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1

Models of diffuse solar radiation  

Microsoft Academic Search

For some locations both global and diffuse solar radiation are measured. However, for many locations, only global is measured, or inferred from satellite data. For modelling solar energy applications, the amount of radiation on a tilted surface is needed. Since only the direct component on a tilted surface can be calculated from trigonometry, we need to have diffuse on the

John Boland; Barbara Ridley; Bruce Brown

2008-01-01

2

Diffuse galactic radiation  

NASA Astrophysics Data System (ADS)

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

Casandjian, Jean-Marc

2012-12-01

3

Diffuse gallium-67 uptake in radiation pneumonitis  

SciTech Connect

To evaluate the clinical usefulness of Ga-67 imaging for the assessment of radiation pneumonitis, 12 patients who had developed radiation pneumonitis after receiving radiotherapy alone for non-small-cell lung cancer from 1979 through 1988 were reviewed. Diffuse bilateral Ga-67 uptake occurred in 5 out of the 12 cases; in the other 7 cases, Ga-67 uptake was confined to the irradiation lung. Conversely, chest radiography showed infiltrates only in the irradiated lung. Histopathology of the lung in four out of the five cases that showed diffuse Ga-67 uptake in the lung, however, revealed that the lung outside the radiation field with Ga-67 uptake was consistent with interstitial pneumonitis induced by radiation. These results suggest that radiation pneumonitis could extend beyond the irradiated lung and that Ga-67 imaging is more useful than chest radiography for the assessment of the spatial extent of radiography pneumonitis.

Kataoka, M.; Kawamura, M.; Ueda, N.; Itoh, H.; Iio, A.; Hamamoto, K. (Ehime Univ. School of Medicine, Onsen-gun (Japan))

1990-10-01

4

Directive radiation from a diffuse Luneburg lens.  

PubMed

Transformation electromagnetics has opened possibilities for designing antenna structures. Using an analytical approach, we demonstrate here how directive antenna radiation can be achieved from an omnidirectional source behind a diffuse surface. This diffuse surface has been obtained by an optical transformation of a Luneburg lens. Two different transformation approaches have been proposed (polynomial and sinusoidal), and for both cases, the resulting material properties have been simplified to ease the fabrication by using all-dielectric media. Therefore, the proposed design has no upper boundary to the operational frequency. Directive radiation has been achieved from thin diffuse structures, which demonstrates promising future possibilities for this technique. PMID:23455079

Quevedo-Teruel, Oscar; Hao, Yang

2013-02-15

5

Climate, diffused solar radiation and multiple sclerosis.  

PubMed

Environmental factors implicated as affecting world-wide distribution of multiple sclerosis are reviewed. It is suggested that climate may be involved in the etiology of this disease. Diffused solar radiation effects on multiple sclerosis hospital admission rates are demonstrated. PMID:3051421

Laborde, J M; Dando, W A; Teetzen, M L

1988-01-01

6

Diffuse radiation, twilight, and photochemistry — I  

Microsoft Academic Search

A photochemical scheme which includes a detailed treatment of multiple scattering up to solar zenith angles of 96° (developed for use in a GCM) has been used to study partitioning within chemical families. Attention is drawn to the different zenith angle dependence of diffuse radiation for the two spectral regions ?310 nm. The effect that this has on the so-called

D. J. Lary; J. A. Pyle

1991-01-01

7

Diffusion of hydrogen radiation in prominences  

SciTech Connect

The interdependent integral equations of radiation diffusion in the H..cap alpha.., H..beta.., H..gamma.., P..cap alpha.., P..beta.., and B..cap alpha.. lines for a ''vertical slab'' in the solar radiation field have been solved on a computer in a new way: the unknown source functions were represented as Fourier series. Owing to the interrelation of the levels, the absorbed solar energy is redistributed: the brightness of the H..cap alpha.. line is increased by 25% while the H..beta.. and H..gamma.. lines are weakened by one third and one half, respectively, compared with the results of the simplified (two-level) problem (tau/sub 0/(H..cap alpha..) =10). The emission of prominences in the first Balmer lines is due to quasi-resonance scattering of photospheric radiation.

Yakovkin, N.A.; Zel'dina, M.Y.; Pavlenko, Y.V.

1979-09-01

8

Simulation of radiation belt electron diffusion  

NASA Astrophysics Data System (ADS)

This thesis presents theoretical and numerical studies of the radial diffusion of relativistic radiation belt electrons. The research has been focused particularly on the radiation belt phase space density profile, and radial diffusion due to particle drift resonance with ULF waves. Observations have shown a strong connection between magnetospheric ULF oscillations and electron flux enhancements. I investigate radial diffusion coefficients based on theoretical analysis of particle diffusion in ULF perturbation electric and magnetic fields. The analytical diffusion coefficients consist of two terms: a symmetric term and an asymmetric term. The symmetric term agrees with earlier works, and the asymmetric terms are new. Both terms show good agreement with numerical test particle simulations. The asymmetric terms have higher L dependence, which indicates they might be more important at higher L -shells or at times when the magnetospheric field is highly asymmetric. A numerical radial diffusion model has been developed which can take into account: dynamic boundary locations and values, plus effects of losses and sources. Several test cases are considered to study the effects of different diffusion coefficients, internal sources, external sources, and loss. A method of converting observational particle flux to phase space density is also presented. Identifying the source and loss processes using observational data is currently one of the key issues for understanding and modeling radiation belt dynamics. We present a new measurement technique which utilizes two GOES satellites located at different local times to calculate the radial gradient of phase space density at geostationary locations. The result shows positive gradient at geomagnetic quiet periods. To further study the high energy electron transport, especially the ULF related acceleration during storm times, I use the numerical radial diffusion model for the September 24-26, 1998 storm and compare the results with an MHD test particle simulation. The diffusion result using ULF-wave diffusion coefficients and a time-dependent outer-boundary condition can reproduce the main features of the MHD-particle results quite well. Using wave driven diffusion coefficients gives better results than using power law or Kp -dependent diffusion coefficients.

