1 of this NPP enhancement is within woody tissue, accounting for 8-16% of the observed carbon sink across mature Amazonian forests.

  2. Analytic expressions for ULF wave radiation belt radial diffusion coefficients

    PubMed Central

    Ozeke, Louis G; Mann, Ian R; Murphy, Kyle R; Jonathan Rae, I; Milling, David K

    2014-01-01

    We present analytic expressions for ULF wave-derived radiation belt radial diffusion coefficients, as a function of L and Kp, which can easily be incorporated into global radiation belt transport models. The diffusion coefficients are derived from statistical representations of ULF wave power, electric field power mapped from ground magnetometer data, and compressional magnetic field power from in situ measurements. We show that the overall electric and magnetic diffusion coefficients are to a good approximation both independent of energy. We present example 1-D radial diffusion results from simulations driven by CRRES-observed time-dependent energy spectra at the outer boundary, under the action of radial diffusion driven by the new ULF wave radial diffusion coefficients and with empirical chorus wave loss terms (as a function of energy, Kp and L). There is excellent agreement between the differential flux produced by the 1-D, Kp-driven, radial diffusion model and CRRES observations of differential electron flux at 0.976 MeV—even though the model does not include the effects of local internal acceleration sources. Our results highlight not only the importance of correct specification of radial diffusion coefficients for developing accurate models but also show significant promise for belt specification based on relatively simple models driven by solar wind parameters such as solar wind speed or geomagnetic indices such as Kp. Key Points Analytic expressions for the radial diffusion coefficients are presented The coefficients do not dependent on energy or wave m value The electric field diffusion coefficient dominates over the magnetic PMID:26167440

  3. Diffuse Radiation from the Aquila Rift

    E-print Network

    Jyothy, S N; Karuppath, Narayanankutty; Sujatha, N V

    2015-01-01

    We present an analysis of the diffuse ultraviolet (UV) background in a low latitude region near the Aquila Rift based on observations made by the Galaxy Evolution Explorer (GALEX). The UV background is at a level of about 2000 ph cm^-2 s^-1 sr^-1 \\AA^-1 with no correlation with either the Galactic latitude or the 100 micron infrared (IR) emission. Rather, the UV emission falls off with distance from the bright B2 star HIP 88149, which is in the centre of the field. We have used a Monte Carlo model to derive an albedo of 0.6 - 0.7 in the UV with a phase function asymmetry factor (g) of 0.2 - 0.4. The value for the albedo is dependent on the dust distribution while g is determined by the extent of the halo.

  4. Diffuse Radiation from the Aquila Rift

    NASA Astrophysics Data System (ADS)

    Jyothy, S. N.; Murthy, Jayant; Karuppath, Narayanankutty; Sujatha, N. V.

    2015-12-01

    We present an analysis of the diffuse ultraviolet (UV) background in a low latitude region near the Aquila Rift based on observations made by the Galaxy Evolution Explorer (GALEX). The UV background is at a level of about 2000 ph cm-2 s-1 sr-1 Å-1 with no correlation with either the Galactic latitude or the 100 ?m infrared (IR) emission. Rather, the UV emission falls off with distance from the bright B2 star HIP 88149, which is in the centre of the field. We have used a Monte Carlo model to derive an albedo of 0.6-0.7 in the UV with a phase function asymmetry factor (g) of 0.2-0.4. The value for the albedo is dependent on the dust distribution while g is determined by the extent of the halo.

  5. The origin of the diffuse background gamma-radiation

    NASA Technical Reports Server (NTRS)

    Stecker, F. W.; Puget, J. L.

    1974-01-01

    Recent observations have now provided evidence for diffuse background gamma radiation extending to energies beyond 100 MeV. There is some evidence of isotropy and implied cosmological origin. Significant features in the spectrum of this background radiation have been observed which provide evidence for its origin in nuclear processes in the early stages of the big-band cosmology and tie in these processes with galaxy fromation theory. A crucial test of the theory may lie in future observations of the background radiation in the 100 MeV to 100 GeV energy range which may be made with large orbiting spark-chamber satellite detectors. A discussion of the theoretical interpretations of present data, their connection with baryon symmetric cosmology and galaxy formation theory, and the need for future observations are given.

  6. The origin of the diffuse background gamma radiation

    NASA Technical Reports Server (NTRS)

    Stecker, F. W.; Puget, J. L.

    1974-01-01

    Recent observations provided evidence for diffuse background gamma radiation extending to energies beyond 100 MeV, and evidence of isotropy and implied cosmological origin. Significant features in the spectrum of this background radiation were observed which provide evidence for its origin in nuclear processes in the early stages of big-bang cosmology, and connect these processes with the galaxy formation theory. A test of the theory is in future observations of the background radiation in the 100 MeK to 100 GeV energy range which are made with large orbiting spark-chamber satellite detectors. The theoretical interpretations of present data, their connection with baryon-symmetric cosmology and galaxy formation theory, and the need for future observations are discussed.

  7. THE MYSTERY OF THE COSMIC DIFFUSE ULTRAVIOLET BACKGROUND RADIATION

    SciTech Connect

    Henry, Richard Conn; Murthy, Jayant; Overduin, James; Tyler, Joshua E-mail: jmurthy@yahoo.com E-mail: 97tyler@cardinalmail.cua.edu

    2015-01-01

    The diffuse cosmic background radiation in the Galaxy Evolution Explorer far-ultraviolet (FUV, 1300-1700 Å) is deduced to originate only partially in the dust-scattered radiation of FUV-emitting stars: the source of a substantial fraction of the FUV background radiation remains a mystery. The radiation is remarkably uniform at both far northern and far southern Galactic latitudes and increases toward lower Galactic latitudes at all Galactic longitudes. We examine speculation that this might be due to interaction of the dark matter with the nuclei of the interstellar medium, but we are unable to point to a plausible mechanism for an effective interaction. We also explore the possibility that we are seeing radiation from bright FUV-emitting stars scattering from a ''second population'' of interstellar grains—grains that are small compared with FUV wavelengths. Such grains are known to exist, and they scatter with very high albedo, with an isotropic scattering pattern. However, comparison with the observed distribution (deduced from their 100 ?m emission) of grains at high Galactic latitudes shows no correlation between the grains' location and the observed FUV emission. Our modeling of the FUV scattering by small grains also shows that there must be remarkably few such ''smaller'' grains at high Galactic latitudes, both north and south; this likely means simply that there is very little interstellar dust of any kind at the Galactic poles, in agreement with Perry and Johnston. We also review our limited knowledge of the cosmic diffuse background at ultraviolet wavelengths shortward of Ly?—it could be that our ''second component'' of the diffuse FUV background persists shortward of the Lyman limit and is the cause of the reionization of the universe.

  8. VOYAGER OBSERVATIONS OF THE DIFFUSE FAR-ULTRAVIOLET RADIATION FIELD

    SciTech Connect

    Murthy, Jayant; Henry, Richard Conn; Holberg, Jay B.

    2012-03-01

    The two Voyager spacecraft have completed their planetary exploration mission and are now probing the outer realms of the heliosphere. The Voyager ultraviolet spectrometers continued to operate well after the Voyager 2 Neptune encounter in 1989. We present a complete database of diffuse radiation observations made by both Voyagers: a total of 1943 spectra (500-1600 A) scattered throughout the sky. These include observations of dust-scattered starlight, emission lines from the hot interstellar medium, and a number of locations where no diffuse radiation was detected, with the very low upper limit of about 25 photons cm{sup -2} s{sup -1} sr{sup -1} A{sup -1}. Many of these observations were from late in the mission when there was significantly less contribution from interplanetary emission lines and thus less contamination of the interstellar signal.

  9. The diffusion approximation. An application to radiative transfer in clouds

    NASA Technical Reports Server (NTRS)

    Arduini, R. F.; Barkstrom, B. R.

    1976-01-01

    It is shown how the radiative transfer equation reduces to the diffusion equation. To keep the mathematics as simple as possible, the approximation is applied to a cylindrical cloud of radius R and height h. The diffusion equation separates in cylindrical coordinates and, in a sample calculation, the solution is evaluated for a range of cloud radii with cloud heights of 0.5 km and 1.0 km. The simplicity of the method and the speed with which solutions are obtained give it potential as a tool with which to study the effects of finite-sized clouds on the albedo of the earth-atmosphere system.

  10. Direct and diffuse solar-radiation exergy at the earth's surface

    SciTech Connect

    Badescu, V. )

    1992-04-01

    This paper presents relationships for the calculation of exergy of direct and diffuse solar radiation at the earth's surface. Application of these relationships requires a knowledge of direct and diffuse solar radiation fluxes at the earth's surface. Whereas the exergy of direct solar radiation is relatively independent of the atmospheric conditions, and is in excess of 85% of the internal energy, the exergy of diffuse radiation depends strongly on both the atmospheric conditions and the ambient temperature.

  11. Influence of radiation damage on xenon diffusion in silicon carbide

    NASA Astrophysics Data System (ADS)

    Friedland, E.; Gärtner, K.; Hlatshwayo, T. T.; van der Berg, N. G.; Thabethe, T. T.

    2014-08-01

    Diffusion of xenon in poly and single crystalline silicon carbide and the possible influence of radiation damage on it are investigated. For this purpose 360 keV xenon ions were implanted in commercial 6H-SiC and CVD-SiC wafers at room temperature, 350 °C and 600 °C. Width broadening of the implantation profiles and xenon retention during isochronal and isothermal annealing up to temperatures of 1500 °C was determined by RBS-analysis, whilst in the case of 6H-SiC damage profiles were simultaneously obtained by ?-particle channelling. No diffusion or xenon loss was detected in the initially amorphized and eventually recrystallized surface layer of cold implanted 6H-SiC during annealing up to 1200 °C. Above that temperature serious erosion of the implanted surface occurred, which made any analysis impossible. No diffusion or xenon loss is detected in the hot implanted 6H-SiC samples during annealing up to 1400 °C. Radiation damage dependent grain boundary diffusion is observed at 1300 °C in CVD-SiC.

  12. [Comparative observation of diffuse radiation in Qianyanzhou during the spring of 2012].

    PubMed

    Han, Jia-yin; Li, Sheng-gong; Zhang, Lei-ming; Wen, Xue-fa; Li, Qing-kang

    2015-03-01

    Global radiation and diffuse radiation were measured from March to June of 2012 in Qianyanzhou Experimental Station of Red Soil and Hilly Land, Chinese Academy of Sciences by ising three types of pyranometers, including CMP11 attached with a shadow ring, SPN1 and RSR3, which were placed in parallel. The observations showed that both global radiation and diffuse radiation measured by these pyranometers had a good linear correlation. The global radiation measured by SPN1 and RSR3 was respectively 3. 0% and 20.5% lower than that measured by the CMP 11. The diffuse radiation measured by SPN1 and RSR3. was respectively 5.5% and 7.9% lower of than that measured by the CMP11. Under the sunny, cloudy and overcast conditions, the daily variations of diffuse radiation measured by the three pyranometers were similar, and hence, the diffuse radiation values at a specific solar elevation angle measured by the different pyranometers were also similar. There was difference in daily accumulative diffuse radiation measured by the different pyranometers. Monthly diffuse fractions of March, April and May were 0.56, 0.59 and 0.70, respectively. In the subtropical area of southern China, the diffuse radiation accounted for a relatively large proportion of the global solar radiation and varied considerably over time. It is necessary to conduct long-term continuous measurements to capture the variability of diffuse radiation over different underlying surfaces. PMID:26288860

  13. Influence of radiation damage on krypton diffusion in silicon carbide

    NASA Astrophysics Data System (ADS)

    Friedland, E.; Hlatshwayo, T. T.; van der Berg, N. G.; Mabena, M. C.

    2015-07-01

    Diffusion of krypton in poly and single crystalline silicon carbide is investigated and compared with the previously obtained results for xenon, which pointed to a different diffusion mechanism than observed for chemically active elements. For this purpose 360 keV krypton ions were implanted in commercial 6H-SiC and CVD-SiC wafers at room temperature, 350 °C and 600 °C. Width broadening of the implantation profiles and krypton retention during isochronal and isothermal annealing up to temperatures of 1400 °C was determined by RBS-analysis, whilst in the case of 6H-SiC damage profiles were simultaneously obtained by ?-particle channeling. Little diffusion and no krypton loss was detected in the initially amorphized and eventually recrystallized surface layer of cold implanted 6H-SiC during annealing up to 1200 °C. Above that temperature thermal etching of the implanted surface became increasingly important. No diffusion or krypton loss is detected in the hot implanted 6H-SiC samples during annealing up to 1400 °C. Radiation damage dependent grain boundary diffusion is observed at 1300 °C in CVD-SiC. The results seem to indicate, that the chemically inert noble gas atoms do not form defect-impurity complexes, which strongly influence the diffusion behavior of other diffusors in silicon carbide.

  14. The Gamma-ray galactic diffuse radiation and Cerenkov telescopes

    SciTech Connect

    Chardonnet, P.; Salati, P.; Silk, J.; Grenier, I.; Smoot, G.

    1995-12-01

    By using the PYTHIA version of the Lund Monte Carlo program, we study the photon yield of proton-proton collisions in the energy range between 10 GeV and 1 TeV. The resulting photon spectrum turns out to scale roughly with incident energy. Then, by folding the energy spectrum of cosmic-ray protons with the distribution of HI and CO, the Galactic diffuse emission of {gamma}-rays above 100 GeV is mapped. Prospects for observing that diffuse radiation with atmospheric Cerenkov telescopes are discussed. Present instruments are able to detect the {gamma}-ray glow of the Galactic center. The latter will be mapped by the next generation of telescopes if their energy threshold is decreased. However, a detailed survey of the Galactic ridge will be a real challenge, even in the long term. The MILAGRO project seems more appropriate. Finally, we investigate the {gamma}-ray emission from weakly interacting massive particles clustering at the Galactic center. It has been speculated that those species are a major component of the halo dark matter. We show that their {gamma}-ray signal is swamped in the Galactic diffuse radiation and cannot be observed at TeV energies. {copyright} {ital 1995 The American Astronomical Society.}

  15. A Coupled Model for Radiative Transfer: Doppler Effects, Equilibrium and Non-Equilibrium Diffusion Asymptotics

    E-print Network

    Goudon, Thierry

    A Coupled Model for Radiative Transfer: Doppler Effects, Equilibrium and Non-Equilibrium Diffusion. The interaction terms take into account both scattering and absorption/emission phenomena, as well as Doppler-diffusion equations. Key words. Hydrodynamic limits. Diffusion approximation. Radiative transfer. Doppler correction

  16. Diffusive vs. impulsive energetic electron transport during radiation belt storms

    NASA Astrophysics Data System (ADS)

    Vassiliadis, D.; Koepke, M.; Tornquist, M.

    2008-12-01

    Earth's electron radiation belts are continually replenished by inward particle transport (as well as other, local acceleration processes) taking place during radiation belt storms. For some storms the radial transport is primarily diffusive while for others it is impulsive, or characterized by injections. To distinguish between these types of inward transport, we first use a dynamic model of the phase-space density as measured by POLAR/HIST and expressed in terms of adiabatic invariants [Green and Kivelson, 2004]. In a review of storms from 1997 to 2004 the coefficients of the model are peaked at characteristic temporal and phase- space (mu, k, L*) scales during specific storms. The transport is quantified in terms of those invariants which are violated and identified with peaks of the electron distribution in invariant space. Second, we run guiding- center simulations in wave fields fitted to in situ measurements complemented at low and high L by ground ULF pulsations. The modes of response identified in earlier studies from SAMPEX and POLAR electron flux measurements are now associated with primarily diffusive transport in the central range of the outer belt, L=4-8, and primarily impulsive transport near the plasmapause boundary, L=3-4.

  17. Computing the monthly mean daily diffuse radiation from clearness index and percent possible sunshine

    SciTech Connect

    Gopinathan, K.K. )

    1988-01-01

    There are many locations where no measured data on diffuse radiation are available and have to be estimated from empirical correlations. Here were develop correlations for predicting monthly mean daily diffuse radiation on a horizontal surface, for locations in India, from the measured data of clearness index and percent possible sunshine. Three models are developed from the experimental data of three stations in India and the applicability of the developed equations are tested by estimating monthly mean daily diffuse radiation for four locations. A correlation connecting monthly mean daily diffuse radiation together with the cleaners index and percent possible sunshine is found to be the most accurate one for Indian locations.

  18. Soot and Radiation Measurements in Microgravity Jet Diffusion Flames

    NASA Technical Reports Server (NTRS)

    Ku, Jerry C.

    1996-01-01

    The subject of soot formation and radiation heat transfer in microgravity jet diffusion flames is important not only for the understanding of fundamental transport processes involved but also for providing findings relevant to spacecraft fire safety and soot emissions and radiant heat loads of combustors used in air-breathing propulsion systems. Our objectives are to measure and model soot volume fraction, temperature, and radiative heat fluxes in microgravity jet diffusion flames. For this four-year project, we have successfully completed three tasks, which have resulted in new research methodologies and original results. First is the implementation of a thermophoretic soot sampling technique for measuring particle size and aggregate morphology in drop-tower and other reduced gravity experiments. In those laminar flames studied, we found that microgravity soot aggregates typically consist of more primary particles and primary particles are larger in size than those under normal gravity. Comparisons based on data obtained from limited samples show that the soot aggregate's fractal dimension varies within +/- 20% of its typical value of 1.75, with no clear trends between normal and reduced gravity conditions. Second is the development and implementation of a new imaging absorption technique. By properly expanding and spatially-filtering the laser beam to image the flame absorption on a CCD camera and applying numerical smoothing procedures, this technique is capable of measuring instantaneous full-field soot volume fractions. Results from this technique have shown the significant differences in local soot volume fraction, smoking point, and flame shape between normal and reduced gravity flames. We observed that some laminar flames become open-tipped and smoking under microgravity. The third task we completed is the development of a computer program which integrates and couples flame structure, soot formation, and flame radiation analyses together. We found good agreements between model predictions and experimental data for laminar and turbulent flames under both normal and reduced gravity. We have also tested in the laboratory the techniques of rapid-insertion fine-wire thermocouples and emission pyrometry for temperature measurements. These techniques as well as laser Doppler velocimetry and spectral radiative intensity measurement have been proposed to provide valuable data and improve the modeling analyses.

  19. Verification of SpacePy's radial diffusion radiation belt model

    NASA Astrophysics Data System (ADS)

    Welling, D. T.; Koller, J.; Camporeale, E.

    2011-09-01

    Model verification, or the process of ensuring that the prescribed equations are properly solved, is a necessary step in code development. Careful, quantitative verification guides users when selecting grid resolution and time step and gives confidence to code developers that existing code is properly instituted. This work introduces the RadBelt radiation belt model, a new, open-source version of the Dynamic Radiation Environment Assimilation Model (DREAM) and uses the Method of Manufactured Solutions (MMS) to quantitatively verify it. Order of convergence is investigated for a plethora of code configurations and source terms. The ability to apply many different diffusion coefficients, including time constant and time varying, is thoroughly investigated. The model passes all of the tests, demonstrating correct implementation of the numerical solver. The importance of DLL and source term dynamics on the selection of time step and grid size is also explored. Finally, an alternative method to apply the source term is examined to illustrate additional considerations required when non-linear source terms are used.

  20. Verification of SpacePy's radial diffusion radiation belt model

    NASA Astrophysics Data System (ADS)

    Welling, D. T.; Koller, J.; Camporeale, E.

    2012-03-01

    Model verification, or the process of ensuring that the prescribed equations are properly solved, is a necessary step in code development. Careful, quantitative verification guides users when selecting grid resolution and time step and gives confidence to code developers that existing code is properly instituted. This work introduces the RadBelt radiation belt model, a new, open-source version of the Dynamic Radiation Environment Assimilation Model (DREAM) and uses the Method of Manufactured Solutions (MMS) to quantitatively verify it. Order of convergence is investigated for a plethora of code configurations and source terms. The ability to apply many different diffusion coefficients, including time constant and time varying, is thoroughly investigated. The model passes all of the tests, demonstrating correct implementation of the numerical solver. The importance of DLL and source term dynamics on the selection of time step and grid size is also explored. Finally, an alternative method to apply the source term is examined to illustrate additional considerations required when non-linear source terms are used.

  1. Newton-Krylov methods applied to nonequilibrium radiation diffusion

    SciTech Connect

    Knoll, D.A.; Rider, W.J.; Olsen, G.L.

    1998-03-10

    The authors present results of applying a matrix-free Newton-Krylov method to a nonequilibrium radiation diffusion problem. Here, there is no use of operator splitting, and Newton`s method is used to convert the nonlinearities within a time step. Since the nonlinear residual is formed, it is used to monitor convergence. It is demonstrated that a simple Picard-based linearization produces a sufficient preconditioning matrix for the Krylov method, thus elevating the need to form or store a Jacobian matrix for Newton`s method. They discuss the possibility that the Newton-Krylov approach may allow larger time steps, without loss of accuracy, as compared to an operator split approach where nonlinearities are not converged within a time step.

  2. Influence of Diffused Solar Radiation on the Solar Concentrating System of a Plant Shoot Configuration

    NASA Astrophysics Data System (ADS)

    Obara, Shin'ya

    Investigation of a plant shoot configuration is used to obtain valuable information concerning the received light system. Additionally, analysis results concerning a plant shoot configuration interaction with direct solar radiation were taken from a past study. However, in order to consider a plant shoot as a received sunlight system, it is necessary to understand the received light characteristics of both direct solar radiation and diffused solar radiation. Under a clear sky, the ratio of direct solar radiation to diffused solar radiation is large. However, under a clouded sky, the amount of diffused solar radiation becomes larger. Therefore, in this paper, we investigate the received light characteristics of a plant shoot configuration under the influence of diffused solar radiation. As a result, we clarify the relationship between the amount of diffused solar radiation and the amount of received light as a function of the characteristics of the plant shoot configuration. In order to obtain diffused solar radiation, it is necessary to correspond to the radiation of the multi-directions. In the analysis, the characteristic of the difference in arrangement of the top leaf and the other leaf was obtained. Therefore, in analysis, leaves other than the top were distributed in the wide range.

  3. Step-by-Step Simulation of Radiation of Radiation Chemistry Using Green Functions for Diffusion-Influenced Reactions

    NASA Technical Reports Server (NTRS)

    Plante, Ianik; Cucinotta, Francis A.

    2011-01-01

    The irradiation of biological systems leads to the formation of radiolytic species such as H(raised dot), (raised dot)OH, H2, H2O2, e(sup -)(sub aq), etc.[1]. These species react with neighboring molecules, which result in damage in biological molecules such as DNA. Radiation chemistry is there for every important to understand the radiobiological consequences of radiation[2]. In this work, we discuss an approach based on the exact Green Functions for diffusion-influenced reactions which may be used to simulate radiation chemistry and eventually extended to study more complex systems, including DNA.

  4. Increased diffuse radiation fraction does not significantly accelerate plant growth

    NASA Astrophysics Data System (ADS)

    Angert, Alon; Krakauer, Nir

    2010-05-01

    A recent modelling study (Mercado et al., 2009) claims that increased numbers of scattering aerosols are responsible for a substantial fraction of the terrestrial carbon sink in recent decades because higher diffuse light fraction enhances plant net primary production (NPP). Here we show that observations of atmospheric CO2 seasonal cycle and tree ring data indicate that the relation between diffuse light and NPP is actually quite weak on annual timescales. The inconsistency of these data with the modelling results may arise because the relationships used to quantify the enhancement of NPP were calibrated with eddy covariance measurements of hourly carbon uptake. The effect of diffuse-light fraction on carbon uptake could depend on timescale, since this effect varies rapidly as sun angle and cloudiness change, and since plants can respond dynamically over various timescales to change in incoming radiation. Volcanic eruptions, such as the eruption of Mount Pinatubo in 1991, provide the best available tests for the effect of an annual-scale increase in the diffuse light fraction. Following the Pinatubo Eruption, in 1992 and 1993, a sharp decrease in the atmospheric CO2 growth rate was observed. This could have resulted from enhanced plant carbon uptake. Mercado et al. (2009) argue that largely as a result of the (volcanic aerosol driven) increase in diffuse light fraction, NPP was elevated in 1992, particularly between 25° N-45° N where annual NPP was modelled to be ~0.8 PgC (~10%) above average. In a previous study (Angert et al., 2004) a biogeochemical model (CASA) linked to an atmospheric tracer model (MATCH), was used to show that a diffuse-radiation driven increase in NPP in the extratropics will enhance carbon uptake mostly in summer, leading to a lower CO2 seasonal minimum. Here we use a 'toy model' to show that this conclusion is general and model-independent. The model shows that an enhanced sink of 0.8 PgC, similar to that modelled by Mercado et al. (2009), will result in a measurable decrease (~0.6ppm) in the seasonal CO2 minimum. This holds regardless of whether the sink is the result of 1) An increase in NPP, or 2) The combined effect of a temperature-driven decrease in heterotrophic respiration (Rh) and no change in NPP. This is since both NPP and Rh peak in summer. By contrast, observations from the NOAA global CO2 monitoring network show the opposite change in the seasonal minimum in 1992 and 1993 (~0.2ppm increase) both at Mauna Loa, and in the Marine Boundary Layer mean (>20° N), which is hard to reconcile with increased NPP in northern summer. Another indicator of annual NPP is tree wood increment. Previous work (Krakauer et al., 2003) showed that the average response in tree ring series after past Pinatubo-size volcanic eruptions implied lower NPP north of 45° N, presumably as a result of shorter growing season and lower total irradiance induced by scattering aerosols, and no significant change in NPP at lower latitudes. Here we show that In 1992, after the Pinatubo eruption, ring width in the 25° N-45° N band was 99.3±2.9% of average (n=351 sites), similar to the average of 100.4±2.2% over past eruptions (n=15 eruptions) (Uncertainty is given as 2 SE.). These results are also inconsistent with substantial NPP enhancement, although a limitation of the tree-ring approach is that available measurements do not uniformly sample the latitude band. The combined evidence of tree rings and the CO2 seasonal cycle shows that the enhancement of NPP by scattering aerosols on annual timescales is weak. This result suggests that reducing aerosols through stricter pollution controls may strengthen the land carbon sink, while geo-engineering schemes which aim to mitigate global warming by spreading scattering aerosols in the stratosphere may weaken it.

  5. Effects of Refractive Index and Diffuse or Specular Boundaries on a Radiating Isothermal Layer

    NASA Technical Reports Server (NTRS)

    Siegel, R.; Spuckler, C. M.

    1994-01-01

    Equilibrium temperatures of an absorbing-emitting layer were obtained for exposure to incident radiation and with the layer boundaries either specular or diffuse. For high refractive indices the surface condition can influence the radiative heat balance if the layer optical thickness is small. Hence for a spectrally varying absorption coefficient the layer temperature is affected if there is significant radiative energy in the spectral range with a small absorption coefficient. Similar behavior was obtained for transient radiative cooling of a layer where the results are affected by the initial temperature and hence the fraction of energy radiated in the short wavelength region where the absorption coefficient is small. The results are a layer without internal scattering. If internal scattering is significant, the radiation reaching the internal surface of a boundary is diffused and the effect of the two different surface conditions would become small.

  6. An improved multipyranometer array for the measurement of direct and diffuse solar radiation 

    E-print Network

    Munger, Bryce Kirtley

    1997-01-01

    This thesis describes the development of an improved multipyranometer array (NDA) for the continuous remote measurement of direct and diff-use solar radiation. The NWA described in this thesis is an improvement over previously published MPA studies...

  7. Detailed modeling analysis for soot formation and radiation in microgravity gas jet diffusion flames

    NASA Technical Reports Server (NTRS)

    Ku, Jerry C.; Tong, LI; Greenberg, Paul S.

    1995-01-01

    Radiation heat transfer in combustion systems has been receiving increasing interest. In the case of hydrocarbon fuels, a significant portion of the radiation comes from soot particles, justifying the need for detailed soot formation model and radiation transfer calculations. For laminar gas jet diffusion flames, results from this project (4/1/91 8/22/95) and another NASA study show that flame shape, soot concentration, and radiation heat fluxes are substantially different under microgravity conditions. Our emphasis is on including detailed soot transport models and a detailed solution for radiation heat transfer, and on coupling them with the flame structure calculations. In this paper, we will discuss the following three specific areas: (1) Comparing two existing soot formation models, and identifying possible improvements; (2) A simple yet reasonably accurate approach to calculating total radiative properties and/or fluxes over the spectral range; and (3) Investigating the convergence of iterations between the flame structure solver and the radiation heat transfer solver.

  8. Data From HANE-Generated Radiation Belts and the Origin of Diffusion Theory

    SciTech Connect

    Winske, Dan

    2012-07-16

    In this presentation we briefly review some of the published data regarding the artificial radiation belts produced by the Starfish and R2 high altitude nuclear explosions in 1962. The data showed slow temporal variations of the belts in altitude (L) and pitch angle ({alpha}) that could be modeled as a diffusion process. That early work formed the basis for more complex radiation belt diffusion models that are in use at present.

  9. A hybrid transport-diffusion model for radiative transfer in absorbing and scattering media

    SciTech Connect

    Roger, M.; Caliot, C.; Crouseilles, N.; Coelho, P.J.

    2014-10-15

    A new multi-scale hybrid transport-diffusion model for radiative transfer is proposed in order to improve the efficiency of the calculations close to the diffusive regime, in absorbing and strongly scattering media. In this model, the radiative intensity is decomposed into a macroscopic component calculated by the diffusion equation, and a mesoscopic component. The transport equation for the mesoscopic component allows to correct the estimation of the diffusion equation, and then to obtain the solution of the linear radiative transfer equation. In this work, results are presented for stationary and transient radiative transfer cases, in examples which concern solar concentrated and optical tomography applications. The Monte Carlo and the discrete-ordinate methods are used to solve the mesoscopic equation. It is shown that the multi-scale model allows to improve the efficiency of the calculations when the medium is close to the diffusive regime. The proposed model is a good alternative for radiative transfer at the intermediate regime where the macroscopic diffusion equation is not accurate enough and the radiative transfer equation requires too much computational effort.

  10. Diffusion model of radiation transfer based on disperse media for CFB boilers

    SciTech Connect

    Liqun, M.; Wanqing, H.; Hanping, C.; Ziping, T.; Mingchuan, Z.

    1999-07-01

    This paper studies the effect of disperse media on radiation heat transfer in circulating fluidized bed. Because the concentration of particles is large in circulation fluidized bed, the absorbing, emitting, scattering property of particle must be considered comprehensively. In this article, diffusion model of radiation transport equation is built. By solving the coupled momentum equation, energy equation, and radiation transfer, the heat exchange law of fluidized bed with high concentration disperse media is investigated. From simulating the different optical properties of particle, diffusion model is proved to be convenient to be applied in industry-scale circulating fluidized bed boilers.

  11. Diffuse radiation increases global ecosystem-level water-use efficiency

    NASA Astrophysics Data System (ADS)

    Moffat, A. M.; Reichstein, M.; Cescatti, A.; Knohl, A.; Zaehle, S.

    2012-12-01

    Current environmental changes lead not only to rising atmospheric CO2 levels and air temperature but also to changes in air pollution and thus the light quality of the solar radiation reaching the land-surface. While rising CO2 levels are thought to enhance photosynthesis and closure of stomata, thus leading to relative water savings, the effect of diffuse radiation on transpiration by plants is less clear. It has been speculated that the stimulation of photosynthesis by increased levels of diffuse light may be counteracted by higher transpiration and consequently water depletion and drought stress. Ultimately, in water co-limited systems, the overall effect of diffuse radiation will depend on the sensitivity of canopy transpiration versus photosynthesis to diffuse light, i.e. whether water-use efficiency changes with relative levels of diffuse light. Our study shows that water-use efficiency increases significantly with higher fractions of diffuse light. It uses the ecosystem-atmosphere gas-exchange observations obtained with the eddy covariance method at 29 flux tower sites. In contrast to previous global studies, the analysis is based directly on measurements of diffuse radiation. Its effect on water-use efficiency was derived by analyzing the multivariate response of carbon and water fluxes to radiation and air humidity using a purely empirical approach based on artificial neural networks. We infer that per unit change of diffuse fraction the water-use efficiency increases up to 40% depending on diffuse fraction levels and ecosystem type. Hence, in regions with increasing diffuse radiation positive effects on primary production are expected even under conditions where water is co-limiting productivity.

  12. Ultra-low-frequency wave-driven diffusion of radiation belt relativistic electrons.

    PubMed

    Su, Zhenpeng; Zhu, Hui; Xiao, Fuliang; Zong, Q-G; Zhou, X-Z; Zheng, Huinan; Wang, Yuming; Wang, Shui; Hao, Y-X; Gao, Zhonglei; He, Zhaoguo; Baker, D N; Spence, H E; Reeves, G D; Blake, J B; Wygant, J R

    2015-01-01

    Van Allen radiation belts are typically two zones of energetic particles encircling the Earth separated by the slot region. How the outer radiation belt electrons are accelerated to relativistic energies remains an unanswered question. Recent studies have presented compelling evidence for the local acceleration by very-low-frequency (VLF) chorus waves. However, there has been a competing theory to the local acceleration, radial diffusion by ultra-low-frequency (ULF) waves, whose importance has not yet been determined definitively. Here we report a unique radiation belt event with intense ULF waves but no detectable VLF chorus waves. Our results demonstrate that the ULF waves moved the inner edge of the outer radiation belt earthward 0.3 Earth radii and enhanced the relativistic electron fluxes by up to one order of magnitude near the slot region within about 10?h, providing strong evidence for the radial diffusion of radiation belt relativistic electrons. PMID:26690250

  13. A multigrid Newton-Krylov method for flux-limited radiation diffusion

    SciTech Connect

    Rider, W.J.; Knoll, D.A.; Olson, G.L.

    1998-09-01

    The authors focus on the integration of radiation diffusion including flux-limited diffusion coefficients. The nonlinear integration is accomplished with a Newton-Krylov method preconditioned with a multigrid Picard linearization of the governing equations. They investigate the efficiency of the linear and nonlinear iterative techniques.

  14. Microstructural Evolution and Radiation Effects of Uranium-Bearing Diffusion Couples 

    E-print Network

    Wei, Chao-Chen

    2014-12-12

    of this dissertation is to unravel the radiation effects in microstructural and kinetic data. In order to achieve this, two major diffusion systems are chosen. For the first system, we start with two uranium-free diffusion couples to study Microstructural evolution...

  15. Modeling inward diffusion and slow decay of energetic electrons in the Earth's outer radiation belt

    NASA Astrophysics Data System (ADS)

    Ma, Q.; Li, W.; Thorne, R. M.; Ni, B.; Kletzing, C. A.; Kurth, W. S.; Hospodarsky, G. B.; Reeves, G. D.; Henderson, M. G.; Spence, H. E.; Baker, D. N.; Blake, J. B.; Fennell, J. F.; Claudepierre, S. G.; Angelopoulos, V.

    2015-02-01

    A new 3-D diffusion code is used to investigate the inward intrusion and slow decay of energetic radiation belt electrons (>0.5 MeV) observed by the Van Allen Probes during a 10 day quiet period on March 2013. During the inward transport, the peak differential electron fluxes decreased by approximately an order of magnitude at various energies. Our 3-D radiation belt simulation including radial diffusion and pitch angle and energy diffusion by plasmaspheric hiss and electromagnetic ion cyclotron (EMIC) waves reproduces the essential features of the observed electron flux evolution. The decay time scales and the pitch angle distributions in our simulation are consistent with the Van Allen Probe observations over multiple energy channels. Our study suggests that the quiet time energetic electron dynamics are effectively controlled by inward radial diffusion and pitch angle scattering due to a combination of plasmaspheric hiss and EMIC waves in the Earth's radiation belts.

  16. Estimation of the diffuse fraction of daily and monthly average global radiation for Fudhaliyah, Baghdad (Iraq)

    SciTech Connect

    Al-Hamdani, N.; Al-Riahi, M.; Tahir, K. )

    1989-01-01

    Separating the global solar radiation on a horizontal surface into direct and diffuse components is required in the simulation of solar energy systems. Many models have been developed for this purpose. The aim of this study is to establish, from the data collected over the period 1985-1986 at Fudhaliyah, daily correlations between (i) diffuse fraction of global radiation and clearness index; (ii) diffuse fraction and fractional sunshine duration; (iii) diffuse fraction and clearness index combined with fractional sunshine duration. In addition, the monthly average values of the above-mentioned correlations were established. Comparison with the most commonly used equation, Page's correlation, gives good agreement for monthly average of the relationship between diffuse fraction and clearness index. An equation for daily diffuse transmissivity values that incorporates a single physically based coefficient, which reflects the maximum clear-sky transmissivity at the study site is presented.

  17. Disentangling leaf area and environmental effects on the response of the net ecosystem CO2 exchange to diffuse radiation

    PubMed Central

    Wohlfahrt, Georg; Hammerle, Albin; Haslwanter, Alois; Bahn, Michael; Tappeiner, Ulrike; Cernusca, Alexander

    2013-01-01

    There is an ongoing discussion about why the net ecosystem CO2 exchange (NEE) of some ecosystems is less sensitive to diffuse radiation than others and about the role other environmental factors play in determining the response of NEE to diffuse radiation. Using a six-year data set from a temperate mountain grassland in Austria we show that differences between ecosystems may be reconciled based on their green area index (GAI; square meter green plant area per square meter ground area) - the sensitivity to diffuse radiation increasing with GAI. Our data suggest diffuse radiation to have a negligible influence on NEE below a GAI of 2 m2 m?2. Changes in air/soil temperature and air humidity concurrent with the fraction of diffuse radiation were found to amplify the sensitivity of the investigated temperate mountain grassland ecosystem to diffuse radiation. PMID:24347740

  18. Radiation Basics

    MedlinePLUS

    EPA United States Environmental Protection Agency Search Search Radiation Protection Share Facebook Twitter Google+ Pinterest Contact Us ... are here: EPA Home » Radiation Protection » Radiation Basics Radiation Basics Radiation is energy. It can come from ...

  19. Radiative diffusivity factors in cirrus and stratocumulus clouds: Application to two-stream models

    NASA Technical Reports Server (NTRS)

    Stephens, Graeme L.; Flatau, P. J.; Tsay, S.-C.; Hein, Paul F.

    1990-01-01

    A diffusion-like description of radiative transfer in clouds and the free atmosphere is often used. The two stream model is probably the best known example of such a description. The main idea behind the approach is that only the first few moments of radiance are needed to describe the radiative field correctly. Integration smooths details of the angular distribution of specific intensity and it is assumed that the closure parameters of the theory (diffusivity factors) are only weakly dependent on the distribution. The diffusivity factors are investigated using the results obtained from both Stratocumulus and Cirrus phases of FIRE experiment. A new theoretical framework is described in which two (upwards and downwards) diffusivity factors are used and a detailed multistream model is used to provide further insight about both the diffusivity factors and their dependence on scattering properties of clouds.

  20. Estimation of hourly global and diffuse solar radiation from hourly sunshine duration

    SciTech Connect

    Gopinathan, K.K )

    1992-01-01

    A statistical procedure has been employed to develop correlations of monthly-mean-hourly global and diffuse solar radiation on a horizontal surface to hourly sunshine duration. Several years of measured data on solar radiation and sunshine duration, reported in the literature for two stations in the southern African region, is employed for this purpose. The applicability of the developed correlations is tested by estimating solar radiation for a new location. The excellent agreement between the measured and estimated data for that station the wide applicability of the method.

  1. Effect of microwave radiation on diffusion behavior of anti-solvent during crystallization

    NASA Astrophysics Data System (ADS)

    Asakuma, Yusuke; Miura, Masataka

    2014-09-01

    The effect of microwave radiation on anti-solvent crystallization was investigated by in situ observation of nanoparticle size in a reactor. The precipitation of sodium chloride by the addition of ethanol was accelerated by the increase in molecular diffusion caused by microwave radiation. The microwave power controlled the particle size because increasing the power increases the temperature, which leads to the dissolution of the precipitate. The salt concentration in the solution, and the anti-solvent concentration and volume were important factors in anti-solvent crystallization under microwave radiation.

  2. Diffuse and direct components of solar radiation in ground-based and satellite-derived data

    NASA Astrophysics Data System (ADS)

    Liley, J. Ben

    2013-05-01

    Many applications of solar radiation data require values for the separate diffuse (F) and direct (R) components of global radiation (G). Accurate measurement of these has been difficult, and beyond the scope of many meteorological and climate networks. Here I describe the use of high-quality data from a Baseline Surface Radiation Network (BSRN) site to assess and enhance the quality and utility of surface irradiance data, whether measured by ground-based networks or inferred from satellite data. Prediction of R and F from measured G is shown to be consistent from timescales of one minute to one hour, and accuracy is adequate for practical use in solar energy applications.

  3. Radiation Protection

    MedlinePLUS

    EPA United States Environmental Protection Agency Search Search Radiation Protection Share Facebook Twitter Google+ Pinterest Contact Us Radiation Protection Document Library View and download EPA radiation ...

  4. A scheme for radiation pressure and photon diffusion with the M1 closure in RAMSES-RT

    NASA Astrophysics Data System (ADS)

    Rosdahl, J.; Teyssier, R.

    2015-06-01

    We describe and test an updated version of radiation-hydrodynamics in the RAMSES code, that includes three new features: (i) radiation pressure on gas, (ii) accurate treatment of radiation diffusion in an unresolved optically thick medium, and (iii) relativistic corrections that account for Doppler effects and work done by the radiation to first order in v/c. We validate the implementation in a series of tests, which include a morphological assessment of the M1 closure for the Eddington tensor in an astronomically relevant setting, dust absorption in an optically semithick medium, direct pressure on gas from ionizing radiation, convergence of our radiation diffusion scheme towards resolved optical depths, correct diffusion of a radiation flash and a constant luminosity radiation, and finally, an experiment from Davis et al. of the competition between gravity and radiation pressure in a dusty atmosphere, and the formation of radiative Rayleigh-Taylor instabilities. With the new features, RAMSES-RT can be used for state-of-the-art simulations of radiation feedback from first principles, on galactic and cosmological scales, including not only direct radiation pressure from ionizing photons, but also indirect pressure via dust from multiscattered IR photons reprocessed from higher-energy radiation, both in the optically thin and thick limits.

  5. Terahertz radiation from InAs induced by carrier diffusion and drift

    SciTech Connect

    Liu, Kai; Xu, Jingzhou; Yuan, Tao; Zhang, X.-C.

    2006-04-15

    Terahertz (THz) radiation from a (100) oriented InAs surfaces is dominated by the photo-Dember effect. The strength of the radiation is influenced by screening the radiation with doped carriers. When irradiated by femtosecond pulses, the wafer with the lowest doping concentration radiates THz power nearly two orders higher than the wafer with highest doping concentration. With identical optical excitation and same doping concentration, a p-type InAs generates stronger THz waves than an n-type InAs due to the weaker screening effect. The low doping p-type InAs (1x10{sup 16} cm{sup -3}) sample is the strongest THz wave emitter among all the unbiased semiconductors we have ever tested with a Ti:sapphire laser oscillator. The drift-diffusion equation (DDE) is used in the study of carrier drift and diffusion as well as subsequent THz radiation from InAs wafers. The calculation explains well the experimental observation of the relationship between a THz electric field and the doping properties of InAs. The physical pictures of the carrier drift and diffusion characteristics in InAs surfaces are also clearly provided in this report.

  6. An Experimental and Theoretical Study of Radiative Extinction of Diffusion Flames

    NASA Technical Reports Server (NTRS)

    Atreya, Arvind

    1995-01-01

    The objective of this research was to experimentally and theoretically investigate the radiation-induced extinction of gaseous diffusion flames in microgravity. The microgravity conditions were required because radiation-induced extinction is generally not possible in 1-g but is highly likely in microgravity. In 1-g, the flame-generated particulates (e.g. soot) and gaseous combustion products that are responsible for flame radiation, are swept away from the high temperature reaction zone by the buoyancy-induced flow and a steady state is developed. In microgravity, however, the absence of buoyancy-induced flow which transports the fuel and the oxidizer to the combustion zone and removes the hot combustion products from it enhances the flame radiation due to: (1) transient build-up of the combustion products in the flame zone which increases the gas radiation, and (2) longer residence time makes conditions appropriate for substantial amounts of soot to form which is usually responsible for most of the radiative heat loss. Numerical calculations conducted during the course of this work show that even non-radiative flames continue to become "weaker" (diminished burning rate per unit flame area) due to reduced rates of convective and diffusive transport. Thus, it was anticipated that radiative heat loss may eventually extinguish the already "weak" microgravity diffusion flame. While this hypothesis appears convincing and our numerical calculations support it, experiments for a long enough microgravity time could not be conducted during the course of this research to provide an experimental proof. Space shuttle experiments on candle flames show that in an infinite ambient atmosphere, the hemispherical candle flame in microgravity will burn indefinitely. It was hoped that radiative extinction can be experimentally shown by the aerodynamically stabilized gaseous diffusion flames where the fuel supply rate was externally controlled. While substantial progress toward this goal was made during this project, identifying the experimental conditions for which radiative extinction occurs for various fuels requires further study. Details concerning this research which are discussed in published articles are included in the appendices.

  7. Moisture Diffusivity Characteristics of Rough Rice Under Infrared Radiation Heating

    Technology Transfer Automated Retrieval System (TEKTRAN)

    To design an efficient infrared (IR) dryer for rough rice, it is important to understand the drying behavior of rice grains under infrared heating. The objective of this study was to determine the moisture diffusivity and moisture diffusivity coefficient of rough rice under IR heating and cooling. ...

  8. Secondary production of neutral pi-mesons and the diffuse galactic gamma radiation

    NASA Technical Reports Server (NTRS)

    Dermer, C. D.

    1986-01-01

    Isobaric and scaling model predictions of the secondary spectra of neutral pi-mesons produced in proton-proton collisions, at energies between threshold and a few GeV, are compared on the basis of accelerator data and found to show the isobaric model to be superior. This model is accordingly used, in conjuction with a scaling model representation at high energies, in a recalculation of the pi exp (0) gamma-radiation's contribution to the diffuse galactic gamma background; the cosmic ray-induced production of photons (whose energy exceeds 100 MeV) by such radiation occurs at a rate of 1.53 x 10 to the -25 photons/(s-H atom). These results are compared with previous calculations of this process as well as with COS-B observations of the diffuse galactic gamma-radiation.

  9. Diffuse optical tomography using the one-way radiative transfer equation.

    PubMed

    González-Rodríguez, Pedro; Kim, Arnold D

    2015-06-01

    We present a computational study of diffuse optical tomography using the one-way radiative transfer equation. The one-way radiative transfer is a simplification of the radiative transfer equation to approximate the transmission of light through tissues. The major simplification of this approximation is that the intensity satisfies an initial value problem rather than a boundary value problem. Consequently, the inverse problem to reconstruct the absorption and scattering coefficients from transmission measurements of scattered light is simplified. Using the initial value problem for the one-way radiative transfer equation to compute the forward model, we are able to quantitatively reconstruct the absorption and scattering coefficients efficiently and effectively for simple problems and obtain reasonable results for complicated problems. PMID:26114025

  10. Radiation enteritis

    MedlinePLUS

    Radiation enteropathy; Radiation-induced small bowel injury; Post-radiation enteritis ... Radiation therapy uses high-powered x-rays, particles, or radioactive seeds to kill cancer cells. The therapy ...

  11. Radiation Therapy

    MedlinePLUS

    ... Professionals Questions to Ask about Your Treatment Research Radiation Therapy Radiation therapy (also called radiotherapy) is a ... rays of your teeth or broken bones. How Radiation Therapy Works against Cancer At high doses, radiation ...

  12. Absorption and scattering of laser radiation by the diffusion flame of aviation kerosene

    SciTech Connect

    Gvozdev, S V; Glova, A F; Dubrovskii, V Yu; Durmanov, S T; Krasyukov, A G; Lysikov, A Yu; Smirnov, G V; Solomakhin, V B

    2012-04-30

    The absorption coefficient of the radiation of a repetitively pulsed Nd : YAG laser with an average output power up to 6 W and of a cw ytterbium optical fibre laser with an output power up to 3 kW was measured in the diffusion flame of aviation kerosene burning on a free surface in the atmospheric air. The absorption coefficient as a function of flame length, radiation power, and radiation intensity, which was varied in the {approx}10{sup 3} - 5 Multiplication-Sign 10{sup 4} W cm{sup -2} range, was obtained for two distances (1 and 2 cm) between the laser beam axis and the surface. The coefficient of radiation absorption by kerosene flame was compared with that in ethanol and kerosene - ethanol mixture flames. The radiation power scattered by a small segment of the kerosene flame irradiated by Nd : YAG laser radiation was measured as a function of longitudinal and azimuthal coordinates. An estimate was made of the total scattered radiation power.

  13. Using a Simple Apparatus to Measure Direct and Diffuse Photosynthetically Active Radiation at Remote Locations

    PubMed Central

    Cruse, Michael J.; Kucharik, Christopher J.; Norman, John M.

    2015-01-01

    Plant canopy interception of photosynthetically active radiation (PAR) drives carbon dioxide (CO2), water and energy cycling in the soil-plant-atmosphere system. Quantifying intercepted PAR requires accurate measurements of total incident PAR above canopies and direct beam and diffuse PAR components. While some regional data sets include these data, e.g. from Atmospheric Radiation Measurement (ARM) Program sites, they are not often applicable to local research sites because of the variable nature (spatial and temporal) of environmental variables that influence incoming PAR. Currently available instrumentation that measures diffuse and direct beam radiation separately can be cost prohibitive and require frequent adjustments. Alternatively, generalized empirical relationships that relate atmospheric variables and radiation components can be used but require assumptions that increase the potential for error. Our goal here was to construct and test a cheaper, highly portable instrument alternative that could be used at remote field sites to measure total, diffuse and direct beam PAR for extended time periods without supervision. The apparatus tested here uses a fabricated, solar powered rotating shadowband and other commercially available parts to collect continuous hourly PAR data. Measurements of total incident PAR had nearly a one-to-one relationship with total incident radiation measurements taken at the same research site by an unobstructed point quantum sensor. Additionally, measurements of diffuse PAR compared favorably with modeled estimates from previously published data, but displayed significant differences that were attributed to the important influence of rapidly changing local environmental conditions. The cost of the system is about 50% less than comparable commercially available systems that require periodic, but not continual adjustments. Overall, the data produced using this apparatus indicates that this instrumentation has the potential to support ecological research via a relatively inexpensive method to collect continuous measurements of total, direct beam and diffuse PAR in remote locations. PMID:25668208

  14. Modeling Earth's Outer Radiation Belt Electron Dynamics---Radial Diffusion, Heating, and Loss

    NASA Astrophysics Data System (ADS)

    Tu, Weichao

    Earth's outer radiation belt is a relativistic electron environment that is hazardous to space systems. It is characterized by large variations in the electron flux, which are controlled by the competition between source, transport, and loss processes. One of the central questions in outer radiation belt research is to resolve the relative contribution of radial diffusion, wave heating, and loss to the enhancement and decay of the radiation belt electrons. This thesis studies them together and separately. Firstly, we develop an empirical Fokker-Planck model that includes radial diffusion, an internal source, and finite electron lifetimes parameterized as functions of geomagnetic indices. By simulating the observed electron variations, the model suggests that the required magnitudes of radial diffusion and internal heating for the enhancement of energetic electrons in the outer radiation belt vary from storm to storm, and generally internal heating contributes more to the enhancements of MeV energy electrons at L=4 (L is approximately the radial distance in Earth radii at the equator). However, since the source, transport, and loss terms in the model are empirical, the model results have uncertainties. To eliminate the uncertainty in the loss rate, both the precipitation and the adiabatic loss of radiation belt electrons are quantitatively studied. Based on the observations from Solar Anomalous and Magnetospheric Particle Explorer (SAMPEX), a Drift-Diffusion model is applied to quantify electron precipitation loss, which is the dominant non-adiabatic loss mechanism for electrons in the heart of the outer radiation belt. Model results for a small storm, a moderate storm, and an intense storm indicate that fast precipitation losses of relativistic electrons, on the time scale of hours, persistently occur in the storm main phases and with more efficient losses at higher energies over wide range of L regions. Additionally, calculations of adiabatic effects on radiation belt electrons at low altitudes demonstrate that the adiabatic flux drop of electrons during the storm main phase is both altitude and storm dependent. During the main phase of a moderate geomagnetic storm, due solely to adiabatic effects a satellite at low altitude sees either zero electron flux or a fractional flux drop depending on its altitude. To physically quantify the radial diffusion rate, we use power spectral density and global mode structure of the Ultra-Low-Frequency (ULF) waves, which are derived from the Lyon-Fedder-Mobarry (LFM) MHD simulation and validated by field data from real satellites. The calculated total diffusion rate is shown to be dominated by the contribution from magnetic field perturbations, and much less from the electric field. Fast diffusion generally occurs when solar wind dynamic pressure is high or nightside geomagnetic activity is strong and with higher diffusion rates at higher L regions. Work performed in this thesis provides realistic loss rate and radial diffusion rate of radiation belt electrons, as well as a comprehensive Fokker-Planck model that can take the loss and radial diffusion rates as inputs and then determine the internal heating rate with less uncertainty. By this approach, we will be able to quantitatively understand the relative contribution of radial diffusion, wave heating, and loss to the variations of radiation belt electrons.

