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1

Diffuse radiation  

NASA Technical Reports Server (NTRS)

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.

1981-01-01

2

Adaptive multigroup radiation diffusion  

E-print Network

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 ...

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

2005-01-01

3

Diffuse gamma radiation  

NASA Technical Reports Server (NTRS)

An examination of the intensity, energy spectrum, and spatial distribution of the diffuse gamma-radiation observed by SAS-2 satellite away from the galactic plane in the energy range above 35 MeV has shown that it consists of two components. One component is generally correlated with galactic latitudes, the atomic hydrogen column density was deduced from 21 cm measurements, and the continuum radio emission, believed to be synchrotron emission. It has an energy spectrum similar to that in the plane and joins smoothly to the intense radiation from the plane. It is therefore presumed to be of galactic origin. The other component is apparently isotropic, at least on a coarse scale, and has a steep energy spectrum. No evidence is found for a cosmic ray halo surrounding the galaxy in the shape of a sphere or oblate spheroid with galactic dimensions. Constraints for a halo model with significantly larger dimensions are set on the basis of an upper limit to the gamma-ray anisotropy.

Fichtel, C. E.; Simpson, G. A.; Thompson, D. J.

1977-01-01

4

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,

5

Assessment of diffuse radiation models in Azores  

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

6

A radiating shock evaluated using Implicit Monte Carlo Diffusion  

SciTech Connect

Implicit Monte Carlo [1] (IMC) has been shown to be very expensive when used to evaluate a radiation field in opaque media. Implicit Monte Carlo Diffusion (IMD) [2], which evaluates a spatial discretized diffusion equation using a Monte Carlo algorithm, can be used to reduce the cost of evaluating the radiation field in opaque media [2]. This work couples IMD to the hydrodynamics equations to evaluate opaque diffusive radiating shocks. The Lowrie semi-analytic diffusive radiating shock benchmark[a] is used to verify our implementation of the coupled system of equations. (authors)

Cleveland, M.; Gentile, N. [Lawrence Livermore National Laboratory, P. O. Box 808, Livermore CA 94550 (United States)

2013-07-01

7

Modelling thermal radiation in buoyant turbulent diffusion flames  

Microsoft Academic Search

This work focuses on the numerical modelling of radiative heat transfer in laboratory-scale buoyant turbulent diffusion flames. Spectral gas and soot radiation is modelled by using the Full-Spectrum Correlated-k (FSCK) method. Turbulence-Radiation Interactions (TRI) are taken into account by considering the Optically-Thin Fluctuation Approximation (OTFA), the resulting time-averaged Radiative Transfer Equation (RTE) being solved by the Finite Volume Method (FVM).

J. L. Consalvi; R. Demarco; A. Fuentes

2012-01-01

8

Correlation of total, diffuse, and direct solar radiation  

NASA Technical Reports Server (NTRS)

Present requirements for realistic solar energy system evaluations necessitate a comprehensive body of solar-radition data. The data should include both diffuse and direct solar radiation as well as their total on an hourly (or shorter) basis. In general, however, only the total solar radiation values were recorded. This report presents a correlation that relates the diffuse component of an hourly total solar radiation value to the total radiation ratio of the maximum value attainable. The data used were taken at the Blue Hill Observatory in Milton, Massachusetts, for the period 1952. The relation - in the form of the data plots - can be used in situations in which only the hourly total radiation data are available but the diffuse component is desired.

Buyco, E. H.; Namkoong, D.

1977-01-01

9

Discrete diffusion Monte Carlo for frequency-dependent radiative transfer  

SciTech Connect

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.

Densmore, Jeffrey D [Los Alamos National Laboratory; Kelly, Thompson G [Los Alamos National Laboratory; Urbatish, Todd J [Los Alamos National Laboratory

2010-11-17

10

Diffuse solar radiation and associated meteorological parameters in India  

NASA Astrophysics Data System (ADS)

Solar diffuse radiation data including global radiation, shortwave and longwave balances, net radiation and sunshine hours have been extensively analyzed to study the variation of diffuse radiation with turbidity and cloud discharges appearing in the form of atmospherics over the tropics. Results of surface radiation measurements at Calcutta, Poona, Delhi and Madras are presented together with some meteorological parameters. The monthly values of diffuse radiation and the monthly ratios of diffuse to global solar radiation have been examined, with a special emphasis in relation to the noise level of atmospherics at Calcutta in the very low frequency band. The results exhibit some definite seasonal changes which appear to be in close agreement with one another. Acknowledgements. We gratefully appreciate the on-line DMSP database facility at APL (Newell et al., 1991) from which this study has benefited greatly. We wish to thank E. Friis-Christensen for his encouragement and useful discussions. A. Y. would like to thank the Danish Meteorological Institute, where this work was done, for its hospitality during his stay there and the Nordic Baltic Scholarship Scheme for its financial support of this stay. Topical Editor K.-H. Glassmeier thanks M. J. Engebretson and H. Lühr for their help in evaluating this paper.--> Correspondence to: A. Yahnin-->

Bhattacharya, A. B.; Kar, S. K.; Bhattacharya, R.

1996-10-01

11

Diffusive synchrotron radiation from extragalactic jets  

Microsoft Academic Search

Flattenings of nonthermal radiation spectra observed from knots and interknot\\u000alocations of the jets of 3C273 and M87 in UV and X-ray bands are discussed\\u000awithin modern models of magnetic field generation in the relativistic jets.\\u000aSpecifically, we explicitly take into account the effect of the small-scale\\u000arandom magnetic field, probably present in such jets, which gives rise to\\u000aemission

Gregory D. Fleishman

2005-01-01

12

DIFFUSION OF PROTONS IN THE OUTER RADIATION BELT  

Microsoft Academic Search

The diffusion of protons in the outer radiation belt due to violation of the third adiabatic invariant has been examined. The particular mechanism studied is one in which variations in the intensity of the solar wind produce magnetic disturbances causing motion of particles between L shells. A Fokker-Planck diffusion equation is used with terms describing Coulomb energy degradation and charge-exchange

M. P. Nakada; G. D. Mead

1965-01-01

13

Radiative extinction of gaseous spherical diffusion flames in microgravity  

Microsoft Academic Search

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

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

2007-01-01

14

Radiative Extinction of Gaseous Spherical Diffusion Flames in Microgravity  

NASA Technical Reports Server (NTRS)

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.

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

2007-01-01

15

Diffuse conditions for efficient solution of multislab radiation transport problems  

NASA Astrophysics Data System (ADS)

In this article, we make use of recently developed spectral nodal methods for anisotropically scattering media and we derive mathematical conditions for the diffuse reflection and transmission of radiation in the discrete ordinates formulation of particle transport theory for plane-parallel applications. The conditions arise from a suitable reformulation of spatially discretized equations defined on the boundary layers of a multislab domain. As a result, the boundary layers can be removed from the radiation transport calculations and replaced with exact and numerically stable equivalent conditions. In order to illustrate the applicability and computational merit of our discrete ordinates conditions for diffuse reflection and transmission in radiation transport calculations, we perform numerical experiments with atmospheric radiative transfer and nuclear reactor core models.

de Abreu, Marcos Pimenta

2008-09-01

16

Theoretical and Numerical Investigation of Radiative Extinction of Diffusion Flames  

NASA Technical Reports Server (NTRS)

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.

Ray, Anjan

1996-01-01

17

Radiation singularities, multiple scattering and diffusion in multifractal clouds  

SciTech Connect

Many geophysical and atmospheric fields exhibit multifractal characteristics over wide ranges of scale. These findings motivate a study of transport phenomena in multifractal media, particularly diffusion. As we study the diffusion properties of one-dimensional universal multifractal resistivity fields, a relation for the diffusion exponent d(sub w) is derived and is found to depend only on K(-1), the value of the moment scaling function K(q) of the resistivity field for the q = -1 order statistical moment. This relation is subsequently verified through Monte Carlo simulations of diffusion on these systems. The study of radiative transfer in multifractal clouds is of great interest, an important application being to global climate models. In this work, we develop a formalism analogous to the multifractal singularity formalism for understanding photon scattering statistics in radiative transfer in lognormal universal multifractals, and test the results numerically.

Silas, P.; Broesamlen, G.; Lovejoy, S. [McGill Univ., Quebec (Canada); Naud, C.; Schertzer, D. [Universite Pierre and Marie Curie, Paris (France); Watson, B. [St. Lawrence Univ., Canton, NY (United States)

1995-04-01

18

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

NASA Technical Reports Server (NTRS)

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.

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

1976-01-01

19

Relationship between diffuse, total, and extraterrestrial solar radiation  

Microsoft Academic Search

A method of approximating diffuse beam solar radiation is extended to the upper middle latitudes through the use of several years of mean monthly data and one year of daily data recorded at four stations in Canada which represent a variety of climatic regions as well as both highly urbanized and remote localities. (WDM)

S TULLER

1976-01-01

20

Diffuse conditions for efficient solution of multislab radiation transport problems  

Microsoft Academic Search

In this article, we make use of recently developed spectral nodal methods for anisotropically scattering media and we derive mathematical conditions for the diffuse reflection and transmission of radiation in the discrete ordinates formulation of particle transport theory for plane-parallel applications. The conditions arise from a suitable reformulation of spatially discretized equations defined on the boundary layers of a multislab

Marcos Pimenta de Abreu

2008-01-01

21

Radiation hydrodynamics of triggered star formation: the effect of the diffuse radiation field  

NASA Astrophysics Data System (ADS)

We investigate the effect of including diffuse field radiation when modelling the radiatively driven implosion of a Bonnor-Ebert sphere (BES). Radiation-hydrodynamical calculations are performed by using operator splitting to combine Monte Carlo photoionization with grid-based Eulerian hydrodynamics that includes self-gravity. It is found that the diffuse field has a significant effect on the nature of radiatively driven collapse which is strongly coupled to the strength of the driving shock that is established before impacting the BES. This can result in either slower or more rapid star formation than expected using the on-the-spot approximation depending on the distance of the BES from the source object. As well as directly compressing the BES, stronger shocks increase the thickness and density in the shell of accumulated material, which leads to short, strong, photoevaporative ejections that reinforce the compression whenever it slows. This happens particularly effectively when the diffuse field is included as rocket motion is induced over a larger area of the shell surface. The formation and evolution of 'elephant trunks' via instability is also found to vary significantly when the diffuse field is included. Since the perturbations that seed instabilities are smeared out elephant trunks form less readily and, once formed, are exposed to enhanced thermal compression.

Haworth, Thomas J.; Harries, Tim J.

2012-02-01

22

Pulsar and diffuse contributions to the observed galactic gamma radiation  

NASA Technical Reports Server (NTRS)

With the acquisition of satellite data on the energy spectrum of galactic gamma-radiation, it is clear that such radiation has a multicomponent nature. A calculation of the pulsar gamma ray emission spectrum is used together with a statistical analysis of recent data on 328 known pulsars to make a new determination of the pulsar contribution to galactic gamma ray emission. The contributions from diffuse interstellar cosmic ray induced production mechanisms to the total emission are then reexamined. It is concluded that pulsars may account for a significant fraction of galactic gamma ray emission.

Harding, A. K.; Stecker, F. W.

1980-01-01

23

Pulsar and diffuse contributions to the observed galactic gamma radiation  

SciTech Connect

With the acquisition of satellite data on the energy spectrum of galactic gamma-radiation, it is clear that such radiation has a multicomponent nature. A calculation of the pulsar gamma ray emission spectrum is used together with a statistical analysis of recent data on 328 known pulsars to make a new determination of the pulsar contribution to galactic gamma ray emission. The contributions from diffuse interstellar cosmic ray induced production mechanisms to the total emission are then reexamined. It is concluded that pulsars may account for a significant fraction of galactic gamma ray emission.

Harding, A.K.; Stecker, F.W.

1980-10-01

24

Observations of diffuse galactic gamma radiation  

SciTech Connect

A new window for studying our Galaxy has emerged after over two decases of concerted effort with satellite and balloon-borne gammay-ray experiments. These experiments have discovered what appears to be a diffuse glow along the Galactic plane in lines at 0.511 and 1.809 MeV. I summarize these observations, with emphasis on measurements made with the Gamma-Ray Spectrometer (GRS) on NASA's Solar Maximum Mission satellite (SMM). The GRS is currently being used to study other diffuse Galactic emissions including the positronium continuum, radioactive lines from recent supernovae and novae, and de-excitation lines from interactions of cosmic-ray protons with interstellar carbon and oxygen.

Share, G.H.

1988-09-25

25

The origin of the diffuse background gamma radiation  

NASA Technical Reports Server (NTRS)

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.

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

1974-01-01

26

The Mystery of the Cosmic Diffuse Ultraviolet Background Radiation  

NASA Astrophysics Data System (ADS)

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.

Conn Henry, Richard; Murthy, Jayant; Overduin, James; Tyler, Joshua

2015-01-01

27

VOYAGER OBSERVATIONS OF THE DIFFUSE FAR-ULTRAVIOLET RADIATION FIELD  

SciTech Connect

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.

Murthy, Jayant [Indian Institute of Astrophysics, Bengalooru 560 034 (India); Henry, Richard Conn [Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218 (United States); Holberg, Jay B., E-mail: jmurthy@yahoo.com [Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721 (United States)

2012-03-01

28

Wireless in-house data communication via diffuse infrared radiation  

Microsoft Academic Search

A novel wireless broadcast\\/multi-access channel is described for flexibly interconnecting a cluster of data terminals located within the same room. The transmission medium is diffusively scattered infrared radiation at 950-nm wavelength. Transmission is low-to-medium speed and the range up to 50 m. Theoretical analysis indicates that the time dispersion limits the transmission bandwidth of the system to 260 Mbit ?

FRITZ R. GFELLER; URS BAPST

1979-01-01

29

Influence of radiation damage on xenon diffusion in silicon carbide  

NASA Astrophysics Data System (ADS)

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.

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

2014-08-01

30

Radiation Hydrodynamics  

NASA Astrophysics Data System (ADS)

Basic Radiation Theory Specific Intensity Photon Number Density Photon Distribution Function Mean Intensity Radiation Energy Density Radiation Energy Flux Radiation Momentum Density Radiation Stress Tensor (Radiation Pressure Tensor) Thermal Radiation Thermodynamics of Thermal Radiation and a Perfect Gas The Transfer Equation Absorption, Emission, and Scattering The Equation of Transfer Moments of the Transfer Equation Lorentz Transformation of the Transfer Equation Lorentz Transformation of the Photon 4-Momentum Lorentz Transformation of the Specific Intensity, Opacity, and - Emissivity Lorentz Transformation of the Radiation Stress Energy Tensor The Radiation 4-Force Density Vector Covariant Form of the Transfer Equation Inertial-Frame Equations of Radiation Hydrodynamics Inertial-Frame Radiation Equations Inertial-Frame Equations of Radiation Hydrodynamics Comoving-Frame Equation of Transfer Special Relativistic Derivation (D. Mihalas) Consistency Between Comoving-Frame and Inertial-Frame Equations Noninertial Frame Derivation (J. I. Castor) Analysis of O (v/c) Terms Lagrangian Equations of Radiation Hydrodynamics Momentum Equation Gas Energy Equation First Law of Thermodynamics for the Radiation Field First Law of Thermodynamics for the Radiating Fluid Mechanical Energy Equation Total Energy Equation Consistency of Different Forms of the Radiating-Fluid Energy - and Momentum Equations Consistency of Inertial-Frame and Comoving-Frame Radiation Energy - and Momentum Equations Radiation Diffusion Radiation Diffusion Nonequilibrium Diffusion The Problem of Flux Limiting Shock Propagation: Numerical Methods Acoustic Waves Numerical Stability Systems of Equations Implications of Shock Development Implications of Diffusive Energy Transport Illustrative Example Numerical Radiation Hydrodynamics Radiating Fluid Energy and Momentum Equations Computational Strategy Energy Conservation Formal Solution Multigroup Equations An Astrophysical Example Adaptive-Grid Radiation Hydrodynamics Front Fitting Artificial Dissipation The Adaptive Grid The TITAN Code References

Mihalas, Dimitri

31

The Gamma-ray galactic diffuse radiation and Cerenkov telescopes  

SciTech Connect

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.}

Chardonnet, P. [Theoretical Physics Group ENSLAPP, BP110, F-74941 Annecy-le-Vieux Cedex (France)] [Theoretical Physics Group ENSLAPP, BP110, F-74941 Annecy-le-Vieux Cedex (France); [Universite de Savoie, BP1104, 73011 Chambery Cedex (France); Salati, P. [Theoretical Physics Group ENSLAPP, BP110, F-74941 Annecy-le-Vieux Cedex (France)] [Theoretical Physics Group ENSLAPP, BP110, F-74941 Annecy-le-Vieux Cedex (France); [Universite de Savoie, BP1104, 73011 Chambery Cedex (France); [Institut Universitaire de France; Silk, J. [545 Campbell Hall, Astronomy Department, University of California at Berkeley, Berkeley, California 94720 (United States)] [545 Campbell Hall, Astronomy Department, University of California at Berkeley, Berkeley, California 94720 (United States); Grenier, I. [Departement dAstrophysique, Centre dEtudes Nucleaires de Saclay, F-91191 Gif-sur-Yvette Cedex (France)] [Departement dAstrophysique, Centre dEtudes Nucleaires de Saclay, F-91191 Gif-sur-Yvette Cedex (France); Smoot, G. [Building 50, Room 205, Lawrence Berkeley Laboratory, 1 Cyclotron Road, Berkeley, California 94720 (United States)] [Building 50, Room 205, Lawrence Berkeley Laboratory, 1 Cyclotron Road, Berkeley, California 94720 (United States)

1995-12-01

32

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

E-print Network

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

Goudon, Thierry

33

Optimization of efficiency and response time of diffusion-based nuclear radiation detectors  

Microsoft Academic Search

The charge collection process in a diffusion-based silicon nuclear radiation detector was investigated by illuminating the detector at the backside with optical radiation. The results are compared to calculations and show good agreement. The collection mechanism is characterized, and the detector response to nuclear radiation and its optimum with respect to efficiency and response time are calculated. Efficiency and response

S. E. Wouters; T. Otaredian; E. M. Schooneveld

1991-01-01

34

Newton-Krylov methods applied to nonequilibrium radiation diffusion  

SciTech Connect

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.

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

1998-03-10

35

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

NASA Astrophysics Data System (ADS)

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.

Obara, Shin'ya

36

An anisotropic model of diffuse solar radiation with application to an optimization of compound parabolic collectors  

Microsoft Academic Search

Based on a simple geometrical description of the sky hemisphere and the magnitude of the horizontal diffuse radiation, a model for estimating diffuse radiation impinging on sloping surfaces was developed. Tests against data show that substantial improvement is achieved over the classical isotropic model for any collector slope or orientation. Improvement is found for instantaneous as well as accumulated data.

R. R. Perez

1983-01-01

37

Estimation of Diffuse Fraction of Global Solar Radiation Using Artificial Neural Networks  

Microsoft Academic Search

Measured daily mean air temperature and relative humidity values between 1998 and 2002 for Abha city in Saudi Arabia were used for predicting diffuse fraction of solar radiation in future time domain using artificial neural networks method. The estimations of diffuse solar radiation were made using four combinations of data sets, viz. (i) day of the year and daily maximum

S. Rehman; M. Mohandes

2009-01-01

38

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

NASA Technical Reports Server (NTRS)

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.

Plante, Ianik; Cucinotta, Francis A.

2011-01-01

39

On equivalent diffuse conditions for an internal layer in multislab atmospheric radiation  

NASA Astrophysics Data System (ADS)

This paper reports on new discrete ordinates conditions for efficiently solving a set of multislab atmospheric radiation problems characterized by an optically stationary internal layer, i.e. an internal layer whose optical (absorption/scattering) properties and optical thickness do not change from one problem to another in the set. The discrete ordinates conditions reported here are founded in a recently developed spectral nodal method for solving multislab atmospheric radiation problems with anisotropic scattering. We suitably use the optically discretized equations of our recently developed spectral nodal method to derive discrete ordinates diffuse conditions, which model the response—diffuse radiation leaving the layer—of an internal layer to an anisotropic inner source and to diffuse radiation that is incident upon the layer at top and bottom. These conditions can be used to replace an optically stationary internal layer in multislab atmospheric radiation computations, while saving computer resources and without degrading the numerical results.

de Abreu, Marcos Pimenta

2006-12-01

40

Investigation of the radiative properties of chain agglomerated soot formed in hydrocarbon diffusion flames  

Microsoft Academic Search

An investigation into the radiative scattering and extinction properties of chain-agglomerated soot particles, formed in hydrocarbon diffusion flames, has been conducted. Several different theoretical approximations of the agglomerate radiative behavior were examined. Based upon these approximations, the radiative properties of chain-agglomerates can show significant departure from those produced by spherically-shaped particles. For the visible and infrared wavelengths, a significant difference

Mackowski

1987-01-01

41

Pollutant emission and noise radiation from open and impinging inverse diffusion flames  

Microsoft Academic Search

â–º The effect of burner geometry (dair and S) on inverse diffusion flames is studied. â–º With fixed air\\/fuel supplies, a smaller dair curtails NOx emission but augments noise radiation. â–º With fixed air\\/fuel supplies, a larger S reduces NOx emission but increases noise radiation. â–º Both NOx emission and noise radiation are maximum under stoichiometric combustion. â–º Impinging flames

Y. S. Choy; H. S. Zhen; C. W. Leung; H. B. Li

2012-01-01

42

Combustion and radiation characteristics of oxygen-enhanced inverse diffusion flame  

Microsoft Academic Search

The characteristics of combustion and radiation heat transfer of an oxygen-enhanced diffusion flame was experimentally analyzed.\\u000a An infrared radiation heat flux gauge was used to measure the thermal radiation of various types of flames with fuel, air\\u000a and pure oxygen. And the Laser Induced Incandescence (LII) technique was applied to characterize the soot concentrations which\\u000a mainly contribute to the continuum

Sang Soon Hwang; Jay P Gore

2002-01-01

43

An Improved Multipyranometer Array for the Measurement of Direct and Diffuse Solar Radiation  

E-print Network

This paper describes an improved multipyranometer array (MPA) for the continuous remote measurement of direct and diffuse solar radiation. The MPA described in this paper is an improvement over previously published MPA studies due...

Munger, B.; Haberl, J. S.

1994-01-01

44

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

SciTech Connect

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.

Winske, Dan [Los Alamos National Laboratory

2012-07-16

45

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

NASA Astrophysics Data System (ADS)

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.

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

2014-10-01

46

Diffuse radiation increases global ecosystem-level water-use efficiency  

NASA Astrophysics Data System (ADS)

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.

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

2012-12-01

47

Spectral radiative effects and turbulence\\/radiation interaction in a non-luminous turbulent jet diffusion flame  

Microsoft Academic Search

A non-luminous turbulent jet diffusion flame is numerically simulated using a Reynolds stress second-order closure, the steady laminar flamelet model, and different approaches for radiative transfer. The commonly used optically thin approximation is compared with the discrete ordinates method. Calculations using the Planck mean absorption coefficient are compared with computations performed using the spectral line-based weighted-sum-of-gray-gases model. The interaction between

P. J. Coelho; O. J. Teerling; D. Roekaerts

2003-01-01

48

The influence of natural radiation damage on helium diffusion kinetics in apatite  

E-print Network

The influence of natural radiation damage on helium diffusion kinetics in apatite David L. Shuster diffusion experiments on 39 different apatite samples using radiogenic 4 He and proton-induced 3 He reveal] is a proxy for a sample's natural exposure to actinide radioactivity below the closure temperature

Shuster, David L.

49

Comparison of Radiative Transport, Monte Carlo, and Diffusion Forward Models for Small Animal Optical Tomography  

Microsoft Academic Search

Herein we present a comparison of Monte Carlo, radiative transport (RT), and diffusion based forward models for implementation into small animal optical tomography algorithm. The simulations show that the unique RT solver can accurately predict the time-dependent propagation of excitation and emission photons in diffuse as well as transport limited systems. Furthermore, the need for the accurate modeling of incident

John C. Rasmussen; Tianshu Pan; Amit Joshi; Todd A. Wareing; John Mcghee; Eva M. Sevick-muraca

2007-01-01

50

Investigation of radiation diffusion in a thin Au wall using x-ray backlit imaging  

NASA Astrophysics Data System (ADS)

Radiation diffusion occurs in the hohlraum wall in Inertial Confinement Fusion (ICF). ICF hohlraums come in both thick and thin wall versions. The thick wall hohlraum contains the laser produced drive radiation efficiently, but precludes direct observation of the laser-wall interaction region The thin wall hohlraum (TWH) allows an x-ray image of the interaction region to be observed through the wall, with minimal impact on the hohlraum energetics. The TWH typically consists of a 2-3 um Au layer surrounded by a supporting wall of plastic or Al. Energy loss by diffusion through the thin Au layer can have a significant impact on the energetics of the hohlraum, but the losses have never been directly examined. The present work examines the radiation diffusion through a 1 um Au wall with a 25 um Al support layer by imaging the expansion of the Al under the influence of the radiation diffusing through the Au layer. 6.7 keV x-ray backlit imaging is used to examine the outer Al surface location as a function of time, and to compare the resultant trajectory to that predicted by a radiation hydrodynamics code. The experiments are done on the Sandia National Laboratories Z accelerator, using the dynamic hohlraum as a radiation source to drive the expansion of a small TWH. Images and simulations will be compared.

Watt, R. G.; Chrien, R. E.; Idzorek, G.

2003-10-01

51

Measure of Diffusion Model Error for Thermal Radiation Transport  

E-print Network

1;R 1 2 p 3 Ti;L T i 1;R : (9.3e) Assuming i = T i ; (9.4a) i 12 = ~ Ti 12 (9.4b) we observe that (9.2) simpli es to Fi;L=R = F T i;L=R: (9.5) Substituting (9.5) into (9.1), we observe that i;L=R = T i;L=R: (9.6... Nested Iteration Method : : : : : : : : : : : : : : : : : : : : : 23 7.4 Discrete Radiative Transfer Equations : : : : : : : : : : : : : : : : : 24 7.5 S2 Synthetic Acceleration (S2SA) : : : : : : : : : : : : : : : : : : : : 25 7.6 S2 Multi Frequency...

Kumar, Akansha

2013-04-19

52

Asymptotic equilibrium diffusion analysis of time-dependent Monte Carlo methods for grey radiative transfer  

Microsoft Academic Search

The equations of nonlinear, time-dependent radiative transfer are known to yield the equilibrium diffusion equation as the leading-order solution of an asymptotic analysis when the mean-free path and mean-free time of a photon become small. We apply this same analysis to the Fleck-Cummings, Carter-Forest, and N'kaoua Monte Carlo approximations for grey (frequency-independent) radiative transfer. Although Monte Carlo simulation usually does

Jeffery D. Densmore; Edward W. Larsen

2004-01-01

53

Asymptotic equilibrium diffusion analysis of time-dependent Monte Carlo methods for grey radiative transfer  

Microsoft Academic Search

The equations of nonlinear, time-dependent radiative transfer are known to yield the equilibrium diffusion equation as the leading-order solution of an asymptotic analysis when the mean-free path and mean-free time of a photon become small. We apply this same analysis to the Fleck–Cummings, Carter–Forest, and N'kaoua Monte Carlo approximations for grey (frequency-independent) radiative transfer. Although Monte Carlo simulation usually does

Jeffery D. Densmore; Edward W. Larsen

2004-01-01

54

PITCH-ANGLE DIFFUSION OF RADIATION-BELT ELECTRONS WITHIN THE PLASMASPHERE  

Microsoft Academic Search

The goal of this work is to explain the formation of the quiet-time electron slot, which divides the radiation belt electrons into an inner and an outer zone. We quantitatively investigate the pitch-angle diffusion of radiation belt electrons resulting from resonant interactions with the observed plasmaspheric whistler-mode wave band. The effects of wave propagation obliquely to the geomagnetic field direction

Lawrence R. Lyons; Richard Mansergh Thorne; Charles F. Kennel

1972-01-01

55

Analysis of radiative transfer within arbitrary 3-D isotropically scattering medium enclosed by diffuse surfaces  

NASA Astrophysics Data System (ADS)

The exact integral expressions are presented for radiative transfer in an arbitrary three-dimensional absorbing, emitting, isotropically scattering medium enclosed by diffuse surfaces. This paper also presents a straightforward method, the nodal approximation technique, for solving the numerical results of radiative transfer in a medium of arbitrary geometry. The method is easily applied and would provide solutions in a functional relation. Two sample examples of different type geometries, a one-dimensional concentric cylinder and a two-dimensional rectangular enclosure, are analyzed and compared to the existing results to illustrate the accuracy and applicability of the present method. Results show that the present method can accurately predict the radiation distributions.

Lin, J. D.

1987-01-01

56

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

NASA Astrophysics Data System (ADS)

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.

Asakuma, Yusuke; Miura, Masataka

2014-09-01

57

A study of the diffuse galactic gamma radiation  

NASA Technical Reports Server (NTRS)

Assuming cosmic rays pervade the Galaxy, they necessarily produced high energy gamma-rays as they interact with the instellar matter and photons. The cosmic ray nucleon interactions five rise to gamma rays primarily through the decay of pi mesons, giving a unique spectrum with a maximum at approximately 68 MeV. Cosmic ray electrons produce gamma rays through bremsstrahlung, but with a markedly different energy spectral shape, one which decreases monotonically with energy. Cosmic ray electrons also interact with the interstellar starlight, optical and infrared photons, and the blackbody radiation through the Compton process. A model of galactic gamma ray production is discussed, and the predicted spatial distribution and energy spectra are presented. Considering the uncertainty in the point source contributions, the agreement between the theoretical predictions and the gamma ray data seems quite reasonable.