Fei, Yue

2007-02-01

9

Diffusion in potato during far infrared radiation drying  

Microsoft Academic Search

The effect of radiation intensity and thickness of slab on the moisture diffusion characteristics of potato during FIR drying is investigated. The standard solution to the non-stationary state diffusion equation was used as a mathematical tool. A model fitting procedure was applied to the experimental drying data to determine the diffusion coefficients. The diffusivity was found to vary with radiation

T. M. Afzal; T. Abe

1998-01-01

10

Gas phase radiative effects in diffusion flames  

NASA Astrophysics Data System (ADS)

Several radiation models are evaluated for a stagnation point diffusion flame of a solid fuel in terms of accuracy and computational time. Narrowband, wideband, spectral line weighted sum of gray gases (SLWSGG), and gray gas models are included in the comparison. Radiative heat flux predictions by the nongray narrowband, wideband, and SLWSGG models are found to be in good agreement with each other, whereas the gray gas models are found to be inaccurate. The narrowband model, the most complex among the models evaluated, is then applied first to a solid fuel and second to a pure gaseous diffusion flame. A polymethylmethacrylate (PMMA) diffusion flame in a stagnation point geometry is solved with the narrowband model with COsb2, Hsb2O, and MMA vapor included in participating species. A detailed account of the emission and absorption from these species as well as the radiative heat fluxes are given as a function of the stretch rate. It is found that at low stretch rate the importance of radiation is increased due to an increase in the optical thickness, and a decrease in the conductive heat flux. Results show that COsb2 is the biggest emitter and absorber in the flame, MMA vapor is the second and Hsb2O is the least important. A pure gaseous flame in an opposed jet configuration is solved with the narrowband radiation model with CO as the fuel, and Osb2 as the oxidizer. Detailed. chemical kinetics and transport are incorporated into the combustion model with the use of the CHEMKIN and TRANSPORT software packages. The governing equations are solved with a modified version of the OPPDIF code. Dry and wet CO flames as well as COsb2 dilution are studied. Comparison of the results with and without the consideration of radiation reveals that the radiation is important for the whole flammable range of dry CO flames and for the low stretch rates of wet flames. Without the consideration of radiation the temperature and the species mole fractions (especially of minor species) predictions are different in comparison to the results with the inclusion of the radiation in the model. A flammability map with added Hsb2O fraction and stretch rate as coordinates is drawn. The flammability map contains a blow off extinction boundary at high stretch rate and a quenching extinction boundary at low stretch rate. With increasing Hsb2O addition the quenching boundary shifts to lower stretch rates and the blow off boundary shifts to higher stretch rates, hence the range of flammable stretch rates increases. COsb2 dilution of the fuel (CO) jet is found to decrease the flame temperature. A flammability map with COsb2 mole fraction in the fuel jet and the stretch rate as coordinates is also drawn. With increasing COsb2 dilution the range of flammable stretch rate decreases. For the dry CO-Osb2 case, when COsb2 dilution exceeds 17%, the system is nonflammable for any stretch rate. The most flammable stretch rate is around 2 ssp{-1}.

Bedir, Hasan

11

Adaptive Implicit Non-Equilibrium Radiation Diffusion  

NASA Astrophysics Data System (ADS)

We describe methods for accurate and efficient long term time integration of non-equilibrium radiation diffusion systems: implicit time integration for efficient long term time integration of stiff multiphysics systems, local control theory based step size control to minimize the required global number of time steps while 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.

Philip, B.; Wang, Z.; Berrill, M.; Rodriguez, M.; Pernice, M.

2013-04-01

12

Adaptive Implicit Non-Equilibrium Radiation Diffusion  

SciTech Connect

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

Philip, Bobby [ORNL; Wang, Zhen [ORNL; Berrill, Mark A [ORNL; Rodriguez Rodriguez, Manuel [ORNL; Pernice, Michael [Idaho National Laboratory (INL)

2013-01-01

13

Stochastic modeling of multidimensional diffusion in the radiation belts  

Microsoft Academic Search

A new code for solving radiation belt diffusion equations has been developed and applied to the 2-D bounce-averaged energy pitch angle quasi-linear diffusion equation. The code uses Monte Carlo methods to solve Itô stochastic differential equations (SDEs) which are mathematically equivalent to radiation belt diffusion equations. We show that our SDE code solves the diffusion equation with off-diagonal diffusion coefficients

Xin Tao; Anthony A. Chan; Jay M. Albert; James A. Miller

2008-01-01

14

A note on diffuse solar radiation on a tilted surface  

Microsoft Academic Search

We are presenting a note on comparative study of diffuse component of solar radiation on tilted surface with different angle of inclination. The monthly mean daily diffuse radiation have been calculated on inclined surfaces from the data of horizontal surface using the Circumsolar and Isotropic model and the anisotropic model of Klucher and Hay at Lucknow (Latitude 26.75°, Longitude 80.85°),

Chanchal Kumar Pandey; A. K. Katiyar

2009-01-01

15

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

16

A comparison of several diffuse solar radiation models for Greece  

Microsoft Academic Search

This paper attempts to test the applicability of existing correlation models to the estimation of diffuse radiation with respect to measured values at a station. There are two types of model: The first type depends on the fraction of monthly average daily diffuse radiation to total solar radiation,\\u000a$$K = {{\\\\bar H_d } \\\\mathord{\\\\left\\/ {\\\\vphantom {{\\\\bar H_d } {\\\\bar H}}}

B. D. Katsoulis

1991-01-01

17

Diffuse, global and extra-terrestrial solar radiation for Singapore  

Microsoft Academic Search

In this paper, equations have been developed to estimate diffuse fraction of the hourly, daily and monthly global insolation on a horizontal surface. These correlations are expressed in terms of Kd, the ratio of diffuse-to-total radiation, and KT, the clearness index. The hourly correlation equations, show a fairly similar trend to that of Orgill and Hollands (1) and Spencer (5)

M. N. A. Hawlader

1984-01-01

18

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

19

Diffusion tensor imaging of the optic radiations after optic neuritis.  

PubMed

Trans-synaptic degeneration could exacerbate neurodegeneration in multiple sclerosis (MS). We aimed to assess whether anterograde trans-synaptic degeneration could be identified in the primary visual pathway in vivo. Diffusion tensor imaging (DTI) was used to assess the optic radiations in 15 patients with previous optic nerve inflammation and 9 healthy volunteers. A probabilistic atlas of the optic radiations was created from healthy diffusion tractography data. Lengthwise profiles for DTI parameters (axial [?(||) ], radial [?(?) ] and mean diffusivity [MD], fractional anisotropy [FA] and the angle of deviation of the principal eigenvector [?]) were analyzed for patients and controls. Patients also underwent multifocal visual evoked potential (mfVEP) assessments to characterize the latency and amplitude of cortical potentials. Correlations were performed between mfVEP latency and amplitude in the left and right visual hemi-fields and DTI parameters in the contra-lateral optic radiations. Patients displayed a significant decrease in ?(||) within the body of both optic radiations, which significantly correlated with loss of mfVEP amplitude. Abnormal ?(?) and FA were detected bilaterally throughout the optic radiations in patients but the abnormality was not associated with amplitude reduction or latency prolongation of the mfVEP. An abnormal ? value was observed in the left optic radiations of patients, and the ? value in the body of the optic radiations also correlated with mfVEP amplitude loss. The assocation between bilateral DTI abnormalities within the optic radiations and loss of afferent electrical activity could indicate anterograde trans-synaptic degeneration occurs following optic neuritis. PMID:21915943

Kolbe, Scott; Bajraszewski, Clare; Chapman, Caron; Nguyen, Tan; Mitchell, Peter; Paine, Mark; Butzkueven, Helmut; Johnston, Leigh; Kilpatrick, Trevor; Egan, Gary

2011-09-13

20

Modelling Thermally Radiating Diffusion Flames with Detailed Chemistry and Transport.  