  15. Multifrequency radiation diffusion equations for homogeneous, refractive, lossy media and their interface conditions

    SciTech Connect

    Shestakov, Aleksei I.

    2013-06-15

    We derive time-dependent multifrequency diffusion equations for homogeneous, refractive lossy media. The equations are applicable for a domain composed of several materials with distinct refractive indexes. In such applications, the fundamental radiation variable, the intensity I, is discontinuous across material interfaces. The diffusion equations evolve a variable ?, the integral of I over all directions divided by the square of the refractive index. Attention is focused on boundary and internal interface conditions for ?. For numerical solutions using finite elements, it is shown that at material interfaces, the usual diffusion coefficient 1/3? of the multifrequency equation, where ? is the opacity, is modified by a tensor diffusion term consisting of integrals of the reflectivity. Numerical results are presented. For a single material simulation, the ? equations yield the same result as diffusion equations that evolve the spectral radiation energy density. A second simulation solves a test problem that models radiation transport in a domain comprised of materials with different refractive indexes. Results qualitatively agree with those previously published.

  16. Using hybrid implicit Monte Carlo diffusion to simulate gray radiation hydrodynamics

    NASA Astrophysics Data System (ADS)

    Cleveland, Mathew A.; Gentile, Nick

    2015-06-01

    This work describes how to couple a hybrid Implicit Monte Carlo Diffusion (HIMCD) method with a Lagrangian hydrodynamics code to evaluate the coupled radiation hydrodynamics equations. This HIMCD method dynamically applies Implicit Monte Carlo Diffusion (IMD) [1] to regions of a problem that are opaque and diffusive while applying standard Implicit Monte Carlo (IMC) [2] to regions where the diffusion approximation is invalid. We show that this method significantly improves the computational efficiency as compared to a standard IMC/Hydrodynamics solver, when optically thick diffusive material is present, while maintaining accuracy. Two test cases are used to demonstrate the accuracy and performance of HIMCD as compared to IMC and IMD. The first is the Lowrie semi-analytic diffusive shock [3]. The second is a simple test case where the source radiation streams through optically thin material and heats a thick diffusive region of material causing it to rapidly expand. We found that HIMCD proves to be accurate, robust, and computationally efficient for these test problems.

  17. Moisture diffusivity of rough rice under infrared radiation drying

    Technology Transfer Automated Retrieval System (TEKTRAN)

    To design efficient infrared (IR) dryers for rough rice, it is important to understand the drying behavior of rough rice under IR heating. The objective of this study was to determine the moisture diffusivity of rough rice under IR heating followed by cooling. The effects of initial moisture content...

  18. Equations and Algorithms for Mixed Frame Flux-Limited Diffusion Radiation Hydrodynamics

    E-print Network

    Mark R. Krumholz; Richard I. Klein; Christopher F. McKee; John Bolstad

    2007-05-28

    We analyze the mixed frame equations of radiation hydrodynamics under the approximations of flux-limited diffusion and a thermal radiation field, and derive the minimal set of evolution equations that includes all terms that are of leading order in any regime of non-relativistic radiation hydrodynamics. Our equations are accurate to first order in v/c in the static diffusion regime. In contrast, we show that previous lower order derivations of these equations omit leading terms in at least some regimes. In comparison to comoving frame formulations of radiation hydrodynamics, our equations have the advantage that they manifestly conserve total energy, making them very well-suited to numerical simulations, particularly with adaptive meshes. For systems in the static diffusion regime, our analysis also suggests an algorithm that is both simpler and faster than earlier comoving frame methods. We implement this algorithm in the Orion adaptive mesh refinement code, and show that it performs well in a range of test problems.

  19. Uncertainty in assessment of radiation-induced diffusion index changes in individual patients

    NASA Astrophysics Data System (ADS)

    Nazem-Zadeh, Mohammad-Reza; Chapman, Christopher H.; Lawrence, Theodore S.; Tsien, Christina I.; Cao, Yue

    2013-06-01

    The purpose of this study is to evaluate repeatability coefficients of diffusion tensor indices to assess whether longitudinal changes in diffusion indices were true changes beyond the uncertainty for individual patients undergoing radiation therapy (RT). Twenty-two patients who had low-grade or benign tumors and were treated by partial brain radiation therapy (PBRT) participated in an IRB-approved MRI protocol. The diffusion tensor images in the patients were acquired pre-RT, week 3 during RT, at the end of RT, and 1, 6, and 18 months after RT. As a measure of uncertainty, repeatability coefficients (RC) of diffusion indices in the segmented cingulum, corpus callosum, and fornix were estimated by using test-retest diffusion tensor datasets from the National Biomedical Imaging Archive (NBIA) database. The upper and lower limits of the 95% confidence interval of the estimated RC from the test and retest data were used to evaluate whether the longitudinal percentage changes in diffusion indices in the segmented structures in the individual patients were beyond the uncertainty and thus could be considered as true radiation-induced changes. Diffusion indices in different white matter structures showed different uncertainty ranges. The estimated RC for fractional anisotropy (FA) ranged from 5.3% to 9.6%, for mean diffusivity (MD) from 2.2% to 6.8%, for axial diffusivity (AD) from 2.4% to 5.5%, and for radial diffusivity (RD) from 2.9% to 9.7%. Overall, 23% of the patients treated by RT had FA changes, 44% had MD changes, 50% had AD changes, and 50% had RD changes beyond the uncertainty ranges. In the fornix, 85.7% and 100% of the patients showed changes beyond the uncertainty range at 6 and 18 months after RT, demonstrating that radiation has a pronounced late effect on the fornix compared to other segmented structures. It is critical to determine reliability of a change observed in an individual patient for clinical decision making. Assessments of the repeatability and confidence interval of diffusion tensor measurements in white matter structures allow us to determine the true longitudinal change in individual patients.

  20. Radiation Heat Transfer Between Diffuse-Gray Surfaces Using Higher Order Finite Elements

    NASA Technical Reports Server (NTRS)

    Gould, Dana C.

    2000-01-01

    This paper presents recent work on developing methods for analyzing radiation heat transfer between diffuse-gray surfaces using p-version finite elements. The work was motivated by a thermal analysis of a High Speed Civil Transport (HSCT) wing structure which showed the importance of radiation heat transfer throughout the structure. The analysis also showed that refining the finite element mesh to accurately capture the temperature distribution on the internal structure led to very large meshes with unacceptably long execution times. Traditional methods for calculating surface-to-surface radiation are based on assumptions that are not appropriate for p-version finite elements. Two methods for determining internal radiation heat transfer are developed for one and two-dimensional p-version finite elements. In the first method, higher-order elements are divided into a number of sub-elements. Traditional methods are used to determine radiation heat flux along each sub-element and then mapped back to the parent element. In the second method, the radiation heat transfer equations are numerically integrated over the higher-order element. Comparisons with analytical solutions show that the integration scheme is generally more accurate than the sub-element method. Comparison to results from traditional finite elements shows that significant reduction in the number of elements in the mesh is possible using higher-order (p-version) finite elements.

  1. Radial diffusion models of energetic electrons and Jupiter's synchrotron radiation. I - Steady state solution

    NASA Technical Reports Server (NTRS)

    De Pater, Imke; Goertz, Christoph K.

    1990-01-01

    The results of a computer code modeling of the radial diffusion of equatorially confined energetic electrons in Jupiter's inner magnetosphere are compared with spacecraft as well as ground-based radio (synchrotron radiation) data. It is found that the synchrotron radiation spectrum cannot be reproduced without a significant hardening of the electron spectrum between L = 3 and L = 1.5. This hardening may be due to energy degradation by Jupiter's ring particles. The calculations also suggest that there may be larger-sized material outside Jupiter's ring up to L of about 4 or Io's orbit.

  2. Electromagnetic Radiation in Hot QCD Matter: Rates, Electric Conductivity, Flavor Susceptibility and Diffusion

    E-print Network

    Chang-Hwan Lee; Ismail Zahed

    2014-03-07

    We discuss the general features of the electromagnetic radiation from a thermal hadronic gas as constrained by chiral symmetry. The medium effects on the electromagnetic spectral functions and the partial restoration of chiral symmetry are quantified in terms of the pion densities. The results are compared with the electromagnetic radiation from a strongly interacting quark-gluon plasma in terms of the leading gluon condensate operators. We use the spectral functions as constrained by the emission rates to estimate the electric conductivity, the light flavor susceptibility and diffusion constant across the transition from the correlated hadronic gas to a strongly interacting quark-gluon plasma.

  3. Accurately specifying storm-time ULF wave radial diffusion in the radiation belts

    E-print Network

    Dimitrakoudis, Stavros; Balasis, Georgios; Papadimitriou, Constantinos; Anastasiadis, Anastasios; Daglis, Ioannis A

    2015-01-01

    Ultra-low frequency (ULF) waves can contribute to the transport, acceleration and loss of electrons in the radiation belts through inward and outward diffusion. However, the most appropriate parameters to use to specify the ULF wave diffusion rates are unknown. Empirical representations of diffusion coefficients often use Kp; however, specifications using ULF wave power offer an improved physics-based approach. We use 11 years of ground-based magnetometer array measurements to statistically parameterise the ULF wave power with Kp, solar wind speed, solar wind dynamic pressure and Dst. We find Kp is the best single parameter to specify the statistical ULF wave power driving radial diffusion. Significantly, remarkable high energy tails exist in the ULF wave power distributions when expressed as a function of Dst. Two parameter ULF wave power specifications using Dst as well as Kp provide a better statistical representation of storm-time radial diffusion than any single variable alone.

  4. Evaluating Contextual Processing in Diffusion MRI: Application to Optic Radiation Reconstruction for Epilepsy Surgery

    PubMed Central

    Tax, Chantal M. W.; Duits, Remco; Vilanova, Anna; ter Haar Romeny, Bart M.; Hofman, Paul; Wagner, Louis; Leemans, Alexander; Ossenblok, Pauly

    2014-01-01

    Diffusion MRI and tractography allow for investigation of the architectural configuration of white matter in vivo, offering new avenues for applications like presurgical planning. Despite the promising outlook, there are many pitfalls that complicate its use for (clinical) application. Amongst these are inaccuracies in the geometry of the diffusion profiles on which tractography is based, and poor alignment with neighboring profiles. Recently developed contextual processing techniques, including enhancement and well-posed geometric sharpening, have shown to result in sharper and better aligned diffusion profiles. However, the research that has been conducted up to now is mainly of theoretical nature, and so far these techniques have only been evaluated by visual inspection of the diffusion profiles. In this work, the method is evaluated in a clinically relevant application: the reconstruction of the optic radiation for epilepsy surgery. For this evaluation we have developed a framework in which we incorporate a novel scoring procedure for individual pathways. We demonstrate that, using enhancement and sharpening, the extraction of an anatomically plausible reconstruction of the optic radiation from a large amount of probabilistic pathways is greatly improved in three healthy controls, where currently used methods fail to do so. Furthermore, challenging reconstructions of the optic radiation in three epilepsy surgery candidates with extensive brain lesions demonstrate that it is beneficial to integrate these methods in surgical planning. PMID:25077946

  5. Temperature and Radiative Heat Flux Measurements in Microgravity Jet Diffusion Flames

    NASA Technical Reports Server (NTRS)

    Ku, Jerry C.; Greenberg, Paul S.

    1997-01-01

    The objective of this project is to provide detailed measurements and modeling analyses of local soot concentration, temperature and radiation heat flux distributions in laminar and turbulent jet diffusion flames under normal (1-g) and reduced gravity (0-g) conditions. Results published to date by these co-PI's and their co-workers include: 1. thermophoretic sampling and size and morphological analyses of soot aggregates in laminar flames under normal and reduced gravity conditions; 2. full-field absorption imaging for soot volume fraction maps in laminar and turbulent flames under normal and reduced gravity conditions; 3. an accurate solver module for detailed radiation heat transfer in nongray nonhomogeneous media; 4. a complete model to include flame structure, soot formation and an energy equation to couple with radiation solver.

  6. Diffusion and Radiation in Magnetized Collisionless Plasmas with High-Frequency Small-Scale Turbulence

    E-print Network

    Keenan, Brett D

    2015-01-01

    Magnetized high-energy-density plasmas can often have strong electromagnetic fluctuations whose correlation scale is smaller than the electron Larmor radius. Radiation from the electrons in such plasmas, which markedly differs from both synchrotron and cyclotron radiation, and their energy and pitch-angle diffusion are tightly related. In this paper, we present a comprehensive theoretical and numerical study of the particles' transport in both cold, "small-scale" Langmuir and Whistler-mode turbulence and its relation to the spectra of radiation simultaneously produced by these particles. We emphasize that this relation is a superb diagnostic tool of laboratory, astrophysical, interplanetary, and solar plasmas with a mean magnetic field and strong small-scale turbulence.

  7. Generation of Z mode radiation by diffuse auroral electron precipitation

    NASA Technical Reports Server (NTRS)

    Dusenbery, P. B.; Lyons, L. R.

    1985-01-01

    The generation of Z mode waves by diffuse auroral electron precipitation is investigated assuming that a loss cone exists in the upgoing portion of the distribution due to electron interactions with the atmosphere. The waves are generated at frequencies above, but very near, the local electron cyclotron frequency omega(e) and at wave normal angles larger than 90 deg. In agreement with Hewitt et al. (1983), the group velocity is directed downward in regions where the ratio of the upper hybrid frequency omega(pe) to Omega(e) is less than 0.5, so that Z mode waves excited above a satellite propagate toward it and away from the upper hybrid resonance. Z mode waves are excited in a frequency band between Omega(e) and about 1.02 Omega(e), and with maximum growth rates of about 0.001 Omega(e). The amplification length is about 100 km, which allows Z mode waves to grow to the intensities observed by high-altitude satellites.

  8. Step-by-Step Simulation of Radiation Chemistry Using Green Functions for Diffusion-Influenced Reactions

    NASA Technical Reports Server (NTRS)

    Plante, Ianik; Cucinotta, Francis A.

    2011-01-01

    Radiolytic species are formed approximately 1 ps after the passage of ionizing radiation through matter. After their formation, they diffuse and chemically react with other radiolytic species and neighboring biological molecules, leading to various oxidative damage. Therefore, the simulation of radiation chemistry is of considerable importance to understand how radiolytic species damage biological molecules [1]. The step-by-step simulation of chemical reactions is difficult, because the radiolytic species are distributed non-homogeneously in the medium. Consequently, computational approaches based on Green functions for diffusion-influenced reactions should be used [2]. Recently, Green functions for more complex type of reactions have been published [3-4]. We have developed exact random variate generators of these Green functions [5], which will allow us to use them in radiation chemistry codes. Moreover, simulating chemistry using the Green functions is which is computationally very demanding, because the probabilities of reactions between each pair of particles should be evaluated at each timestep [2]. This kind of problem is well adapted for General Purpose Graphic Processing Units (GPGPU), which can handle a large number of similar calculations simultaneously. These new developments will allow us to include more complex reactions in chemistry codes, and to improve the calculation time. This code should be of importance to link radiation track structure simulations and DNA damage models.

  9. The grand unified photon spectrum: A coherent view of the diffuse extragalactic background radiation

    NASA Technical Reports Server (NTRS)

    Ressell, M. Ted; Turner, Michael S.

    1989-01-01

    The spectrum of diffuse extragalactic background radiation (DEBRA) at wavelengths from 10(exp 5) to 10(exp -24) cm is presented in a coherent fashion. Each wavelength region, from the radio to ultra-high energy photons and cosmic rays, is treated both separately and as part of the grand unified photon spectrum (GUPS). A discussion of, and references to, the relevant literature for each wavelength region is included. This review should provide a useful tool for those interested in diffuse backgrounds, the epoch of galaxy formation, astrophysical/cosmological constraints to particle properties, exotic early Universe processes, and many other astrophysical and cosmological enterprises. As a worked example, researchers derive the cosmological constraints to an unstable-neutrino spies (with arbitrary branching ratio to a radiative decay mode) that follow from the GUPS.

  10. Asymptotic diffusion limit of cell temperature discretisation schemes for thermal radiation transport

    NASA Astrophysics Data System (ADS)

    Smedley-Stevenson, Richard P.; McClarren, Ryan G.

    2015-04-01

    This paper attempts to unify the asymptotic diffusion limit analysis of thermal radiation transport schemes, for a linear-discontinuous representation of the material temperature reconstructed from cell centred temperature unknowns, in a process known as 'source tilting'. The asymptotic limits of both Monte Carlo (continuous in space) and deterministic approaches (based on linear-discontinuous finite elements) for solving the transport equation are investigated in slab geometry. The resulting discrete diffusion equations are found to have nonphysical terms that are proportional to any cell-edge discontinuity in the temperature representation. Based on this analysis it is possible to design accurate schemes for representing the material temperature, for coupling thermal radiation transport codes to a cell centred representation of internal energy favoured by ALE (arbitrary Lagrange-Eulerian) hydrodynamics schemes.

  11. Solar UV-B in tropical forest gaps: Analysis using direct and diffuse radiation

    SciTech Connect

    Flint, S.D.; Caldwell, M.M.

    1995-06-01

    Experiments with natural levels of solar ultraviolet-B radiation (UV-B) have recently shown inhibition of the growth of some tropical forest tree seedlings. A knowledge of forest radiation environments is needed to help assess UV-B effects in natural situations. Although forest canopies strongly attenuate solar radiation, treefall gaps provide a very different radiation environment. We simultaneously measured both UV-B and photosynthetically active radiation (PAR) in forest gaps on Barro Colorado Island, Panama. Outside the forest, UV-B is predominately diffuse even under clear sky conditions. In sunflecks of small forest gaps, most of the UV-B was in the direct beam component. Compared to conditions outside the forest, the UV-B in these sunflecks was low relative to PAR. Shaded portions of the gap, in contrast, had proportionately high levels of UV-B relative to PAR. There are indications in the literature that relatively low UV-B levels may be effective under low PFD. Seasonal trends of PAR and UV-B in different locations in gaps can be inferred from hemispherical canopy photographs.

  12. The dependence on solar elevation of the correlation between monthly average hourly diffuse and global radiation

    SciTech Connect

    Soler, A. )

    1988-01-01

    In the present work, the dependence on {anti {gamma}} of the correlation between {anti K}{sub d} = {anti I}{sub d}/{anti I}{sub O} and {anti K}{sub t} = {anti I}/{anti I}{sub o} is studied, {anti I}, {anti I}{sub d}, and {anti I}{sub o} respectively being the monthly average hourly values of the global, diffuse, and extraterrestrial radiation, all of them on a horizontal surface, and {anti {gamma}} the solar elevation at midhour. The dependence is studied for Uccle for the following sky conditions. Condition A: clear skies (fraction of possible sunshine = 1) and the maximum values of direct radiation measured during the period considered (each of the hours before or after the solar noon for which radiation is received); Condition B corresponding to all the values of radiation measured when the sunshine fraction is 1 during the period considered; Condition C; corresponding to all the data collected, independently of the state of the sky; Condition D: corresponding to overcast skies ({anti I} = {anti I}{sub d}). From the available values of {anti I} and {anti I}{sub d} (monthly average hourly direct radiation on a horizontal surface), values of {anti K}{sub d} and {anti K}{sub t} for 5{degree} {le} {anti {gamma}} {le} 45{degree} and {Delta} {anti {gamma}} = 5{degree} are calculated using Newton's divided difference interpolation formula.

  13. Antibacterial properties of Au doped polycarbonate synthesized by gamma radiation assisted diffusion method

    NASA Astrophysics Data System (ADS)

    Hareesh, K.; Deore, Avinash V.; Dahiwale, S. S.; Sanjeev, Ganesh; Kanjilal, D.; Ojha, Sunil; Dhole, N. A.; Kodam, K. M.; Bhoraskar, V. N.; Dhole, S. D.

    2015-07-01

    Gold (Au)-Polycarbonate (PC) matrix was prepared by gamma radiation assisted diffusion of Au nanoparticles in PC matrix. UV-Visible spectroscopy showed the surface plasmon resonance around 550 nm which corresponds to Au and this peak shift towards lower wavelength i.e. blue shift indicating the decrease in particle size of Au. Rutherford Backscattering (RBS) experiment confirmed the diffusion of Au in PC and depth of diffusion is found to be around 0.85 ?m. X-ray Diffractogram (XRD) results also revealed the diffusion of Au in PC where the peak observed at 2??38.29° which correspond to the FCC structure. Scanning Electron Microscope (SEM) images showed the hexagonal shaped Au nanoparticles and average particle size is found to be around 110 nm. These samples also showed anti-bacterial properties with both gram positive and gram negative bacteria's and revealed the inhibition of the overall growth of the bacteria with gamma dose.

  14. Radiation sickness

    MedlinePLUS

    ... radiation, such as radiation from a nuclear power plant accident Exposure to excessive radiation for medical treatments ... stops ongoing contamination. Vigorously wash the victim with soap and water. Dry the victim and wrap with ...

  15. Radiation therapy

    MedlinePLUS

    Radiation therapy uses high-powered x-rays, particles, or radioactive seeds to kill cancer cells. ... faster than normal cells in the body. Because radiation is most harmful to quickly growing cells, radiation ...

  16. Radiation Therapy

    MedlinePLUS

    Radiation therapy is a cancer treatment. It uses high doses of radiation to kill cancer cells and stop them from ... half of all cancer patients receive it. The radiation may be external, from special machines, or internal, ...

  17. Radiation Therapy

    MedlinePLUS

    ... Your Best Self Smart Snacking Losing Weight Safely Radiation Therapy KidsHealth > Teens > Diseases & Conditions > Cancer & Tumors > Radiation ... how to cope with side effects. What Is Radiation Therapy? Cancer is a disease that causes cells ...

  18. Studies on the accuracy of time-integration methods for the radiation-diffusion equations

    NASA Astrophysics Data System (ADS)

    Ober, Curtis C.; Shadid, John N.

    2004-04-01

    The governing equations for the radiation-diffusion approximation to radiative transport are a system of highly nonlinear, multiple time-scale, partial-differential equations. The numerical solution of these equations for very large-scale simulations is most often carried out using semi-implicit linearization or operator-splitting techniques. These techniques do not fully converge the nonlinearities of the system so as to reduce the cost and complexity of the transient solution at each time step. For a given time-step size, this process exchanges temporal accuracy for computational efficiency. This study considers the temporal-accuracy issue by presenting detailed numerical-convergence studies for problems related to radiation-diffusion simulations. In this context a particular spatial discretization based on a Galerkin finite-element technique is used. The time-integration methods that we consider include: fully implicit, semi-implicit, and operator-splitting techniques. Results are presented for the relative accuracy and the asymptotic order of accuracy of the various methods. The results demonstrate both first-order and second-order asymptotic order of accuracy for the fully implicit, semi-implicit, and the operator-splitting schemes. Additionally a second-order operator-splitting linearized-diffusion method is also presented.

  19. Atmospheric radiation

    SciTech Connect

    Harshvardhan, M.R. )

    1991-01-01

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

  20. Development of Simplified Calculations for a Multipyranometer Array for the Measurement of Direct and Diffuse Solar Radiation 

    E-print Network

    Munger, B. K.; Haberl, J. S.

    2000-01-01

    This paper describes the development of simplified procedures for a multipyranometer array (MPA) for the continuous measurement of direct and diffuse solar radiation. The MPA described in this paper is an improvement over previously published MPA...

  1. A Radiation Chemistry Code Based on the Greens Functions of the Diffusion Equation

    NASA Technical Reports Server (NTRS)

    Plante, Ianik; Wu, Honglu

    2014-01-01

    Ionizing radiation produces several radiolytic species such as.OH, e-aq, and H. when interacting with biological matter. Following their creation, radiolytic species diffuse and chemically react with biological molecules such as DNA. Despite years of research, many questions on the DNA damage by ionizing radiation remains, notably on the indirect effect, i.e. the damage resulting from the reactions of the radiolytic species with DNA. To simulate DNA damage by ionizing radiation, we are developing a step-by-step radiation chemistry code that is based on the Green's functions of the diffusion equation (GFDE), which is able to follow the trajectories of all particles and their reactions with time. In the recent years, simulations based on the GFDE have been used extensively in biochemistry, notably to simulate biochemical networks in time and space and are often used as the "gold standard" to validate diffusion-reaction theories. The exact GFDE for partially diffusion-controlled reactions is difficult to use because of its complex form. Therefore, the radial Green's function, which is much simpler, is often used. Hence, much effort has been devoted to the sampling of the radial Green's functions, for which we have developed a sampling algorithm This algorithm only yields the inter-particle distance vector length after a time step; the sampling of the deviation angle of the inter-particle vector is not taken into consideration. In this work, we show that the radial distribution is predicted by the exact radial Green's function. We also use a technique developed by Clifford et al. to generate the inter-particle vector deviation angles, knowing the inter-particle vector length before and after a time step. The results are compared with those predicted by the exact GFDE and by the analytical angular functions for free diffusion. This first step in the creation of the radiation chemistry code should help the understanding of the contribution of the indirect effect in the formation of DNA damage and double-strand breaks.

  2. Parametric Study of ULF Wave Broadband Spectra and Particle Diffusion in the Radiation Belts

    NASA Astrophysics Data System (ADS)

    Tornquist, M.; Vassiliadis, D.; Koepke, M. E.

    2011-12-01

    We have simulated radial diffusion of mirroring relativistic electrons in the outer radiation caused by a broadband spectrum of waves that cover resonant frequencies of 3-5 mHz (Pc5) with a large marginal. A time-varying phase of each Fourier mode is necessary for generation of diffusive response in particles. Simulation results vary significantly, where in one example for a flat spectrum the diffusion coefficient averaged over 20 simulations is DLL = 3.94±2.72 10-2 h-1. We also investigate diffusion of particles that are not within the resonant frequency band. We show through normalizing the spectral power that the peak electric field amplitude in a spectrum is the dominating factor in the diffusion rate for this case. An inverse power-law, a, with increasing values causes an increase in diffusion rate. Both theory and particle tracing simulations show that the diffusion rate increases exponentially by a factor of 5000 from the flat spectrum (a=0) up to a steep power law of a=1.6 where the rate stagnates. An enhanced transport mechanism is demonstrated by which particles interact with distinct modes coexisting with low amplitude noise background. Resonant particles are transported radially depending on wave amplitudes and frequency adjacency. With coexisting noise some particles can diffusive away from the influential reach of the modes when being close to the outer radial limits, thus additional scattering occurs. By comparing an environment with only noise with another that in addition contains two distinct Chirikov fulfilling modes the standard deviation of radial location of particle population is shown to differ by a maximal factor of 2-6 times depending on the diffusion rate. Finally we simulate particle transport in realistic MHD fields for particular events where ULF activities have been identified. The diffusive behavior is mapped for both original fields and for scenarios where the spectral profiles have been altered to fit ideal specifications as discussed earlier.

  3. Image reconstruction for diffuse optical tomography based on radiative transfer equation.

    PubMed

    Bi, Bo; Han, Bo; Han, Weimin; Tang, Jinping; Li, Li

    2015-01-01

    Diffuse optical tomography is a novel molecular imaging technology for small animal studies. Most known reconstruction methods use the diffusion equation (DA) as forward model, although the validation of DA breaks down in certain situations. In this work, we use the radiative transfer equation as forward model which provides an accurate description of the light propagation within biological media and investigate the potential of sparsity constraints in solving the diffuse optical tomography inverse problem. The feasibility of the sparsity reconstruction approach is evaluated by boundary angular-averaged measurement data and internal angular-averaged measurement data. Simulation results demonstrate that in most of the test cases the reconstructions with sparsity regularization are both qualitatively and quantitatively more reliable than those with standard L? regularization. Results also show the competitive performance of the split Bregman algorithm for the DOT image reconstruction with sparsity regularization compared with other existing L? algorithms. PMID:25648064

  4. Radial diffusion rates of radiation belt electrons as functions of solar wind conditions

    NASA Astrophysics Data System (ADS)

    Huang, Chia-Lin; Spence, Harlan; Hudson, Mary; Elkington, Scot

    We demonstrate new ways to characterize and quantify the effect of ultra-low-frequency (ULF) waves in the inner magnetosphere on radiation belt electron dynamics using a MHD/Particle code. In order to understand the dynamic behavior of radiation belt electrons in ULF wave fields, a global, realistic, self-consistent, and time-dependent magnetospheric model is needed. Therefore, we compare Lyon-Fedder-Mobarry (LFM) code predictions with geosynchronous measurements to assess model performance and to quantify the field fluctuations in the inner magnetosphere. Next, the dynamics of radiation belt electrons are simulated using global magnetic and electric fields from the LFM code, driven by idealized solar wind and IMF data. We follow the trajectories of electrons, starting at different local times and radii for the same first adiabatic invariant, to understand their transport and energization through collective waveparticle interactions. Finally, we quantify the ULF wave effects on radiation belt electrons by calculating the radial diffusion coefficients (DLL ) as functions of solar wind velocity, dynamic pressure variations and IMF Bz.

  5. Quantifying radial diffusion coefficients of radiation belt electrons based on global MHD simulation and spacecraft measurements

    NASA Astrophysics Data System (ADS)

    Tu, Weichao; Elkington, Scot R.; Li, Xinlin; Liu, Wenlong; Bonnell, J.

    2012-10-01

    Radial diffusion is one of the most important acceleration mechanisms for radiation belt electrons, which can be enhanced from drift-resonant interactions with large-scale fluctuations of the magnetosphere's magnetic and electric fields (Pc5 range of ULF waves). In order to physically quantify the radial diffusion coefficient, DLL, we run the global Lyon-Fedder-Mobarry (LFM) MHD simulations to obtain the mode structure and power spectrum of the ULF waves and validate the simulation results with available satellite measurements. The calculated diffusion coefficients, directly from the MHD fields over a Corotating Interaction Region (CIR) storm in March 2008, are generally higher when solar wind dynamic pressure is enhanced or AE index is high. In contrary to the conventional understanding, our results show that inside geosynchronous orbit the total diffusion coefficient from MHD fields is dominated by the contribution from electric field perturbations, rather than the magnetic field perturbations. The calculated diffusion coefficient has a physical dependence on ? (or electron energy) and L, which is missing in the empirical diffusion coefficient, DLLKp as a function of Kp index, and DLLKp are generally greater than our calculated DLL during the storm event. Validation of the MHD ULF waves by spacecraft field data shows that for this event the LFM code reasonably well-reproduces the Bz wave power observed by GOES and THEMIS satellites, while the E? power observed by THEMIS probes are generally underestimated by LFM fields, on average by about a factor of ten.

  6. An experiment to distinguish between diffusive and specular surfaces for thermal radiation in cryogenic gravitational-wave detectors

    NASA Astrophysics Data System (ADS)

    Sakakibara, Yusuke; Kimura, Nobuhiro; Suzuki, Toshikazu; Yamamoto, Kazuhiro; Tokoku, Chihiro; Uchiyama, Takashi; Kuroda, Kazuaki

    2015-07-01

    In cryogenic gravitational-wave detectors, one of the most important issues is the fast cooling of their mirrors and keeping them cool during operation to reduce thermal noise. For this purpose, the correct estimation of thermal-radiation heat transfer through the pipe-shaped radiation shield is vital to reduce the heat load on the mirrors. However, the amount of radiation heat transfer strongly depends on whether the surfaces reflect radiation rays diffusely or specularly. Here, we propose an original experiment to distinguish between diffusive and specular surfaces. This experiment has clearly shown that the examined diamond-like carbon-coated surface is specular. This result emphasizes the importance of suppressing the specular reflection of radiation in the pipe-shaped shield.

  7. Propagation of intense laser radiation through a diffusion flame of burning oil

    NASA Astrophysics Data System (ADS)

    Gvozdev, S. V.; Glova, A. F.; Dubrovskii, V. Yu; Durmanov, S. T.; Krasyukov, A. G.; Lysikov, A. Yu; Smirnov, G. V.; Pleshkov, V. M.

    2015-06-01

    We report the results of measuring the absorption coefficient of radiation from a cw ytterbium fibre single-mode laser with the power up to 1.5 kW by a diffusion flame of oil, burning in the atmosphere air at normal pressure on a free surface. For the constant length (30 mm) and width (30 mm) of the flame and the distance 10 mm between the laser beam axis and the oil surface the dependence of the absorption coefficient, averaged over the flame length, on the mean radiation intensity (varied from 4.5 × 103 to 1.2 × 106 W cm-2) entering the flame is obtained. The qualitative explanation of nonmonotonic behaviour of the absorption coefficient versus the intensity is presented.

  8. An experimental and theoretical study of radiative extinction of diffusion flames

    NASA Technical Reports Server (NTRS)

    Wichman, Indrek S.; Atreya, A.

    1994-01-01

    Our work was primarily theoretical and numerical. We investigated the simplified modeling of heat losses in diffusion flames, then we 'ramped up' the level of complexity in each successive study until the final chapter discussed the general problem of soot/flame interaction. With regard to the specific objective of studying radiative extinction, we conclude that in the steady case a self-extinguishing zero-g flame is unlikely to occur. The soot volume fractions are too small. On the other hand, our work does provide rational means for assessing the mixture of chemical energy release and radiative heat release. It also provides clues for suitable 'tailoring' this balance. Thus heat fluxes to surrounding surfaces can be substantially increased by exploiting and modifying its sooting capability.

  9. Nonlinear variants of the TR/BDF2 method for thermal radiative diffusion

    SciTech Connect

    Edwards, Jarrod D.; Morel, Jim E.; Knoll, Dana A.

    2011-02-20

    We apply the Trapezoidal/BDF2 (TR/BDF2) temporal discretization scheme to nonlinear grey radiative diffusion. This is a scheme that is not well-known within the radiation transport community, but we show that it offers many desirable characteristics relative to other second-order schemes. Several nonlinear variants of the TR/BDF2 scheme are defined and computationally compared with the Crank-Nicholson scheme. It is found for our test problems that the most accurate TR/BDF2 schemes are those that are fully iterated to nonlinear convergence, but the most efficient TR/BDF2 scheme is one based upon a single Newton iteration. It is also shown that neglecting the contributions to the Jacobian matrix from the cross-sections, which is often done due to a lack of smooth interpolations for tabular cross-section data, has a significant impact upon efficiency.

  10. On the origin of the diffuse gamma-ray background radiation

    E-print Network

    Shlomo Dado; Arnon Dar; A De Rujula

    2007-04-08

    We show that inverse Compton scattering of cosmic-microwave-background and starlight photons by cosmic-ray electrons in the interstellar and intergalactic space explains well the spectrum and intensity of the diffuse gamma-ray background radiation (GBR), which was measured by EGRET aboard the Compton Gamma Ray Observatory (CGRO) in directions away from the Galactic disk and centre. The Gamma Ray Large Area Space Telescope (GLAST) will be able to separate the Galactic foreground from the extragalactic gamma-rays, and to provide stringent tests of the theory.

  11. On the origin of the diffuse gamma-ray background radiation

    E-print Network

    Dar, A; De Rújula, Alvaro; Dar, Arnon; Dado, Shlomo

    2007-01-01

    We show that inverse Compton scattering of cosmic-microwave-background and starlight photons by cosmic-ray electrons in the interstellar and intergalactic space explains well the spectrum and intensity of the diffuse gamma-ray background radiation (GBR), which was measured by EGRET aboard the Compton Gamma Ray Observatory (CGRO) in directions away from the Galactic disk and centre. The Gamma Ray Large Area Space Telescope (GLAST) will be able to separate the Galactic foreground from the extragalactic gamma-rays, and to provide stringent tests of the theory.

  12. A Monte Carlo synthetic-acceleration method for solving the thermal radiation diffusion equation

    SciTech Connect

    Evans, Thomas M.; Mosher, Scott W.; Slattery, Stuart R.; Hamilton, Steven P.

    2014-02-01

    We present a novel synthetic-acceleration-based Monte Carlo method for solving the equilibrium thermal radiation diffusion equation in three spatial dimensions. The algorithm performance is compared against traditional solution techniques using a Marshak benchmark problem and a more complex multiple material problem. Our results show that our Monte Carlo method is an effective solver for sparse matrix systems. For solutions converged to the same tolerance, it performs competitively with deterministic methods including preconditioned conjugate gradient and GMRES. We also discuss various aspects of preconditioning the method and its general applicability to broader classes of problems.

  13. Influence of radiation damage on strontium and iodine diffusion in silicon carbide

    NASA Astrophysics Data System (ADS)

    Friedland, E.; van der Berg, N. G.; Malherbe, J. B.; Wendler, E.; Wesch, W.

    2012-06-01

    The transport behaviour of strontium and iodine through single and polycrystalline SiC wafers was investigated using ion beam analysis and electron microscopy. Fluences of 2 × 1016 Sr+ cm-2 and 1 × 1016 I+ cm-2 were implanted at temperatures between 23 °C and 600 °C with an energy of 360 keV, producing an atomic density of approximately 1.5% at the projected ranges of about 120 nm and 90 nm respectively. The broadening of the implantation profiles and its dependence on implantation parameters was determined by isochronal and isothermal annealing studies at temperatures up to 1400 °C. The strong influence of radiation damage on diffusion after room temperature implantations was observed in all cases during the initial annealing stages at 1000 °C. This is a result of the highly disordered crystal lattice, which re-crystallizes at this temperature. In hot implantations this effect is largely reduced but an additional transient diffusion process was observed at 1400 °C for strontium, which is related to defect annealing. Impurity trapping by extended defects is obviously an important effect. Volume diffusion is below our detection limit of 10-21 m2 s-1 for both diffusors. Hence, grain boundary diffusion is responsible for the observed iodine transport in CVD-SiC at 1300 °C, while no significant diffusion of strontium was detected at 1400 °C.

  14. Space Radiation

    NASA Technical Reports Server (NTRS)

    Wu, Honglu

    2006-01-01

    Astronauts receive the highest occupational radiation exposure. Effective protections are needed to ensure the safety of astronauts on long duration space missions. Increased cancer morbidity or mortality risk in astronauts may be caused by occupational radiation exposure. Acute and late radiation damage to the central nervous system (CNS) may lead to changes in motor function and behavior, or neurological disorders. Radiation exposure may result in degenerative tissue diseases (non-cancer or non-CNS) such as cardiac, circulatory, or digestive diseases, as well as cataracts. Acute radiation syndromes may occur due to occupational radiation exposure.

  15. Influence of radiative property models on soot production in laminar coflow ethylene diffusion flames

    NASA Astrophysics Data System (ADS)

    Demarco, Rodrigo; Consalvi, Jean-Louis; Fuentes, Andrés

    2012-06-01

    Two axisymmetric laminar coflow non-smoking and smoking ethylene diffusion flames are studied numerically in order to assess the influence of different radiative property models on the soot formation and oxidation processes. Simulations are carried out by considering the Steady Laminar Flamelet (SLF) concept and a modified two-equation acetylene-based model to describe the soot nucleation, surface growth and oxidation processes. Several radiative property models are considered: the simple Optically Thin Approximation (OTA), the Weighted-Sum of Grey-Gases (WSGG), the Grey-Wide-Band model (GWB), the Statistical Narrow Band Correlated-k model (SNBCK) and the Full Spectrum Correlated-k model (FSCK). Comparisons between calculations carried out with the SNBCK model and experimental data show a reasonable agreement. Model results show that the choice of the radiative property models influence largely the soot prediction, especially in the upper part of the flame where oxidation occurs. Simulations show that the reabsorption of spectral gas and soot is an important feature and thus the commonly used OTA or grey models introduce large discrepancies. The GWB model leads to improved solutions, but it should be avoided if accurate predictions are desired. The FSCK provides equivalent results as compared to the SNBCK model with a substantial gain in CPU time.

  16. Installation of a variable-angle spectrometer system for monitoring diffuse and global solar radiation

    NASA Astrophysics Data System (ADS)

    Ormachea, O.; Abrahamse, A.; Tolavi, N.; Romero, F.; Urquidi, O.; Pearce, J. M.; Andrews, R.

    2013-11-01

    We report on the design and installation of a spectrometer system for monitoring solar radiation in Cochabamba, Bolivia. Both the light intensity and the spectral distribution affect the power produced by a photovoltaic device. Local variations in the solar spectrum (especially compared to the AM1.5 standard) may have important implications for device optimization and energy yield estimation. The spectrometer system, based on an Ocean Optics USB4000 (300-900nm) spectrometer, was designed to increase functionality. Typically systems only record the global horizontal radiation. Our system moves a fiber-optic cable 0-90 degrees and takes measurements in 9 degree increments. Additionally, a shadow band allows measurement of the diffuse component of the radiation at each position. The electronic controls utilize an Arduino UNO microcontroller to synchronizes the movement of two PAP bipolar (stepper) motors with the activation of the spectrometer via an external trigger. The spectrometer was factory calibrated for wavelength and calibrated for absolute irradiance using a Sellarnet SL1-Cal light source. We present preliminary results from data taken March-June, 2013, and comment on implications for PV devices in Cochabamba.

  17. Measurements and Modeling of Soot Formation and Radiation in Microgravity Jet Diffusion Flames. Volume 4

    NASA Technical Reports Server (NTRS)

    Ku, Jerry C.; Tong, Li; Greenberg, Paul S.

    1996-01-01

    This is a computational and experimental study for soot formation and radiative heat transfer in jet diffusion flames under normal gravity (1-g) and microgravity (0-g) conditions. Instantaneous soot volume fraction maps are measured using a full-field imaging absorption technique developed by the authors. A compact, self-contained drop rig is used for microgravity experiments in the 2.2-second drop tower facility at NASA Lewis Research Center. On modeling, we have coupled flame structure and soot formation models with detailed radiation transfer calculations. Favre-averaged boundary layer equations with a k-e-g turbulence model are used to predict the flow field, and a conserved scalar approach with an assumed Beta-pdf are used to predict gaseous species mole fraction. Scalar transport equations are used to describe soot volume fraction and number density distributions, with formation and oxidation terms modeled by one-step rate equations and thermophoretic effects included. An energy equation is included to couple flame structure and radiation analyses through iterations, neglecting turbulence-radiation interactions. The YIX solution for a finite cylindrical enclosure is used for radiative heat transfer calculations. The spectral absorption coefficient for soot aggregates is calculated from the Rayleigh solution using complex refractive index data from a Drude- Lorentz model. The exponential-wide-band model is used to calculate the spectral absorption coefficient for H20 and C02. It is shown that when compared to results from true spectral integration, the Rosseland mean absorption coefficient can provide reasonably accurate predictions for the type of flames studied. The soot formation model proposed by Moss, Syed, and Stewart seems to produce better fits to experimental data and more physically sound than the simpler model by Khan et al. Predicted soot volume fraction and temperature results agree well with published data for a normal gravity co-flow laminar flames and turbulent jet flames. Predicted soot volume fraction results also agree with our data for 1-g and 0-g laminar jet names as well as 1-g turbulent jet flames.

  18. Retrieving direct and diffuse radiation with the use of sky imager pictures

    NASA Astrophysics Data System (ADS)

    Schmidt, Thomas; Kalisch, John; Lorenz, Elke

    2015-04-01

    A machine-learning approach for retrieving direct and diffuse irradiance from pictures taken by a ground-based whole-sky imagery (sky imager) is investigated in the present work. The use of sky imagers for shortest-term local solar irradiance forecasts is a growing field in research and industry. Accurate predictions of surface solar irradiance fluctuations up to 30 minutes ahead are important for a variety of solar energy and power grid applications. Sky imager picture analyses provide very high resolution binary cloud masks, but have limitations in deriving aerosol and cloud optical properties. In a first approach, surface solar irradiance was retrieved from the binary cloud masks with the use of clear sky and overcast irradiance calculations. With this method, forecast performance improvements over persistence could be achieved especially for broken cloud situations. These situations are characterized by inhomogeneous cloud patterns contributing to surface solar irradiance deviating from the clear sky or overcast levels. The accurate estimation of the radiative components will therefore improve the irradiance retrievals. One year of measurements at the University of Oldenburg was used as a robust data basis for this new approach. The data sets consists of direct, diffuse and global horizontal irradiance measured with a sample rate of 1 Hz. In order to account for diurnal and seasonal variations radiation measurements are normalized to the clear-sky conditions. Hemispheric images were taken every 10 s by a sky imager mounted close to the radiometers. The proposed approach uses image features like the average pixel intensity of the whole image and the circumsolar area, analyses of the gray-level co-occurence matrix (GLCM), information of the RGB and HSV color space and the analysed cloud fraction. In order to estimate normalized direct and diffuse radiation, a k-nearest neighbor (k-NN) regression algorithm is applied. The performance of this model is evaluated by cross-validation. Here, the analysis procedure and first results of the performance of this new approach are presented.

  19. Radial diffusion simulations of the 20 September 2007 radiation belt dropout

    NASA Astrophysics Data System (ADS)

    Albert, J.

    2014-08-01

    This is a study of a dropout of radiation belt electrons, associated with an isolated solar wind density pulse on 20 September 2007, as seen by the solid-state telescopes (SST) detectors on THEMIS (Time History of Events and Macroscale Interactions during Substorms). Omnidirectional fluxes were converted to phase space density at constant invariants M = 700 MeV G-1 and K = 0.014 RE G1/2, with the assumption of local pitch angle ? ? 80° and using the T04 magnetic field model. The last closed drift shell, which was calculated throughout the time interval, never came within the simulation outer boundary of L* = 6. It is found, using several different models for diffusion rates, that radial diffusion alone only allows the data-driven, time-dependent boundary values at Lmax = 6 and Lmin = 3.7 to propagate a few tenths of an RE during the simulation; far too slow to account for the dropout observed over the broad range of L* = 4-5.5. Pitch angle diffusion via resonant interactions with several types of waves (chorus, electromagnetic ion cyclotron waves, and plasmaspheric and plume hiss) also seems problematic, for several reasons which are discussed.

  20. Study of a non-diffusing radiochromic gel dosimeter for 3D radiation dose imaging

    NASA Astrophysics Data System (ADS)

    Marsden, Craig Michael

    2000-12-01

    This thesis investigates the potential of a new radiation gel dosimeter, based on nitro-blue tetrazolium (NBTZ) suspended in a gelatin mold. Unlike all Fricke based gel dosimeters this dosimeter does not suffer from diffusive loss of image stability. Images are obtained by an optical tomography method. Nitro blue tetrazolium is a common biological indicator that when irradiated in an aqueous medium undergoes reduction to a highly colored formazan, which has an absorbance maximum at 525nm. Tetrazolium is water soluble while the formazan product is insoluble. The formazan product sticks to the gelatin matrix and the dose image is maintained for three months. Methods to maximize the sensitivity of the system were evaluated. It was found that a chemical detergent, Triton X-100, in combination with sodium formate, increased the dosimeter sensitivity significantly. An initial G-value of formazan production for a dosimeter composed of 1mM NBTZ, gelatin, and water was on the order of 0.2. The addition of Triton and formate produced a G-value in excess of 5.0. The effects of NBTZ, triton, formate, and gel concentration were all investigated. All the gels provided linear dose vs. absorbance plots for doses from 0 to >100 Gy. It was determined that gel concentration had minimal if any effect on sensitivity. Sensitivity increased slightly with increasing NBTZ concentration. Triton and formate individually and together provided moderate to large increases in dosimeter sensitivity. The dosimeter described in this work can provide stable 3D radiation dose images for all modalities of radiation therapy equipment. Methods to increase sensitivity are developed and discussed.

  1. Dynamic implicit 3D adaptive mesh refinement for non-equilibrium radiation diffusion

    NASA Astrophysics Data System (ADS)

    Philip, B.; Wang, Z.; Berrill, M. A.; Birke, M.; Pernice, M.

    2014-04-01

    The time dependent non-equilibrium radiation diffusion equations are important for solving the transport of energy through radiation in optically thick regimes and find applications in several fields including astrophysics and inertial confinement fusion. The associated initial boundary value problems that are encountered often exhibit a wide range of scales in space and time and are extremely challenging to solve. To efficiently and accurately simulate these systems we describe our research on combining techniques that will also find use more broadly for long term time integration of nonlinear multi-physics systems: implicit time integration for efficient long term time integration of stiff multi-physics systems, local control theory based step size control to minimize the required global number of time steps while controlling accuracy, dynamic 3D adaptive mesh refinement (AMR) to minimize memory and computational costs, Jacobian Free Newton-Krylov methods on AMR grids for efficient nonlinear solution, and optimal multilevel preconditioner components that provide level independent solver convergence.

  2. A new, coupled transport-diffusion method for radiative transfer calculations

    SciTech Connect

    Wollaber, A. B.; Warsa, J. S.

    2013-07-01

    We derive and present a new frequency- and angle-integrated low-order system of equations designed to enhance the accuracy of a coupled, high-order (transport) solution of the thermal radiative transfer equations. In particular, our new low-order system is designed to use intensity-weighted opacities and anisotropic diffusion coefficients generated by a solution of the Implicit Monte Carlo (IMC) equations in order to predict the spatial dependence of the material temperature and radiation energies in the ensuing time cycle. The predicted temperature solution can then be exploited to generate appropriately time-centered opacities, specific heats, and Planck emission spectra for the upcoming IMC solution. Additionally, the relatively inexpensive solution of the low-order system can be iteratively solved to recommend an adaptive time step size before the IMC solution is computed. A test implementation has been implemented using existing software available from the Jayenne and Capsaicin projects at Los Alamos National Laboratory. We present initial results from a new driver code that has integrated these stochastic and deterministic software packages. (authors)

  3. Dynamic implicit 3D adaptive mesh refinement for non-equilibrium radiation diffusion

    SciTech Connect

    B. Philip; Z. Wang; M.A. Berrill; M. Birke; M. Pernice

    2014-04-01

    The time dependent non-equilibrium radiation diffusion equations are important for solving the transport of energy through radiation in optically thick regimes and find applications in several fields including astrophysics and inertial confinement fusion. The associated initial boundary value problems that are encountered often exhibit a wide range of scales in space and time and are extremely challenging to solve. To efficiently and accurately simulate these systems we describe our research on combining techniques that will also find use more broadly for long term time integration of nonlinear multi-physics systems: implicit time integration for efficient long term time integration of stiff multi-physics systems, local control theory based step size control to minimize the required global number of time steps while controlling accuracy, dynamic 3D adaptive mesh refinement (AMR) to minimize memory and computational costs, Jacobian Free Newton–Krylov methods on AMR grids for efficient nonlinear solution, and optimal multilevel preconditioner components that provide level independent solver convergence.

  4. Directional Degradation of Spectralon Diffuser Under Ionizing Radiation for Calibration of Space-Based Sensors

    NASA Technical Reports Server (NTRS)

    Georgiev, G. T.; Butler, J. J.; Kowalewski, M. G.; Ding, L.