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

1982-01-01

58

Comparative radiation resistance, temperature dependence and performance of diffused junction indium phosphide solar cells  

NASA Technical Reports Server (NTRS)

Indium phosphide solar cells whose p-n junctions were processed by the open tube capped diffusion and by the closed tube uncapped diffusion of sulfur into Czochralski-grown p-type substrates are compared. Differences found in radiation resistance were attributed to the effects of increased base dopant concentration. Both sets of cells showed superior radiation resistance to that of gallium arsenide cells, in agreement with previous results. No correlation was, however, found between the open-circuit voltage and the temperature dependence of the maximum power.

Weinberg, I.; Swartz, C. K.; Hart, R. E., Jr.; Ghandhi, S. K.; Borrego, J. M.

1987-01-01

59

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 ...

60

An Experimental and Theoretical Study of Radiative Extinction of Diffusion Flames  

NASA Technical Reports Server (NTRS)

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.

Atreya, Arvind

1995-01-01

61

Development of SDE (Stochastic Differential Equation) Methods for Solving Radiation Belt Diffusion Equations  

NASA Astrophysics Data System (ADS)

Drift-resonance interactions with magnetohydrodynamic waves and cyclotron-resonance interactions with whistler-mode chorus waves (as well as other cyclotron-frequency waves) are thought to be important mechanisms for energizing and transporting relativistic electrons in the radiation belts, and these processes are often modeled using quasilinear diffusion equations. In this paper we report on recent efforts to solve radiation belt diffusion equations using stochastic differential equation (SDE) methods. Specifically, we make use of existing mathematical research which shows that radiation belt diffusion equations are equivalent to sets of SDEs and we adopt numerical methods of solving the SDEs to obtain solutions of the corresponding diffusion equation. Solutions of the 2D bounce-averaged energy-pitch-angle diffusion equation for cyclotron-resonance interactions of relativistic electrons with whistler-mode chorus waves will be presented, in which we have investigated the effects of (i) ignoring off-diagonal diffusion terms, and (ii) assuming purely parallel-propagating waves.

Chan, Anthony; Albert, Jay; Tao, Xin

62

An anisotropic model of diffuse solar radiation with application to an optimization of compound parabolic collectors  

NASA Astrophysics Data System (ADS)

Based on a simple geometrical description of the sky hemisphere and the magnitude of the horizontal diffuse radiation, a model for estimating diffuse radiation impinging on sloping surfaces was developed. Tests against data show that substantial improvement is achieved over the classical isotropic model for any collector slope or orientation. Improvement is found for instantaneous as well as accumulated data. The application of the model to compound parabolic collectors (CPC) accounts partly for the role played by forward scattered radiation in the total energy they receive. An optimization of CPC's geometrical characteristics is performed for photovoltaic generation in the area of Albany, NY. This calculation is used to assess the relative effects of meteorological conditions and economic assumptions or optimum concentration values, and provides the reader with information pertaining to the variation of the cost of electrical energy produced as a function of the cost of silicon solar cells.

Perez, R. R.

63

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

NASA Technical Reports Server (NTRS)

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.

Dermer, C. D.

1986-01-01

64

Influence of radiative loss on nitric oxide formation in counterflow diffusion flames at high pressure  

Microsoft Academic Search

A theoretical analysis is given of the effect of nonluminous thermal radiation on the properties of counterflow diffusion flames at high pressure. The self-consistent analysis includes an expression for gas band radiant dissipation in the energy equation of a counterflow flame solver. NO[sub x] formation rates and other properties are studied as a function of strain rate for adiabatic, optically

A. Vranos; R. J. Hall

1993-01-01

65

Radiation pressure of standing waves on liquid columns and small diffusion flames  

NASA Astrophysics Data System (ADS)

The radiation pressure of standing ultrasonic waves in air is demonstrated in this investigation to influence the dynamics of liquid columns and small flames. With the appropriate choice of the acoustic amplitude and wavelength, the natural tendency of long columns to break because of surface tension was suppressed in reduced gravity [M. J. Marr-Lyon, D. B. Thiessen, and P. L. Marston, Phys. Rev. Lett. 86, 2293-2296 (2001); 87(20), 9001(E) (2001)]. Evaluation of the radiation force shows that narrow liquid columns are attracted to velocity antinodes. The response of a small vertical diffusion flame to ultrasonic radiation pressure in a horizontal standing wave was observed in normal gravity. In agreement with our predictions of the distribution of ultrasonic radiation stress on the flame, the flame is attracted to a pressure antinode and becomes slightly elliptical with the major axis in the plane of the antinode. The radiation pressure distribution and the direction of the radiation force follow from the dominance of the dipole scattering for small flames. Understanding radiation stress on flames is relevant to the control of hot fluid objects. [Work supported by NASA.

Thiessen, David B.; Marr-Lyon, Mark J.; Wei, Wei; Marston, Philip L.

2002-11-01

66

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

SciTech Connect

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.

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

67

Solar radiation model  

Microsoft Academic Search

Solar radiation models for predicting the average daily and hourly global radiation, beam radiation and diffuse radiation are reviewed in this paper. Seven models using the Ångström–Prescott equation to predict the average daily global radiation with hours of sunshine are considered. The average daily global radiation for Hong Kong (22.3°N latitude, 114.3°E longitude) is predicted. Estimations of monthly average hourly

L. T. Wong; W. K. Chow

2001-01-01

68

Boundary Conditions for the Diffusion Equation in Radiative Transfer  

Microsoft Academic Search

Using the method of images, we examine the three boundary conditions commonly applied to the surface of a semi-infinite turbid medium. We find that the image-charge configurations of the partial-current and extrapolated-boundary conditions have the same dipole and quadrupole moments and that the two corresponding solutions to the diffusion equation are approximately equal. In the application of diffusion theory to

Richard C. Haskell; Lars O. Svaasand; Tsong-Tseh Tsay; Ti-Chen Feng; Matthew S. McAdams; Bruce J. Tromberg

1994-01-01

69

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

PubMed Central

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

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

2015-01-01

70

Using a simple apparatus to measure direct and diffuse photosynthetically active radiation at remote locations.  

PubMed

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

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

2015-01-01

71

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...

72

Evaluation of a radiative transfer equation and diffusion approximation hybrid forward solver for fluorescence molecular imaging.  

PubMed

The solution of the forward problem in fluorescence molecular imaging strongly influences the successful convergence of the fluorophore reconstruction. The most common approach to meeting this problem has been to apply the diffusion approximation. However, this model is a first-order angular approximation of the radiative transfer equation, and thus is subject to some well-known limitations. This manuscript proposes a methodology that confronts these limitations by applying the radiative transfer equation in spatial regions in which the diffusion approximation gives decreased accuracy. The explicit integro differential equations that formulate this model were solved by applying the Galerkin finite element approximation. The required spatial discretization of the investigated domain was implemented through the Delaunay triangulation, while the azimuthal discretization scheme was used for the angular space. This model has been evaluated on two simulation geometries and the results were compared with results from an independent Monte Carlo method and the radiative transfer equation by calculating the absolute values of the relative errors between these models. The results show that the proposed forward solver can approximate the radiative transfer equation and the Monte Carlo method with better than 95% accuracy, while the accuracy of the diffusion approximation is approximately 10% lower. PMID:23208221

Gorpas, Dimitris; Andersson-Engels, Stefan

2012-12-01

73

Differences in Brainstem Fiber Tract Response to Radiation: A Longitudinal Diffusion Tensor Imaging Study  

SciTech Connect

Purpose: To determine whether radiation-induced changes in white matter tracts are uniform across the brainstem. Methods and Materials: We analyzed serial diffusion tensor imaging data, acquired before radiation therapy and over 48 to 72 months of follow-up, from 42 pediatric patients (age 6-20 years) with medulloblastoma. FSL software (FMRIB, Oxford, UK) was used to calculate fractional anisotropy (FA) and axial, radial, and mean diffusivities. For a consistent identification of volumes of interest (VOIs), the parametric maps of each patient were transformed to a standard brain space (MNI152), on which we identified VOIs including corticospinal tract (CST), medial lemniscus (ML), transverse pontine fiber (TPF), and middle cerebellar peduncle (MCP) at the level of pons. Temporal changes of DTI parameters in VOIs were compared using a linear mixed effect model. Results: Radiation-induced white matter injury was marked by a decline in FA after treatment. The decline was often accompanied by decreased axial diffusivity, increased radial diffusivity, or both. This implied axonal damage and demyelination. We observed that the magnitude of the changes was not always uniform across substructures of the brainstem. Specifically, the changes in DTI parameters for TPF were more pronounced than in other regions (P<.001 for FA) despite similarities in the distribution of dose. We did not find a significant difference among CST, ML, and MCP in these patients (P>.093 for all parameters). Conclusions: Changes in the structural integrity of white matter tracts, assessed by DTI, were not uniform across the brainstem after radiation therapy. These results support a role for tract-based assessment in radiation treatment planning and determination of brainstem tolerance.

Uh, Jinsoo, E-mail: jinsoo.uh@stjude.org [Department of Radiological Sciences, St. Jude Children's Research Hospital, Memphis, Tennessee (United States)] [Department of Radiological Sciences, St. Jude Children's Research Hospital, Memphis, Tennessee (United States); Merchant, Thomas E. [Department of Radiological Sciences, St. Jude Children's Research Hospital, Memphis, Tennessee (United States)] [Department of Radiological Sciences, St. Jude Children's Research Hospital, Memphis, Tennessee (United States); Li, Yimei; Feng, Tianshu [Department of Biostatistics, St. Jude Children's Research Hospital, Memphis, Tennessee (United States)] [Department of Biostatistics, St. Jude Children's Research Hospital, Memphis, Tennessee (United States); Gajjar, Amar [Department of Oncology, St. Jude Children's Research Hospital, Memphis, Tennessee (United States)] [Department of Oncology, St. Jude Children's Research Hospital, Memphis, Tennessee (United States); Ogg, Robert J.; Hua, Chiaho [Department of Radiological Sciences, St. Jude Children's Research Hospital, Memphis, Tennessee (United States)] [Department of Radiological Sciences, St. Jude Children's Research Hospital, Memphis, Tennessee (United States)

2013-06-01

74

An Experimental and Theoretical Study of Radiative Extinction of Diffusion Flames  

NASA Technical Reports Server (NTRS)

In a recent paper on 'Observations of candle flames under various atmospheres in microgravity' by Ross et al., it was found that for the same atmosphere, the burning rate per unit wick surface area and the flame temperature were considerably reduced in microgravity as compared with normal gravity. Also, the flame (spherical in microgravity) was much thicker and further removed from the wick. It thus appears that the flame becomes 'weaker' in microgravity due to the absence of buoyancy generated flow which serves to transport the oxidizer to the combustion zone and remove the hot combustion products from it. The buoyant flow, which may be characterized by the strain rate, assists the diffusion process to execute these essential functions for the survival of the flame. Thus, the diffusion flame is 'weak' at very low strain rates and as the strain rate increases the flame is initially 'strengthened' and eventually it may be 'blown out'. The computed flammability boundaries of T'ien show that such a reversal in material flammability occurs at strain rates around 5 sec. At very low or zero strain rates, flame radiation is expected to considerably affect this 'weak' diffusion flame because: (1) the concentration of combustion products which participate in gas radiation is high in the flame zone; and (2) low strain rates provide sufficient residence time for substantial amounts of soot to form which is usually responsible for a major portion of the radiative heat loss. We anticipate that flame radiation will eventually extinguish this flame. Thus, the objective of this project is to perform an experimental and theoretical investigation of radiation-induced extinction of diffusion flames under microgravity conditions. This is important for spacecraft fire safety.

Atreya, Arvind; Wichman, Indrek; Guenther, Mark; Ray, Anjan; Agrawal, Sanjay

1993-01-01

75

Pulsar and diffuse contributions to observed galactic gamma radiation  

NASA Technical Reports Server (NTRS)

The first calculation of a gamma-ray production spectrum from pulsars in the Galaxy, along with a statistical analysis of data on 328 known radio pulsars, are presented. The implications of this point source contribution to the general interpretation of the observed galactic gamma-ray spectrum are indicated. The contributions from diffuse interstellar cosmic-ray induced production mechanisms are then re-examined, concluding that pulsars may be contributing significantly to the galactic gamma-ray emission.

Harding, A. K.; Stecker, F. W.

1981-01-01

76

Influence of thermal radiation on soot production in Laminar axisymmetric diffusion flames  

NASA Astrophysics Data System (ADS)

The aim of this paper is to study the effect of radiative heat transfer on soot production in laminar axisymmetric diffusion flames. Twenty-four C1-C3 hydrocarbon-air flames, consisting of normal (NDF) and inverse (IDF) diffusion flames at both normal gravity (1 g) and microgravity (0 g), and covering a wide range of conditions affecting radiative heat transfer, were simulated. The numerical model is based on the Steady Laminar Flamelet (SLF) model, a semi-empirical two-equation acetylene/benzene based soot model and the Statistical Narrow Band Correlated K (SNBCK) model coupled to the Finite Volume Method (FVM) to compute thermal radiation. Predictions relative to velocity, temperature, soot volume fraction and radiative losses are on the whole in good agreement with the available experimental data. Model results show that, for all the flames considered, thermal radiation is a crucial process with a view to providing accurate predictions for temperatures and soot concentrations. It becomes increasingly significant from IDFs to NDFs and its influence is much greater as gravity is reduced. The radiative contribution of gas prevails in the weakly-sooting IDFs and in the methane and ethane NDFs, whereas soot radiation dominates in the other flames. However, both contributions are significant in all cases, with the exception of the 1 g IDFs investigated where soot radiation can be ignored. The optically-thin approximation (OTA) was also tested and found to be applicable as long as the optical thickness, based on flame radius and Planck mean absorption coefficient, is less than 0.05. The OTA is reasonable for the IDFs and for most of the 1 g NDFs, but it fails to predict the radiative heat transfer for the 0 g NDFs. The accuracy of radiative-property models was then assessed in the latter cases. Simulations show that the gray approximation can be applied to soot but not to combustion gases. Both the non-gray and gray soot versions of the Full Spectrum Correlated k (FSCK) model can be then substituted for the SNBCK with a reduction in CPU time by a factor of about 20 in the latter case.

Demarco, R.; Nmira, F.; Consalvi, J. L.

2013-05-01

77

Evaluating contextual processing in diffusion MRI: application to optic radiation reconstruction for epilepsy surgery.  

PubMed

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

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

2014-01-01

78

Radial diffusion models of energetic electrons and Jupiter's synchrotron radiation. 2: Time variability  

NASA Astrophysics Data System (ADS)

We used a radial diffusion code for energetic electrons in Jupiter's magnetosphere to investigate variations in Jupiter's radio emission due to changes in the electron phase space density at L shells between 6 and 50, and due to changes in the radial diffusion parameters. We suggest that the observed variations in Jupiter's radio emission are likely caused by changes in the electron phase space density at some boundary L1 is greater than 6, if the primary mode of transport of energetic electrons is radial diffusion driven by fluctuating electric and/or magnetic fields induced by upper atmospheric turbulence. We noticed an excellent empirical correlation, both in phase and relative amplitude, between changes in the solar wind ram pressure and Jupiter's synchrotron radiation if the electron phase space density at the boundary L1 (L1 is approximately equal to 20-50) varies linearly with the square root of the solar wind ram pressure, f is approximately (Nsnu2s)1/2. The calculations were carried out with a diffusion coefficient DLL = DnLn with n = 3. The diffusion coefficient which best fit the observed variations in Jupiter's synchrotron radiation D3 = 1.3 +/- 0.2 x 10-9/s is approximately 0.041/yr, which corresponds to a lagtime of approximately 2 years. We further show that the observed short term (days-weeks) variations in Jupiter's radio emission cannot be explained adequately when radial diffusion is taken into account.

de Pater, I.

1994-02-01

79

Polarization radiation in the planetary atmosphere delimited by a heterogeneous diffusely reflecting surface  

NASA Technical Reports Server (NTRS)

Spatial frequency characteristics (SFC) and the scattering functions were studied in the two cases of a uniform horizontal layer with absolutely black bottom, and an isolated layer. The mathematical model for these examples describes the horizontal heterogeneities in a light field with regard to radiation polarization in a three dimensional planar atmosphere, delimited by a heterogeneous surface with diffuse reflection. The perturbation method was used to obtain vector transfer equations which correspond to the linear and nonlinear systems of polarization radiation transfer. The boundary value tasks for the vector transfer equation that is a parametric set and one dimensional are satisfied by the SFC of the nonlinear system, and are expressed through the SFC of linear approximation. As a consequence of the developed theory, formulas were obtained for analytical calculation of albedo in solving the task of dissemination of polarization radiation in the planetary atmosphere with uniform Lambert bottom.

Strelkov, S. A.; Sushkevich, T. A.

1983-01-01

80

Temperature and Radiative Heat Flux Measurements in Microgravity Jet Diffusion Flames  

NASA Technical Reports Server (NTRS)

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.

Ku, Jerry C.; Greenberg, Paul S.

1997-01-01

81

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

E-print Network

We describe and test an updated version of radiation-hydrodynamics (RHD) 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 a optically semi-thick medium, direct pressure on gas from ionising 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 us...

Rosdahl, J

2014-01-01

82

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

NASA Technical Reports Server (NTRS)

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.

Ressell, M. Ted; Turner, Michael S.

1989-01-01

83

Radiation Therapy  

MedlinePLUS

... treatment for kids or adults who have cancer . Radiation to Treat Cancer Cancer is a disease that ... don't get it very often. How Is Radiation Given? Cancer can be treated with radiation therapy ...

84

Radiation Therapy  

MedlinePLUS

Radiation Therapy Radiation therapy (sometimes referred to as radiotherapy, x-ray therapy or irradiation) has been used to treat many types of cancer for more than 100 years. Radiation therapy refers to the careful use of various ...

85

Radiation Emergencies  

MedlinePLUS

... Simulation Tools CDC Response, Japan 2011 Specific Hazards Radiation Emergencies Language: English Español (Spanish) Share Compartir If ... loved ones, and your pets. Learn More » Radiation and Your Health Radiation can affect the body ...

86

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, ...

87

Radiation Therapy  

MedlinePLUS

... weeks. New Techniques Newer radiation techniques such as proton beam radiotherapy, which uses a different form of ... requiring many more beams than conventional radiation therapy. Proton Beam Therapy compared to traditional photon beam radiation, ...

88

Nonthermal effects on microwave radiation on ionic diffusion in ionic crystalline ceramics  

SciTech Connect

Numerous claims have been made of observations that microwave heating of ceramics promotes faster processing or solid state reactions (e.g., sintering, bonding, tracer ion diffusion) than conventional furnace heating. These claims are controversial due to the absence of a verifiable theoretical explanation as well as questions on the interpretation of sample temperature measurements obtained in the presence of microwave fields or during microwave heating. A recent experimental investigation has clearly established that intense microwave fields can yield enhanced ion (or vacancy) diffusion in ionic crystalline ceramics. The results are in qualitative agreement with a model in which the microwave fields exert a ponderomotive or radiation pressure acting near the surfaces of NaCl crystals or grains. It is believed that this phenomenon explains the observations of microwave-enhanced tracer ion diffusion in higher temperature oxide ceramics and glasses. Future work will explore the role of this phenomenon in grain boundary diffusion and sintering during microwave processing of ceramics.

Freeman, S.A.; Booske, J.H.; Cooper, R.F. [Univ. of Wisconsin, Madison, WI (United States)

1995-12-31

89

Atmospheric radiation  

SciTech Connect

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

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

1991-01-01

90

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

E-print Network

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...

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

2000-01-01

91

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

NASA Technical Reports Server (NTRS)

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.

Plante, Ianik; Wu, Honglu

2014-01-01

92

Radiation Laws  

NSDL National Science Digital Library

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

Astronomy, Department O.; Knoxville, University O.

93

Impact of Changes in Diffuse Radiation on the Global Land Carbon Sink, 1901-2100  

NASA Astrophysics Data System (ADS)

Recent observational and theoretical studies have shown that changes in surface radiation that lead to increasing diffuse surface irradiance, enhance plant photosynthesis (Gu et al., 2003, Niyogi et al., 2004, Oliveira et al., 2007, Roderick et al., 2001). Solar radiation reaching the land surface has changed over the industrial era due to aerosols emitted from volcanoes and various anthropogenic sources (Kvalevag and Myhre, 2007). Such changes in total surface radiation are accompanied by changes in direct and diffuse surface solar radiation. Current global climate-carbon models do include the effects of changes in total surface radiation on the land biosphere but neglect the positive effects of increasing diffuse fraction on plant photosynthesis. In this study we estimate for the first time, the impact of variations in diffuse fraction on the land carbon sink using a global model (Mercado et al., 2007) modified to account for the effects of variations in both direct and diffuse radiation on canopy photosynthesis. We use meteorological forcing from the Climate Research Unit Data set. Additionally short wave and photosynthetic active radiation are reconstructed from the Hadley centre climate model, which accounts for the scattering and absorption of light by tropospheric and stratospheric aerosols and change in cloud properties due to indirect aerosol effects. References Gu L.H., Baldocchi D.D., Wofsy S.C., Munger J.W., Michalsky J.J., Urbanski S.P. & Boden T.A. (2003) Response of a deciduous forest to the Mount Pinatubo eruption: Enhanced photosynthesis. Science, 299, 2035-2038. M. M. Kvalevag and G. Myhre, J. Clim. 20, 4874 (2007). Mercado L.M., Huntingford C., Gash J.H.C., Cox P.M. & Jogireddy V. (2007) Improving the representation of radiation interception and photosynthesis for climate model applications. Tellus Series B-Chemical and Physical Meteorology, 59, 553-565. Niyogi D., Chang H.I., Saxena V.K., Holt T., Alapaty K., Booker F., Chen F., Davis K.J., Holben B., Matsui T., Meyers T., Oechel W.C., Pielke R.A., Wells R., Wilson K. & Xue Y.K. (2004) Direct observations of the effects of aerosol loading on net ecosystem CO2 exchanges over different landscapes. Geophysical Research Letters, 31. Oliveira P.H.F., Artaxo P., Pires C., De Lucca S., Procopio A., Holben B., Schafer J., Cardoso L.F., Wofsy S.C. & Rocha H.R. (2007) The effects of biomass burning aerosols and clouds on the CO2 flux in Amazonia. Tellus Series B-Chemical and Physical Meteorology, 59, 338-349. Roderick M.L., Farquhar G.D., Berry S.L. & Noble I.R. (2001) On the direct effect of clouds and atmospheric particles on the productivity and structure of vegetation. Oecologia, 129, 21-30.

Mercado, L.; Bellouin, N.; Sitch, S.; Boucher, O.; Huntingford, C.; Wild, M.; Cox, P. M.

2009-04-01

94

Image Reconstruction for Diffuse Optical Tomography Based on Radiative Transfer Equation  

PubMed Central

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 L2 regularization. Results also show the competitive performance of the split Bregman algorithm for the DOT image reconstruction with sparsity regularization compared with other existing L1 algorithms. PMID:25648064

Han, Bo; Tang, Jinping

2015-01-01

95

Diffusion Tensor Imaging of Brain Abnormalities Induced by Prenatal Exposure to Radiation in Rodents  

PubMed Central

We assessed brain abnormalities in rats exposed prenatally to radiation (X-rays) using magnetic resonance imaging (MRI) and histological experiments. Pregnant rats were divided into 4 groups: the control group (n?=?3) and 3 groups that were exposed to different radiation doses (0.5, 1.0, or 1.5 Gy; n?=?3 each). Brain abnormalities were assessed in 32 neonatal male rats (8 per group). Ex vivo T2-weighted imaging and diffusion tensor imaging (DTI) were performed using 11.7-T MRI. The expression of markers of myelin production (Kluver–Barrera staining, KB), nonpyramidal cells (calbindin-D28k staining, CaBP), and pyramidal cells (staining of the nonphosphorylated heavy-chain neurofilament SMI-32) were histologically evaluated. Decreased brain volume, increased ventricle volume, and thinner cortices were observed by MRI in irradiated rats. However, no abnormalities in the cortical 6-layered structure were observed via KB staining in radiation-exposed rats. The DTI color-coded map revealed a dose-dependent reduction in the anisotropic signal (vertical direction), which did not represent reduced numbers of pyramidal cells; rather, it indicated a signal reduction relative to the vertical direction because of low nerve cell density in the entire cortex. We conclude that DTI and histological experiments are useful tools for assessing cortical and hippocampal abnormalities after prenatal exposure to radiation in rats. PMID:25202992

Saito, Shigeyoshi; Sawada, Kazuhiko; Hirose, Miwa; Mori, Yuki; Yoshioka, Yoshichika; Murase, Kenya

2014-01-01

96

An experimental and theoretical study of radiative extinction of diffusion flames  

NASA Technical Reports Server (NTRS)

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.

Wichman, Indrek S.; Atreya, A.

1994-01-01

97

A multigrid preconditioner and automatic differentiation for non-equilibrium radiation diffusion problems  

SciTech Connect

We study the efficient solution of non-equilibrium radiation diffusion problems. An implicit time discretization leads to the solution of systems of non-linear equations which couple radiation energy and material temperature. We consider the implicit Euler method, the mid-point scheme, the two-step backward differentiation formula, and a two-stage implicit Runge-Kutta method for time discretization. We employ a Newton-Krylov method in the solution of arising non-linear problems. We describe the computation of the Jacobian matrix for Newton's method using automatic differentiation based on the operator overloading in Fortran 90. For GMRES iterations, we propose a simple multigrid preconditioner applied directly to the coupled linearized problems. We demonstrate the efficiency and scalability of the proposed solution procedure by solving one-dimensional and two-dimensional model problems.

Glowinski, Roland [Department of Mathematics, PGH 651, University of Houston, Houston, TX 77204-3008 (United States)]. E-mail: roland@math.uh.edu; Toivanen, Jari [Center for Research in Scientific Computation, Box 8205, North Carolina State University, Raleigh, NC 27695-8205 (United States)]. E-mail: jatoivan@ncsu.edu

2005-07-20

98

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

SciTech Connect

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.

Edwards, Jarrod D. [Department of Nuclear Engineering, 129 Zachry Engineering Center, TAMU 3133, Texas A and M University, College Station, Texas 77843 (United States); Morel, Jim E., E-mail: morel@tamu.ed [Department of Nuclear Engineering, 129 Zachry Engineering Center, TAMU 3133, Texas A and M University, College Station, Texas 77843 (United States); Knoll, Dana A. [Fluid Dynamics and Solid Mechanics Group T-3, Los Alamos National Laboratory, P.O. Box 1663, MS B216, Los Alamos, NM 87545 (United States)

2011-02-20

99

Noninvasive diffuse optical monitoring of head and neck tumor blood flow and oxygenation during radiation delivery  

PubMed Central

This study explored using a novel diffuse correlation spectroscopy (DCS) flow-oximeter to noninvasively monitor blood flow and oxygenation changes in head and neck tumors during radiation delivery. A fiber-optic probe connected to the DCS flow-oximeter was placed on the surface of the radiologically/clinically involved cervical lymph node. The DCS flow-oximeter in the treatment room was remotely operated by a computer in the control room. From the early measurements, abnormal signals were observed when the optical device was placed in close proximity to the radiation beams. Through phantom tests, the artifacts were shown to be caused by scattered x rays and consequentially avoided by moving the optical device away from the x-ray beams. Eleven patients with head and neck tumors were continually measured once a week over a treatment period of seven weeks, although there were some missing data due to the patient related events. Large inter-patient variations in tumor hemodynamic responses were observed during radiation delivery. A significant increase in tumor blood flow was observed at the first week of treatment, which may be a physiologic response to hypoxia created by radiation oxygen consumption. Only small and insignificant changes were found in tumor blood oxygenation, suggesting that oxygen utilizations in tumors during the short period of fractional radiation deliveries were either minimal or balanced by other effects such as blood flow regulation. Further investigations in a large patient population are needed to correlate the individual hemodynamic responses with the clinical outcomes for determining the prognostic value of optical measurements. PMID:22312579

Dong, Lixin; Kudrimoti, Mahesh; Cheng, Ran; Shang, Yu; Johnson, Ellis L.; Stevens, Scott D.; Shelton, Brent J.; Yu, Guoqiang

2012-01-01

100

Measurements and modeling of soot formation and radiation in microgravity jet diffusion flames  

SciTech Connect

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. On modeling, the authors 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 H{sub 2}O and CO{sub 2}. 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 the data for 1-g and 0-g laminar jet flames as well as 1-g turbulent jet flames.

Ku, J.C.; Tong, L. [Wayne State Univ., Detroit, MI (United States). Mechanical Engineering Dept.; Greenberg, P.S. [NASA Lewis Research Center, Cleveland, OH (United States). Microgravity Combustion Branch

1996-12-31

101

Frequency and quality of radiation monitoring of construction workers at two gaseous diffusion plants.  