National Technical Information Service (NTIS)

Strained laminar counterflow-diffusion flames of CO-H2-N2 mixtures in air are numerically simulated using detailed models for thermal radiation, chemistry and molecular transport. The overall model is validated by comparison of the numerical results with ...

Y. Liu B. Rogg

1990-01-01

21

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

22

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

23

Diffusion Models for Jupiter'S Radiation Belt.  

National Technical Information Service (NTIS)

Solutions are given for the diffusion of trapped particles in a planetary magnetic field in which the first and second adiabatic invariants are preserved but the third is not, using as boundary conditions a fixed density at the outer boundary (the magneto...

L. Davis S. A. Jacques

1972-01-01

24

Shadow-band correction for diffuse ultraviolet radiation measurements  

NASA Astrophysics Data System (ADS)

the correction of shadow-band solar total diffuse measurements has been extensively studied, the case of diffuse ultraviolet measurements has not been properly addressed. This study analyzes the correction factor to be applied to experimental measurements performed adapting a shadow-band to a UV radiometer at a radiometric station in Badajoz (Spain). Three different models, based on approaches widely used for correcting total diffuse measurements, have been revised and adapted for the ultraviolet spectral range. Results reveal that some aspects of the correction proposed for total diffuse radiation are not suitable for ultraviolet diffuse radiation. The mathematical expressions are consequently modified to match the behavior in the ultraviolet range. Thus, three correction models particularized for ultraviolet diffuse measurements are proposed and validated against experimental data. The two models adapted from the original expressions proposed by Battles et al., and Steven show the best performance, with rRMSE of 2.74% and 2.20% and rMBE of 1.53% and 0.46%, respectively.

SáNchez, G.; Serrano, A.; Cancillo, M. L.

2013-05-01

25

Diffusion and recombination of products of ionizing radiations  

Microsoft Academic Search

The relative importance of diffusion and recombination of the products of ionizing radiations is examined in several typical\\u000a cases and methods for the solution of the differential equation of columnar ionization are discussed. It is shown that Jaff's\\u000a method is not applicable to radiobiological or purely radiochemical processes in which no external electric fields are acting.\\u000a A method based on

I. Opatowski; F. R. Tangherlini

1951-01-01

26

Synchrotron radiation study of diffusion in FeAl  

Microsoft Academic Search

Nuclear resonance scattering of synchrotron radiation has been used to determine the elementary diffusion jump in the ordered\\u000a stoichiometric alloy FeAl. To that aim the intensity decay in forward direction is measured as a function of crystal orientation.\\u000a A decision between various jump models confirms earlier results from classical quasielastic Mssbauer spectroscopy, but with\\u000a considerably better angular resolution.

B. Sepiol; C. Czihak; A. Meyer; G. Vogl; J. Metge; R. Rüffer

1998-01-01

27

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

28

Consistent Solar Evolution Model Including Diffusion and Radiative Acceleration Effects  

SciTech Connect

The solar evolution has been calculated including all the effects of the diffusion of helium and heavy elements. Monochromatic opacities are used to calculate radiative accelerations and Rosseland opacities at each evolution time step, taking into account the local abundance changes of all important (21) chemical elements. The OPAL monochromatic data are used for the opacities and the radiative accelerations. The Opacity Project data are needed to calculate how chemical species and electrons share the momentum absorbed from the radiation flux. A detailed evaluation of the impact of atomic diffusion on solar models is presented. On some elements thermal diffusion adds approximately 50{percent} to the gravitational settling velocity. While gravitational settling had been included in previous solar models, this is the first time that the impact of radiative accelerations is considered. Radiative accelerations can be up to 40{percent} of gravity below the solar convection zone and thus affect chemical element diffusion significantly, contrary to current belief. Up to the solar age, the abundances of most metals change by 7.5{percent} if complete ionization is assumed, but by 8.5{percent}{endash}10{percent} if detailed ionization of each species is taken into account. If radiative accelerations are included, intermediate values are obtained. Diffusion leads to a change of up to 8{percent} in the Rosseland opacities, compared to those of the original mixture. Most of this effect can be taken into account by using tables with several values of {ital Z}. If one isolates the effects of radiative accelerations, the abundance changes they cause alter the Rosseland opacity by up to 0.5{percent}; the density is affected by up to 0.2{percent}; the sound speed is affected by at most 0.06{percent}. The inclusion of radiative accelerations leads to a reduction of 3{percent} of neutrino fluxes measured with {sup 37}Cl detectors and 1{percent} measured with {sup 71}Ga detectors. The partial transformation of C and O into N by nuclear reactions in the core causes a {approximately}1{percent} change in the opacities that cannot be modeled by a change in {ital Z} alone. The evolution is allowed to proceed to 10{sup 10} yr in order to determine the impact at the end of the main-sequence life of solar-type stars. It is found that immediately below the convection zone, the radiative acceleration on some iron peak elements is within a few percent of gravity. The abundance anomalies reach 18{percent} for He in the convection zone but are kept within 12{percent} and 15{percent} for most because of {ital g}{sub rad}. They would have reached 18{percent} in the absence of {ital g}{sub rad}. {copyright} {ital {copyright} 1998.} {ital The American Astronomical Society}

Turcotte, S. [Departement de physique, Universite de Montreal, Montreal, Quebec H3C 3J7 (Canada)]|[Teoretisk Astrofysik Center, Aarhus Universitet, DK-8000, Aarhus C (Denmark); Richer, J. [Centre de Recherche en Calcul Applique (CERCA), 5160 boulevard Decarie, bureau 400, Montreal, PQ H3X 2H9 (Canada); Michaud, G. [Centre de Recherche en Calcul Applique (CERCA), 5160 boulevard Decarie, bureau 400, Montreal, PQ H3X 2H9 (Canada)]|[Departement de Physique, Universite de Montreal, Montreal, PC H3C 3J7 (Canada); Iglesias, C.A.; Rogers, F.J. [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, CA 94550 (United States)

1998-09-01

29

Observations of the diffuse near-UV radiation field  

NASA Astrophysics Data System (ADS)

The diffuse radiation field from 1650-3100 A has been observed by spectrometer aboard the Space Shuttle, and the contributions of the zodiacal light an the diffuse cosmic background to the signal have been derived. Colors ranging from 0.65 to 1.2 are found for the zodiacal light with an almost linear increase in the color with ecliptic latitude. This rise in color is due to UV brightness remaining almost constant while the visible brightnesses drop by almost a factor of two. This is interpreted as evidence that the grains responsible for the UV scattering have much more uniform distribution with distance from the ecliptic plane than do those grains responsible for the visible scattering. Intensities for the cosmic diffuse background ranging from 300 units to 900 units are found which are not consistent with either a correlation with N(H I) or with spatial isotropy.