    2012-01-01

    Assessment of the effect of Vacuum Ultra Violet (VUV) irradiation on the Bidirectional Reflectance Distribution Function (BRDF) of Spectralon is presented in this paper. The sample was a 99% white Spectralon calibration standard irradiated with VUV source positioned at 60o off the irradiation direction for a total of 20 hours. The BRDF before and after VUV irradiation was measured and compared at number of wavelengths in the UV, VIS and IR. Non-isotropic directional degradation of Spectralon diffuser under ionizing radiation was detected at different BRDF measurement geometries primarily at UV spectral range. The 8o directional/hemispherical reflectance of the same sample was also measured and compared from 200nm to 2500nm. Index Terms BRDF, Reflectance, Multiangular, Spectralon, Remote Sensing

  5. On linearization and preconditioning for radiation diffusion coupled to material thermal conduction equations

    SciTech Connect

    Feng, Tao; Graduate School of China Academy Engineering Physics, Beijing 100083 ; An, Hengbin; Yu, Xijun; Li, Qin; Zhang, Rongpei

    2013-03-01

    Jacobian-free Newton–Krylov (JFNK) method is an effective algorithm for solving large scale nonlinear equations. One of the most important advantages of JFNK method is that there is no necessity to form and store the Jacobian matrix of the nonlinear system when JFNK method is employed. However, an approximation of the Jacobian is needed for the purpose of preconditioning. In this paper, JFNK method is employed to solve a class of non-equilibrium radiation diffusion coupled to material thermal conduction equations, and two preconditioners are designed by linearizing the equations in two methods. Numerical results show that the two preconditioning methods can improve the convergence behavior and efficiency of JFNK method.

  6. Implications of polymer electrolyte fuel cell exposure to synchrotron radiation on gas diffusion layer water distribution

    NASA Astrophysics Data System (ADS)

    Eller, Jens; Roth, Jörg; Marone, Federica; Stampanoni, Marco; Wokaun, Alexander; Büchi, Felix N.

    2014-01-01

    Synchrotron radiation (SR) based imaging of polymer electrolyte fuel cells (PEFC), both radiography and tomography, is an attractive tool for the visualization of water in the gas diffusion layer as it provides temporal and spatial resolutions one order of magnitude superior to neutron imaging. Here we report on the degradation of cell performance and changes in GDL water saturation after SR irradiation of about 43% of a cell's active area. Fast X-ray tomographic microscopy (XTM) scans of 11 s duration are used to compare the GDL saturation before and after a 5 min irradiation period of the imaged section. The cell voltage and the water saturation decreased clearly during and after the exposure. Estimates of the current density of the SR exposed and non exposed cell domains underline the effect of irradiation.

  7. Parametric Study of ULF Wave Spectra and Particle Diffusion in the Radiation Belts

    NASA Astrophysics Data System (ADS)

    Tornquist, M.; Vassiliadis, D.; Koepke, M. E.

    2012-12-01

    One of the main mechanisms thought to induce relativistic electron transport and energization in the radiation belt is radial diffusion through interaction with broadband spectra of electromagnetic wave fields. Studies by other research groups have emphasized a correlation between power spectral density and the diffusion coefficient DLL. However the main focus has been on particles interacting resonantly with stationary and ergodic fields where the internal phases are fixed. We propose an analytical function for the diffusion coefficient with an important factor being the introduction of phases that are set to be randomized at fixed time intervals. The calculated diffusion rates are verified through the use of a guiding center test particle code. For a comparison of the results between the analytical function and the test particle code simplified wave fields of m=0 are assigned into azimuthally limited sectors and randomized at fixed intervals. The electrons in the particle tracing code do interact resonantly with the specifically assigned spectra from which resulting diffusion coefficients become higher than for the analytically calculated values of non-resonant interaction. The plotted results suggest that resonant contribution is between 1.5-3.5 times larger than the non-resonant depending on reset rate and harmonic interaction. Should the rate of phase randomization exceed the drift frequency of the electrons the resonant interactions would diminish where only non-resonant diffusion still occurs. Furthermore we show the transition from narrowband to broadband spectra, as well as cases containing both. We will discuss the outcome from varied power law profiles in the spectrum, as well as the difference between using a symmetric and an asymmetric magnetic dipole field. The initial energies and radial placement of the electrons determine their adiabatic invariants which in turn affects the diffusion coefficient. For our setup, where a simplified electrostatic spectrum of m=0 was used, the coefficient was found to be DLL ~ L^7.3 in a symmetric dipole field and DLL ~ L^14.9 in an asymmetric dipole. These values are higher than what have been derived in earlier studies for m>0 and stationary phases.

  8. Hawking radiation

    NASA Astrophysics Data System (ADS)

    Parentani, Renaud; Spindel, Philippe

    2011-12-01

    Hawking radiation is the thermal radiation predicted to be spontaneously emitted by black holes. It arises from the steady conversion of quantum vacuum fluctuations into pairs of particles, one of which escaping at infinity while the other is trapped inside the black hole horizon. It is named after the physicist Stephen Hawking who derived its existence in 1974. This radiation reduces the mass of black holes and is therefore also known as black hole evaporation.

  9. Time-independent hybrid enrichment for finite element solution of transient conduction–radiation in diffusive grey media

    SciTech Connect

    Mohamed, M. Shadi; Seaid, Mohammed; Trevelyan, Jon; Laghrouche, Omar

    2013-10-15

    We investigate the effectiveness of the partition-of-unity finite element method for transient conduction–radiation problems in diffusive grey media. The governing equations consist of a semi-linear transient heat equation for the temperature field and a stationary diffusion approximation to the radiation in grey media. The coupled equations are integrated in time using a semi-implicit method in the finite element framework. We show that for the considered problems, a combination of hyperbolic and exponential enrichment functions based on an approximation of the boundary layer leads to improved accuracy compared to the conventional finite element method. It is illustrated that this approach can be more efficient than using h adaptivity to increase the accuracy of the finite element method near the boundary walls. The performance of the proposed partition-of-unity method is analyzed on several test examples for transient conduction–radiation problems in two space dimensions.

  10. Anti-diffusive-like-behavior in semi-analytic radiative shocks via multigroup Sn transport with constant cross sections

    NASA Astrophysics Data System (ADS)

    Holgado, A. M.; Ferguson, J. M.; McClarren, R. G.

    2015-12-01

    Semi-analytic lab-frame radiative shock solutions have been presented recently, wherein the radiation is modeled with either grey (frequency independent) nonequilibrium-diffusion or grey Sn-transport. As a first step toward incorporating frequency dependence, we retain grey cross-sections such that the frequency dependence of the problem is strictly due to the Planck function. By using multigroup frequency integration the frequency-dependent radiation-transport equation may be solved, and group-dependent radiation temperatures may be defined for each group. Our main result is: When a Zel'dovich temperature spike exists in a radiative shock solution, there exists a transition group gT , such that for all frequency groups below gT the group-dependent radiation temperatures are spatially monotonic, and for all frequency groups above gT the group-dependent radiation temperatures are spatially non-monotonic. We present numerical evidence of our claim and make no claim as to the monotonicity of group gT.

  11. A case study of view-factor rectification procedures for diffuse-gray radiation enclosure computations

    NASA Technical Reports Server (NTRS)

    Taylor, Robert P.; Luck, Rogelio

    1995-01-01

    The view factors which are used in diffuse-gray radiation enclosure calculations are often computed by approximate numerical integrations. These approximately calculated view factors will usually not satisfy the important physical constraints of reciprocity and closure. In this paper several view-factor rectification algorithms are reviewed and a rectification algorithm based on a least-squares numerical filtering scheme is proposed with both weighted and unweighted classes. A Monte-Carlo investigation is undertaken to study the propagation of view-factor and surface-area uncertainties into the heat transfer results of the diffuse-gray enclosure calculations. It is found that the weighted least-squares algorithm is vastly superior to the other rectification schemes for the reduction of the heat-flux sensitivities to view-factor uncertainties. In a sample problem, which has proven to be very sensitive to uncertainties in view factor, the heat transfer calculations with weighted least-squares rectified view factors are very good with an original view-factor matrix computed to only one-digit accuracy. All of the algorithms had roughly equivalent effects on the reduction in sensitivity to area uncertainty in this case study.

  12. Hourly global and diffuse radiation of Lagos, Nigeria-correlation with some atmospheric parameters

    SciTech Connect

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

    1994-03-01

    The influence of four climatic parameters on the hourly diffuse fraction in Lagos, Nigeria, has been studied. Using data for two years, new correlations were established. The standard error of the Liu and Jordan-type equation was reduced by 12.83% when solar elevation, ambient temperature, and relative humidity were used together as predictor variables for the entire data set. Ambient temperature and relative humidity proved to be very important variables for predicting the diffuse fraction of the solar radiation passing through the humid atmosphere of the coastal and tropic city of Lagos. Seasonal analysis carried out with the data showed improvements on the standard errors for the new seasonal correlations. In the case of the dry season, the improvement was 18.37%, whole for the wet season, this was 12.37%. Comparison with existing correlations showed that the performance of the one parameter model (namely K[sub t]), of Orgill and Hollands and Reindl, Beckman, and Duffie were very different from the Liu and Jordan-type model obtained for Lagos.

  13. Controlling diffusion for a self-healing radiation tolerant nanostructured ferritic alloy

    NASA Astrophysics Data System (ADS)

    Miller, M. K.; Parish, C. M.; Bei, H.

    2015-07-01

    Diffusion plays a major role in the stability of microstructures to extreme conditions of high temperature and high doses of irradiation. In nanostructured ferritic alloys, first principle calculations indicate that the binding energy of vacancies is reduced by the presence of oxygen, titanium and yttrium atoms. Therefore, the number of free vacancies available for diffusion can be greatly reduced. The mechanical properties of these alloys, compared to traditional wrought alloys of similar composition and grain structure, is distinctly different, and the ultrafine grained alloy is distinguished by a high number density of Ti-Y-O-enriched nanoclusters and solute clusters, which drives the mechanical response. When a displacement cascade interacts with a nanocluster, the solute atoms are locally dispersed into the matrix by ballistic collisions, but immediately a new nanocluster reforms due to the local supersaturation of solutes and vacancies until the excess vacancies are consumed. The result of these processes is a structural material for advanced energy systems with a microstructure that is self-healing and tolerant to high doses of radiation and high temperatures.

  14. RADIATION BALANCE

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The balance of energy on the earth's surface represents the difference between incoming and outgoing radiation. There are two components in both the incoming and ongoing fractions and are separated by wavelength as shortwave (less than 5 um) and longwave (greater than 5 um). Shortwave radiation or...

  15. Understanding Radiation.

    ERIC Educational Resources Information Center

    Department of Energy, Washington, DC. Nuclear Energy Office.

    Radiation is a natural energy force that has been a part of the environment since the Earth was formed. It takes various forms, none of which can be smelled, tasted, seen, heard, or felt. Nevertheless, scientists know what it is, where it comes from, how to measure and detect it, and how it affects people. Cosmic radiation from outer space and…

  16. Radiation Exposure

    MedlinePLUS

    ... particles. It occurs naturally in sunlight. Man-made radiation is used in X-rays, nuclear weapons, nuclear power plants and cancer treatment. If you are exposed to small amounts of radiation over a long time, it raises your risk ...

  17. Application of a Reynolds stress turbulence model to a supersonic radiating hydrogen-air diffusion flame

    NASA Technical Reports Server (NTRS)

    Chandrasekhar, R.; Tiwari, S. N.

    1993-01-01

    A second-order differential Reynolds Stress turbulence model has been applied to the Favre-averaged Navier-Stokes equations for the study of supersonic flows with finite-rate chemistry and radiation. An assumed Beta Probability Density Function is applied to account for the chemical source terms and the radiative flux terms in the conservation equations. A seven-species, seven-reaction finite rate chemistry mechanism is used to simulate the combustion process. The tangent slab approximation is used in radiative flux formulation. A pseudo-gray gas model is used to represent the absorption-emission characteristics of the participating species. The turbulence/radiation interaction is achieved via a new formulation. The resulting formulation is validated by comparison with experimental data on reacting supersonic axisymmetric jets. Results obtained for specific conditions indicate that the effect of chemical reaction on the turbulence is significant. Also, the radiative heat transfer is enhanced by the turbulence.

  18. Radiation detector

    DOEpatents

    Fultz, B.T.

    1980-12-05

    Apparatus is provided for detecting radiation such as gamma rays and x-rays generated in backscatter Moessbauer effect spectroscopy and x-ray spectrometry, which has a large window for detecting radiation emanating over a wide solid angle from a specimen and which generates substantially the same output pulse height for monoenergetic radiation that passes through any portion of the detection chamber. The apparatus includes a substantially toroidal chamber with conductive walls forming a cathode, and a wire anode extending in a circle within the chamber with the anode lying closer to the inner side of the toroid which has the least diameter than to the outer side. The placement of the anode produces an electric field, in a region close to the anode, which has substantially the same gradient in all directions extending radially from the anode, so that the number of avalanche electrons generated by ionizing radiation is independent of the path of the radiation through the chamber.

  19. Radiation detector

    DOEpatents

    Fultz, Brent T. (Berkeley, CA)

    1983-01-01

    Apparatus is provided for detecting radiation such as gamma rays and X-rays generated in backscatter Mossbauer effect spectroscopy and X-ray spectrometry, which has a large "window" for detecting radiation emanating over a wide solid angle from a specimen and which generates substantially the same output pulse height for monoenergetic radiation that passes through any portion of the detection chamber. The apparatus includes a substantially toroidal chamber with conductive walls forming a cathode, and a wire anode extending in a circle within the chamber with the anode lying closer to the inner side of the toroid which has the least diameter than to the outer side. The placement of the anode produces an electric field, in a region close to the anode, which has substantially the same gradient in all directions extending radially from the anode, so that the number of avalanche electrons generated by ionizing radiation is independent of the path of the radiation through the chamber.

  20. Solar radiation on Mars

    SciTech Connect

    Appelbaum, J.; Flood, D.J.

    1989-08-01

    Detailed information on solar radiation characteristics on Mars are necessary for effective design of future planned solar energy systems operating on the surface of Mars. Presented here is a procedure and solar radiation related data from which the diurnally, hourly and daily variation of the global, direct beam and diffuse insolation on Mars are calculated. The radiation data are based on measured optical depth of the Martian atmosphere derived from images taken of the sun with a special diode on the Viking cameras; and computation based on multiple wavelength and multiple scattering of the solar radiation.

  1. Asymptotic Accuracy of the Equilibrium Diffusion Approximation and Semi-analytic Solutions of Radiating Shocks 

    E-print Network

    Ferguson, Jim Michael

    2014-01-10

    Radiation hydrodynamics (RH) provides a theoretical description for many astrophysical events spanning a wide range of observable phenomena. It is the goal of high-energy-density laboratory astrophysics (HEDLA) to reproduce some of these events...

  2. Fast linear solver for radiative transport equation with multiple right hand sides in diffuse optical tomography

    NASA Astrophysics Data System (ADS)

    Jia, Jingfei; Kim, Hyun K.; Hielscher, Andreas H.

    2015-12-01

    It is well known that radiative transfer equation (RTE) provides more accurate tomographic results than its diffusion approximation (DA). However, RTE-based tomographic reconstruction codes have limited applicability in practice due to their high computational cost. In this article, we propose a new efficient method for solving the RTE forward problem with multiple light sources in an all-at-once manner instead of solving it for each source separately. To this end, we introduce here a novel linear solver called block biconjugate gradient stabilized method (block BiCGStab) that makes full use of the shared information between different right hand sides to accelerate solution convergence. Two parallelized block BiCGStab methods are proposed for additional acceleration under limited threads situation. We evaluate the performance of this algorithm with numerical simulation studies involving the Delta-Eddington approximation to the scattering phase function. The results show that the single threading block RTE solver proposed here reduces computation time by a factor of 1.5-3 as compared to the traditional sequential solution method and the parallel block solver by a factor of 1.5 as compared to the traditional parallel sequential method. This block linear solver is, moreover, independent of discretization schemes and preconditioners used; thus further acceleration and higher accuracy can be expected when combined with other existing discretization schemes or preconditioners.

  3. Radial diffusion in Saturn's radiation belts: a modeling analysis assuming satellite and Ring E absorption

    SciTech Connect

    Hood, L.L.

    1983-02-01

    Phase space density profiles derived by Poineer II and Voyager I investigators for Saturnian radiation-belt protons with zero second adiabatic invariants and first invariants ..mu.. of 600, 1100, 2500, 5000, 10,000, and 20,000 MeV/G have been analyzed for the purpose of inferring the amplitude and L dependence the time-averaged radial diffusion coefficient D(L) in the inner magnetosphere. Three models for solid-body absorption outside of L = 3 were considered. The first included satellite absorption only with satellites represented as simple geometric absorbers in an axially symmetric planetary magnetic field. The remaining two models included additional absorption by Ring E using a representative optical depth profile derived from ground-based telescopic measurements and two possible characteristic latitudinal ring thickness. Minimum Ring E encounter times were estimated by assuming that the mirror latitude appropriate for the sampled protons is less than the maximum magnetic latitude of Rign E. The Ring E encounter times are generally longer than the estimated satellite absorption times for protons of these energies. Additional Ring E loss processes such as charge exchange in a possible associated torus could significantly reduce the effective loss times but are not considered in the present work. A low-order L dependence (D)(L)proportionalL/sup 2/, L/sup 3/, or L/sup 4/) was selected via a minimum-variance criterion for five of the six data profiles studied for either of the three assumed absorption models.

  4. Celestial diffuse gamma radiation above 30 MeV observed by SAS-2

    NASA Technical Reports Server (NTRS)

    Fichtel, C. E.; Kniffen, D. A.; Hartman, R. C.

    1973-01-01

    The Small Astronomy Satellite (SAS)-2, launched on November 15, 1972, carried into orbit a 32-deck magnetic-core digitized spark chamber gamma ray telescope to study celestial gamma radiation in the energy range above 30 MeV. In the study of several regions with b sub 2 15 deg, a finite, diffuse flux of gamma rays with a steep energy spectrum in the energy region from 35 to 200 MeV is observed. Representing the energy spectrum by a power law of the form dJ/dE = AE to - alpha power over this energy range, alpha is found along with the integral flux above 100 MeV. Combining this result with existing low energy gamma ray data yields an energy spectrum which is not a simple power law in energy, as in the X-ray region, but which demonstrates first an increase and then a decrease in slope, consistent within uncertainties with that predicted by cosmological theories, including the continuous production of high energy gamma rays primarily from neutral pi mesons throughout the history of the universe.

  5. Healthful radiation

    SciTech Connect

    Agard, E.T.

    1997-01-01

    This title of this article sounds paradoxical to most people because the general public is not fully aware of the many benefits radiation has brought to people`s healthcare. Radiation has provided the most effective means of noninvasive diagnosis of many diseases, thus reducing the need for exploratory surgery, at significantly reduced risks. Furthermore, radiotherapy has been effective in treating many diseases without surgical removal of the diseased part. The breast is one excellent example of the benefits of radiation in both diagnosis and treatment with preservation. Yet the public still regards radiation as mysterious and dangerous, while trained experts regard it as beneficial with manageable risks. This article suggests ways of presenting this material to the public in a manner that is interesting and informative. 11 refs.

  6. Radiation Therapy

    MedlinePLUS

    ... Radiation (also called x-rays, gamma rays, or photons) either kills tumor cells directly or interferes with ... treatment per day, five days a week, for two to seven weeks. Potiential Side Effects Most people ...

  7. Radiation Transport

    SciTech Connect

    Urbatsch, Todd James

    2015-06-15

    We present an overview of radiation transport, covering terminology, blackbody raditation, opacities, Boltzmann transport theory, approximations to the transport equation. Next we introduce several transport methods. We present a section on Caseology, observing transport boundary layers. We briefly broach topics of software development, including verification and validation, and we close with a section on high energy-density experiments that highlight and support radiation transport.

  8. Diffuse neuroendocrine system: structural and functional effects of radiation injury to amine precursor uptake and decarboxylation (APUD) cells.

    PubMed

    Kvetnoy, I M; Yuzhakov, V V; Molotkov, A O; Bandurko, L N; Brodsky, R A; Yakovleva, N D

    1996-01-01

    The paper presents a review of the results obtained by the authors on the study of external (gamma) and internal (I-131) radiation effects on the functional morphology and linkage of the diffuse neuroendocrine system (DNES) and amine precursor uptake and decarboxylation (APUD) cells of the stomach and duodenum. The investigations performed enabled us to determine that the morphological changes noted in APUD cells had a dose and time dependency. The present study supports the point of view that the radiation initiates serotonin release from APUD cells, which appears to initiate the mechanism of early postirradiation dysfunctions of the gastrointestinal tract and the subsequent adaptive response of DNES. Analysis of our results, together with a review of the literature, indicates that APUD cells actively participate both in pathogenesis of radiation injury and development of organ and tissue radiosensitivity. PMID:9813611

  9. Ab initio molecular dynamics simulation of interstitial diffusion in Ni-Cr alloys and implications for radiation induced segregation

    NASA Astrophysics Data System (ADS)

    Barnard, L.; Morgan, D.

    2014-06-01

    In this study, ab initio molecular dynamics, implemented via density functional theory, is used to simulate self-interstitial diffusion in pure Ni and in the Ni-18 at.% Cr model alloy. Interstitial tracer diffusivities are measured from simulation results for pure Ni and for both Ni and Cr in the Ni-18Cr alloy. An Arrhenius function fit to these tracer diffusivities is then used in a rate theory model for radiation induced segregation, along with the experimentally measured vacancy diffusivities. It is predicted that interstitial diffusion has a tendency to cause Cr enrichment near grain boundaries, partially counterbalancing the tendency for vacancy diffusion to cause Cr depletion. This results in more mild Cr depletion than would result if only the vacancy diffusion were accounted for, in better agreement with experiment. This physical description of RIS in Ni-Cr alloys, which invokes the effects of both vacancy and interstitial diffusion, is distinct from the conventional description which accounts only for the effect of vacancy diffusion.

  10. Radiation injuries/ionizing radiation

    SciTech Connect

    Gooden, D.S.

    1991-01-01

    This book was written to aid trial attorneys involved in radiation litigation. Radiologists and medical physicists will also find it helpful as they prepare for trial, either as a litigant or an expert witness. Two chapters present checklists to guide attorneys for both plaintiffs and defendants. Gooden titles these checklists Elements of Damages and Elements of Proof and leads the reader to conclusions about each of these. One section that will be particularly helpful to attorneys contains sample interrogatories associated with a case of alleged radiation exposure resulting in a late radiation injury. There are interrogatories for the plaintiff to ask the defendant and for the defendant to ask the plaintiff.

  11. Radiation damage of contact structures with diffusion barriers exposed to irradiation with {sup 60}Co{gamma}-ray photons

    SciTech Connect

    Belyaev, A. E.; Boltovets, N. S.; Konakova, R. V. Milenin, V. V.; Sveshnikov, Yu. N.; Sheremet, V. N.

    2010-04-15

    The effect of ionizing radiation of {sup 60}Co {gamma}-ray photons in the dose range 10{sup 4}-2 x 10{sup 9} rad on metal-semiconductor Au-ZrB{sub x}-AlGaN/GaN and Au-TiB{sub x}-Al-Ti-n-GaN contacts and Au-ZrB{sub x}-n-GaN Schottky diodes is examined. The contacts with the TiB{sub x} and ZrB{sub x} diffusion barriers do not degrade under the effect of ionizing radiation if the dose does not exceed 10{sup 8} rad. The Au-ZrB{sub x}-n-GaN Schottky diodes remain stable in the dose range 10{sup 4}-10{sup 6} rad. As the radiation dose is increased to {>=}10{sup 8} rad, the damage to the contact metallization increases and is accompanied by formation of through pores, which is conducive to accumulation of oxygen at the Au-ZrB{sub x}(TiB{sub x}) interfaces and to an increase in mass transport of atoms in contact-forming layers. In this case, irradiation-caused degradation of the Schottky diodes is observed. Possible mechanisms of radiation damage of contact structures with diffusion barriers are analyzed.

  12. Radiation Oncology Treatment Team

    MedlinePLUS

    ... Upper GI What is Radiation Therapy? Find a Radiation Oncologist Last Name: Facility: City: State: Zip Code: ... who specializes in using radiation to treat cancer . Radiation Oncologists Radiation oncologists are the doctors who will ...

  13. Distinction Between Recurrent Glioma and Radiation Injury Using Magnetic Resonance Spectroscopy in Combination With Diffusion-Weighted Imaging

    SciTech Connect

    Zeng, Q.-S. . E-mail: nanwushan@yahoo.com; Li, C.-F.; Liu Hong; Zhen, J.-H.; Feng, D.-C.

    2007-05-01

    Purpose: The aim of this study was to explore the diagnostic effectiveness of magnetic resonance (MR) spectroscopy with diffusion-weighted imaging on the evaluation of the recurrent contrast-enhancing areas at the site of treated gliomas. Methods and Materials: In 55 patients who had new contrast-enhancing lesions in the vicinity of the previously resected and irradiated high-grade gliomas, two-dimensional MR spectroscopy and diffusion-weighted imaging were performed. Spectral data for N-acetylaspartate (NAA), choline (Cho), creatine (Cr), lipid (Lip), and lactate (Lac) were analyzed in conjunction with the apparent diffusion coefficient (ADC) in all patients. Diagnosis of these lesions was assigned by means of follow-up or histopathology. Results: The Cho/NAA and Cho/Cr ratios were significantly higher in recurrent tumor than in regions of radiation injury (p < 0.01). The ADC value and ADC ratios (ADC of contrast-enhancing lesion to matching structure in the contralateral hemisphere) were significantly higher in radiation injury regions than in recurrent tumor (p < 0.01). With MR spectroscopic data, two variables (Cho/NAA and Cho/Cr ratios) were shown to differentiate recurrent glioma from radiation injury, and 85.5% of total subjects were correctly classified into groups. However, with discriminant analysis of MR spectroscopy imaging plus diffusion-weighted imaging, three variables (Cho/NAA, Cho/Cr, and ADC ratio) were identified and 96.4% of total subjects were correctly classified. There was a significant difference between the diagnostic accuracy of the two discriminant analyses (Chi-square = 3.96, p = 0.046). Conclusion: Using discriminant analysis, this study found that MR spectroscopy in combination with ADC ratio, rather than ADC value, can improve the ability to differentiate recurrent glioma and radiation injury.

  14. Precision structural diagnostics of layered superconductor/ferromagnet nanosystems V/Fe by reflectometry and diffuse scattering of synchrotron radiation

    SciTech Connect

    Nikitin, A. M.; Borisov, M. M.; Mukhamedzhanov, E. Kh.; Kovalchuk, M. V.; Sajti, S.; Tancziko, F.; Deak, L.; Bottyan, L.; Khaydukov, Yu. N.; Aksenov, V. L.

    2011-09-15

    Layered superconducting ferromagnetic nanosystems Cu(32 nm)/V(40-80 nm)/Fe(0.5-4 nm)/MgO(001) have been investigated by reflectometry and the diffuse scattering of synchrotron radiation. The data obtained make it possible to determine the important characteristics of samples such as the layer thickness and the rms heights and lateral correlation lengths of roughness at the interfaces.

  15. Diffusion-weighted and PET/MR Imaging after Radiation Therapy for Malignant Head and Neck Tumors.

    PubMed

    Varoquaux, Arthur; Rager, Olivier; Dulguerov, Pavel; Burkhardt, Karim; Ailianou, Angeliki; Becker, Minerva

    2015-01-01

    Interpreting imaging studies of the irradiated neck constitutes a challenge because of radiation therapy-induced tissue alterations, the variable appearances of recurrent tumors, and functional and metabolic phenomena that mimic disease. Therefore, morphologic magnetic resonance (MR) imaging, diffusion-weighted (DW) imaging, positron emission tomography with computed tomography (PET/CT), and software fusion of PET and MR imaging data sets are increasingly used to facilitate diagnosis in clinical practice. Because MR imaging and PET often yield complementary information, PET/MR imaging holds promise to facilitate differentiation of tumor recurrence from radiation therapy-induced changes and complications. This review focuses on clinical applications of DW and PET/MR imaging in the irradiated neck and discusses the added value of multiparametric imaging to solve diagnostic dilemmas. Radiologists should understand key features of radiation therapy-induced tissue alterations and potential complications seen at DW and PET/MR imaging, including edema, fibrosis, scar tissue, soft-tissue necrosis, bone and cartilage necrosis, cranial nerve palsy, and radiation therapy-induced arteriosclerosis, brain necrosis, and thyroid disorders. DW and PET/MR imaging also play a complementary role in detection of residual and recurrent disease. Interpretation pitfalls due to technical, functional, and metabolic phenomena should be recognized and avoided. Familiarity with DW and PET/MR imaging features of expected findings, potential complications, and treatment failure after radiation therapy increases diagnostic confidence when interpreting images of the irradiated neck. Online supplemental material is available for this article. PMID:26252192

  16. Repetitively pulsed UV radiation source based on a run-away electron preionised diffuse discharge in nitrogen

    NASA Astrophysics Data System (ADS)

    Baksht, E. Kh; Burachenko, A. G.; Lomaev, M. I.; Panchenko, A. N.; Tarasenko, V. F.

    2015-04-01

    An extended repetitively pulsed source of spontaneous UV radiation is fabricated, which may also be used for producing laser radiation. Voltage pulses with an incident wave amplitude of up to 30 kV, a half-amplitude duration of ~4 ns and a rise time of ~2.5 ns are applied to a gap with a nonuniform electric field. For an excitation region length of 35 cm and a nitrogen pressure of 30 - 760 Torr, a diffusive discharge up to a pulse repetition rate of 2 kHz is produced without using an additional system for gap preionisation. An investigation is made of the plasma of the run-away electron preionised diffuse discharge. Using a CCD camera it is found that the dense diffused plasma fills the gap in a time shorter than 1 ns. X-ray radiation is recorded from behind the foil anode throughout the pressure range under study; a supershort avalanche electron beam is recorded by the collector electrode at pressures below 100 Torr.

  17. Effects of Cyclotron-Drift and Bounce-Drift Cross Diffusion on Evolution of Radiation Belt Phase-Space Densites

    NASA Astrophysics Data System (ADS)

    Chan, A. A.; Zheng, L.; O'Brien, T. P., III; Elkington, S. R.; Albert, J.

    2014-12-01

    Pitch-angle scattering coupled with drift-shell splitting in an asymmetric magnetic field can give cyclotron-drift and bounce-drift cross diffusion terms in the radiation belt Fokker-Planck equation. More specifically, cyclotron-resonant pitch-angle scattering coupled with pitch-angle dependent second and third adiabatic invariants gives rise to non-zero DML and DKL cross diffusion coefficients (where M is the first invariant, K is the usual geometric bounce invariant, and L is the Roederer L-shell), plus an additional "anomalous" contribution to the radial diffusion coefficient, DALL [O'Brien, GRL, 2014]. In this paper we describe calculations of these additional terms and we present solutions of the corresponding radiation belt Fokker-Planck equation. The DML, DKL, and DALL diffusion coefficients are calculated assuming a Tsyganenko 1989 magnetic field model and a chorus wave model from Shprits et al. [JGR, 2011] that includes dayside and nightside chorus waves. Solutions to the corresponding Fokker-Planck diffusion equation are obtained using the REM diffusion code, which uses stochastic differential equation (SDE) methods to solve the fully 3-D diffusion equation in adiabatic invariant coordinates. One of the advantages of the SDE methods is that off-diagonal diffusion tensor terms are easily incorporated and the resulting phase-space densities are always non-negative. Initial results show that the new drift-shell splitting contributions are stronger for electrons of a few hundred keV near geosynchronous orbit, with associated changes in MeV electron phase-space densities over a range of L-values and at later times.

  18. Radiation receiver

    DOEpatents

    Hunt, A.J.

    1983-09-13

    The apparatus for collecting radiant energy and converting same to alternate energy form includes a housing having an interior space and a radiation transparent window allowing, for example, solar radiation to be received in the interior space of the housing. Means are provided for passing a stream of fluid past said window and for injecting radiation absorbent particles in said fluid stream. The particles absorb the radiation and because of their very large surface area, quickly release the heat to the surrounding fluid stream. The fluid stream particle mixture is heated until the particles vaporize. The fluid stream is then allowed to expand in, for example, a gas turbine to produce mechanical energy. In an aspect of the present invention properly sized particles need not be vaporized prior to the entrance of the fluid stream into the turbine, as the particles will not damage the turbine blades. In yet another aspect of the invention, conventional fuel injectors are provided to inject fuel into the fluid stream to maintain the proper temperature and pressure of the fluid stream should the source of radiant energy be interrupted. In yet another aspect of the invention, an apparatus is provided which includes means for providing a hot fluid stream having hot particles disbursed therein which can radiate energy, means for providing a cooler fluid stream having cooler particles disbursed therein, which particles can absorb radiant energy and means for passing the hot fluid stream adjacent the cooler fluid stream to warm the cooler fluid and cooler particles by the radiation from the hot fluid and hot particles. 5 figs.

  19. Radiation receiver

    DOEpatents

    Hunt, Arlon J. (Oakland, CA)

    1983-01-01

    The apparatus for collecting radiant energy and converting same to alternate energy form includes a housing having an interior space and a radiation transparent window allowing, for example, solar radiation to be received in the interior space of the housing. Means are provided for passing a stream of fluid past said window and for injecting radiation absorbent particles in said fluid stream. The particles absorb the radiation and because of their very large surface area, quickly release the heat to the surrounding fluid stream. The fluid stream particle mixture is heated until the particles vaporize. The fluid stream is then allowed to expand in, for example, a gas turbine to produce mechanical energy. In an aspect of the present invention properly sized particles need not be vaporized prior to the entrance of the fluid stream into the turbine, as the particles will not damage the turbine blades. In yet another aspect of the invention, conventional fuel injectors are provided to inject fuel into the fluid stream to maintain the proper temperature and pressure of the fluid stream should the source of radiant energy be interrupted. In yet another aspect of the invention, an apparatus is provided which includes means for providing a hot fluid stream having hot particles disbursed therein which can radiate energy, means for providing a cooler fluid stream having cooler particles disbursed therein, which particles can absorb radiant energy and means for passing the hot fluid stream adjacent the cooler fluid stream to warm the cooler fluid and cooler particles by the radiation from the hot fluid and hot particles.

  20. Radiation dermatitis

    SciTech Connect

    Shack, R.B.; Lynch, J.B.

    1987-04-01

    Even in this era of modern radiotherapy, injuries associated with the medical and industrial use of radiation devices will continue to pose a difficult problem for the reconstructive surgeon. It must be borne in mind that the single most serious hazard to surgery in irradiated tissue is the lodgement of bacteria in tissue rendered avascular by the radiation and the secondary necrosis from the infection itself. The basic principles of wound management must be augmented by thorough knowledge of the use of well-vascularized muscle and musculocutaneous flap to provide adequate, blood-rich, soft-tissue coverage.

  1. Problems in astrophysical radiation hydrodynamics

    SciTech Connect

    Castor, J.I.

    1983-09-14

    The basic equations of radiation hydrodynamics are discussed in the regime that the radiation is dynamically as well as thermally important. Particular attention is paid to the question of what constitutes an acceptable approximate non-relativistic system of dynamical equations for matter and radiation in this regime. Further discussion is devoted to two classes of application of these ideas. The first class consists of problems dominated by line radiation, which is sensitive to the velocity field through the Doppler effect. The second class is of problems in which the advection of radiation by moving matter dominates radiation diffusion.

  2. Radiation-enhanced thermal diffusion of transition metal and rare earth ions into II-VI semiconductors

    NASA Astrophysics Data System (ADS)

    Martinez, Alán.; Williams, Lamario; Gafarov, Ozarfar; Martyshkin, Dmitry; Fedorov, Vladimir; Mirov, Sergey

    2015-02-01

    We report on study of gamma radiation-enhanced thermal diffusion of Transition Metal and Rare Earth ions into IIVI semiconductor crystals. ZnSe and ZnS samples with of iron thin film deposited on one facet were sealed in evacuated quartz ampoules at 10-3 Torr. The crystals were annealed for 14 days at 950°C under ?-irradiation from 60Co source. The irradiation dose rates of 43.99 R/s, 1.81 R/s were varied by distance between 60Co source and furnaces. For comparison, the samples were also annealed without irradiation at the same temperature. The spatial distributions of transition metal were measured by absorption of focused laser radiation at 5T2-5E mid-IR transitions of iron ions. In addition, samples of ZnSe were similarly sealed in evacuated quartz ampoules in the presence of Praseodymium metal and annealed at 950°C under 43.99 R/s and 0 R/s and the diffusion lengths and Pr concentrations were compared. The ?-irradiation results in better intrusion of the iron ions from the metal film and increase of the diffusion length at ~25%, while Praseodymium diffusion is dramatically enhanced by ?-irradiation during the annealing process.

  3. Diffusive radiation in one-dimensional Langmuir turbulence G. D. Fleishman1

    E-print Network

    , in the shock front or at the shock-shock interactions. The shape of the radiation spectra is shown to depend 15­20 . However, the de- tailed treatment of the DRL spectral shape in various regimes is currently the perturbation theory and determines the region of applicabil- ity of the perturbative treatment. Electromagnetic

  4. Radiation accidents.

    PubMed

    Saenger, E L

    1986-09-01

    It is essential that emergency physicians understand ways to manage patients contaminated by radioactive materials and/or exposed to external radiation sources. Contamination accidents require careful surveys to identify the metabolic pathway of the radionuclides to guide prognosis and treatment. The level of treatment required will depend on careful surveys and meticulous decontamination. There is no specific therapy for the acute radiation syndrome. Prophylactic antibodies are desirable. For severely exposed patients treatment is similar to the supportive care given to patients undergoing organ transplantation. For high-dose extremity injury, no methods have been developed to reverse the fibrosing endarteritis that eventually leads to tissue death so frequently found with this type of injury. Although the Three Mile Island episode of March 1979 created tremendous public concern, there were no radiation injuries. The contamination outside the reactor building and the release of radioiodine were negligible. The accidental fuel element meltdown at Chernobyl, USSR, resulted in many cases of acute radiation syndrome. More than 100,000 people were exposed to high levels of radioactive fallout. The general principles outlined here are applicable to accidents of that degree of severity. PMID:3526994

  5. Ionizing radiation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This chapter gives a comprehensive review on ionizing irradiation of fresh fruits and vegetables. Topics include principles of ionizing radiation, its effects on pathogenic and spoilage microorganisms, shelf-life, sensory quality, nutritional and phytochemical composition, as well as physiologic and...

  6. Radiation Models

    ERIC Educational Resources Information Center

    James, W. G. G.

    1970-01-01

    Discusses the historical development of both the wave and the corpuscular photon model of light. Suggests that students should be informed that the two models are complementary and that each model successfully describes a wide range of radiation phenomena. Cites 19 references which might be of interest to physics teachers and students. (LC)

  7. Circumsolar radiation

    SciTech Connect

    Watt, A.D.

    1980-04-01

    A quantitative knowledge of circumsolar radiation is important in the design of focusing type solar collectors, and is also of interest to those calculating the performance of all types of collectors. The primary objective of this study is the development of a model which will permit estimation of circumsolar radiation based on solar and meteorological input data. The results of observations are presented including radiance characteristics and time variations of the circumsolar component at a number of locations. The characteristics of the atmosphere are presented with primary emphasis on large particles. Physical models of circumsolar radiation are developed. The results of observed clear day only and all day average monthly values at Albuquerque, NM are shown. Also shown are calculated values for both clear and average days based on the physical model. The model results are based on: long term average turbidity values, derived average pollen loadings, and actual monthly average sky cover values for the years shown. Regression analysis is employed to determine the circumsolar values based on observed solar radiation and atmospheric parameters. The regression derived models show that fairly good agreement can be obtained between observed and calculated monthly average circumsolar ratios by simple expressions employing only the active cavity radiometer values. (WHK)

  8. Discontinuous finite element solution of the radiation diffusion equation on arbitrary polygonal meshes and locally adapted quadrilateral grids

    SciTech Connect

    Ragusa, Jean C.

    2015-01-01

    In this paper, we propose a piece-wise linear discontinuous (PWLD) finite element discretization of the diffusion equation for arbitrary polygonal meshes. It is based on the standard diffusion form and uses the symmetric interior penalty technique, which yields a symmetric positive definite linear system matrix. A preconditioned conjugate gradient algorithm is employed to solve the linear system. Piece-wise linear approximations also allow a straightforward implementation of local mesh adaptation by allowing unrefined cells to be interpreted as polygons with an increased number of vertices. Several test cases, taken from the literature on the discretization of the radiation diffusion equation, are presented: random, sinusoidal, Shestakov, and Z meshes are used. The last numerical example demonstrates the application of the PWLD discretization to adaptive mesh refinement.

  9. The Survey for Ionization in Neutral-Gas Galaxies: III. Diffuse, Warm Ionized Medium and Escape of Ionizing Radiation

    E-print Network

    M. S. Oey; G. R. Meurer; S. Yelda; E. J. Furst; S. M. Caballero-Nieves; D. J. Hanish; E. M. Levesque; D. A. Thilker; G. L. Walth; the SINGG Team

    2007-03-01

    We use the first data release from the SINGG H-alpha survey of HI-selected galaxies to study the quantitative behavior of the diffuse, warm ionized medium (WIM) across the range of properties represented by these 109 galaxies. The mean fraction f_WIM of diffuse ionized gas in this sample is 0.59+/- 0.19, slightly higher than found in previous samples. Since lower surface-brightness galaxies tend to have higher f_WIM, we believe that most of this difference is due to selection effects favoring large, optically-bright, nearby galaxies with high star-formation rates. As found in previous studies, there is no appreciable correlation with Hubble type or total star-formation rate. However, we find that starburst galaxies, defined here by an H-alpha surface brightness > 2.5x 10^39 erg s^-1 kpc^-2 within the H-alpha half-light radius, do show much lower fractions of diffuse H-alpha emission. The cause apparently is not dominated by a lower fraction of field OB stars. However, it is qualitatively consistent with an expected escape of ionizing radiation above a threshold star-formation rate, predicted from our model in which the ISM is shredded by pressure-driven supernova feedback. The HI gas fractions in the starburst galaxies are also lower, suggesting that the starbursts are consuming and ionizing all the gas, and thus promoting regions of density-bounded ionization. If true, these effects imply that some amount of Lyman continuum radiation is escaping from most starburst galaxies, and that WIM properties and outflows from mechanical feedback are likely to be pressure-driven. However, in view of previous studies showing that the escape fraction of ionizing radiation is generally low, it is likely that other factors also drive the low fractions of diffuse ionized gas in starbursts.

  10. A multigroup diffusion solver using pseudo transient continuation for a radiation-hydrodynamic code with patch-based AMR

    NASA Astrophysics Data System (ADS)

    Shestakov, Aleksei I.; Offner, Stella S. R.

    2008-01-01

    We present a scheme to solve the nonlinear multigroup radiation diffusion (MGD) equations. The method is incorporated into a massively parallel, multidimensional, Eulerian radiation-hydrodynamic code with Adaptive Mesh Refinement (AMR). The patch-based AMR algorithm refines in both space and time creating a hierarchy of levels, coarsest to finest. The physics modules are time-advanced using operator splitting. On each level, separate "level-solve" packages advance the modules. Our multigroup level-solve adapts an implicit procedure which leads to a two-step iterative scheme that alternates between elliptic solves for each group with intra-cell group coupling. For robustness, we introduce pseudo transient continuation (?tc). We analyze the magnitude of the ?tc parameter to ensure positivity of the resulting linear system, diagonal dominance and convergence of the two-step scheme. For AMR, a level defines a subdomain for refinement. For diffusive processes such as MGD, the refined level uses Dirichlet boundary data at the coarse-fine interface and the data is derived from the coarse level solution. After advancing on the fine level, an additional procedure, the sync-solve (SS), is required in order to enforce conservation. The MGD SS reduces to an elliptic solve on a combined grid for a system of G equations, where G is the number of groups. We adapt the "partial temperature" scheme for the SS; hence, we reuse the infrastructure developed for scalar equations. Results are presented. We consider a multigroup test problem with a known analytic solution. We demonstrate utility of ?tc by running with increasingly larger timesteps. Lastly, we simulate the sudden release of energy Y inside an Al sphere (r = 15 cm) suspended in air at STP. For Y = 11 kT, we find that gray radiation diffusion and MGD produce similar results. However, if Y = 1 MT, the two packages yield different results. Our large Y simulation contradicts a long-standing theory and demonstrates the inadequacy of gray diffusion.

  11. Calculate Your Radiation Dose

    MedlinePLUS

    EPA United States Environmental Protection Agency Search Search Radiation Protection Share Facebook Twitter Google+ Pinterest Contact Us Radiation Protection Document Library View and download EPA radiation ...

  12. Quantifying equation-of-state and opacity errors using integrated supersonic diffusive radiation flow experiments on the National Ignition Facility

    NASA Astrophysics Data System (ADS)

    Guymer, T. M.; Moore, A. S.; Morton, J.; Kline, J. L.; Allan, S.; Bazin, N.; Benstead, J.; Bentley, C.; Comley, A. J.; Cowan, J.; Flippo, K.; Garbett, W.; Hamilton, C.; Lanier, N. E.; Mussack, K.; Obrey, K.; Reed, L.; Schmidt, D. W.; Stevenson, R. M.; Taccetti, J. M.; Workman, J.

    2015-04-01

    A well diagnosed campaign of supersonic, diffusive radiation flow experiments has been fielded on the National Ignition Facility. These experiments have used the accurate measurements of delivered laser energy and foam density to enable an investigation into SESAME's tabulated equation-of-state values and CASSANDRA's predicted opacity values for the low-density C8H7Cl foam used throughout the campaign. We report that the results from initial simulations under-predicted the arrival time of the radiation wave through the foam by ?22%. A simulation study was conducted that artificially scaled the equation-of-state and opacity with the intended aim of quantifying the systematic offsets in both CASSANDRA and SESAME. Two separate hypotheses which describe these errors have been tested using the entire ensemble of data, with one being supported by these data.

  13. Quantifying equation-of-state and opacity errors using integrated supersonic diffusive radiation flow experiments on the National Ignition Facility

    SciTech Connect

    Guymer, T. M. Moore, A. S.; Morton, J.; Allan, S.; Bazin, N.; Benstead, J.; Bentley, C.; Comley, A. J.; Garbett, W.; Reed, L.; Stevenson, R. M.; Kline, J. L.; Cowan, J.; Flippo, K.; Hamilton, C.; Lanier, N. E.; Mussack, K.; Obrey, K.; Schmidt, D. W.; Taccetti, J. M.; and others

    2015-04-15

    A well diagnosed campaign of supersonic, diffusive radiation flow experiments has been fielded on the National Ignition Facility. These experiments have used the accurate measurements of delivered laser energy and foam density to enable an investigation into SESAME's tabulated equation-of-state values and CASSANDRA's predicted opacity values for the low-density C{sub 8}H{sub 7}Cl foam used throughout the campaign. We report that the results from initial simulations under-predicted the arrival time of the radiation wave through the foam by ?22%. A simulation study was conducted that artificially scaled the equation-of-state and opacity with the intended aim of quantifying the systematic offsets in both CASSANDRA and SESAME. Two separate hypotheses which describe these errors have been tested using the entire ensemble of data, with one being supported by these data.

  14. A Criterion for Photoionization of Pregalactic Clouds Exposed to Diffuse Ultraviolet Background Radiation

    E-print Network

    Yukiko Tajiri; Masayuki Umemura

    1998-06-03

    To elucidate the permeation of cosmic ultraviolet (UV) background radiation into a pregalactic cloud and subsequent ionization, the frequency-dependent radiative transfer equation is solved, coupled with the ionization process. A spherical top-hat cloud which is composed of pure hydrogen is assumed. As a result, it is shown that the self-shielding, although it is often disregarded in cosmological hydrodynamic simulations, could start to emerge shortly after the maximum expansion stages of density fluctuations. The present analysis reveals that the Stro"mgren approximation leads to overestimation of the photoionization effects. Also, the self-shielded neutral core is no longer sharply separated from surrounding ionized regions; a low but noticeable degree of ionization is caused by high energy photons even in the self-shielded core. The present results may be substantial on considering the biasing by photoionization against low-mass galaxy formation.

  15. Hypofractionation vs Conventional Radiation Therapy for Newly Diagnosed Diffuse Intrinsic Pontine Glioma: A Matched-Cohort Analysis

    SciTech Connect

    Janssens, Geert O.; Jansen, Marc H.; Nowak, Peter J.; Oldenburger, Foppe R.; Bouffet, Eric; Kamphuis-van Ulzen, Karin; Lindert, Erik J. van; Schieving, Jolanda H.; Boterberg, Tom; Kaspers, Gertjan J.; Gidding, Corrie E.; Hargrave, Darren

    2013-02-01

    Purpose: Despite conventional radiation therapy, 54 Gy in single doses of 1.8 Gy (54/1.8 Gy) over 6 weeks, most children with diffuse intrinsic pontine glioma (DIPG) will die within 1 year after diagnosis. To reduce patient burden, we investigated the role of hypofractionation radiation therapy given over 3 to 4 weeks. A 1:1 matched-cohort analysis with conventional radiation therapy was performed to assess response and survival. Methods and Materials: Twenty-seven children, aged 3 to 14, were treated according to 1 of 2 hypofractionation regimens over 3 to 4 weeks (39/3 Gy, n=16 or 44.8/2.8 Gy, n=11). All patients had symptoms for {<=}3 months, {>=}2 signs of the neurologic triad (cranial nerve deficit, ataxia, long tract signs), and characteristic features of DIPG on magnetic resonance imaging. Twenty-seven patients fulfilling the same diagnostic criteria and receiving at least 50/1.8 to 2.0 Gy were eligible for the matched-cohort analysis. Results: With hypofractionation radiation therapy, the overall survival at 6, 9, and 12 months was 74%, 44%, and 22%, respectively. Progression-free survival at 3, 6, and 9 months was 77%, 43%, and 12%, respectively. Temporary discontinuation of steroids was observed in 21 of 27 (78%) patients. No significant difference in median overall survival (9.0 vs 9.4 months; P=.84) and time to progression (5.0 vs 7.6 months; P=.24) was observed between hypofractionation vs conventional radiation therapy, respectively. Conclusions: For patients with newly diagnosed DIPG, a hypofractionation regimen, given over 3 to 4 weeks, offers equal overall survival with less treatment burden compared with a conventional regimen of 6 weeks.

  16. Noninvasive diffuse optical measurement of blood flow and blood oxygenation for monitoring radiation

    E-print Network

    Yodh, Arjun G.

    THC re- sponses to chemo-radiation therapy in patients with head and neck tumors. rBF, StO2, and THC period. The weekly rBF, StO2, and THC kinetics exhibit different patterns for different individuals from 62.9±3.4 % base- line value to 70.4±3.2 % at the end of the second week, and aver- aged THC

  17. Acute Radiation Syndrome

    MedlinePLUS

    ... Planning Information on Specific Types of Emergencies Acute Radiation Syndrome (ARS): A Fact Sheet for the Public ... is called the radiation dose. People exposed to radiation will get ARS only if: The radiation dose ...

  18. Radiation Therapy (For Parents)

    MedlinePLUS

    ... Kids Deal With Bullies Pregnant? What to Expect Radiation Therapy KidsHealth > Parents > Doctors & Hospitals > Doctor & Hospital Visits > ... have many questions and concerns about it. About Radiation Therapy In radiation therapy, high-energy radiation from ...

  19. First Order Chemical Reaction Effects on Exponentially Accelerated Vertical Plate with Variable Mass Diffusion in the Presence of Thermal Radiation

    NASA Astrophysics Data System (ADS)

    Muthucumaraswamy, R.; Lakshmi, C. S.

    2015-05-01

    Effects of transfer of mass and free convection on the flow field of an incompressible viscous fluid past an exponentially accelerated vertical plate with variable surface temperature and mass diffusion are studied. Results for velocity, concentration, temperature are obtained by solving governing equations using the Laplace transform technique. It is observed that the velocity increases with decreasing values of the chemical reaction parameter or radiation parameter. But the trend is just reversed with respect to the time parameter. The skin friction is also studied.