PubMed

Construction workers were and are considered temporary workers at many construction sites. Since World War II, large numbers of construction workers were employed at U.S. Department of Energy nuclear weapons sites for periods ranging from a few days to over 30 years. These workers performed tasks during new construction and maintenance, repair, renovation, and demolition of existing facilities. Such tasks may involve emergency situations, and may entail opportunities for significant radiation exposures. This paper provides data from interviews with more than 750 construction workers at two gaseous diffusion plants (GDPs) at Paducah, Kentucky, and Portsmouth, Ohio regarding radiation monitoring practices. The aim was to determine the extent to which workers believed they were monitored during tasks involving potential radiation exposures. The adequacy of monitoring practices is important for two reasons: (a) Protecting workers from exposures: Construction workers were employed by sub-contractors, and may frequently been excluded from safety and health programs provided to permanent employees; and (b) Supporting claims for compensation: The Energy Employees Occupational Illness Compensation Program Act (EEOICPA) requires dose reconstruction of radiation exposures for most workers who file a claim regarding cancer. The use of monitoring data for radiation to qualify a worker means that there should be valid and complete monitoring during the work time at the various nuclear plants or workers may be unfairly denied compensation. The worker interviews from Paducah and Portsmouth were considered especially useful because these sites were designated as Special Exposure Cohorts (SECs) and the workers did not have to have a dose reconstruction to qualify for compensation for most cancers. Therefore, their responses were less likely to be affected by compensation concerns. Interview questions included asking for information regarding whether monitoring was performed, how often, and the maintenance (calibration) of monitoring equipment (devices). PMID:17119219

Bingham, Eula; Ringen, Knut; Dement, John; Cameron, Wilfrid; McGowan, William; Welch, Laura; Quinn, Patricia

2006-09-01

102

Diffusion of fission products and radiation damage in SiC  

NASA Astrophysics Data System (ADS)

A major problem with most of the present nuclear reactors is their safety in terms of the release of radioactivity into the environment during accidents. In some of the future nuclear reactor designs, i.e. Generation IV reactors, the fuel is in the form of coated spherical particles, i.e. TRISO (acronym for triple coated isotropic) particles. The main function of these coating layers is to act as diffusion barriers for radioactive fission products, thereby keeping these fission products within the fuel particles, even under accident conditions. The most important coating layer is composed of polycrystalline 3C-SiC. This paper reviews the diffusion of the important fission products (silver, caesium, iodine and strontium) in SiC. Because radiation damage can induce and enhance diffusion, the paper also briefly reviews damage created by energetic neutrons and ions at elevated temperatures, i.e. the temperatures at which the modern reactors will operate, and the annealing of the damage. The interaction between SiC and some fission products (such as Pd and I) is also briefly discussed. As shown, one of the key advantages of SiC is its radiation hardness at elevated temperatures, i.e. SiC is not amorphized by neutrons or bombardment at substrate temperatures above 350 °C. Based on the diffusion coefficients of the fission products considered, the review shows that at the normal operating temperatures of these new reactors (i.e. less than 950 °C) the SiC coating layer is a good diffusion barrier for these fission products. However, at higher temperatures the design of the coated particles needs to be adapted, possibly by adding a thin layer of ZrC.

Malherbe, Johan B.

2013-11-01

103

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

SciTech Connect

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.

Evans, Thomas M., E-mail: evanstm@ornl.gov [Oak Ridge National Laboratory, 1 Bethel Valley Rd., Oak Ridge, TN 37831 (United States); Mosher, Scott W., E-mail: moshersw@ornl.gov [Oak Ridge National Laboratory, 1 Bethel Valley Rd., Oak Ridge, TN 37831 (United States); Slattery, Stuart R., E-mail: sslattery@wisc.edu [University of Wisconsin–Madison, 1500 Engineering Dr., Madison, WI 53716 (United States); Hamilton, Steven P., E-mail: hamiltonsp@ornl.gov [Oak Ridge National Laboratory, 1 Bethel Valley Rd., Oak Ridge, TN 37831 (United States)

2014-02-01

104

Radiative heating of interstellar grains falling toward the solar nebula: 1-D diffusion calculations  

NASA Technical Reports Server (NTRS)

As the dense molecular cloud that was the precursor of our Solar System was collapsing to form a protosun and the surrounding solar-nebula accretion disk, infalling interstellar grains were heated much more effectively by radiation from the forming protosun than by radiation from the disk's accretion shock. Accordingly, we have estimated the temperatures experienced by these infalling grains using radiative diffusion calculations whose sole energy source is radiation from the protosun. Although the calculations are 1-dimensional, they make use of 2-D, cylindrically symmetric models of the density structure of a collapsing, rotating cloud. The temperature calculations also utilize recent models for the composition and radiative properties of interstellar grains (Pollack et al. 1994. Astrophys. J. 421, 615-639), thereby allowing us to estimate which grain species might have survived, intact, to the disk accretion shock and what accretion rates and molecular-cloud rotation rates aid that survival. Not surprisingly, we find that the large uncertainties in the free parameter values allow a wide range of grain-survival results: (1) For physically plausible high accretion rates or low rotation rates (which produce small accretion disks), all of the infalling grain species, even the refractory silicates and iron, will vaporize in the protosun's radiation field before reaching the disk accretion shock. (2) For equally plausible low accretion rates or high rotation rates (which produce large accretion disks), all non-ice species, even volatile organics, will survive intact to the disk accretion shock. These grain-survival conclusions are subject to several limitations which need to be addressed by future, more sophisticated radiative-transfer models. Nevertheless, our results can serve as useful inputs to models of the processing that interstellar grains undergo at the solar nebula's accretion shock, and thus help address the broader question of interstellar inheritance in the solar nebula and present Solar System. These results may also help constrain the size of the accretion disk: for example, if we require that the calculations produce partial survival of organic grains into the solar nebula, we infer that some material entered the disk intact at distances comparable to or greater than a few AU. Intriguingly, this is comparable to the heliocentric distance that separates the C-rich outer parts of the current Solar System from the C-poor inner regions.

Simonelli, D. P.; Pollack, J. B.; McKay, C. P.

1997-01-01

105

Space Radiation  

NASA Technical Reports Server (NTRS)

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.

Wu, Honglu

2006-01-01

106

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

NASA Astrophysics Data System (ADS)

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.

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

2012-06-01

107

On the reciprocity relationship between direct field radiation and diffuse reverberant loading  

NASA Astrophysics Data System (ADS)

This analysis is concerned with the derivation of a ``diffuse field'' reciprocity relationship between the diffuse field excitation of a connection to a structural or acoustic subsystem and the radiation impedance of the connection. Such a relationship has been derived previously for connections described by a single degree of freedom. In the present work it is shown that the diffuse-field reciprocity relationship also arises when describing the ensemble average response of connections to structural or acoustic subsystems with uncertain boundaries. Furthermore, it is shown that the existing diffuse-field reciprocity relationship can be extended to encompass connections that possess an arbitrary number of degrees of freedom. The present work has application to (i) the calculation of the diffuse field response of structural-acoustic systems modeled by Finite Elements, Boundary Elements, and Infinite Elements; (ii) the general calculation of the Coupling Loss Factors employed in Statistical Energy Analysis (SEA); and (iii) the derivation of an alternative analysis method for describing the dynamic interactions of coupled subsystems with uncertain boundaries (a generalized ``boundary'' approach to SEA). .

Shorter, P. J.; Langley, R. S.

2005-01-01

108

Modeling Heat Conduction and Radiation Transport with the Diffusion Equation in NIF ALE-AMR  

SciTech Connect

The ALE-AMR code developed for NIF is a multi-material hydro-code that models target assembly fragmentation in the aftermath of a shot. The combination of ALE (Arbitrary Lagrangian Eulerian) hydro with AMR (Adaptive Mesh Refinement) allows the code to model a wide range of physical conditions and spatial scales. The large range of temperatures encountered in the NIF target chamber can lead to significant fluxes of energy due to thermal conduction and radiative transport. These physical effects can be modeled approximately with the aid of the diffusion equation. We present a novel method for the solution of the diffusion equation on a composite mesh in order to capture these physical effects.

Fisher, A C; Bailey, D S; Kaiser, T B; Gunney, B N; Masters, N D; Koniges, A E; Eder, D C; Anderson, R W

2009-10-06

109

Diffusion Weighted MRI and MRS to Differentiate Radiation Necrosis and Recurrent Disease in Gliomas  

NASA Astrophysics Data System (ADS)

A difficulty encountered in the diagnosis of patients with gliomas is the differentiation between recurrent disease and Radiation Induced Necrosis (RIN). Both can appear as ‘enhancing lesions’ on a typical T2 weighted MRI scan. Magnetic Resonance Spectroscopy (MRS) and Diffusion Weighted MRI (DWMRI) have the potential to be helpful regarding this differentiation. MRS has the ability to measure the concentration of brain metabolites, such as Choline, Creatin and N- Acetyl Aspartate, the ratios of which have been shown to discriminate between RIN and recurrent disease. DWMRI has been linked via a rise in the Apparent Diffusion Coefficient (ADC) to successful treatment of disease. Using both of these complimentary non-invasive imaging modalities, we intend to initiate an imaging protocol whereby we will study how best to combine metabolite ratios and ADC values to obtain the most useful information in the least amount of scan time. We will look for correlations over time between ADC values, and MRS, among different sized voxels.

Ewell, Lars

2006-03-01

110

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

NASA Astrophysics Data System (ADS)

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.

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

2013-11-01

111

Influence of radiative loss on nitric oxide formation in counterflow diffusion flames at high pressure  

SciTech Connect

A theoretical analysis is given of the effect of nonluminous thermal radiation on the properties of counterflow diffusion flames at high pressure. The self-consistent analysis includes an expression for gas band radiant dissipation in the energy equation of a counterflow flame solver. NO[sub x] formation rates and other properties are studied as a function of strain rate for adiabatic, optically thin, and optical thickness-corrected flames. For adiabatic flames, NO[sub x] concentration and flame temperature increase continuously with decreasing strain rate. For radiating flames, a temperature level off is exhibited due to the competing effects of heat loss and extent of reaction as strain rate (inverse residence time) decreases. For the very lowest strain rates, up to 5% of the flame enthalpy is converted to radiation, and optical thickness corrections start to become important. Certain factors that need to be taken into account in relating the isolated flamelet results to practical gas turbine combustors are also discussed.

Vranos, A. (AB Research Associates, South Windsor, CT (United States)); Hall, R.J. (United Technologies Research Center, East Hartford, CT (United States))

1993-05-01

112

Radiation Therapy  

MedlinePLUS

... for e-updates Please leave this field empty Radiation Therapy SHARE Share on Facebook Preview your comments ... Treatment and Care > Treatments Listen The goal of radiation therapy is to destroy or stop brain tumor ...

113

Measuring Radiation  

MedlinePLUS

... or beta particles, gamma rays, x-rays, or neutrons, a quantity of radioactive material is expressed in ... larger than the absorbed dose for alpha and neutron radiation, because these types of radiation are more ...

114

Response of radiation belt simulations to different radial diffusion coefficients for relativistic and ultra-relativistic electrons  

NASA Astrophysics Data System (ADS)

Two parameterizations of the resonant wave-particle interactions of electrons with ULF waves in the magnetosphere by Brautigam and Albert [2000] and Ozeke et al. [2012] are evaluated using the Versatile Electron Radiation Belt (VERB) diffusion code to estimate the effect of changing a diffusion coefficient on the radiation belt simulation. The period of investigation includes geomagnetically quiet and active time. The simulations take into account wave-particle interactions represented by radial diffusion transport, local acceleration, losses due to pitch-angle diffusion, and mixed diffusion. 1. Brautigam, D. H., and J. M. Albert (2000), Radial diffusion analysis of outer radiation belt electrons during the October 9, 1990, magnetic storm, J. Geophys. Res., 105(A1), 291-309, doi:10.1029/1999JA900344 2. Ozeke, L. G., I. R. Mann, K. R. Murphy, I. J. Rae, D. K. Milling, S. R. Elkington, A. A. Chan, and H. J. Singer (2012), ULF wave derived radiation belt radial diffusion coefficients, J. Geophys. Res., 117, A04222, doi:10.1029/2011JA017463.

Drozdov, Alexander; Mann, Ian; Baker, Daniel N.; Subbotin, Dmitriy; Ozeke, Louis; Shprits, Yuri; Kellerman, Adam

115

Radiation Exposure  

MedlinePLUS

Radiation is energy that travels in the form of waves or high-speed 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 ...

116

Combination of magnetic resonance imaging and diffuse optical spectroscopy to predict radiation response in the breast: an exploratory pilot study  

NASA Astrophysics Data System (ADS)

Radiation therapy (RT) is a standard treatment after lumpectomy for breast cancer, involving a typical course of approximately 6-7 weeks of daily treatment. Many women find this cumbersome and costly, and therefore many are left with the option of mastectomy. Many groups are now investigating novel ways to deliver RT, by using different techniques and shortening the course of treatment. However, the efficacy and side effects of these strategies are not known. In this project, we wish to develop noninvasive imaging tools that would allow us to measure radiation dose effects in women with breast cancer. We hope this will lead to new ways to identify individuals who may not need radiation therapy, who may safely be treated with new accelerated techniques, or who should be treated with the standard radiation therapy approach. We propose to study the effect of radiation therapy using a combination of two imaging modalities: 1) magnetic resonance imaging (MRI) which will provide detailed information on breast structures and blood vessels and 2) near infra-red diffuse optical spectroscopy (DOS), which measures local biologic properties of breast tissue. Our hypothesis is that by using a combination of modalities we will be able to better characterize radiation effects in breast tissue, by measuring differences between the radiated and non-irradiated breast. The development of novel non-invasive tools providing information about how individuals respond to radiation therapy can lead to important improvement of radiation treatment, and ultimately help guide individualized treatment programs in the future.

Klifa, C.; Hattangadi, J.; Watkins, M.; Li, A.; Sakata, T.; Tromberg, B.; Hylton, N.; Park, C.

2007-02-01

117

Numerical study of double-diffusion convection coupled to radiation in a square cavity filled with a participating grey gas  

NASA Astrophysics Data System (ADS)

This paper presents numerical solutions for the coupled radiation and natural convection heat transfer by double diffusion in a square cavity. The governing differential equations are solved by a finite-volume method, by adopting the SIMPLER algorithm for pressure-velocity coupling. The discrete ordinate method is used in modelling the radiative transfer equation. The working fluid is considered as grey, absorbing, emitting and not scattering. The walls of the enclosure are assumed to be opaque, diffuse and grey. A parametric study is performed to illustrate the influence of the Rayleigh number, the buoyancy number, the Lewis number and the optical thickness on the flow structure, the heat and mass transfer. The results obtained can be used as benchmark solutions for the validation of the codes treating the combined natural convection heat transfer by double diffusion and radiation.

Mezrhab, A.; Lemonnier, D.; Meftah, S.; Benbrik, A.

2008-10-01

118

DIBSyRCH: The Diffuse Interstellar Band Synchrotron Radiation Carrier Hunt: New Tools  

NASA Astrophysics Data System (ADS)

The identity of the carrier molecules of the Diffuse Interstellar Bands (DIBs) is the most durable mystery of spectroscopic astronomy. The DIBs are persistent absorption features, >300 total, observed along many lines of sight through the Interstellar Medium (ISM). The DIBs are scattered throughout the visible and near infrared, with widths in the 2-100 cm-1 range. For nearly a century, laboratory spectroscopists have struggled to match astrophysical wavelengths to laboratory wavelengths of known molecules including a variety of stable molecules, radicals, cations, and anions. Many researchers have hypothesized that hydrocarbon molecules are responsible for the DIBs, due to the rich chemistry and high cosmic abundance of carbon and hydrogen. Though large Polycyclic Aromatic Hydrocarbons (PAHs) are now suspected to be the source of the DIBs, no definitive matches have yet been made to laboratory PAH spectra. Aromatic clusters are also thought to be an important constituent of the interstellar dust distribution and may contribute to the 2175 Å "bump" in the interstellar extinction curve. The Diffuse Interstellar Band Synchrotron Radiation Carrier Hunt (DIBSyRCH) experiment has been built at the Synchrotron Radiation Center (SRC) to test these hypotheses by conducting a spectroscopic survey of a broad range of cold, gas phase and clustered PAH molecules and ions. Using a custom echelle spectrograph and the innovative Cryogenic Circulating Advective Multi-Pass (CCAMP) absorption cell, we routinely achieve a detection sensitivity to molecular densities on the order of 107 cm-3 with a signal-to-noise ratio of 10,000 in 60 seconds of data collection in the visible. This instrument, coupled with the high spectral radiance of the synchrotron radiation continuum from the SRC's White Light Beamline, permits rapid acquisition of spectra covering broad wavelength regions with resolution appropriate for the DIBs. In order to obtain astrophysically relevant spectra of low-temperature PAHs, the molecules are entrained in a flow of cold neon buffer gas inside the CCAMP cell. A multi-pass optical cavity using special high-reflectivity broadband mirrors extends the absorption path length to hundreds of meters. The CCAMP cell combined with the broad spectral coverage and high spectral radiance of synchrotron radiation make this experiment uniquely suited to the DIB carrier search. Several generations of resistively heated and plasma heated crucibles have been used in the CCAMP to introduce PAHs. All have produced PAH clusters large enough to scatter light the synchrotron beam and reduce signal to noise. A new gas injection system is under development. An intense radio frequency dielectric barrier discharge and higher flow rates should reduce cluster formation.

Stockett, M. H.; Wood, M. P.; Lawler, J. E.

2010-11-01

119

Radiation Chemistry  

NASA Astrophysics Data System (ADS)

Ionizing radiation causes chemical changes in the molecules of the interacting medium. The initial molecules change to new molecules, resulting in changes of the physical, chemical, and eventually biological properties of the material. For instance, water decomposes to its elements H2 and O2. In polymers, degradation and crosslinking take place. In biopolymers, e.g., DNS strand breaks and other alterations occur. Such changes are to be avoided in some cases (radiation protection), however, in other cases they are used for technological purposes (radiation processing). This chapter introduces radiation chemistry by discussing the sources of ionizing radiation (radionuclide sources, machine sources), absorption of radiation energy, techniques used in radiation chemistry research, and methods of absorbed energy (absorbed dose) measurements. Radiation chemistry of different classes of inorganic (water and aqueous solutions, inorganic solids, ionic liquids (ILs)) and organic substances (hydrocarbons, halogenated compounds, polymers, and biomolecules) is discussed in concise form together with theoretical and experimental backgrounds. An essential part of the chapter is the introduction of radiation processing technologies in the fields of polymer chemistry, food processing, and sterilization. The application of radiation chemistry to nuclear technology and to protection of environment (flue gas treatment, wastewater treatment) is also discussed.

Wojnárovits, L.

120

Derivation and Solution of Multifrequency Radiation Diffusion Equations for Homogeneous Refractive Lossy Media  

SciTech Connect

Starting from the radiation transport equation for homogeneous, refractive lossy media, we derive the corresponding time-dependent multifrequency 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 system is coupled to a diffusion equation for the matter temperature. We are interested in modeling annealing of silica (SiO{sub 2}). We derive boundary conditions at a planar air-silica interface taking account of reflectivities. The spectral dimension is discretized into a finite number of intervals leading to a system of multigroup diffusion equations. Three simulations are presented. One models cooling of a silica slab, initially at 2500 K, for 10 s. The other two are 1D and 2D simulations of irradiating silica with a CO{sub 2} laser, {lambda} = 10.59 {micro}m. In 2D, we anneal a disk (radius = 0.4, thickness = 0.4 cm) with a laser, Gaussian profile (r{sub 0} = 0.5 mm for 1/e decay).

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

2010-01-05

121

Soot formation, transport, and radiation in unsteady diffusion flames : LDRD final report.  

SciTech Connect

Fires pose the dominant risk to the safety and security of nuclear weapons, nuclear transport containers, and DOE and DoD facilities. The thermal hazard from these fires primarily results from radiant emission from high-temperature flame soot. Therefore, it is necessary to understand the local transport and chemical phenomena that determine the distributions of soot concentration, optical properties, and temperature in order to develop and validate constitutive models for large-scale, high-fidelity fire simulations. This report summarizes the findings of a Laboratory Directed Research and Development (LDRD) project devoted to obtaining the critical experimental information needed to develop such constitutive models. A combination of laser diagnostics and extractive measurement techniques have been employed in both steady and pulsed laminar diffusion flames of methane, ethylene, and JP-8 surrogate burning in air. For methane and ethylene, both slot and coannular flame geometries were investigated, as well as normal and inverse diffusion flame geometries. For the JP-8 surrogate, coannular normal diffusion flames were investigated. Soot concentrations, polycyclic aromatic hydrocarbon (PAH) laser-induced fluorescence (LIF) signals, hydroxyl radical (OH) LIF, acetylene and water vapor concentrations, soot zone temperatures, and the velocity field were all successfully measured in both steady and unsteady versions of these various flames. In addition, measurements were made of the soot microstructure, soot dimensionless extinction coefficient (&), and the local radiant heat flux. Taken together, these measurements comprise a unique, extensive database for future development and validation of models of soot formation, transport, and radiation.

Suo-Anttila, Jill Marie (Sandia National Laboratories, Albuquerque, NM); Williams, Timothy C.; Shaddix, Christopher R.; Jensen, Kirk A. (Sandia National Laboratories, Albuquerque, NM); Blevins, Linda Gail; Kearney, Sean Patrick (Sandia National Laboratories, Albuquerque, NM); Schefer, Robert W.

2004-10-01

122

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

SciTech Connect

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.

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

2014-04-01

123

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

SciTech Connect

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.

Feng, Tao, E-mail: fengtao2@mail.ustc.edu.cn [School of Mathematical Sciences, University of Science and Technology of China, Hefei 230052 (China) [School of Mathematical Sciences, University of Science and Technology of China, Hefei 230052 (China); Graduate School of China Academy Engineering Physics, Beijing 100083 (China); An, Hengbin, E-mail: an_hengbin@iapcm.ac.cn [National Key Laboratory of Computational Physics, Institute of Applied Physics and Computational Mathematics, Beijing 100094 (China)] [National Key Laboratory of Computational Physics, Institute of Applied Physics and Computational Mathematics, Beijing 100094 (China); Yu, Xijun, E-mail: yuxj@iapcm.ac.cn [National Key Laboratory of Computational Physics, Institute of Applied Physics and Computational Mathematics, Beijing 100094 (China)] [National Key Laboratory of Computational Physics, Institute of Applied Physics and Computational Mathematics, Beijing 100094 (China); Li, Qin, E-mail: liqin@lsec.cc.ac.cn [Chinese Academy of Mathematics and Systems Science, Beijing 100190 (China)] [Chinese Academy of Mathematics and Systems Science, Beijing 100190 (China); Zhang, Rongpei, E-mail: zhangrongpei@163.com [Graduate School of China Academy Engineering Physics, Beijing 100083 (China)] [Graduate School of China Academy Engineering Physics, Beijing 100083 (China)

2013-03-01

124

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

NASA Technical Reports Server (NTRS)

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

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

2012-01-01

125

Radiating Charge  

NSDL National Science Digital Library

The electric field lines from a point charge evolve in time as the charge moves. Watch radiation propagate outward at the speed of light as you wiggle the charge. Stop a moving charge to see bremsstrahlung (braking) radiation. Explore the radiation patterns as the charge moves with sinusoidal, circular, or linear motion. You can move the charge any way you like, as long as you donât exceed the speed of light.

Simulations, Phet I.; Dubson, Michael; Paul, Ariel

2013-02-01

126

Radiator technology  

NASA Technical Reports Server (NTRS)

Radiator technology is discussed in the context of the Civilian Space Technology Initiative's (CSTI's) high capacity power-thermal management project. The CSTI project is a subset of a project to develop a piloted Mars nuclear electric propulsion (NEP) vehicle. The following topics are presented in vugraph form: advanced radiator concepts; heat pipe codes and testing; composite materials; radiator design and integration; and surface morphology.

Juhasz, Albert J.

1993-01-01

127

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

E-print Network

for a supercritical radiating shock. The upstream precursor region begins at ?0 = 1 and ends at ?p, where Tp = Tf . Continuity of the radiation flux between state-p and state-s defines the embedded hydrodynamic shock, and de- termines the value... thick. Adapted from [5, 6]. . . . . . . . 75 Figure IV.7 Simplified model of the Zel’dovich spike proposed by Drake [5, 6]. For a supercritical radiating shock the upstream precursor region approaches the shock discontinuity with temperature, Tf...

Ferguson, Jim Michael

2014-01-10

128

Electron and proton radiation belt dynamic simulations during storm periods: A new asymmetric convection-diffusion model  

Microsoft Academic Search

Using a convection-diffusion theory, we give the first results from a four-dimensional model of electron and proton radiation belts. This work is based on the numerical solution of a convection-diffusion equation taking into account (1) for protons, the deceleration of protons by the free and bounded thermospheric and ionospheric electrons, the charge exchange loss process, radial and azimuthal transports, and

S. Bourdarie; D. Boscher; T. Beutier; J.-A. Sauvaud; M. Blanc

1997-01-01

129

Ann. Geophysicae 14, 1051--1059 (1996) EGS --Springer-Verlag 1996 Diffuse solar radiation and associated meteorological  

E-print Network

and associated meteorological parameters in India A. B. Bhattacharya, S. K. Kar, R. Bhattacharya Department are presented together with some meteorological parameters. The monthly values of diffuse radiation between solar activity and meteorological phenomena made an interesting study during the last few

Boyer, Edmond

130

Reanalysis of relativistic radiation belt electron fluxes using CRRES satellite data, a radial diffusion model, and a Kalman filter  

Microsoft Academic Search

In this study we perform a reanalysis of the sparse MEA CRRES relativistic electron data using a relatively simple one-dimensional radial diffusion model and a Kalman filtering approach. By combining observations with the model in an optimal way we produce a high time and space resolution reanalysis of the radiation belt electron fluxes over a 50-d period starting on 18

Yuri Shprits; Dmitri Kondrashov; Yue Chen; Richard Thorne; Michael Ghil; Reiner Friedel; Geoff Reeves

2007-01-01

131

Diffuse fluorescence tomography based on the radiative transfer equation for small animal imaging  

NASA Astrophysics Data System (ADS)

Diffuse florescence tomography (DFT) as a high-sensitivity optical molecular imaging tool, can be applied to in vivo visualize interior cellular and molecular events for small-animal disease model through quantitatively recovering biodistributions of specific molecular probes. In DFT, the radiative transfer equation (RTE) and its approximation, such as the diffuse equation (DE), have been used as the forward models. The RTE-based DFT methodology is more suitable for biological tissue having void-like regions and the near-source area as in the situations of small animal imaging. We present a RTE-based scheme for the steady state DFT, which combines the discrete solid angle method and the finite difference method to obtain numerical solutions of the 2D steady RTE, with the natural boundary condition and collimating light source model. The approach is validated using the forward data from the Monte Carlo simulation for its better performances in the spatial resolution and reconstruction fidelity compared to the DE-based scheme.

Wang, Yihan; Zhang, Limin; Zhao, Huijuan; Gao, Feng; Li, Jiao

2014-02-01

132

Understanding Radiation.  

ERIC Educational Resources Information Center

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…

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

133

Radiative processes  

NASA Technical Reports Server (NTRS)

Solar radiation and the processes that control its deposition in the Earth atmosphere are considered. The published data obtained since 1978 define a reference solar spectral irradiance for use in atmospheric chemical and dynamical studies, while long term satellite measurements are now providing information on variations in the output of the Sun over a range of time scales. As concerns absorption of solar radiation in the atmosphere, new cross section data for molecular oxygen and ozone are now available. Line-by-line calculations used to predict infrared flux divergences, both as regards assumptions made in radiative transfer calculations and in the spectroscopic parameters used as inputs are examined. Also examined are the influence of radiative processes on planetary scale wave activity, photochemical acceleration of radiative damping, and the breakdown of local thermodynamic equilibrium at mesospheric altitudes.

Frederick, J. E.; Leovy, C.; Anderson, D. E., Jr.; Anderson, G. P.; Dickinson, R. E.; Drayson, S. R.; Fels, S.; Hall, L. A.; Kiehl, J.; Mentall, J. E.

1985-01-01

134

Dependence on latitude of the relation between the diffuse fraction of solar radiation and the radiation and the ratio of global-to-extraterrestrial radiation for monthly average daily values  

Microsoft Academic Search

An approach for the prediction of the monthly average daily diffuse radiation, {bar H}{sub d}, was proposed by Page in 1961. The Page method is based on the use of the linear correlation {bar H}{sub d}\\/{bar H} = c + d{bar H}\\/{bar H}{sub o}, where {bar H} and {bar H}{sub o} are, respectively, the monthly average daily values of global

A Soler

1990-01-01

135

Simulation Study of Diffusive Synchrotron Radiation from Hot Spots in Relativistic Jets such as M87  

NASA Astrophysics Data System (ADS)

We propose to apply numerical simulations and modeling to obtain emission spectrum from relativistic shocks and to compare the emission spectrum with observed optical-X-ray spectra from the M87 jet and 3C273. In particular, the project involves the study of relativistic collisionless shocks associated with knots and other optical structures {synchrotron spectrum models and break frequencies} observed in the kpc scale jet from knot HST-1 to knot A. Recent PIC simulations have revealed that in collisionless shocks, plasma waves and their associated instabilities {e.g., the Weibel, Buneman and other two-stream instabilities} are responsible for particle {electron, positron, and ion} acceleration and magnetic field generation. A 3-D relativistic electromagnetic particle {REMP} code will be used to investigate the shock processes in unmagnetized and magnetized electron-ion and electron-positron plasmas in order to obtain self-consistent spectra based on the trajectories of electrons in inhomogeneous magnetic fields. The diffusive synchrotron radiation {DSR} {jitter radiation} theory {Fleishman 2006; Medvedev 2006} shows that the synchrotron radiation spectrum produced by relativistic electrons in the jet is modified by the presence of small-scale random magnetic fields assumed to be generated by the Weibel instability. A high-frequency power-law component to the spectrum is yielded by taking account of the perturbations to the electron trajectories as a result of small-scale magnetic fields, which deviate from the standard synchrotron spectrum, especially at the high frequency. In our investigations, the density of the plasmas, the ambient magnetic field strength and direction, and jet Lorentz factor will be varied in order to evaluate the effect of changes in macroscopic properties {deceleration in jet velocity} that might be expected along the M87 jet. Emission spectra calculated based on electron trajectories in collisionless relativistic shocks {hot spots} generated by the Weibel instability in our simulations and its comparison with observations will enable us to address the radio-optical-X-ray spectra and its variability in M87 and other relativistic sources.

Nishikawa, Ken-Ichi

2006-07-01

136

[Radiation carcinogenesis].  

PubMed

Misrepair of DNA damage induced by ionizing radiation is a potential cause of carcinogenesis following exposure to radiation. Radiation exposure increases the incidence of the same types of mutations that occur spontaneously in a given population. A high incidence of DNA double-strand breaks is characteristic of damage by ionizing radiation compared with those induced by other environmental mutagens. In China, residents living in areas with high level background radiation(6mSv/y) had a significantly higher frequency of dicentric and ring chromosomes compared to that for the residents living in the control areas(2mSv/y). Radiation-associated increases in risk were seen for most sites. Gender-averaged excess absolute risk rates estimated at age 70, after exposure at age 30, differ in the sites, and the risks of gastric cancer, breast cancer, colon cancer, and lung cancer were highly increased, in that order. Latent periods for the development of leukemia and thyroid cancer after radiation exposure at ages younger than 18 were shorter compared to those for other solid cancers. PMID:24231698

Hosoi, Yoshio

2013-11-01

137

Radiation therapy  

MedlinePLUS

Radiation therapy uses high-powered x-rays, particles, or radioactive seeds to kill cancer cells. ... most common form. This method carefully aims high-powered x-rays or particles directly at the tumor ...