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

1990-05-01

30

Radiation enhanced diffusion of Ti in Al2O3  

NASA Astrophysics Data System (ADS)

Titanium bulk and dislocation diffusion coefficients at 1000 °C have been determined for Ti in single crystal ?-Al2O3(0001) for three types of samples: (i) Ti evaporated onto Al2O3, (ii) 48Ti+at 100 eV deposited onto Al2O3, and (iii) 48Ti+ at 100 eV deposited onto radiation damaged Al2O3 (damage inflected by implantation of 46Ti+ at 7 keV). Diffusion penetration profiles were obtained by using secondary ion mass spectrometry depth profiling techniques. For the deposited and implanted Ti+ samples, the bulk diffusion coefficients (D) are 5.4×10-21 and 5.6×10-17 m2 s-1, respectively, and dislocation diffusion coefficients are 3.6×10-17 and 1.4×10-12 m2 s-1, respectively. Comparing the D's for Ti in the undamaged and damaged Al2O3, the D's for the latter samples are higher by a factor of 104-105, reflecting the radiation enhanced diffusion due to the defect structure inflected by the implanted 7 keV 46Ti+. Comparing the D's for Ti deposited onto Al2O3 (both the evaporated and 100 eV 48Ti+ samples) with those for Cr deposited onto Al2O3, the Ti D's are larger by a factor of 10, reflecting the influence of the valence state of the cation. These results show that cationic diffusion coefficients in Al2O3 can be controlled by varying the level of defects in the crystal.

Weiss, M.; Lu, M.; van der Heide, P.; Lee, S. M.; Ada, E.; Lee, H. S.; Rabalais, J. W.

2000-09-01

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)]|[Universite de Savoie, BP1104, 73011 Chambery Cedex (France); Salati, P. [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); Grenier, I. [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)

1995-12-01

32

Extraction and analysis of diffuse UV radiation from GALEX observations  

NASA Astrophysics Data System (ADS)

Using the GALEX observations available over the web, we are probing diffuse UV background radiation in FUV and NUV. Each GALEX field consist of stars, galaxies and diffuse UV radiations like airglow, zodiacal light (especially in NUV), star light scattered from interstellar dust, etc. In this poster we describe our method to extract the diffuse UV background and its components from the GALEX fields and the preliminary results we have derived from correlation studies, using four nearby Deep Imaging Survey (DIS) targets (DR1 - DIS 8-11). Even though all the 4 DIS targets are observed from the neighbouring regions, the correlation studies show different results i.e., there is a strong correlation between FUV and NUV as well as between FUV(NUV) and IR in the DIS 8 region, suggesting that except for the non-zero intercept values (600 and 1050 photons /cm2/s/sr/ in FUV and NUV), what we are seeing in the field is star light scattered from interstellar dust. In DIS 9 region, there is absolutely no correlation in either case, suggesting that there is no dust scattered radiation, but ofcourse this region is almost free from dust. In DIS 10 and 11 regions, both the correlations are week compared to DIS 8. But in all the 4 regions (and many other GALEX DIS locations), there is a strong level of non-zero intercept in FUV and NUV, (for e.g., in DIS 9 region, 950 PU in FUV and 1350 PU in NUV), which cannot be attributed to dust scattered starlight. For these amount in FUV, (in NUV almost half of this is zodiacal light), we do not have proper explanations at this point of time,! However comparing FUV and NUV correlation plots with IR (note that FUV and NUV plots are not following the same pattern), the apparent reduction of NUV intensity with increase in the amount of dust seems to point to an extragalactic contribution in the regions. So some part of the unexplained radiation could be attributed to this.

Sujatha, N. V.; Murthy, Jayant; Henry, R. C.

33

A consistent approach to solving the radiation diffusion equation  

NASA Astrophysics Data System (ADS)

Diffusive x-ray-driven heat waves are found in a variety of astrophysical and laboratory settings, e.g. in the heating of a hohlraum used for ICF, and hence are of intrinsic interest. However, accurate analytic diffusion wave (also called Marshak wave) solutions are difficult to obtain due to the strong non-linearity of the radiation diffusion equation. The typical approach (used by Marshak himself) is to solve near the heat front, and by ansatz apply the solution globally. This approach works fairly well due to Â"steepnessÂ" of the heat front, but energy is not conserved and it does not lead to a consistent way of correcting the solution or estimating accuracy. We employ the steepness of the front through a perturbation expansion in ? = ?/(4+?), where the specific heat varies as T^? and the opacity varies as T^-?, then match outer (away from the front) and inner (near the front) solutions. Typically ? < 0.3. Calculations are through first order in ? and are accurate to 10%, which is comparable to the inaccuracy from assuming power laws for material properties. We solve for supersonic waves with arbitrary drive time history, including the case of a cooling surface, and for subsonic waves with drive temperature varying as a power of time. In the subsonic case, the specific heat, (pressure/density) and opacity are each assumed to vary as density to a small power, of order ?. We find the theory compares well with radiation hydrodynamics code calculations of the heat front position, absorbed flux and ablation pressure. Including the Milne effect, the theory gives accurate values for hohlraum wall albedoes and the angle-dependent emission of a heated surface.