  20. Change in Diffusing Capacity After Radiation as an Objective Measure for Grading Radiation Pneumonitis in Patients Treated for Non-Small-Cell Lung Cancer

    SciTech Connect

    Lopez Guerra, Jose Luis; Department of Radiation Oncology, Hospitales Universitarios Virgen del Rocio, Seville ; Gomez, Daniel; Zhuang Yan; Levy, Lawrence B.; Eapen, George; Liu Hongmei; Mohan, Radhe; Komaki, Ritsuko; Cox, James D.; Liao Zhongxing

    2012-08-01

    Purpose: Scoring of radiation pneumonitis (RP), a dose-limiting toxicity after thoracic radiochemotherapy, is subjective and thus inconsistent among studies. Here we investigated whether the extent of change in diffusing capacity of the lung for carbon monoxide (DLCO) after radiation therapy (RT) for non-small-cell lung cancer (NSCLC) could be used as an objective means of quantifying RP. Patients and Methods: We analyzed potential correlations between DLCO and RP in 140 patients who received definitive RT ({>=}60 Gy) with or without chemotherapy for primary NSCLC. All underwent DLCO analysis before and after RT. Post-RT DLCO values within 1 week of the RP diagnosis (Grade 0, 1, 2, or 3) were selected and compared with that individual's preradiation values. Percent reductions in DLCO and RP grade were compared by point biserial correlation in the entire patient group and in subgroups stratified according to various clinical factors. Results: Patients experiencing Grade 0, 1, 2, or 3 RP had median percentage changes in DLCO after RT of 10.7%, 13%, 22.1%, or 35.2%. Percent reduction in DLCO correlated with RP Grade {<=}1 vs. {>=}2 (p = 0.0004). This association held for the following subgroups: age {>=}65 years, advanced stage, smokers, use of chemotherapy, volume of normal lung receiving at least 20 Gy {>=}30%, and baseline DLCO or forced expiratory volume in 1 second {>=}60%. Conclusions: By correlating percent change in DLCO from pretreatment values at the time of diagnosis of RP with RP grade, we were able to identify categories of RP based on the change in DLCO. These criteria provide a basis for an objective scoring system for RP based on change in DLCO.

  1. Fundamental Radiation Concepts

    E-print Network

    Slatton, Clint

    Fundamental Radiation Concepts Alyson Cieply University of Florida Environmental Health and Safety Radiation Control #12;What is radiation? Radiation is energy that travels through space or matter in the form of a particle or wave The effect radiation has on matter depends on the type of radiation and how

  2. A Monte Carlo Synthetic-Acceleration Method for Solving the Thermal Radiation Diffusion Equation

    SciTech Connect

    Evans, Thomas M; Mosher, Scott W; Slattery, Stuart

    2014-01-01

    We present a novel synthetic-acceleration based Monte Carlo method for solving the equilibrium thermal radiation diusion equation in three dimensions. The algorithm performance is compared against traditional solution techniques using a Marshak benchmark problem and a more complex multiple material problem. Our results show that not only can our Monte Carlo method be an eective solver for sparse matrix systems, but also that it performs competitively with deterministic methods including preconditioned Conjugate Gradient while producing numerically identical results. We also discuss various aspects of preconditioning the method and its general applicability to broader classes of problems.

  3. Shortwave Radiation

    NASA Technical Reports Server (NTRS)

    Klassen, Steve; Bugbee, Bruce

    2005-01-01

    Accurate shortwave radiation data is critical to evapotranspiration (ET) models used for developing irrigation schedules to optimize crop production while saving water, minimizing fertilizer, herbicide, and pesticide applications, reducing soil erosion, and protecting surface and ground water quality. Low cost silicon cell pyranometers have proven to be sufficiently accurate and robust for widespread use in agricultural applications under unobstructed daylight conditions. More expensive thermopile pyranometers are required for use as calibration standards and measurements under light with unique spectral properties (electric lights, under vegetation, in greenhouses and growth chambers). Routine cleaning, leveling, and annual calibration checks will help to ensure the integrity of long-term data.

  4. Radiation protection in space.

    PubMed

    Reitz, G; Facius, R; Sandler, H

    1995-01-01

    Radiation environment, basic concepts of radiation protection, and specific aspects of the space radiation field are reviewed. The discussion of physico-chemical and subcellular radiation effects includes mechanisms of radiation action and cellular consequences. The discussion of radiobiological effects includes unique aspects of HZE particle effects, space flight findings, terrestrial findings, analysis of somatic radiation effects and effects on critical organs, and early and delayed effects. Other topics include the impact of the space flight environment, measurement of radiation exposure, establishing radiation protection limits, limitations in establishing space-based radiation exposure limits, radiation protection measures, and recommendations. PMID:11541474

  5. Involved-Lesion Radiation Therapy After Chemotherapy in Limited-Stage Head-and-Neck Diffuse Large B Cell Lymphoma

    SciTech Connect

    Yu, Jeong Il; Nam, Heerim; Ahn, Yong Chan; Kim, Won Seog; Park, Keunchil; Kim, Seok Jin

    2010-10-01

    Purpose: To report treatment outcomes after combined-modality therapy in patients with Stage I/II head-and-neck (HN) diffuse large B cell lymphoma (DLBL). Methods and Materials: Eighty-six eligible patients received sequential chemotherapy and involved-lesion radiation therapy from 1995 to 2006. After a median of four cycles of CHOP (cyclophosphamide, doxorubicin, vincristine, and prednisone) or rituximab-plus-CHOP chemotherapy, a median of 41.4 Gy was delivered to the known initial gross lesion with adequate margin (2 to 3 cm). Results: After a median follow-up of 57 months, eight treatment failures were observed: distant metastasis in 8 patients; and locoregional failure in 4 patients. Among the 4 patients with locoregional failure, 3 presented with in-field failures, and 1 both in-field and out-of-field failure (contralateral neck). Rates of overall survival (OS) and freedom from progression (FFP) at 10 years were 74.1% and 88.9%, respectively. There was no severe side effect except 1 patient with Grade 3 mucositis during and after completion of radiation therapy. Multivariate analyses showed that absence of B symptom (p = 0.022) and normal lactate dehydrogenase (p = 0.017) were related to favorable OS, age >60 years (p = 0.033) was related to favorable FFP, and international prognostic index of 0 or 1 was related to favorable OS (p = 0.003) and FFP (p = 0.03). Conclusion: This study demonstrated that patients with Stage I/II HN DLBL did not need whole-neck irradiation. Involved-lesion radiation therapy might reduce radiation toxicity with favorable treatment results.

  6. The Impact of Buoyancy and Flame Structure on Soot, Radiation and NOx Emissions from a Turbulent Diffusion Flame

    NASA Technical Reports Server (NTRS)

    Kennedy, I. M.; Kollman, W.; VanderWal, R. L.

    1999-01-01

    It is hypothesized that the spatial structure of a turbulent diffusion flame plays an important role in determining the emissions of radiative energy, soot and NO, from a combustor. This structure, manifested in the two point statistics, is influenced by buoyancy. Radiation, soot and NOx emissions are the cumulative result of processes that occur throughout a flame. For example, radiation fluxes along a line of sight can be found from summing up the contributions from sources in individual pockets of hot soot that emit, and from sinks in cold soot that absorb. Soot and NOx are both the results of slow chemistry and are not equilibrium products. The time that is available for production and burnout is crucial in determining the eventual emissions of these pollutants. Turbulence models generally rely on a single point closure of the appropriate time averaged equations. Hence, spatial information is lost and needs to be modeled using solution variables such as turbulence kinetic energy and dissipation rate, often with the assumption of isotropy. However, buoyancy can affect the physical structure of turbulent flames and can change the spatial extent of soot bearing regions. Theoretical comparisons with models are best done in the limit of infinite Froude number because the inclusion of buoyancy in flow models introduces significant uncertainties. Hence, LII measurements of soot, measurements of radiation fluxes from soot, Particle Imaging Velocimetry (PIV) of the flow field and measurements of post flame NOX will be carried out on the NASA Lewis 2.2 sec drop tower and eventually on the parabolic flight aircraft. The drop rig will be a modified version of a unit that has been successfully used at Lewis in the past.

  7. Diffuse sky radiation influences the relationship between canopy PRI and shadow fraction

    NASA Astrophysics Data System (ADS)

    Mõttus, Matti; Takala, Tuure L. H.; Stenberg, Pauline; Knyazikhin, Yuri; Yang, Bin; Nilson, Tiit

    2015-07-01

    The Photochemical Reflectance Index (PRI) of green leaves is an indicator of photosynthetic downregulation: when the photosynthetic apparatus is close to the saturation limit, PRI becomes dependent on light conditions. Therefore, by measuring the PRI of leaves under different local irradiance conditions, it should be possible to determine the saturation level of the leaves and obtain information on the light use efficiency (LUE) of a vegetation canopy. The dependence of PRI on the ratio of sunlit to shaded foliage (quantified by the canopy shadow fraction) in the field of view of an instrument has been used to remotely measure canopy LUE on clear days. However, besides photosynthetic downregulation, the dependence of canopy PRI on shadow fraction is affected by the blue sky radiation caused by scattering in the atmosphere. To quantify this effect on remotely sensed PRI, we present the underlying definitions relating leaf and canopy PRI and perform the required calculations for typical midsummer conditions in Central Finland. We demonstrate that the effect of blue sky radiation on the variation of PRI with canopy shadow fraction is similar in shape and magnitude to that of LUE variations reported in literature.

  8. A Radiation Chemistry Code Based on the Green's Function of the Diffusion Equation

    NASA Technical Reports Server (NTRS)

    Plante, Ianik; Wu, Honglu

    2014-01-01

    Stochastic radiation track structure codes are of great interest for space radiation studies and hadron therapy in medicine. These codes are used for a many purposes, notably for microdosimetry and DNA damage studies. In the last two decades, they were also used with the Independent Reaction Times (IRT) method in the simulation of chemical reactions, to calculate the yield of various radiolytic species produced during the radiolysis of water and in chemical dosimeters. Recently, we have developed a Green's function based code to simulate reversible chemical reactions with an intermediate state, which yielded results in excellent agreement with those obtained by using the IRT method. This code was also used to simulate and the interaction of particles with membrane receptors. We are in the process of including this program for use with the Monte-Carlo track structure code Relativistic Ion Tracks (RITRACKS). This recent addition should greatly expand the capabilities of RITRACKS, notably to simulate DNA damage by both the direct and indirect effect.

  9. A Multigroup diffusion solver using pseudo transient continuation for a radiation-hydrodynamic code with patch-based AMR

    SciTech Connect

    Shestakov, A I; Offner, S R

    2006-09-21

    We present a scheme to solve the nonlinear multigroup radiation diffusion (MGD) equations. The method is incorporated into a massively parallel, multidimensional, Eulerian radiation-hydrodynamic code with adaptive mesh refinement (AMR). The patch-based AMR algorithm refines in both space and time creating a hierarchy of levels, coarsest to finest. The physics modules are time-advanced using operator splitting. On each level, separate 'level-solve' packages advance the modules. Our multigroup level-solve adapts an implicit procedure which leads to a two-step iterative scheme that alternates between elliptic solves for each group with intra-cell group coupling. For robustness, we introduce pseudo transient continuation ({Psi}tc). We analyze the magnitude of the {Psi}tc parameter to ensure positivity of the resulting linear system, diagonal dominance and convergence of the two-step scheme. For AMR, a level defines a subdomain for refinement. For diffusive processes such as MGD, the refined level uses Dirichet boundary data at the coarse-fine interface and the data is derived from the coarse level solution. After advancing on the fine level, an additional procedure, the sync-solve (SS), is required in order to enforce conservation. The MGD SS reduces to an elliptic solve on a combined grid for a system of G equations, where G is the number of groups. We adapt the 'partial temperature' scheme for the SS; hence, we reuse the infrastructure developed for scalar equations. Results are presented. We consider a multigroup test problem with a known analytic solution. We demonstrate utility of {Psi}tc by running with increasingly larger timesteps. Lastly, we simulate the sudden release of energy Y inside an Al sphere (r = 15 cm) suspended in air at STP. For Y = 11 kT, we find that gray radiation diffusion and MGD produce similar results. However, if Y = 1 MT, the two packages yield different results. Our large Y simulation contradicts a long-standing theory and demonstrates the inadequacy of gray diffusion.

  10. Diffusion Tensor Imaging of Normal-Appearing White Matter as Biomarker for Radiation-Induced Late Delayed Cognitive Decline

    SciTech Connect

    Chapman, Christopher H.; Nagesh, Vijaya; Sundgren, Pia C.; Buchtel, Henry; Chenevert, Thomas L.; Junck, Larry; Lawrence, Theodore S.; Tsien, Christina I.; Cao, Yue

    2012-04-01

    Purpose: To determine whether early assessment of cerebral white matter degradation can predict late delayed cognitive decline after radiotherapy (RT). Methods and Materials: Ten patients undergoing conformal fractionated brain RT participated in a prospective diffusion tensor magnetic resonance imaging study. Magnetic resonance imaging studies were acquired before RT, at 3 and 6 weeks during RT, and 10, 30, and 78 weeks after starting RT. The diffusivity variables in the parahippocampal cingulum bundle and temporal lobe white matter were computed. A quality-of-life survey and neurocognitive function tests were administered before and after RT at the magnetic resonance imaging follow-up visits. Results: In both structures, longitudinal diffusivity ({lambda}{sub Double-Vertical-Line }) decreased and perpendicular diffusivity ({lambda}{sub Up-Tack }) increased after RT, with early changes correlating to later changes (p < .05). The radiation dose correlated with an increase in cingulum {lambda}{sub Up-Tack} at 3 weeks, and patients with >50% of cingula volume receiving >12 Gy had a greater increase in {lambda}{sub Up-Tack} at 3 and 6 weeks (p < .05). The post-RT changes in verbal recall scores correlated linearly with the late changes in cingulum {lambda}{sub Double-Vertical-Line} (30 weeks, p < .02). Using receiver operating characteristic curves, early cingulum {lambda}{sub Double-Vertical-Line} changes predicted for post-RT changes in verbal recall scores (3 and 6 weeks, p < .05). The neurocognitive test scores correlated significantly with the quality-of-life survey results. Conclusions: The correlation between early diffusivity changes in the parahippocampal cingulum and the late decline in verbal recall suggests that diffusion tensor imaging might be useful as a biomarker for predicting late delayed cognitive decline.

  11. Diffusion tensor imaging of optic nerve and optic radiation in primary chronic angle-closure glaucoma using 3T magnetic resonance imaging

    PubMed Central

    Zhang, Qiu-Juan; Wang, Dong; Bai, Zhi-Lan; Ren, Bai-Chao; Li, Xiao-Hui

    2015-01-01

    AIM To evaluate the value of quantitative diffusion tensor imaging (DTI) in assessing the axonal and myelin damage of the optic nerves and optic radiations in patients with chronic primary angle-closure glaucoma (PACG) by using high-field magnetic resonance (MR) imaging (3T). METHODS Twenty patients with bilateral chronic PACG and twenty age- and sex matched disease-free control subjects were enrolled. Conventional MRI and DTI were performed on all subjects using 3T MR scanner. Mean diffusivity (MD), fractional anisotropy (FA), axial diffusivities (AD) and radial diffusivities (RD) of each optic nerve and each optic radiation were measured by using post-processing software of DTI studio 2.3, and then compared between left eyes and right eyes and between patients group and control group. The paired-sample t- test were used. RESULTS There was no abnormality in the shape and signal intensity of the optic nerves and optic radiations in patients group and control group on the conventional MRI. No significant differences were observed in the FA, MD, AD and RD between the right and left optic nerves and optic radiations within patients group and control group (P>0.05). The optic nerves and optic radiations of patients with chronic PACG, as compared with control subjects, had significantly higher MD, AD, RD and significantly lower FA (P<0.05). CONCLUSION The diffusivity of optic nerves and optic radiations in chronic PACG group showed abnormal and diffusivity parameters could be used markers of axonal and myelin injury in glaucoma. PMID:26558212

  12. The implications of the COBE diffuse microwave radiation results for cosmic strings

    NASA Technical Reports Server (NTRS)

    Bennett, David P.; Stebbins, Albert; Bouchet, Francois R.

    1992-01-01

    We compare the anisotropies in the cosmic microwave background radiation measured by the COBE experiment to those predicted by cosmic string theories. We use an analytic model for the Delta T/T power spectrum that is based on our previous numerical simulations of strings, under the assumption that cosmic strings are the sole source of the measured anisotropy. This implies a value for the string mass per unit length of 1.5 +/- 0.5 x 10 exp -6 C-squared/G. This is within the range of values required for cosmic strings to successfully seed the formation of large-scale structures in the universe. These results clearly encourage further studies of Delta T/T and large-scale structure in the cosmic string model.

  13. Non-diffusive resonant acceleration of electrons in the radiation belts

    NASA Astrophysics Data System (ADS)

    Artemyev, A. V.; Krasnoselskikh, V. V.; Agapitov, O. V.; Mourenas, D.; Rolland, G.

    2012-12-01

    We describe a mechanism of resonant electron acceleration by oblique high-amplitude whistler waves under conditions typical for the Earth radiation belts. We use statistics of spacecraft observations of whistlers in the Earth radiation belts to obtain the dependence of the angle ? between the wave-normal and the background magnetic field on magnetic latitude ?. According to this statistics, the angle ? already approaches the resonance cone at ? ˜15° and remains close to it up to ? ˜30°-40° on the dayside. The parallel component of the electrostatic field of whistler waves often increases around ? ˜15° up to one hundred of mV/m. We show that due to this increase of the electric field, the whistler waves can trap electrons into the potential well via wave particle resonant interaction corresponding to Landau resonance. Trapped electrons then move with the wave to higher latitudes where they escape from the resonance. Strong acceleration is favored by adiabatic invariance along the increasing magnetic field, which continuously transfers the parallel energy gained to perpendicular energy, allowing resonance to be reached and maintained. The concomitant increase of the wave phase velocity allows for even stronger relative acceleration at low energy <50keV. Each trapping-escape event of electrons of ˜10keV to 100 keV results in an energy gain of up to 100 keV in the inhomogeneous magnetic field of the Earth dipole. For electrons with initial energy below 100 keV, such rapid acceleration should hasten their drop into the loss-cone and their precipitation into the atmosphere. We discuss the role of the considered mechanism in the eventual formation of a trapped distribution of relativistic electrons for initial energies larger than 100 keV and in microbursts precipitations of lower energy particles.

  14. Adaptors for radiation detectors

    SciTech Connect

    Livesay, Ronald Jason

    2014-04-22

    Described herein are adaptors and other devices for radiation detectors that can be used to make accurate spectral measurements of both small and large bulk sources of radioactivity, such as building structures, soils, vessels, large equipment, and liquid bodies. Some exemplary devices comprise an adaptor for a radiation detector, wherein the adaptor can be configured to collimate radiation passing through the adapter from an external radiation source to the radiation detector and the adaptor can be configured to enclose a radiation source within the adapter to allow the radiation detector to measure radiation emitted from the enclosed radiation source.

  15. Adaptors for radiation detectors

    DOEpatents

    Livesay, Ronald Jason

    2015-07-28

    Described herein are adaptors and other devices for radiation detectors that can be used to make accurate spectral measurements of both small and large bulk sources of radioactivity, such as building structures, soils, vessels, large equipment, and liquid bodies. Some exemplary devices comprise an adaptor for a radiation detector, wherein the adaptor can be configured to collimate radiation passing through the adapter from an external radiation source to the radiation detector and the adaptor can be configured to enclose a radiation source within the adapter to allow the radiation detector to measure radiation emitted from the enclosed radiation source.

  16. Radiation dosimeters

    DOEpatents

    Hoelsher, James W. (Pullman, WA); Hegland, Joel E. (Pullman, WA); Braunlich, Peter F. (Pullman, WA); Tetzlaff, Wolfgang (Pullman, WA)

    1992-01-01

    Radiation dosimeters and dosimeter badges. The dosimeter badges include first and second parts which are connected to join using a securement to produce a sealed area in which at least one dosimeter is held and protected. The badge parts are separated to expose the dosimeters to a stimulating laser beam used to read dose exposure information therefrom. The badge is constructed to allow automated disassembly and reassembly in a uniquely fitting relationship. An electronic memory is included to provide calibration and identification information used during reading of the dosimeter. Dosimeter mounts which reduce thermal heating requirements are shown. Dosimeter constructions and production methods using thin substrates and phosphor binder-layers applied thereto are also taught.

  17. Radiation Insulation

    NASA Technical Reports Server (NTRS)

    1993-01-01

    An aluminized polymer film is a highly effective radiation barrier for both manned and unmanned spacecraft. Variations of this space-devised material are also used as an energy conservation technique for homes and offices. One commercial company, Tech 2000 (formerly Buckeye Radiant Barrier), markets 'Super R' Radiant Barrier, which finds its origins in the Apollo Mission programs. The material is placed between wall studs and exterior facing before siding or in new roof installation, between roof support and roof sheathing. Successful retrofit installations have included schools and shrink wrap ovens. The radiant barrier blocks 95 percent of radiant energy, thus retaining summer heat and blocking winter cold. Suppliers claim utility bill reductions of 20 percent or more.

  18. Radiation Safety Manual Prepared by

    E-print Network

    Johnson, Eric E.

    Radiation Safety Manual Prepared by University Radiation Safety Committee in coordination with NMSU.........................................................................3 Radiation Safety Officer ....................................................................................................... 3 University Radiation Safety Committee

  19. Simulated effects of changes in direct and diffuse radiation on canopy scale isoprene emissions from vegetation following volcanic eruptions

    NASA Astrophysics Data System (ADS)

    Wilton, D. J.; Hewitt, C. N.; Beerling, D. J.

    2011-03-01

    Volcanic eruptions can alter the quality of incoming solar irradiance reaching the Earth's surface thereby influencing the interactions between vegetation and the Earth system. Isoprene (C5H8) is a biogenic volatile organic compound emitted from leaves at a rate strongly dependent on the received flux of photosynthetically radiation radiation (PAR). We investigated the potential for volcanic eruptions to change the isoprene flux from terrestrial vegetation using canopy-scale isoprene emission simulations that vary either the relative or absolute amount of diffuse (Idiff) and direct (Idir) PAR. According to our simulations, if the total amount of PAR remains constant while the proportion of Idiff increases, canopy-scale isoprene emissions increase. This effect increases as leaf area index increases. Simulating a~decrease in the total amount of PAR, and a corresponding increase in Idiff fraction, as measured during the 1992 Pinatubo eruption, decreases daily total canopy-scale isoprene emissions from terrestrial vegetation by 17-19% (for leaf area indices of 6 and 2, respectively). These effects have not previously been realized or quantified. Better capturing the effects of volcanic eruptions (and other major perturbations to the atmospheric aerosol content) on isoprene emissions from the terrestrial biosphere, and hence on the chemistry of the atmosphere, therefore requires inclusion of the effects of aerosols they produce on climate and total PAR and the Idiff/Idir ratio.

  20. Radiation from Relativistic Jets

    NASA Technical Reports Server (NTRS)

    Nishikawa, K.-I.; Mizuno, Y.; Hardee, P.; Sol, H.; Medvedev, M.; Zhang, B.; Nordlund, A.; Frederiksen, J. T.; Fishman, G. J.; Preece, R.

    2008-01-01

    Nonthermal radiation observed from astrophysical systems containing relativistic jets and shocks, e.g., gamma-ray bursts (GRBs), active galactic nuclei (AGNs), and Galactic microquasar systems usually have power-law emission spectra. Recent PIC simulations of relativistic electron-ion (electron-positron) jets injected into a stationary medium show that particle acceleration occurs within the downstream jet. In the presence of relativistic jets, instabilities such as the Buneman instability, other two-streaming instability, and the Weibel (filamentation) instability create collisionless shocks, which are responsible for particle (electron, positron, and ion) acceleration. The simulation results show that the Weibel instability is responsible for generating and amplifying highly nonuniform, small-scale magnetic fields. These magnetic fields contribute to the electron's transverse deflection behind the jet head. The 'jitter' radiation from deflected electrons in small-scale magnetic fields has different properties than synchrotron radiation which is calculated in a uniform magnetic field. This jitter radiation, a case of diffusive synchrotron radiation, may be important to understand the complex time evolution and/or spectral structure in gamma-ray bursts, relativistic jets, and supernova remnants.

  1. Modeling radiation belt radial diffusion in ULF wave fields: 2. Estimating rates of radial diffusion using combined MHD and particle codes

    NASA Astrophysics Data System (ADS)

    Huang, Chia-Lin; Spence, Harlan E.; Hudson, Mary K.; Elkington, Scot R.

    2010-06-01

    Quantifying radial transport of radiation belt electrons in ULF wave fields is essential for understanding the variability of the trapped relativistic electrons. To estimate the radial diffusion coefficients (DLL), we follow MeV electrons in realistic magnetospheric configurations and wave fields calculated from a global MHD code. We create idealized pressure-driven MHD simulations for controlled solar wind velocities (hereafter referred to as pressure-driven Vx simulations) with ULF waves that are comparable to GOES data under similar conditions, by driving the MHD code with synthetic pressure profiles that mimic the pressure variations of a particular solar wind velocity. The ULF wave amplitude, in both magnetic and electric fields, increases at larger radial distance and during intervals with higher solar wind velocity and pressure fluctuations. To calculate DLL as a function of solar wind velocity (Vx = 400 and 600 km/s), we follow 90 degree pitch angle electrons in magnetic and electric fields of the pressure-driven Vx simulations. DLL is higher at larger radial distance and for the case with higher solar wind velocity and pressure variations. Our simulated DLL values are relatively small compared to previous studies which used larger wave fields in their estimations. For comparison, we scale our DLL values to match the wave amplitudes of the previous studies with those of the idealized MHD simulations. After the scaling, our DLL values for Vx = 600 km/s are comparable to the DLL values derived from Polar measurements during nonstorm intervals. This demonstrates the use of MHD models to quantify the effect of pressure-driven ULF waves on radiation belt electrons and thus to differentiate the radial diffusive process from other mechanisms.

  2. Influence of diffusion and non-local radiation transport on the laser amplification of a He-Ne ring laser gyro

    NASA Astrophysics Data System (ADS)

    Macé, J. S.; Maynard, G.; Virdis, A.

    2014-08-01

    The influence of the transport of excited atoms on the laser amplification inside the positive column of a low-pressure He-Ne dc discharge of a ring laser gyro has been studied. Both non-radiative diffusion and the contribution of radiation transport have been considered. The transport induced by the radiation trapping has been determined using a Monte-Carlo simulation, taking into account an isotopic structure for the neon and the collisional line broadening in presence of helium. The transfer matrix for spatial redistribution has been calculated in a cylindrical geometry and has been included in a one-dimensional collisional-radiative model (1D-CRM). This 1D-CRM has been used to determine the laser gain within a two levels approach. Our results show that radiative and non-radiative diffusions have a significant contribution on the radial profile of the gain of the main oscillating mode, both in the unsaturated and saturated regimes. This contribution is strongly dependent on the ratio between the transverse sizes of the laser and of the plasma.

  3. Solar radiation resource assessment

    SciTech Connect

    Not Available

    1990-11-01

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

  4. Solar radiation on inclined surfaces

    NASA Astrophysics Data System (ADS)

    1980-05-01

    Mean monthly values of daily shortwave radiation on inclined surfaces are presented for 13 locations in India. Values of direct, diffuse sky, reflected, and total shortwave radiation incident on an inclined surface are given for 9 slope angles (measured from the horizontal) and 8 aspects. All the data are computed using measured values of the total shortwave radiation on a horizontal surface according to the techniques described. Maximum and minimum values of direct solar radiation during each month are underlined and marked by asterisk respectively. Actual and potential users of radiation data, particularly those in the fields of agriculture, horticulture, forestry, architecture, heating and ventilating engineering, and photovoltaic systems, it is hoped, would find this publication useful in planning and designing of solar radiation devices.

  5. Spectroscopy of diffuse light in dust clouds. Scattered light and the solar neighbourhood radiation field

    NASA Astrophysics Data System (ADS)

    Lehtinen, K.; Mattila, K.

    2013-01-01

    Context. The optical surface brightness of dark nebulae is mainly due to scattering of integrated starlight by classical dust grains. It contains information on the impinging interstellar radiation field, cloud structure, and grain scattering properties. We have obtained spectra of the scattered light from 3500 to 9000 Å in two globules, the Thumbprint Nebula and DC 303.8-14.2. Aims. We use observations of the scattered light to study the impinging integrated starlight spectrum as well as the scattered H? and other line emissions from all over the sky. We search also for the presence of other than scattered light in the two globules. Methods. We obtained long-slit spectra encompassing the whole globule plus adjacent sky in a one-slit setting, thus enabling efficient elimination of airglow and other foreground sky components. We calculated synthetic integrated starlight spectra for the solar neighbourhood using HIPPARCOS-based stellar distributions and the spectral library of Pickles. Results. Spectra are presented separately for the bright rims and dark cores of the globules. The continuum spectral energy distributions and absorption line spectra can be well modelled with the synthetic integrated starlight spectra. Emission lines of H? +[N II], H?, and [S II] are detected and are interpreted in terms of scattered light plus an in situ warm ionized medium component behind the globules. We detected an excess of emission over the wavelength range 5200-8000 Å in DC 303.8-14.2 but the nature of this emission remains open. Based on observations collected at the European Southern Observatory, Chile, under programme ESO No. 073.C-0239(A). Appendix A is available in electronic form at http://www.aanda.org.

  6. Uncertainty analysis of diffuse-gray radiation enclosure problems: A hypersensitive case study

    NASA Technical Reports Server (NTRS)

    Taylor, Robert P.; Luck, Rogelio; Hodge, B. K.; Steele, W. Glenn

    1993-01-01

    An uncertainty analysis of diffuse-gray enclosure problems is presented. The genesis was a diffuse-gray enclosure problem which proved to be hypersensitive to the specification of view factors. This genesis is discussed in some detail. The uncertainty analysis is presented for the general diffuse-gray enclosure problem and applied to the hypersensitive case study. It was found that the hypersensitivity could be greatly reduced by enforcing both closure and reciprocity for the view factors. The effects of uncertainties in the surface emissivities and temperatures are also investigated.

  7. Solar radiation modelling

    NASA Astrophysics Data System (ADS)

    Zakšek, Klemen; Podobnikar, Tomaž; Oštir, Krištof

    2005-03-01

    The Sun is the main energy source of the life on the Earth. Thus, solar radiation energy data and models are important for many areas of research and applications. Many parameters influence the amount of solar energy at a particular standing point of the Earth's surface; therefore, many solar radiation models were produced in the last few years. Solar radiation energy depends mostly on incidence angle, which is defined by astronomical and surface parameters. Our solar radiation model is based on defining incidence angle by computing normal-to-the-surface tangent plane and direction of the Sun. If a part of the surface is in the shadow, it receives lesser energy than sunny areas. That is why shadow determination is an important part of the model. The sky is usually not completely clear, so meteorological parameters had to be integrated into the model. Meteorological model distinguishes among direct and diffuse Sun radiation. The model was tested and implemented for the whole Slovenia and it was also compared with previous studies. Case study surface data were calculated from the DEM with a 25 m resolution. The astronomical data, which were required for virtual Sun motion simulation around the Earth, were derived from the astronomical almanac. Meteorological data were acquired from observed mean values on 24 meteorological stations between 1961 and 1990. All calculations were made for hours and decades and finally, the annual quasiglobal radiation energy, which is the energy received by inclined plane from the Sun in one year, was calculated from the sum of all the energies of all the decades.

  8. Simulation of Infrared Laser Heating of Silica Using Heat Conduction and Multifrequency Radiation Diffusion Equations Adapted for Homogeneous Refractive Lossy Media

    SciTech Connect

    Shestakov, A I; Matthews, M J; Vignes, R M; Stolken, J S

    2010-10-28

    Localized, transient heating of materials using micro-scale, highly absorbing laser light has been used in many industries to anneal, melt and ablate material with high precision. Accurate modeling of the relative contributions of conductive, convective and radiative losses as a function of laser parameters is essential to optimizing micro-scale laser processing of materials. In bulk semi-transparent materials such as silicate glass melts, radiation transport is known to play a significantly larger role as the temperature increases. Conventionally, radiation is treated in the frequency-averaged diffusive limit (Rosseland approximation). However, the role and proper treatment of radiative processes under rapidly heated, high thermal gradient conditions, often created through laser-matter interactions, is at present not clear. Starting from the radiation transport equation for homogeneous, refractive lossy media, they derive the corresponding time-dependent multi-frequency diffusion equations. Zeroth and first moments of the transport equation couple the energy density, flux and pressure tensor. The system is closed by neglecting the temporal derivative of the flux and replacing the pressure tensor by its diagonal analogue. The radiation equations are coupled to a diffusion equation for the matter temperature. They are interested in modeling infrared laser heating of silica over sub-millimeter length scales, and at possibly rapid rates. Hence, in contrast to related work, they retain the temporal derivative of the radiation field. They derive boundary conditions at a planar air-silica interface taking account of reflectivities obtained from the Fresnel relations that include absorption. The effect of a temperature-dependent absorption index is explored through construction of a multi-phonon dielectric function that includes mode dispersion. The spectral dimension is discretized into a finite number of intervals yielding a system of multigroup diffusion equations. Simulations are presented. To demonstrate the bulk heat loss due to radiation and the effect of the radiation's temporal derivative, they model cooling of a silica slab, initially at 2500 K, for 10 s. Retaining the derivative enables correctly modeling the loss of photons initially present in the slab. Other simulations model irradiating silica discs (of approximately 5 mm radii and thickness) with a CO2 laser: {lambda} = 10.59 and 4.6 um, Gaussian profile, r{sub 0} = 0.5 mm for 1/e decay. By surrounding the disks in room-temperature air, they make use of the boundary conditions described above.

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

    SciTech Connect

    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.

  10. Radiation and People

    ERIC Educational Resources Information Center

    Freilich, Florence G.

    1970-01-01

    Describes the development of radiation as a tool of medicine. Includes topics on history of radiation, electromagnetic spectrum, X-ray tubes, high energy machines, radioactive sources, artificial radioactivity, radioactive scanning, units, present radiation background, and effect of radiation on living tissue. (DS)

  11. Dynamics of radiating fluids

    SciTech Connect

    Mihalas, D.; Weaver, R.

    1982-01-01

    The purpose of this paper is to give an overview of the role of radiation in the transport of energy and momentum in a combined matter-radiation fluid. The transport equation for a moving radiating fluid is presented in both a fully Eulerian and a fully Lagrangian formulation, along with conservation equations describing the dynamics of the fluid. Special attention is paid to the problem of deriving equations that are mutually consistent in each frame, and between frames, to 0(v/c). A detailed analysis is made to show that in situations of broad interest, terms that are formally of 0(v/c) actually dominate the solution, demonstrating that it is essential (1) to pay scrupulous attention to the question of the frame dependence in formulating the equations, and (2) to solve the equations to 0(v/c) in quite general circumstances. These points are illustrated in the context of the nonequilibrium radiation diffusion limit, and a sketch of how the Lagrangian equations are to be solved is presented.

  12. Magnetic field line curvature induced pitch angle diffusion in the radiation belts

    NASA Astrophysics Data System (ADS)

    Young, S. L.; Denton, R. E.; Anderson, B. J.; Hudson, M. K.

    2003-12-01

    We derive a diffusion equation to model the pitch angle dynamics of a trapped charged particle population strongly influenced by magnetic field line curvature. The equation is based on a recently published, empirical model for pitch angle scattering of single particles. In order to examine the predictions of this equation in the inner magnetosphere we define a diffusion time. Often the purely exponential decay time of the lowest eigenfunction is used to characterize the decay of a population. However, because our equation is singular for 90o equatorial pitch angles there is no physically meaningful lowest order eigenfunction. We define the diffusion time as the time it takes for a distribution to decay to half its initial density. Because this depends on the initial distribution we examine the decay of three distributions that vary in the degree to which they are peaked about the 90o equatorial pitch angle. We calculate diffusion times for these distributions as a function of Dst, season, and UT (season and UT being proxies for the angle between the dipole axis and the solar wind) using Tsyganenko 01 magnetic field model. We show that the diffusion is strongly dependent on both the initial distribution and Dst, and examine the weaker dependence on the direction of the dipole axis relative to the solar wind. Using the results of these calculations we estimate thresholds in parameter space for which the particle populations will decay in 10 hours for electrons, protons, and O+8 ions. To demonstrate the sharpness of these thresholds we also estimate the threshold for decay in 1000 hours for protons.

  13. Trends of the sunshine duration and diffuse radiation percentage on sunny days in urban agglomerations of China during 1960-2005.

    PubMed

    Fu, Chuanbo; Dan, Li; Chen, Youlong; Tang, Jiaxiang

    2015-08-01

    The long-term observational data of sunshine duration (SD) and diffuse radiation percentage (defined as diffuse solar radiation/total solar radiation, DRP) on sunny days during 1960-2005 were analyzed in 7 urban agglomerations and the whole of China. The results show that the sunny sunshine duration (SSD) has decreased significantly except at a few stations over northwestern China in the past 46years. An obvious decrease of the SSD is found in eastern China, with the trend coefficients lower than -0.8. Accompanied by the SSD decline, the sunny diffuse radiation percentage (SDRP) in most stations shows obvious increasing trends during the 46years. The averaged SDRP over China has increased 2.33% per decade, while the averaged SSD shows a decrease of -0.13hr/day per decade. The correlation coefficient between SDRP and SSD is -0.88. SSD decreased over urban agglomerations (small to large city clusters) in the past 46years, especially in large cities and medium cities, due to the strong anthropogenic activities and air pollution represented by aerosol option depth (AOD) and tropospheric column NO2 (TroNO2). On the regional scale, SSD has an opposite trend from SDRP during 1960 to 2005, and the variation trends of regional mean values of SSD and SDRP in southeastern China are more pronounced than those in northwestern China. PMID:26257363

  14. SAS-2 observations of the diffuse gamma radiation in the galactic latitude interval 10 deg absolute b or equal to 90 deg

    NASA Technical Reports Server (NTRS)

    Fichtel, C. E.; Hartman, R. C.; Kniffen, D. A.; Thompson, D. J.; Oegelman, H. B.; Oezel, M. E.; Tuemer, T.

    1977-01-01

    An analysis of all of the second small astronomy satellite gamma-ray data for galactic latitudes with the absolute value of b 10 deg has shown that the intensity varies with galactic latitude, being larger near 10 deg than 90 deg. For energies above 100 MeV the gamma-ray data are consistent with a latitude distribution of the form I(b) = C sub 1 + C sub 2/sin b, with the second term being dominant. This result suggests that the radiation above 100 MeV is coming largely from local regions of the galactic disk. Between 35 and 100 MeV, a similar equation is also a good representation of the data, but here the two terms are comparable. These results indicate that the diffuse radiation above 35 MeV consists of two parts, one with a relatively hard galactic component and the other an isotropic, steep spectral component which extrapolates back well to the low energy diffuse radiation. The steepness of the diffuse isotropic component places significant constraints on possible theoretical models of this radiation.

  15. Hazard calculations of diffuse reflected laser radiation for the SELENE program

    NASA Technical Reports Server (NTRS)

    Miner, Gilda A.; Babb, Phillip D.

    1993-01-01

    The hazards from diffuse laser light reflections off water clouds, ice clouds, and fog and from possible specular reflections off ice clouds were assessed with the American National Standards (ANSI Z136.1-1986) for the free-electron-laser parameters under consideration for the Segmented Efficient Laser Emission for Non-Nuclear Electricity (SELENE) Program. Diffuse laser reflection hazards exist for water cloud surfaces less than 722 m in altitude and ice cloud surfaces less than 850 m in altitude. Specular reflections from ice crystals in cirrus clouds are not probable; however, any specular reflection is a hazard to ground observers. The hazard to the laser operators and any ground observers during heavy fog conditions is of such significant magnitude that the laser should not be operated in fog.

  16. SAS-2 observations of celestial diffuse gamma radiation above 30 MeV

    NASA Technical Reports Server (NTRS)

    Thompson, D. J.; Fichtel, C. E.; Kniffen, D. A.; Hartman, R. C.

    1974-01-01

    The small astronomy satellite, SAS-2, used a 32-deck magnetic core digitized spark chamber to study gamma rays with energies above 30 MeV. Data for four regions of the sky away from the galactic plane were analyzed. These regions show a finite, diffuse flux of gamma rays with a steep energy spectrum, and the flux is uniform over all the regions. Represented by a power law, the differential energy spectrum shows an index of 2.5 + or - 0.4. The steep SAS-2 spectrum and the lower energy data are reasonably consistent with a neutral pion gamma-ray spectrum which was red-shifted (such as that proposed by some cosmological theories). It is concluded that the diffuse celestial gamma ray spectrum observed presents the possibility of cosmological studies and possible evidence for a residual cosmic ray density, and supports the galactic superclusters of matter and antimatter remaining from baryon-symmetric big bang.

  17. Relationships between diffuse reflectance and vegetation canopy variables based on the radiative transfer theory

    NASA Technical Reports Server (NTRS)

    Park, J. K.; Deering, D. W.

    1981-01-01

    Out of the lengthy original expression of the diffuse reflectance formula, simple working equations were derived by employing characteristic parameters, which are independent of the canopy coverage and identifiable by field observations. The typical asymptotic nature of reflectance data that is usually observed in biomass studies was clearly explained. The usefulness of the simplified equations was demonstrated by the exceptionally close fit of the theoretical curves to two separately acquired data sets for alfalfa and shortgrass prairie canopies.

  18. Energetic electrons at Uranus: Bimodal diffusion in a satellite limited radiation belt

    SciTech Connect

    Selesnick, R.S.; Stone, E.C. )

    1991-04-01

    The Voyager 2 cosmic ray experiment observed intense electron fluxes in the middle magnetosphere of Uranus. High counting rates in several of the solid-state detectors precluded in the normal multiple coincidence analysis used for cosmic ray observations, and the authors have therefore performed laboratory measurements of the single-detector response to electrons. These calibrations allow a deconvolution from the counting rate data of the electron energy spectrum between energies of about 0.7 and 2.5 MeV. They present model fits to the differential intensity spectra from observations between L values of 6 and 15. The spectra are well represented by power laws in kinetic energy with spectral indices between 5 and 7. The phase space density at fixed values of the first two adiabatic invariants generally increases with L, indicative of an external source. However, there are also local minima associated with the satellites Ariel and Umbriel, indicating either a local source or an effective source due to nonconservation of the first two adiabatic invariants. For electrons which mirror at the highest magnetic latitudes, the local minimum associated with Ariel is radically displaced from the minimum L of that satellite by {approximately}0.5. The latitude variation of the satellite absorption efficiency predicts that if satellite losses are replenished primarily by radial diffusion there should be an increasing pitch angle anisotropy with decreasing L. The uniformity in the observed anisotropy outside the absorption regions then suggests that it is maintained by pitch angle diffusion. The effective source due to pitch angle diffusion is insufficient to cause the phase space density minimum associated with Ariel. Model solutions of the simultaneous radial and pitch angle diffusion equation show that the displacement of the high-latitude Ariel signature is also consistent with a larger effective source.

  19. The diffuse far-ultraviolet cosmic background radiation field observed from the Space Shuttle

    NASA Technical Reports Server (NTRS)

    Murthy, J.; Henry, R. C.; Feldman, P. D.; Tennyson, P. D.

    1989-01-01

    The paper presents 17-A resolution spectra of the diffuse far-ultraviolet (1200-1700 A) cosmic background in eight regions of the sky obtained from the Johns Hopkins University UVX experiment aboard the Space Shuttle Columbia (STS-61C) in January 1986. A spectrally flat background is found with brightnesses between 100 and 700 + or - 200 photons/sq cm s sr A, with some evidence for spatial variations, but not for the high-intensity regions found by other experiments.

  20. Resonant and diffusive transport of relativistic electrons in Earth's radiation belts

    NASA Astrophysics Data System (ADS)

    Vassiliadis, Dimitris; Tornquist, Mattias; Shao, Xi; Koepke, Mark

    2012-10-01

    Electron transport at field-line resonances and cavity modes is a textbook case of adiabatic motion. Often however such structures are absent so particle scattering is modulated by interplanetary and internal disturbances featuring broadband spectra and resulting in diffusive transport. We discuss the types of relativistic electron transport occurring when FLR structures coexist with stochastic fields. First, test-particle simulations driven with power-law wave spectra are used to show that the diffusion coefficient is a function of the integrated wave power and the spectral index. Second, the excitation of an FLR by compressional-mode waves is simulated in a 2D box model. The combined fields of driver waves and the resonance are used to drive particle transport, and competition between resonant and diffusive scattering depends on driver amplitude and resonance dissipation. Third, global-magnetospheric MHD simulations driven with measured solar wind are used to reconstruct magnetic storm events. Solar wind variations often have near-power-law spectra, and produce low-frequency magnetospheric compressional fluctuations. These waves are used to drive guiding-center electron dynamics in the equatorial plane. Competition between modes of transport is a function of the wave amplitude, polarization, and spectral index; and of the decay rate of stationary resonances on the magnetospheric dayside and flanks. We discuss the fundamental transport types in each case.

  1. The diffuse galactic gamma radiation: The Compton contribution and component separation by energy interval and galactic coordinates

    NASA Technical Reports Server (NTRS)

    Kniffen, D. A.; Fichtel, C.

    1981-01-01

    The radiation to be expected from cosmic ray interactions with matter and photons was examined. Particular emphasis is placed on the Compton emission. Both the photon density in and near the visible region and that in the region are deduced from the estimates of the emission functions throughout the Galaxy. The blackbody radiation is also included in the estimate of the total Compton emission. The result suggests that the gamma ray Compton radiation from cosmic ray ineractions with galactic visible and infrared photons is substantially larger than previously believed.

  2. Diffuse far-ultraviolet cosmic background radiation field observed from the Space Shuttle

    SciTech Connect

    Murthy, J.; Henry, R.C.; Feldman, P.D.; Tennyson, P.D.

    1989-01-01

    The paper presents 17-A resolution spectra of the diffuse far-ultraviolet (1200-1700 A) cosmic background in eight regions of the sky obtained from the Johns Hopkins University UVX experiment aboard the Space Shuttle Columbia (STS-61C) in January 1986. A spectrally flat background is found with brightnesses between 100 and 700 + or - 200 photons/sq cm s sr A, with some evidence for spatial variations, but not for the high-intensity regions found by other experiments. 30 references.

  3. Guideline Implementation: Radiation Safety.

    PubMed

    Fencl, Jennifer L

    2015-12-01

    Because radiologic technology is used in a variety of perioperative procedures and settings, it is essential for perioperative RNs to be knowledgeable of the risks related to radiation and the ways to adequately protect patients and health care providers from unintended radiation exposure. The updated AORN "Guideline for radiation safety" provides guidance on preventing injury from ionizing radiation exposure during therapeutic, diagnostic, and interventional procedures. This article focuses on key points of the guideline to help perioperative personnel practice radiation safety. The key points address the requirements for an organization's radiation safety program, measures used to keep radiation exposure as low as reasonably achievable, proper handling and testing of radiation protection devices, and considerations for protecting employees and patients who are pregnant and who will be exposed to radiation. Perioperative RNs should review the complete guideline for additional information and for guidance when writing and updating policies and procedures. PMID:26616323

  4. Simulated effects of changes in direct and diffuse radiation on canopy scale isoprene emissions from vegetation following volcanic eruptions

    NASA Astrophysics Data System (ADS)

    Wilton, D. J.; Hewitt, C. N.; Beerling, D. J.

    2011-11-01

    Volcanic eruptions can alter the quality of incoming solar irradiance reaching the Earth's surface thereby influencing the interactions between vegetation and the Earth system. Isoprene (C5H8) is a biogenic volatile organic compound emitted from leaves at a rate that is strongly dependent on the received flux of photosynthetically active radiation (PAR). We used a theoretical approach to investigate the potential for volcanic eruptions to change the isoprene flux from terrestrial forests using canopy-scale isoprene emission simulations that vary either the relative or absolute amount of diffuse (Idiff) and direct (Idir) PAR. According to our simulations for a northern hardwood deciduous forest, if the total amount of PAR during summer remains constant while the proportion of Idiff increases, canopy-scale isoprene emissions increase. This effect increases as leaf area index (LAI) increases. Simulating a decrease in the total amount of PAR, and a corresponding increase in Idiff fraction, as measured during the 1992 Pinatubo eruption, changes daily total canopy-scale isoprene emissions from terrestrial vegetation in summertime by +2.8% and -1.4% for LAI of 6 and 2, respectively. These effects have not previously been realized or quantified. Better capturing the effects of volcanic eruptions (and other major perturbations to the atmospheric aerosol content) on isoprene emissions from the terrestrial biosphere, and hence on the chemistry of the atmosphere, therefore may require inclusion of the effects of aerosols they produce on climate and the quality of PAR.

  5. Introduction to radiation transport

    SciTech Connect

    Olson, G.L.

    1998-12-31

    This lecture will present time-dependent radiation transport where the radiation is coupled to a static medium, i.e., the material is not in motion. In reality, radiation exerts a pressure on the materials it propagates through and will accelerate the material in the direction of the radiation flow. This fully coupled problem with radiation transport and materials in motion is referred to as radiation-hydrodynamics (or in a shorthand notation: rad-hydro) and is beyond the scope of this lecture.

  6. Plutonium radiation surrogate

    DOEpatents

    Frank, Michael I. (Dublin, CA)

    2010-02-02

    A self-contained source of gamma-ray and neutron radiation suitable for use as a radiation surrogate for weapons-grade plutonium is described. The source generates a radiation spectrum similar to that of weapons-grade plutonium at 5% energy resolution between 59 and 2614 keV, but contains no special nuclear material and emits little .alpha.-particle radiation. The weapons-grade plutonium radiation surrogate also emits neutrons having fluxes commensurate with the gamma-radiation intensities employed.

  7. Radiative Accelerations in Stellar Evolution

    E-print Network

    G. Michaud; J. Richer

    2008-01-26

    A brief review of various methods to calculate radiative accelerations for stellar evolution and an analysis of their limitations are followed by applications to Pop I and Pop II stars. Recent applications to Horizontal Branch (HB) star evolution are also described. It is shown that models including atomic diffusion satisfy Schwarzschild's criterion on the interior side of the core boundary on the HB without the introduction of overshooting. Using stellar evolution models starting on the Main Sequence and calculated throughout evolution with atomic diffusion, radiative accelerations are shown to lead to abundance anomalies similar to those observed on the HB of M15.

  8. Research Update: Reactively sputtered nanometer-thin ZrN film as a diffusion barrier between Al and boron layers for radiation detector applications

    SciTech Connect

    Golshani, Negin Mohammadi, V.; Schellevis, H.; Beenakker, C. I. M.; Ishihara, R.

    2014-10-01

    In this paper, optimization of the process flow for PureB detectors is investigated. Diffusion barrier layers between a boron layer and the aluminum interconnect can be used to enhance the performance and visual appearance of radiation detectors. Few nanometers-thin Zirconium Nitride (ZrN) layer deposited by reactive sputtering in a mixture of Ar/N{sub 2}, is identified as a reliable diffusion barrier with better fabrication process compatibility than others. The barrier properties of this layer have been tested for different boron layers deposited at low and high temperatures with extensive optical microscopy analyses, electron beam induced current, SEM, and electrical measurements. This study demonstrated that spiking behavior of pure Al on Si can be prevented by the thin ZrN layer thus improving the performance of the radiation detectors fabricated using boron layer.

  9. Research Update: Reactively sputtered nanometer-thin ZrN film as a diffusion barrier between Al and boron layers for radiation detector applications

    NASA Astrophysics Data System (ADS)

    Golshani, Negin; Mohammadi, V.; Schellevis, H.; Beenakker, C. I. M.; Ishihara, R.

    2014-10-01

    In this paper, optimization of the process flow for PureB detectors is investigated. Diffusion barrier layers between a boron layer and the aluminum interconnect can be used to enhance the performance and visual appearance of radiation detectors. Few nanometers-thin Zirconium Nitride (ZrN) layer deposited by reactive sputtering in a mixture of Ar/N2, is identified as a reliable diffusion barrier with better fabrication process compatibility than others. The barrier properties of this layer have been tested for different boron layers deposited at low and high temperatures with extensive optical microscopy analyses, electron beam induced current, SEM, and electrical measurements. This study demonstrated that spiking behavior of pure Al on Si can be prevented by the thin ZrN layer thus improving the performance of the radiation detectors fabricated using boron layer.

  10. Radiation effects in space

    SciTech Connect

    Fry, R.J.M.