138

Radiation sickness  

MedlinePLUS

... tissue . X-rays, gamma rays, and particle bombardment (neutron beam, electron beam, protons, mesons, and others) give ... not being treated or studied during x-ray imaging tests or radiation therapy.

139

Radiation enteritis  

SciTech Connect

As the population receiving radiation therapy grows, so does the incidence of chronic radiation enteritis. A review of the pathology of chronic radiation enteritis reveals fibrosis, endarteritis, edema, fragility, perforation, and partial obstruction. Conservative management of patients with this disease is common. Because the obstruction is only partial, decompression is easily achieved with nasogastric suction and parenteral support. The patient is then often discharged on a liquid-to-soft diet. This therapeutic strategy does nothing for the underlying pathology. The problem, sooner or later, will return with the patient further depleted by the chronic radiation enteritis. We think surgical intervention is appropriate when the diagnosis of chronic radiation enteritis is assumed. The surgery in relation to this disease is high risk with a 30% mortality and 100% expensive morbidity. Early intervention seems to decrease these figures. All anastomoses, if possible, should be outside the irradiated area. Trapped pelvic loops of intestine should be left in place and a bypass procedure with decompressing enterostomies accomplished. The surgery should be performed by a surgeon with extensive experience with all kinds of bowel obstruction as well as experience in performing surgery in radiated tissue.

O'Brien, P.H.; Jenrette, J.M. III; Garvin, A.J.

1987-09-01

140

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

NASA Technical Reports Server (NTRS)

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.

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

1973-01-01

141

WEE1 kinase inhibition enhances the radiation response of diffuse intrinsic pontine gliomas.  

PubMed

Diffuse intrinsic pontine glioma (DIPG) is a fatal pediatric disease. Thus far, no therapeutic agent has proven beneficial in the treatment of this malignancy. Therefore, conventional DNA-damaging radiotherapy remains the standard treatment, providing transient neurologic improvement without improving the probability of overall survival. During radiotherapy, WEE1 kinase controls the G(2) cell-cycle checkpoint, allowing for repair of irradiation (IR)-induced DNA damage. Here, we show that WEE1 kinase is one of the highest overexpressed kinases in primary DIPG tissues compared with matching non-neoplastic brain tissues. Inhibition of WEE1 by MK-1775 treatment of DIPG cells inhibited the IR-induced WEE1-mediated phosphorylation of CDC2, resulting in reduced G(2)-M arrest and decreased cell viability. Finally, we show that MK-1775 enhances the radiation response of E98-Fluc-mCherry DIPG mouse xenografts. Altogether, these results show that inhibition of WEE1 kinase in conjunction with radiotherapy holds potential as a therapeutic approach for the treatment of DIPG. PMID:23270927

Caretti, Viola; Hiddingh, Lotte; Lagerweij, Tonny; Schellen, Pepijn; Koken, Phil W; Hulleman, Esther; van Vuurden, Dannis G; Vandertop, W Peter; Kaspers, Gertjan J L; Noske, David P; Wurdinger, Thomas

2013-02-01

142

The high-energy diffuse cosmic gamma-ray background radiation from blazars  

NASA Technical Reports Server (NTRS)

We predict the spectrum and flux of the high-energy diffuse cosmic gamma-ray background radiation produced by blazars. Our calculations are based on the Compton Observatory EGRET observations of high-energy gamma-rays from these objects, the Whipple observation of TeV gamma-rays from Mrk 421, and radio population studies of flat-spectrum radio sources. Our statistical analysis gives a result consistent with a linear correlation. We then use the radio luminosity function and redshift evolution to calculate the gamma-ray background. We find that blazars cannot account for the flux level or steep spectrum of the background observed by SAS 2 in the sub-GeV range, but could likely provide the dominant background component in the multi-GeV energy range and above. We predict a differential photon spectral index for this component of about 2 up to about 10 GeV. Above that energy, the spectrum should gradually steepen owing to pair production by interactions of the gamma-rays with intergalactic infrared photons. Using the calculations of this effect by Stecker et al. (1992), we estimate a spectral index of about 3.5 for energies above a TeV.

Stecker, F. W.; Salamon, M. H.; Malkan, M. A.

1993-01-01

143

Construction of accuracy-preserving surrogate for the eigenvalue radiation diffusion and/or transport problem  

SciTech Connect

The construction of surrogate models for high fidelity models is now considered an important objective in support of all engineering activities which require repeated execution of the simulation, such as verification studies, validation exercises, and uncertainty quantification. The surrogate must be computationally inexpensive to allow its repeated execution, and must be computationally accurate in order for its predictions to be credible. This manuscript introduces a new surrogate construction approach that reduces the dimensionality of the state solution via a range-finding algorithm from linear algebra. It then employs a proper orthogonal decomposition-like approach to solve for the reduced state. The algorithm provides an upper bound on the error resulting from the reduction. Different from the state-of-the-art, the new approach allows the user to define the desired accuracy a priori which controls the maximum allowable reduction. We demonstrate the utility of this approach using an eigenvalue radiation diffusion model, where the accuracy is selected to match machine precision. Results indicate that significant reduction is possible for typical reactor assembly models, which are currently considered expensive given the need to employ very fine mesh many group calculations to ensure the highest possible fidelity for the downstream core calculations. Given the potential for significant reduction in the computational cost, we believe it is possible to rethink the manner in which homogenization theory is currently employed in reactor design calculations. (authors)

Wang, C.; Abdel-Khalik, H. S. [Dept. of Nuclear Engineering, North Caroline State Univ., Raleigh, NC 27695 (United States)

2012-07-01

144

RADIATION SAFETY TRAINING MANUAL Radiation Safety Office  

E-print Network

RADIATION SAFETY TRAINING MANUAL Radiation Safety Office 130 DeSoto Street G-7 Parran with sources of ionizing radiation are required to be instructed in the basic principles of radiation protection and the potential risks of ionizing radiation. Radiation Safety Office personnel provide

Sibille, Etienne

145

Experimental measurements of a prototype high concentration Fresnel lens CPV module for the harvesting of diffuse solar radiation.  

PubMed

A prototype concentrator photovoltaic (CPV) module with high solar concentration, an added low-cost solar cell, and an adjoining multi-junction solar cell is fabricated and experimentally demonstrated. In the present CPV module, the low cost solar cell captures diffuse solar radiation penetrating the concentrator lens and the multi-junction cell captures concentrated direct solar radiation. On-sun test results show that the electricity generated by a Fresnel lens-based CPV module with an additional crystalline silicon solar cell is greater than that for a conventional CPV module by a factor of 1.44 when the mean ratio of diffuse normal irradiation to global normal irradiation at the module aperture is 0.4. Several fundamental optical characteristics are presented for the present module. PMID:24921997

Yamada, Noboru; Okamoto, Kazuya

2014-01-13

146

Boundary conditions for polarized radiative transfer with incident radiation  

NASA Astrophysics Data System (ADS)

Context. Polarized radiative transfer in the presence of scattering in spectral lines and/or in continua may be cast in a reduced form for six reduced components of the radiation field. In this formalism, the six components of the reduced source function are angle-independent quantities. It thus drastically reduces the storage requirement of numerical codes and it is very well suited to solving polarized non-local thermodynamic equilibrium radiative transfer problems in 3D media. Aims: This approach encounters a fundamental problem when the medium is illuminated by a polarized incident radiation, because there is a priori no way of relating the known (and measurable) Stokes parameters of the incident radiation to boundary conditions for the reduced equations. The origin of this problem is that there is no unique way of deriving the radiation-reduced components from its Stokes parameters (only the inverse operation is clearly defined). The method proposed here aims at enabling to work with arbitrary incident radiation field (polarized or unpolarized). Methods: In previous studies, an ad-hoc treatment of the boundary conditions, applied to cases where the incident radiation is unpolarized, has been used. In this paper, we show that it is possible to account for the incident radiation in a rigorous way without any assumption on its properties by expressing the radiation field as the sum of a directly transmitted radiation and of a diffuse radiation. This approach was first used by Chandrasekhar to solve the problem of diffuse reflection by planetary atmospheres illuminated by their host star. Results: The diffuse radiation field obeys a transfer equation with no incident radiation that may be solved in the reduced form. The first scattering of the incident radiation introduces primary creation terms in the six components of the reduced source function. Once the reduced polarized transfer problem is solved for the diffuse radiation field, its Stokes parameters can be computed. The full radiation field is then obtained by adding the directly transmitted radiation field computed in the Stokes formalism. Conclusions: In the case of an unpolarized incident radiation, the diffuse field approach allows us to validate the previously introduced ad-hoc expressions. The diffuse field approach however leads to more accurate computation of the source terms in the case where the incident radiation is anisotropic. It is the only possible approach when the incident radiation field is polarized. We perform numerical computations of test cases, showing that the emergent line-polarization may be significantly affected by the polarization of the incident radiation.

Faurobert, M.; Mili?, I.; Atanackovi?, O.

2013-11-01

147

Radiation receiver  

DOEpatents

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.

Hunt, Arlon J. (Oakland, CA)

1983-01-01

148

Results of nimotuzumab and vinorelbine, radiation and re-irradiation for diffuse pontine glioma in childhood.  

PubMed

Radiotherapy is the only treatment definitely indicated for diffuse pontine gliomas (DIPG). Findings on the role of EGFR signaling in the onset of childhood DIPG prompted the use of nimotuzumab, an anti-EGFR monoclonal antibody. Assuming a potential synergy with both radiotherapy and vinorelbine, a pilot phase 2 protocol was launched that combined nimotuzumab with concomitant radiation and vinorelbine. An amendment in July 2011 introduced re-irradiation at relapse. The primary endpoint for first-line treatment was objective response rate (CR + PR + SD) according to the RECIST. This report concerns the outcome of this strategy as a whole. Vinorelbine 20 mg/m(2) was administered weekly, with nimotuzumab 150 mg/m(2) in the first 12 weeks of treatment; radiotherapy was delivered from weeks 3 to 9, for a total dose of 54 Gy. Vinorelbine 25 mg/m(2) and nimotuzumab were given every other week thereafter until the tumor progressed or for up to 2 years. Re-irradiation consisted of 19.8 Gy, fractionated over 11 days. Baseline and latest MRIs were assessed blindly by an outside neuroradiologist. Twenty five children (mean age 7.4 years) were enrolled as of August 2009 (median follow-up 29 months). A response was observed in 24/25 patients (96 %). The nimotuzumab/vinorelbine combination was very well tolerated, with no acute side-effects. Eleven of 16 locally-relapsing patients were re-irradiated. One-year PFS and OS rates were 30 ± 10 % and 76 ± 9 %, respectively; 2-year OS was 27 ± 9 %; the median PFS and OS were 8.5 and 15 months, respectively. This strategy generated interesting results and warrants further investigation. PMID:24696052

Massimino, Maura; Biassoni, Veronica; Miceli, Rosalba; Schiavello, Elisabetta; Warmuth-Metz, Monika; Modena, Piergiorgio; Casanova, Michela; Pecori, Emilia; Giangaspero, Felice; Antonelli, Manila; Buttarelli, Francesca Romana; Potepan, Paolo; Pollo, Bianca; Nunziata, Raffaele; Spreafico, Filippo; Podda, Marta; Anichini, Andrea; Clerici, Carlo Alfredo; Sardi, Iacopo; De Cecco, Loris; Bode, Udo; Bach, Ferdinand; Gandola, Lorenza

2014-06-01

149

Radiation Fog  

NSDL National Science Digital Library

This module presents the physical processes and life cycle of radiation fog, including its preconditioning environment, initiation, growth, and dissipation. The processes include radiation (both solar and longwave), soil-atmosphere thermal interactions, turbulent mixing, the roles of condensation nuclei, and droplet settling. Each section includes a set of interactive questions based on the learning content presented. Tom Dulong of the National Weather Service Center Weather Service Unit (CWSU) in Longmont, Colorado is the Principal Science Advisor for this module, and Dr. Paul Croft, Meteorology Program Coordinator for Jackson State University, provided additional scientific review and guidance. The module's format was updated and republished on May 20, 2009.

2014-09-14

150

Appendix G. Radiation Appendix G. Radiation  

E-print Network

Appendix G. Radiation #12;#12;Appendix G. Radiation This appendix presents basic facts about radiation. The information is intended to be a basis for un- derstanding the potential doses associated of radiation and its effects on the environment and biological systems. Radiation comes from natural and human

Pennycook, Steve

151

Radiation Emergencies  

MedlinePLUS

... enough, it can cause premature aging or even death. Although there are no guarantees of safety during a radiation emergency, you can take actions to protect yourself. You should have a disaster plan. Being prepared can help reduce fear, anxiety and losses. Centers for Disease Control and ...

152

Radiation Activities  

NSDL National Science Digital Library

This page presents activities related to radiation from the Science & Engineering in the Lives of Students project. Activities include Roof Albedo, Speed Melting, and Tricks with a TV Remote. Each activity includes a detailed description, list of the materials needed, science concepts covered, and reflection questions.

2013-07-17

153

RADIATION PNEUMONITIS  

Microsoft Academic Search

From a review of the literature, it may be concluded that, since the ; recognition of radiation pneumonitis in 1922, the clinical features of this ; condition have been clarified, the radiographic patterns have been defined, the ; pathologic lesions have been described, and the effects of treatment have been ; appraised. ln addition, the incidence has been revealed and

1963-01-01

154

RADIATION DETECTORS  

Microsoft Academic Search

Three new and important lines of development in nuclear radiation ; detection and measurement are presented. Two of these developments, spark ; chambers and image-intensifier\\/ luminescent-chamber systems, enable pictures or ; other records of nuclear particle tracks to be obtained with a much higher degree ; of time resolution than is possible with existing techniques, e g., with cloud ;

W. Abson

1962-01-01

155

Radiation Pressure  

Microsoft Academic Search

ON p. 515 of your issue of September 22 I stated that there is a retarding force on the earth as it moves along its orbit amounting in all to about 20 kgm. The calculation was made on the supposition that the earth is a full radiator of uniform temperature. I have found on revising the calculation that there was

J. H. Poynting

1904-01-01

156

On equivalent diffuse conditions for an internal layer in multislab atmospheric radiation  

Microsoft Academic Search

This paper reports on new discrete ordinates conditions for efficiently solving a set of multislab atmospheric radiation problems characterized by an optically stationary internal layer, i.e. an internal layer whose optical (absorption\\/scattering) properties and optical thickness do not change from one problem to another in the set. The discrete ordinates conditions reported here are founded in a recently developed spectral

Marcos Pimenta de Abreu

2006-01-01

157

Hybrid model of light propagation in random media based on the time-dependent radiative transfer and diffusion equations  

NASA Astrophysics Data System (ADS)

Numerical modeling of light propagation in random media has been an important issue for biomedical imaging, including diffuse optical tomography (DOT). For high resolution DOT, accurate and fast computation of light propagation in biological tissue is desirable. This paper proposes a space-time hybrid model for numerical modeling based on the radiative transfer and diffusion equations (RTE and DE, respectively) in random media under refractive-index mismatching. In the proposed model, the RTE and DE regions are separated into space and time by using a crossover length and the time from the ballistic regime to the diffusive regime, ?DA~10/?t? and tDA~20/v?t? where ?t? and v represent a reduced transport coefficient and light velocity, respectively. The present model succeeds in describing light propagation accurately and reduces computational load by a quarter compared with full computation of the RTE.

Fujii, Hiroyuki; Okawa, Shinpei; Yamada, Yukio; Hoshi, Yoko

2014-11-01

158

Second order time evolution of the multigroup diffusion and P{sub 1} equations for radiation transport  

SciTech Connect

Highlights: {yields} An existing multigroup transport algorithm is extended to be second-order in time. {yields} A new algorithm is presented that does not require a grey acceleration solution. {yields} The two algorithms are tested with 2D, multi-material problems. {yields} The two algorithms have comparable computational requirements. - Abstract: An existing solution method for solving the multigroup radiation equations, linear multifrequency-grey acceleration, is here extended to be second order in time. This method works for simple diffusion and for flux-limited diffusion, with or without material conduction. A new method is developed that does not require the solution of an averaged grey transport equation. It is effective solving both the diffusion and P{sub 1} forms of the transport equation. Two dimensional, multi-material test problems are used to compare the solution methods.

Olson, Gordon L., E-mail: olson99@tds.net [Computer and Computational Sciences Division (CCS-2), Los Alamos National Laboratory, 5 Foxglove Circle, Madison, WI 53717 (United States)

2011-08-20

159

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

NASA Astrophysics Data System (ADS)

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.

Ragusa, Jean C.

2015-01-01

160

Quantitative monitoring of radiation induced skin toxicities in nude mice using optical biomarkers measured from diffuse optical reflectance spectroscopy  

PubMed Central

Monitoring the onset of erythema following external beam radiation therapy has the potential to offer a means of managing skin toxicities via biological targeted agents – prior to full progression. However, current skin toxicity scoring systems are subjective and provide at best a qualitative evaluation. Here, we investigate the potential of diffuse optical spectroscopy (DOS) to provide quantitative metrics for scoring skin toxicity. A DOS fiberoptic reflectance probe was used to collect white light spectra at two probing depths using two short fixed source-collector pairs with optical probing depths sensitive to the skin surface. The acquired spectra were fit to a diffusion theory model of light transport in tissue to extract optical biomarkers (hemoglobin concentration, oxygen saturation, scattering power and slope) from superficial skin layers of nude mice, which were subjected to erythema inducing doses of ionizing radiation. A statistically significant increase in oxygenated hemoglobin (p < 0.0016) was found in the skin post-irradiation – confirming previous reports. More interesting, we observed for the first time that the spectral scattering parameters, A (p = 0.026) and k (p = 0.011), were an indicator of erythema at day 6 and could potentially serve as an early detection optical biomarker of skin toxicity. Our data suggests that reflectance DOS may be employed to provide quantitative assessment of skin toxicities following curative doses of external beam radiation. PMID:24876997

Yohan, Darren; Kim, Anthony; Korpela, Elina; Liu, Stanley; Niu, Carolyn; Wilson, Brian C; Chin, Lee CL

2014-01-01

161

Sound Radiation from Cylindrical Radiators  

NSDL National Science Digital Library

The following animations illustrate the radiation of sound waves from a vibrating source in 2-D. The source is a long cylinder which is oscillating in the radial direction only (all vibrations along the length of the cylinder are ignored). In particular, the animations show the vibration of the cylinder in its various modes and the resulting particle displacements of the surrounding fluid.

Russell, Dan

162

Acute Radiation Syndrome  

MedlinePLUS

... Tools CDC Response, Japan 2011 Specific Hazards 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 ...

163

Gallbladder Cancer: Radiation Therapy  

MedlinePLUS

... gallbladder cancer Next Topic Chemotherapy for gallbladder cancer Radiation therapy for gallbladder cancer Radiation therapy uses high- ... higher dose to the cancer areas. Uses of radiation therapy Radiation therapy can be used in several ...

164

Radiation Oncology Treatment Team  

MedlinePLUS

... Prostate Skin Upper GI Latest Research 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 ...

165

Calculate Your Radiation Dose  

MedlinePLUS

... Ionizing & Non-Ionizing Radiation Understanding Radiation: Calculate Your Radiation Dose Health Effects Main Page Exposure Pathways Calculate ... of the US do you live in? Internal radiation (in your body): From food and water, (e. ...

166

Radiation Belts  

NSDL National Science Digital Library

The inner radiation belt, discovered by Van Allen, consists of very energetic protons, a by-product of collisions of cosmic ray ions with atoms in the atmosphere. This site provides information on the behavior and relative energies of the particles in the belts. Historic information about the discoveries made in 1958 by a University of Iowa team, headed by James Van Allen, is cited as well.

Stern, David

167

SMM detection of diffuse Galactic 511 keV annihilation radiation  

NASA Technical Reports Server (NTRS)

Observations of the 511 keV annihilation line from the vicinity of the Galactic center from October to February for 1980/1981, 1981/1982, 1982/1983, 1984/1985, and 1985/1986 are presented. The measurements were made with the gamma-ray spectrometer on the SMM. The design of the instrument and some of its properties used in the analysis are described, and the methods used for accumulating, fitting, and analyzing the data are outlined. It is shown how the Galactic 511 keV line was separated from the intense and variable background observed in orbit. The SMM observations are compared with previous measurements of annihilation radiation from the Galactic center region, and the astrophysical implications are discussed. It is argued that most of the measurements made to date suggest the presence of an extended Galactic source of annihilation radiation.

Share, G. H.; Kinzer, R. L.; Kurfess, J. D.; Messina, D. C.; Purcell, W. R.

1988-01-01

168

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

SciTech Connect

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.

Janssens, Geert O., E-mail: g.janssens@rther.umcn.nl [Department of Radiation Oncology, Radboud University Nijmegen Medical Centre, Nijmegen (Netherlands); Jansen, Marc H. [Pediatric Oncology/Hematology, VU University Medical Center, Amsterdam (Netherlands)] [Pediatric Oncology/Hematology, VU University Medical Center, Amsterdam (Netherlands); Lauwers, Selmer J. [Department of Radiation Oncology, Radboud University Nijmegen Medical Centre, Nijmegen (Netherlands)] [Department of Radiation Oncology, Radboud University Nijmegen Medical Centre, Nijmegen (Netherlands); Nowak, Peter J. [Department of Radiation Oncology, Erasmus Medical Centre, Rotterdam (Netherlands)] [Department of Radiation Oncology, Erasmus Medical Centre, Rotterdam (Netherlands); Oldenburger, Foppe R. [Department of Radiation Oncology, Academic Medical Centre, Amsterdam (Netherlands)] [Department of Radiation Oncology, Academic Medical Centre, Amsterdam (Netherlands); Bouffet, Eric [Department of Hematology/Oncology, The Hospital for Sick Children, University of Toronto, Toronto (Canada)] [Department of Hematology/Oncology, The Hospital for Sick Children, University of Toronto, Toronto (Canada); Saran, Frank [Department of Pediatric Oncology, The Royal Marsden NHS Foundation Trust, Sutton (United Kingdom)] [Department of Pediatric Oncology, The Royal Marsden NHS Foundation Trust, Sutton (United Kingdom); Kamphuis-van Ulzen, Karin [Department of Radiology, Radboud University Nijmegen Medical Centre, Nijmegen (Netherlands)] [Department of Radiology, Radboud University Nijmegen Medical Centre, Nijmegen (Netherlands); Lindert, Erik J. van [Department of Neurosurgery, Radboud University Nijmegen Medical Centre, Nijmegen (Netherlands)] [Department of Neurosurgery, Radboud University Nijmegen Medical Centre, Nijmegen (Netherlands); Schieving, Jolanda H. [Department of Neurology, Radboud University Nijmegen Medical Centre, Nijmegen (Netherlands)] [Department of Neurology, Radboud University Nijmegen Medical Centre, Nijmegen (Netherlands); Boterberg, Tom [Department of Radiation Oncology, Ghent University Hospital, Ghent (Belgium)] [Department of Radiation Oncology, Ghent University Hospital, Ghent (Belgium); Kaspers, Gertjan J. [Pediatric Oncology/Hematology, VU University Medical Center, Amsterdam (Netherlands)] [Pediatric Oncology/Hematology, VU University Medical Center, Amsterdam (Netherlands); Span, Paul N.; Kaanders, Johannes H. [Department of Radiation Oncology, Radboud University Nijmegen Medical Centre, Nijmegen (Netherlands)] [Department of Radiation Oncology, Radboud University Nijmegen Medical Centre, Nijmegen (Netherlands); Gidding, Corrie E. [Department of Pediatric Oncology, Radboud University Nijmegen Medical Centre, Nijmegen (Netherlands)] [Department of Pediatric Oncology, Radboud University Nijmegen Medical Centre, Nijmegen (Netherlands); Hargrave, Darren [Department of Oncology, Great Ormond Street Hospital, London (United Kingdom)] [Department of Oncology, Great Ormond Street Hospital, London (United Kingdom)

2013-02-01

169

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

E-print Network

Radiation Predicted by Equation 4. 37 Using the Horizontal, East, and West MPA Sensors (4/7/94). 58 Page Figure 5. 4: Uncorrected MPA Calculated Beam VS NIP Beam with Artificial Horizon (9/18/94). . . . . . . 59 Figure 5. 5: Small Number Division... in the Current Work? . 16 CHAPTER III METHODOLOGY . . . 17 3. 1 Experimental Setup. . . . . . 3. 2 Test Bench Description. 3. 3 Sensor Calibration. . . . . 17 . 17 . . . . 18 3. 4 Day to Day Operations and Weekly Polling . . 3. 5 Test Bench Location...

Munger, Bryce Kirtley

1997-01-01

170

Solar radiation calibration facility.  

NASA Technical Reports Server (NTRS)

A recently completed calibration facility for the NASA Mississippi Test Site is described. It combines the spectrum of water cooled long arc xenon radiation sources with the integration sphere concept covered by a special barium sulfate diffusely reflecting paint. The sphere is six feet in diameter and completely encompasses the four xenon sources (2.5 kW each) and the five pyranometers under calibration. The sources are contained within the base of the central pedestal and allow the radiation to be emitted into the lower hemisphere. Only through diffuse reflection and multiple scattering is the radiation finally incident upon the test zone, which is in the equatorial plane of the sphere on the top of the pedestal. The sphere is temperature controlled.

Hershey, T. L.

1972-01-01

171

A faster algorithm for smoothed particle hydrodynamics with radiative transfer in the flux-limited diffusion approximation  

E-print Network

We describe a new, faster implicit algorithm for solving the radiation hydrodynamics equations in the flux-limited diffusion approximation for smoothed particle hydrodynamics. This improves on the method elucidated in Whitehouse & Bate by using a Gauss-Seidel iterative method rather than iterating over the exchange of energy between pairs of particles. The new algorithm is typically many thousands of times faster than the old one, which will enable more complex problems to be solved. The new algorithm is tested using the same tests performed by Turner & Stone for ZEUS-2D, and repeated by Whitehouse & Bate.

Stuart C. Whitehouse; Matthew R. Bate; Joe J. Monaghan

2005-09-28

172

A faster algorithm for smoothed particle hydrodynamics with radiative transfer in the flux-limited diffusion approximation  

E-print Network

We describe a new, faster implicit algorithm for solving the radiation hydrodynamics equations in the flux-limited diffusion approximation for smoothed particle hydrodynamics. This improves on the method elucidated in Whitehouse & Bate by using a Gauss-Seidel iterative method rather than iterating over the exchange of energy between pairs of particles. The new algorithm is typically many thousands of times faster than the old one, which will enable more complex problems to be solved. The new algorithm is tested using the same tests performed by Turner & Stone for ZEUS-2D, and repeated by Whitehouse & Bate.

Whitehouse, S C; Monaghan, J J; Whitehouse, Stuart C.; Bate, Matthew R.; Monaghan, Joe J.

2005-01-01

173

A faster algorithm for smoothed particle hydrodynamics with radiative transfer in the flux-limited diffusion approximation  

NASA Astrophysics Data System (ADS)

We describe a new, faster implicit algorithm for solving the radiation hydrodynamics equations in the flux-limited diffusion approximation for smoothed particle hydrodynamics. This improves on the method elucidated in Whitehouse and Bate by using a Gauss-Seidel iterative method rather than iterating over the exchange of energy between pairs of particles. The new algorithm is typically many thousands of times faster than the old one, which will enable more complex problems to be solved. The new algorithm is tested using the same tests performed by Turner and Stone for ZEUS-2D, and repeated by Whitehouse and Bate.

Whitehouse, Stuart C.; Bate, Matthew R.; Monaghan, Joe J.

2005-12-01

174

Fundamental Radiation Concepts  

E-print Network

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

Slatton, Clint

175

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

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.

Lopez Guerra, Jose Luis [Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, TX (United States) [Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, TX (United States); Department of Radiation Oncology, Hospitales Universitarios Virgen del Rocio, Seville (Spain); Gomez, Daniel, E-mail: dgomez@mdanderson.org [Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, TX (United States)] [Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, TX (United States); Zhuang Yan; Levy, Lawrence B. [Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, TX (United States)] [Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, TX (United States); Eapen, George [Department of Pulmonary Medicine, University of Texas MD Anderson Cancer Center, Houston, TX (United States)] [Department of Pulmonary Medicine, University of Texas MD Anderson Cancer Center, Houston, TX (United States); Liu Hongmei; Mohan, Radhe; Komaki, Ritsuko; Cox, James D.; Liao Zhongxing [Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, TX (United States)] [Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, TX (United States)

2012-08-01

176

Acquisition of reproducible transmission near-infrared (NIR) spectra of solid samples with inconsistent shapes by irradiation with isotropically diffused radiation using polytetrafluoroethylene (PTFE) beads.  