Hammer, James

2002-11-01

34

A Consistent Approach to Solving the Radiation Diffusion Equation  

SciTech Connect

Diffusive x-ray-driven heat waves are found in a variety of astrophysical and laboratory settings, e.g. in the heating of a hohlraum used for ICF, and hence are of intrinsic interest. However, accurate analytic diffusion wave (also called Marshak wave) solutions are difficult to obtain due to the strong non-linearity of the radiation diffusion equation. The typical approach is to solve near the heat front, and by ansatz apply the solution globally. This works fairly well due to ''steepness'' of the heat front, but energy is not conserved and it does not lead to a consistent way of correcting the solution or estimating accuracy. We employ the steepness of the front through a perturbation expansion in {var_epsilon} = {beta}/(4+{alpha}), where the internal energy varies as T{sup {beta}} and the opacity varies as T{sup -{alpha}}. We solve using an iterative approach, equivalent to asymptotic methods that match outer (away from the front) and inner (near the front) solutions. Typically {var_epsilon} < 0.3. Calculations are through first order in {var_epsilon} and are accurate to {approx} 10%, which is comparable to the inaccuracy from assuming power laws for material properties. We solve for supersonic waves with arbitrary drive time history, including the case of a rapidly cooling surface, and generalize the method to arbitrary temperature dependence of opacity and internal energy. We also solve for subsonic waves with drive temperature varying as a power of time. In the subsonic case, the specific heat, (pressure/density) and opacity are each assumed to vary as density to a small power, of order {var_epsilon}. We find the theory compares well with radiation hydrodynamics code calculations of the heat front position, absorbed flux and ablation pressure.

Hammer, J H; Rosen, M D

2002-11-06

35

A consistent approach to solving the radiation diffusion equation  

NASA Astrophysics Data System (ADS)

Diffusive x-ray-driven heat waves are found in a variety of astrophysical and laboratory settings, e.g., in the heating of a hohlraum used for inertial confinement fusion, and hence are of intrinsic interest. However, accurate analytic diffusion wave (also called Marshak wave) solutions are difficult to obtain due to the strong nonlinearity of the radiation diffusion equation. The typical approach is to solve near the heat front, and by ansatz apply the solution globally. This approach works fairly well due to ``steepness'' of the heat front, but energy is not conserved and it does not lead to a consistent way of correcting the solution or estimating accuracy. In this work, the steepness of the front is employed through a perturbation expansion in ?=?/(4+?), where the internal energy varies as T? and the opacity varies as T-?. The equations are solved using an iterative approach, equivalent to asymptotic methods that match outer (away from the front) and inner (near the front) solutions. Typically V<0.3. Calculations through first order in V and are accurate to ~10%, which is comparable to the inaccuracy from assuming power laws for material properties. Supersonic waves with arbitrary drive time history are solved for, including the case of a rapidly cooling surface. The method is then generalized to arbitrary temperature dependence of opacity and internal energy. Also solved for are subsonic waves with drive temperature varying as a power of time. In the subsonic case, the specific heat (pressure/density) and opacity are each assumed to vary as density to a small power, of order V. Solutions are obtained through order V2 and it is found that the theory compares well with radiation hydrodynamics code calculations of the heat front position, absorbed flux, and ablation pressure.

Hammer, James H.; Rosen, Mordecai D.

2003-05-01

36

The Calculation of Diffuse Radiation on a Horizontal Surface for Solar Energy Applications  

Microsoft Academic Search

To analyze the systems working with solar energy, it is required that values of the solar radiation belonging to the region have been known. The global solar radiation on a horizontal surface has been measured by the Turkish State Meteorological Service over all of the country, while the diffuse solar radiation has not been measured. In this study, empirical correlations

K. Bakirci

2012-01-01

37

Penetration of diffuse ultraviolet radiation into interstellar clouds  

SciTech Connect

We show that the solution of the transfer equation appropriate for models of the penetration of diffuse UV radiation into interstellar clouds, subject to attenuation by coherent, nonconservative, anisotropic scattering from grains, can be expressed analytically, with arbitrary accuracy, by means of the spherical harmonics method. Models of plane-parallel and homogeneous spherical clouds are given as functions of three parameters: tau/sub c/ the central optical depth, ..omega.. the single scattering albedo, and g the parameter in the Henyey-Greenstein phase function. These models qualitatively confirm the results of earlier Monte Carlo simulations of dust scattering, but reveal quantitative discrepancies: the earlier results overestimated the actual mean intensity, often by more than an order of magnitude.

Flannery, B.P.; Roberge, W.; Rybicki, G.B.

1980-03-01

38

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

39

Diffuse solar radiation-daily and monthly values as affected by snow cover  

SciTech Connect

It is generally recognized that surface albedo (terrain reflectance) has a significant effect on the diffuse fraction of global radiation. In colder climates, ground snow cover could be expected to alter the terrain reflectance significantly. The objective of this paper was to study the effect of ground snow cover on the diffuse fraction of the daily and the monthly average global radiation and to develop empirical relationships which would permit the calculation of the diffuse solar component.

Kierkus, W.T.; Colborne, W.G. (Univ. of Windsor, Ontario (Canada))

1989-01-01

40

A comparison of discrete-ordinates and flux-limited-diffusion methods for modeling radiation transport in radiative shock tubes  

NASA Astrophysics Data System (ADS)

The Center for Radiative Shock Hydrodynamics (CRASH) seeks to improve the predictive capability for models of Omega laser experiments of radiative shock waves. The laser is used to shock, ionize, and accelerate a beryllium plate into a xenon-filled shock tube. These shocks, when driven above a threshold velocity of about 60 km/s, become strongly radiative and convert most of the incoming energy flux into radiation. Radiative shocks have properties that are significantly different from purely hydrodynamic shocks and, in modeling this phenomenon numerically, it is important to compute radiative effects accurately. In this presentation, we examine approaches to modeling radiation transport by comparing two methods: (i) a computationally efficient approximation (multigroup flux-limited diffusion), currently in use in the CRASH code, with (ii) a more accurate discrete-ordinates treatment that is offered by the code PDT. We present a selection of results from a suite of comparison tests, showing both idealized problems and those that are representative of conditions found in the CRASH experiment.

Myra, Eric S.; Hawkins, Wm. Daryl

2011-11-01

41

Increased diffuse radiation fraction does not significantly accelerate plant growth  

NASA Astrophysics Data System (ADS)

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

Angert, Alon; Krakauer, Nir

2010-05-01

42

Diffusive radiation in one-dimensional Langmuir turbulence.  