    1986-01-01

    The paper discusses the radiation environment in space that astronauts are likely to be exposed to. Emphasis is on proton and HZE particle effects. Recommendations for radiation protection guidelines are presented. (ACR)

  11. Space Radiation Program Element

    NASA Technical Reports Server (NTRS)

    Krenek, Sam

    2008-01-01

    This poster presentation shows the various elements of the Space Radiation Program. It reviews the program requirements: develop and validate standards, quantify space radiation human health risks, mitigate risks through countermeasures and technologies, and treat and monitor unmitigated risks.

  12. Environmental Radiation Exposures

    Cancer.gov

    DCEG is investigating cancer risks among populations exposed to radiation from environmental sources, such as nuclear reactor accidents and fallout from weapons testing.   Atomic Bomb Survivors Childhood Leukemia and Background Radiation Semipalatinsk

  13. Radiation Exposure and Cancer

    MedlinePLUS

    ... what we know about these types of high-energy radiation and how they affect cancer risk. Cancer Compensation Programs for People Exposed to Radiation as Part of Nuclear Weapons Testing Between 1945 and 1962, several countries ...

  14. Radiation Protection Handbook

    NASA Technical Reports Server (NTRS)

    1972-01-01

    A handbook which sets forth the Kennedy Space Center radiation protection policy is presented. The book also covers administrative direction and guidance on organizational and procedural requirements of the program. Only ionizing radiation is covered.

  15. Fluorescent radiation converter

    NASA Technical Reports Server (NTRS)

    Viehmann, W. (inventor)

    1981-01-01

    A fluorescence radiation converter is described which includes a substantially undoped optically transparent substrate and a waveshifter coating deposited on at least one portion of the substrate for absorption of radiation and conversion of fluorescent radiation. The coating is formed to substantially 1000 g/liter of a solvent, 70 to 200 g/liter of an organic polymer, and 0.2 to 25 g/liter of at least one organic fluorescent dye. The incoming incident radiation impinges on the coating. Radiation is absorbed by the fluorescent dye and is re-emitted as a longer wavelength radiation. Radiation is trapped within the substrate and is totally internally reflected by the boundary surface. Emitted radiation leaves the substrate ends to be detected.

  16. Cell Radiation Experiment System

    NASA Technical Reports Server (NTRS)

    Morrison, Dennis R.

    2010-01-01

    The cell radiation experiment system (CRES) is a perfused-cell culture apparatus, within which cells from humans or other animals can (1) be maintained in homeostasis while (2) being exposed to ionizing radiation during controlled intervals and (3) being monitored to determine the effects of radiation and the repair of radiation damage. The CRES can be used, for example, to determine effects of drug, radiation, and combined drug and radiation treatments on both normal and tumor cells. The CRES can also be used to analyze the effects of radiosensitive or radioprotectant drugs on cells subjected to radiation. The knowledge gained by use of the CRES is expected to contribute to the development of better cancer treatments and of better protection for astronauts, medical-equipment operators, and nuclear-power-plant workers, and others exposed frequently to ionizing radiation.

  17. Prostate Cancer (Radiation Therapy)

    MedlinePLUS

    ... control the cancer. If I choose surgery, will radiation treatment still be required? If your surgery is ... option with your physician team. If I choose radiation therapy, will surgical treatment still be an option? ...

  18. Pregnancy and Radiation Exposure

    MedlinePLUS

    ... Renew Ask the Experts Members Only Pregnancy and Radiation Exposure Robert Brent, MD, PhD The following information pertains to reproductive risks of radiation exposures to women who are pregnant and have ...

  19. Relation of the energy and pitch-angle diffusion of charged particles to the emitted radiation in small-scale astrophysical turbulence

    NASA Astrophysics Data System (ADS)

    Keenan, Brett; Ford, Alex; Medvedev, Mikhail

    2015-04-01

    Plasma turbulence in some energetic astrophysical objects, such as weakly magnetized collisionless shocks in GRBs and SN, has intense fluctuations at very small small scales. We investigate the relation of the characteristics of radiation produced by charged particles (relativistic through non-relativistic) moving in such turbulence and relate it to the diffusion of these particles in the velocity/energy space. We demonstrate that in contrast to the case of homogeneous B-field, radiation in the sub-Larmor-scale and rapidly fluctuating turbulence reflects statistical and temporal properties of the underlying electromagnetic fields. Both analytical estimates and the results of ab initio numerical simulations will be presented. We also confirm that particle propagation in such turbulence is diffusive. We evaluate the diffusion coefficients in the velocity space and demonstrate strong coupling of transport and radiation properties, which can be very valuable for remote diagnostics of astrophysical plasmas. Supported by DOE Grant DE-FG02-07ER54940 and NSF Grant AST-1209665.

  20. An evaluation of the contribution of radiation diffusion to thermal conductivity in high-pressure discharge lamps from operating-voltage and wall-temperature measurements

    NASA Astrophysics Data System (ADS)

    Born, M.

    1999-04-01

    The contribution of the radiation diffusion 0022-3727/32/8/007/img1 to the thermal conductivity 0022-3727/32/8/007/img2 in high-pressure discharge lamps is evaluated from operating-voltage and wall-temperature measurements for several cylindrical ceramic discharge tubes filled with mercury and argon as the rare gas. From calculations of 0022-3727/32/8/007/img1 using spectral line data of mercury, it is shown that the electrical conductivity 0022-3727/32/8/007/img4 can be well represented by a linear function of the heat-flux potential S. Under this assumption, the energy balance can be solved analytically and plasma parameters, i.e. radiation-diffusion and plasma-temperature profiles, can be calculated from the operating voltage and wall temperature without knowledge of spectral lines. The results are in good agreement with numerical calculations of the energy balance involving calculation of the radiation diffusion from spectral line data. The method may also be applied to other buffer gases for which there is a linear dependency of 0022-3727/32/8/007/img5. This may be checked qualitatively by measurement of the temporal evolution of the operating voltage using the Cassie-Francis equation.

  1. Radiation port dermatophytosis

    SciTech Connect

    Rosen, T.; Dupuy, J.; Maor, M.; Altman, A.

    1988-12-01

    We report two cases in which dermatophytic infection developed almost entirely within a radiation field mimicking an acute radiation effect. Radiotherapists and dermatologists should be aware of this possibility and be able to differentiate it from radiation dermatitis. Topical antifungal agents are the recommended treatment after diagnosis is established.

  2. astroph/9507030 Gravitational Radiation

    E-print Network

    Fygenson, Deborah Kuchnir

    astro­ph/9507030 10 Jul 95 Gravitational Radiation and Very Long Baseline Interferometry Ted Pyne of gravitational radiation on astrometric observations. We derive an equation for the time delay measured by two antennae observing the same source in an Einstein­de Sitter spacetime containing gravitational radiation

  3. Radiation Damping with Inhomogeneous

    E-print Network

    Augustine, Mathew P.

    Radiation Damping with Inhomogeneous Broadening: Limitations of the Single Bloch Vector Model of inhomoge- neous broadening on radiation damping of free precession signals have been described using 13: 1 7, 2001 KEY WORDS: radiation damping; FID shape; inhomogeneous broadening The phenomenon

  4. Radiation Research Program (RRP)

    Cancer.gov

    The RRP is responsible for NCI’s clinically-related extramural radiation research program. The RRP establishes priorities, allocates resources, and evaluates the effectiveness of such radiation research being conducted by NCI grantees. RRP staff represent the program at NCI management and scientific meetings and provide scientific support to leadership on matters related to radiation research.

  5. Radiation and cellular response

    SciTech Connect

    Scott, G.P.; Wahner, H.W.

    1983-01-01

    This book contains 18 papers. Some of the titles are: Radiation Equivalency for the Radiation Recall Phenomenon; The Induction of Photoreactivatable Damage in E. Coli by Ionizing Radiation: The Role of Cerenkov; Combined Modality Therapy for Limited Inoperable Non-Small Lung Cancer; and Learning and the Single Cell.

  6. Preservation of the optic radiations based on comparative analysis of diffusion tensor imaging tractography and anatomical dissection

    PubMed Central

    Nooij, Roland P.; Hoving, Eelco W.; van Hulzen, Arjen L. J.; Cornelissen, Frans W.; Renken, Remco J.

    2015-01-01

    Background: Visualization of the precise course of the visual pathways is relevant to prevent damage that may inflict visual field deficits during neurosurgical resections. In particular the optic radiations (OR) are susceptible to such damage during neurosurgery. Cortical pathways can be mapped in vivo, by using Diffusion Tensor Imaging (DTI). Visualization of these pathways would be potentially helpful to prevent neurosurgical visual morbidity. In this study an anatomical dissection of the visual pathways was compared to DTI fiber tractography (DTI-FT) data of four human brains. The feasibility of a definition of a Safety Zone is investigated. Methods: Four adult brains were dissected using Klingler's fiber dissection method, which allowed preparation of the OR. Measurements before and after dissection were used to establish distances from the cortex to the OR. DTI-scans were also obtained from these brains to determine the same distances. Results: Measurements from specific landmark points on the cortex to the lateral border of the OR were performed in four brains. Analysis through DTI tractography corresponded with the dissection results. Based on the combined results of both dissection and DTI-FT, we defined a quantitative surgical Safety Zone with respect to various anatomical landmarks (in particular the ventricle system). Conclusion: We conclude that there is a good correlation between the visualizations of the optic pathways based on dissection and DTI. Furthermore, we conclude that defining a neurosurgical Safety Zone which could preserve the integrity of the OR during surgery, based on the combination of DTI-FT images and dissection is feasible. PMID:26300739

  7. Radiation Therapy: Additional Treatment Options

    MedlinePLUS

    ... Upper GI What is Radiation Therapy? Find a Radiation Oncologist Last Name: Facility: City: State: Zip Code: ... infections. This is refered to as immunotherapy . Intraoperative Radiation Therapy Radiation therapy given during surgery is called ...

  8. Doses from Medical Radiation Sources

    MedlinePLUS

    ... Ask the Experts Members Only Doses from Medical Radiation Sources Michael G. Stabin, PhD, CHP Introduction Radiation ... interruption of feeding may be necessary. Doses in Radiation Therapy In radiation therapy, much higher doses are ...

  9. Radiation Injury to the Brain

    MedlinePLUS

    ... search IRSA's site Unique Hits since January 2003 RADIATION INJURY TO THE BRAIN Radiation treatments affect all ... accurate treatment is still with one session radiosurgery. RADIATION THERAPY: Whole brain radiation therapy (WBRT) may target ...

  10. Radiation protection in space

    SciTech Connect

    Blakely, E.A.; Fry, R.J.M.

    1995-02-01

    The challenge for planning radiation protection in space is to estimate the risk of events of low probability after low levels of irradiation. This work has revealed many gaps in the present state of knowledge that require further study. Despite investigations of several irradiated populations, the atomic-bomb survivors remain the primary basis for estimating the risk of ionizing radiation. Compared to previous estimates, two new independent evaluations of available information indicate a significantly greater risk of stochastic effects of radiation (cancer and genetic effects) by about a factor of three for radiation workers. This paper presents a brief historical perspective of the international effort to assure radiation protection in space.

  11. Solar cell radiation handbook

    NASA Technical Reports Server (NTRS)

    Carter, J. R., Jr.; Tada, H. Y.

    1973-01-01

    A method is presented for predicting the degradation of a solar array in a space radiation environment. Solar cell technology which emphasizes the cell parameters that degrade in a radiation environment, is discussed along with the experimental techniques used in the evaluation of radiation effects. Other topics discussed include: theoretical aspects of radiation damage, methods for developing relative damage coefficients, nature of the space radiation environment, method of calculating equivalent fluence from electron and proton energy spectrums and relative damage coefficients, and comparison of flight data with estimated degradation.

  12. Radiation protection and instrumentation

    NASA Technical Reports Server (NTRS)

    Bailey, J. V.

    1975-01-01

    Radiation was found not to be an operational problem during the Apollo program. Doses received by the crewmen of Apollo missions 7 through 17 were small because no major solar-particle events occurred during those missions. One small event was detected by a radiation sensor outside the Apollo 12 spacecraft, but no increase in radiation dose to the crewmen inside the spacecraft was detected. Radiation protection for the Apollo program was focused on both the peculiarities of the natural space radiation environment and the increased prevalence of manmade radiation sources on the ground and onboard the spacecraft. Radiation-exposure risks to crewmen were assessed and balanced against mission gain to determine mission constraints. Operational radiation evaluation required specially designed radiation detection systems onboard the spacecraft in addition to the use of satellite data, solar observatory support, and other liaison. Control and management of radioactive sources and radiation-generating equipment was important in minimizing radiation exposure of ground-support personnel, researchers, and the Apollo flight and backup crewmen.

  13. Radiation-induced gliomas

    PubMed Central

    Prasad, Gautam; Haas-Kogan, Daphne A.

    2013-01-01

    Radiation-induced gliomas represent a relatively rare but well-characterized entity in the neuro-oncologic literature. Extensive retrospective cohort data in pediatric populations after therapeutic intracranial radiation show a clearly increased risk in glioma incidence that is both patient age- and radiation dose/volume-dependent. Data in adults are more limited but show heightened risk in certain groups exposed to radiation. In both populations, there is no evidence linking increased risk associated with routine exposure to diagnostic radiation. At the molecular level, recent studies have found distinct genetic differences between radiation-induced gliomas and their spontaneously-occurring counterparts. Clinically, there is understandable reluctance on the part of clinicians to re-treat patients due to concern for cumulative neurotoxicity. However, available data suggest that aggressive intervention can lead to improved outcomes in patients with radiation-induced gliomas. PMID:19831840

  14. Americans' Average Radiation Exposure

    SciTech Connect

    NA

    2000-08-11

    We live with radiation every day. We receive radiation exposures from cosmic rays, from outer space, from radon gas, and from other naturally radioactive elements in the earth. This is called natural background radiation. It includes the radiation we get from plants, animals, and from our own bodies. We also are exposed to man-made sources of radiation, including medical and dental treatments, television sets and emission from coal-fired power plants. Generally, radiation exposures from man-made sources are only a fraction of those received from natural sources. One exception is high exposures used by doctors to treat cancer patients. Each year in the United States, the average dose to people from natural and man-made radiation sources is about 360 millirem. A millirem is an extremely tiny amount of energy absorbed by tissues in the body.

  15. Gas particle radiator

    NASA Technical Reports Server (NTRS)

    Chubb, Donald L.

    1987-01-01

    The performance of a new space radiator concept, the gas particle radiator (GPR), is studied. The GPR uses a gas containing submicron particles as the radiating medium contained between the radiator's emitting surface and a transparent window. For a modest volume fraction of submicron particles and gas thickness, it is found that the emissivity is determined by the window transmittance. The window must have a high transmittance in the infrared and be structurally strong enough to contain the gas-particle mixture. When the GPR is compared to a proposed titanium wall, potassium heat pipe radiator, with both radiators operating at a power level of 1.01 MW at 775 K, it is found that the GPR mass is 31 percent lower than that of the heat pipe radiator.

  16. Radiation curing of epoxies

    NASA Astrophysics Data System (ADS)

    Dickson, Lawrence W.; Singh, Ajit

    The literature on radiation polymerization of epoxy compounds has been reviewed to assess the potential use of radiation for curing these industrially important monomers. Chemical curing of epoxies may proceed by either cationic or anionic mechanisms depending on the nature of the curing agent, but most epoxies polymerize by cationic mechanisms under the influence of high-energy radiation. Radiation-induced cationic polymerization of epoxy compounds is inhibited by trace quantities of water because of proton transfer from the chain-propagating epoxy cation to water. Several different methods with potential for obtaining high molecular weight polymers by curing epoxies with high-energy radiation have been studied. Polymeric products with epoxy-like properties have been produced by radiation curing of epoxy oligomers with terminal acrylate groups and mixtures of epoxies with vinyl monomers. Both of these types of resin have good potential for industrial-scale curing by radiation treatment.

  17. RF radiation from lightning

    NASA Technical Reports Server (NTRS)

    Levine, D. M.

    1978-01-01

    Radiation from lightning in the RF band from 3-300 MHz were monitored. Radiation in this frequency range is of interest as a potential vehicle for monitoring severe storms and for studying the lightning itself. Simultaneous measurements were made of RF radiation and fast and slow field changes. Continuous analogue recordings with a system having 300 kHz of bandwidth were made together with digital records of selected events (principally return strokes) at greater temporal resolution. The data reveal patterns in the RF radiation for the entire flash which are characteristic of flash type and independent of the frequency of observation. Individual events within the flash also have characteristic RF patterns. Strong radiation occurs during the first return strokes, but delayed about 20 micron sec with respect to the begining of the return stroke; whereas, RF radiation from subsequent return strokes tends to be associated with cloud processes preceding the flash with comparatively little radiation occurring during the return stroke itself.

  18. Local Versus Long-Range Diffusion Effects of Photoexcited States on Radiative Recombination in Organic–Inorganic Lead Halide Perovskites

    E-print Network

    Vru?ini?, Milan; Matthiesen, Clemens; Sadhanala, Aditya; Divitini, Giorgio; Cacovich, Stefania; Dutton, Sian E.; Ducati, Caterina; Atatüre, Mete; Snaith, Henry; Friend, Richard H.; Sirringhaus, Henning; Deschler, Felix

    2015-07-14

    Radiative recombination in thin films of the archetypical, high-performing perovskites CH?NH?PbBr? and CH?NH?PbI? shows localized regions of increased emission with dimensions ? 500 nm. Maps of the spectral emission line shape show narrower emission...

  19. Complications of radiation therapy

    SciTech Connect

    Dalinka, M.K.; Mazzeo, V.P. Jr.

    1985-01-01

    The skeletal effects of radiation are dependent upon many variables, but the pathologic features are consistent. Radiation may cause immediate or delayed cell death, cellular injury with recovery, arrest of cellular division, or abnormal repair with neoplasia. Radiation necrosis and radiation-induced neoplasm still occur despite the use of supervoltage therapy. Complications of radiotherapy are well known and have led to more judicious use of this therapeutic modality. With few exceptions, benign bone tumors are no longer treated with irradiation. Radiation necrosis may be difficult to differentiate from sarcoma arising in irradiated bone. They both occur within the field of irradiation. Radiation necrosis often has a long latent period which is, of course, the rule in radiation-induced neoplasia. A soft tissue mass favors the diagnosis of neoplasia, while its absence suggests radiation necrosis. Lack of pain favors necrosis. Calcification may occur in radiation necrosis and does not indicate neoplasia. A lack of progression on serial roentgenograms also favors radiation necrosis. 76 references.

  20. Radiation physics, biophysics, and radiation biology

    SciTech Connect

    Hall, E.J.; Zaider, M.

    1993-05-01

    Research at the Center for Radiological Research is a multidisciplenary blend of physics, chemistry and biology aimed at understanding the mechanisms involved in the health problems resulting from human exposure to ionizing radiations. The focus is increased on biochemistry and the application of the techniques of molecular biology to the problems of radiation biology. Research highlights of the program from the past year are described. A mathematical model describing the production of single-strand and double-strand breaks in DNA as a function radiation quality has been completed. For the first time Monte Carlo techniques have been used to obtain directly the spatial distribution of DNA moieties altered by radiation. This information was obtained by including the transport codes a realistic description of the electronic structure of DNA. We have investigated structure activity relationships for the potential oncogenicity of a new generation of bioreductive drugs that function as hypoxic cytotoxins. Experimental and theoretical investigation of the inverse dose rate effect, whereby medium LET radiations actually produce an c effect when the dose is protracted, is now at a point where the basic mechanisms are reasonably understood and the complex interplay between dose, dose rate and radiation quality which is necessary for the effect to be present can now be predicted at least in vitro. In terms of early radiobiological damage, a quantitative link has been established between basic energy deposition and locally multiply damaged sites, the radiochemical precursor of DNA double strand breaks; specifically, the spatial and energy deposition requirements necessary to form LMDs have been evaluated. For the first time, a mechanically understood biological fingerprint'' of high-LET radiation has been established. Specifically measurement of the ratio of inter-to intra-chromosomal aberrations produces a unique signature from alpha-particles or neutrons.

  1. Velocity diffusion and radiation trapping force in a one-dimensional expansion of cold atomic clouds in a magneto-optical trap

    SciTech Connect

    Pradhan, S.; Mayya, Y. S.; Jagatap, B. N.

    2007-09-15

    We experimentally investigate one-dimensional (1D) expansion of a cold cloud of cesium atoms in orthogonal 2D configuration of near resonant laser beams by temporally modulating a pair of counterpropagating trapping beams of a magneto-optical trap (MOT). The cloud is observed to undergo ballistic expansion followed by superballistic explosive growth due to the fluctuations of the 2D radiation force. A model based on the theory of Brownian motion is developed and a comparison of experiments with theory is shown to provide a direct measure of the velocity diffusion coefficient. We also observe sudden contraction of the cloud immediately after switching off the pair of trapping beams, which provides direct evidence for the existence of the radiation trapping force in a MOT.

  2. Errors inducing radiation overdoses.

    PubMed

    Grammaticos, Philip C

    2013-01-01

    There is no doubt that equipments exposing radiation and used for therapeutic purposes should be often checked for possibly administering radiation overdoses to the patients. Technologists, radiation safety officers, radiologists, medical physicists, healthcare providers and administration should take proper care on this issue. "We must be beneficial and not harmful to the patients", according to the Hippocratic doctrine. Cases of radiation overdose are often reported. A series of cases of radiation overdoses have recently been reported. Doctors who were responsible, received heavy punishments. It is much better to prevent than to treat an error or a disease. A Personal Smart Card or Score Card has been suggested for every patient undergoing therapeutic and/or diagnostic procedures by the use of radiation. Taxonomy may also help. PMID:24251304

  3. The flying radiation case

    SciTech Connect

    Brownell, J.H.; Bowers, R.L.

    1997-04-01

    The Los Alamos foil implosion program has the goal of producing an intense, high-energy density x-ray source by converting the energy of a magnetically imploded plasma into radiation and material energy. One of the methods for converting the plasma energy into thermal energy and radiation and utilizing it for experiments is called the flying radiation case (FRC). In this paper the authors shall model the FRC and provide a physical description of the processes involved. An analytic model of a planar FRC in the hydrodynamic approximation is used to describe the assembly and shock heating of a central cushion by a conducting liner driver. The results are also used to benchmark a hydrodynamics code for modeling an FRC. They then use a radiation-hydrodynamics computational model to explore the effects of radiation production and transport when a gold plasma assembles on a CH cushion. Results are presented for the structure and evolution of the radiation hohlraum.

  4. Earth Radiation Measurement Science

    NASA Technical Reports Server (NTRS)

    Smith, G. Louis

    2000-01-01

    This document is the final report for NASA Grant NAG1-1959, 'Earth Radiation Measurement Science'. The purpose of this grant was to perform research in this area for the needs of the Clouds and Earth Radiant Energy System (CERES) project and for the Earth Radiation Budget Experiment (ERBE), which are bing conducted by the Radiation and Aerosols Branch of the Atmospheric Sciences Division of Langley Research Center. Earth Radiation Measurement Science investigates the processes by which measurements are converted into data products. Under this grant, research was to be conducted for five tasks: (1) Point Response Function Measurements; (2) Temporal Sampling of Outgoing Longwave Radiation; (3) Spatial Averaging of Radiation Budget Data; (4) CERES Data Validation and Applications; and (5) ScaRaB Data Validation and Application.

  5. RHOBOT: Radiation hardened robotics

    SciTech Connect

    Bennett, P.C.; Posey, L.D.

    1997-10-01

    A survey of robotic applications in radioactive environments has been conducted, and analysis of robotic system components and their response to the varying types and strengths of radiation has been completed. Two specific robotic systems for accident recovery and nuclear fuel movement have been analyzed in detail for radiation hardness. Finally, a general design approach for radiation-hardened robotics systems has been developed and is presented. This report completes this project which was funded under the Laboratory Directed Research and Development program.

  6. Flexible radiator system

    NASA Technical Reports Server (NTRS)

    Oren, J. A.

    1982-01-01

    The soft tube radiator subsystem is described including applicable system requirements, the design and limitations of the subsystem components, and the panel manufacturing method. The soft tube radiator subsystem is applicable to payloads requiring 1 to 12 kW of heat rejection for orbital lifetimes per mission of 30 days or less. The flexible radiator stowage volume required is about 60% and the system weight is about 40% of an equivalent heat rejection rigid panel. The cost should also be considerably less. The flexible radiator is particularly suited to shuttle orbiter sortie payloads and also whose mission lengths do not exceed the 30 day design life.

  7. Charms of radiation research.

    SciTech Connect

    Inokuti, M.; Physics

    2005-01-01

    Most of my professional efforts over nearly five decades have been devoted to radiation research, that is, studies of the physical, chemical, and biological actions of high-energy radiation on matter. (By the term 'high-energy radiation' I mean here x rays, .GAMMA. rays, neutrons, and charged particles of high enough energies to produce ionization in matter. I exclude visible light, infrared waves, microwaves, and sound waves.) Charms of radiation research lie in its interdisciplinary character; although my training was in basic physics, the scope of my interest has gradually increased to cover many other areas, to my deep satisfaction. High-energy radiation is an important component of the universe, and of our environment. It often provides an effective avenue for characterizing matter and understanding its behavior. Near Earth's surface this radiation is normally present in exceptionally low quantity, and yet it plays a significant role in some atmospheric phenomena such as auroras, and also in the evolution of life. The recent advent of various devices for producing high-energy radiation has opened up the possibility of many applications, including medical and industrial uses. I have worked on some aspects of those uses. At every opportunity to address a broad audience I try to convey a sense of intellectual fun, together with some of the elements of the basic science involved. A goal of radiation education might be to make the word 'radiation' as common and familiar as words such as 'fire' and 'electricity' through increased usage.

  8. Radiation coloration resistant glass

    DOEpatents

    Tomozawa, M.; Watson, E.B.; Acocella, J.

    1986-11-04

    A radiation coloration resistant glass is disclosed which is used in a radiation environment sufficient to cause coloration in most forms of glass. The coloration resistant glass includes higher proportions by weight of water and has been found to be extremely resistant to color change when exposed to such radiation levels. The coloration resistant glass is free of cerium oxide and has more than about 0.5% by weight water content. Even when exposed to gamma radiation of more than 10[sup 7] rad, the coloration resistant glass does not lose transparency. 3 figs.

  9. Radiation coloration resistant glass

    DOEpatents

    Tomozawa, Minoru (Troy, NY); Watson, E. Bruce (Troy, NY); Acocella, John (Troy, NY)

    1986-01-01

    A radiation coloration resistant glass is disclosed which is used in a radiation environment sufficient to cause coloration in most forms of glass. The coloration resistant glass includes higher proportions by weight of water and has been found to be extremely resistant to color change when exposed to such radiation levels. The coloration resistant glass is free of cerium oxide and has more than about 0.5% by weight water content. Even when exposed to gamma radiation of more than 10.sup.7 rad, the coloration resistant glass does not lose transparency.

  10. Potential theory of radiation

    NASA Technical Reports Server (NTRS)

    Chiu, Huei-Huang

    1989-01-01

    A theoretical method is being developed by which the structure of a radiation field can be predicted by a radiation potential theory, similar to a classical potential theory. The introduction of a scalar potential is justified on the grounds that the spectral intensity vector is irrotational. The vector is also solenoidal in the limits of a radiation field in complete radiative equilibrium or in a vacuum. This method provides an exact, elliptic type equation that will upgrade the accuracy and the efficiency of the current CFD programs required for the prediction of radiation and flow fields. A number of interesting results emerge from the present study. First, a steady state radiation field exhibits an optically modulated inverse square law distribution character. Secondly, the unsteady radiation field is structured with two conjugate scalar potentials. Each is governed by a Klein-Gordon equation with a frictional force and a restoring force. This steady potential field structure and the propagation of radiation potentials are consistent with the well known results of classical electromagnetic theory. The extension of the radiation potential theory for spray combustion and hypersonic flow is also recommended.

  11. Atomistic modeling of intrinsic and radiation-enhanced fission gas (Xe) diffusion in UO2±x: Implications for nuclear fuel performance modeling

    NASA Astrophysics Data System (ADS)

    Andersson, D. A.; Garcia, P.; Liu, X.-Y.; Pastore, G.; Tonks, M.; Millett, P.; Dorado, B.; Gaston, D. R.; Andrs, D.; Williamson, R. L.; Martineau, R. C.; Uberuaga, B. P.; Stanek, C. R.

    2014-08-01

    Based on density functional theory (DFT) and empirical potential calculations, the diffusivity of fission gas atoms (Xe) in UO2 nuclear fuel has been calculated for a range of non-stoichiometry (i.e. UO2±x), under both out-of-pile (no irradiation) and in-pile (irradiation) conditions. This was achieved by first deriving expressions for the activation energy that account for the type of trap site that the fission gas atoms occupy, which includes the corresponding type of mobile cluster, the charge state of these defects and the chemistry acting as boundary condition. In the next step DFT calculations were used to estimate migration barriers and internal energy contributions to the thermodynamic properties and calculations based on empirical potentials were used to estimate defect formation and migration entropies (i.e. pre-exponentials). The diffusivities calculated for out-of-pile conditions as function of the UO2±x non-stoichiometry were used to validate the accuracy of the diffusion models and the DFT calculations against available experimental data. The Xe diffusivity is predicted to depend strongly on the UO2±x non-stoichiometry due to a combination of changes in the preferred Xe trap site and in the concentration of uranium vacancies enabling Xe diffusion, which is consistent with experiments. After establishing the validity of the modeling approach, it was used for studying Xe diffusion under in-pile conditions, for which experimental data is very scarce. The radiation-enhanced Xe diffusivity is compared to existing empirical models. Finally, the predicted fission gas diffusion rates were implemented in the BISON fuel performance code and fission gas release from a Risø fuel rod irradiation experiment was simulated.

  12. Atomistic modeling of intrinsic and radiation-enhanced fission gas (Xe) diffusion in UO2 +/- x: Implications for nuclear fuel performance modeling

    SciTech Connect

    Giovanni Pastore; Michael R. Tonks; Derek R. Gaston; Richard L. Williamson; David Andrs; Richard Martineau

    2014-03-01

    Based on density functional theory (DFT) and empirical potential calculations, the diffusivity of fission gas atoms (Xe) in UO2 nuclear fuel has been calculated for a range of non-stoichiometry (i.e. UO2x), under both out-of-pile (no irradiation) and in-pile (irradiation) conditions. This was achieved by first deriving expressions for the activation energy that account for the type of trap site that the fission gas atoms occupy, which includes the corresponding type of mobile cluster, the charge state of these defects and the chemistry acting as boundary condition. In the next step DFT calculations were used to estimate migration barriers and internal energy contributions to the thermodynamic properties and calculations based on empirical potentials were used to estimate defect formation and migration entropies (i.e. pre-exponentials). The diffusivities calculated for out-of-pile conditions as function of the UO2x nonstoichiometrywere used to validate the accuracy of the diffusion models and the DFT calculations against available experimental data. The Xe diffusivity is predicted to depend strongly on the UO2x non-stoichiometry due to a combination of changes in the preferred Xe trap site and in the concentration of uranium vacancies enabling Xe diffusion, which is consistent with experiments. After establishing the validity of the modeling approach, it was used for studying Xe diffusion under in-pile conditions, for which experimental data is very scarce. The radiation-enhanced Xe diffusivity is compared to existing empirical models. Finally, the predicted fission gas diffusion rates were implemented in the BISON fuel performance code and fission gas release from a Risø fuel rod irradiation experiment was simulated. 2014 Elsevier B.V. All rights

  13. Radiation physics, biophysics, and radiation biology

    SciTech Connect

    Hall, E.J.

    1992-05-01

    The following research programs from the Center for Radiological Research of Columbia University are described: Design and development of a new wall-less ultra miniature proportional counter for nanodosimetry; some recent measurements of ionization distributions for heavy ions at nanometer site sizes with a wall-less proportional counter; a calculation of exciton energies in periodic systems with helical symmetry: application to a hydrogen fluoride chain; electron energy-loss function in polynucleotide and the question of plasmon excitation; a non-parametric, microdosimetric-based approach to the evaluation of the biological effects of low doses of ionizing radiation; high-LET radiation risk assessment at medium doses; high-LET radiobiological effects: increased lesion severity or increased lesion proximity; photoneutrons generated by high energy medical linacs; the biological effectiveness of neutrons; implications for radiation protection; molecular characterization of oncogenes induced by neutrons; and the inverse dose-rate effect for oncogenic transformation by charged particles is LET dependent.

  14. Radiation pressure driving of a dusty atmosphere

    E-print Network

    Tsang, Benny Tsz-Ho

    2015-01-01

    Radiation pressure can be dynamically important in certain star-forming environments such as ultra-luminous infrared and submillimeter galaxies. Whether and how radiation drives turbulence and bulk outflows in star formation sites is still unclear. The uncertainty stems from the limitations of direct numerical schemes used to simulate radiation transfer and radiation-gas coupling. The idealized setup in which radiation is introduced at the base of a dusty atmosphere in a gravitational field has recently become a standard for the testing of radiation hydrodynamics methods in the context of star formation. To a series of treatments enlisting the flux-limited-diffusion approximation as well as a short-characteristics tracing and M1 closure for the variable Eddington tensor approximation, we here add another, very different treatment based on the Implicit Monte Carlo radiation transfer scheme. Consistent with all previous treatment, we observe Rayleigh-Taylor instability and a readjustment to a near-Eddington sta...

  15. Multiplate Radiation Shields: Investigating Radiational Heating Errors

    NASA Astrophysics Data System (ADS)

    Richardson, Scott James

    1995-01-01

    Multiplate radiation shield errors are examined using the following techniques: (1) analytic heat transfer analysis, (2) optical ray tracing, (3) numerical fluid flow modeling, (4) laboratory testing, (5) wind tunnel testing, and (6) field testing. Guidelines for reducing radiational heating errors are given that are based on knowledge of the temperature sensor to be used, with the shield being chosen to match the sensor design. Small, reflective sensors that are exposed directly to the air stream (not inside a filter as is the case for many temperature and relative humidity probes) should be housed in a shield that provides ample mechanical and rain protection while impeding the air flow as little as possible; protection from radiation sources is of secondary importance. If a sensor does not meet the above criteria (i.e., is large or absorbing), then a standard Gill shield performs reasonably well. A new class of shields, called part-time aspirated multiplate radiation shields, are introduced. This type of shield consists of a multiplate design usually operated in a passive manner but equipped with a fan-forced aspiration capability to be used when necessary (e.g., low wind speed). The fans used here are 12 V DC that can be operated with a small dedicated solar panel. This feature allows the fan to operate when global solar radiation is high, which is when the largest radiational heating errors usually occur. A prototype shield was constructed and field tested and an example is given in which radiational heating errors were reduced from 2 ^circC to 1.2 ^circC. The fan was run continuously to investigate night-time low wind speed errors and the prototype shield reduced errors from 1.6 ^ circC to 0.3 ^circC. Part-time aspirated shields are an inexpensive alternative to fully aspirated shields and represent a good compromise between cost, power consumption, reliability (because they should be no worse than a standard multiplate shield if the fan fails), and accuracy. In addition, it is possible to modify existing passive shields to incorporate part-time aspiration, thus making them even more cost-effective. Finally, a new shield is described that incorporates a large diameter top plate that is designed to shade the lower portion of the shield. This shield increases flow through it by 60%, compared to the Gill design and it is likely to reduce radiational heating errors, although it has not been tested.

  16. Ultraviolet-radiation-curable paints

    SciTech Connect

    Grosset, A M; Su, W F.A.; Vanderglas, E

    1981-09-30

    In product finishing lines, ultraviolet radiation curing of paints on prefabricated structures could be more energy efficient than curing by natural gas fired ovens, and could eliminate solvent emission. Diffuse ultraviolet light can cure paints on three dimensional metal parts. In the uv curing process, the spectral output of radiation sources must complement the absorption spectra of pigments and photoactive agents. Photosensitive compounds, such as thioxanthones, can photoinitiate unsaturated resins, such as acrylated polyurethanes, by a free radical mechanism. Newly developed cationic photoinitiators, such as sulfonium or iodonium salts (the so-called onium salts) of complex metal halide anions, can be used in polymerization of epoxy paints by ultraviolet light radiation. One-coat enamels, topcoats, and primers have been developed which can be photoinitiated to produce hard, adherent films. This process has been tested in a laboratory scale unit by spray coating these materials on three-dimensional objects and passing them through a tunnel containing uv lamps.

  17. Radiation: Facts, Risks and Realities

    E-print Network

    8 Radiation in Industry and Commerce 9 Exposure to Ionizing Radiation 11 Regulating Radiation Use 12 in genes. While there are other, less energetic, types of non- ionizing radiation (including radio waves, microwaves--and visible light), this booklet is about ionizing radiation. In the late 1800s, Marie and Pierre

  18. Tal Carmon Radiation pressure induced

    E-print Network

    Tal Carmon Radiation pressure induced vibrations Tal Carmon RP induced vibrations RP induced #12;Tal Carmon Radiation pressure induced vibrations Tal Carmon RP induced vibrations · First proposed radiation pressure to be the reason. Who is interested in radiation pressure? #12;Tal Carmon Radiation

  19. RADIATION ONCOLOGY TARGET YOUR FUTURE

    E-print Network

    Tobar, Michael

    RADIATION ONCOLOGY TARGET YOUR FUTURE #12;A Career in Radiation Oncology YOUR CHOICE SAVE LIVES Take the first step towards a career in Radiation Oncology Visit www.acareerinradiationoncology.com.au 2 What is Radiation Oncology? Radiation Oncology is made up of three unique medical specialties

  20. Radiative Flux Analysis

    SciTech Connect

    Long, Chuck

    2008-05-14

    The Radiative Flux Analysis is a technique for using surface broadband radiation measurements for detecting periods of clear (i.e. cloudless) skies, and using the detected clear-sky data to fit functions which are then used to produce continuous clear-sky estimates. The clear-sky estimates and measurements are then used in various ways to infer cloud macrophysical properties.

  1. Synchrotron Radiation II.

    ERIC Educational Resources Information Center

    MOSAIC, 1978

    1978-01-01

    Synchrotron radiation is a unique form of radiation that spans the electro-magnetic spectrum from X-rays through the ultraviolet and visible into the infrared. Tunable monochromators enable scientists to select a narrow band of wavelengths at any point in the spectrum. (Author/BB)

  2. Treatment of Radiation Injury

    PubMed Central

    Akita, Sadanori

    2014-01-01

    Significance: Radiation exposure as a result of radiation treatment, accident, or terrorism may cause serious problems such as deficiency due to necrosis or loss of function, fibrosis, or intractable ulcers in the tissues and organs. When the skin, bone, oral mucous membrane, guts, or salivary glands are damaged by ionizing radiation, the management and treatment are very lengthy and difficult. Critical Issues: In severe and irreversible injuries, surgery remains the mainstay of treatment. Several surgical procedures, such as debridement, skin grafting, and local and free-vascularized flaps, are widely used. Recent Advances: In specific cases of major morbidity or in high-risk patients, a newly developed therapy using a patient's own stem cells is safe and effective. Adipose tissue, normally a rich source of mesenchymal stem cells, which are similar to those from the bone marrow, can be harvested, since the procedure is easy, and abundant tissue can be obtained with minimal invasiveness. Future Directions: Based on the molecular basis of radiation injuries, several prospective treatments are under development. Single-nucleotide polymorphisms focus on an individual's sensitivity to radiation in radiogenomics, and the pathology of radiation fibrosis or the effect of radiation on wound healing is being studied and will lead to new insight into the treatment of radiation injuries. Protectors and mitigators are being actively investigated in terms of the timing of administration or dose. PMID:24761339

  3. Radiation: Doses, Effects, Risks.

    ERIC Educational Resources Information Center

    Lean, Geoffrey, Ed.

    Few scientific issues arouse as much public controversy as the effects of radiation. This booklet is an attempt to summarize what is known about radiation and provide a basis for further discussion and debate. The first four chapters of the booklet are based on the most recent reports to the United Nations' General Assembly by the United Nations…

  4. Radiation in the universe

    NASA Technical Reports Server (NTRS)

    Stuhlinger, Ernst; Truemper, Joachim; Weisskopf, Martin

    1992-01-01

    When Wilhelm Conrad Roentgen discovered radiation one hundred years ago, it seemed that what was discovered was one of the rarest and most volatile members of the family of the basic modules of our natural world. Today cosmologists report that a substantial part of the universe's radiation energy consists of X-rays, which travel through cosmic space with the speed of light.

  5. Radiation-resistant microorganism

    DOEpatents

    Fliermans, Carl B.

    2010-06-15

    An isolated and purified bacterium is provided which was isolated from a high-level radioactive waste site of mixed waste. The isolate has the ability to degrade a wide variety of organic contaminants while demonstrating high tolerance to ionizing radiation. The organism is uniquely suited to bioremediation of a variety or organic contaminants while in the presence of ionizing radiation.

  6. Radiation-resistant microorganism

    DOEpatents

    Fliermans, Carl B.

    2007-01-09

    An isolated and purified bacterium is provided which was isolated from a high-level radioactive waste site of mixed waste. The isolate has the ability to degrade a wide variety of organic contaminants while demonstrating high tolerance to ionizing radiation. The organism is uniquely suited to bioremediation of a variety or organic contaminants while in the presence of ionizing radiation.

  7. Radiation effects in space

    SciTech Connect

    Fry, R.J.M.

    1987-07-01

    As more people spend more time in space, and the return to the moon and exploratory missions are considered, the risks require continuing examination. The effects of microgravity and radiation are two potential risks in space. These risks increase with increasing mission duration. This document considers the risk of radiation effects in space workers and explorers. 17 refs., 1 fig., 4 tabs.

  8. On Blackbody Radiation.

    ERIC Educational Resources Information Center

    Jain, Pushpendra K.

    1991-01-01

    The interrelationship between the various forms of the Planck radiation equation is discussed. A differential equation that gives intensity or energy density of radiation per unit wavelength or per unit frequency is emphasized. The Stefan-Boltzmann Law and the change in the glow of a hot body with temperature are also discussed. (KR)

  9. Ultraviolet radiation changes

    NASA Technical Reports Server (NTRS)

    Mckenzie, Richard L.; Frederick, John E.; Ilyas, Mohammad; Filyushkin, V.; Wahner, Andreas; Stamnes, K.; Muthusubramanian, P.; Blumthaler, M.; Roy, Colin E.; Madronich, Sasha

    1991-01-01

    A major consequence of ozone depletion is an increase in solar ultraviolet (UV) radiation received at the Earth's surface. This chapter discusses advances that were made since the previous assessment (World Meteorological Organization (WMO)) to our understanding of UV radiation. The impacts of these changes in UV on the biosphere are not included, because they are discussed in the effects assessment.

  10. Microcircuit radiation effects databank

    NASA Technical Reports Server (NTRS)

    1983-01-01

    Radiation test data submitted by many testers is collated to serve as a reference for engineers who are concerned with and have some knowledge of the effects of the natural radiation environment on microcircuits. Total dose damage information and single event upset cross sections, i.e., the probability of a soft error (bit flip) or of a hard error (latchup) are presented.

  11. Photochemistry Radiation and Photolysis

    E-print Network

    Toohey, Darin W.

    energy is done (i.e. energy per unit time) #12;Sample Problem: A microwave oven puts out radiation at 50? How does a microwave oven heat food anyway? First note that 50 GHz is a frequency (Hz = s-1) E = hn, as a function of l · Amount of solar radiation, as a function of

  12. Broadband optical radiation detector

    NASA Technical Reports Server (NTRS)

    Gupta, A.; Hong, S. D.; Moacanin, J. (inventors)

    1981-01-01

    A method and apparatus for detecting optical radiation by optically monitoring temperature changes in a microvolume caused by absorption of the optical radiation to be detected is described. More specifically, a thermal lens forming material is provided which has first and second opposite, substantially parallel surfaces. A reflective coating is formed on the first surface, and a radiation absorbing coating is formed on the reflective coating. Chopped, incoming optical radiation to be detected is directed to irradiate a small portion of the radiation absorbing coating. Heat generated in this small area is conducted to the lens forming material through the reflective coating, thereby raising the temperature of a small portion of the lens forming material and causing a thermal lens to be formed therein.

  13. Radiation Effects In Space

    SciTech Connect

    Tripathi, Ram K.

    2011-06-01

    Protecting space missions from severe exposures from radiation, in general, and long duration/deep space human missions, in particular, is a critical design driver, and could be a limiting factor. The space radiation environment consists of galactic cosmic rays (GCR), solar particle events (SPE), trapped radiation, and includes ions of all the known elements over a very broad energy range. These ions penetrate spacecraft materials producing nuclear fragments and secondary particles that damage biological tissues and microelectronic devices. One is required to know how every element (and all isotopes of each element) in the periodic table interacts and fragments on every other element in the same table as a function of kinetic energy ranging over many decades. In addition, the accuracy of the input information and database, in general and nuclear data in particular, impacts radiation exposure health assessments and payload penalty. After a brief review of effects of space radiation on materials and electronics, human space missions to Mars is discussed.

  14. Underwater radiation detector

    DOEpatents

    Kruse, Lyle W. (Albuquerque, NM); McKnight, Richard P. (Albuquerque, NM)

    1986-01-01

    A detector apparatus for differentiating between gamma and neutron radiation is provided. The detector includes a pair of differentially shielded Geiger-Mueller tubes. The first tube is wrapped in silver foil and the second tube is wrapped in lead foil. Both the silver and lead foils allow the passage of gamma rays at a constant rate in a gamma ray only field. When neutrons are present, however, the silver activates and emits beta radiation that is also detected by the silver wrapped Geiger-Mueller tube while the radiation detected by the lead wrapped Geiger-Mueller tube remains constant. The amount of radiation impinging on the separate Geiger-Mueller tubes is then correlated in order to distinguish between the neutron and gamma radiations.

  15. Deployable Heat Pipe Radiator

    NASA Technical Reports Server (NTRS)

    Edelstein, F.

    1975-01-01

    A 1.2- by 1.8-m variable conductance heat pipe radiator was designed, built, and tested. The radiator has deployment capability and can passively control Freon-21 fluid loop temperatures under varying loads and environments. It consists of six grooved variable conductance heat pipes attached to a 0.032-in. aluminum panel. Heat is supplied to the radiator via a fluid header or a single-fluid flexible heat pipe header. The heat pipe header is an artery design that has a flexible section capable of bending up to 90 degrees. Radiator loads as high as 850 watts were successfully tested. Over a load variation of 200 watts, the outlet temperature of the Freon-21 fluid varied by 7 F. An alternate control system was also investigated which used a variable conductance heat pipe header attached to the heat pipe radiator panel.

  16. Radiatively broadened thermal emitters

    E-print Network

    Huppert, Simon; Laurent, Thibault; Todorov, Yanko; Pegolotti, Giulia; Beaudoin, Grégoire; Sagnes, Isabelle; Sirtori, Carlo

    2015-01-01

    We study the incandescence of a semiconductor system characterized by a radiatively broadened material excitation. We show that the shape of the emission spectrum and the peak emissivity value are determined by the ratio between radiative and non-radiative relaxation rates of the material mode. Our system is a heavily doped quantum well, exhibiting a collective bright electronic excitation in the mid-infrared. The spontaneous emission rate of this collective mode strongly depends on the emission direction and, uncommonly for a solid-state system, can dominate non-radiative scattering processes. Consequently the incandescence spectrum undergoes strong modifications when the detection angle is varied. Incandescence is modelled solving quantum Langevin equations, including a microscopic description of the collective excitations, decaying into electronic and photonic baths. We demonstrate that the emissivity reaches unity value for a well-defined direction and presents an angular radiative pattern which is very d...

  17. Fundamentals of Radiation Dosimetry

    SciTech Connect

    Bos, Adrie J. J.

    2011-05-05

    The basic concepts of radiation dosimetry are reviewed on basis of ICRU reports and text books. The radiation field is described with, among others, the particle fluence. Cross sections for indirectly ionizing radiation are defined and indicated is how they are related to the mass energy transfer and mass energy absorption coefficients. Definitions of total and restricted mass stopping powers of directly ionizing radiation are given. The dosimetric quantities, kerma, absorbed dose and exposure together with the relations between them are discussed in depth. Finally it is indicated how the absorbed dose can be measured with a calorimeter by measuring the temperature increase and with an ionisation chamber measuring the charge produced by the ionizing radiation and making use of the Bragg-Gray relation.

  18. Radiation and health.

    PubMed

    Lindell, B

    1987-01-01

    Radiation has been a source of fascination and concern ever since Wilhelm Konrad Röntgen discovered X-rays on 8 November 1895. Over the years, health workers as well as the public have been concerned about medical uses of X-rays, the presence of radon in buildings, radioactive waste from nuclear power stations, fallout from nuclear test explosions, radioactive consumer products, microwave ovens, and many other sources of radiation. Most recently, the tragic accident at the Chernobyl nuclear power station in the USSR, and the subsequent contamination over most of Europe, has again wakened interest and concern and also reminded us about a number of misconceptions about radiation. This article describes the essentials about radiation (especially ionizing radiation) and its health effects. PMID:3496982

  19. RADIATION BIOLOGY: CONCEPTS FOR RADIATION PROTECTION

    EPA Science Inventory

    ABSTRACT

    The opportunity to write a historical review of the field of radiation biology allows for the viewing of the development and maturity of a field of study, thereby being able to provide the appropriate context for the earlier years of research and its findings. The...

  20. Diffusive and Radiative Transport in Fires (DARTFire): Opposed-Flow Flame Spread in Low-Velocity Flows

    NASA Technical Reports Server (NTRS)

    Altenkirch, R. A.; Olson, S. L.; Deering, J. L.; Tang, L.; Bhattacharjee, S.

    1999-01-01

    For flames spreading into a low-velocity flow that can only be obtained in microgravity, we have observed behavior that is different from that which is obtained at higher velocities where radiative effects are unimportant and species transport is relatively fast. Unfortunately, lack of a large body of low-gravity flame spread experimental data inhibits progress in developing an understanding of the physics of low-velocity, opposed-flow flame spread phenomena. Recent DARTFire sounding rocket experimental studies though, coupled with developing theory and modelling, have allowed some strides in understanding to be made, on which we report here. Four launches to date have resulted in six experiments for opposed-flow flame spread over a thick PMMA sample. During the 6 min microgravity period, the PMMA samples were ignited, and steady flame spread was studied under varied flow velocity, oxidizer atmospheric conditions, and, because radiative heat transfer is so important in these slowly spreading flames, external radiant flux. These were the first attempts at such experimental control and measurement in microgravity. A recent reflight of the Solid Surface Combustion Experiment (SSCE) has demonstrated, as modelling predicts, that for the thick fuel of the DARTFire experiment, flame spread in a quiescent environment is a transient process evolving from ignition to extinction on the order of 600 s (Altenkirch et al., 1999). Further study then of the effects of radiation in the very low-velocity opposing flows is of interest in understanding the transition from steady, sustained spread to the unsteady evolution to extinction as the opposing flow is reduced further and eventually removed.

  1. 29 CFR 1910.97 - Nonionizing radiation.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...Nonionizing radiation. (a) Electromagnetic radiation —(1) Definitions...paragraph. (i) The term electromagnetic radiation is restricted to...other possible sources of electromagnetic radiation such as used for...

  2. 29 CFR 1910.97 - Nonionizing radiation.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...Nonionizing radiation. (a) Electromagnetic radiation —(1) Definitions...paragraph. (i) The term electromagnetic radiation is restricted to...other possible sources of electromagnetic radiation such as used for...

  3. 29 CFR 1910.97 - Nonionizing radiation.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...Nonionizing radiation. (a) Electromagnetic radiation —(1) Definitions...paragraph. (i) The term electromagnetic radiation is restricted to...other possible sources of electromagnetic radiation such as used for...

  4. 29 CFR 1910.97 - Nonionizing radiation.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...Nonionizing radiation. (a) Electromagnetic radiation —(1) Definitions...paragraph. (i) The term electromagnetic radiation is restricted to...other possible sources of electromagnetic radiation such as used for...

  5. Solar radiation for Mars power systems

    NASA Technical Reports Server (NTRS)

    Appelbaum, Joseph; Landis, Geoffrey A.

    1991-01-01

    Detailed information about the solar radiation characteristics on Mars are necessary for effective design of future planned solar energy systems operating on the surface of Mars. A procedure and solar radiation related data from which the diurnally and daily variation of the global, direct (or beam), and diffuse insolation on Mars are calculated, are presented. The radiation data are based on measured optical depth of the Martian atmosphere derived from images taken of the Sun with a special diode on the Viking Lander cameras; and computation based on multiple wavelength and multiple scattering of the solar radiation.