PubMed

A bead-incorporated transmission scheme (BITS) has been demonstrated for collecting reproducible transmission near-infrared (NIR) spectra of samples with inconsistent shapes. Isotropically diffused NIR radiation was applied around a sample and the surrounding radiation was allowed to interact homogeneously with the sample for transmission measurement. Samples were packed in 1.40 mm polytetrafluoroethylene (PTFE) beads, ideal diffusers without NIR absorption, and then transmission spectra were collected by illuminating the sample-containing beads using NIR radiation. When collimated radiation was directly applied, a small portion of the non-fully diffused radiation (NFDR) propagated through the void space of the packing and eventually degraded the reproducibility. Pre-diffused radiation was introduced by placing an additional PTFE disk in front of the packing to diminish NFDR, which produced more reproducible spectral features. The proposed scheme was evaluated by analyzing two different solid samples: density determination for individual polyethylene (PE) pellets and identification of mining locality for tourmalines. Because spectral collection was reproducible, the use of the spectrum acquired from one PE pellet was sufficient to accurately determine the density of nine other pellets with different shapes. The differentiation of tourmalines, which are even more dissimilar in appearance, according to their mining locality was also feasible with the help of the scheme. PMID:24818217

Lee, Jinah; Duy, Pham Khac; Yoon, Jihye; Chung, Hoeil

2014-06-21

177

The Effects of Thermal Radiation and Heat Source on an Unsteady MHD Free Convection Flow Past an Infinite Vertical Plate with Thermal Diffusion and Diffusion Thermo  

NASA Astrophysics Data System (ADS)

In this paper, we investigate the effects of thermal radiation and heat source on an unsteady magnetohydrodynamic free convection flow past an infinite vertical plate in a porous medium in presence of thermal diffusion and diffusion thermo. The dimensionless governing equations are solved numerically using finite element method. The numerical results for some special cases were compared with Shanker et al. and were found to be in good agreement. Graphical results for velocity, temperature and concentration profiles based on the numerical solutions are presented and discussed within the boundary layer. And also the skin-friction at the plate due to velocity field, rate of heat transfer due to temperature field and mass transfer due to concentration field are obtained in non-dimensional form. The effects of the different physical flow parameters on these respective flow fields are discussed through graphs and results are physically interpreted.

Raju, R. S.; Sudhakar, K.; Rangamma, M.

2013-04-01

178

Shortwave Radiation  

NASA Technical Reports Server (NTRS)

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.

Klassen, Steve; Bugbee, Bruce

2005-01-01

179

Radiating gravastars  

SciTech Connect

Considering a Vaidya exterior spacetime, we study dynamical models of prototype gravastars, made of an infinitely thin spherical shell of a perfect fluid with the equation of state p = ?, enclosing an interior de Sitter spacetime. We show explicitly that the final output can be a black hole, an unstable gravastar, a stable gravastar or a 'bounded excursion' gravastar, depending on how the mass of the shell evolves in time, the cosmological constant and the initial position of the dynamical shell. This work presents, for the first time in the literature, a gravastar that emits radiation.

Chan, R. [Coordenação de Astronomia e Astrofísica, Observatório Nacional, Rua General José Cristino, 77, São Cristóvão 20921-400, Rio de Janeiro, RJ (Brazil); Silva, M.F.A. da [Departamento de Física Teórica, Instituto de Física, Universidade do Estado do Rio de Janeiro, Rua São Francisco Xavier 524, Maracanã 20550-900, Rio de Janeiro - RJ (Brazil); Rocha, Jaime F. Villas da [Instituto de Biociências, Departamento de Ciências Naturais, Universidade Federal do Estado do Rio de Janeiro, Av. Pasteur 458, Urca, CEP 22290-240, Rio de Janeiro, RJ (Brazil); Wang, Anzhong, E-mail: chan@on.br, E-mail: mfasnic@gmail.com, E-mail: jfvroch@pq.cnpq.br, E-mail: anzhong_wang@baylor.edu [GCAP-CASPER, Department of Physics, Baylor University, Waco, TX 76798 (United States)

2011-10-01

180

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

SciTech Connect

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.

Evans, Thomas M [ORNL] [ORNL; Mosher, Scott W [ORNL] [ORNL; Slattery, Stuart [University of Wisconsin, Madison] [University of Wisconsin, Madison

2014-01-01

181

The radiation pattern of Auroral Kilometric Radiation  

NASA Astrophysics Data System (ADS)

The radiation pattern has been determined on the basis of the comparative analysis of auroral kilometric radiation (AKR) received in the space-diversity mode simultaneous by two satellites, Interball-2 and Polar. The radiation propagates in a cone with an opening angle ~± 25° and the axis aligned with the local magnetic field. The results confirm the theoretical estimates that the source boundaries play a significant role in the generation of the auroral kilometric radiation and in the formation of the radiation pattern.

Romantsova, T. V.; Mogilevsky, M. M.; Hanasz, J.

2013-09-01

182

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

NASA Technical Reports Server (NTRS)

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.

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

1999-01-01

183

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

SciTech Connect

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.

Yu, Jeong Il; Nam, Heerim [Department of Radiation Oncology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul (Korea, Republic of); Ahn, Yong Chan, E-mail: ahnyc@skku.ed [Department of Radiation Oncology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul (Korea, Republic of); Kim, Won Seog; Park, Keunchil; Kim, Seok Jin [Division of Hematology-Oncology, Department of Internal Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul (Korea, Republic of)

2010-10-01

184

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

NASA Technical Reports Server (NTRS)

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.

Plante, Ianik; Wu, Honglu

2014-01-01

185

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

SciTech Connect

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.

Shestakov, A I; Offner, S R

2006-09-21

186

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

SciTech Connect

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.

Chapman, Christopher H., E-mail: chchap@umich.edu [Department of Radiation Oncology, University of Michigan Medical School, Ann Arbor, MI (United States); Nagesh, Vijaya [Department of Radiation Oncology, University of Michigan Medical School, Ann Arbor, MI (United States); Sundgren, Pia C. [Department of Radiology, University of Michigan Medical School, Ann Arbor, MI (United States); Department of Radiology, Skane University Hospital, Lund (Sweden); Buchtel, Henry [Department of Psychiatry, University of Michigan Medical School, Ann Arbor, MI (United States); Veterans Affairs Ann Arbor Healthcare System, Ann Arbor, MI (United States); Chenevert, Thomas L. [Department of Radiology, University of Michigan Medical School, Ann Arbor, MI (United States); Junck, Larry [Department of Neurology, University of Michigan Medical School, Ann Arbor, MI (United States); Lawrence, Theodore S.; Tsien, Christina I. [Department of Radiation Oncology, University of Michigan Medical School, Ann Arbor, MI (United States); Cao, Yue [Department of Radiation Oncology, University of Michigan Medical School, Ann Arbor, MI (United States); Department of Radiology, University of Michigan Medical School, Ann Arbor, MI (United States)

2012-04-01

187

Adaptors for radiation detectors  

DOEpatents

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.

Livesay, Ronald Jason

2014-04-22

188

Radiation Insulation  

NASA Technical Reports Server (NTRS)

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.

1993-01-01

189

Radiation Insulation  

NASA Technical Reports Server (NTRS)

The Apollo and subsequent spacecraft have had highly effective radiation barriers; made of aluminized polymer film, they bar or let in heat to maintain consistent temperatures inside. Tech 2000, formerly Quantum International Corporation used the NASA technology in its insulating materials, Super "Q" Radiant Barrier, for home, industry and mobile applications. The insulation combines industrial aluminum foil overlaid around a core of another material, usually propylene or mylar. The outer layer reflects up to 97 percent of heat; the central layer creates a thermal break in the structure and thus allows low radiant energy emission. The Quantum Cool Wall, used in cars and trucks, takes up little space while providing superior insulation, thus reducing spoilage and costs. The panels can also dampen sound and engine, exhaust and solar heat.

1995-01-01

190

Radiation Safety September 2013  

E-print Network

Radiation Safety Manual September 2013 Office of Environment, Health & Safety #12;RADIATION SAFETY of ionizing radiation as a valuable tool to extend fundamental knowledge. These activities are an important of radiation-producing machines and radioactive materials attests to the success of its radiation safety

California at Irvine, University of

191

Radiation Processing -an overview  

E-print Network

· - not making something radioactive Radioactive · Substance emitting radiation Ionising Radiation · Radiation Different microorganisms have different resistances to radiation #12;36 Sterilization Definition1 Radiation Processing - an overview Arne Miller Risø High Dose Reference Laboratory Risø DTU DK

192

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

NASA Technical Reports Server (NTRS)

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.

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

1992-01-01

193

Non-diffusive resonant acceleration of electrons in the radiation belts  

NASA Astrophysics Data System (ADS)

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.

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

2012-12-01

194

Rhabdomyosarcoma: Radiation Therapy  

MedlinePLUS

... dose chemotherapy and stem cell transplants for rhabdomyosarcoma Radiation therapy for rhabdomyosarcoma Radiation therapy uses high-energy ... so they won’t move during treatment. Newer radiation techniques Some newer techniques can help doctors aim ...

195

Radiation Protection: Basic Information  

MedlinePLUS

... informs the public about radiation topics, such as radon in homes, through brochures, public service announcements, hotlines, ... and radiation protection issues testing their homes for radon responsibly handling and disposing of radiation-containing consumer ...

196

Types of Radiation Emergencies  

MedlinePLUS

... Radiation Disasters Public Health Planning for Radiological and Nuclear Terrorism Radiation Basics Made Simple Radiological Terrorism: Just in Time ... intense pulse of heat, light, air pressure, and radiation. Nuclear explosions produce fallout (radioactive materials that can be ...

197

Radiation from Relativistic Jets  

NASA Technical Reports Server (NTRS)

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.

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

198

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

NASA Astrophysics Data System (ADS)

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.

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

2011-03-01

199

[Neurotoxicity of radiation].  

PubMed

Abstract It is well-known that the central nervous system is thoroughly resistant to ionizing radiation as high-dose radiation exposure is required for causing neuronal death. In contrast, recent studies have revealed that the hippocampus, which could be the main organ involved in disorder of higher brain functions after radiation therapy, contains radiation-sensitive cell fractions. In this paper, the basics of radiation effects and the molecular mechanism of neurotoxicity of radiation have been reviewed and discussed. PMID:25585436

Suzuki, Keiji

2015-01-01

200

The role of radiation therapy in the treatment of stage I-II diffuse large B-cell lymphoma.  

PubMed

The role of radiation therapy (RT) in the treatment of Stage I-II diffuse large B cell lymphoma (DLBCL) is controversial: consolidation RT improves local control, but does this translate into an overall survival benefit? The paucity of randomized clinical trials means that the debate surrounding the benefit of consolidation RT remains unresolved. To date, the published literature demonstrates that consolidation RT has dual advantages in patients stage I-II DLBCL: (1) to improve local control and progression-free survival, and (2) to spare additional cycles of chemotherapy in patient with favourable-risk disease. Critics of consolidation RT are often influenced by the profile of late toxicities that are associated with outdated RT techniques. In the current era of molecular-based targeted therapy and functional imaging, prospective randomized studies are required to answer this research question and to investigate risk-adapted treatment strategies for patients with stage I-II DLBCL. PMID:23901002

Campbell, Belinda A

2013-09-01

201

Slip effects on the unsteady radiative MHD free convection flow over a moving plate with mass diffusion and heat source  

NASA Astrophysics Data System (ADS)

General solutions for the dimensionless velocity corresponding to the unsteady radiative MHD free convection flow of an incompressible viscous fluid over a moving plate with mass diffusion and slip/no-slip conditions are established by combining the Laplace transform technique with the homotopy perturbation method. Internal dissipation is neglected but the heat absorption/generation and Soret effects are considered. The results that have been obtained can generate exact solutions for any motion with technical relevance of this type. Three special cases are considered and some known results from the literature are recovered. Influence of slip parameter and of some pertinent parameters on the fluid motion is graphically underlined and discussed in the case of the uniform velocity of the plate. The required time to reach the steady state for motions due to sine and cosine oscillations of the plate is also determined.

Fetecau, Constantin; Vieru, Dumitru; Fetecau, Corina; Pop, Ioan

2015-01-01

202

Solar radiation on inclined surfaces  

NASA Astrophysics Data System (ADS)

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.

1980-05-01

203

Radiation biology and radiation protection.  

PubMed

For protection purposes, the biological effects of radiation are separated into stochastic effects (cancer, hereditary effects) presumed to be unicellular in origin, and tissue reactions due to injury in populations of cells. The latter are deterministic effects, renamed 'tissue reactions' in the 2007 Recommendations of the International Commission on Radiological Protection because of the increasing evidence of the ability to modify responses after irradiation. Tissue reactions become manifest either early or late after doses above a threshold dose, which is the basis for recommended dose limits for avoiding such effects. Latency time before manifestation is related to cell turnover rates, and tissue proliferative and structural organisation. Threshold doses have been defined for practical purposes at 1% incidence of an effect. In general, threshold doses are lower for longer follow-up times because of the slow progression of injury before manifestation. Radiosensitive individuals in the population may contribute to low threshold doses, and in the future, threshold doses may be increased by the use of various biological response modifiers post irradiation for reducing injury. Threshold doses would be expected to be higher for fractionated or protracted doses, unless doses below the threshold dose only cause single-hit-type events that are not modified by repair/recovery phenomena, or if different mechanisms of injury are involved at low and high doses. PMID:23089005

Hendry, J H

2012-01-01

204

Interaction of ring current and radiation belt protons with ducted plasmaspheric hiss. 1: Diffusion coefficients and timescales  

NASA Technical Reports Server (NTRS)

Protons that are convected into the inner magnetosphere in response to enhanced magnetic activity can resonate with ducted plasmaspheric hiss in the outer plasmasphere via an anomalous Doppler-shifted cyclotron resonance. Plasmaspheric hiss is a right-hand-polarized electromagnetic emission that is observed to fill the plasmasphere on a routine basis. When plasmaspheric hiss is confined within field-aligned ducts or guided along density gradients, wave normal angles remain largely below 45 deg. This allows resonant interactions with ions at typical ring current and radiation belt energies to take place. Such field-aligned ducts have been observed both within the plasmasphere and in regions outside of the plasmasphere. Wave intensities are estimated using statistical information from studies of detached plasma regions. Diffusion coefficients are presented for a range of L shells and proton energies for a fixed wave distribution. Harmonic resonances in the range N = +/-100 are considered in order to include interactions between hiss at 100 Hz to 2 kHz frequencies, and protons in the energy range between approximately 10 keV and 1000 keV. Diffusion timescales are estimated to be of the order of tens of days and comparable to or shorter than lifetimes for Coulomb decay and charge exchange losses over most of the energy and spatial ranges of interest.

Kozyra, J. U.; Rasmussen, C. E.; Miller, R. H.; Lyons, L. R.

1994-01-01

205

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

NASA Technical Reports Server (NTRS)

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.

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

1993-01-01

206

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

SciTech Connect

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.

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

2010-10-28

207

RADIATION HYBRID MAPPING  

Technology Transfer Automated Retrieval System (TEKTRAN)

Radiation hybrid maps are physical maps of genomes that provide an alternative to traditional genetic maps. These radiation hybrid maps have two important advantages over genetic maps. First, distances on a radiation hybrid map are determined by the frequency of radiation-induced breaks between mark...

208

Radiation detection and measurement  

Microsoft Academic Search

Introductory material covers radiation sources, radiation interactions, general properties of radiation detectors, and counting statistics and error prediction. This is followed by detailed sections on gas-filled detectors, scintillation counters, semiconductor detectors, neutron detectors and spectroscopy, detector electronics and pulse processing, and miscellaneous radiation detectors and applications.

Glenn F. Knoll

1979-01-01

209

Handbook of radiation effects  

Microsoft Academic Search

This book emphasizes radiation effects on solid state devices from exposure to the types of radiation found outside the atmosphere (in space, or in the vicinity of an exploding nuclear device). It contains a basic study of radiation shielding of payload components for payloads in space and specifically covers radiation effects on minority and majority carriers, optical media and organic

A. Holmes-Siedle; L. Adams

1993-01-01

210

Radiation and People  

ERIC Educational Resources Information Center

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)

Freilich, Florence G.

1970-01-01

211

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

SciTech Connect

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.

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

212

Pure and gravitational radiation  

E-print Network

The well-known treatment of asymptotically flat vacuum fields is adapted to pure radiation fields. In this approach we find a natural normalization of the radiation null vector. The energy balance at null infinity shows that the mass loss results from a linear superposition of the pure and the gravitational radiation parts. By transformation to Bondi-Sachs coordinates the Kinnersley photon rocket is found to be the only axisymmetric Robinson-Trautman pure radiation solution without gravitational radiation.

U. von der Goenna; D. Kramer

1997-11-03

213

Nonthermal effects on microwave radiation on ionic diffusion in ionic crystalline ceramics  

Microsoft Academic Search

Summary form only given, as follows. Numerous claims have been made of observations that microwave heating of ceramics promotes faster processing or solid state reactions (e.g., sintering, bonding, tracer ion diffusion) than conventional furnace heating. These claims are controversial due to the absence of a verifiable theoretical explanation as well as questions on the interpretation of sample temperature measurements obtained

S. A. Freeman; J. H. Booske; R. F. Cooper

1995-01-01

214

Integrating structural and diffusion MR information for optic radiation localisation in focal epilepsy patients  

Microsoft Academic Search

Current state of the art neurosurgical systems do not exploit the complementary information provided by structural and diffusion MRI when aligning pre-operative and intra-operative images. We propose a multivariate registration scheme where structural and fractional anisotropy data are combined in a single similarity measure. We formulate the normalised mutual information expression for the multichannel scheme and compute its analytical derivative.

Pankaj Daga; Gavin Winston; Marc Modat; M. Jorge Cardoso; Jason Stretton; Mark Symms; Andrew W. McEvoy; David Hawkes; John Duncan; Sebastien Ourselin

2011-01-01

215

Radial diffusion in Saturn's radiation belts - A modeling analysis assuming satellite and ring E absorption  

NASA Astrophysics Data System (ADS)

A modeling analysis is carried out of six experimental phase space density profiles for nearly equatorially mirroring protons using methods based on the approach of Thomsen et al. (1977). The form of the time-averaged radial diffusion coefficient D(L) that gives an optimal fit to the experimental profiles is determined under the assumption that simple satellite plus Ring E absorption of inwardly diffusing particles and steady-state radial diffusion are the dominant physical processes affecting the proton data in the L range that is modeled. An extension of the single-satellite model employed by Thomsen et al. to a model that includes multisatellite and ring absorption is described, and the procedures adopted for estimating characteristic satellite and ring absorption times are defined. The results obtained in applying three representative solid-body absorption models to evaluate D(L) in the range where L is between 4 and 16 are reported, and a study is made of the sensitivity of the preferred amplitude and L dependence for D(L) to the assumed model parameters. The inferred form of D(L) is then compared with that which would be predicted if various proposed physical mechanisms for driving magnetospheric radial diffusion are operative at Saturn.

Hood, L. L.

1983-02-01

216

Difference Between IR Radiation Spectra of Ethanol in Free Diffusion Combustion Regime and Regime Influenced by an Air Flow in Modeling of a Fire Tornado  

NASA Astrophysics Data System (ADS)

Results of experimental investigations of liquid fuel combustion in the regime of a twisted jet (model of a fire tornado) are presented. Flame radiation spectra were registered. In the chosen spectral range of registration (2.2-4.8 ?m), six spectral intervals were clearly traced in which the main portion of radiated energy was concentrated. Using the ratio of the sums of spectral intensities in the vicinities of the 6th and 3rd maxima, we successfully distinguished the regimes of modeled fire tornado and free diffusion fuel combustion.

Sherstobitov, M. V.; Tsvyk, R. Sh.

2013-06-01

217

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

NASA Technical Reports Server (NTRS)

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.

Kniffen, D. A.; Fichtel, C.

1981-01-01

218

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

NASA Technical Reports Server (NTRS)

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.

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

1974-01-01

219

Influence of Extraterrestrial Radiation on Radiation Portal Monitors  

Microsoft Academic Search

Cosmic radiation and solar flares can be a major source of background radiation at the Earth's surface. This paper examines the relationship between extraterrestrial radiation and the detectable background in radiation portal monitors used for homeland security applications. Background radiation data from 13 radiation portal monitor facilities are examined and compared against external sources of data related to extraterrestrial radiation,

Paul E. Keller; Richard T. Kouzes

2009-01-01

220

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

NASA Technical Reports Server (NTRS)

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.

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

1981-01-01

221

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

SciTech Connect

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.

Selesnick, R.S.; Stone, E.C. (California Inst. of Tech., Pasadena (USA))

1991-04-01

222

Measurement of atmospheric and diffuse radiation using a time-of-flight telescope  

SciTech Connect

A time-of-flight telescope constructed by the Commissariat a l'Energie Atomique (Saclay) and the Centre d'Etude Spatiale des Rayonnements (Toulouse) was used for gamma ray flux measurements. The atmospheric component was studied from balloon as a function of the pressure and the energy. Gamma ray fluxes were also measured with the telescope axis oriented in various directions and with the experiment inverted. The atmospheric and diffuse components were determined in various energy ranges.

Agrinier, B. (Centre d'Etudes Nucleaires de Saclay (France)); Lavigne, J.M. (Centre d'Etude Spatiale des Rayonnements, Toulouse (France)); Da Costa Ferreira Neri, J.A.

1992-02-01

223

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

NASA Astrophysics Data System (ADS)

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.

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

2012-10-01

224

Ionizing radiation-stimulated diffusion and desorption of hydrogen from metals  

NASA Astrophysics Data System (ADS)

The processes of hydrogen diffusion from a sample depth activated by electrons with an energy of tens of keV are studied. The difference from the known models of electron-stimulated desorption, which consider as a rule electron energies from 0.5 to several keV, is noted. The proposed model is shown to correspond to at least two established experimental facts: the nonlinear dependence of hydrogen isotope desorption on the electron beam current density affecting the sample and the dependence of hydrogen desorption on the irradiation time of the sample.

Tyurin, Yu. I.; Nikitenkov, N. N.; Larionov, V. V.

2011-06-01

225

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

SciTech Connect

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.

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

1989-01-01

226

Low Dose Radiation Research  

NSDL National Science Digital Library

The US Department of Energy's Low Dose Radiation Research Program supports research that investigates the health risks from exposure to radiation at low levels. This Web site provides an overview of radiation biology, up-to-date information and archived results from program-related research, and other resources for the benefit of researchers and the general public alike. Some research projects include comparing low dose radiation to endogenous oxidative damage, determining thresholds for radiation exposure, determining genetics factors that make some individuals more susceptible to radiation-induced damage, and more.

227

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

NASA Astrophysics Data System (ADS)

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.

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

2011-11-01

228

Measurements of the anisotropy of the cosmic background radiation and diffuse galactic emission at millimeter and submillimeter wavelengths  

SciTech Connect

The results of a balloon-borne observing program to measure the large angular scale brightness distribution of the 2.7 K cosmic background radiation (CBR) at millimeter and submillimeter wavelengths are reported. A new determination of the dipole anisotropy of the CBR is found with 3.40 + or - 0.42 mK toward alpha = 12.1 + or - 0.24 hr, delta = - 23 + or - 5 deg in a 1.2 to 8/cm band and 4.7 + or - 1.4 mK toward alpha = 9.9 + 1.7 or - 1.1 hr, delta = - 38 + or - 21 deg between 5 and 18/cm, where the amplitudes are listed as thermodynamic temperatures. New estimates of the absolute temperature in these two bands of 2.86 + or - 0.26 K and 3.01 + or - 0.31 are obtained under the assumption that the CBR has a Planck spectrum. The diffuse Galactic emission is fitted by a secant distribution in Galactic latitude, and the resulting Galactic pole antenna temperatures are given. Maps of sky brightness, measurements of zodiacal emission, and measurements of fluctuations of the atmospheric emission which dominates the noise budget are also presented. 40 references.

Halpern, M.; Benford, R.; Meyer, S.; Muehlner, D.; Weiss, R.

1988-09-01

229

RADIATION SAFETY CONSIDERATION DURING INTRAOPERATIVE RADIATION THERAPY.  

PubMed

Using in-house-designed phantoms, the authors evaluated radiation exposure rates in the vicinity of a newly acquired intraoperative radiation therapy (IORT) system: Axxent Electronic Brachytherapy System. The authors also investigated the perimeter radiation levels during three different clinical intraoperative treatments (breast, floor of the mouth and bilateral neck cancer patients). Radiation surveys during treatment delivery indicated that IORT using the surface applicator and IORT using balloons inserted into patient body give rise to exposure rates of 200 mR h(-1), 30 cm from a treated area. To reduce the exposure levels, movable lead shields should be used as they reduce the exposure rates by >95 %. The authors' measurements suggest that intraoperative treatment using the 50-kVp X-ray source can be administered in any regular operating room without the need for radiation shielding modification as long as the operators utilise lead aprons and/or stand behind lead shields. PMID:25267855

Mobit, Paul N; Rajaguru, Priyadarshini; Brewer, Michael; Baird, Michael; Packianathan, Satyaseelan; Yang, Claus Chunli

2014-09-28

230

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)

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.

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

2014-10-01

231

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

SciTech Connect

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.

Golshani, Negin, E-mail: negingolshani@gmail.com; Mohammadi, V.; Schellevis, H.; Beenakker, C. I. M.; Ishihara, R. [ECTM, DIMES, Faculty of Electrical Engineering (EWI), Delft University of Technology (TU Delft), Feldmannweg 17, P.O. Box 5053, 2628 CT Delft (Netherlands)

2014-10-01

232

Radiation Protection Handbook  

NASA Technical Reports Server (NTRS)

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.

1972-01-01

233

Understanding Radiation: Overview  

MedlinePLUS

... Radiation Radiation that has enough energy to move atoms in a molecule around or cause them to ... enough energy to remove tightly bound electrons from atoms, thus creating ions. Health Effects Health effects are ...

234

Radiation measuring instrumentation  

NASA Technical Reports Server (NTRS)

Four radiation measuring instruments were developed. These are: (1) improved detector probe, (2) neutron spectrometer--dosimeter, (3) portable ultraviolet spectro-radiometer; and (4) pocket ionization chamber radiation dosimeter. A brief description of each of these devices is presented.

Piltingsrud, H. V.

1975-01-01

235

Cell Radiation Experiment System  

NASA Technical Reports Server (NTRS)

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.

Morrison, Dennis R.

2010-01-01

236

External Radiation Therapy  

MedlinePLUS Videos and Cool Tools

Narrator: When the cancer is not completely contained in the prostate or when the patient is older the treatment that is frequently used is radiation therapy. Gunnar Zagars, M.D.: There are different forms of radiation for prostate ...

237

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? ...

238

Radiation Exposure and Pregnancy  

MedlinePLUS

... on the Health Physics Society "Ask the Experts" Web site. 3 Glossary Dose A general term used ... 2010. Radiation Answers, www.radiationanswers.org is a Web site that answers questions about radiation and was ...

239

Calculate Your Radiation Dose  

NSDL National Science Digital Library

This calculator by the Environmental Protection Agency allows you to estimate your annual radiation dose. The calculator is easy to use and the bottom of the page includes links to more information about radiation dosage.

2011-05-12

240

Prostate radiation - discharge  

MedlinePLUS

... these side effects: Skin problems during or after prostate radiation treatment is rare. Your skin over the ... keeping or getting an erection may occur after prostate radiation therapy but may not be noticed for ...

241

Radiation and Your Health  

MedlinePLUS

... air, airline travel, some medical procedures, computers, and nuclear weapons test fallout. Â Understanding Radiation Radiation, which exists ... Risk Assessment Project Fernald Dosimetry Reconstruction Project Hanford Nuclear Weapons Facility The Hanford Thyroid Disease Study HTDS Guide ...

242

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

243

Radiation effects in space  

SciTech Connect

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)

Fry, R.J.M.

1986-01-01

244

Chest radiation - discharge  

MedlinePLUS

... teaspoon of salt and one quarter teaspoon of baking soda in 8 ounces of warm water. Gargle with ... National Cancer Institute. Radiation therapy and you: support for people with cancer. http://www.cancer.gov/cancertopics/coping/radiation- ...

245

Near-Infrared Spectroscopy of Diffuse Galactic Radiation with AKARI/IRC  

NASA Astrophysics Data System (ADS)

We present the results of near-infrared (NIR: 2.5-5 µm) spectroscopy of diffuse Galactic sources on the Galactic plane obtained with the Infrared Camera (IRC) on board AKARI. The spectral region of 2.5-5 µm is rich in various emission and absorption features. In this report, we focus on the H2 O and CO2 ice absorption features at 3.0 and 4.3 µm, respectively, and report a search for features of deuterated polycyclic aromatic hydrocarbons (PAHs) in 4.4-4.6 µm. The column densities of CO2 and H2 O ices show a correlation in agreement with that obtained with ISO observations. The correlation nearly crosses the origin, suggesting that H2 O and CO2 ices form in tandem for a wide range of physical conditions. The ratio of the ice column densities in AFGL2591 along the slit is relatively constant over an area of 30?? , also supporting the tandem formation of H2 O and CO2 ices. The H2 O ice column density shows a weak trend with AV estimated from HI recombination lines, which is in contrast to the clear correlation seen toward quiescent clouds. The weak correlation may be attributed partly to the uncertainty in AV and/or a range of the environmental conditions in the present targets. Only weak excess emission is seen in 4.4-4.6 µm in the spectra of the Orion bar, M17, and a reflection nebula. From these spectra, the ratio of deuterated PAHs to undeuterated PAHs is estimated as 3% at most. This is significantly smaller than the previously reported value and suggests that missing deuterium must reside in large PAHs that do not emit the 3 µm bands, if it is depleted into PAHs.

Onaka, T.; Mori, T.; Sakon, I.; Ohsawa, R.; Nakamura, T.; Lee, H. G.; Koch, I. M.; Shimonishi, T.; Kaneda, H.; Okada, Y.; Tanaka, M.

246

Dangers of Radiation Exposure  

NSDL National Science Digital Library

This is a lesson about radiation and the various sources of radiation that a spacecraft may encounter in its journey. Learners will calculate their annual exposure to high-energy radiation, identify sources of high-energy radiation, and explain why the near-Mercury environment is a concern for the Mercury MESSENGER mission. This is lesson 2 of 4 in the high school track of a module, titled Staying Cool. Note: the student guide starts on p. 17 of the PDF.

247

JPL Radiation Effects Facilities  

NASA Technical Reports Server (NTRS)

Radiation Effects Group investigates the effects of space radiation on present and future microelectronic and optoelectronic technologies, evaluate the risk of using them in specific space missions, and recommend component and design techniques for JPL and NASA programs to reduce reliability risk from space radiation.