PubMed

We calculate spectra of radiation produced by a relativistic particle in the presence of one-dimensional Langmuir turbulence which might be generated by a streaming instability in the plasma, in particular, in the shock front or at the shock-shock interactions. The shape of the radiation spectra is shown to depend sensitively on the angle between the particle velocity and electric field direction. The radiation spectrum in the case of exactly transverse particle motion is degenerate and similar to that of spatially uniform Langmuir oscillations. In the case of oblique propagation, the spectrum is more complex, it consists of a number of power-law regions and may contain a distinct high-frequency spectral peak. The emission process considered is relevant to various laboratory plasma settings and for astrophysical objects as gamma-ray bursts and collimated jets. PMID:17677604

Fleishman, G D; Toptygin, I N

2007-07-10

43

Diffusion in a crystal lattice with nuclear resonant scattering of synchrotron radiation  

Microsoft Academic Search

We report on a method for probing the elementary diffusion jumps in crystalline lattices on an atomistic scale. The method makes use of synchrotron radiation coherently scattered in the forward direction after nuclear resonant excitation. The decay of forward-scattered radiation is faster (``diffusionally accelerated'') when atoms move on the time scale of the excited-state lifetime because of a loss of

B. Sepiol; A. Meyer; G. Vogl; H. Franz; R. Rüffer

1998-01-01

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

The influence of artificial radiation damage and thermal annealing on helium diffusion kinetics in apatite  

Microsoft Academic Search

Recent work [Shuster D. L., Flowers R. M. and Farley K. A. (2006) The influence of natural radiation damage on helium diffusion kinetics in apatite. Earth Planet. Sci. Lett.249(3–4), 148–161] revealing a correlation between radiogenic 4He concentration and He diffusivity in natural apatites suggests that helium migration is retarded by radiation-induced damage to the crystal structure. If so, the He

David L. Shuster; Kenneth A. Farley

2009-01-01

46

Consistent Approach to Solving the Radiation Diffusion Equation.  

National Technical Information Service (NTIS)

Radiation heat waves, or Marshak waves, play an important role in energy transport for many astrophysical and laboratory plasmas. Of particular interest is the role of Marshak waves in the energy balance of laser, z-pinch and heavy ion beam hohlraums for ...

J. H. Hammer M. D. Rosen

2002-01-01

47

Time Domain Study of 57Fe Diffusion using Nuclear Forward Scattering of Synchrotron Radiation  

Microsoft Academic Search

Diffusion of 57Fe in the intermetallic alloy Fe3Si was investigated using nuclear forward scattering of synchrotron radiation parallel to the [113] crystal direction with the aim to demonstrate the feasibility of a diffusion study in a crystalline solid. The jumps between different sites on a lattice, corresponding to a finite residence time on one and the same lattice site, cause

B. Sepiol; A. Meyer; G. Vogl; R. Rüffer; A. I. Chumakov; A. Q. R. Baron

1996-01-01

48

Effects of diffuse radiation on canopy gas exchange processes in a forest ecosystem  

NASA Astrophysics Data System (ADS)

Forest ecosystems across the globe show an increase in ecosystem carbon uptake efficiency under conditions with high fraction of diffuse radiation. Here, we combine eddy covariance flux measurements at a deciduous temperate forest in central Germany with canopy-scale modeling using the biophysical multilayer model CANVEG to investigate the impact of diffuse radiation on various canopy gas exchange processes and to elucidate the underlying mechanisms. Increasing diffuse radiation enhances canopy photosynthesis by redistributing the solar radiation load from light saturated sunlit leaves to nonsaturated shade leaves. Interactions with atmospheric vapor pressure deficit and reduced leaf respiration are only of minor importance to canopy photosynthesis. The response strength of carbon uptake to diffuse radiation depends on canopy characteristics such as leaf area index and leaf optical properties. Our model computations shows that both canopy photosynthesis and transpiration increase initially with diffuse fraction, but decrease after an optimum at a diffuse fraction of 0.45 due to reduction in global radiation. The initial increase in canopy photosynthesis exceeds the increase in transpiration, leading to a rise in water-use-efficiency. Our model predicts an increase in carbon isotope discrimination with water-use-efficiency resulting from differences in the leaf-to-air vapor pressure gradient and atmospheric vapor pressure deficit. This finding is in contrast to those predicted with simple big-leaf models that do not explicitly calculate leaf energy balance. At an annual scale, we estimate a decrease in annual carbon uptake for a potential increase in diffuse fraction, since diffuse fraction was beyond the optimum for 61% of the data.

Knohl, Alexander; Baldocchi, Dennis D.

2008-06-01

49

Diffuse Galactic Radiation and its Application to CMB Observations  

NASA Astrophysics Data System (ADS)

In this thesis I describe work related to the investigation of CMB foregrounds, particularly at frequencies of ? 30 GHz where the Very Small Array (VSA) operates. During the commissioning period at Tenerife, the VSA was shown to approach the theoretical sensitivity. The first season (1 year) of CMB observations measures the ?-range 150-900. The first peak in the CMB power spectrum is clearly detected at ? ? 220 with ? T ? 80 ?K and there is evidence for a second peak at ? ? 550. At higher ?, the fluctuations drop in amplitude to ? 30 ?K at ? ? 800, in agreement with current inflationary cosmologies. The VSA results agree exceptionally well with other recent CMB experiments (BOOMERanG, MAXIMA, DASI, CBI). With priors from type Ia supernovae data, we find ?_{b}h^{2}=0.029_{-0.009}^{+0.009}, n_{s}=1.02_{-0.06}^{+0.12}, ?_{tot}=1.02_{-0.06}^{+0.08}, ?_{cdm}h^{2}=0.09_{-0.04}^{+0.05}, ?_{m}=0.32_{-0.06}^{+0.09} and ?_{?}=0.71_{-0.07}^{+0.07}. Foreground contamination from residual discrete radio sources is calculated to be less than 2.5% tep{Scott02}. This is achieved by measuring at the same frequency and time, the brightest sources in each VSA region using a dedicated source-subtraction baseline. We have opted to observe at a single frequency therefore it is critical to know the amplitude of Galactic emission. The contamination from diffuse Galactic radiation is calculated to be ? 5 ?K at angular scales of 1° using r.m.s. predictions from foreground maps. Further to this, I have developed a cross-correlation method to calculate the correlation of the interferometer data with foreground maps. I find no correlation with the 100 ?m map tep{Schlegel98}, with an upper limit of 0.84 ?K (2?) in the VSA data. A full-sky H? map at 1deg; resolution is produced by combining data from the WHAM and SHASSA surveys; the H? line is well-known to be a good tracer of free-free emission. A quantitative method of calculating the absorption of H? by dust is given, based on the 100 ?m maps of tet{Schlegel98}. The greatest uncertainty is the fraction of dust, f_{d}, along the line of sight actually absorbing. The conversion from H? to radio free-free continuum is re-evaluated and equations in the literature are corrected. The conversion can be applied to produce free-free template maps for frequencies 1-1000 GHz with a precision of ? 10%. The free-free template is tested for several regions of the sky using low frequency data. The free-free estimates appear to be too large by up to ˜ 30%. This can be largely explained by variations in the electron temperature. At high Galactic latitudes (|b|>20°), the 408 MHz synchrotron map has ˜ 6% in the form of free-free emission; the correction is therefore important. Finally, the power spectrum of H?/free-free seems to be much flatter (power-law index of ? 2) than previously thought, but is well below the CMB anisotropy for ?=10-70. I also describe work associated with the Manchester Wide-Field Camera (MWFC). The MWFC has a 32° field of view with 7 arcmin resolution which allows large-scale (? 1°) nebulosities to be imaged. H? observations of the Eridanus region are presented and the correlations with the far infrared and X-ray emission are described. There is evidence for a superposition of H? shells along the line of sight. The camera has been modified to allow stand-alone operation using its own mount and CCD.