  6. Laboratory optical spectroscopy of the thiophenoxy radical and its profile simulation as a diffuse interstellar band based on rotational distribution by radiation and collisions

    SciTech Connect

    Araki, Mitsunori; Niwayama, Kei; Tsukiyama, Koichi

    2014-11-01

    The gas-phase optical absorption spectrum of the thiophenoxy radical (C{sub 6}H{sub 5}S), a diffuse interstellar band (DIB) candidate molecule, was observed in the discharge of thiophenol using a cavity ringdown spectrometer. The ground-state rotational constants of the thiophenoxy radical were theoretically calculated, and the excited-state rotational constants were determined from the observed rotational profile. The rotational profile of a near prolate molecule having C {sub 2v} symmetry was simulated on the basis of a rotational distribution model by radiation and collisions. Although the simulated profile did not agree with the observed DIBs, the upper limit of the column density for the thiophenoxy radical in the diffuse clouds toward HD 204827 was evaluated to be 2 × 10{sup 13} cm{sup –2}. The profile simulation indicates that rotational distribution by radiation and collisions is important to reproduce a rotational profile for a DIB candidate and that the near prolate C {sub 2v} molecule is a possible candidate for DIB with a band width variation dependent on the line of sight.

  7. Radiation Therapy for Testicular Cancer

    MedlinePLUS

    ... chemo and stem cell transplant for testicular cancer Radiation therapy for testicular cancer Radiation therapy uses high-energy rays or particles to ... cells or slow their growth. In testicular cancer, radiation is mainly used to kill cancer cells that ...

  8. Radiation Therapy for Gynecologic Cancers

    MedlinePLUS

    ... care for yourself as well as possible during radiation therapy because the normal parts of your body that ... make sure they are safe to take during radiation therapy. During and even after radiation therapy is over, ...

  9. Radiation Therapy for Lung Cancer

    MedlinePLUS

    ... make sure they are safe to use during radiation therapy. ? Eat a balanced diet. Radiation to the chest should not upset your stomach, ... way you eat. ? Treat the skin exposed to radiation with special care. Wear a shirt when you’ ...

  10. Get the Facts about Radiation

    MedlinePLUS

    ... disclaimer . Subscribe Looking Inside Get the Facts About Radiation Radiation can be dangerous, but it can also save lives. How can that be? Harnessed properly, radiation can help diagnose and even treat disease. So ...

  11. Solar radiation on Mars: Update 1991

    NASA Technical Reports Server (NTRS)

    Appelbaum, Joseph; Landis, Geoffrey A.

    1991-01-01

    Detailed information on solar radiation characteristics on Mars are necessary for effective design of future planned solar energy systems operating on the surface of Mars. A procedure and solar radiation related data are presented from which the daily variation of the global, direct beam and diffuse insolation on Mars are calculated. Given the optical depth of the Mars atmosphere, the global radiation is calculated from the normalized net flux function based on multiple wavelength and multiple scattering of the solar radiation. The direct beam was derived from the optical depth using Beer's law, and the diffuse component was obtained from the difference of the global and the direct beam radiation. The optical depths of the Mars atmosphere were derived from images taken of the Sun with a special diode on the cameras used on the two Viking Landers.

  12. The RAGE radiation-hydrodynamic code

    E-print Network

    Gittings, Michael; Clover, Michael; Betlach, Thomas; Byrne, Nelson; Coker, Robert; Dendy, Edward; Hueckstaedt, Robert; New, Kim; Oakes, W Rob; Ranta, Dale; Stefan, Ryan

    2008-01-01

    We describe RAGE, the ``Radiation Adaptive Grid Eulerian'' radiation-hydrodynamics code, including its data structures, its parallelization strategy and performance, its hydrodynamic algorithm(s), its (gray) radiation diffusion algorithm, and some of the considerable amount of verification and validation efforts. The hydrodynamics is a basic Godunov solver, to which we have made significant improvements to increase the advection algorithm's robustness and to converge stiffnesses in the equation of state. Similarly, the radiation transport is a basic gray diffusion, but our treatment of the radiation-material coupling, wherein we converge nonlinearities in a novel manner to allow larger timesteps and more robust behavior, can be applied to any multi-group transport algorithm.

  13. Beneficial uses of radiation

    SciTech Connect

    Fox, M.R.

    1991-10-01

    An overall decline in technical literacy within the American public has come at a time when technological advances are accelerating in the United States and around the world. This had led to a large communication gulf between the general public and the technologists. Nowhere is this more evident then with the topic of radiation. Regrettably, too few people know about sources of radiation, the pervasiveness, amounts, and variabilities, and do not have a true understanding of the environment in which we live. Nor do many people know that radiation has been used in beneficial ways for decades around the world. While the general public does not know of the scientific applications to which radiation has been deployed, it nevertheless had benefited tremendously from these efforts. Thanks to the well know properties of radiation, scientific ingenuity has found many uses of radiation in chemical and agricultural research, biomedical research, in the diagnoses and treatment of hundreds of types of diseases, in industrial applications, food irradiation, and many others. This paper provides a sample of the types of uses to which radiation has been used to help advance the betterment of humankind.

  14. SYNCHROTRON RADIATION SOURCES

    SciTech Connect

    HULBERT,S.L.; WILLIAMS,G.P.

    1998-07-01

    Synchrotron radiation is a very bright, broadband, polarized, pulsed source of light extending from the infrared to the x-ray region. It is an extremely important source of Vacuum Ultraviolet radiation. Brightness is defined as flux per unit area per unit solid angle and is normally a more important quantity than flux alone particularly in throughput limited applications which include those in which monochromators are used. It is well known from classical theory of electricity and magnetism that accelerating charges emit electromagnetic radiation. In the case of synchrotron radiation, relativistic electrons are accelerated in a circular orbit and emit electromagnetic radiation in a broad spectral range. The visible portion of this spectrum was first observed on April 24, 1947 at General Electric's Schenectady facility by Floyd Haber, a machinist working with the synchrotron team, although the first theoretical predictions were by Lienard in the latter part of the 1800's. An excellent early history with references was presented by Blewett and a history covering the development of the utilization of synchrotron radiation was presented by Hartman. Synchrotron radiation covers the entire electromagnetic spectrum from the infrared region through the visible, ultraviolet, and into the x-ray region up to energies of many 10's of kilovolts. If the charged particles are of low mass, such as electrons, and if they are traveling relativistically, the emitted radiation is very intense and highly collimated, with opening angles of the order of 1 milliradian. In electron storage rings there are three possible sources of synchrotron radiation; dipole (bending) magnets; wigglers, which act like a sequence of bending magnets with alternating polarities; and undulators, which are also multi-period alternating magnet systems but in which the beam deflections are small resulting in coherent interference of the emitted light.

  15. Stimulated coherent transition radiation

    SciTech Connect

    Hung-chi Lihn

    1996-03-01

    Coherent radiation emitted from a relativistic electron bunch consists of wavelengths longer than or comparable to the bunch length. The intensity of this radiation out-numbers that of its incoherent counterpart, which extends to wavelengths shorter than the bunch length, by a factor equal to the number of electrons in the bunch. In typical accelerators, this factor is about 8 to 11 orders of magnitude. The spectrum of the coherent radiation is determined by the Fourier transform of the electron bunch distribution and, therefore, contains information of the bunch distribution. Coherent transition radiation emitted from subpicosecond electron bunches at the Stanford SUNSHINE facility is observed in the far-infrared regime through a room-temperature pyroelectric bolometer and characterized through the electron bunch-length study. To measure the bunch length, a new frequency-resolved subpicosecond bunch-length measuring system is developed. This system uses a far-infrared Michelson interferometer to measure the spectrum of coherent transition radiation through optical autocorrelation with resolution far better than existing time-resolved methods. Hence, the radiation spectrum and the bunch length are deduced from the autocorrelation measurement. To study the stimulation of coherent transition radiation, a special cavity named BRAICER is invented. Far-infrared light pulses of coherent transition radiation emitted from electron bunches are delayed and circulated in the cavity to coincide with subsequent incoming electron bunches. This coincidence of light pulses with electron bunches enables the light to do work on electrons, and thus stimulates more radiated energy. The possibilities of extending the bunch-length measuring system to measure the three-dimensional bunch distribution and making the BRAICER cavity a broadband, high-intensity, coherent, far-infrared light source are also discussed.

  16. Synchrotron radiation sources and research

    SciTech Connect

    Teng, L.C.

    1995-12-31

    This is an introduction and a review of Synchrotron Radiation sources and the research performed using synchrotron radiation. I will begin with a brief discussion of the two principal uses of particle storage rings: for colliding beams (Collider) and for synchrotron radiation (Radiator). Then I will concentrate on discussions of synchrotron radiation topics, starting with a historical account, followed by descriptions of the features of the storage ring and the features of the radiation from the simplest source -- the bending magnet. I will then discuss the special insertion device sources -- wigglers and undulators -- and their radiations, and end with a brief general account of the research and other applications of synchrotron radiation.

  17. American Society for Radiation Oncology

    MedlinePLUS

    ... Resources and Links Journals Practice Management Practice Accreditation Radiation Oncology Coding Reimbursement PQRS EHR Incentives Program National Radiation Oncology Registry Advocacy What's Happening in Washington? What's ...

  18. Radiation Safety System

    SciTech Connect

    Vylet, Vaclav; Liu, James C.; Walker, Lawrence S.; /Los Alamos

    2012-04-04

    The goal of this work is to provide an overview of a Radiation safety system (RSS) designed for protection from prompt radiation hazard at accelerator facilities. RSS design parameters, functional requirements and constraints are derived from hazard analysis and risk assessment undertaken in the design phase of the facility. The two main subsystems of a RSS are access control system (ACS) and radiation control system (RCS). In this text, a common approach to risk assessment, typical components of ACS and RCS, desirable features and general design principles applied to RSS are described.

  19. Human radiation tolerance

    NASA Technical Reports Server (NTRS)

    Lushbaugh, C. C.

    1974-01-01

    The acute radiation syndrome in man is clinically bounded by death at high dose levels and by the prodromal syndrome of untoward physiological effects at minimal levels of clinically effective exposure. As in lower animals, man experiences principally three acute modes of death from radiation exposure (Bond et al., 1965). These are known collectively as the lethal radiation syndromes: central nervous system death, gastrointestinal death, and hematopoietic death. The effect of multiple exposure on lethality, the effect of multiple exposure on hematopoietic recovery, and quantitative aspects of cell and tissue repair are discussed.

  20. Miniaturized radiation chirper

    DOEpatents

    Umbarger, C. John (Los Alamos, NM); Wolf, Michael A. (Los Alamos, NM)

    1980-01-01

    The disclosure relates to a miniaturized radiation chirper for use with a small battery supplying on the order of 5 volts. A poor quality CdTe crystal which is not necessarily suitable for high resolution gamma ray spectroscopy is incorporated with appropriate electronics so that the chirper emits an audible noise at a rate that is proportional to radiation exposure level. The chirper is intended to serve as a personnel radiation warning device that utilizes new and novel electronics with a novel detector, a CdTe crystal. The resultant device is much smaller and has much longer battery life than existing chirpers.

  1. Radiative forcing of climate

    NASA Technical Reports Server (NTRS)

    Ramanswamy, V.; Shine, Keith; Leovy, Conway; Wang, Wei-Chyung; Rodhe, Henning; Wuebbles, Donald J.; Ding, M.; Lelieveld, Joseph; Edmonds, Jae A.; Mccormick, M. Patrick

    1991-01-01

    An update of the scientific discussions presented in Chapter 2 of the Intergovernmental Panel on Climate Change (IPCC) report is presented. The update discusses the atmospheric radiative and chemical species of significance for climate change. There are two major objectives of the present update. The first is an extension of the discussion on the Global Warming Potentials (GWP's), including a reevaluation in view of the updates in the lifetimes of the radiatively active species. The second important objective is to underscore major developments in the radiative forcing of climate due to the observed stratospheric ozone losses occurring between 1979 and 1990.

  2. Microcircuit radiation effects databank

    NASA Technical Reports Server (NTRS)

    1983-01-01

    This databank is the collation of radiation test data submitted by many testers and serves as a reference for engineers who are concerned with and have some knowledge of the effects of the natural radiation environment on microcircuits. It contains radiation sensitivity results from ground tests and is divided into two sections. Section A lists total dose damage information, and section B lists single event upset cross sections, I.E., the probability of a soft error (bit flip) or of a hard error (latchup).

  3. Liquid sheet radiator

    NASA Technical Reports Server (NTRS)

    Chubb, Donald L.; White, K. Alan, III

    1987-01-01

    A new external flow radiator concept, the liquid sheet radiator (LSR), is introduced. The LSR sheet flow is described and an expression for the length/width (l/w), ratio is presented. A linear dependence of l/w on velocity is predicted that agrees with experimental results. Specific power for the LSR is calculated and is found to be nearly the same as the specific power of a liquid droplet radiator, (LDR). Several sheet thicknesses and widths were experimentally investigated. In no case was the flow found to be unstable.

  4. Composition for radiation shielding

    DOEpatents

    Kronberg, James W. (Aiken, SC)

    1994-01-01

    A composition for use as a radiation shield. The shield has a depleted urum core for absorbing gamma rays and a bismuth coating for preventing chemical corrosion and absorbing gamma rays. Alternatively, a sheet of gadolinium may be positioned between the uranium core and the bismuth coating for absorbing neutrons. The composition is preferably in the form of a container for storing materials that emit radiation such as gamma rays and neutrons. The container is preferably formed by casting bismuth around a pre-formed uranium container having a gadolinium sheeting, and allowing the bismuth to cool. The resulting container is a structurally sound, corrosion-resistant, radiation-absorbing container.

  5. I. RADIATION AND BACKGROUNDS A. Conventional Radiation

    E-print Network

    McDonald, Kirk

    of radius ß 15 m. If any water were present in the soil/rock then the first two meters around the aborted radiation dose DB (Sv) over a time t(s), in the plane of a bending magnet of field B(T), in a circular collider with beam energy E(TeV ), average bending field ! B(T ) ?, at a depth d(m) (assuming a spherical

  6. Nanotechnology in Radiation Oncology

    PubMed Central

    Wang, Andrew Z.; Tepper, Joel E.

    2014-01-01

    Nanotechnology, the manipulation of matter on atomic and molecular scales, is a relatively new branch of science. It has already made a significant impact on clinical medicine, especially in oncology. Nanomaterial has several characteristics that are ideal for oncology applications, including preferential accumulation in tumors, low distribution in normal tissues, biodistribution, pharmacokinetics, and clearance, that differ from those of small molecules. Because these properties are also well suited for applications in radiation oncology, nanomaterials have been used in many different areas of radiation oncology for imaging and treatment planning, as well as for radiosensitization to improve the therapeutic ratio. In this article, we review the unique properties of nanomaterials that are favorable for oncology applications and examine the various applications of nanotechnology in radiation oncology. We also discuss the future directions of nanotechnology within the context of radiation oncology. PMID:25113769

  7. Amorphous silicon radiation detectors

    DOEpatents

    Street, Robert A. (Palo Alto, CA); Perez-Mendez, Victor (Berkeley, CA); Kaplan, Selig N. (El Cerrito, CA)

    1992-01-01

    Hydrogenated amorphous silicon radiation detector devices having enhanced signal are disclosed. Specifically provided are transversely oriented electrode layers and layered detector configurations of amorphous silicon, the structure of which allow high electric fields upon application of a bias thereby beneficially resulting in a reduction in noise from contact injection and an increase in signal including avalanche multiplication and gain of the signal produced by incoming high energy radiation. These enhanced radiation sensitive devices can be used as measuring and detection means for visible light, low energy photons and high energy ionizing particles such as electrons, x-rays, alpha particles, beta particles and gamma radiation. Particular utility of the device is disclosed for precision powder crystallography and biological identification.

  8. Ionizing radiation detector

    DOEpatents

    Thacker, Louis H. (Knoxville, TN)

    1990-01-01

    An ionizing radiation detector is provided which is based on the principle of analog electronic integration of radiation sensor currents in the sub-pico to nano ampere range between fixed voltage switching thresholds with automatic voltage reversal each time the appropriate threshold is reached. The thresholds are provided by a first NAND gate Schmitt trigger which is coupled with a second NAND gate Schmitt trigger operating in an alternate switching state from the first gate to turn either a visible or audible indicating device on and off in response to the gate switching rate which is indicative of the level of radiation being sensed. The detector can be configured as a small, personal radiation dosimeter which is simple to operate and responsive over a dynamic range of at least 0.01 to 1000 R/hr.

  9. Amorphous silicon radiation detectors

    DOEpatents

    Street, R.A.; Perez-Mendez, V.; Kaplan, S.N.

    1992-11-17

    Hydrogenated amorphous silicon radiation detector devices having enhanced signal are disclosed. Specifically provided are transversely oriented electrode layers and layered detector configurations of amorphous silicon, the structure of which allow high electric fields upon application of a bias thereby beneficially resulting in a reduction in noise from contact injection and an increase in signal including avalanche multiplication and gain of the signal produced by incoming high energy radiation. These enhanced radiation sensitive devices can be used as measuring and detection means for visible light, low energy photons and high energy ionizing particles such as electrons, x-rays, alpha particles, beta particles and gamma radiation. Particular utility of the device is disclosed for precision powder crystallography and biological identification. 13 figs.

  10. Space radiation studies

    NASA Technical Reports Server (NTRS)

    Gregory, J. C.

    1986-01-01

    Instrument design and data analysis expertise was provided in support of several space radiation monitoring programs. The Verification of Flight Instrumentation (VFI) program at NASA included both the Active Radiation Detector (ARD) and the Nuclear Radiation Monitor (NRM). Design, partial fabrication, calibration and partial data analysis capability to the ARD program was provided, as well as detector head design and fabrication, software development and partial data analysis capability to the NRM program. The ARD flew on Spacelab-1 in 1983, performed flawlessly and was returned to MSFC after flight with unchanged calibration factors. The NRM, flown on Spacelab-2 in 1985, also performed without fault, not only recording the ambient gamma ray background on the Spacelab, but also recording radiation events of astrophysical significance.

  11. Radiation Therapy for Cancer

    MedlinePLUS

    ... radioactive isotopes are sealed in tiny pellets or “seeds.” These seeds are placed in patients using delivery devices, such ... completely and no longer give off radiation. The seeds will not cause harm if they are left ...

  12. [Genetic effects of radiation].

    PubMed

    Nakamura, Nori

    2012-03-01

    This paper is a short review of genetic effect of radiation. This includes methods and results of a large-scale genetic study on specific loci in mice and of various studies in the offspring of atomic-bomb survivors. As for the latter, there is no results obtained which suggest the effect of parental exposure to radiation. Further, in recent years, studies are conducted to the offspring born to parents who were survivors of childhood cancers. In several reports, the mean gonad dose is quite large whereas in most instances, the results do not indicate genetic effect following parental exposure to radiation. Possible reasons for the difficulties in detecting genetic effect of radiation are discussed. PMID:22514926

  13. Calculate Your Radiation Dose

    MedlinePLUS

    ... your County: Loading... This state has no counties. ESTIMATED TOTAL YEARLY DOSE (in mrem) Your result is ... general averages, and should be used to compare estimated doses from common sources of radiation. For most ...

  14. Radiation - Duration: 31 seconds.

    NASA Video Gallery

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

  15. Occupational Radiation Exposures

    Cancer.gov

    DCEG researchers are studying cancer risks among populations who are occupationally exposed to radiation. Chernobyl Clean-up Workers Mayak Nuclear Facility Workers U.S. Radiologic Technologists Interventional Fluoroscopists Print This Page Occupational

  16. SOLAR RADIATION, VA

    EPA Science Inventory

    Sterling, Virginia Integrated Surface Irradiance Study (ISIS) solar radiation data files from National Oceanic and Atmospheric Administration (NOAA), zipped from ftp://ftp.atdd.noaa.gov/pub/projects/isis/ste/monthly

  17. Radiation risks in pregnancy

    SciTech Connect

    Mossman, K.L.; Hill, L.T.

    1982-08-01

    A major contraindication of radiodiagnostic procedures is pregnancy. Approximately 1% of all pregnant women are given abdominal x-rays during the first trimester of pregnancy. Evaluation of radiation exposure should involve consideration of the types of examinations performed and when performed, as well as radiation dose and risk estimation. This information is then weighed against other possible risks of the pregnancy as well as personal factors. In the authors' experiences, radiation exposures usually result in doses to the embryo of less than 5 cGy (rad); the resulting radiation risks are usually small compared with other risks of pregnancy. Procedures to minimize diagnostic x-ray exposure of the fetus are also discussed.

  18. Portal radiation monitor

    SciTech Connect

    Kruse, Lyle W.

    1985-01-01

    A portal radiation monitor combines 0.1% FAR with high sensitivity to special nuclear material. The monitor utilizes pulse shape discrimination, dynamic compression of the photomultiplier output and scintillators sized to maintain efficiency over the entire portal area.

  19. Portal radiation monitor

    DOEpatents

    Kruse, L.W.

    1982-03-23

    A portal radiation monitor combines .1% FAR with high sensitivity to special nuclear material. The monitor utilizes pulse shape discrimination, dynamic compression of the photomultiplier output and scintillators sized to maintain efficiency over the entire portal area.

  20. Prostate radiation - discharge

    MedlinePLUS

    Basics of radiation therapy. In: Niederhuber JE, Armitage JO, Doroshow JH, Kastan MB, Tepper JE, eds. Abeloff's Clinical Oncology . 5th ed. Philadelphia, PA: Elsevier Churchill Livingstone; 2013:chap 27. D'Amico ...

  1. Tin Can Radiation Detector.

    ERIC Educational Resources Information Center

    Crull, John L.

    1986-01-01

    Provides instructions for making tin can radiation detectors from empty aluminum cans, aluminum foil, clear plastic, copper wire, silica gel, and fine, unwaxed dental floss put together with tape or glue. Also provides suggestions for activities using the detectors. (JN)

  2. The Space Radiation Environment

    NASA Technical Reports Server (NTRS)

    Bourdarie, Sebastien; Xapsos, Michael A.

    2008-01-01

    The effects of the space radiation environment on spacecraft systems and instruments are significant design considerations for space missions. Astronaut exposure is a serious concern for manned missions. In order to meet these challenges and have reliable, cost-effective designs, the radiation environment must be understood and accurately modeled. The nature of the environment varies greatly between low earth orbits, higher earth orbits and interplanetary space. There are both short-term and long-term variations with the phase of the solar cycle. In this paper we concentrate mainly on charged particle radiations. Descriptions of the radiation belts and particles of solar and cosmic origin are reviewed. An overview of the traditional models is presented accompanied by their application areas and limitations. This is followed by discussion of some recent model developments.

  3. Method of enhancing radiation response of radiation detection materials

    DOEpatents

    Miller, Steven D. (Richland, WA)

    1997-01-01

    The present invention is a method of increasing radiation response of a radiation detection material for a given radiation signal by first pressurizing the radiation detection material. Pressurization may be accomplished by any means including mechanical and/or hydraulic. In this application, the term "pressure" includes fluid pressure and/or mechanical stress.

  4. Radiation pressure driving of a dusty atmosphere

    NASA Astrophysics Data System (ADS)

    Tsang, Benny T.-H.; Milosavljevi?, Miloš

    2015-10-01

    Radiation pressure can be dynamically important in star-forming environments such as ultra-luminous infrared and submillimetre galaxies. Whether and how radiation drives turbulence and bulk outflows in star formation sites is still unclear. The uncertainty in part reflects the limitations of direct numerical schemes that are currently used to simulate radiation transfer and radiation-gas coupling. An idealized setup in which radiation is introduced at the base of a dusty atmosphere in a gravitational field has recently become the standard test for radiation-hydrodynamics methods in the context of star formation. To a series of treatments featuring the flux-limited diffusion approximation as well as a short-characteristics tracing and M1 closure for the variable Eddington tensor approximation, we here add another treatment that is based on the implicit Monte Carlo radiation transfer scheme. Consistent with all previous treatments, the atmosphere undergoes Rayleigh-Taylor instability and readjusts to a near-Eddington-limited state. We detect late-time net acceleration in which the turbulent velocity dispersion matches that reported previously with the short-characteristics-based radiation transport closure, the most accurate of the three preceding treatments. Our technical result demonstrates the importance of accurate radiation transfer in simulations of radiative feedback.

  5. Advanced radiation protection?

    NASA Astrophysics Data System (ADS)

    Jones, Robert

    2014-03-01

    In order to have radiation-free nuclear reactions (the purported LENRs) it would be necessary that ``...one could fractionate large MeV quanta into millions or even billions of smaller quanta.'' (P. L. Hagelstein, Infinite Energy, issue 112, page 12, 2013). See also my sci.physics.fusion post of 1 April 2004 and Kan. Sci. Teacher, vol. 7, 12, 1990. If one had such a mechanism it might be even more important for use as general radiation shielding.

  6. Test problems for radiation and radiation-hydrodynamics codes

    SciTech Connect

    Ensman, L.

    1994-03-01

    A number of test problems for radiation and radiation-hydrodynamics computer codes are described. These include evolution to radiative equilibrium, cooling from radiative equilibrium, subcritical and supercritical radiating shocks, and a radiating blast wave in a power-law density distribution. For each test problem, example input parameters and plots of the results are presented. Some test problems for pure hydrodynamics are also suggested. The radiation-hydrodynamics code used to perform the example test problems and the equations it solves are described in some detail.

  7. Numerical Radiative Transfer

    NASA Astrophysics Data System (ADS)

    Kalkofen, Wolfgang

    2009-07-01

    Preface; Introduction; Part I. Operator Perturbation: 1. Survey of operator perturbation methods W. Kalkofen; 2. Line formation in expanding atmospheres: multilevel calculations using approximate lambda operators W. R. Hamann; 3. Stellar atmospheres in non-LTE: model construction and line formation calculations using approximate lambda operators K. Werner; 4. Acceleration of convergence L. H. Auer; 5. Line formation in a time-dependent atmosphere W. Kalkofen; 6. Iterative solution of multilevel transfer problems Eugene H. Avrett and Rudolf Loeser; 7. An algorithm for the simultaneous solution of thousands of transfer equations under global constraints Lawrence S. Anderson; 8. Operator perturbation for differential equations W. Kalkofen; Part II. Polarised Radiation: 9. A gentle introduction to polarised radiative transfer David E. Rees; 10. Non-LTE polarised radiative transfer in special lines David E. Rees and Graham A. Murphy; 11. Transfer of polarised radiation using 4x4 matrices E. Landi Degli'Innocenti; 12. Radiative transfer in the presence of strong magnetic fields A. A. van Ballegooijen; 13. An integral operator technique of radiative transfer in spherical symmetry A. Peraiah; 14. Discrete ordinate matrix method M. Schmidt and R. Wehrse.

  8. Fabric space radiators

    SciTech Connect

    Antoniak, Z.I.; Krotiuk, W.J.; Webb, B.J.; Prater, J.T.; Bates, J.M.

    1988-01-01

    Future Air Force space missions will require thermal radiators that both survive in the hostile space environment and stow away for minimal bulk during launch. Advances in all aspects of radiator design, construction, and analysis will be necessary to enable such future missions. Currently, the best means for obtaining high strength along with flexibility is through structures known as fabrics. The development of new materials and bonding techniques has extended the application range of fabrics into areas traditionally dominated by monolithic and/or metallic structures. Given that even current spacecraft heat rejection considerations tend to dominate spacecraft design and mass, the larger and more complex designs of the future face daunting challenges in thermal control. Ceramic fabrics bonded to ultra-thin metal liners (foils) have the potential of achieving radiator performance levels heretofore unattainable, and of readily matching the advances made in other branches of spacecraft design. The research effort documented here indicates that both pumped loops and heat pipes constructed in ceramic fabrics stand to benefit in multiple ways. Flexibility and low mass are the main advantages exhibited by fabric radiators over conventional metal ones. We feel that fabric radiators have intrinsic merits not possessed by any other radiator design and need to be researched further. 26 refs., 16 figs., 17 tabs.

  9. Packet personal radiation monitor

    DOEpatents

    Phelps, James E. (Knoxville, TN)

    1989-01-01

    A personal radiation monitor of the chirper type is provided for detecting ionizing radiation. A battery powered high voltage power supply is used to generate and apply a high voltage bias to a G-M tube radiation sensor. The high voltage is monitored by a low-loss sensing network which generates a feedback signal to control the high voltage power supply such that the high voltage bias is recharged to +500 VDC when the current pulses of the sensor, generated by the detection of ionizing radiation events, discharges the high voltage bias to +450 VDC. During the high voltage recharge period an audio transducer is activated to produce an audible "chirp". The rate of the "chirps" is controlled by the rate at which the high voltage bias is recharged, which is proportional to the radiation field intensity to which the sensor is exposed. The chirp rate sensitivity is set to be approximately 1.5 (chirps/min/MR/hr.). The G-M tube sensor is used in a current sensing mode so that the device does not paralyze in a high radiation field.

  10. Acute radiation syndrome caused by accidental radiation exposure - therapeutic principles

    PubMed Central

    2011-01-01

    Fortunately radiation accidents are infrequent occurrences, but since they have the potential of large scale events like the nuclear accidents of Chernobyl and Fukushima, preparatory planning of the medical management of radiation accident victims is very important. Radiation accidents can result in different types of radiation exposure for which the diagnostic and therapeutic measures, as well as the outcomes, differ. The clinical course of acute radiation syndrome depends on the absorbed radiation dose and its distribution. Multi-organ-involvement and multi-organ-failure need be taken into account. The most vulnerable organ system to radiation exposure is the hematopoietic system. In addition to hematopoietic syndrome, radiation induced damage to the skin plays an important role in diagnostics and the treatment of radiation accident victims. The most important therapeutic principles with special reference to hematopoietic syndrome and cutaneous radiation syndrome are reviewed. PMID:22114866

  11. Radiation analysis devices, radiation analysis methods, and articles of manufacture

    DOEpatents

    Roybal, Lyle Gene

    2010-06-08

    Radiation analysis devices include circuitry configured to determine respective radiation count data for a plurality of sections of an area of interest and combine the radiation count data of individual of sections to determine whether a selected radioactive material is present in the area of interest. An amount of the radiation count data for an individual section is insufficient to determine whether the selected radioactive material is present in the individual section. An article of manufacture includes media comprising programming configured to cause processing circuitry to perform processing comprising determining one or more correction factors based on a calibration of a radiation analysis device, measuring radiation received by the radiation analysis device using the one or more correction factors, and presenting information relating to an amount of radiation measured by the radiation analysis device having one of a plurality of specified radiation energy levels of a range of interest.

  12. Radiative heat transfer in plastic welding process

    NASA Astrophysics Data System (ADS)

    Kurosaki, Yasuo

    2005-06-01

    This paper deals with a novel CO2 laser plastic welding procedure developed from the point of view of heat transfer containing simultaneous radiation and conduction processes and also gives a brief review of plastic welding development to date. The principle and features are shown by both the experiments using CO2 laser as a radiation source and numerical simulation considering heat transfer phenomena in simultaneous radiation and conduction in welding process. The feasibility of the proposed procedure is confirmed by applying the overlapped same plastic films with combination of infrared radiation absorbing heating and thermal diffusion cooling processes. A solid material transparent to infrared radiation with a high thermal diffusivity is used as a heat sink in contact with the irradiated surface of overlapped thermoplastics during radiation heating. The procedure is able to achieve both high welding strength and excellent surface appearance without causing surface thermal damage as often suffered in conventional direct infrared radiation welding process. In addition, pigmentation in welding material to increase absorption of radiation is unnecessary for this method.

  13. The Gilbert Beebe Radiation Fellowship

    Cancer.gov

    Description of the Gilbert Beebe Radiation Fellowship for mid- to senior-level epidemiologists or biostatisticians. Recipients work in the Radiation Epidemiology Branch of the National Cancer Institute and the Radiation Effects Research Foundation (RERF) in Hiroshima, Japan on research related to the atomic bomb survivors and other radiation topics.

  14. Radiation Sensitization in Cancer Therapy.

    ERIC Educational Resources Information Center

    Greenstock, Clive L.

    1981-01-01

    Discusses various aspects of radiation damage to biological material, including free radical mechanisms, radiation sensitization and protection, tumor hypoxia, mechanism of hypoxic cell radiosensitization, redox model for radiation modification, sensitizer probes of cellular radiation targets, pulse radiolysis studies of free radical kinetics,…

  15. Radiation nephritis causing nephrotic syndrome

    SciTech Connect

    Jennette, J.C.; Ordonez, N.G.

    1983-12-01

    Clinical symptoms of acute radiation nephritis with nephrotic syndrome developed in a fifty-six-year-old woman after abdominal radiation therapy for an astrocytoma of the spinal cord. The diagnosis of radiation nephritis was confirmed by renal biopsy. To our knowledge, this is the first documented case of radiation nephritis associated with nephrotic syndrome.

  16. Radiation Protection Guidance Hospital Staff

    E-print Network

    Kay, Mark A.

    with radioactive materials or radiation devices are responsible for knowing and adhering to applicable requirements. The Radiation Safety Officer is responsible for managing the radiation safety program subject to the approvalPage 1 Radiation Protection Guidance For Hospital Staff Prepared for Stanford

  17. Radiation health research, 1986 - 1990

    NASA Technical Reports Server (NTRS)

    1991-01-01

    A collection of 225 abstracts of radiation research sponsored by NASA during the period 1986 through 1990 is reported. Each abstract was categorized within one of four discipline areas: physics, biology, risk assessment, and microgravity. Topic areas within each discipline were assigned as follows: Physics - atomic physics, nuclear science, space radiation, radiation transport and shielding, and instrumentation; Biology - molecular biology, cellular radiation biology, tissue, organs and organisms, radioprotectants, and plants; Risk assessment - radiation health and epidemiology, space flight radiation health physics, inter- and intraspecies extrapolation, and radiation limits and standards; and Microgravity. When applicable subareas were assigned for selected topic areas. Keywords and author indices are provided.

  18. Bile Duct (Cholangiocarcinoma) Cancer: Radiation Therapy

    MedlinePLUS

    ... cancer Next Topic Chemotherapy for bile duct cancer Radiation therapy for bile duct cancer Radiation therapy uses ... of radiation for bile duct cancer. External beam radiation therapy (EBRT) This type of radiation therapy uses ...

  19. Radiation in Particle Simulations

    SciTech Connect

    More, R; Graziani, F; Glosli, J; Surh, M

    2010-11-19

    Hot dense radiative (HDR) plasmas common to Inertial Confinement Fusion (ICF) and stellar interiors have high temperature (a few hundred eV to tens of keV), high density (tens to hundreds of g/cc) and high pressure (hundreds of megabars to thousands of gigabars). Typically, such plasmas undergo collisional, radiative, atomic and possibly thermonuclear processes. In order to describe HDR plasmas, computational physicists in ICF and astrophysics use atomic-scale microphysical models implemented in various simulation codes. Experimental validation of the models used to describe HDR plasmas are difficult to perform. Direct Numerical Simulation (DNS) of the many-body interactions of plasmas is a promising approach to model validation but, previous work either relies on the collisionless approximation or ignores radiation. We present four methods that attempt a new numerical simulation technique to address a currently unsolved problem: the extension of molecular dynamics to collisional plasmas including emission and absorption of radiation. The first method applies the Lienard-Weichert solution of Maxwell's equations for a classical particle whose motion is assumed to be known. The second method expands the electromagnetic field in normal modes (planewaves in a box with periodic boundary-conditions) and solves the equation for wave amplitudes coupled to the particle motion. The third method is a hybrid molecular dynamics/Monte Carlo (MD/MC) method which calculates radiation emitted or absorbed by electron-ion pairs during close collisions. The fourth method is a generalization of the third method to include small clusters of particles emitting radiation during close encounters: one electron simultaneously hitting two ions, two electrons simultaneously hitting one ion, etc. This approach is inspired by the virial expansion method of equilibrium statistical mechanics. Using a combination of these methods we believe it is possible to do atomic-scale particle simulations of fusion ignition plasmas including the important effects of radiation emission and absorption.

  20. Status of LDEF radiation modeling

    NASA Technical Reports Server (NTRS)

    Watts, John W.; Armstrong, T. W.; Colborn, B. L.

    1995-01-01

    The current status of model prediction and comparison with LDEF radiation dosimetry measurements is summarized with emphasis on major results obtained in evaluating the uncertainties of present radiation environment model. The consistency of results and conclusions obtained from model comparison with different sets of LDEF radiation data (dose, activation, fluence, LET spectra) is discussed. Examples where LDEF radiation data and modeling results can be utilized to provide improved radiation assessments for planned LEO missions (e.g., Space Station) are given.

  1. Radiation delivery system and method

    DOEpatents

    Sorensen, Scott A. (Overland Park, KS); Robison, Thomas W. (Los Alamos, NM); Taylor, Craig M. V. (Jemez Springs, NM)

    2002-01-01

    A radiation delivery system and method are described. The system includes a treatment configuration such as a stent, balloon catheter, wire, ribbon, or the like, a portion of which is covered with a gold layer. Chemisorbed to the gold layer is a radiation-emitting self-assembled monolayer or a radiation-emitting polymer. The radiation delivery system is compatible with medical catheter-based technologies to provide a therapeutic dose of radiation to a lesion following an angioplasty procedure.

  2. The Role of Diffusion-Weighted Magnetic Resonance Imaging in the Treatment Response Evaluation of Hepatocellular Carcinoma Patients Treated With Radiation Therapy

    SciTech Connect

    Yu, Jeong Il; Park, Hee Chul; Lim, Do Hoon; Choi, Yunseon; Jung, Sang Hoon; Paik, Seung Woon; Kim, Seong Hyun; Jeong, Woo Kyoung; Kim, Young Kon

    2014-07-15

    Purpose: We investigated the role of diffusion-weighted magnetic resonance imaging (DW MRI) as a response evaluation indicator for hepatocellular carcinoma (HCC) treated with radiation therapy (RT). Methods and Materials: Inclusion criteria of this retrospective study were DW MRI acquisition within 1 month before and 3 to 5 months after RT. In total, 48 patients were enrolled. Two radiation oncologists measured the apparent diffusion coefficient (ADC). Possible predictive factors, including alteration of the ADC value before and 3 to 5 month after RT, in relation to local progression-free survival (LPFS) were analyzed and compared. Results: Three months after RT, 6 patients (12.5%) showed a complete response, and 27 patients (56.3%) showed a partial response when evaluated using the modified response evaluation criteria in solid tumors (mRECIST). The average ADC ± SD values were 1.21 ± 0.27 ( × 10{sup ?3} mm{sup 2}/s) before and 1.41 ± 0.36 ( × 10{sup ?3} mm{sup 2}/s) after RT (P<.001). The most significant prognostic factor related to LPFS was mRECIST (P<.001). The increment of ADC value (?20%) was also a significant factor (P=.02), but RECIST (version 1.1; P=.11) was not. When RECIST was combined with the increment of ADC value (?20%), the LPFS rates were significantly different between the groups (P=.004), and the area under the curve value (0.745) was comparable with that of mRECIST (0.765). Conclusions: ADC value change before and after RT in HCC was closely related to LPFS. ADC value and RECIST may substitute for mRECIST in patients who cannot receive contrast agents.

  3. Multiscale Modeling of Radiation ResponseMultiscale Modeling of Radiation ResponseMultiscale Modeling of Radiation ResponseMultiscale Modeling of Radiation Response Effects of Radiation Quality and HypoxiaEffects of Radiation Quality and Hypoxia

    E-print Network

    Stewart, Robert D.

    the spectrum of DNA damages formed by ionizing radiation. Radiat Res. 161(4), 451-457 (2004) · R.D. Stewart, WMultiscale Modeling of Radiation ResponseMultiscale Modeling of Radiation ResponseMultiscale Modeling of Radiation ResponseMultiscale Modeling of Radiation Response Effects of Radiation Quality

  4. Ocular temperature elevation induced by threshold in vivo exposure to 1090-nm infrared radiation and associated heat diffusion

    NASA Astrophysics Data System (ADS)

    Yu, Zhaohua; Schulmeister, Karl; Talebizadeh, Nooshin; Kronschläger, Martin; Söderberg, Per G.

    2014-10-01

    An in vivo exposure to 197 W/cm2 1090-nm infrared radiation (IRR) requires a minimum 8 s for cataract induction. The present study aims to determine the ocular temperature evolution and the associated heat flow at the same exposure conditions. Two groups of 12 rats were unilaterally exposed within the dilated pupil with a close to collimated beam between lens and retina. Temperature was recorded with thermocouples. Within 5 min after exposure, the lens light scattering was measured. In one group, the temperature rise in the exposed eye, expressed as a confidence interval (0.95), was 11±3°C at the limbus, 16±6°C in the vitreous behind lens, and 16±7°C on the sclera next to the optic nerve, respectively. In the other group, the temperature rise in the exposed eye was 9±1°C at the limbus and 26±11°C on the sclera next to the optic nerve, respectively. The difference of forward light scattering between exposed and contralateral not exposed eye was 0.01±0.09 tEDC. An exposure to 197 W/cm2 1090-nm IRR for 8 s induces a temperature increase of 10°C at the limbus and 26°C close to the retina. IRR cataract is probably of thermal origin.

  5. Deconstructing radiation hormesis.

    PubMed

    Mossman, K L

    2001-03-01

    This paper explores some factors that may explain why the possibility of hormesis has not been embraced by the radiation protection community. If shown to be sustainable, hormesis might ameliorate several serious issues plaguing radiation protection including the high economic cost of environmental regulatory compliance and public fear of radiation exposure. Some but not all analyses of data from various sources, including the Japanese survivors of the atomic bombs and residential radon studies, suggest that low levels of ionizing radiation may be beneficial to human health. The evidence, however, has not been viewed as compelling for the following reasons: (1) Data in support of radiation hormesis in human populations is limited and much of it is based on re-evaluation of selected epidemiological data that has been used to test a different hypothesis; (2) Hormetic effects are weak and inconsistent, and are subject to large statistical uncertainties as is the case for carcinogenic effects at small doses; (3) A consensus is lacking on how hormesis should be defined and quantified; and (4) It is unclear how hormesis can be incorporated into the regulatory framework when beneficial health effects exceed the requirement for protection of health. PMID:11219539

  6. Ionizing radiation and life.

    PubMed

    Dartnell, Lewis R

    2011-01-01

    Ionizing radiation is a ubiquitous feature of the Cosmos, from exogenous cosmic rays (CR) to the intrinsic mineral radioactivity of a habitable world, and its influences on the emergence and persistence of life are wide-ranging and profound. Much attention has already been focused on the deleterious effects of ionizing radiation on organisms and the complex molecules of life, but ionizing radiation also performs many crucial functions in the generation of habitable planetary environments and the origins of life. This review surveys the role of CR and mineral radioactivity in star formation, generation of biogenic elements, and the synthesis of organic molecules and driving of prebiotic chemistry. Another major theme is the multiple layers of shielding of planetary surfaces from the flux of cosmic radiation and the various effects on a biosphere of violent but rare astrophysical events such as supernovae and gamma-ray bursts. The influences of CR can also be duplicitous, such as limiting the survival of surface life on Mars while potentially supporting a subsurface biosphere in the ocean of Europa. This review highlights the common thread that ionizing radiation forms between the disparate component disciplines of astrobiology. PMID:21774684

  7. Remote radiation dosimetry

    DOEpatents

    Braunlich, Peter F. (Pullman, WA); Tetzlaff, Wolfgang (Pullman, WA); Hegland, Joel E. (Pullman, WA); Jones, Scott C. (Pullman, WA)

    1991-01-01

    Disclosed are methods and apparatus for remotely measuring radiation levels. Such are particularly useful for measuring relatively high levels or dosages of radiation being administered in radiation therapy. They are also useful for more general radiation level measurements where remote sensing from the remaining portions of the apparatus is desirable. The apparatus uses a beam generator, such as a laser beam, to provide a stimulating beam. The stimulating beam is preferably of wavelengths shorter than 6 microns, or more advantageously less than 2 microns. The stimulating beam is used to stimulate a remote luminescent sensor mounted in a probe which emits stored luminescent energy resulting from exposure of the sensor to ionizing radiation. The stimulating beam is communicated to the remote luminescent sensor via transmissive fiber which also preferably serves to return the emission from the luminescent sensor. The stimulating beam is advantageously split by a beam splitter to create a detector beam which is measured for power during a reading period during which the luminescent phosphor is read. The detected power is preferably used to control the beam generator to thus produce desired beam power during the reading period. The luminescent emission from the remote sensor is communicated to a suitable emission detector, preferably after filtering or other selective treatment to better isolate the luminescent emission.

  8. Remote radiation dosimetry

    DOEpatents

    Braunlich, P.F.; Tetzlaff, W.; Hegland, J.E.; Jones, S.C.

    1991-03-12

    Disclosed are methods and apparatus for remotely measuring radiation levels. Such are particularly useful for measuring relatively high levels or dosages of radiation being administered in radiation therapy. They are also useful for more general radiation level measurements where remote sensing from the remaining portions of the apparatus is desirable. The apparatus uses a beam generator, such as a laser beam, to provide a stimulating beam. The stimulating beam is preferably of wavelengths shorter than 6 microns, or more advantageously less than 2 microns. The stimulating beam is used to stimulate a remote luminescent sensor mounted in a probe which emits stored luminescent energy resulting from exposure of the sensor to ionizing radiation. The stimulating beam is communicated to the remote luminescent sensor via a transmissive fiber which also preferably serves to return the emission from the luminescent sensor. The stimulating beam is advantageously split by a beam splitter to create a detector beam which is measured for power during a reading period during which the luminescent phosphor is read. The detected power is preferably used to control the beam generator to thus produce desired beam power during the reading period. The luminescent emission from the remote sensor is communicated to a suitable emission detector, preferably after filtering or other selective treatment to better isolate the luminescent emission. 8 figures.

  9. Lunar radiator shade

    NASA Technical Reports Server (NTRS)

    Ewert, Michael K. (inventor)

    1992-01-01

    An apparatus for rejecting waste heat from a system located on or near the lunar equator is presented. The system utilizes a reflective catenary shaped trough deployed about a vertical radiator to shade the radiator from heat emitted by the hot lunar surface. The catenary shaped trough is constructed from a film material and is aligned relative to the sun so that incoming solar energy is focused to a line just above the vertical radiator and can thereby isolate the radiator from the effects of direct sunlight. The film is in a collapsed position between side by side support rods, all of which are in a transport case. To deploy the film and support rods, a set of parallel tracks running perpendicular to length of the support rods are extended out from the transport case. After the support tracks are deployed, the support rods are positioned equidistant from each other along the length of the support tracks so that the flexible film shade between adjacent support rods is unfolded and hangs in a catenary shaped trough. A heat radiator is supported between each pair of support rods above each hanging reflective trough.

  10. Synchrotron Radiation Workshop (SRW)

    Energy Science and Technology Software Center (ESTSC)

    2013-03-01

    "Synchrotron Radiation Workshop" (SRW) is a physical optics computer code for calculation of detailed characteristics of Synchrotron Radiation (SR) generated by relativistic electrons in magnetic fields of arbitrary configuration and for simulation of the radiation wavefront propagation through optical systems of beamlines. Frequency-domain near-field methods are used for the SR calculation, and the Fourier-optics based approach is generally used for the wavefront propagation simulation. The code enables both fully- and partially-coherent radiation propagation simulations inmore »steady-state and in frequency-/time-dependent regimes. With these features, the code has already proven its utility for a large number of applications in infrared, UV, soft and hard X-ray spectral range, in such important areas as analysis of spectral performances of new synchrotron radiation sources, optimization of user beamlines, development of new optical elements, source and beamline diagnostics, and even complete simulation of SR based experiments. Besides the SR applications, the code can be efficiently used for various simulations involving conventional lasers and other sources. SRW versions interfaced to Python and to IGOR Pro (WaveMetrics), as well as cross-platform library with C API, are available.« less

  11. Radiative Forcing by Contrails

    NASA Technical Reports Server (NTRS)

    Meerkoetter, R.; Schumann, U.; Doelling, D. R.; Nakajima, T.; Tsushima, Y.

    1999-01-01

    A parametric study of the instantaneous radiative impact of contrails is presented using three different radiative transfer models for a series of model atmospheres and cloud parameters. Contrails are treated as geometrically and optically thin plane parallel homogeneous cirrus layers in a static atmospheres The ice water content is varied as a function of ambient temperature. The model atmospheres include tropical, mid-latitude, and subarctic summer and winter atmospheres Optically thin contrails cause a positive net forcing at top of the atmosphere. At the surface the radiative forcing is negative during daytime. The forcing increases with the optical depth and the amount of contrail cover. At the top of the atmosphere a mean contrail cover of 0.1% with average optical depth of 0.2 to 0.5 causes about 0.01 to 0.03 W/m(exp 2)a daily mean instantaneous radiative forcing. Contrails cool the surface during the day and heat the surface during the night, and hence reduce the daily temperature amplitude The net effect depends strongly on the daily variation of contrail cloud cover. The indirect radiative forcing due to particle changes in natural cirrus clouds may be of the same magnitude as the direct one due to additional cover.

  12. Packet personal radiation monitor

    DOEpatents

    Phelps, J.E.

    1988-03-31

    A personal radiation monitor of the chirper type is provided for detecting ionizing radiation. A battery powered high voltage power supply is used to generate and apply a high voltage bias to a G-M tube radiation sensor. The high voltage is monitored by a low-loss sensing network which generates a feedback signal to control the high voltage power supply such that the high voltage bias is recharged to +500 VDC when the current pulses of the sensor, generated by the detection of ionizing radiatonevents, discharges the high voltage bias to +450 VDC. During the high voltage recharge period an audio transducer is activated to produce an audible ''chirp''. The rate of the ''chirps'' is controlled by the rate at which the high voltage bias is recharged, which is proportional to the radiation field intensity to which the sensor is exposed. The chirp rate sensitivity is set to be approximately 1.5 (chirps/min/MR/hr.). The G-M tube sensor is used in a current sensing mode so that the device does not paralyze in a high radiation field. 2 figs.

  13. Solar radiation on Mars: Stationary photovoltaic array

    NASA Technical Reports Server (NTRS)

    Appelbaum, J.; Sherman, I.; Landis, G. A.

    1993-01-01

    Solar energy is likely to be an important power source for surface-based operation on Mars. Photovoltaic cells offer many advantages. In this article we have presented analytical expressions and solar radiation data for stationary flat surfaces (horizontal and inclined) as a function of latitude, season and atmospheric dust load (optical depth). The diffuse component of the solar radiation on Mars can be significant, thus greatly affecting the optimal inclination angle of the photovoltaic surface.

  14. Solar radiation on Mars: Update 1990

    NASA Technical Reports Server (NTRS)

    Appelbaum, Joseph; Flood, Dennis J.

    1990-01-01

    Detailed information on solar radiation characteristics on Mars are necessary for effective design of future planned solar energy systems operating on the surface of Mars. The authors present a procedure and solar radiation related data from which the diurnally and daily variation of the global, direct beam and diffuse insolation on Mars are calculated. The radiation data are based on measured optical depth of the Martian atmosphere derived from images taken of the Sun with a special diode on the Viking Lander cameras and computation based on multiple wavelength and multiple scattering of the solar radiation. This work is an update to NASA-TM-102299 and includes a refinement of the solar radiation model.

  15. Ground truth data for test sites (SL-4). [thermal radiation brightness temperature and solar radiation measurments

    NASA Technical Reports Server (NTRS)

    1974-01-01

    Field measurements performed simultaneous with Skylab overpass in order to provide comparative calibration and performance evaluation measurements for the EREP sensors are presented. Wavelength region covered include: solar radiation (400 to 1300 nanometer), and thermal radiation (8 to 14 micrometer). Measurements consisted of general conditions and near surface meteorology, atmospheric temperature and humidity vs altitude, the thermal brightness temperature, total and diffuse solar radiation, direct solar radiation (subsequently analyzed for optical depth/transmittance), and target reflectivity/radiance. The particular instruments used are discussed along with analyses performed. Detailed instrument operation, calibrations, techniques, and errors are given.