Thorbourn, Dennis

2013-01-01

248

Spacecraft radiator systems  

NASA Technical Reports Server (NTRS)

A spacecraft radiator system designed to provide structural support to the spacecraft. Structural support is provided by the geometric "crescent" form of the panels of the spacecraft radiator. This integration of radiator and structural support provides spacecraft with a semi-monocoque design.

Anderson, Grant A. (Inventor)

2012-01-01

249

Radiation and cellular response  

SciTech Connect

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.

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

1983-01-01

250

astroph/9507030 Gravitational Radiation  

E-print Network

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

Fygenson, Deborah Kuchnir

251

Radiation Damping with Inhomogeneous  

E-print Network

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

Augustine, Mathew P.

252

Ultraviolet radiation and immunosuppression.  

PubMed

Ultraviolet (UV) radiation is a complete carcinogen. The effects of UV radiation are mediated via direct damage to cellular DNA in the skin and suppression of image surveillance mechanisms. In the context of organ transplantation, addiction of drugs which suppress the immune system add greatly to the carcinogenicity of UV radiation. This review considers the mechanisms of such effects. PMID:19775363

Murphy, G M

2009-11-01

253

Infrasound Radiation of Cyclone  

Microsoft Academic Search

Tropical cyclones produce strong perturbations of atmosphere and the ocean surface accompanying by an acoustical radiation. Infrasonic signals in the 0.1–0.5 frequency band can be observed at a distances of thousands of miles from the cyclone. There are specific features of the mechanism of infrasound radiation by cyclone. The radiated sound can be trapped by atmospheric wave guide. The presence

K. Naugolnykh; S. Rybak

2006-01-01

254

Ionizing Radiation: The issue of radiation quality  

NASA Astrophysics Data System (ADS)

Types of Ionising radiations are differentiated from each other by fundamental characteristics of their energy deposition patterns when they interact with biological materials. At the level of the DNA these non-random patterns drive differences in the yields and distributions of DNA damage patterns and specifically the production of clustered damage or complex lesions. The complex radiation fields found in space bring significant challenges for developing a mechanistic understanding of radiation effects from the perspective of radiation quality as these consist of a diverse range of particle and energy types unique to the space environment. Linear energy transfer, energy deposited per unit track length in units of keV per micron, has long been used as a comparator for different types of radiation but has limitations in that it is an average value. Difference in primary core ionizations relative to secondary delta ray ranges vary significantly with particle mass and energy leading to complex interrelationships with damage production at the cellular level. At the cellular level a greater mechanistic understanding is necessary, linking energy deposition patterns to DNA damage patterns and cellular response, to build appropriate biophysical models that are predictive for different radiation qualities and mixed field exposures. Defined studies using monoenergetic beams delivered under controlled conditions are building quantitative data sets of both initial and long term changes in cells as a basis for a great mechanistic understanding of radiation quality effects of relevance to not only space exposures but clinical application of ion-beams.

Prise, Kevin; Schettino, Giuseppe

255

Appendix F. Radiation Appendix F. Radiation F-3  

E-print Network

Appendix F. Radiation #12;#12;Appendix F. Radiation F-3 Appendix F. Radiation This appendix presents basic facts about radiation. The information is intended to be a basis for un- derstanding), not as a comprehensive discussion of radiation and its effects on the environment and biological systems. Radiation comes

Pennycook, Steve

256

Radiation Injury to the Brain  

MedlinePLUS

RADIATION INJURY TO THE BRAIN Radiation treatments affect all cells that are targeted. This means where normal ... accurate treatment is still with one session radiosurgery. RADIATION THERAPY: Whole brain radiation therapy (WBRT) may target ...

257

Radiation Shielding and Radiological Protection  

E-print Network

Radiation Shielding and Radiological Protection J. Kenneth Shultis Richard E. Faw Department@triad.rr.com Radiation Fields and Sources ................................................ . Radiation Field Variables........................................................... .. Direction and Solid Angle Conventions ......................................... .. Radiation Fluence

Shultis, J. Kenneth

258

Radiation Safety Program Annual Review  

E-print Network

1 Radiation Safety Program Annual Review Calendar Year 2010 Prepared by: Karen Janiga, MS Radiation.................................................................................................3 MANAGEMENT OVERSIGHT OF THE RADIATION SAFETY/LASER SAFETY PROGRAMS .............3 LICENSE RENEWAL /AMENDMENTS/UPDATES .........................................................................4 RADIATION

Lyubomirsky, Ilya

259

Radiation: Facts, Risks and Realities  

MedlinePLUS

... to natural radiation comes from other elements in Earth’s crust, such as thorium and potassium. The radiation ... area. Another natural source is cosmic (space) radiation. Earth is constantly exposed to radiation created by processes ...

260

Radiation signal processing system  

SciTech Connect

An improved signal processing system for radiation imaging apparatus comprises: a radiation transducer producing transducer signals proportional to apparent spatial coordinates of detected radiation events; means for storing true spatial coordinates corresponding to a plurality of predetermined apparent spatial coordinates relative to selected detected radiation events said means for storing responsive to said transducer signal and producing an output signal representative of said true spatial coordinates; and means for interpolating the true spatial coordinates of the detected radiation events located intermediate the stored true spatial coordinates, said means for interpolating communicating with said means for storing.

Bennett, M.; Knoll, G.; Strange, D.

1980-07-08

261

Radiation protection in space  

SciTech Connect

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.

Blakely, E.A. [Lawrence Berkeley Lab., CA (United States); Fry, R.J.M. [Oak Ridge National Lab., TN (United States)

1995-02-01

262

Mossbauer spectrometer radiation detector  

NASA Technical Reports Server (NTRS)

A Mossbauer spectrometer with high efficiencies in both transmission and backscattering techniques is described. The device contains a sodium iodide crystal for detecting radiation caused by the Mossbauer effect, and two photomultipliers to collect the radiation detected by the crystal. When used in the transmission technique, the sample or scatterer is placed between the incident radiation source and the detector. When used in a backscattering technique, the detector is placed between the incident radiation source and the sample of scatterer such that the incident radiation will pass through a hole in the crystal and strike the sample. Diagrams of the instrument are provided.

Singh, J. J. (inventor)

1973-01-01

263

Solar cell radiation handbook  

NASA Technical Reports Server (NTRS)

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.

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

1973-01-01

264

Nuclear Energy: Radiation Exposure  

NSDL National Science Digital Library

This lesson provides an overview of the sources and potential effects of radiation exposure. Topics include the history of the United States' domestic nuclear power program, the concept of ionizing radiation, and how radiation dosage is measured. There is also discussion of what constitutes a lethal dose of radiation and potential sources of exposure. The lesson includes an activity in which students measure their individual yearly exposures to radiation by making an inventory of lifestyle factors that affect their potential dosage and using an online calculator to sum up the contributions from the various sources.

Pratte, John

265

Radiation protection and instrumentation  

NASA Technical Reports Server (NTRS)

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.

Bailey, J. V.

1975-01-01

266

Radiation-induced gliomas  

PubMed Central

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

Prasad, Gautam; Haas-Kogan, Daphne A.

2013-01-01

267

Synchrotron radiation from protons  

SciTech Connect

Synchrotron radiation from protons, though described by the same equations as the radiation from electrons, exhibits a number of interesting features on account of the parameters reached in praxis. In this presentation, we shall point out some of the features relating to (i) normal synchrotron radiation from dipoles in proton machines such as the High Energy Booster and the Superconducting Super Collider; (ii) synchrotron radiation from short dipoles, and its application to light monitors for proton machines, and (iii) synchrotron radiation from undulators in the limit when, the deflection parameter is much smaller than unity. The material for this presentation is taken largely from the work of Hofmann, Coisson, Bossart, and their collaborators, and from a paper by Kim. We shall emphasize the qualitative aspects of synchrotron radiation in the cases mentioned above, making, when possible, simple arguments for estimating the spectral and angular properties of the radiation. Detailed analyses can be found in the literature.

Dutt, S.K.

1992-12-01

268

High-power radiating plasma  

NASA Technical Reports Server (NTRS)

The physical principles underlying the use of radiating plasmas for the optical pumping of lasers are described. Particular consideration is given to the properties of radiating plasmas; radiation selectivity; the dynamics, equilibrium, and stability of radiating plasmas; the radiative Reynolds number; and experimental results on radiating discharges.

Rozanov, V. B.; Rukhadze, A. A.

1984-01-01

269

Simple Waves in Ideal Radiation Hydrodynamics  

SciTech Connect

In the dynamic diffusion limit of radiation hydrodynamics, advection dominates diffusion; the latter primarily affects small scales and has negligible impact on the large scale flow. The radiation can thus be accurately regarded as an ideal fluid, i.e., radiative diffusion can be neglected along with other forms of dissipation. This viewpoint is applied here to an analysis of simple waves in an ideal radiating fluid. It is shown that much of the hydrodynamic analysis carries over by simply replacing the material sound speed, pressure and index with the values appropriate for a radiating fluid. A complete analysis is performed for a centered rarefaction wave, and expressions are provided for the Riemann invariants and characteristic curves of the one-dimensional system of equations. The analytical solution is checked for consistency against a finite difference numerical integration, and the validity of neglecting the diffusion operator is demonstrated. An interesting physical result is that for a material component with a large number of internal degrees of freedom and an internal energy greater than that of the radiation, the sound speed increases as the fluid is rarefied. These solutions are an excellent test for radiation hydrodynamic codes operating in the dynamic diffusion regime. The general approach may be useful in the development of Godunov numerical schemes for radiation hydrodynamics.

Johnson, B M

2008-09-03

270

Simple Waves in Ideal Radiation Hydrodynamics  

E-print Network

In the dynamic diffusion limit of radiation hydrodynamics, advection dominates diffusion; the latter primarily affects small scales and has negligible impact on the large scale flow. The radiation can thus be accurately regarded as an ideal fluid, i.e., radiative diffusion can be neglected along with other forms of dissipation. This viewpoint is applied here to an analysis of simple waves in an ideal radiating fluid. It is shown that much of the hydrodynamic analysis carries over by simply replacing the material sound speed, pressure and index with the values appropriate for a radiating fluid. A complete analysis is performed for a centered rarefaction wave, and expressions are provided for the Riemann invariants and characteristic curves of the one-dimensional system of equations. The analytical solution is checked for consistency against a finite difference numerical integration, and the validity of neglecting the diffusion operator is demonstrated. An interesting physical result is that for a material component with a large number of internal degrees of freedom and an internal energy greater than that of the radiation, the sound speed increases as the fluid is rarefied. These solutions are an excellent test for radiation hydrodynamic codes operating in the dynamic diffusion regime. The general approach may be useful in the development of Godunov numerical schemes for radiation hydrodynamics.

Bryan M. Johnson

2008-11-24

271

Radiation physics, biophysics, and radiation biology  

SciTech Connect

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.

Hall, E.J.; Zaider, M.

1993-05-01

272

Radiation exposure and pregnancy.  

PubMed

Radiological exposure from nuclear power reactor accidents, transportation of nuclear waste accidents, industrial accidents, or terrorist activity may be a remote possibility, but it could happen. Nurses must be prepared to evaluate and treat pregnant women and infants who have been exposed to radiation, and to have an understanding of the health consequences of a nuclear or radiological incident. Pregnant women and infants are a special group of patients who need consideration when exposed to radiation. Initial care requires thorough assessment and decisions regarding immediate care needs. Ongoing care is based on type and extent of radiation exposure. With accurate, comprehensive information and education, nurses will be better prepared to help mitigate the effects of radiation exposure to pregnant women and infants following a radiological incident. Information about radiation, health effects of prenatal radiation exposure, assessment, patient care, and treatment of pregnant women and infants are presented. PMID:25333800

Labant, Amy; Silva, Christina

2014-01-01

273

Earth Radiation Measurement Science  

NASA Technical Reports Server (NTRS)

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.

Smith, G. Louis

2000-01-01

274

Jet Radiation Radius  

E-print Network

Jet radiation patterns are indispensable for the purpose of discriminating partons' with different quantum numbers. However, they are also vulnerable to various contaminations from the underlying event, pileup, and radiation of adjacent jets. In order to maximize the discrimination power, it is essential to optimize the jet radius used when analyzing the radiation patterns. We introduce the concept of jet radiation radius which quantifies how the jet radiation is distributed around the jet axes. We study the color and momentum dependence of the jet radiation radius, and discuss two applications: quark-gluon discrimination and $W$ jet tagging. In both cases, smaller (sub)jet radii are preferred for jets with higher PTs, albeit due to different mechanisms: the running of the QCD coupling constant and the boost to a color singlet system. A shrinking cone W jet tagging algorithm is proposed to achieve better discrimination than previous methods.

Zhenyu Han

2014-02-06

275

US EPA Radiation Protection  

NSDL National Science Digital Library

This website is from the US Environmental Protection Agency on Radiation Protection. It gives an overview of the basics including: Exposure to Gamma Radiation, Health Effects, and Protecting People from Gamma Radiation A gamma ray is a packet of electromagnetic energy--a photon. Gamma photons are the most energetic photons in the electromagnetic spectrum. Gamma rays (gamma photons) are emitted from the nucleus of some unstable (radioactive) atoms.

2010-04-05

276

Infrasound radiation of cyclones  

Microsoft Academic Search

Tropical cyclones produce strong perturbations of atmosphere and the ocean surface accompanied by acoustical radiation. Infrasonic signals in the 0.1-0.5 frequency band can be observed at distances of thousands of miles from the cyclone. The effect of infrasound radiation is connected apparently to the interaction of the counter-propagating sea-surface waves that produces a sound radiation of the doubled frequency of

Konstantin A. Naugolnykh

2005-01-01

277

RHOBOT: Radiation hardened robotics  

SciTech Connect

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.

Bennett, P.C.; Posey, L.D. [Sandia National Labs., Albuquerque, NM (United States)

1997-10-01

278

Potential theory of radiation  

NASA Technical Reports Server (NTRS)

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.

Chiu, Huei-Huang

1989-01-01

279

Radiation coloration resistant glass  

DOEpatents

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.

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

1986-01-01

280

Radiation coloration resistant glass  

DOEpatents

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.

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

1986-11-04

281

Management of radiation proctitis.  

PubMed

Radiation damage to the rectum following radiotherapy for pelvic malignancies can range from acute dose-limiting side effects to major morbidity affecting health-related quality of life. No standard guidelines exist for diagnosis and management of radiation proctitis. This article reviews the definitions, staging, and clinical features of radiation proctitis, and summarizes the modalities available for the treatment of acute and chronic radiation proctitis. Because of the paucity of well-controlled, blinded, randomized studies, it is not possible to fully assess the comparative efficacy of the different approaches to management. However, the evidence and rationale for use of the different strategies are presented. PMID:24280407

Sarin, Ankit; Safar, Bashar

2013-12-01

282

Synchrotron microbeam radiation therapy.  

E-print Network

??This thesis presents interdisciplinary, collaborative research in the field of synchrotron microbeam radiation therapy (MRT). Synchrotron MRT is an experimental radiotherapy technique under consideration for… (more)

Crosbie, Jeffrey

2008-01-01

283

An Introduction to Radiation General Definition of Radiation  

E-print Network

Module 1 An Introduction to Radiation #12;General Definition of Radiation · Ionizing radiation, for example, X-rays, gamma-rays, particles · Ionizing radiation is capable of removing an electron from the atom with which it interacts (ionization). · Non-ionizing radiation, for example, visible light

Massey, Thomas N.

284

High-energy proton radiation belt  

Microsoft Academic Search

The experiments and theories to explain the high-energy protons trapped ; in the Earth's radiation belt are reviewed. The theory of cosmic-ray albedo ; neutron decay injection of protons into the radiation belt is discussed. Radial ; diffusion and change in the Earth's dipole moment are included along with losses ; of protons by ionization and nuclear collision. It is

R. Stephen White

1973-01-01

285

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

SciTech Connect

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

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

2014-03-01

286

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)

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.

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

287

Radiation therapy simulation workbook  

SciTech Connect

This book presents format simulation procedures for all major areas. For each site it discusses clinical setting, technique, procedure and dosimetry, and provides measurement worksheets and set-up diagram sheets. Of interest to radiation oncologists, radiation therapy technologists, residents, and students.

Mizer, S.; Scheller, R.R.; Deye, J.A.

1986-01-01

288

Forecasting Radiation Fog  

NSDL National Science Digital Library

This is the second module in the Mesoscale Meteorology Primer series. This module starts with a forecast scenario that occurs during a winter radiation fog event in the Central Valley of California. After that, a conceptual section covers the physical processes of radiation fog through its life cycle. Operational sections addressing fog detection and forecasting conclude the module

COMET

2002-02-04

289

On Blackbody Radiation.  

ERIC Educational Resources Information Center

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)

Jain, Pushpendra K.

1991-01-01

290

Microcircuit radiation effects databank  

NASA Technical Reports Server (NTRS)

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.

1983-01-01

291

Radiation levels during operation  

Microsoft Academic Search

For full-power operation, the four major sources of radiation are: neutrons and gamma rays penetrating the sides of the shield tank; nitrogen-16 activity in the primary coolant; radiation leakage up and down the space between the reactor vessel and shield tank and scattering to accessible areas; and gamma rays from inelastic scattering of fast neutrons in the core. These four

Maringas

1978-01-01

292

RADIATION-CURABLE COATINGS  

EPA Science Inventory

The report gives results of an evaluation of radiation-curable coatings as a technology for reducing volatile organic compound (VOC) emissions from surface coating operations. urvey of the literature was conducted to assess the state of the technology and emissions from radiation...

293

Treatment of Radiation Injury  

PubMed Central

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

Akita, Sadanori

2014-01-01

294

Radiation effects in space  

SciTech Connect

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.

Fry, R.J.M.

1987-07-01

295

Enhanced-Radiation Weapons  

Microsoft Academic Search

The enhanced-radiation warhead is a particularly dangerous weapon insofar as it might mislead anyone into believing that its deployment would make it possible for nuclear warfare to be safely limited and tightly controlled; in this sense its very deployment could lower the threshold separating conventional warfare from nuclear warfare. Enhanced-radiation weapons are no more (and perhaps they are less) ''humane''

Fred M. Kaplan

1978-01-01

296

Radiation in the universe  

NASA Technical Reports Server (NTRS)

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.

Stuhlinger, Ernst; Truemper, Joachim; Weisskopf, Martin

1992-01-01

297

REVIEW OF RADIATION PNEUMONITIS  

Microsoft Academic Search

Radiation pneumonitis is a condition that develops in some patients ; following radiotherapy of tumors located in the chest and neck regions. This ; complication usually develops within 6 months after irradiation and may subside, ; or develop into progressive fibrosis. The clinical features of radiation ; pneumonitis are reviewed, the radiographic patterns are defined, and the ; pathologic lesions

1963-01-01

298

Global radiation oncology waybill  

PubMed Central

Background/aim Radiation oncology covers many different fields of knowledge and skills. Indeed, this medical specialty links physics, biology, research, and formation as well as surgical and clinical procedures and even rehabilitation and aesthetics. The current socio-economic situation and professional competences affect the development and future or this specialty. The aim of this article was to analyze and highlight the underlying pillars and foundations of radiation oncology, indicating the steps implicated in the future developments or competences of each. Methods This study has collected data from the literature and includes highlights from discussions carried out during the XVII Congress of the Spanish Society of Radiation Oncology (SEOR) held in Vigo in June, 2013. Most of the aspects and domains of radiation oncology were analyzed, achieving recommendations for the many skills and knowledge related to physics, biology, research, and formation as well as surgical and clinical procedures and even supportive care and management. Results Considering the data from the literature and the discussions of the XVII SEOR Meeting, the “waybill” for the forthcoming years has been described in this article including all the aspects related to the needs of radiation oncology. Conclusions Professional competences affect the development and future of this specialty. All the types of radio-modulation are competences of radiation oncologists. On the other hand, the pillars of Radiation Oncology are based on experience and research in every area of Radiation Oncology. PMID:24416572

Muñoz-Garzón, Victor; Rovirosa, Ángeles; Ramos, Alfredo

2013-01-01

299

Radiation Exposure Compensation Program  

NSDL National Science Digital Library

This is the Justice Department's Radiation Exposure Compensation Program homepage. This site features information about the Radiation Exposure Compensation Act, including claimant categories, claim forms, and the Energy Employees Occupational Illness Compensation Program Act. This site also provides a table illustrating a summary of all claims received and compensation paid to date.

U.S. Department of Justice Radiation Exposure Compensation Program

300

Chitosan and radiation chemistry  

NASA Astrophysics Data System (ADS)

Chitosan as a raw material with special properties has drawn attention of scientists working in the field of radiation processing and natural polymer products development, and also of specialists working in the field of radiation protection and oncologists. Especially the applications concern reduced molecular weight chitosan which still retain its chemical structure; such form of the compound is fostering biological, physical and chemical reactivity of the product. Chitosan degrades into fragments under ?-ray or electron beam irradiation. Antibacterial properties of the product are applied in manufacturing hydrogel for wound dressing and additional healing properties can be achieved by incorporating in the hydrogel matrix chitosan bonded silver clusters. Another possible application of chitosan is in reducing radiation damage to the radiation workers or radiation cured patients. In the case of radioisotopes oral or respiratory chitosan-based materials can be applied as chelators. Applications of chitosan in oncology are also reported.

Chmielewski, Andrzej G.

2010-03-01

301

Broadband optical radiation detector  

NASA Technical Reports Server (NTRS)

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.

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

1981-01-01

302

Dangers of Radiation Exposure  

NSDL National Science Digital Library

In the first part of the lesson, students calculate their yearly exposure rate to harmful high-energy radiation and cumulative effects over time. They then use the information to evaluate the various sources of radiation that are of greatest concern for them. In the second part of the lesson, students learn that spacecraft and other objects in space must be concerned with the same kinds of radiation to which humans are exposed. The MESSENGER spacecraft will orbit Mercury and be subjected to much more intense solar radiation than it would near Earth. Students discuss the notion that even though some of the radiation is needed to study the properties of the planet, too much of it can be quite damaging.

American Association for the Advancement of Science (AAAS;)

2005-03-15

303

Radiation Effects In Space  

SciTech Connect

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.

Tripathi, Ram K. [NASA Langley Research Center, MS - 188 E, Hampton VA 23681 (United States)

2011-06-01

304

Radiation and health*  

PubMed Central

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

Lindell, B.

1987-01-01

305

Fundamentals of Radiation Dosimetry  

NASA Astrophysics Data System (ADS)

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.

Bos, Adrie J. J.

2011-05-01

306

Fundamentals of Radiation Dosimetry  

SciTech Connect

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.

Bos, Adrie J. J. [Delft University of Technology, Faculty of Applied Sciences, Mekelweg 15, 2629JB Delft (Netherlands)

2011-05-05

307

Nuclear radiation actuated valve  

DOEpatents

A nuclear radiation actuated valve for a nuclear reactor. The valve has a valve first part (such as a valve rod with piston) and a valve second part (such as a valve tube surrounding the valve rod, with the valve tube having side slots surrounding the piston). Both valve parts have known nuclear radiation swelling characteristics. The valve's first part is positioned to receive nuclear radiation from the nuclear reactor's fuel region. The valve's second part is positioned so that its nuclear radiation induced swelling is different from that of the valve's first part. The valve's second part also is positioned so that the valve's first and second parts create a valve orifice which changes in size due to the different nuclear radiation caused swelling of the valve's first part compared to the valve's second part. The valve may be used in a nuclear reactor's core coolant system.

Christiansen, David W. (Kennewick, WA); Schively, Dixon P. (Richland, WA)

1985-01-01

308

Gravitational diffraction radiation  

E-print Network

We show that if the visible universe is a membrane embedded in a higher-dimensional space, particles in uniform motion radiate gravitational waves because of spacetime lumpiness. This phenomenon is analogous to the electromagnetic diffraction radiation of a charge moving near to a metallic grating. In the gravitational case, the role of the metallic grating is played by the inhomogeneities of the extra-dimensional space, such as a hidden brane. We derive a general formula for gravitational diffraction radiation and apply it to a higher-dimensional scenario with flat compact extra dimensions. Gravitational diffraction radiation may carry away a significant portion of the particle's initial energy. This allows to set stringent limits on the scale of brane perturbations. Physical effects of gravitational diffraction radiation are briefly discussed.

Vitor Cardoso; Marco Cavaglia; Mario Pimenta

2006-09-13

309

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...

310

RADIATION SAFETY MANUAL POLICIES AND PROCEDURES  

E-print Network

RADIATION SAFETY MANUAL POLICIES AND PROCEDURES FOR RADIATION PROTECTION AT TEXAS TECH UNIVERSITY................................................................................................................I-1 B. Radiation Protection Program...............................................................................I-3 D. Radiation Safety Management

Zhang, Yuanlin

311

Radiation Therapy: Additional Treatment Options  

MedlinePLUS

... Prostate Skin Upper GI Latest Research 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 ...

312

Radiation for Students and Teachers  

MedlinePLUS

... Public Reporters Librarians Students/Teachers PROGRAMS TOPICS REFERENCES Radiation Information for Students and Teachers Students/Teachers Main ... RadTown USA Careers People and Discoveries History of Radiation Protection Understanding Radiation Related Links Student Teacher Publications ...

313

Radiation Safety (Revised March 2010)  

E-print Network

Radiation Safety Manual (Revised March 2010) Updated December 2012 Stanford University, Stanford California #12; #12; Radiation Safety Manual (Revised March 2010) Updated Environmental Health and Safety, Stanford University, Stanford California #12; CREDITS This Radiation Safety

Kay, Mark A.

314

Laboratory Optical Spectroscopy of Thiophenoxy Radical and Its Profile Simulation as a Diffuse Interstellar Band Based on Rotational Distribution by Radiation and Collisions  

E-print Network

The gas-phase optical absorption spectrum of a thiophenoxy radical (C6H5S), 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 a C2v 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. 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 C2v molecule is a possible candidate for DIB with a band width variation dependent o...

Araki, Mitsunori; Tsukiyama, Koichi

2014-01-01

315

Laboratory Optical Spectroscopy of the Thiophenoxy Radical and Its Profile Simulation as a Diffuse Interstellar Band Based on Rotational Distribution by Radiation and Collisions  

NASA Astrophysics Data System (ADS)

The gas-phase optical absorption spectrum of the thiophenoxy radical (C6H5S), 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 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 × 1013 cm–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 2v molecule is a possible candidate for DIB with a band width variation dependent on the line of sight.

Araki, Mitsunori; Niwayama, Kei; Tsukiyama, Koichi

2014-11-01

316

Modifying Radiation Damage  

PubMed Central

Radiation leaves a fairly characteristic footprint in biological materials, but this is rapidly all but obliterated by the canonical biological responses to the radiation damage. The innate immune recognition systems that sense “danger” through direct radiation damage and through associated collateral damage set in motion a chain of events that, in a tissue compromised by radiation, often unwittingly result in oscillating waves of molecular and cellular responses as tissues attempt to heal. Understanding “nature’s whispers” that inform on these processes will lead to novel forms of intervention targeted more precisely towards modifying them in an appropriate and timely fashion so as to improve the healing process and prevent or mitigate the development of acute and late effects of normal tissue radiation damage, whether it be accidental, as a result of a terrorist incident, or of therapeutic treatment of cancer. Here we attempt to discuss some of the non-free radical scavenging mechanisms that modify radiation responses and comment on where we see them within a conceptual framework of an evolving radiation-induced lesion. PMID:20583981

Kim, Kwanghee; McBride, William H.

2011-01-01

317

Depression and ionizing radiation.  

PubMed

The objective of this at issue paper is the analysis of published data in correlation with the results of own research on the potential role of ionizing radiation in the genesis of depressive disorders. Depression is one of the most significant and long-term effect of the atomic bombings, nuclear testing and radiation emergences. The participants of the accident at the Chornobyl nuclear power plant increased prevalence of depression (18.0% and 13.1% in controls) and suicide rates. Depression is mainly observed in the structure of an organic mental disorder against cerebrovascular disease. The clinical pattern is dominated by asthenoadynamic and asthenoapathetic depression. Depressive disorders in radiation emergencies are multifactorial, that is the result of exposure to the complex psychogenic and radiological accident's factors, impact of traditional risk factors, somatic and neurological diseases, genetic predisposition, predisposition, etc. At the same time, exposure to ionizing radiation is a factor in the genesis of depression. This impact can be direct (to the Central Nervous System), and indirectly through the somatic and neurological abnormalities (multiorgan dysfunction) as well as by a variety of pathogenic mechanisms of ionizing radiation on the brain that have been discovered recently. It is strongly necessary analytical clinical and epidemiological studies with verification of depression and evidence-based establishment of the role of radiation and non-radiation risk factors. PMID:25191725

Loganovsky, K N; Vasilenko, Z L

2013-01-01

318

Stimulated coherent transition radiation  

SciTech Connect

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.

Hung-chi Lihn

1996-03-01

319

Radiation Safety System  

SciTech Connect

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.

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

2012-04-04

320

Composition for radiation shielding  

DOEpatents

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.

Kronberg, James W. (Aiken, SC)

1994-01-01

321

Radiative Decay:. Nonperturbative Approaches  

NASA Astrophysics Data System (ADS)

In radiative decay the coupled system, electron bound by some external potential plus radiation field, relaxes to the ground state in the long time limit. Our central issue is to prove such a behaviour on the basis of the corresponding Schrödinger equation. We argue that the spin-boson Hamiltonian is a simple, but physically still acceptable test case. We relate radiative decay to scattering theory and prove the existence of wave operators. Other approaches are reviewed and compared. Some challenging open problems are listed.

Hübner, Matthias; Spohn, Herbert

322

Microcircuit radiation effects databank  

NASA Technical Reports Server (NTRS)

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).

1983-01-01

323

The Intense Radiation Gas  

E-print Network

We present a new dispersion relation for photons that are nonlinearly interacting with a radiation gas of arbitrary intensity due to photon-photon scattering. It is found that the photon phase velocity decreases with increasing radiation intensity, it and attains a minimum value in the limit of super-intense fields. By using Hamilton's ray equations, a self-consistent kinetic theory for interacting photons is formulated. The interaction between an electromagnetic pulse and the radiation gas is shown to produce pulse self-compression and nonlinear saturation. Implications of our new results are discussed.