Dickinson, Clive

2002-10-01

50

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

NASA Astrophysics Data System (ADS)

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

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

2008-08-01

51

A Multidimensional Radiation Magnetohydrodynamics Code Based on Flux-Limited Diffusion and HLLD  

NASA Astrophysics Data System (ADS)

We present a multidimensional radiation magnetohydrodynamics (MHD) code based on the high-resolution shock capturing schemes (HRSC), the flux-limited diffusion (FLD) approximation, and the assumption of local thermodynamic equilibrium (LTE). The HRSC, employing a conservative algorithm that accurately ensures conservation of the total energy of MHD is implemented using a third-order Runge-Kutte scheme and the HLLD Riemann solver. In the FLD approximation, because the evolution equations of the radiation energy flux are neglected, this code is easily implemented, though the FLD approximation is less accurate when dealing with highly anisotropic radiation fields in an optically thin region. We carried out classical tests for the MHD and for the subcritical and supercritical radiating shocks. The results show that this code can achieve the necessary accuracy and efficiency to solve the radiation-dominated astrophysical processes with the FLD approximation.

Yang, Xiaohong; Yuan, Feng

2012-08-01

52

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

53

Effect of radiative heat loss on diffusion flames in quiescent microgravity atmosphere  

Microsoft Academic Search

This paper presents the results of theoretical calculations for radiation-induced extinction of one-dimensional unsteady diffusion flames in a quiescent microgravity environment. The model formulation includes both gas and soot radiation. Soot volume fraction is not a priori assumed, instead it is produced and oxidized according to the temperature- and species-dependent formation and oxidation rates. Thus, soot volume fraction and the

Arvind Atreya; Sanjay Agrawal

1998-01-01

54

Terahertz emission by diffusion of carriers and metal-mask dipole inhibition of radiation  

NASA Astrophysics Data System (ADS)

Terahertz (THz) radiation can be generated by ultrafast photo-excitation of carriers in a semiconductor partly masked by a gold surface. A simulation of the effect taking into account the diffusion of carriers and the electric field shows that the total net current is approximately zero and cannot account for the THz radiation. Finite element modelling and analytic calculations indicate that the THz emission arises because the metal inhibits the radiation from part of the dipole population, thus creating an asymmetry and therefore a net current. Experimental investigations confirm the simulations and show that metal-mask dipole inhibition can be used to create THz emitters.

Barnes, M. E.; McBryde, D.; Daniell, G. J.; Whitworth, G.; Chung, A. L.; Quarterman, A. H.; Wilcox, K. G.; Brewer, A.; Beere, H. E.; Ritchie, D. A.; Apostolopoulos, V.

2012-04-01

55

Diffusive, supersonic x-ray transport in radiatively heated foam cylinders  

NASA Astrophysics Data System (ADS)

Diffusive supersonic radiation transport, where the ratio of the diffusive radiation front velocity to the material sound speed >2 has been studied in experiments on low density (40 mg/cc to 50 mg/cc) foams. Laser-heated Au hohlraums provided a radiation drive that heated SiO2 and Ta2O5 aerogel foams of varying lengths. Face-on emission measurements at 550 eV provided clean signatures of the radiation breakout. The high quality data provides new detailed information on the importance of both the fill and wall material opacities and heat capacities in determining the radiation front speed and curvature. The Marshak radiation wave transport is studied in a geometry that allows direct comparisons with analytic models and two-dimensional code simulations. Experiments show important effects that will affect even nondiffusive and transonic radiation transport experiments studied by others in the field. This work is of basic science interest with applications to inertial confinement fusion and astrophysics.

Back, C. A.; Bauer, J. D.; Hammer, J. H.; Lasinski, B. F.; Turner, R. E.; Rambo, P. W.; Landen, O. L.; Suter, L. J.; Rosen, M. D.; Hsing, W. W.

2000-05-01

56

Effects of energy and pitch angle mixed diffusion on radiation belt electrons  

NASA Astrophysics Data System (ADS)

Understanding the dynamics of the Earth’s radiation belts is important for modeling and forecasting the intensities of energetic electrons in space. Wave diffusion processes are known to be responsible for loss and acceleration of electrons in the radiation belts. Several recent studies indicate pitch angle and energy mixed-diffusion are also important when considering the total diffusive effects. In this study, a two-dimensional Fokker Planck equation is solved numerically using the Alternating Direction Implicit method. Mixed diffusion due to whistler-mode chorus waves tends to slow down the total diffusion in the energy-pitch angle space, particularly at smaller equatorial pitch angles. We then incorporate the electron energy and pitch angle mixed diffusions due to whistler-model chorus waves into the 4-dimensional Radiation Belt Environment (RBE) model and study the effect of mixed diffusion during a storm in October 2002. The 4-D simulation results show that energy and pitch angle mixed diffusion decrease the electron fluxes in the outer belt while electron fluxes in the slot region are enhanced (up to a factor of 2) during storm time.

Zheng, Qiuhua; Fok, Mei-Ching; Albert, Jay; Horne, Richard B.; Meredith, Nigel P.

2011-05-01

57

An Optimum Slope Angle for Solar Collector Systems in Kerman Using a New Model for Diffuse Solar Radiation  

Microsoft Academic Search

In the present article, the monthly average daily diffuse solar radiation on a horizontal surface is calculated first, using 12 new hybrid models. A standard isotropic model is then used to estimate the global solar radiation on inclined surfaces. Finally, the monthly, seasonal, and yearly optimum slope angles to gain the maximum global solar radiation are suggested. The monthly optimum

S. Jafari; E. Jahanshahi Javaran

2012-01-01

58

Terahertz radiation from InAs induced by carrier diffusion and drift  

SciTech Connect

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

Liu, Kai; Xu, Jingzhou; Yuan, Tao; Zhang, X.-C. [Center for THz Research, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States)

2006-04-15

59

Diffusion control in radiation graft polymerization with varying dependence of rate on monomer concentration  

Microsoft Academic Search

The quantitative effect of diffusion control on the rate of radiation-initiated graft polymerization has been studied theoretically for systems in which the diffusion-free reaction may show various dependencies of rate on monomer concentration other than the usual first-order dependence. The study is also very general in that it can be applied to systems involving a variety of different modes of

Kaya Imre; George Odian; Abdelgewad Rabie

1976-01-01

60

Analytical developments in the Wong-Fung-Tam-Gao radiation model of thermal diffusivity  

NASA Astrophysics Data System (ADS)

When the thermal diffusivity, ?, of a thin film on a substrate is measured by means of the mirage method, the photothermal deflection of the probe beam is determined by the heat radiation field contributed by the film and the substrate, heated by the pump beam. A two-dimensional algorithm is here presented in order to deduce the measure of the diffusivities of the film and the substrate in one set of mirage detection from the experimental data.