  16. Audible radiation monitor

    SciTech Connect

    Odell, D.M.C.

    1992-12-31

    This invention consists of a method and apparatus for monitoring ionizing radiation comprising radiation detectors in electrical connection with an isotopic analyzer and a device for producing chords to which each isotope is mapped so that the device produces a unique chord for each isotope. Preferably the chords are pleasing to the ear, except for chords representing unexpected isotopes, and are louder or softer depending on the level of radioactivity produced by each isotope, and musical instrument voices may be simulated in producing the chords as an aid to distinguishing similar-sounding chords. Because of the representation by chords, information regarding the level and composition of the radiation in an area can be conveyed to workers in that area more effectively and yet without distracting them.

  17. Computing radiation exchange

    NASA Astrophysics Data System (ADS)

    Nutzati Fontaine, Jonathan L.

    A computational tool to simulate thermal radiation between surfaces is developed. The output is verified against cases for which the analytical solutions are available. The tool can be used as a stand-alone program, or as an interactive module for CFD. In such an application the module would augment other heat transfer boundary conditions. The tool is demonstrated by post-processing surface temperature field data from a supersonic CFD calculation. The result is a net thermal radiation surface data field - the black body radiative effluxes as functions of temperature, less the integrated influxes multiplied by their geometric view factors from other surface cells. An algorithm to compute blocking, or "shadowing" of surfaces is presented and demonstrated on a simple geometry. Validations using a geometrically complex experimental case from the literature is performed.

  18. Uses of synchrotron radiation

    SciTech Connect

    Gordon, B.M.

    1982-01-01

    X-ray fluorescence has long been used as a technique for elemental analysis. X-ray fluorescence techniques have a number of features that make them attractive for application to biomedical samples. In the past few years synchrotron radiation x-ray sources have been developed and, because of their properties, their use can improve the sensitivity for trace element analysis by two to three orders of magnitude. Also, synchrotron radiation will make possible an x-ray microprobe with resolution in the micrometer range. The National Synchrotron Light Source (NSLS), a dedicated synchrotron radiation source recently built at Brookhaven National Laboratory, will have a facility for trace element analysis by x-ray fluorescence and will be available to all interested users.

  19. Composition for radiation shielding

    DOEpatents

    Kronberg, J.W.

    1994-08-02

    A composition for use as a radiation shield is disclosed. The shield has a depleted uranium core for absorbing gamma rays and a bismuth coating for preventing chemical corrosion and absorbing gamma rays. Alternatively, a sheet of gadolinium may be positioned between the uranium core and the bismuth coating for absorbing neutrons. The composition is preferably in the form of a container for storing materials that emit radiation such as gamma rays and neutrons. The container is preferably formed by casting bismuth around a pre-formed uranium container having a gadolinium sheeting, and allowing the bismuth to cool. The resulting container is a structurally sound, corrosion-resistant, radiation-absorbing container. 2 figs.

  20. New radiative shocks experiment

    NASA Astrophysics Data System (ADS)

    Leygnac, S.; Bouquet, S.; Stehlé, C.; Benuzzi, A.; Boireau, J.-P.; Chièze, J.-P.; Grandjouan, N.; Huser, G.; Koenig, M.; Malka, V.; Merdji, H.; Michaut, C.; Thais, F.; Vinci, T.

    2002-06-01

    An experimental study of shocks with astrophysical relevance is performed with the high energy density laser of the LULI, at the Ecole Polytechnique. The peculiarity of these shocks is the strong coupling between radiation and hydrodynamics which leads to a structure governed by a radiative precursor. A new experiment has been performed this year where we have observed shocks identified as radiative shocks. We study them in various experimental configurations (several speeds and geometries of the medium where the shock propagates, allowing a quasi-planar or a quasi-spherical expansion). From the measurements it is possible to infer several features of the shock such as the speed, the electronic density, the geometrical shape and spectroscopic informations. The results will be studied with numerical simulations.

  1. Audible radiation monitor

    DOEpatents

    Odell, Daniel M. C. (11 Russellwood Ct., Aiken, SC 29803)

    1993-01-01

    A method and apparatus for monitoring ionizing radiation comprising radiation detectors in electrical connection with an isotopic analyzer and a device for producing chords to which each isotope is mapped so that the device produces a unique chord for each isotope. Preferably the chords are pleasing to the ear, except for chords representing unexpected isotopes, and are louder or softer depending on the level of radioactivity produced by each isotope, and musical instrument voices may be simulated in producing the chords as an aid to distinguishing similar-sounding chords. Because of the representation by chords, information regarding the level and composition of the radiation in an area can be conveyed to workers in that area more effectively and yet without distracting them.

  2. LDEF Satellite Radiation Analyses

    NASA Technical Reports Server (NTRS)

    Armstrong, T. W.; Colborn, B. L.

    1996-01-01

    This report covers work performed by Science Applications International Corporation (SAIC) under contract NAS8-39386 from the NASA Marshall Space Flight Center entitled LDEF Satellite Radiation Analyses. The basic objective of the study was to evaluate the accuracy of present models and computational methods for defining the ionizing radiation environment for spacecraft in Low Earth Orbit (LEO) by making comparisons with radiation measurements made on the Long Duration Exposure Facility (LDEF) satellite, which was recovered after almost six years in space. The emphasis of the work here is on predictions and comparisons with LDEF measurements of induced radioactivity and Linear Energy Transfer (LET) measurements. These model/data comparisons have been used to evaluate the accuracy of current models for predicting the flux and directionality of trapped protons for LEO missions.

  3. Solar cell radiation handbook

    NASA Technical Reports Server (NTRS)

    Tada, H. Y.; Carter, J. R., Jr.; Anspaugh, B. E.; Downing, R. G.

    1982-01-01

    The handbook to predict the degradation of solar cell electrical performance in any given space radiation environment is presented. Solar cell theory, cell manufacturing and how they are modeled mathematically are described. The interaction of energetic charged particles radiation with solar cells is discussed and the concept of 1 MeV equivalent electron fluence is introduced. The space radiation environment is described and methods of calculating equivalent fluences for the space environment are developed. A computer program was written to perform the equivalent fluence calculations and a FORTRAN listing of the program is included. Data detailing the degradation of solar cell electrical parameters as a function of 1 MeV electron fluence are presented.

  4. Pediatric radiation oncology

    SciTech Connect

    Halperin, E.C.; Kun, L.E.; Constine, L.S.; Tarbell, N.J.

    1989-01-01

    This text covers all aspects of radiation therapy for treatment of pediatric cancer. The book describes the proper use of irradiation in each of the malignancies of childhood, including tumors that are rarely encountered in adult practice. These include acute leukemia; supratentorial brain tumors; tumors of the posterior fossa of the brain and spinal canal; retinoblastoma and optic nerve glioma; neuroblastoma; Hodgkin's disease; malignant lymphoma; Ewing's sarcoma; osteosarcoma; rhabdomyosarcoma; Desmoid tumor; Wilms' tumor; liver and biliary tumors; germ cell and stromal cell tumors of the gonads; endocrine, aerodigestive tract, and breast tumors; Langerhans' cell histiocytosis; and skin cancer and hemangiomas. For each type of malignancy, the authors describe the epidemiology, common presenting signs and symptoms, staging, and proper diagnostic workup. Particular attention is given to the indications for radiation therapy and the planning of a course of radiotherapy, including the optimal radiation dose, field size, and technique.

  5. Semiconductor radiation detector

    DOEpatents

    Bell, Zane W. (Oak Ridge, TN); Burger, Arnold (Knoxville, TN)

    2010-03-30

    A semiconductor detector for ionizing electromagnetic radiation, neutrons, and energetic charged particles. The detecting element is comprised of a compound having the composition I-III-VI.sub.2 or II-IV-V.sub.2 where the "I" component is from column 1A or 1B of the periodic table, the "II" component is from column 2B, the "III" component is from column 3A, the "IV" component is from column 4A, the "V" component is from column 5A, and the "VI" component is from column 6A. The detecting element detects ionizing radiation by generating a signal proportional to the energy deposited in the element, and detects neutrons by virtue of the ionizing radiation emitted by one or more of the constituent materials subsequent to capture. The detector may contain more than one neutron-sensitive component.

  6. String radiative backreaction

    SciTech Connect

    Battye, R.A.; Shellard, E.P.

    1995-12-01

    We discuss radiative backreaction for global strings described by the Kalb-Ramond action with an analogous derivation to that for the point electron in classical electrodynamics. We show how local corrections to the equations of motion allow one to separate the self-field of the string from that of the radiation field. Modifications to this {open_quote}{open_quote}local backreaction approximation{close_quote}{close_quote} circumvent the runaway solutions, allowing these corrections to be used to evolve string trajectories numerically. Comparisons are made with analytic and numerical radiation calculations from previous work and the merits and limitations of this approach are discussed. {copyright} {ital 1995 The American Physical Society.}

  7. Saturn Radiation (SATRAD) Model

    NASA Technical Reports Server (NTRS)

    Garrett, H. B.; Ratliff, J. M.; Evans, R. W.

    2005-01-01

    The Saturnian radiation belts have not received as much attention as the Jovian radiation belts because they are not nearly as intense-the famous Saturnian particle rings tend to deplete the belts near where their peak would occur. As a result, there has not been a systematic development of engineering models of the Saturnian radiation environment for mission design. A primary exception is that of Divine (1990). That study used published data from several charged particle experiments aboard the Pioneer 1 1, Voyager 1, and Voyager 2 spacecraft during their flybys at Saturn to generate numerical models for the electron and proton radiation belts between 2.3 and 13 Saturn radii. The Divine Saturn radiation model described the electron distributions at energies between 0.04 and 10 MeV and the proton distributions at energies between 0.14 and 80 MeV. The model was intended to predict particle intensity, flux, and fluence for the Cassini orbiter. Divine carried out hand calculations using the model but never formally developed a computer program that could be used for general mission analyses. This report seeks to fill that void by formally developing a FORTRAN version of the model that can be used as a computer design tool for missions to Saturn that require estimates of the radiation environment around the planet. The results of that effort and the program listings are presented here along with comparisons with the original estimates carried out by Divine. In addition, Pioneer and Voyager data were scanned in from the original references and compared with the FORTRAN model s predictions. The results were statistically analyzed in a manner consistent with Divine s approach to provide estimates of the ability of the model to reproduce the original data. Results of a formal review of the model by a panel of experts are also presented. Their recommendations for further tests, analyses, and extensions to the model are discussed.

  8. Radiation in Particle Simulations

    SciTech Connect

    More, R M; Graziani, F R; Glosli, J; Surh, M

    2009-06-15

    Hot dense radiative (HDR) plasmas common to Inertial Confinement Fusion (ICF) and stellar interiors have high temperature (a few hundred eV to tens of keV), high density (tens to hundreds of g/cc) and high pressure (hundreds of Megabars to thousands of Gigabars). Typically, such plasmas undergo collisional, radiative, atomic and possibly thermonuclear processes. In order to describe HDR plasmas, computational physicists in ICF and astrophysics use atomic-scale microphysical models implemented in various simulation codes. Experimental validation of the models used to describe HDR plasmas are difficult to perform. Direct Numerical Simulation (DNS) of the many-body interactions of plasmas is a promising approach to model validation but, previous work either relies on the collisionless approximation or ignores radiation. We present four methods that attempt a new numerical simulation technique to address a currently unsolved problem: the extension of molecular dynamics to collisional plasmas including emission and absorption of radiation. The first method applies the Lienard-Weichert solution of Maxwell's equations for a classical particle whose motion is assumed to be known (section 3). The second method expands the electromagnetic field in normal modes (plane-waves in a box with periodic boundary-conditions) and solves the equation for wave amplitudes coupled to the particle motion (section 4). The third method is a hybrid MD/MC (molecular dynamics/Monte Carlo) method which calculates radiation emitted or absorbed by electron-ion pairs during close collisions (section 5). The fourth method is a generalization of the third method to include small clusters of particles emitting radiation during close encounters: one electron simultaneously hitting two ions, two electrons simultaneously hitting one ion, etc.(section 6). This approach is inspired by the Virial expansion method of equilibrium statistical mechanics.

  9. Small Active Radiation Monitor

    NASA Technical Reports Server (NTRS)

    Badhwar, Gautam D.

    2004-01-01

    A device, named small active radiation monitor, allows on-orbit evaluations during periods of increased radiation, after extravehicular activities, or at predesignated times for crews on such long-duration space missions as on the International Space Station. It also permits direct evaluation of biological doses, a task now performed using a combination of measurements and potentially inaccurate simulations. Indeed the new monitor can measure a full array of radiation levels, from soft x-rays to hard galactic cosmic-ray particles. With refinement, it will benefit commercial (nuclear power-plant workers, airline pilots, medical technicians, physicians/dentists, and others) and military personnel as well as the astronauts for whom thermoluminescent dosimeters are inadequate. Civilian and military personnel have long since graduated from film badges to thermoluminescent dosimeters. Once used, most dosimeters must be returned to a central facility for processing, a step that can take days or even weeks. While this suffices for radiation workers for whom exposure levels are typically very low and of brief duration, it does not work for astronauts. Even in emergencies and using express mail, the results can often be delayed by as much as 24 hours. Electronic dosimeters, which are the size of electronic oral thermometers, and tattlers, small electronic dosimeters that sound an alarm when the dose/dose rate exceeds preset values, are also used but suffer disadvantages similar to those of thermoluminescent dosimeters. None of these devices fully answers the need of rapid monitoring during the space missions. Instead, radiation is monitored by passive detectors, which are read out after the missions. Unfortunately, these detectors measure only the absorbed dose and not the biologically relevant dose equivalent. The new monitor provides a real-time readout, a time history of radiation exposures (both absorbed dose and biologically relevant dose equivalent), and a count of the number of particles passing through a unit area. Better still, the monitor can be used anywhere.

  10. Radiative Magnetic Reconnection in Astrophysics

    E-print Network

    Uzdensky, Dmitri A

    2015-01-01

    I review a new rapidly growing area of high-energy plasma astrophysics --- radiative magnetic reconnection, i.e., a reconnection regime where radiation reaction influences reconnection dynamics, energetics, and nonthermal particle acceleration. This influence be may be manifested via a number of astrophysically important radiative effects, such as radiation-reaction limits on particle acceleration, radiative cooling, radiative resistivity, braking of reconnection outflows by radiation drag, radiation pressure, viscosity, and even pair creation at highest energy densities. Self-consistent inclusion of these effects in magnetic reconnection theory and modeling calls for serious modifications to our overall theoretical approach to the problem. In addition, prompt reconnection-powered radiation often represents our only observational diagnostic tool for studying remote astrophysical systems; this underscores the importance of developing predictive modeling capabilities to connect the underlying physical condition...

  11. Radiation Monitoring Equipment Dosimeter Experiment

    NASA Technical Reports Server (NTRS)

    Hardy, Kenneth A.; Golightly, Michael J.; Quam, William

    1992-01-01

    Spacecraft crews risk exposure to relatively high levels of ionizing radiation. This radiation may come from charged particles trapped in the Earth's magnetic fields, charged particles released by solar flare activity, galactic cosmic radiation, energetic photons and neutrons generated by interaction of these primary radiations with spacecraft and crew, and man-made sources (e.g., nuclear power generators). As missions are directed to higher radiation level orbits, viz., higher altitudes and inclinations, longer durations, and increased flight frequency, radiation exposure could well become a major factor for crew stay time and career lengths. To more accurately define the radiological exposure and risk to the crew, real-time radiation monitoring instrumentation, which is capable of identifying and measuring the various radiation components, must be flown. This presentation describes a radiation dosimeter instrument which was successfully flown on the Space Shuttle, the RME-3.

  12. Radiation-induced hydrogen transfer in metals

    NASA Astrophysics Data System (ADS)

    Tyurin, Yu I.; Vlasov, V. A.; Dolgov, A. S.

    2015-11-01

    The paper presents processes of hydrogen (deuterium) diffusion and release from hydrogen-saturated condensed matters in atomic, molecular and ionized states under the influence of the electron beam and X-ray radiation in the pre-threshold region. The dependence is described between the hydrogen isotope release intensity and the current density and the electron beam energy affecting sample, hydrogen concentration in the material volume and time of radiation exposure to the sample. The energy distribution of the emitted positive ions of hydrogen isotopes is investigated herein. Mechanisms of radiation-induced hydrogen transfer in condensed matters are suggested.

  13. Radiation Detectors and Art

    NASA Astrophysics Data System (ADS)

    Denker, Andrea

    The use of radiation detectors in the analysis of art objects represents a very special application in a true interdisciplinary field. Radiation detectors employed in this field detect, e.g., x-rays, ?-rays, ? particles, and protons. Analyzed materials range from stones, metals, over porcelain to paintings. The available nondestructive and noninvasive analytical methods cover a broad range of techniques. Hence, for the sake of brevity, this chapter will concentrate on few techniques: Proton Induced X-ray Emission (PIXE) and Proton Induced ?-ray Emission (PIGE).

  14. Thermal radiative properties: Coatings.

    NASA Technical Reports Server (NTRS)

    Touloukian, Y. S.; Dewitt, D. P.; Hernicz, R. S.

    1972-01-01

    This volume consists, for the most part, of a presentation of numerical data compiled over the years in a most comprehensive manner on coatings for all applications, in particular, thermal control. After a moderately detailed discussion of the theoretical nature of the thermal radiative properties of coatings, together with an overview of predictive procedures and recognized experimental techniques, extensive numerical data on the thermal radiative properties of pigmented, contact, and conversion coatings are presented. These data cover metallic and nonmetallic pigmented coatings, enamels, metallic and nonmetallic contact coatings, antireflection coatings, resin coatings, metallic black coatings, and anodized and oxidized conversion coatings.

  15. Wireless passive radiation sensor

    DOEpatents

    Pfeifer, Kent B; Rumpf, Arthur N; Yelton, William G; Limmer, Steven J

    2013-12-03

    A novel measurement technique is employed using surface acoustic wave (SAW) devices, passive RF, and radiation-sensitive films to provide a wireless passive radiation sensor that requires no batteries, outside wiring, or regular maintenance. The sensor is small (<1 cm.sup.2), physically robust, and will operate unattended for decades. In addition, the sensor can be insensitive to measurement position and read distance due to a novel self-referencing technique eliminating the need to measure absolute responses that are dependent on RF transmitter location and power.

  16. Tunable terahertz radiation source

    DOEpatents

    Boulaevskii, Lev; Feldmann, David M; Jia, Quanxi; Koshelev, Alexei; Moody, Nathan A

    2014-01-21

    Terahertz radiation source and method of producing terahertz radiation, said source comprising a junction stack, said junction stack comprising a crystalline material comprising a plurality of self-synchronized intrinsic Josephson junctions; an electrically conductive material in contact with two opposing sides of said crystalline material; and a substrate layer disposed upon at least a portion of both the crystalline material and the electrically-conductive material, wherein the crystalline material has a c-axis which is parallel to the substrate layer, and wherein the source emits at least 1 mW of power.

  17. LDEF Satellite Radiation Analyses

    NASA Technical Reports Server (NTRS)

    Armstrong, T. W.; Colborn, B. L.

    1996-01-01

    Model calculations and analyses have been carried out to compare with several sets of data (dose, induced radioactivity in various experiment samples and spacecraft components, fission foil measurements, and LET spectra) from passive radiation dosimetry on the Long Duration Exposure Facility (LDEF) satellite, which was recovered after almost six years in space. The calculations and data comparisons are used to estimate the accuracy of current models and methods for predicting the ionizing radiation environment in low earth orbit. The emphasis is on checking the accuracy of trapped proton flux and anisotropy models.

  18. Solar cell radiation handbook

    NASA Technical Reports Server (NTRS)

    Tada, H. Y.; Carter, J. R., Jr.

    1977-01-01

    Solar cell theory cells are manufactured, and how they are modeled mathematically is reviewed. The interaction of energetic charged particle radiation with solar cells is discussed in detail and the concept of 1 MeV equivalent electron fluence is introduced. The space radiation environment is described and methods of calculating equivalent fluences for the space environment are developed. A computer program was written to perform the equivalent fluence calculations and a FORTRAN listing of the program is included. Finally, an extensive body of data detailing the degradation of solar cell electrical parameters as a function of 1 MeV electron fluence is presented.

  19. Radiation monitor for liquids

    DOEpatents

    Koster, J.E.; Bolton, R.D.

    1999-03-02

    A radiation monitor for use with liquids that utilizes air ions created by alpha radiation emitted by the liquids as its detectable element. A signal plane, held at an electrical potential with respect to ground, collects these air ions. A guard plane or guard rings is used to limit leakage currents. In one embodiment, the monitor is used for monitoring liquids retained in a tank. Other embodiments monitor liquids flowing through a tank, and bodies of liquids, such as ponds, lakes, rivers and oceans. 4 figs.

  20. Space Radiation and the Brain

    NASA Astrophysics Data System (ADS)

    Hampson, R. E.

    Solar and cosmic radiation pose a number of physiological challenges to human spaceflight outside the protective region of Earth's magnetosphere. Aside from well-described effects of radiation on the blood-forming tissues of the hematopoietic system, there is increasing evidence of direct effects of radiation on the brain as evidenced by studies showing longitudinal decline in memory and cognitive function following radiation specifically directed at brain tissue. These indications strengthen the need to more fully research effects of radiation - particular those components associated with solar wind and galactic cosmic radiation - on the nervous system of mammals from rodents to humans.

  1. Unruh radiation and Interference effect

    E-print Network

    Satoshi Iso; Yasuhiro Yamamoto; Sen Zhang

    2011-02-23

    A uniformly accelerated charged particle feels the vacuum as thermally excited and fluctuates around the classical trajectory. Then we may expect additional radiation besides the Larmor radiation. It is called Unruh radiation. In this report, we review the calculation of the Unruh radiation with an emphasis on the interference effect between the vacuum fluctuation and the radiation from the fluctuating motion. Our calculation is based on a stochastic treatment of the particle under a uniform acceleration. The basics of the stochastic equation are reviewed in another report in the same proceeding. In this report, we mainly discuss the radiation and the interference effect.

  2. http://emergency.cdc.gov/radiation RADIATION EMERGENCIES

    E-print Network

    's abdomen is exposed to radiation. Health effects to the fetus from radiation exposure can be severe, even to the fetus is lower than the dose to the woman. A pregnant woman's abdomen partially protects the fetus from

  3. Verification of the Radiation Package in ALEGRA

    SciTech Connect

    Budge, K.G.

    1999-04-01

    The ALEGRA radiation transport package implements diffusion, flux-limited diffusion, and SPn radiation transport for both gray and multigroup photon spectra. Comparisons of ALEGRA calculations with known solutions for a selection of benchmark problems for these transport theories are presented. ALEGRA returns accurate solutions in each case. This verifies that each transport theory has been implemented correctly, though it does not prove that the transport theories are valid for problems of interest at Sandia. A validation study will be presented in a future report.

  4. Management of ionizing radiation injuries and illnesses, part 1: physics, radiation protection, and radiation instrumentation.

    PubMed

    Christensen, Doran M; Jenkins, Mark S; Sugarman, Stephen L; Glassman, Erik S

    2014-03-01

    Ionizing radiation injuries and illnesses are exceedingly rare; therefore, most physicians have never managed such conditions. When confronted with a possible radiation injury or illness, most physicians must seek specialty consultation. Protection of responders, health care workers, and patients is an absolute priority for the delivery of medical care. Management of ionizing radiation injuries and illnesses, as well as radiation protection, requires a basic understanding of physics. Also, to provide a greater measure of safety when working with radioactive materials, instrumentation for detection and identification of radiation is needed. Because any health care professional could face a radiation emergency, it is imperative that all institutions have emergency response plans in place before an incident occurs. The present article is an introduction to basic physics, ionizing radiation, radiation protection, and radiation instrumentation, and it provides a basis for management of the consequences of a radiologic or nuclear incident. PMID:24567272

  5. ATMOSPHERIC RADIATION MEASUREMENT PROGRAM

    EPA Science Inventory

    The Atmospheric Radiation Measurement Program (ARM) is the largest global change research program supported by the U.S. Department of Energy (DOE). ARM scientists focus on obtaining field measurements and developing models to better understand the processes that control solar and...

  6. Radiation Hardening of Computers

    NASA Technical Reports Server (NTRS)

    Nichols, D. K.; Smith, L. S.; Zoutendyk, J. A.; Giddings, A. E.; Hewlett, F. W.; Treece, R. K.

    1986-01-01

    Single-event upsets reduced by use of oversize transistors. Computers made less susceptible to ionizing radiation by replacing bipolar integrated circuits with properly designed, complementary metaloxide-semiconductor (CMOS) circuits. CMOS circuit chips made highly resistant to single-event upset (SEU), especially when certain feedback resistors are incorporated. Redesigned chips also consume less power than original chips.

  7. Psoriasis and ultraviolet radiation

    SciTech Connect

    Farber, E.M.; Nall, L. )

    1993-09-01

    Prevention and detection screening programs as a public health service in curtailing the ever-increasing incidence of all forms of skin cancer are reviewed. The effect of solar and artificial ultraviolet radiation on the general population and persons with psoriasis is examined. 54 refs.

  8. Radiation Exposure and Pregnancy

    MedlinePLUS

    ... a medical procedure involving radiation increase my baby’s health risks?” What are the health risks from as well. If you are a candidate ... x ray or a radionu- mine the potential health risks. This information should clide medical test, consult your ...

  9. CCTV for radiation environments

    SciTech Connect

    Shaufl, R.A.

    1985-01-01

    The use of closed circuit television (CCTV) within radiation environments requires the system designer to have a thorough knowledge of the application environment and the electronic and optical components expected to survive within the environment. Of all the many ambient conditions to which CCTV components are exposed, from an air-conditioned office complex to 1,000 feet under the ocean, none is as demanding as the radiation encountered in the nuclear industrial field. Unhardened CCTV equipment can fail or degrade to the point of being useless when exposed to ionizing radiation doses of as little as 10/sup 3/ rads (Si) or to a neutron fluence of as little as 10/sup 11/ neutrons per square centimeter. (Rads (Si) stands for roentgens absorbed dose in silicon, while a fluence is defined as the time integral of neutron flux.) The applications for CCTV systems may require that each component within the system withstand a total ionizing radiation dose of 10/sup 8/ rads or greater.

  10. Thermodynamics of Radiation Modes

    ERIC Educational Resources Information Center

    Pina, Eduardo; de la Selva, Sara Maria Teresa

    2010-01-01

    We study the equilibrium thermodynamics of the electromagnetic radiation in a cavity of a given volume and temperature. We found three levels of description, the thermodynamics of one mode, the thermodynamics of the distribution of frequencies in a band by summing over the frequencies in it and the global thermodynamics by summing over all the…

  11. Radiation Source Replacement Workshop

    SciTech Connect

    Griffin, Jeffrey W.; Moran, Traci L.; Bond, Leonard J.

    2010-12-01

    This report summarizes a Radiation Source Replacement Workshop in Houston Texas on October 27-28, 2010, which provided a forum for industry and researchers to exchange information and to discuss the issues relating to replacement of AmBe, and potentially other isotope sources used in well logging.

  12. Continuum radiation at Uranus

    SciTech Connect

    Kurth, W.S.; Gurnett, D.A. ); Desch, M.D. )

    1990-02-01

    Uranus has proven to be a radio source of remarkable complexity with as many as six distinctly different types of emission. One Uranian radio emission which has thus far escaped attention is an analog of continuum radiation at Earth, Jupiter, and Saturn. The emission is found to be propagating in the ordinary mode in the range of one to a few kHz on the inbound leg of the Voyager 2 encounter, shortly after the magnetopause crossing. The continuum radiation spectrum at Uranus also includes bands with frequencies as high as 12 kHz or greater on both the inbound and outbound legs. The Uranian continuum radiation is notably weak, making it more like that detected at Saturn than the extremely intense Jovian continuum radiation. The Uranian emission shows some evidence for narrow-band components lying in the same frequency regime as the continuum, completing the analogy with the other planets, which also show narrow-band components superimposed on the continuum spectrum. The authors argue that the low intensity of the Uranian continuum is most likely related to the lack of a density cavity within the Uranian magnetosphere that is deep relative to the solar wind plasma density.

  13. Thermal radiation Ron Zevenhoven

    E-print Network

    Zevenhoven, Ron

    temperature separated by a transparent ("diathermal") medium, by electromagnetic waves Radiant energy can) region) A complicating factor is that radiant energy and also radiant properties of materials, 20500 Turku 7/64 Bandwidths: blackbody radiation functions Radiant energy emitted by a blackbody per

  14. Radiations from hot nuclei

    NASA Technical Reports Server (NTRS)

    Malik, F. Bary

    1993-01-01

    The investigation indicates that nuclei with excitation energy of a few hundred MeV to BeV are more likely to radiate hot nuclear clusters than neutrons. These daughter clusters could, furthermore, de-excite emitting other hot nuclei, and the chain continues until these nuclei cool off sufficiently to evaporate primarily neutrons. A few GeV excited nuclei could radiate elementary particles preferentially over neutrons. Impact of space radiation with materials (for example, spacecraft) produces highly excited nuclei which cool down emitting electromagnetic and particle radiations. At a few MeV excitation energy, neutron emission becomes more dominant than gamma-ray emission and one often attributes the cooling to take place by successive neutron decay. However, a recent experiment studying the cooling process of 396 MeV excited Hg-190 casts some doubt on this thinking, and the purpose of this investigation is to explore the possibility of other types of nuclear emission which might out-compete with neutron evaporation.

  15. VDT Emissions Radiate Debate.

    ERIC Educational Resources Information Center

    Morgan, Bill

    1990-01-01

    Discusses the possible health effects of electromagnetic fields of radiation that are emitted from video display terminals (VDTs). Responses from vendors in the computer industry are related, steps to reduce possible risks are suggested, and additional sources of information on VDTs are listed. (LRW)

  16. Thermostatic Radiator Valve Evaluation

    SciTech Connect

    Dentz, Jordan; Ansanelli, Eric

    2015-01-01

    A large stock of multifamily buildings in the Northeast and Midwest are heated by steam distribution systems. Losses from these systems are typically high and a significant number of apartments are overheated much of the time. Thermostatically controlled radiator valves (TRVs) are one potential strategy to combat this problem, but have not been widely accepted by the residential retrofit market.

  17. Radiation detector spectrum simulator

    DOEpatents

    Wolf, M.A.; Crowell, J.M.

    1985-04-09

    A small battery operated nuclear spectrum simulator having a noise source generates pulses with a Gaussian distribution of amplitudes. A switched dc bias circuit cooperating therewith to generate several nominal amplitudes of such pulses and a spectral distribution of pulses that closely simulates the spectrum produced by a radiation source such as Americium 241.

  18. Paradoxes of Thermal Radiation

    ERIC Educational Resources Information Center

    Besson, U.

    2009-01-01

    This paper presents an analysis of the thermal behaviour of objects exposed to a solar-type flux of thermal radiation. It aims to clarify certain apparent inconsistencies between theory and observation, and to give a detailed exposition of some critical points that physics textbooks usually treat in an insufficient or incorrect way. In particular,…

  19. Nuclear Radiation Damages Minds!

    ERIC Educational Resources Information Center

    Blai, Boris, Jr.

    Professors Ernest Sternglass (University of Pittsburgh) and Steven Bell (Berry College) have assembled cogent, conclusive evidence indicating that nuclear radiation is associated with impaired cognition. They suggest that Scholastic Aptitude Scores (SATs), which have declined steadily for 19 years, will begin to rise. Their prediction is based on…

  20. An Inexpensive Radiation Counter.

    ERIC Educational Resources Information Center

    Holton, Brian; Balla, Zsolt

    1985-01-01

    Describes a radiation counter comparable to commercial units which costs less than $100. It consists of six sections: Geiger-Mueller tube and holder; high voltage supply; low voltage supply; pulse shaping circuit; "start/stop counts" gating circuit; and counter/display. List of materials needed and schematic diagrams are included. (JN)

  1. Radiation detector spectrum simulator

    DOEpatents

    Wolf, Michael A. (Los Alamos, NM); Crowell, John M. (Los Alamos, NM)

    1987-01-01

    A small battery operated nuclear spectrum simulator having a noise source nerates pulses with a Gaussian distribution of amplitudes. A switched dc bias circuit cooperating therewith generates several nominal amplitudes of such pulses and a spectral distribution of pulses that closely simulates the spectrum produced by a radiation source such as Americium 241.

  2. Photovoltaic radiation detector element

    DOEpatents

    Agouridis, D.C.

    1980-12-17

    A radiation detector element is formed of a body of semiconductor material, a coating on the body which forms a photovoltaic junction therewith, and a current collector consisting of narrow metallic strips, the aforesaid coating having an opening therein in the edge of which closely approaches but is spaced from the current collector strips.

  3. Involved Field Radiation After Autologous Stem Cell Transplant for Diffuse Large B-Cell Lymphoma in the Rituximab Era

    SciTech Connect

    Biswas, Tithi; Dhakal, Sughosh; Chen Rui; Hyrien, Ollivier; Bernstein, Steven; Friedberg, Jonathan W.; Fisher, Richard I.; Liesveld, Jane; Phillips, Gordon; Constine, Louis S.

    2010-05-01

    Purpose: For patients with recurrent or refractory large B-cell non-Hodgkin's lymphoma, high-dose chemotherapy and autologous stem cell transplant (ASCT) is the treatment of choice. We evaluated the role of involved field radiation therapy (IFRT) post-ASCT for patients initially induced with cyclophosphamide, adriamycin, vincristine, and prednisone (CHOP) or, more recently, rituximab-CHOP (R-CHOP). Materials and Methods: Between May 1992 and April 2005, 176 patients underwent ASCT for recurrent or refractory large B-cell non-Hodgkin's lymphoma; 164 patients were evaluable for endpoint analysis. Fifty percent of the CHOP group (n = 131), and 39% of the R-CHOP group (n = 33), received IFRT. Follow-up from the time of transplant was a median/mean of 1.7/3 years (range, 0.03-13 years). Results: The 5-year overall survival (OS) and disease-specific survival (DSS) improved with IFRT in both the R-CHOP (p = 0.006 and 0.02, respectively) and CHOP (p = 0.02 and p = 0.04, respectively) groups. IFRT was associated with a 10% (p = 0.17) reduction in local failure, alone or with a distant site. On univariate analysis, IFRT was associated with superior OS (hazard ratio [HR] = 0.50 [95% CI 0.32, 0.78]; p = 0.002) and DSS (HR = 0.53 [95% CI 0.33, 0.86]; p = 0.009). Presence of B symptoms was adverse (p = 0.03). On multivariate analysis, only IFRT was associated with significant improvement in OS (HR = 0.35 [0.18, 0.68]; p = 0.002) and DSS (HR = 0.39 [95% CI 0.18, 0.84]; p = 0.01). Conclusions: Recognizing that positive and negative patient selection bias exists for the use of IFRT post-ASCT, patients initially treated with CHOP or R-CHOP and who undergo ASCT for recurrent or refractory disease may benefit from subsequent IFRT presumably due to enhanced local control that can translate into a survival advantage.

  4. Radiative accelerations in stellar envelopes

    NASA Astrophysics Data System (ADS)

    Seaton, M. J.

    1997-08-01

    In stars which are sufficiently quiescent, changes in the relative abundances of the chemical elements can result from gravitational settling and from levitation produced by radiation pressure forces, usually expressed as radiative accelerations g_rad. Those changes can affect the structure of such stars, due to modifications in opacities, and can lead to marked peculiarities in observed atmospheric abundances. It is necessary to consider diffusive movements both in the atmospheres and in much deeper layers of the stellar envelopes. For the envelopes the equation of radiative transfer can be solved in a diffusion approximation and, for an element k in ionization stage j, one obtains expressions for g_rad(j, k) proportional to the total radiative flux, to the Rosseland-mean opacity kappa_R (which may depend on the abundance of k), and to a dimensionless quantity gamma(j, k) which, due to saturation effects, can be sensitive to the abundance of k. The radiative accelerations are required for each ionization stage, because the diffusion coefficients depend on j. Using atomic data obtained in the course of the work of the Opacity Project (OP), we calculate kappa_R and gamma(j, k) for the chemical elements C, N, O, Ne, Na, Mg, Al, Si, S, Ar, Ca, Cr, Mn, Fe and Ni. We start from standard Solar system abundances, and then vary the abundance of one element at a time (element k) by a factor chi. The following results are obtained and are available at the Centre de Donnees astronomiques de Strasbourg (CDS). (1) Files stages.zz (where zz specifies the nuclear charge of the selected element k) containing values of kappa_R and gamma(j, k) on a mesh of values of (T, N_e, chi), where T is temperature, and N_e is electron density. We include derivatives of kappa_R and gamma(j, k) with respect to chi, which are used for making interpolations. (2) A code add.f which reads a file stages.zz and writes a file acc.zz containing values of gamma(k) obtained on summing the gamma(j, k), weighted by diffusion coefficients. The diffusion coefficients to be employed can be selected by the user. (3) A code acc.f which reads a file acc.zz and provides facilities for interpolations of kappa_R and g_rad(k) to values of (T, rho, chi) for a stellar model, where rho is mass density. The mesh to be used for log(chi) is specified by the user. (4) A code diff.f intended for use in diffusion calculations. It reads a file created by acc.f and provides function subroutines for the calculation of kappa_R and g_rad(k) for any specified depth-point and any value of chi. Results are compared with those from other recent work for C, N, O, Ca and Fe.

  5. Appendix F. Radiation Appendix F. Radiation F-3

    E-print Network

    Pennycook, Steve

    . The number of neutrons and protons determines the atomic weight. Atoms of the same element that have properties but different atomic weights (Fig. F.1). For example, the element uranium has 92 protons. All of radiation, including atoms and isotopes; types, sources, and pathways of radiation; radiation measurement

  6. RADIATION ELEMENT METHOD FOR TRANSIENT HYPERBOLIC RADIATIVE TRANSFER IN

    E-print Network

    Guo, Zhixiong "James"

    such as laser material processing of microstructures [4], optical tomography [5], laser therapy and ablation [6 transient radiative transfer with light radiation propagation effect in scattering, absorbing, and emitting is essential in short-pulse laser radiation transport when the input pulse width is not considerably larger

  7. Apparatus for generating partially coherent radiation

    DOEpatents

    Naulleau, Patrick P.

    2005-02-22

    Techniques for generating partially coherent radiation and particularly for converting effectively coherent radiation from a synchrotron to partially coherent EUV radiation suitable for projection lithography.

  8. Radiation risk and public education

    SciTech Connect

    Faden, R.R.

    1983-03-01

    Two issues which deal with the public's perception of radiation hazards are discussed. The goal of public education about radiation, and the relative role of scientific and moral beliefs in public education are examined. (KRM)

  9. Acceleration and Classical Electromagnetic Radiation

    E-print Network

    E. N. Glass

    2008-01-09

    Classical radiation from an accelerated charge is reviewed along with the reciprocal topic of accelerated observers detecting radiation from a static charge. This review commemerates Bahram Mashhoon's 60th birthday.

  10. Conical electromagnetic radiation flux concentrator

    NASA Technical Reports Server (NTRS)

    Miller, E. R.

    1972-01-01

    Concentrator provides method of concentrating a beam of electromagnetic radiation into a smaller beam, presenting a higher flux density. Smaller beam may be made larger by sending radiation through the device in the reverse direction.

  11. RADIATION ENVIRONMENT OF GROWTH CHAMBERS

    EPA Science Inventory

    Radiation measurements with different types of meters in several controlled environment facilities have been compiled to demonstrate the problems associated with insuring uniform radiation levels in separate facilities. Data are provided for a quantum meter, three photometers, a ...

  12. Radiation Shielding and Radiological Protection

    E-print Network

    Shultis, J. Kenneth

    of Mechanical and Nuclear Engineering, Kansas State University, Manhattan, KS, USA jks@ksu.edu fawre .................................. Basic Methods in Radiation Attenuation Calculations..................... . The Point-Kernel Concept.), Handbook of Nuclear Engineering, DOI ./----_, © Springer Science+Business Media LLC #12; Radiation

  13. DCTD — Radiation Research Program (RRP)

    Cancer.gov

    Of the many successful programs within the RRP grant and contract portfolio, several scientific advances are presented below, representing significant advances in treatment development, molecular radiation therapy, quality assurance for high-technology radiation therapy, and international networking.

  14. Radiation Risk From Medical Imaging

    PubMed Central

    Lin, Eugene C.

    2010-01-01

    This review provides a practical overview of the excess cancer risks related to radiation from medical imaging. Primary care physicians should have a basic understanding of these risks. Because of recent attention to this issue, patients are more likely to express concerns over radiation risk. In addition, physicians can play a role in reducing radiation risk to their patients by considering these risks when making imaging referrals. This review provides a brief overview of the evidence pertaining to low-level radiation and excess cancer risks and addresses the radiation doses and risks from common medical imaging studies. Specific subsets of patients may be at greater risk from radiation exposure, and radiation risk should be considered carefully in these patients. Recent technical innovations have contributed to lowering the radiation dose from computed tomography, and the referring physician should be aware of these innovations in making imaging referrals. PMID:21123642

  15. Name______ __________________________ Lab 5. Radioactivity & Radiation

    E-print Network

    Perfect, Ed

    1 Name______ __________________________ Lab 5. Radioactivity & Radiation Radiation pollution in general. On the other hand, radioactive waste is an inevitable byproduct of nuclear reactions, is lethal to all living organisms. Furthermore, radioactive waste can be extremely persistent, and can

  16. Simple device measures solar radiation

    NASA Technical Reports Server (NTRS)

    Humphries, W. R.

    1977-01-01

    Simple inexpensive thermometer, insolated from surroundings by transparent glass or plastic encasement, measures intensities of solar radiation, or radiation from other sources such as furnaces or ovens. Unit can be further modified to accomplish readings from remote locations.

  17. Radiation from Cardiac Imaging Tests

    MedlinePLUS

    ... User Name Password Sign In Cardiology Patient Page Radiation From Cardiac Imaging Tests Questions You Should Ask ... cardiac imaging techniques computed tomography imaging nuclear medicine radiation Next Section Introduction Many patients are referred by ...

  18. Health Effects of UV Radiation

    MedlinePLUS

    ... Google+ Pinterest Contact Us Health Effects of UV Radiation Fact Sheet Download the Health Effects of Overexposure ... natural protection from the sun’s harmful ultraviolet (UV) radiation. This Web page provides an overview of the ...

  19. Radiation Therapy for Skin Cancer

    MedlinePLUS

    LEARNING ABOUT CLINICAL TRIALS The radiation oncology treatment team is constantly exploring new ways to treat cancer through studies called clinical trials. Today’s standard radiation therapy treatments ...

  20. Resonance zones and quasi-linear diffusion coefficients for radiation belt energetic electron interaction with oblique chorus waves in the Dungey magnetosphere

    SciTech Connect

    Shi Run; Ni, Binbin; Gu Xudong; Zhao Zhengyu; Zhou Chen

    2012-07-15

    The resonance regions for resonant interactions of radiation belt electrons with obliquely propagating whistler-mode chorus waves are investigated in detail in the Dungey magnetic fields that are parameterized by the intensity of uniform southward interplanetary magnetic field (IMF) Bz or, equivalently, by the values of D=(M/B{sub z,0}){sup 1/3} (where M is the magnetic moment of the dipole and B{sub z,0} is the uniform southward IMF normal to the dipole's equatorial plane). Adoption of background magnetic field model can considerably modify the determination of resonance regions. Compared to the results for the case of D = 50 (very close to the dipole field), the latitudinal coverage of resonance regions for 200 keV electrons interacting with chorus waves tends to become narrower for smaller D-values, regardless of equatorial pitch angle, resonance harmonics, and wave normal angle. In contrast, resonance regions for 1 MeV electrons tend to have very similar spatial lengths along the field line for various Dungey magnetic field models but cover different magnetic field intervals, indicative of a strong dependence on electron energy. For any given magnetic field line, the resonance regions where chorus-electron resonant interactions can take place rely closely on equatorial pitch angle, resonance harmonics, and kinetic energy. The resonance regions tend to cover broader latitudinal ranges for smaller equatorial pitch angles, higher resonance harmonics, and lower electron energies, consistent with the results in Ni and Summers [Phys. Plasmas 17, 042902, 042903 (2010)]. Calculations of quasi-linear bounce-averaged diffusion coefficients for radiation belt electrons due to nightside chorus waves indicate that the resultant scattering rates differ from using different Dungey magnetic field models, demonstrating a strong dependence of wave-induced electron scattering effect on the adoption of magnetic field model. Our results suggest that resonant wave-particle interaction processes should be implemented into a sophisticated, accurate global magnetic field model to pursue comprehensive and complete models of radiation belt electron dynamics.

  1. Gamma radiation field intensity meter

    DOEpatents

    Thacker, L.H.

    1995-10-17

    A gamma radiation intensity meter measures dose rate of a radiation field. The gamma radiation intensity meter includes a tritium battery emitting beta rays generating a current which is essentially constant. Dose rate is correlated to an amount of movement of an electroscope element charged by the tritium battery. Ionizing radiation decreases the voltage at the element and causes movement. A bleed resistor is coupled between the electroscope support element or electrode and the ionization chamber wall electrode. 4 figs.

  2. Gamma radiation field intensity meter

    DOEpatents

    Thacker, Louis H. (Knoxville, TN)

    1995-01-01

    A gamma radiation intensity meter measures dose rate of a radiation field. The gamma radiation intensity meter includes a tritium battery emitting beta rays generating a current which is essentially constant. Dose rate is correlated to an amount of movement of an electroscope element charged by the tritium battery. Ionizing radiation decreases the voltage at the element and causes movement. A bleed resistor is coupled between the electroscope support element or electrode and the ionization chamber wall electrode.

  3. Gamma radiation field intensity meter

    DOEpatents

    Thacker, L.H.

    1994-08-16

    A gamma radiation intensity meter measures dose rate of a radiation field. The gamma radiation intensity meter includes a tritium battery emitting beta rays generating a current which is essentially constant. Dose rate is correlated to an amount of movement of an electroscope element charged by the tritium battery. Ionizing radiation decreases the voltage at the element and causes movement. A bleed resistor is coupled between the electroscope support element or electrode and the ionization chamber wall electrode. 4 figs.

  4. Gamma radiation field intensity meter

    DOEpatents

    Thacker, Louis H. (Knoxville, TN)

    1994-01-01

    A gamma radiation intensity meter measures dose rate of a radiation field. The gamma radiation intensity meter includes a tritium battery emitting beta rays generating a current which is essentially constant. Dose rate is correlated to an amount of movement of an electroscope element charged by the tritium battery. Ionizing radiation decreases the voltage at the element and causes movement. A bleed resistor is coupled between the electroscope support element or electrode and the ionization chamber wall electrode.

  5. Stromal Mediation of Radiation Carcinogenesis

    PubMed Central

    2011-01-01

    Ionizing radiation is a well-established carcinogen in human breast and rodent mammary gland. This review addresses evidence that radiation elicits the critical stromal context for cancer, affecting not only frequency but the type of cancer. Recent data from the breast tumors of women treated with radiation therapy and the cellular mechanisms evident in experimental models suggest that radiation effects on stromal-epithelial interactions and tissue composition are a major determinant of cancer development. PMID:21181431

  6. Spectroscopy Interaction of electromagnetic radiation

    E-print Network

    Gerwert, Klaus

    Spectroscopy 691 Interaction of electromagnetic radiation with atoms or molecules #12;Bacteriorhodopsin: a light-driven proton pump 486 #12;Electromagnetic Radiation 692 harmonic wave (Maxwell): y;Spectroscopy 691 Interaction of electromagnetic radiation with atoms or molecules two processes: emission

  7. Radiation Therapy Technology Professional Curriculum

    E-print Network

    Berdichevsky, Victor

    Radiation Therapy Technology Professional Curriculum Fall Semester RT 3000 Concepts of Clinical Care RT 3010 Introductory Radiation Physics RT 3310 Clinical Practicum I RT 3110 Clinical Aspects of Radiation Therapy Semester Total Credits 12 Winter Semester RT 5650 Pathophysiology for Health Sciences RT

  8. Radiation Safety (Revised March 2010)

    E-print Network

    Medical Use of Byproduct Material 31 Title 17California Code of Regulations 31 Responsibilities 31 Radiation Authorizations (CRAs) for radioactive materials 34 Review and approval of applications) for radiation devices 41 Setting up the radioactive materials laboratory 43 Setting up the radiation device

  9. Video Display Terminals: Radiation Issues.

    ERIC Educational Resources Information Center

    Murray, William E.

    1985-01-01

    Discusses information gathered in past few years related to health effects of video display terminals (VDTs) with particular emphasis given to issues raised by VDT users. Topics covered include radiation emissions, health concerns, radiation surveys, occupational radiation exposure standards, and long-term risks. (17 references) (EJS)

  10. Radiation Effects: Core Project

    NASA Technical Reports Server (NTRS)

    Dicello, John F.

    1999-01-01

    The risks to personnel in space from the naturally occurring radiations are generally considered to be one of the most serious limitations to human space missions, as noted in two recent reports of the National Research Council/National Academy of Sciences. The Core Project of the Radiation Effects Team for the National Space Biomedical Research Institute is the consequences of radiations in space in order to develop countermeasure, both physical and pharmaceutical, to reduce the risks of cancer and other diseases associated with such exposures. During interplanetary missions, personnel in space will be exposed to galactic cosmic rays, including high-energy protons and energetic ions with atomic masses of iron or higher. In addition, solar events will produce radiation fields of high intensity for short but irregular durations. The level of intensity of these radiations is considerably higher than that on Earth's surface, and the biological risks to astronauts is consequently increased, including increased risks of carcinogenesis and other diseases. This group is examining the risk of cancers resulting from low-dose, low-dose rate exposures of model systems to photons, protons, and iron by using ground-based accelerators which are capable of producing beams of protons, iron, and other heavy ions at energies comparable to those encountered in space. They have begun the first series of experiments using a 1-GeV iron beam at the Brookhaven National Laboratory and 250-MeV protons at Loma Linda University Medical Center's proton synchrotron facility. As part of these studies, this group will be investigating the potential for the pharmaceutical, Tamoxifen, to reduce the risk of breast cancer in astronauts exposed to the level of doses and particle types expected in space. Theoretical studies are being carried out in a collaboration between scientists at NASA's Johnson Space Center and Johns Hopkins University in parallel with the experimental program have provided methods and predictions which are being used to assess the levels of risks to be encountered and to evaluate appropriate strategies for countermeasures. Although the work in this project is primarily directed toward problems associated with space travel, the problem of protracted exposures to low-levels of radiation is one of national interest in our energy and defense programs, and the results may suggest new paradigms for addressing such risks.

  11. Pregnancy and Radiation Protection

    SciTech Connect

    Gerogiannis, J.; Stefanoyiannis, A. P.

    2010-01-21

    Several modalities are currently utilized for diagnosis and therapy, by appropriate application of x-rays. In diagnostic radiology, interventional radiology, radiotherapy, interventional cardiology, nuclear medicine and other specialties radiation protection of a pregnant woman as a patient, as well as a member of the operating personnel, is of outmost importance. Based on radiation risk, the termination of pregnancy is not justified if foetal doses are below 100 mGy. For foetal doses between 100 and 500 mGy, a decision is reached on a case by case basis. In Diagnostic Radiology, when a pregnant patient takes an abdomen CT, then an estimation of the foetus' dose is necessary. However, it is extremely rare for the dose to be high enough to justify an abortion. Radiographs of the chest and extremities can be done at any period of pregnancy, provided that the equipment is functioning properly. Usually, the radiation risk is lower than the risk of not undergoing a radiological examination. Radiation exposure in uterus from diagnostic radiological examinations is unlikely to result in any deleterious effect on the child, but the possibility of a radiation-induced effect can not be entirely ruled out. The effects of exposure to radiation on the foetus depend on the time of exposure, the date of conception and the absorbed dose. Finally, a pregnant worker can continue working in an x-ray department, as long as there is reasonable assurance that the foetal dose can be kept below 1 mGy during the pregnancy. Nuclear Medicine diagnostic examinations using short-lived radionuclides can be used for pregnant patient. Irradiation of the foetus results from placental transfer and distribution of radiopharmaceuticals in the foetal tissues, as well as from external irradiation from radioactivity in the mother's organ and tissues. As a rule, a pregnant patient should not undergo therapy with radionuclide, unless it is crucial for her life. In Radiotherapy, the patient, treating oncologist, other team and family members should carefully discuss for the decision of abortion. Important factors must be considered such as the stage and aggressiveness of the tumour, the location of the tumour, the stage of pregnancy, various therapies etc.