M. Marklund; P. K. Shukla; B. Eliasson

2005-03-08

324

Liquid sheet radiator  

NASA Technical Reports Server (NTRS)

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.

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

1987-01-01

325

Liquid sheet radiator  

NASA Technical Reports Server (NTRS)

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.

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

1987-01-01

326

Properties of undulator radiation  

NASA Astrophysics Data System (ADS)

Properties of the radiation emitted by a plane sinusoidal undulator are calculated in the far field approximation. Software has been developed to calculate the spectral distribution and polarization of the radiated intensity I(E) at a point on (or integrated over) a cross sectional observation plane of the photon beam. Spatial distribution of monochromatic radiation and power density contours are also calculated. Spectral broadening caused by an electron beam of finite spatial distribution is considered. Dispersive properties of the photon beam, including the dependence on deflection parameter, are analyzed. It is shown that reasonably constant intensity distribution I(E) can be obtained by properly shaping the beam acceptance aperture.

Veal, B. W.

327

Comments on the dynamical effects of radiative viscosity  

NASA Astrophysics Data System (ADS)

Diffusion limit radiation stress intensity tensor term size and radiating fluid dynamical equation term size estimates are presented, with emphasis on radiative viscosity effects. A complete parallelism is demonstrated between radiation and material terms, and Castor's (1972) comoving frame radiation energy and momentum equations, augmented by Buchler's (1979, 1982) acceleration terms, are shown to provide a completely consistent treatment of all effects associated with both radiation viscosity and the equivalent inertia of radiation enthalpy and radiant energy flux. Questions arising in connection with radiative viscous dissipation are discussed, and it is noted that in certain physically reasonable situations, the radiative viscous dissipation function may be only O(v-squared/c-squared) relative to the dominant radiative term in the radiating fluid gas-energy equation.

Mihalas, D.

1983-03-01

328

Testing a model of IR radiative losses  

NASA Astrophysics Data System (ADS)

Thermopile pyranometers exhibit IR radiative losses that affect global and diffuse shortwave measurements made with first class thermopile based instruments. Pyrgeometers can be used to measure the sky temperature and are used to calculate the pyranometer's IR radiative losses. Few solar monitoring sites are equipped with pyrgeometers necessary to account for the IR radiative losses associated with the pyranometers. High quality data from the Solar Radiation Research Laboratory (SRRL) at the National Renewable Energy Laboratory are used to test and further develop a model for the IR radiative losses without the use of pyrgeometer data. The various methods for obtaining IR radiative loss values are compared and contrasted using the SRRL data. A simple scaling method is proposed and tested to adjust the non-pyrgeometer based correlation models to sites with different sky temperature characteristics.

Vignola, Frank; Long, Charles N.; Reda, Ibrahim

2009-08-01

329

Portal radiation monitor  

DOEpatents

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.

Kruse, L.W.

1982-03-23

330

Photochemistry Radiation and Photolysiss  

E-print Network

Photochemistry Radiation and Photolysiss Objectives · Review the electromagnetic spectrum · Review #12;The Electromagnetic Spectrum For more information on the electromagnetic spectrum, see this website. #12;Essentials of Electromagnetic Energy The "unit" of electromagnetic energy is the photon

Toohey, Darin W.

331

The Space Radiation Environment  

NASA Technical Reports Server (NTRS)

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.

Bourdarie, Sebastien; Xapsos, Michael A.

2008-01-01

332

Radiation-Induced Bioradicals  

NASA Astrophysics Data System (ADS)

This chapter represents the second part of a review in which the production and application of radiation-induced radicals in biological matter are discussed. In part one the general aspects of the four stages (physical, physicochemical, chemical and biological) of interaction of radiation with matter in general and biological matter in particular, were discussed. Here an overview is presented of modem technologies and theoretical methods available for studying these radiation effects. The relevance is highlighted of electron paramagnetic resonance spectroscopy and quantum chemical calculations with respect to obtaining structural information on bioradicals, and a survey is given of the research studies in this field. We also discuss some basic aspects of modem accelerator technologies which can be used for creating radicals and we conclude with an overview of applications of radiation processing in biology and related fields such as biomedical and environmental engineering, food technology, medicine and pharmacy.

Lahorte, Philippe; Mondelaers, Wim

333

Radiation risks in pregnancy  

SciTech Connect

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.

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

1982-08-01

334

Portal radiation monitor  

DOEpatents

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.

Kruse, Lyle W. (Albuquerque, NM)

1985-01-01

335

Ionizing radiation detector  

DOEpatents

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.

Thacker, Louis H. (Knoxville, TN)

1990-01-01

336

Gas particle radiator  

NASA Technical Reports Server (NTRS)

A gas particle radiator adapted to operate in a microgravity space environment having a transparent boundary which transmits energy in the infrared spectrum, and a gas particle mixture that yields high absorption and emittances are described.

Chubb, Donald L. (inventor)

1988-01-01

337

Amorphous silicon radiation detectors  

DOEpatents

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.

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

1992-01-01

338

EM Radiation Program  

NSDL National Science Digital Library

The EM Radiation program displays the electric field vectors (in the x-y plane) and magnetic field contours (for the field in the z direction) calculated from the Lienard-Wiechert potentials for a charged particle. The default scenario shows the resulting radiation from a charged particle in simple harmonic motion. Additional particle trajectories can be specified using the Display | Switch GUI menu item. EM Radiation is an Open Source Physics program written for the teaching of electromagnetism. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the em_radiation.jar file will run the program if Java is installed. Other electromagnetism programs are also available. They can be found by searching ComPADRE for Open Source Physics, OSP, or electromagnetism.

Christian, Wolfgang

2008-05-20

339

[Genetic effects of radiation].  

PubMed

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

Nakamura, Nori

2012-03-01

340

Radiation Emergencies and Preparedness  

NSDL National Science Digital Library

This site provides information to help people protect themselves during and after a radiation emergency. It also provides information for professionals involved in planning for and responding to this type of emergency.

2010-03-02

341

Radiation Dose Chart  

NSDL National Science Digital Library

This is an illustration of the ionizing radiation dose a person can absorb from various sources. It provides a visual comparison of doses ranging from 0.1 microsieverts (from eating a banana) to a fatal dose of 8 sieverts.

Munroe, Randall

342

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

343

RESEARCH SAFETY RADIATION SAFETY  

E-print Network

INTEGRATED WASTE MANAGEMENT LABORATORY SAFETY AUDITS & COMPLIANCE BIOSAFETY and ENVIRONMENTAL HEALTHRESEARCH SAFETY RADIATION SAFETY ENVIRONMENTAL PROGRAMS HAZARDOUS MATERIALS CONTROLLED SUBSTANCES EMERGENCY MANAGEMENT and MISSION CONTINUITY FIRE PREVENTION and LIFE SAFETY GENERAL SAFETY TRAINING

344

Radiation damping on cryoprobes  

NASA Astrophysics Data System (ADS)

Radiation damping on 600 and 800 MHz cryoprobes was investigated. The phase angle ? between a vector 90° phase shifted to the precessing magnetization and the rf field induced in the coil was found to depend markedly on whether an FID was being acquired or not. The magnitude of the radiation damping field was sufficiently strong to restore 95% of the equilibrium water magnetization of a 90% H 2O sample in a 5 mm sample tube within about 5 ms following a 165° pulse. This can be exploited in water flip-back versions of NOESY and TOCSY experiments of proteins, but care must be taken to limit the effect of the radiation damping field from the water on the H a protons. Long water-selective pulses can be applied only following corrections. We developed a program for correcting pulse shapes if ? is non-zero. The WATERGATE scheme is shown to be insensitive to imperfections introduced by radiation damping.

Shishmarev, Dmitry; Otting, Gottfried

2011-12-01

345

Radiation damping on cryoprobes.  

PubMed

Radiation damping on 600 and 800 MHz cryoprobes was investigated. The phase angle ? between a vector 90° phase shifted to the precessing magnetization and the rf field induced in the coil was found to depend markedly on whether an FID was being acquired or not. The magnitude of the radiation damping field was sufficiently strong to restore 95% of the equilibrium water magnetization of a 90% H2O sample in a 5 mm sample tube within about 5 ms following a 165° pulse. This can be exploited in water flip-back versions of NOESY and TOCSY experiments of proteins, but care must be taken to limit the effect of the radiation damping field from the water on the Ha protons. Long water-selective pulses can be applied only following corrections. We developed a program for correcting pulse shapes if ? is non-zero. The WATERGATE scheme is shown to be insensitive to imperfections introduced by radiation damping. PMID:21955524

Shishmarev, Dmitry; Otting, Gottfried

2011-12-01

346

Radiation-induced meningiomas.  

PubMed

High dose radiation-induced meningiomas are a rare, severe and late complication of craniospinal radiotherapy for brain tumors. Radiation-induced meningiomas are, according to the literature, several times more frequent than radiogenic gliomas and sarcomas. It is suggested that every new case of radiogenic meningioma has to be reported to elucidate this particular pathologic entity with its many grey areas. In addition to high dose radiation-induced meningiomas, intracranial meningiomas were observed in patients who underwent low-dose radiation for tinea capitis in childhood, applied en mass to immigrants coming to Israel from the North Africa and the Middle East during the 1950. Authors summarize the data on radiogenic meningiomas from the literature and, as the previous radiotherapy may confer a low, but life-long risk for meningioma occurrence, they suggest that surveillance MRI after high dose cerebrospinal radiotherapy should be extended to several (3-5) decades after radiotherapy. PMID:11949834

Boljesíkova, E; Chorvath, M

2001-01-01

347

Amorphous silicon radiation detectors  

DOEpatents

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.

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

1992-11-17

348

The NCI Radiation Research Program: Grant portfolio and radiation  

E-print Network

The NCI Radiation Research Program: Grant portfolio and radiation dosimetry as applied and R37s). Of those that utilize radiation: · 6 use tissue culture models only · 110 utilize animal radiation (excepting those with human subjects or physics grants) mention dosimetry in the proposals (4

349

Radiation Safety Training Basic Radiation Safety Training for  

E-print Network

Radiation Safety Training Basic Radiation Safety Training for X-ray Users for Physics 461 & 462 Modern Physics Laboratory Spring 2007 #12;#12;Radiation Safety Department, University of Tennessee Protocol Title: Basic Radiation Safety Training for X-ray Users Drafted By: Chris Millsaps, RSS Reviewers

Dai, Pengcheng

350

Radiation Safety Training Basic Radiation Safety Training for  

E-print Network

Radiation Safety Training Basic Radiation Safety Training for Sealed Source Users for Physics 461 & 462 Modern Physics Laboratory Spring 2007 #12;Radiation Safety Department, University of Tennessee Purpose: To provide basic radiation safety training to the users of sealed sources located

Dai, Pengcheng

351

Radiation Safety Manual Dec 2012 Page 1 RADIATION SAFETY  

E-print Network

Radiation Safety Manual ­ Dec 2012 Page 1 RADIATION SAFETY MANUAL For Columbia University NewYork-Presbyterian Hospital New York State Psychiatric Institute Barnard College December 2012 #12;Radiation Safety Manual ­ Dec 2012 Page 1 Table of Contents Introduction Chapter I: Radiation Safety Program A. Program

Grishok, Alla

352

ACS WFC CCD Radiation Test: The Radiation Environment  

E-print Network

to electrons and protons trapped in the Van Allen radiation belts. The accumulated exposure to trapped1 ACS WFC CCD Radiation Test: The Radiation Environment Michael R. Jones Space Telescope Science by ionizing radiation. This document summarizes the modeling and analysis that was performed to determine

Sirianni, Marco

353

Method of enhancing radiation response of radiation detection materials  

DOEpatents

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.

Miller, Steven D. (Richland, WA)

1997-01-01

354

Intraocular radiation blocking  

Microsoft Academic Search

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

P. T. Finger; T. K. Ho; D. M. Fastenberg; R. A. Hyman; E. M. Stroh; S. Packer; H. D. Perry

1990-01-01

355

Radiation environment mapping  

NASA Technical Reports Server (NTRS)

An experimental set up to map the cosmic radiation field inside the Spacelab vehicle to determine the potential biological hazards present is described. In addition to the integral linear energy transfer (LET) spectrum for protons and HZE particles, the parameters to be determined include the total radiation dose; fluence of neutrons, protons, and high charge and energy (HZE) particles. These results are to be derived from measurements made in passive dosimeters.

Benton, E. Y.

1981-01-01

356

Radiation Color Plot  

NSDL National Science Digital Library

Energy from the sun reaches the Earth and some is absorbed by the air, land, and water. Some of the energy is reflected back into space, meaning it does not heat the land, air, or water. In this lesson students will read a color plot of Earth's absorption of the sun's radiation. They will evaluate causes for difference in absorption rates at different points around the world and draw conclusions about factors effecting absorption of sun's radiation.

357

[Radiation protection in radiation oncology. Yesterday, today, and tomorrow].  

PubMed

Publications about radiation protection issues are not very frequent in the 100-year-old history of Strahlentherapie und Onkologie. While at the beginning of the last century the problems of radiation protection were determined by the technical development of radiation therapy, the importance of radiation protection measures and knowledge about radiation protection by the persons involved has clearly increased. A new challenge is treating patients according to radiation safety issues to avoid the risk of stochastic late effects, such as radiation-induced secondary tumors. PMID:22907582

Herrmann, Th; Müller, R

2012-11-01

358

Packet personal radiation monitor  

DOEpatents

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.

Phelps, James E. (Knoxville, TN)

1989-01-01

359

Fabric space radiators  

SciTech Connect

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.

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

1988-01-01

360

Numerical Radiative Transfer  

NASA Astrophysics Data System (ADS)

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.

Kalkofen, Wolfgang

2009-07-01

361

The Radiation Chemistry Data Center  

NSDL National Science Digital Library

The Radiation Chemistry Data Center is an information resource provided by the Notre Dame Radiation Laboratory that is "dedicated to the collection, evaluation, and dissemination of data characterizing the reactions of transient intermediates produced by radiation chemical and photochemical methods." The main page offers links to Compilations of Chemical Property Data, Kinetics Databases, a Bibliographic Database, and Recent Papers in Radiation Chemistry and Photochemistry.

Madden, K.P.

362

Radiation Sensitization in Cancer Therapy.  

ERIC Educational Resources Information Center

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,…

Greenstock, Clive L.

1981-01-01

363

RADIATION ONCOLOGY TARGET YOUR FUTURE  

E-print Network

that focus on the treatment of cancer patients with radiation therapy (also known as radiotherapy); namely in Radiation Oncology: www.acareerinradiationoncology.com.au 3 Radiation therapy as a cancer treatment treatments like surgery or chemotherapy (anti-cancer drugs). Using highly precise doses of radiation

Tobar, Michael

364

Radiation Pressure Against Perfect Reflectors  

Microsoft Academic Search

The concept of radiation pressure exerted against a reflecting surface by electromagnetic waves and by sound waves in gases is a familiar one. The absence of radiation pressure for sound waves in a ``linear medium'' is becoming well known. The equations are somewhat different for the radiation pressure for these two cases where the radiation pressure is not zero. The

J. Elmer Rhodes

1953-01-01

365

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.

366

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 ...

367

Radiation health research, 1986 - 1990  

NASA Technical Reports Server (NTRS)

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.

1991-01-01

368

Radiation in Particle Simulations  

SciTech Connect

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.

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

2010-11-19

369

Radiation delivery system and method  

DOEpatents

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.

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

2002-01-01

370

Status of LDEF radiation modeling  

NASA Technical Reports Server (NTRS)

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.

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

1995-01-01

371

Modeling IR Radiative Loss from Eppley PSP Pyranometers Frank Vignola  

E-print Network

Renewable Energy Laboratory ABSTRACT A method has been developed to estimate IR radiative losses using solar. THE DATA The data used in this study come from the solar radiation monitoring site in Eugene, Oregon, irradiance, IR, modeling, global, diffuse, PSP 1. INTRODUCTION Since the 1970s, solar radiation data has been

Oregon, University of

372

Silicon radiation detector fabricated in a standard IC process  

Microsoft Academic Search

The authors present a silicon radiation detector for nuclear radiation, fabricated in a standard IC process, in which the generated charge carriers are collected by means of diffusion. A model is derived and experiments with optical and nuclear radiation are presented. Ionizing particles can be detected with a reasonable internal efficiency (65%) and response time (<10 ?s), and the spatial

S. E. Wouters; T. Otaredian; E. M. Schooneveld

1991-01-01

373

Comparative analysis of radiative transfer approaches for calculation of plane transmittance and diffuse attenuation coefficient of plane-parallel light scattering layers.  

PubMed

We present an analysis of a number of different approximations for the plane transmittance Tp and diffuse attenuation coefficient Kd of a semi-infinite, unbounded, plane-parallel, and optically homogeneous layer. The maximally wide optical conditions (from the full absorption to the full scattering and from the fully forward to the fully backward scattering) were considered. The approximations were analyzed from the point of view of their physical limitations and closeness to the numerical solution of the radiative transfer equation for the plane transmittance. The main criterion for inclusion of the models for analysis was the possibility of practical use, i.e., approximations were well parameterized and included only easily measured or estimated parameters. A detailed analysis of errors for different Tp and Kd models showed that the two-stream radiative transfer Ben-David model yields the best results over all optical conditions and depths. However, the quasi-single-scattering and polynomial Gordon's approximations proved to be the best for the depths close to zero. PMID:24514134

Sokoletsky, Leonid G; Budak, Vladimir P; Shen, Fang; Kokhanovsky, Alexander A

2014-01-20

374

Effect of variations in viscosity and thermal diffusivity on MHD heat and mass transfer flow over a porous inclined radiate plane  

NASA Astrophysics Data System (ADS)

This article is focused on the effectiveness of variable viscosity and variable thermal diffusivity on steady MHD heat and mass transfer flow over a semi-infinite porous inclined plate in the presence of thermal radiation and thermophoresis. The governing fundamental equations are transferred into a system of nonlinear similar ordinary differential equations, which are solved numerically by using Chebyshev pseudospectral method. Favorable comparisons with previously published work are performed and the results are found to be in very good agreement. Numerical results for the dimensionless velocity, temperature and concentration profiles as well as for the skin-friction coefficient, wall heat transfer and particle deposition rate are obtained and displayed graphically for pertinent physical parameters to show interesting aspects of the solutions.

El-Sayed, M. F.; Elgazery, N. S.

2011-12-01

375

Diffusivity transients and radiative recombination in intermixed In0.5Ga0.5As/GaAs quantum structures  

NASA Astrophysics Data System (ADS)

The effects of thermally induced compositional disordering on the luminescence from two-dimensional and zero-dimensional In0.5Ga0.5As/GaAs structures are examined. Quantum-mechanical numerical calculations modeling changes in the quantum-well (QW) confining potential with interdiffusion have been used to obtain values for diffusivities. These show transient behavior. Activation energies for interdiffusion (3.5+/-0.3 eV) are found to be similar to values reported for low-indium-content InxGa1-xAs/GaAs QW's. In quantum-dot structures, larger blueshifts can be obtained than in QW's under similar conditions. Interdiffusion decreased activation energies for radiative recombination, reflecting changes in confining potentials, and affecting lifetime ratios in recombination processes. The latter were observed in all intermixed heterostructures regardless of dimensionality.

Leon, R.; Williams, D. R. M.; Krueger, J.; Weber, E. R.; Melloch, M. R.

1997-08-01

376

Radiation Shielding Materials  

NASA Technical Reports Server (NTRS)

NASA has relied on the materials to provide radiation shielding for astronauts since the first manned flights. Until very recently existing materials in the structure of manned spacecraft as well as the equipment and consumables onboard have been taken advantage of for radiation shielding. With the advent of the International Space Station and the prospect of extended missions to the Moon or Mars, it has been found that the materials, which were included in the spacecraft for other reasons, do not provide adequate shielding. For the first time materials are being added to manned missions solely to improve the radiation shielding. It is now recognized that dual use materials must be identified/developed. These materials must serve a purpose as part of the spacecraft or its cargo and at the same time be good shielding. This paper will review methods for evaluating the radiation shielding effectiveness of materials and describe the character of materials that have high radiation shielding effectiveness. Some candidate materials will also be discussed.

Adams, James H., Jr.; Rose, M. Franklin (Technical Monitor)

2001-01-01

377

Remote radiation dosimetry  

DOEpatents

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.

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

1991-01-01

378

Remote radiation dosimetry  

DOEpatents

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.

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

1991-03-12

379

Reducing Radiation Damage  

SciTech Connect

This talk describes the use of a modified treatment sequence, i.e., radiation dose, geometry, dwell time, etc., to mitigate some of the deleterious effects of cancer radiotherapy by utilizing natural cell repair processes. If bad side effects can be reduced, a more aggressive therapy can be put into place. Cells contain many mechanisms that repair damage of various types. If the damage can not be repaired, cells will undergo apoptosis (cell death). Data will be reviewed that support the fact that a small dose of radiation will activate damage repair genes within a cell. Once the mechanisms are fully active, they will efficiently repair the severe damage from a much larger radiation dose. The data ranges from experiments on specific cell cultures using microarray (gene chip) techniques to experiments on complete organisms. The suggested effect and treatment is consistent with the assumption that all radiation is harmful, no matter how small the dose. Nevertheless, the harm can be reduced. These mechanisms need to be further studied and characterized. In particular, their time dependence needs to be understood before the proposed treatment can be optimized. Under certain situations it is also possible that the deleterious effects of chemotherapy can be mitigated and the damage to radiation workers can be reduced.

Blankenbecler, Richard

2006-06-05

380

Packet personal radiation monitor  

DOEpatents

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.

Phelps, J.E.

1988-03-31

381

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

PubMed

An in vivo exposure to 197??W/cm 2 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/cm 2 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. PMID:25321397

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

2014-10-01

382

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

NASA Astrophysics Data System (ADS)

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.

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

2014-10-01

383

Solar radiation on Mars: Stationary photovoltaic array  

NASA Technical Reports Server (NTRS)

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.

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

1993-01-01

384

Combined radiation and conduction heat transfer in high temperature fiber thermal insulation  

Microsoft Academic Search

Three different approaches for describing combined radiation and conduction heat transfer in fiber thermal insulation at high temperatures are analyzed and compared. The considered approaches include the radiation transfer equation or its approximations, approximation of radiation thermal conductivity and the radiation diffusion approximation for radiation transfer. The first causes difficulties due to the need for experimental measurement of optical properties,

Vadim A. Petrov

1997-01-01

385

Solar cell radiation handbook  

NASA Technical Reports Server (NTRS)

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.

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

1982-01-01

386

LDEF Satellite Radiation Analyses  

NASA Technical Reports Server (NTRS)

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.

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

1996-01-01

387

Radiation oncology (Vol. 2)  

SciTech Connect

This volume of the Radiation Oncology series features update reports on the current status of primary therapy for lung cancer and the role of radiation therapy in the treatment of hepatomas. Other articles describe the use of stereotaxic interstitial implantation in the treatment of malignant brain tumors and discuss the indications for and results of radiation as the primary or adjuvant treatment of large bowel cancer. Reports on new technological developments examine the biological basis and clinical potential of local-regional hyperthermia and photodynamic therapy. Included are reviews of the role of magnetic resonance imaging in the diagnostic evaluation of cancer and of three-dimensional treatment planning for high energy external beam radiotherapy.

Phillips, T.L.; Wara, W.

1987-01-01

388

Aerothermodynamic radiation studies  

NASA Technical Reports Server (NTRS)

We have built and made operational a 6 in. electric arc driven shock tube which alloys us to study the non-equilibrium radiation and kinetics of low pressure (0.1 to 1 torr) gases processed by 6 to 12 km/s shock waves. The diagnostic system allows simultaneous monitoring of shock radiation temporal histories by a bank of up to six radiometers, and spectral histories with two optical multi-channel analyzers. A data set of eight shots was assembled, comprising shocks in N2 and air at pressures between 0.1 and 1 torr and velocities of 6 to 12 km/s. Spectrally resolved data was taken in both the non-equilibrium and equilibrium shock regions on all shots. The present data appear to be the first spectrally resolved shock radiation measurements in N2 performed at 12 km/s. The data base was partially analyzed with salient features identified.

Donohue, K.; Reinecke, W. G.; Rossi, D.; Marinelli, W. J.; Krech, R. H.; Caledonia, G. E.

1991-01-01

389

Precision synchrotron radiation detectors  

SciTech Connect

Precision detectors to measure synchrotron radiation beam positions have been designed and installed as part of beam energy spectrometers at the Stanford Linear Collider (SLC). The distance between pairs of synchrotron radiation beams is measured absolutely to better than 28 /mu/m on a pulse-to-pulse basis. This contributes less than 5 MeV to the error in the measurement of SLC beam energies (approximately 50 GeV). A system of high-resolution video cameras viewing precisely-aligned fiducial wire arrays overlaying phosphorescent screens has achieved this accuracy. Also, detectors of synchrotron radiation using the charge developed by the ejection of Compton-recoil electrons from an array of fine wires are being developed. 4 refs., 5 figs., 1 tab.

Levi, M.; Rouse, F.; Butler, J.; Jung, C.K.; Lateur, M.; Nash, J.; Tinsman, J.; Wormser, G.; Gomez, J.J.; Kent, J.

1989-03-01

390

Radiation exposure during ureteroscopy  

SciTech Connect

Use of fluoroscopy during ureteroscopy increases the risk of radiation exposure to the urologist and patient. Radiation entrance dosages were measured at skin level in 37 patients, and at the neck, trunk and finger of the urologist, and neck and trunk of the circulating nurse. Radiation exposure time was measured in 79 patients, and was related to the purpose of the procedure and the type of ureteroscope used, whether rigid or flexible. Exposure could be minimized by decreasing the fluoroscopy time. A portable C-arm fluoroscopy unit with electronic imaging and last image hold mode should be used to minimize exposure time. Lead aprons and thyroid shields should be used by the urologist and other personnel in the endoscopy room.

Bagley, D.H.; Cubler-Goodman, A. (Thomas Jefferson Univ., Philadelphia, PA (USA))

1990-12-01

391

Semiconductor radiation detector  

DOEpatents

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.

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

2010-03-30

392

Uses of synchrotron radiation  

SciTech Connect

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.

Gordon, B.M.

1982-01-01

393

SODA: Solar Radiation Database  

NSDL National Science Digital Library

The Solar Database, or SoDa, is described as an integration and exploitation of networked Solar radiation Databases for environment monitoring and as a project that aims to integrate European-wide solar radiation resources (i.e. databases, processing chains and educational resources) into one, thematically organized, Web site. The search tool allows users to search for data from a variety of sources including Long Term Time Series Data, Climatological Data, Simulation of Radiation Under Clear Skies Data, Solar Energy Systems Data, and much more. Once a particular set is located, the user can view a description of the source and contents of the data, as well as click on the provided links to access them.

394

Composition for radiation shielding  

DOEpatents

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.

Kronberg, J.W.

1994-08-02

395

Audible radiation monitor  

SciTech Connect

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.

Odell, D.M.C.

1992-12-31

396

Radiation Induced Oral Mucositis  

PubMed Central

Patients receiving radiotherapy or chemotherapy will receive some degree of oral mucositis The incidence of oral mucositis was especially high in patients: (i) With primary tumors in the oral cavity, oropharynx, or nasopharynx; (ii) who also received concomitant chemotherapy; (iii) who received a total dose over 5,000 cGy; and (iv) who were treated with altered fractionation radiation schedules. Radiation-induced oral mucositis affects the quality of life of the patients and the family concerned. The present day management of oral mucositis is mostly palliative and or supportive care. The newer guidelines are suggesting Palifermin, which is the first active mucositis drug as well as Amifostine, for radiation protection and cryotherapy. The current management should focus more on palliative measures, such as pain management, nutritional support, and maintenance, of good oral hygiene PMID:20668585

PS, Satheesh Kumar; Balan, Anita; Sankar, Arun; Bose, Tinky

2009-01-01

397

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

NASA Technical Reports Server (NTRS)

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.

1974-01-01

398

Diffusion-Weighted MRI as a Biomarker of Tumor Radiation Treatment Response Heterogeneity: A Comparative Study of Whole-Volume Histogram Analysis versus Voxel-Based Functional Diffusion Map Analysis1  

PubMed Central

RATIONALE: Treatment of glioblastoma (GBM) remains challenging due in part to its histologic intratumoral heterogeneity that contributes to its overall poor treatment response. Our goal was to evaluate a voxel-based biomarker, the functional diffusion map (fDM), as an imaging biomarker to detect heterogeneity of tumor response in a radiation dose escalation protocol using a genetically engineered murine GBM model. EXPERIMENTAL DESIGN: Twenty-four genetically engineered murine GBM models [Ink4a-Arf-/-/Ptenloxp/loxp/Ntv-a RCAS/PDGF(+)/Cre(+)] were randomized in four treatment groups (n = 6 per group) consisting of daily doses of 0, 1, 2, and 4 Gy delivered for 5 days. Contrast-enhanced T1-weighted and diffusion-weighted magnetic resonance imaging (MRI) scans were acquired for tumor delineation and quantification of apparent diffusion coefficient (ADC) maps, respectively. MRI experiments were performed daily for a week and every 2 days thereafter. For each animal, the area under the curve (AUC) of the percentage change of the ADC (AUCADC) and that of the increase in fDM values (AUCfDM+) were determined within the first 5 days following therapy initiation. RESULTS: Animal survival increased with increasing radiation dose. Treatment induced a dose-dependent increase in tumor ADC values. The strongest correlation between survival and ADC measurements was observed using the AUCfDM+ metric (R2 = 0.88). CONCLUSION: This study showed that the efficacy of a voxel-based imaging biomarker (fDM) was able to detect spatially varying changes in tumors, which were determined to be a more sensitive predictor of overall response versus whole-volume tumor measurements (AUCADC). Finally, fDM provided for visualization of treatment-associated spatial heterogeneity within the tumor. PMID:24151536

Lemasson, Benjamin; Galbán, Craig J; Boes, Jennifer L; Li, Yinghua; Zhu, Yuan; Heist, Kevin A; Johnson, Timothy D; Chenevert, Thomas L; Galbán, Stefanie; Rehemtulla, Alnawaz; Ross, Brian D

2013-01-01

399

Radiation Hazard Detector  

NASA Technical Reports Server (NTRS)

NASA technology has made commercially available a new, inexpensive, conveniently-carried device for protection, of people exposed to potentially dangerous levels of microwave radiation. Microwaves are radio emissions of extremely high frequency. They can be hazardous but the degree of hazard is not yet well understood. Generally, it is believed that low intensity radiation of short duration is not harmful but that exposure to high levels can induce deep internal burns, affecting the circulatory and nervous systems, and particularly the eyes. The Department of Labor's Occupational Safety and Health Administration (OSHA) has established an allowable safe threshold of exposure. However, people working near high intensity sources of microwave energy-for example, radar antennas and television transmitters-may be unknowingly exposed to radiation levels beyond the safe limit. This poses not only a personal safety problem but also a problem for employers in terms of productivity loss, workman's compensation claims and possible liability litigation. Earlier-developed monitoring devices which warn personnel of dangerous radiation levels have their shortcomings. They can be cumbersome and awkward to use while working. They also require continual visual monitoring to determine if a person is in a dangerous area of radiation, and they are relatively expensive, another deterrent to their widespread adoption. In response to the need for a cheaper and more effective warning system, Jet Propulsion Laboratory developed, under NASA auspices, a new, battery-powered Microwave Radiation Hazard Detector. To bring the product to the commercial market, California Institute Research Foundation, the patent holder, granted an exclusive license to Cicoil Corporation, Chatsworth, California, an electronic components manufacturer.