  12. Lunar radiation environment

    NASA Astrophysics Data System (ADS)

    Schwadron, Nathan; Spence, Harlan; Wilson, Jody

    One of the goals of the CRaTER investigation is to characterize the radiation environment near the Moon in order to enable exploration. The state-of-the-art understanding developed thus far during the LRO mission is documented in a special issue of the Spaceweather Journal entitled “Space Weather: Building the observational foundation to deduce biological effects of space radiation” (Schwadron et al., 2013a). This recently published CRaTER work probes deeper into the physics of the radiation environment at the Moon. It motivates and provides the scientific basis for new investigations in the next phase of the LRO mission. The effects of Galactic Cosmic Rays (GCRs) and Solar Energetic Particles (SEPs) range from chemical modification of the regolith, the generation of a radiation albedo that is increasingly illuminating chemical properties of the regolith, causing charging of the regolith and hazards to human explorers and robotic missions. Low-lunar orbit provides a platform for measuring SEP anisotropy over timescales of 2 hours both parallel and perpendicular to the ecliptic plane, and so far we have observed more than 18 SEP events with time-variable anisotropies during the LRO mission. Albedo proton maps of the Moon from CRaTER indicate that the flux of lunar albedo protons is correlated with elemental abundances at the lunar surface. The yield of albedo protons from the maria is 1% higher than the yield from the highlands, and there are localized peaks with even higher contrast (that may be co-located with peaks in trace elemental abundances as measured by the Lunar Prospector Gamma Ray Spectrometer). The Moon’s radiation environment both charges and affects the chemistry in the Moon’s polar regions, particularly in PSRs. This makes these regions a prime target for new CRaTER observations, since CRaTER measures GCRs and SEPs that penetrate the regolith down to 10s of cm. Thus, we review emerging discoveries from LRO/CRaTER’s remarkable exploration of moon’s radiation environment, its implications for human exploration, and its interaction with lunar regolith.

  13. Pregnancy and Radiation Protection

    NASA Astrophysics Data System (ADS)

    Gerogiannis, J.; Stefanoyiannis, A. P.

    2010-01-01

    Several modalities are currently utilized for diagnosis and therapy, by appropriate application of x-rays. In diagnostic radiology, interventional radiology, radiotherapy, interventional cardiology, nuclear medicine and other specialties radiation protection of a pregnant woman as a patient, as well as a member of the operating personnel, is of outmost importance. Based on radiation risk, the termination of pregnancy is not justified if foetal doses are below 100 mGy. For foetal doses between 100 and 500 mGy, a decision is reached on a case by case basis. In Diagnostic Radiology, when a pregnant patient takes an abdomen CT, then an estimation of the foetus' dose is necessary. However, it is extremely rare for the dose to be high enough to justify an abortion. Radiographs of the chest and extremities can be done at any period of pregnancy, provided that the equipment is functioning properly. Usually, the radiation risk is lower than the risk of not undergoing a radiological examination. Radiation exposure in uterus from diagnostic radiological examinations is unlikely to result in any deleterious effect on the child, but the possibility of a radiation-induced effect can not be entirely ruled out. The effects of exposure to radiation on the foetus depend on the time of exposure, the date of conception and the absorbed dose. Finally, a pregnant worker can continue working in an x-ray department, as long as there is reasonable assurance that the foetal dose can be kept below 1 mGy during the pregnancy. Nuclear Medicine diagnostic examinations using short-lived radionuclides can be used for pregnant patient. Irradiation of the foetus results from placental transfer and distribution of radiopharmaceuticals in the foetal tissues, as well as from external irradiation from radioactivity in the mother's organ and tissues. As a rule, a pregnant patient should not undergo therapy with radionuclide, unless it is crucial for her life. In Radiotherapy, the patient, treating oncologist, other team and family members should carefully discuss for the decision of abortion. Important factors must be considered such as the stage and aggressiveness of the tumour, the location of the tumour, the stage of pregnancy, various therapies etc.

  14. Space Radiation Cancer Risks

    NASA Technical Reports Server (NTRS)

    Cucinotta, Francis A.

    2007-01-01

    Space radiation presents major challenges to astronauts on the International Space Station and for future missions to the Earth s moon or Mars. Methods used to project risks on Earth need to be modified because of the large uncertainties in projecting cancer risks from space radiation, and thus impact safety factors. We describe NASA s unique approach to radiation safety that applies uncertainty based criteria within the occupational health program for astronauts: The two terrestrial criteria of a point estimate of maximum acceptable level of risk and application of the principle of As Low As Reasonably Achievable (ALARA) are supplemented by a third requirement that protects against risk projection uncertainties using the upper 95% confidence level (CL) in the radiation cancer projection model. NASA s acceptable level of risk for ISS and their new lunar program have been set at the point-estimate of a 3-percent risk of exposure induced death (REID). Tissue-averaged organ dose-equivalents are combined with age at exposure and gender-dependent risk coefficients to project the cumulative occupational radiation risks incurred by astronauts. The 95% CL criteria in practice is a stronger criterion than ALARA, but not an absolute cut-off as is applied to a point projection of a 3% REID. We describe the most recent astronaut dose limits, and present a historical review of astronaut organ doses estimates from the Mercury through the current ISS program, and future projections for lunar and Mars missions. NASA s 95% CL criteria is linked to a vibrant ground based radiobiology program investigating the radiobiology of high-energy protons and heavy ions. The near-term goal of research is new knowledge leading to the reduction of uncertainties in projection models. Risk projections involve a product of many biological and physical factors, each of which has a differential range of uncertainty due to lack of data and knowledge. The current model for projecting space radiation cancer risk relies on the three assumptions of linearity, additivity, and scaling along with the use of population averages. We describe uncertainty estimates for this model, and new experimental data that sheds light on the accuracy of the underlying assumptions. These methods make it possible to express risk management objectives in terms of quantitative metrics, i.e., the number of days in space without exceeding a given risk level within well defined confidence limits. The resulting methodology is applied to several human space exploration mission scenarios including lunar station, deep space outpost, and a Mars mission. Factors that dominate risk projection uncertainties and application of this approach to assess candidate mitigation approaches are described.

  15. Acute Cerebrovascular Radiation Syndrome: Radiation Neurotoxicity , mechanisms of CNS radiation injury, advanced countermeasures for Radiation Protection of Central Nervous System.

    NASA Astrophysics Data System (ADS)

    Popov, Dmitri; Jones, Jeffrey; Maliev, Slava

    Key words: Cerebrovascular Acute Radiation Syndrome (Cv ARS), Radiation Neurotoxins (RNT), Neurotransmitters, Radiation Countermeasures, Antiradiation Vaccine (ArV), Antiradiation Blocking Antibodies, Antiradiation Antidote. Psychoneuroimmunology, Neurotoxicity. ABSTRACT: To review the role of Radiation Neurotoxins in triggering, developing of radiation induced central nervous system injury. Radiation Neurotoxins - rapidly acting blood toxic lethal agent, which activated after irradiation and concentrated, circulated in interstitial fluid, lymph, blood with interactions with cell membranes, receptors and cell compartments. Radiation Neurotoxins - biological molecules with high enzymatic activity and/or specific lipids and activated or modified after irradiation. The Radiation Neurotoxins induce increased permeability of blood vessels, disruption of the blood-brain barrier, blood-cerebrospinal fluid (CSF) barrier and developing severe disorder of blood macro- and micro-circulation. Principles of Radiation Psychoneuro-immunology and Psychoneuro-allergology were applied for determination of pathological processes developed after irradiation or selective administration of Radiation Neurotoxins to radiation naïve mammals. Effects of radiation and exposure to radiation can develop severe irreversible abnormalities of Central Nervous System, brain structures and functions. Antiradiation Vaccine - most effective, advanced methods of protection, prevention, mitigation and treatment and was used for of Acute Radiation Syndromes and elaboration of new technology for immune-prophylaxis and immune-protection against ?, Heavy Ion, Neutron irradiation. Results of experiments suggested that blocking, antitoxic, antiradiation antibodies can significantly reduce toxicity of Radiation Toxins. New advanced technology include active immune-prophylaxis with Antiradiation Vaccine and Antiradiation therapy that included specific blocking antibodies to Radiation Neurotoxins. Antiradiation Vaccine and Antiradiation IgG preparations - prospective effective antidote/countermeasure for ?-irradiation, heavy ions irradiation, neutron irradiation. Recommendations for treatment and immune-prophylaxis of CNS injury, induced by radiation, were proposed. Specific immune therapy and specific immune prophylaxis reduce symptoms of ACvRS. This manuscript summarizes the results of experiments and considering possibility for blocking toxicological mechanisms of action of Radiation and Radiation Neurotoxins and prevention or diminishing clinical signs of injury of CNS. Experimental data suggest that Antiradiation vaccine and Antiradiation IgG with specific antibodies to Radiation Neurotoxins, Cytotoxins protect CNS against high doses of radiation.

  16. Modeling gradual diffusion changes in radiation belt electron phase space density for the March 2013 Van Allen Probes case study

    NASA Astrophysics Data System (ADS)

    Li, Zhao; Hudson, Mary; Jaynes, Allison; Boyd, Alexander; Malaspina, David; Thaller, Scott; Wygant, John; Henderson, Michael

    2014-10-01

    March 2013 provided the first equinoctial period when all of the instruments on the Van Allen Probes spacecraft were fully operational. This interval was characterized by disturbances of outer zone electrons with two time scales of variation, diffusive and rapid dropout and restoration. A radial diffusion model was applied to the monthlong interval to confirm that electron phase space density is well described by radial diffusion for the whole month at low first invariant ? 400 MeV/G but peaks in phase space density observed by the Energetic Particle, Composition, and Thermal Plasma (ECT) instrument suite at higher first invariant are not reproduced by radial transport from a source at higher L. The model does well for much of the monthlong interval, capturing three of four enhancements in phase space density which emerge from the outer boundary, while the strong enhancement following dropout on 17-18 March requires local acceleration at higher first invariant (M=1000 MeV/G versus 200 MeV/G) not included in our model. We have incorporated phase space density from ECT measurement at the outer boundary and plasmapause determination from the Electric Field and Waves (EFW) instrument to separate hiss and chorus loss models.

  17. A deterministic method to characterize canopy radiative transfer properties

    NASA Astrophysics Data System (ADS)

    Link, Timothy E.; Marks, Danny; Hardy, Janet P.

    2004-12-01

    Investigations of snowcover dynamics beneath vegetation canopies require either measured or estimated solar and thermal radiation values at the snow surface. A deterministic method is presented that uses portable arrays of pyranometers and pyrgeometers to quantify the amount of incoming radiation at the snow surface. Example solar and thermal radiation datasets are presented from boreal deciduous, boreal coniferous and temperate coniferous forest stands. The data indicate that the canopies transmitted 33% (4-8 March), 15% (6-10 February), and 3% (22-24 September) of the above-canopy radiation. In the boreal deciduous and temperate conifer stands, thermal radiation is increased by 25% and 34% respectively. Thermal gains partially offset solar reduction, such that incoming all-wave radiation is decreased by 22% and 25% respectively for each of these stands. When recorded at a high temporal resolution, array data can estimate below-canopy diffuse solar radiation values for estimation techniques that treat direct and diffuse transmission independently. We provide examples of how radiometer array data are used to derive simple canopy radiation transmissivity parameters for global, beam and diffuse radiation. Radiometer arrays also provide data for detailed investigations to assess within-stand radiation variability, or to investigate radiation variations across land cover discontinuities, to advance our understanding of snowcover energetics in complex environments. Copyright

  18. The Fukushima radiation accident: consequences for radiation accident medical management.

    PubMed

    Meineke, Viktor; Dörr, Harald

    2012-08-01

    The March 2011 radiation accident in Fukushima, Japan, is a textbook example of a radiation accident of global significance. In view of the global dimensions of the accident, it is important to consider the lessons learned. In this context, emphasis must be placed on consequences for planning appropriate medical management for radiation accidents including, for example, estimates of necessary human and material resources. The specific characteristics of the radiation accident in Fukushima are thematically divided into five groups: the exceptional environmental influences on the Fukushima radiation accident, particular circumstances of the accident, differences in risk perception, changed psychosocial factors in the age of the Internet and globalization, and the ignorance of the effects of ionizing radiation both among the general public and health care professionals. Conclusions like the need for reviewing international communication, interfacing, and interface definitions will be drawn from the Fukushima radiation accident. PMID:22951483

  19. Radiation dosimetry and biophysical models of space radiation effects

    NASA Technical Reports Server (NTRS)

    Cucinotta, Francis A.; Wu, Honglu; Shavers, Mark R.; George, Kerry

    2003-01-01

    Estimating the biological risks from space radiation remains a difficult problem because of the many radiation types including protons, heavy ions, and secondary neutrons, and the absence of epidemiology data for these radiation types. Developing useful biophysical parameters or models that relate energy deposition by space particles to the probabilities of biological outcomes is a complex problem. Physical measurements of space radiation include the absorbed dose, dose equivalent, and linear energy transfer (LET) spectra. In contrast to conventional dosimetric methods, models of radiation track structure provide descriptions of energy deposition events in biomolecules, cells, or tissues, which can be used to develop biophysical models of radiation risks. In this paper, we address the biophysical description of heavy particle tracks in the context of the interpretation of both space radiation dosimetry and radiobiology data, which may provide insights into new approaches to these problems.

  20. Multilayer radiation shield

    DOEpatents

    Urbahn, John Arthur (Saratoga Springs, NY); Laskaris, Evangelos Trifon (Niskayuna, NY)

    2009-06-16

    A power generation system including: a generator including a rotor including a superconductive rotor coil coupled to a rotatable shaft; a first prime mover drivingly coupled to the rotatable shaft; and a thermal radiation shield, partially surrounding the rotor coil, including at least a first sheet and a second sheet spaced apart from the first sheet by centripetal force produced by the rotatable shaft. A thermal radiation shield for a generator including a rotor including a super-conductive rotor coil including: a first sheet having at least one surface formed from a low emissivity material; and at least one additional sheet having at least one surface formed from a low emissivity material spaced apart from the first sheet by centripetal force produced by the rotatable shaft, wherein each successive sheet is an incrementally greater circumferential arc length and wherein the centripetal force shapes the sheets into a substantially catenary shape.

  1. National Ambient Radiation Database

    SciTech Connect

    Dziuban, J.; Sears, R.

    2003-02-25

    The U.S. Environmental Protection Agency (EPA) recently developed a searchable database and website for the Environmental Radiation Ambient Monitoring System (ERAMS) data. This site contains nationwide radiation monitoring data for air particulates, precipitation, drinking water, surface water and pasteurized milk. This site provides location-specific as well as national information on environmental radioactivity across several media. It provides high quality data for assessing public exposure and environmental impacts resulting from nuclear emergencies and provides baseline data during routine conditions. The database and website are accessible at www.epa.gov/enviro/. This site contains (1) a query for the general public which is easy to use--limits the amount of information provided, but includes the ability to graph the data with risk benchmarks and (2) a query for a more technical user which allows access to all of the data in the database, (3) background information on ER AMS.

  2. Radiation Induced Genomic Instability

    SciTech Connect

    Morgan, William F.

    2011-03-01

    Radiation induced genomic instability can be observed in the progeny of irradiated cells multiple generations after irradiation of parental cells. The phenotype is well established both in vivo (Morgan 2003) and in vitro (Morgan 2003), and may be critical in radiation carcinogenesis (Little 2000, Huang et al. 2003). Instability can be induced by both the deposition of energy in irradiated cells as well as by signals transmitted by irradiated (targeted) cells to non-irradiated (non-targeted) cells (Kadhim et al. 1992, Lorimore et al. 1998). Thus both targeted and non-targeted cells can pass on the legacy of radiation to their progeny. However the radiation induced events and cellular processes that respond to both targeted and non-targeted radiation effects that lead to the unstable phenotype remain elusive. The cell system we have used to study radiation induced genomic instability utilizes human hamster GM10115 cells. These cells have a single copy of human chromosome 4 in a background of hamster chromosomes. Instability is evaluated in the clonal progeny of irradiated cells and a clone is considered unstable if it contains three or more metaphase sub-populations involving unique rearrangements of the human chromosome (Marder and Morgan 1993). Many of these unstable clones have been maintained in culture for many years and have been extensively characterized. As initially described by Clutton et al., (Clutton et al. 1996) many of our unstable clones exhibit persistently elevated levels of reactive oxygen species (Limoli et al. 2003), which appear to be due dysfunctional mitochondria (Kim et al. 2006, Kim et al. 2006). Interestingly, but perhaps not surprisingly, our unstable clones do not demonstrate a “mutator phenotype” (Limoli et al. 1997), but they do continue to rearrange their genomes for many years. The limiting factor with this system is the target – the human chromosome. While some clones demonstrate amplification of this chromosome and thus lend themselves to prolonged study, many tend to eliminate or rearrange the target chromosome until it is too small for further rearrangement. The observed frequency of induced instability by low and high linear-energy-transfer radiations greatly exceeds that observed for nuclear gene mutations at similar doses; hence, mutation of a gene or gene family is unlikely to be the initiating mechanism. Once initiated however, there is evidence in the GM10115 model system that it can be perpetuated over time by dicentric chromosome formation followed by bridge breakage fusion cycles (Marder and Morgan 1993), as well as recombinational events involving interstitial telomere like repeat sequences (Day et al. 1998). There is also increasing evidence that inflammatory type reactions (Lorimore et al. 2001, Lorimore and Wright 2003), presumably involving reactive oxygen and nitrogen species as well as cytokines and chemokines might be involved in driving the ustable phenotype (Liaikis et al. 2007, Hei et al. 2008). To this end there is very convincing evidence for such reactions being involved in another non-targeted effect associated with ionizing radiation, the bystander effect (Hei et al. 2008). Clearly the link between induced instability and bystander effects suggests common processes and inflammatory type reactions will likely be the subject of future investigation.

  3. TOPEX orbital radiation study

    NASA Technical Reports Server (NTRS)

    Stassinopoulos, E. G.; Barth, J. M.

    1984-01-01

    The space radiation environment of the TOPEX spacecraft is investigated. A single trajectory was considered. The external (surface incident) charged particle radiation, predicted for the satellite, is determined by orbital flux integration for the specified trajectory. The latest standard models of the environment are used in the calculations. The evaluation is performed for solar maximum conditions. The spacecraft exposure to cosmic rays of galactic origin is evaluated over its flight path through the magnetosphere in terms of geomagnetic shielding effects, both for surface incident heavy ions and for particles emerging behind different material thickness. Limited shielding and dose evaluations are performed for simple infinite slab and spherical geometries. Results, given in graphical and tabular form, are analyzed, explained, and discussed. Conclusions are presented and commented on.

  4. Radiation Environment Inside Spacecraft

    NASA Technical Reports Server (NTRS)

    O'Neill, Patrick

    2015-01-01

    Dr. Patrick O'Neill, NASA Johnson Space Center, will present a detailed description of the radiation environment inside spacecraft. The free space (outside) solar and galactic cosmic ray and trapped Van Allen belt proton spectra are significantly modified as these ions propagate through various thicknesses of spacecraft structure and shielding material. In addition to energy loss, secondary ions are created as the ions interact with the structure materials. Nuclear interaction codes (FLUKA, GEANT4, HZTRAN, MCNPX, CEM03, and PHITS) transport free space spectra through different thicknesses of various materials. These "inside" energy spectra are then converted to Linear Energy Transfer (LET) spectra and dose rate - that's what's needed by electronics systems designers. Model predictions are compared to radiation measurements made by instruments such as the Intra-Vehicular Charged Particle Directional Spectrometer (IV-CPDS) used inside the Space Station, Orion, and Space Shuttle.

  5. Ultraviolet radiation effects

    NASA Technical Reports Server (NTRS)

    Slemp, Wayne S.

    1989-01-01

    Solar ultraviolet testing was not developed which will provide highly accelerated (20 to 50X) exposures that correlate to flight test data. Additional studies are required to develop an exposure methodology which will assure that accelerated testing can be used for qualification of materials and coatings for long duration space flight. Some conclusions are listed: Solar UV radiation is present in all orbital environments; Solar UV does not change in flux with orbital altitude; UV radiation can degrade most coatings and polymeric films; Laboratory UV simulation methodology is needed for accelerated testing to 20 UV solar constants; Simulation of extreme UV (below 200 nm) is needed to evaluate requirements for EUV in solar simulation.

  6. Semiconductor radiation detector

    DOEpatents

    Patt, Bradley E. (Sherman Oaks, CA); Iwanczyk, Jan S. (Los Angeles, CA); Tull, Carolyn R. (Orinda, CA); Vilkelis, Gintas (Westlake Village, CA)

    2002-01-01

    A semiconductor radiation detector is provided to detect x-ray and light photons. The entrance electrode is segmented by using variable doping concentrations. Further, the entrance electrode is physically segmented by inserting n+ regions between p+ regions. The p+ regions and the n+ regions are individually biased. The detector elements can be used in an array, and the p+ regions and the n+ regions can be biased by applying potential at a single point. The back side of the semiconductor radiation detector has an n+ anode for collecting created charges and a number of p+ cathodes. Biased n+ inserts can be placed between the p+ cathodes, and an internal resistor divider can be used to bias the n+ inserts as well as the p+ cathodes. A polysilicon spiral guard can be implemented surrounding the active area of the entrance electrode or surrounding an array of entrance electrodes.

  7. Handheld CZT radiation detector

    DOEpatents

    Murray, William S.; Butterfield, Kenneth B.; Baird, William

    2004-08-24

    A handheld CZT radiation detector having a CZT gamma-ray sensor, a multichannel analyzer, a fuzzy-logic component, and a display component is disclosed. The CZT gamma-ray sensor may be a coplanar grid CZT gamma-ray sensor, which provides high-quality gamma-ray analysis at a wide range of operating temperatures. The multichannel analyzer categorizes pulses produce by the CZT gamma-ray sensor into channels (discrete energy levels), resulting in pulse height data. The fuzzy-logic component analyzes the pulse height data and produces a ranked listing of radioisotopes. The fuzzy-logic component is flexible and well-suited to in-field analysis of radioisotopes. The display component may be a personal data assistant, which provides a user-friendly method of interacting with the detector. In addition, the radiation detector may be equipped with a neutron sensor to provide an enhanced mechanism of sensing radioactive materials.

  8. Genetic susceptibility to radiation

    NASA Astrophysics Data System (ADS)

    Hall, E. J.; Brenner, D. J.; Worgul, B.; Smilenov, L.

    In the context of space radiation, it is important to know whether the human population includes genetically predisposed radiosensitive subsets. One possibility is that haploinsufficiency for ATM confers radiosensitivity, and this defect involves 1-3% of the population. Using knock-out mice we chose to study cataractogenesis in the lens and oncogenic transformation in mouse embryo fibroblasts to assay for effects of ATM deficiency. Radiation induced cataracts appeared earlier in the heterozygous versus wild-type animals following exposure to either gamma rays or 1 GeV/nucleon iron ions. In addition, it was found that embryo fibroblasts of Atm heterozygotes showed an increased incidence of oncogenic transformation compared with their normal litter-matched counterparts. From these data we suggest that Ataxia Telangiectasia heterozygotes could indeed represent a societally-significant radiosensitive subpopulation.

  9. Radiation degradation of cellulose

    NASA Astrophysics Data System (ADS)

    Leonhardt, J.; Arnold, G.; Baer, M.; Langguth, H.; Gey, M.; Hübert, S.

    The application of straw and other cellulose polymers as feedstuff for ruminants is limited by its low digestibility. During recent decades it was attempted to increase the digestibility of straw by several chemical and physical methods. In this work some results of the degradation of gamma and electron treated wheat straw are reported. Complex methods of treatment (e.g. radiation influence and influence of lyes) are taken into consideration. In vitro-experiments with radiation treated straw show that the digestibility can be increased from 20 % up to about 80 %. A high pressure liquid chromatography method was used to analyze the hydrolysates. The contents of certain species of carbohydrates in the hydrolysates in dependence on the applied dose are given.

  10. Biochemistry of ionizing radiation

    SciTech Connect

    Walden, T.L.; Nushin, F.K.

    1990-01-01

    This volume examines the biochemical changes occurring in normal tissue after irradiation. A review of radiation chemistry is followed by an analysis of factors affecting biochemical responses and a timely discussion of radiobiology in space flight. The authors then describe the effects of radiation on lipid peroxidation, amino acids, peptides, proteins, polysaccharides, DNA, thiols, and body fluids. Close attention is given to alterations in biological mediators such as eicosanoids, cyclic nucleotides, angiotensin, histamine, polyamines, catecholamines, and serotonin and in hormones such as adrenocorticotropic hormone, testosterone, estrogens, follicle-stimulating hormone, luteinizing hormone, thyroid hormones, insulin and glucagon, gastrin, and melatonin. Other chapters focus on changes in carbohydrate metabolism, oxidative phosphorylation, protein synthesis, and serum proteins. A chapter on biological dosimeters discusses prodromal syndrome, hematological dosimeters, serum composition, urine, chromosomal aberrations, and fluorometric and immunoassays.

  11. Terahertz radiation mixer

    DOEpatents

    Wanke, Michael C. (Albuquerque, NM); Allen, S. James (Santa Barbara, CA); Lee, Mark (Albuquerque, NM)

    2008-05-20

    A terahertz radiation mixer comprises a heterodyned field-effect transistor (FET) having a high electron mobility heterostructure that provides a gatable two-dimensional electron gas in the channel region of the FET. The mixer can operate in either a broadband pinch-off mode or a narrowband resonant plasmon mode by changing a grating gate bias of the FET. The mixer can beat an RF signal frequency against a local oscillator frequency to generate an intermediate frequency difference signal in the microwave region. The mixer can have a low local oscillator power requirement and a large intermediate frequency bandwidth. The terahertz radiation mixer is particularly useful for terahertz applications requiring high resolution.

  12. Radiation shielding composition

    DOEpatents

    Quapp, W.J.; Lessing, P.A.

    1998-07-28

    A composition is disclosed for use as a radiation shield. The shield is a concrete product containing a stable uranium aggregate for attenuating gamma rays and a neutron absorbing component, the uranium aggregate and neutron absorbing component being present in the concrete product in sufficient amounts to provide a concrete having a density between about 4 and about 15 grams/cm{sup 3} and which will at a predetermined thickness, attenuate gamma rays and absorb neutrons from a radioactive material of projected gamma ray and neutron emissions over a determined time period. The composition is preferably in the form of a container for storing radioactive materials that emit gamma rays and neutrons. The concrete container preferably comprises a metal liner and/or a metal outer shell. The resulting radiation shielding container has the potential of being structurally sound, stable over a long period of time, and, if desired, readily mobile. 5 figs.

  13. Genesis Radiation Environment

    NASA Technical Reports Server (NTRS)

    Minow, Joseph I.; Altstatt, Richard L.; Skipworth, William C.

    2007-01-01

    The Genesis spacecraft launched on 8 August 2001 sampled solar wind environments at L1 from 2001 to 2004. After the Science Capsule door was opened, numerous foils and samples were exposed to the various solar wind environments during periods including slow solar wind from the streamer belts, fast solar wind flows from coronal holes, and coronal mass ejections. The Survey and Examination of Eroded Returned Surfaces (SEERS) program led by NASA's Space Environments and Effects program had initiated access for the space materials community to the remaining Science Capsule hardware after the science samples had been removed for evaluation of materials exposure to the space environment. This presentation will describe the process used to generate a reference radiation Genesis Radiation Environment developed for the SEERS program for use by the materials science community in their analyses of the Genesis hardware.

  14. Time encoded radiation imaging

    SciTech Connect

    Marleau, Peter; Brubaker, Erik; Kiff, Scott

    2014-10-21

    The various technologies presented herein relate to detecting nuclear material at a large stand-off distance. An imaging system is presented which can detect nuclear material by utilizing time encoded imaging relating to maximum and minimum radiation particle counts rates. The imaging system is integrated with a data acquisition system that can utilize variations in photon pulse shape to discriminate between neutron and gamma-ray interactions. Modulation in the detected neutron count rates as a function of the angular orientation of the detector due to attenuation of neighboring detectors is utilized to reconstruct the neutron source distribution over 360 degrees around the imaging system. Neutrons (e.g., fast neutrons) and/or gamma-rays are incident upon scintillation material in the imager, the photons generated by the scintillation material are converted to electrical energy from which the respective neutrons/gamma rays can be determined and, accordingly, a direction to, and the location of, a radiation source identified.

  15. Radiation shielding composition

    DOEpatents

    Quapp, William J. (Idaho Falls, ID); Lessing, Paul A. (Idaho Falls, ID)

    1998-01-01

    A composition for use as a radiation shield. The shield is a concrete product containing a stable uranium aggregate for attenuating gamma rays and a neutron absorbing component, the uranium aggregate and neutron absorbing component being present in the concrete product in sufficient amounts to provide a concrete having a density between about 4 and about 15 grams/cm.sup.3 and which will at a predetermined thickness, attenuate gamma rays and absorb neutrons from a radioactive material of projected gamma ray and neutron emissions over a determined time period. The composition is preferably in the form of a container for storing radioactive materials that emit gamma rays and neutrons. The concrete container preferably comprises a metal liner and/or a metal outer shell. The resulting radiation shielding container has the potential of being structurally sound, stable over a long period of time, and, if desired, readily mobile.

  16. Radiation shielding composition

    DOEpatents

    Quapp, William J. (Idaho Falls, ID); Lessing, Paul A. (Idaho Falls, ID)

    2000-12-26

    A composition for use as a radiation shield. The shield is a concrete product containing a stable uranium aggregate for attenuating gamma rays and a neutron absorbing component, the uranium aggregate and neutron absorbing component being present in the concrete product in sufficient amounts to provide a concrete having a density between about 4 and about 15 grams/cm.sup.3 and which will at a predetermined thickness, attenuate gamma rays and absorb neutrons from a radioactive material of projected gamma ray and neutron emissions over a determined time period. The composition is preferably in the form of a container for storing radioactive materials that emit gamma rays and neutrons. The concrete container preferably comprises a metal liner and/or a metal outer shell. The resulting radiation shielding container has the potential of being structurally sound, stable over a long period of time, and, if desired, readily mobile.

  17. Radiative B Decays

    SciTech Connect

    Bard, D.; /Imperial Coll., London

    2011-11-23

    I discuss recent results in radiative B decays from the Belle and BaBar collaborations. I report new measurements of the decay rate and CP asymmetries in b {yields} s{gamma} and b {yields} d{gamma} decays, and measurements of the photon spectrum in b {yields} s{gamma}. Radiative penguin decays are flavour changing neutral currents which do not occur at tree level in the standard model (SM), but must proceed via one loop or higher order diagrams. These transitions are therefore suppressed in the SM, but offer access to poorlyknown SM parameters and are also a sensitive probe of new physics. In the SM, the rate is dominated by the top quark contribution to the loop, but non-SM particles could also contribute with a size comparable to leading SM contributions. The new physics effects are potentially large which makes them theoretically very interesting, but due to their small branching fractions they are typically experimentally challenging.

  18. Provisional standards of radiation safety during flights

    NASA Technical Reports Server (NTRS)

    1977-01-01

    Radiation effects during space flights are discussed in the context of the sources and dangers of such radiation and the radiobiological prerequisites for establishing safe levels of radiation dosage. Standard safe levels of radiation during space flight are established.

  19. January 2015 Ultraviolet Radiation Producing Device Guidelines

    E-print Network

    Nicholson, Bruce J.

    January 2015 Ultraviolet Radiation Producing Device Guidelines Scope: This guidance document and available safety guidelines for using UV radiation. Background: Ultraviolet (UV) Radiation is divided radiation can be associated with adverse health effects such as erythema, photokeratitis, skin cancer

  20. Radiation Therapy for Soft Tissue Sarcomas

    MedlinePLUS

    ... sarcomas Next Topic Chemotherapy for soft tissue sarcomas Radiation therapy for soft tissue sarcomas Radiation therapy uses ... spread. This is called palliative treatment . Types of radiation therapy External beam radiation therapy: For this treatment, ...

  1. Radiation-induced schwannomas

    SciTech Connect

    Rubinstein, A.B.; Reichenthal, E.; Borohov, H.

    1989-06-01

    The histopathology and clinical course of three patients with schwannomas of the brain and high cervical cord after therapeutic irradiation for intracranial malignancy and for ringworm of the scalp are described. Earlier reports in the literature indicated that radiation of the scalp may induce tumors in the head and neck. It is therefore suggested that therapeutic irradiation in these instances was a causative factor in the genesis of these tumors.

  2. Radiation in Yolo County

    NASA Astrophysics Data System (ADS)

    Dickie, H.; Colwell, K.

    2013-12-01

    In today's post-nuclear age, there are many man-made sources of radioactivity, in addition to the natural background we expect from cosmic and terrestrial origins. While all atoms possess unstable isotopes, there are few that are abundant enough, energetic enough, and have long enough half-lives to pose a signicant risk of ionizing radiation exposure. We hypothesize a decreasing relative radiation measurement (in detected counts per minute [CPM]) at nine locations that might pose occupational or environmental hazard: 1. A supermarket produce aisle (living tissue has high concentration of 40K) 2. A hospital (medical imaging uses X-rays and radioactive dyes) 3. The electronics section of a superstore (high voltage electronics have the potential to produce ionizing radiation) 4. An electrical transformer (similar reasons) 5. An antique store (some ceramics and glazes use radioisotopes that are now outlawed) 6. A gasoline pump (processing and terrestrial isotope contamination might leave a radioactive residue) 7. A fertilized eld (phosphate rock contains uranium and thorium, in addition to potassium) 8. A house (hopefully mild background, but potential radon contamination) 9. A school (should be radiologically neutral) We tested the hypothesis by measuring 100 minutes of counts on a self-assembled MightyOhmTM Geiger counter at each location. Our results show that contrary to the hypothesized ordering, the house was the most radiologically active. We present possible explanations for the observed radiation levels, as well as possible sources of measurement error, possible consequences of prolonged exposure to the measured levels, and suggestions for decreasing exposure and environmental impact.

  3. Radiation biology of mosquitoes

    PubMed Central

    Helinski, Michelle EH; Parker, Andrew G; Knols, Bart GJ

    2009-01-01

    There is currently renewed interest in assessing the feasibility of the sterile insect technique (SIT) to control African malaria vectors in designated areas. The SIT relies on the sterilization of males before mass release, with sterilization currently being achieved through the use of ionizing radiation. This paper reviews previous work on radiation sterilization of Anopheles mosquitoes. In general, the pupal stage was irradiated due to ease of handling compared to the adult stage. The dose-response curve between the induced sterility and log (dose) was shown to be sigmoid, and there was a marked species difference in radiation sensitivity. Mating competitiveness studies have generally been performed under laboratory conditions. The competitiveness of males irradiated at high doses was relatively poor, but with increasing ratios of sterile males, egg hatch could be lowered effectively. Males irradiated as pupae had a lower competitiveness compared to males irradiated as adults, but the use of partially-sterilizing doses has not been studied extensively. Methods to reduce somatic damage during the irradiation process as well as the use of other agents or techniques to induce sterility are discussed. It is concluded that the optimal radiation dose chosen for insects that are to be released during an SIT programme should ensure a balance between induced sterility of males and their field competitiveness, with competitiveness being determined under (semi-) field conditions. Self-contained 60Co research irradiators remain the most practical irradiators but these are likely to be replaced in the future by a new generation of high output X ray irradiators. PMID:19917076

  4. Three-dimensional visualization of morphology and ventilation procedure (air flow and diffusion) of a subdivision of the acinus using synchrotron radiation microtomography of the human lung specimens

    NASA Astrophysics Data System (ADS)

    Shimizu, Kenji; Ikura, Hirohiko; Ikezoe, Junpei; Nagareda, Tomofumi; Yagi, Naoto; Umetani, Keiji; Imai, Yutaka

    2004-04-01

    We have previously reported a synchrotron radiation (SR) microtomography system constructed at the bending magnet beamline at the SPring-8. This system has been applied to the lungs obtained at autopsy and inflated and fixed by Heitzman"s method. Normal lung and lung specimens with two different types of pathologic processes (fibrosis and emphysema) were included. Serial SR microtomographic images were stacked to yield the isotropic volumetric data with high-resolution (12 ?m3 in voxel size). Within the air spaces of a subdivision of the acinus, each voxel is segmented three-dimensionally using a region growing algorithm ("rolling ball algorithm"). For each voxel within the segmented air spaces, two types of voxel coding have been performed: single-seeded (SS) coding and boundary-seeded (BS) coding, in which the minimum distance from an initial point as the only seed point and all object boundary voxels as a seed set were calculated and assigned as the code values to each voxel, respectively. With these two codes, combinations of surface rendering and volume rendering techniques were applied to visualize three-dimensional morphology of a subdivision of the acinus. Furthermore, sequentially filling process of air into a subdivision of the acinus was simulated under several conditions to visualize the ventilation procedure (air flow and diffusion). A subdivision of the acinus was reconstructed three-dimensionally, demonstrating the normal architecture of the human lung. Significant differences in appearance of ventilation procedure were observed between normal and two pathologic processes due to the alteration of the lung architecture. Three-dimensional reconstruction of the microstructure of a subdivision of the acinus and visualization of the ventilation procedure (air flow and diffusion) with SR microtomography would offer a new approach to study the morphology, physiology, and pathophysiology of the human respiratory system.

  5. Uninformed Hawking radiation

    NASA Astrophysics Data System (ADS)

    Sakalli, I.; Ovgun, A.

    2015-04-01

    We show in detail that the Parikh-Wilczek tunneling method (PWTM), which was designed for resolving the information loss problem in Hawking radiation (HR) fails whenever the radiation occurs from an isothermal process. The PWTM aims to produce a non-thermal HR which adumbrates the resolution of the problem of unitarity in quantum mechanics (QM), and consequently the entropy (or information) conservation problem. The effectiveness of the method has been satisfactorily tested on numerous black holes (BHs). However, it has been shown that the isothermal HR, which results from the emission of the uncharged particles of the linear dilaton BH (LDBH) described in the Einstein-Maxwell-Dilaton (EMD) theory, the PWTM has vulnerability in having non-thermal radiation. In particular, we consider Painlevé-Gullstrand coordinates (PGCs) and isotropic coordinates (ICs) in order to prove the aforementioned failure in the PWTM. While carrying out calculations in the ICs, we also highlight the effect of the refractive index on the null geodesics.

  6. Fundamentals of Atmospheric Radiation

    NASA Astrophysics Data System (ADS)

    Bohren, Craig F.; Clothiaux, Eugene E.

    2006-02-01

    This textbook fills a gap in the literature for teaching material suitable for students of atmospheric science and courses on atmospheric radiation. It covers the fundamentals of emission, absorption, and scattering of electromagnetic radiation from ultraviolet to infrared and beyond. Much of the book applies to planetary atmosphere. The authors are physicists and teach at the largest meteorology department of the US at Penn State. Craig T. Bohren has taught the atmospheric radiation course there for the past 20 years with no book. Eugene Clothiaux has taken over and added to the course notes. Problems given in the text come from students, colleagues, and correspondents. The design of the figures especially for this book is meant to ease comprehension. Discussions have a graded approach with a thorough treatment of subjects, such as single scattering by particles, at different levels of complexity. The discussion of the multiple scattering theory begins with piles of plates. This simple theory introduces concepts in more advanced theories, i.e. optical thickness, single-scattering albedo, asymmetry parameter. The more complicated theory, the two-stream theory, then takes the reader beyond the pile-of-plates theory. Ideal for advanced undergraduate and graduate students of atmospheric science.

  7. Intraocular radiation blocking.

    PubMed

    Finger, P T; Ho, T K; Fastenberg, D M; Hyman, R A; Stroh, E M; Packer, S; Perry, H D

    1990-09-01

    Iodine-based liquid radiographic contrast agents were placed in normal and tumor-bearing (Greene strain) rabbit eyes to evaluate their ability to block iodine-125 radiation. This experiment required the procedures of tumor implantation, vitrectomy, air-fluid exchange, and 125I plaque and thermoluminescent dosimetry (TLD) chip implantation. The authors quantified the amount of radiation attenuation provided by intraocularly placed contrast agents with in vivo dosimetry. After intraocular insertion of a blocking agent or sham blocker (saline) insertion, episcleral 125I plaques were placed across the eye from episcleral TLD dosimeters. This showed that radiation attenuation occurred after blocker insertion compared with the saline controls. Then computed tomographic imaging techniques were used to describe the relatively rapid transit time of the aqueous-based iohexol compared with the slow transit time of the oil-like iophendylate. Lastly, seven nontumor-bearing eyes were primarily examined for blocking agent-related ocular toxicity. Although it was noted that iophendylate induced intraocular inflammation and retinal degeneration, all iohexol-treated eyes were similar to the control eyes at 7 and 31 days of follow-up. Although our study suggests that intraocular radiopaque materials can be used to shield normal ocular structures during 125I plaque irradiation, a mechanism to keep these materials from exiting the eye must be devised before clinical application. PMID:2211021

  8. Radiation Protection in Canada

    PubMed Central

    Bird, P. M.

    1964-01-01

    The current status of radiation protection in Canada is discussed in the second of a three-part series and particular emphasis is placed on the role of the Radiation Protection Division of the Department of National Health and Welfare. Administrative and operational control procedures have been developed, involving prior approval of health safeguards in the radioisotope user's facilities and techniques, and systematic monitoring and inspection. Where necessary, a medical follow-up of accidents and excessive radiation exposures is carried out. In 1963 more than 1600 radioisotope licences were issued. Filmmonitoring service was provided to about 15,500 isotope and x-ray workers. Semiautomatic handling procedures have been developed to meet the increasing demand for film-monitoring services. Monitoring and inspection services have been provided for x-ray workers, and a committee has been formed to develop administrative procedures for health and safety control in x-ray work. Committees have also been set up to review the health and safety aspects of the operation of nuclear reactors and particle accelerators. PMID:14146856

  9. Radiation belt probes launched

    NASA Astrophysics Data System (ADS)

    Showstack, Randy

    2012-09-01

    Storms on Earth delayed by only a few days the launch of NASA's Radiation Belt Storm Probes (RBSP), which blasted off on 30 August for a 2-year tour to explore the Van Allen radiation belts. The two satellites will help scientists learn about the processes that affect electrons and ions in the donut-shaped belts and how the belts change in the context of geomagnetic storms. “The information collected from these probes will benefit the public by allowing us to better protect our satellites and understand how space weather affects communications and technology on Earth,” said John Grunsfeld, associate administrator for NASA's Science Mission Directorate. Each probe carries an identical suite of instruments, including an Energetic Particle, Composition, and Thermal Plasma Suite; Electric and Magnetic Field Instrument Suite and Integrated Science; Electric Field and Waves Suite; Radiation Belt Storm Probes Ion Composition Experiment; and Relativistic Proton Spectrometer. RBSP is part of NASA's Living With a Star program and is managed for NASA by the Johns Hopkins University's Applied Physics Laboratory. For more information, see http://rbsp.jhuapl.edu.

  10. Radiation takes its Toll.

    PubMed

    Ratikan, Josephine A; Micewicz, Ewa D; Xie, Michael W; Schaue, Dörthe

    2015-11-28

    The ability to recognize and respond to universal molecular patterns on invading microorganisms allows our immune system to stay on high alert, sensing danger to our self-integrity. Our own damaged cells and tissues in pathological situations activate similar warning systems as microbes. In this way, the body is able to mount a response that is appropriate to the danger. Toll-like receptors are at the heart of this pattern recognition system that initiates innate pro-oxidant, pro-inflammatory signaling cascades and ultimately bridges recognition of danger to adaptive immunity. The acute inflammatory lesions that are formed segue into resolution of inflammation, repair and healing or, more dysfunctionally, into chronic inflammation, autoimmunity, excessive tissue damage and carcinogenesis. Redox is at the nexus of this decision making process and is the point at which ionizing radiation initially intercepts to trigger similar responses to self-damage. In this review we discuss our current understanding of how radiation-damaged cells interact with Toll-like receptors and how the immune systems interprets these radiation-induced danger signals in the context of whole-body exposures and during local tumor irradiation. PMID:25819030

  11. Understanding Radiation Thermometry. Part I

    NASA Technical Reports Server (NTRS)

    Risch Timothy K.

    2015-01-01

    This document is a two-part course on the theory and practice of radiation thermometry. Radiation thermometry is the technique for determining the temperature of a surface or a volume by measuring the electromagnetic radiation it emits. This course covers the theory and practice of radiative thermometry and emphasizes the modern application of the field using commercially available electronic detectors and optical components. The course covers the historical development of the field, the fundamental physics of radiative surfaces, along with modern measurement methods and equipment.

  12. Understanding Radiation Thermometry. Part II

    NASA Technical Reports Server (NTRS)

    Risch, Timothy K.

    2015-01-01

    This document is a two-part course on the theory and practice of radiation thermometry. Radiation thermometry is the technique for determining the temperature of a surface or a volume by measuring the electromagnetic radiation it emits. This course covers the theory and practice of radiative thermometry and emphasizes the modern application of the field using commercially available electronic detectors and optical components. The course covers the historical development of the field, the fundamental physics of radiative surfaces, along with modern measurement methods and equipment.

  13. Josephson-vortex Cherenkov radiation

    SciTech Connect

    Mints, R.G.; Snapiro, I.B.

    1995-10-01

    We predict the Josephson-vortex Cherenkov radiation of an electromagnetic wave. We treat a long one-dimensional Josephson junction. We consider the wavelength of the radiated electromagnetic wave to be much less than the Josephson penetration depth. We use for calculations the nonlocal Josephson electrodynamics. We find the expression for the radiated power and for the radiation friction force acting on a Josephson vortex and arising due to the Cherenkov radiation. We calculate the relation between the density of the bias current and the Josephson vortex velocity.

  14. Radiative interactions in nonequilibrium flows

    NASA Technical Reports Server (NTRS)

    Tiwari, S. N.; Chandrasekhar, R.

    1992-01-01

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

  15. Some analytical models of radiating collapsing spheres

    SciTech Connect

    Herrera, L.; Di Prisco, A; Ospino, J.

    2006-08-15

    We present some analytical solutions to the Einstein equations, describing radiating collapsing spheres in the diffusion approximation. Solutions allow for modeling physical reasonable situations. The temperature is calculated for each solution, using a hyperbolic transport equation, which permits to exhibit the influence of relaxational effects on the dynamics of the system.

  16. Radiation induced cognitive impairment and altered diffusion tensor imaging in a juvenile rat model of cranial radiotherapy

    PubMed Central

    Peiffer, Ann M.; Creer, Rebecca M.; Linville, Constance; Olson, John; Kulkarni, Praveen; Brown, Jacquelyn Ann; Riddle, David R.; Robbins, Mike E.; Brunso-Bechtold, Judy E.

    2014-01-01

    Purpose Assess the long term effects of fractionated whole brain irradiation (fWBI) using diffusion tensor imaging (DTI) and behavior in a pediatric rodent model for the clinical presentation of adult pediatric cancer survivors. Materials and Methods Five week old, male F344xBN rats were randomized to receive 0, 5, or 6.5 Gy fractions biweekly for 3 weeks, resulting in Sham, Irradiated-30 (IR-30) and IR-39 Gy total dose groups. Magnetic Resonance Imaging occurred at 1, 3, 6 and 9 months with behavioral assessment at 10–11 months post-fWBI. Results Irradiation reduced brain size (p<0.001) and body weight (p<0.001) proportionate to dose. At 1 month post-fWBI and throughout follow-up, diffusion was reduced in IR-30 and IR-39 relative to shams (p<0.001). IR-30 but not IR-39 rats were impaired relative to Shams on the reversal trial of the Morris Water Maze (p<0.05), and IR-30 rats preferred a striatum-mediated strategy (p<0.06). Conclusions Hippocampal performance was impaired in IR-30 but not IR-39 animals. While gross size differences exist, white matter integrity is preserved in rats after fWBI at 5 weeks. This significant departure from childhood cancer survivors and single fraction rodent studies where white matter degradation is a prominent feature are discussed. PMID:24991879

  17. Radiation-Dominated Disks Are Thermally Stable

    E-print Network

    Shigenobu Hirose; Julian H. Krolik; Omer Blaes

    2008-09-10

    When the accretion rate is more than a small fraction of Eddington, the inner regions of accretion disks around black holes are expected to be radiation-dominated. However, in the alpha-model, these regions are also expected to be thermally unstable. In this paper, we report two 3-d radiation MHD simulations of a vertically-stratified shearing box in which the ratio of radiation to gas pressure is ~ 10, and yet no thermal runaway occurs over a timespan ~ 40 cooling times. Where the time-averaged dissipation rate is greater than the critical dissipation rate that creates hydrostatic equilibrium by diffusive radiation flux, the time-averaged radiation flux is held to the critical value, with the excess dissipated energy transported by radiative advection. Although the stress and total pressure are well-correlated as predicted by the alpha-model, we show that stress fluctuations precede pressure fluctuations, contrary to the usual supposition that the pressure controls the saturation level of the magnetic energy. This fact explains the thermal stability. Using a simple toy-model, we show that independently-generated magnetic fluctuations can drive radiation pressure fluctuations, creating a correlation between the two while maintaining thermal stability.

  18. Optical radiation and visual health

    SciTech Connect

    Waxler, M.; Hitchins, V.M.

    1986-01-01

    This book provides a focus on the parameters of ultraviolet light, visible, and infrared radiation s which could cause long-term visual health problems in humans. It reviews early research on radiation effects on the eye, and gives detailed attention to the hazardous effects of optical radiation on the retinal pigment epithelium and the photoreceptors. These data are further analyzed with regard to five potential long-term visual health problems; retinal degeneration, visual aging, disorder of visual development, ocular drug phototoxicity, and cataracts. Finally, epidemiologic principles for studying the relationships between optical radiation and long-term visual health problems are reviewed, concluding with the implications for future research and radiation protection. The contents include: historical perspectives; optical radiation and cataracts; the involvement of the retinal pigment epithelium (RPE); optical radiation damage to the ocular photoreceptors; possible role of optical radiation in retinal degenerations; optical radiation and the aged eye; optical radiation effects on aging and visual perception; optical radiation effects on visual development; and index.

  19. New Approaches to Radiation Protection

    PubMed Central

    Rosen, Eliot M.; Day, Regina; Singh, Vijay K.

    2015-01-01

    Radioprotectors are compounds that protect against radiation injury when given prior to radiation exposure. Mitigators can protect against radiation injury when given after exposure but before symptoms appear. Radioprotectors and mitigators can potentially improve the outcomes of radiotherapy for cancer treatment by allowing higher doses of radiation and/or reduced damage to normal tissues. Such compounds can also potentially counteract the effects of accidental exposure to radiation or deliberate exposure (e.g., nuclear reactor meltdown, dirty bomb, or nuclear bomb explosion); hence they are called radiation countermeasures. Here, we will review the general principles of radiation injury and protection and describe selected examples of radioprotectors/mitigators ranging from small-molecules to proteins to cell-based treatments. We will emphasize agents that are in more advanced stages of development. PMID:25653923

  20. Method for microbeam radiation therapy

    DOEpatents

    Slatkin, Daniel N. (Sound Beach, NY); Dilmanian, F. Avraham (Yaphank, NY); Spanne, Per O. (Shoreham, NY)

    1994-01-01

    A method of performing radiation therapy on a patient, involving exposing a target, usually a tumor, to a therapeutic dose of high energy electromagnetic radiation, preferably X-ray radiation, in the form of at least two non-overlapping microbeams of radiation, each microbeam having a width of less than about 1 millimeter. Target tissue exposed to the microbeams receives a radiation dose during the exposure that exceeds the maximum dose that such tissue can survive. Non-target tissue between the microbeams receives a dose of radiation below the threshold amount of radiation that can be survived by the tissue, and thereby permits the non-target tissue to regenerate. The microbeams may be directed at the target from one direction, or from more than one direction in which case the microbeams overlap within the target tissue enhancing the lethal effect of the irradiation while sparing the surrounding healthy tissue.