1978-01-01

400

Radiation in Particle Simulations  

SciTech Connect

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.

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

2009-06-15

401

Radiation Monitoring Equipment Dosimeter Experiment  

NASA Technical Reports Server (NTRS)

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.

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

1992-01-01

402

LDEF Satellite Radiation Analyses  

NASA Technical Reports Server (NTRS)

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.

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

1996-01-01

403

Space radiation dosimetry.  

PubMed

In this report dosimetric measurements are presented which were performed during the missions Spacelab 1, D 1, Biocosmos 8 and Biocosmos 9. Detector packages consisting of plastic nuclear track detectors, nuclear emulsions and thermoluminescence dosimeters were exposed at different locations inside and outside spacecrafts behind more or less well defined shielding thicknesses. These detector systems which supplement each other in their registration characteristic allow to record all biological relevant portions of the radiation field separately. Dose equivalents for the astronauts have been calculated from the measurements using the quality factors as defined in the old and the new recommendations of the International Commission on Radiation Protection (ICRP). PMID:11538447

Reitz, G

1994-11-01

404

Tunable terahertz radiation source  

DOEpatents

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.

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

2014-01-21

405

Radiation monitor for liquids  

DOEpatents

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.

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

1999-03-02

406

Radiation monitor for liquids  

DOEpatents

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.

Koster, James E. (Los Alamos, NM); Bolton, Richard D. (Los Alamos, NM)

1999-01-01

407

Solar cell radiation handbook  

NASA Technical Reports Server (NTRS)

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.

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

1977-01-01

408

Tailoring silicon radiative properties  

NASA Astrophysics Data System (ADS)

We study several schemes to enhance the emission of radiation of silicon surfaces in the infrared. First, we investigate the emission pattern of microscale lamellar gratings ruled on doped silicon which is substantially modified due to the excitation of surface plasmons. In addition to their remarkable spectral selectivity, those sources emit 50% more than a plane interface of bulk doped silicon. An interferential antireflection system similar to a Salisbury screen is also considered. This broadband emitter allows a significant enhancement of the total emitted power compared to the plane interface. These results may have broad applications in sensing and radiative cooling.

Laroche, M.; Marquier, F.; Carminati, R.; Greffet, J.-J.

2005-06-01

409

Radiation transport in dust in disk geometry  

NASA Technical Reports Server (NTRS)

The main objective of the research program is twofold: (1) to develop a computer code to solve the problem of scattering, absorption and emission of photons by dust grains in a dusty medium with 2 dimensional disk geometry, and (2) to study the various physical and geometrical effects of 2 dimensional radiation transport on the thermal structure and radiation field. These tasks were accomplished and are briefly summarized. The method for solving the radiation transport problem in disk geometry is a generalization of the quasi-diffusion method (QDM) previously developed by the author.

Chun, Ming Leung

1986-01-01

410

Initial studies of the directional reflectance changes in pressed and sintered PTFE diffusers following exposure to contamination and ionizing radiation  

NASA Astrophysics Data System (ADS)

Changes in the directional reflectance properties of pressed and sintered polytetrafluoroethylene (PTFE) diffusers induced by exposure to vacuum ultraviolet (VUV) irradiation before and after controlled contamination with Pennzane are presented in this paper. A set of 99% reflective, white, optical grade diffuse calibration standards were irradiated with a VUV source positioned at 60° to the diffuser normal. The bidirectional reflectance distribution functions before and after contamination and VUV irradiation were measured and compared at a number of scatter geometries and wavelengths in the UV, VIS and IR spectral ranges. The 8° directional hemispherical reflectance’s were also measured and compared from 200?nm to 2500?nm. Our results indicate a measureable impact of VUV irradiation on pressed and sintered PTFE diffusers as manifested by a directional dependent change in their reflectance. Such an effect needs to be considered in the on-orbit deployment of PTFE diffusers.

Georgiev, G. T.; Butler, J. J.; Thome, K. J.; Ramos-Izquierdo, L. A.; Ding, L.; Graziani, L. J.; Meadows, G. A.

2014-12-01

411

Unruh radiation and Interference effect  

E-print Network

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.

Satoshi Iso; Yasuhiro Yamamoto; Sen Zhang

2011-02-23

412

Appendix G. Radiation Appendix G. Radiation G-3  

E-print Network

, or radiant energy, is energy in the form of waves or particles moving through space. Visi- ble light, heat, they are actually absorbing the radiant energy emitted by the sun. Electromagnetic radiation is radiation

Pennycook, Steve

413

An Inexpensive Radiation Counter.  

ERIC Educational Resources Information Center

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)

Holton, Brian; Balla, Zsolt

1985-01-01

414

VDT Emissions Radiate Debate.  

ERIC Educational Resources Information Center

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)

Morgan, Bill

1990-01-01

415

Photovoltaic radiation detector element  

DOEpatents

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.

Agouridis, D.C.

1980-12-17

416

Radiation detector spectrum simulator  

DOEpatents

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.

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

1985-04-09

417

Advances in radiation grafting  

Microsoft Academic Search

Graft copolymerization is an attractive means for modifying base polymers because grafting frequently results in the superposition of properties relating to the backbone and pendent chains. Among the various methods for initiating the grafting reaction, ionizing radiation is the cleanest and most versatile method of grafting available. Ion-exchange membranes play an important role in modern technology, especially in separation and

El-Sayed A. Hegazy; H. A. AbdEl-Rehim; H. Kamal; K. A. Kandeel

2001-01-01

418

Isotropy of Cosmic Radiation  

Microsoft Academic Search

Cosmic radiation data obtained at the Mass. Inst. of Tech. Volcano ; Ranch station in 1960 to 1961 were compared with that taken in 1959 to 1960 at ; the same location. The 1960 to 1961 data were obtained after the area of the ; array was increased by a factor of four and therefore have 3 times the ;

J. Linsley; L. Scarsi; P. J. Eccles; B. B. Rossi

1962-01-01

419

Radiations from hot nuclei  

NASA Technical Reports Server (NTRS)

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.

Malik, F. Bary

1993-01-01

420

Photochemistry Radiation and Photolysis  

E-print Network

Photochemistry Radiation and Photolysis Objectives · Review the electromagnetic spectrum · Review covalent) #12;The Electromagnetic Spectrum For more information on the electromagnetic spectrum, see in the ultraviolet region of the spectrum. What is photolysis, exactly? Absorption of a photon by a molecule

Toohey, Darin W.

421

Radiation Protection Basics  

MedlinePLUS

... have been contaminated or used for disposal of radioactive material. We also account for the shielding provided by buildings for a person working or living at a site that has been cleaned up. Health Effects This page describes the effects of radiation exposure.

422

Radiation detector spectrum simulator  

DOEpatents

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.

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

1987-01-01

423

Thermodynamics of Radiation Modes  

ERIC Educational Resources Information Center

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…

Pina, Eduardo; de la Selva, Sara Maria Teresa

2010-01-01

424

Multilayer radiation shield  

Microsoft Academic Search

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

John Arthur Urbahn; Evangelos Trifon Laskaris

2009-01-01

425

Surface Radiation Budget  

NASA Technical Reports Server (NTRS)

The Surface Radiation Budget (SRB) data sets contain global 3-hourly, daily and monthly averages of surface longwave and shortwave radiative properties, cloud amount, and meteorological properties computed using models. The main input data for these models include cloud information, top-of-atmosphere radiances and profiles of atmospheric water vapor and temperature. Some of the input data include Earth Radiation Budget Energy (ERBE) top-of-atmosphere clear-sky albedo and International Satellite Cloud Climatology Project (ISCCP) radiances and cloud amount. SRB parameters derived for the renewable energy community are also available from the Surface meteorology and Solar Energy (SSE) data set. Other SRB data are available from Clouds and the Earth's Radiant Energy System (CERES) and Multi-angle Imaging SpectroRadiometer (MISR). [Mission Objectives] The objective of the SRB Project is to produce and archive a global data set of shortwave (SW) and longwave (LW) surface and top of the atmosphere parameters. The data generated in the SRB project may be used in conjunction with other data sets to facilitate the development of renewable energy resources and increase understanding of radiative properties within the meteorological community. [Temporal_Coverage: Start_Date=1983-07-01; Stop_Date=2005-06-30] [Spatial_Coverage: Southernmost_Latitude=-90; Northernmost_Latitude=90; Westernmost_Longitude=-180; Easternmost_Longitude=180].

Stackhouse, Paul W. (Principal Investigator)

426

Radiation Dose Estimates from  

E-print Network

Summary: Radiation Dose Estimates from Hanford Radioactive Material Releases to the Air and the Columbia River April 21,1994 TheTechnid Steering Panel of the Hanford - Environmental Dose Reconstruction than 40years, the U.S. Government made plutonium for nuclear weapons at the Hanford

427

IONIZING RADIATION OF EGGS  

Technology Transfer Automated Retrieval System (TEKTRAN)

Contamination of eggs and egg products by Salmonella is associated with a significant number of illnesses in the U.S. each year. Ionizing radiation can inactivate Salmonella on the egg surface, in the egg white, and in the yolk of shell eggs, and has been approved by the U.S. FDA at doses up to 3.0...

428

Foundations of radiation hydrodynamics  

Microsoft Academic Search

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

D. Mihalas; B. W. Mihalas

1984-01-01

429

Paradoxes of Thermal Radiation  

ERIC Educational Resources Information Center

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,…

Besson, U.

2009-01-01

430

Radiation Source Replacement Workshop  

SciTech Connect

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.

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

2010-12-01

431

Cambridge Cosmology: Relic Radiation  

NSDL National Science Digital Library

This section of Cambridge Cosmology discusses cosmic background radiation present in our Universe. Also covered are topics such as the present temperature of the Universe as taken by the COBE satellite, fluctuations seen at the 'edge' of the Universe, and possible causes of these fluctuations.

Shellard, Paul

432

Psoriasis and ultraviolet radiation  

SciTech Connect

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.

Farber, E.M.; Nall, L. (Psoriasis Research Institute, Palo Alto, CA (United States))

1993-09-01

433

Radiation belts of Jupiter  

Microsoft Academic Search

Pioneer 10 courted relativistic electrons throughout the magnetosphere ; of Jupiter, with the greatest fluxes being inside 20 Jupiter radii. The peak ; flux of electrons with energy greater than 50 MeV was 1.3 x 107 per square ; centimeter per second at the innermost penetration of the radiation belts. ; (auth);

R. W. Fillius; C. E. McIlwain

1974-01-01

434

Nuclear Radiation Damages Minds!  

ERIC Educational Resources Information Center

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…

Blai, Boris, Jr.

435

Continuum radiation at Uranus  

SciTech Connect

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.

Kurth, W.S.; Gurnett, D.A. (Univ. of Iowa, Iowa City (United States)); Desch, M.D. (NASA Goddard Space Flight Center, Greenbelt, MD (United States))

1990-02-01

436

Alkoxy radical radiation products  

SciTech Connect

Single crystals of ribitol and 6-methylpurine-riboside were x-irradiated at 4.2 /sup 0/K. Alkoxy radicals were identified in the radiation products. The g tensor and proton coupling tensors, were determined from ENDOR and ESR studies. (AIP)

Box, H.C.; Budzinski, E.E.

1982-06-01

437

Radiation and immunotherapy  

PubMed Central

Anticancer immunotherapy holds great promises, as long-term responses to interleukin-2 have been observed in metastatic melanoma and renal cell carcinoma patients. However, improving the relative low rates of such responses has constituted a great challenge. In our experience, high-dose radiation combined with interleukin-2 provided encouraging results that are worth exploring further. PMID:23264923

Seung, Steven K.; Curti, Brendan; Crittenden, Marka; Urba, Walter

2012-01-01

438

GEWEX Radiative Flux Assessment  

Atmospheric Science Data Center

... detail and accuracy to diagnose the causes of recent climate variations in terms of the energy and water exchanges among the main ... project will provide a forum for consistent analysis of long-term radiative flux products, primarily top-of-atmosphere (TOA) and ...

2013-06-27

439

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...

440

Justification in Radiation Protection  

Microsoft Academic Search

In recent years the concept of Justification has increasingly come to the fore of the minds of legislators, users of radioactive materials and radiation protection specialists alike. Perhaps the most well known manifestation of this was the lengthy debate, ending in judicial review, about the Justification for the operation of the Thermal Oxide Reprocessing Plant (Thorp) at Sellafield and, more

David Owen

1999-01-01

441

Local microwave background radiation  

E-print Network

An inquiry on a possible local origin for the Microwave Background Radiation is made. Thermal MBR photons are contained in a system called {\\it magnetic bottle} which is due to Earth magnetic field and solar wind particles, mostly electrons. Observational tests are anticipated.

Domingos Soares

2014-11-13

442

Shield against radiations  

SciTech Connect

This patent describes a shield against ionizing radiations that comprises at least one layer of an aggregate-containing cement-based conglomerate or an aggregate-containing cement-based mortar wherein the aggregate consists essentially of floated galena or mixtures thereof which at least one boron mineral.

Grifoni, S.

1988-02-23

443

Acute radiation risk models  

NASA Astrophysics Data System (ADS)

Biologically motivated mathematical models, which describe the dynamics of the major hematopoietic lineages (the thrombocytopoietic, lymphocytopoietic, granulocytopoietic, and erythropoietic systems) in acutely/chronically irradiated humans are developed. These models are implemented as systems of nonlinear differential equations, which variables and constant parameters have clear biological meaning. It is shown that the developed models are capable of reproducing clinical data on the dynamics of these systems in humans exposed to acute radiation in the result of incidents and accidents, as well as in humans exposed to low-level chronic radiation. Moreover, the averaged value of the "lethal" dose rates of chronic irradiation evaluated within models of these four major hematopoietic lineages coincides with the real minimal dose rate of lethal chronic irradiation. The demonstrated ability of the models of the human thrombocytopoietic, lymphocytopoietic, granulocytopoietic, and erythropoietic systems to predict the dynamical response of these systems to acute/chronic irradiation in wide ranges of doses and dose rates implies that these mathematical models form an universal tool for the investigation and prediction of the dynamics of the major human hematopoietic lineages for a vast pattern of irradiation scenarios. In particular, these models could be applied for the radiation risk assessment for health of astronauts exposed to space radiation during long-term space missions, such as voyages to Mars or Lunar colonies, as well as for health of people exposed to acute/chronic irradiation due to environmental radiological events.

Smirnova, Olga

444

Radiation litmus paper  

SciTech Connect

Colorimetric radiation measurement has certain advantages over other methods; these advantages include the ability to measure extremely high doses and fluxes that would saturate other instrumentation. Colorimetry offers the possibility of inexpensive real-time measurements without the need for bulky or heavy equipment. The author is investigating the use of colorimetric threshold radiation measurement for first responders to potential radiological incidents, where advanced radiation measurement equipment would be inappropriate in terms of its size, weight, and complexity of operations. The author developed several new autocatalytic reactions for use in colorimetric radiation measurement. An autocatalytic reaction is one in which the products of the reaction further catalyze the reaction to produce a reaction that proceeds at an exponential rate. The autocatalytic reactions that were developed are triggered by gamma, neutron, or beta radiation. The products of these reactions are visualized with the unaided eye or measured spectrometrically. He achieved visible color changes in response to doses as low as 1.7 x 10{sup {minus}4} Gy (17 mR) of {sup 137}Cs gamma irradiation. By varying the chemical reaction parameters, such as concentrations, reagents, and reaction inhibitors, he can control the threshold dose at which the color change becomes visible. For example, by adjusting the equivalent of the chain length of the autocatalytic reaction two otherwise identical materials possess thresholds of 4.4 x 10{sup {minus}3} Gy (440 mR) or 3.0 x 10{sup {minus}3} Gy (300 mR). Alternatively, by controlling the concentration of the reagents or the volume of the reaction medium, the threshold dose can be varied linearly from 1.2 x 10{sup {minus}3} Gy (120 mR) to 5.8 x 10{sup {minus}3}Gy (580 mR). In summary, he developed the first viable low-dose colorimetric method for measuring ionizing radiation. The reagents are easy to synthesize and handle, and the method provides visible changes. Further experiments to determine dose rate responses and calibration for beta and neutron radiation are underway.

Warner, B.P.

1999-07-01

445

Space radiation testing of radiation-resistant glasses and crystals  

Microsoft Academic Search

With the number of cerium doped radiation resistant glasses available to the designer of space optics rapidly decreasing, it is critical to identify and characterize all potential sources of radiation resistant glasses and crystals. Unfortunately much of the data on radiation testing of glasses is quite old and often not completed at very high dose rates as might be experienced

Tammy D. Henson; Geoffrey K. Torrington

2001-01-01

446

SSC environmental radiation shielding  

SciTech Connect

The environmental radiation shielding requirements of the SSC have been evaluated using currently available computational tools that incorporate the well known processes of energy loss and degradation of high energy particles into Monte Carlo computer codes. These tools permit determination of isodose contours in the matter surrounding a source point and therefore the specification of minimum thicknesses or extents of shielding in order to assure annual dose equivalents less than some specified design amount. For the general public the annual dose equivalent specified in the design is 10 millirem, small compared to the dose from naturally occurring radiation. The types of radiation fall into two classes for the purposes of shielding determinations-hadrons and muons. The sources of radiation at the SSC of concern for the surrounding environment are the interaction regions, the specially designed beam dumps into which the beams are dumped from time to time, and beam clean-up regions where stops remove the beam halo in order to reduce experimental backgrounds. A final, unlikely source of radiation considered is the accidental loss of the full beam at some point around the ring. Conservative choices of a luminosity of 10{sup 34} cm{sup {minus}2}s{sup {minus}1} and a beam current three times design have been made in calculating the required shielding and boundaries of the facility. In addition to determination of minimum distances for the annual dose equivalents, the question of possible radioactivity produced in nearby wells or in municipal water supplies is addressed. The designed shielding distances and beam dumps are such that the induced radioactivity in ground water is safely smaller than the levels permitted by EPA and international agencies.

Jackson, J.D. [ed.

1987-07-01

447

Drug Information Related to Radiation Emergencies  

MedlinePLUS

... Radiation Emergencies (Centers for Disease Control and Prevention) Radiation Emergencies Drug Information Related to Radiation Emergencies Potassium Iodide ("KI") Information . Potassium Iodide (KI) ...

448

Radiation damage during surface analysis  

NASA Astrophysics Data System (ADS)

During surface analysis of solids by means of secondary ion mass spectrometry (SIMS), ion scattering spectrometry (ISS), Auger electron spectroscopy (AES) and photoelectron spectroscopy (XPS or ESCA), excitation with ions, electrons and photons can result in radiation-induced damage. Artefacts of this kind are for example morphological changes due to sputtering, stoichiometric changes (reduction, formation of new compounds, selective accumulations), electron and ion-induced adsorption and desorption, charge-dependent diffusion and structural changes (crystallization, amorphisation). Detection of compounds when using ions for excitation (SIMS and ISS) or in sputtering of solids for recording depth profiles in conjunction with all surface analysis methods is particularly critical due to the high energy of the ions transmitted to the solid. In AES, problems arise because of the high electron current densities generally used. A number of characteristic examples are presented to demonstrate which critical radiation doses must not be exceeded in "static" or "low damage" surface analysis. Artefact-free analyses of the upper monolayers of solids are achievable with all surface analysis methods by choosing suitable measurement parameters. When recording ion bombardment depth profiles and in microanalysis with high lateral resolution with scanning Auger microscopy (SAM) and ion microscopy, radiation damage cannot be excluded.

Storp, S.

449

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

SciTech Connect

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.

Biswas, Tithi; Dhakal, Sughosh [Department of Radiation Oncology, University of Rochester Medical Center, Rochester, New York (United States); Chen Rui; Hyrien, Ollivier [Department of Biostatistics, University of Rochester Medical Center, Rochester, New York (United States); Bernstein, Steven; Friedberg, Jonathan W.; Fisher, Richard I.; Liesveld, Jane; Phillips, Gordon [Department of Medicine, Division of Medical Oncology, University of Rochester Medical Center, Rochester, New York (United States); Constine, Louis S., E-mail: louis_constine@urmc.rochester.ed [Department of Radiation Oncology, University of Rochester Medical Center, Rochester, New York (United States); Department of Pediatrics, University of Rochester Medical Center, Rochester, New York (United States)

2010-05-01

450

Conical electromagnetic radiation flux concentrator  

NASA Technical Reports Server (NTRS)

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.

Miller, E. R.

1972-01-01

451

Acceleration and Classical Electromagnetic Radiation  

E-print Network

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.

E. N. Glass

2008-01-09

452

RADIATION SAFETY OFFICE UNIVERSITYOF MARYLAND  

E-print Network

RADIATION SAFETY OFFICE UNIVERSITYOF MARYLAND RADIATION SAFETY MANUAL UNIVERSITY OF MARYLAND College Park, Maryland Revised May 2001 #12;TABLE OF CONTENTS FORWARD . . . . . . . . . . . . . . . . . . . . . . . . 11 2.3.4.2. University of Maryland Personnel Visiting Other Facilities . . . . . . . . . . . . . 11 2

Rubloff, Gary W.

453

Radiation Therapy for Lung Cancer  

MedlinePLUS

... visit: National Cancer Institute www.cancer.gov/clinicaltrials Radiation Therapy Answers www.rtanswers.org STRO AMERICAN SOCIETY ... astro.org for more information. AMERICAN SOCIETY FOR RADIATION ONCOLOGY 8280 Willow Oaks Corporate Drive, Suite 500, ...

454

Doses from Medical Radiation Sources  

MedlinePLUS

... settings of the machine used to produce the radiation, in nuclear medicine on the amount of activity administered and ... and magnitude of occupational and public exposures from nuclear medicine ... Radiation Protection and Measurements; NCRP Report 124; 1996. United ...

455

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 ...

456

Gamma radiation field intensity meter  

DOEpatents

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.

Thacker, L.H.

1995-10-17

457

Gamma radiation field intensity meter  

DOEpatents

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.

Thacker, L.H.

1994-08-16

458

Stromal Mediation of Radiation Carcinogenesis  

PubMed Central

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

2011-01-01

459

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

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 Robert D. Stewart, Ph.D.Robert D. Stewart, Ph

Stewart, Robert D.

460

Spectroscopy Interaction of electromagnetic radiation  

E-print Network

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

Gerwert, Klaus

461

Radiation reaction in various dimensions  

Microsoft Academic Search

We discuss the radiation reaction problem for an electric charge moving in flat space-time of arbitrary dimensions. It is shown that four is the unique dimension where a local differential equation exists accounting for the radiation reaction and admitting a consistent mass renormalization (the Lorentz-Dirac equation). In odd dimensions Huygens's principle does not hold, and, as a result, the radiation

Dmitri V. Gal'Tsov

2002-01-01

462

Material Effectiveness for Radiation Shielding  

NASA Technical Reports Server (NTRS)

Materials with a smaller mean atomic mass, such as lithium (Li) hydride and polyethylene, make the best radiation shields for astronauts. The materials have a higher density of nuclei and are better able to block incoming radiation. Also, they tend to produce fewer and less dangerous secondary particles after impact with incoming radiation.

2003-01-01

463

Prevention of pelvic radiation disease  

PubMed Central

Pelvic cancers are among the most frequently diagnosed cancers worldwide. Treatment of patients requires a multidisciplinary approach that frequently includes radiotherapy. Gastrointestinal (GI) radiation-induced toxicity is a major complication and the transient or long-term problems, ranging from mild to very severe, arising in non-cancerous tissues resulting from radiation treatment to a tumor of pelvic origin, are actually called as pelvic radiation disease. The incidence of pelvic radiation disease changes according to the radiation technique, the length of follow up, the assessment method, the type and stage of cancer and several other variables. Notably, even with the most recent radiation techniques, i.e., intensity-modulated radiotherapy, the incidence of radiation-induced GI side effects is overall reduced but still not negligible. In addition, radiation-induced GI side effects can develop even after several decades; therefore, the improvement of patient life expectancy will unavoidably increase the risk of developing radiation-induced complications. Once developed, the management of pelvic radiation disease may be challenging. Therefore, the prevention of radiation-induced toxicity represents a reasonable way to avoid a dramatic drop of the quality of life of these patients. In the current manuscript we provide an updated and practical review on the best available evidences in the field of the prevention of pelvic radiation disease. PMID:25664197

Fuccio, Lorenzo; Frazzoni, Leonardo; Guido, Alessandra

2015-01-01

464

Radiation Therapy Technology Professional Curriculum  

E-print Network

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

Berdichevsky, Victor

465

Prevention of pelvic radiation disease.  

PubMed

Pelvic cancers are among the most frequently diagnosed cancers worldwide. Treatment of patients requires a multidisciplinary approach that frequently includes radiotherapy. Gastrointestinal (GI) radiation-induced toxicity is a major complication and the transient or long-term problems, ranging from mild to very severe, arising in non-cancerous tissues resulting from radiation treatment to a tumor of pelvic origin, are actually called as pelvic radiation disease. The incidence of pelvic radiation disease changes according to the radiation technique, the length of follow up, the assessment method, the type and stage of cancer and several other variables. Notably, even with the most recent radiation techniques, i.e., intensity-modulated radiotherapy, the incidence of radiation-induced GI side effects is overall reduced but still not negligible. In addition, radiation-induced GI side effects can develop even after several decades; therefore, the improvement of patient life expectancy will unavoidably increase the risk of developing radiation-induced complications. Once developed, the management of pelvic radiation disease may be challenging. Therefore, the prevention of radiation-induced toxicity represents a reasonable way to avoid a dramatic drop of the quality of life of these patients. In the current manuscript we provide an updated and practical review on the best available evidences in the field of the prevention of pelvic radiation disease. PMID:25664197

Fuccio, Lorenzo; Frazzoni, Leonardo; Guido, Alessandra

2015-02-01

466

Low level radiation: biological effects  

Microsoft Academic Search

It is imperative that physicians and scientists using radiations in health care delivery continue to assess the benefits derived, vs. potential risk, to patients and radiation workers being exposed to radiation in its various forms as part of our health delivery system. Insofar as possible we should assure our patients and ourselves that the benefits outweigh the potential hazards involved.

Loken

1983-01-01

467

Working With Radiation For Research  

E-print Network

1 Working With Radiation For Research Thomas Cummings Junior Physicist Environmental Health in the Form of Radiograph #12;6 Deleterious Effects on Early Radiation Workers #12;7 Represent energy roentgen (R) = 2.58 10-4 C/kg · Radiation Absorbed Dose: 1 rad = 10 mGray (Gy) · Equivalent or Effective

Jia, Songtao

468

Determination of the Soot Volume Fraction in an Ethylene Diffusion Flame by Multiwavelength Analysis of Soot Radiation  

Microsoft Academic Search

The features of the multiwavelength emission technique for the measurement of soot volume fraction and temperature in an ethylene diffusion flame have been investigated. For this purpose we have exploited the emission spectra from 300 nm to 800 nm and a mathematical Abel inversion procedure. To interpret the measurements, the quantity fv\\/Kabs = ?\\/(36?F(?)), here called natural length for absorption,

S. De Iuliis; M. Barbini; S. Benecchi; F. Cignoli; G. Zizak

1998-01-01

469

Space Radiation Cancer Risks  

NASA Technical Reports Server (NTRS)

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.

Cucinotta, Francis A.

2007-01-01

470

Lunar radiation environment  

NASA Astrophysics Data System (ADS)

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.

Schwadron, Nathan; Spence, Harlan; Wilson, Jody

471

Radiation Effects: Core Project  

NASA Technical Reports Server (NTRS)

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.

Dicello, John F.

1999-01-01

472

Pregnancy and Radiation Protection  

NASA Astrophysics Data System (ADS)

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.

Gerogiannis, J.; Stefanoyiannis, A. P.

2010-01-01

473

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)

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.

Popov, Dmitri; Jones, Jeffrey; Maliev, Slava

474

Radiation dosimetry and biophysical models of space radiation effects  

NASA Technical Reports Server (NTRS)

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.

Cucinotta, Francis A.; Wu, Honglu; Shavers, Mark R.; George, Kerry

2003-01-01

475

Radiation dosimetry and biophysical models of space radiation effects.  

PubMed

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. PMID:12959127

Cucinotta, Francis A; Wu, Honglu; Shavers, Mark R; George, Kerry