Lucia, U.; Maino, G.

2004-01-01

61

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.

62

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

63

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

64

Investigation of Boundary and Volume Diffusion by the Method of Beta-Radiation Absorption.  

National Technical Information Service (NTIS)

The diffusion of radioactive iron in iron and iron-3% Si alloys in the temperature range 700 to 890C is reported. An apparatus and technique is described and is based on absorption of the emitted Beta-radiation. Relative contributions of the grain boundar...

V. T. Borisov V. M. Golikov G. V. Shcherbedinskii

1979-01-01

65

Moisture Diffusivity Characteristics of Rough Rice Under Infrared Radiation Heating  

Technology Transfer Automated Retrieval System (TEKTRAN)

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

66

Radiation Biochemistry.  

National Technical Information Service (NTIS)

Contents: physical characteristics of ionizing radiation and its interaction with matter; effect of ionizing radiation on water; formation of peroxides by ionizing radiation; effects of ionizing radiation on simple proteins and their decomposi tion produc...

A. M. Kuzin

1964-01-01

67

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. Along with ...

68

Radiation Therapy  

MedlinePLUS

... how to cope with side effects. What Is Radiation Therapy? Cancer is a disease that causes cells ... when they're giving radiation treatments. How Is Radiation Given? Doctors can give people with cancer radiation ...

69

Radiation Therapy  

MedlinePLUS

... person can start feeling well again. How Is Radiation Given? Cancer can be treated with radiation therapy ... of cancer kids get. Continue What Happens During Radiation Therapy? Because the radiation treatment needs to be ...

70

Radiation dosimetry  

Microsoft Academic Search

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

1991-01-01

71

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

72

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

NASA Astrophysics Data System (ADS)

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

Tu, Weichao

73

Beyond Flux-limited Diffusion: Parallel Algorithms for Multidimensional Radiation Hydrodynamics  

NASA Astrophysics Data System (ADS)

This paper presents a new code for performing multidimensional radiation hydrodynamic (RHD) simulations on parallel computers involving anisotropic radiation fields and nonequilibrium effects. The radiation evolution modules described here encapsulate the physics provided by the serial algorithm of Stone et al. but add new functionality both with regard to physics and numerics. In detailing our method, we have documented both the analytic and discrete forms of the radiation moment solution and the variable tensor Eddington factor (VTEF) closure term. We have described three different methods for computing a short-characteristic formal solution to the transfer equation, from which our VTEF closure term is derived. Two of these techniques include time dependence, a primary physics enhancement of the method not present in the Stone algorithm. An additional physics modification is the adoption of a matter-radiation coupling scheme which is particularly robust for nonequilibrium problems and which also reduces the operations cost of our radiation moment solution. Two key numerical components of our implementation are highlighted: the biconjugate gradient linear system solver, written for general use on massively parallel computers, and our techniques for parallelizing both the radiation moment solution and the transfer solution. Additionally, we present a suite of test problems with a much broader scope than that covered in the Stone work; new tests include nonequilibrium Marshak waves, two-dimensional ``shadow'' tests showing the one-sided illumination of an opaque cloud, and full RHD+VTEF calculations of radiating shocks. We use the results of these tests to assess the virtues and vices of the method as currently implemented, and we identify a key area in which the method may be improved. We conclude that radiation moment solutions closed with variable tensor Eddington factors show a qualitative improvement over results obtained with flux-limited diffusion, and further that this approach has a bright future in the context of parallel RHD simulations in astrophysics.

Hayes, John C.; Norman, Michael L.

2003-07-01

74

Professions in Radiation Therapy  

MedlinePLUS

Professions in: Radiation Therapy Radiation Oncologist Medical Radiation Physicist Radiation Therapist Dosimetrist Radiation Oncology Nurse Social Worker Dietitian Radiation Oncologist Radiation oncologists ...

75

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

76

A review of radiation enhanced diffusion in perspective materials  

Microsoft Academic Search

In this paper, lattice defects and vacancy diffusion coefficients for a variety of materials and temperatures have been calculated on the basis of a modified procedure in [V.A. Starostin, Phys. Chem. Mater. Treat. 5 (1999) 104 (in Russian)] of the model of Beloshitsky [V.V. Beloshitsky, Rad. Eff. 88 (1986) 249]. Arrhenius low enthalpies were defined as linear functions from the

V. A. Starostin

2006-01-01

77

Application of Gamma-Ray Diffusion Theory to Radiation Dosimetry.  

National Technical Information Service (NTIS)

The diffusion equation governing gamma-ray transport has been evaluated in this study by means of random sampling and records of photon trajectories in tissue-like materials obtained for photon sources ranging in energy from 20 to 2750 keV. The records of...

W. H. Ellett

1969-01-01

78

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

PubMed

The purpose of this study is to evaluate repeatability coefficients of diffusion tensor indices to assess whether longitudinal changes in diffusion indices were true changes beyond the uncertainty for individual patients undergoing radiation therapy (RT). Twenty-two patients who had low-grade or benign tumors and were treated by partial brain radiation therapy (PBRT) participated in an IRB-approved MRI protocol. The diffusion tensor images in the patients were acquired pre-RT, week 3 during RT, at the end of RT, and 1, 6, and 18 months after RT. As a measure of uncertainty, repeatability coefficients (RC) of diffusion indices in the segmented cingulum, corpus callosum, and fornix were estimated by using test-retest diffusion tensor datasets from the National Biomedical Imaging Archive (NBIA) database. The upper and lower limits of the 95% confidence interval of the estimated RC from the test and retest data were used to evaluate whether the longitudinal percentage changes in diffusion indices in the segmented structures in the individual patients were beyond the uncertainty and thus could be considered as true radiation-induced changes. Diffusion indices in different white matter structures showed different uncertainty ranges. The estimated RC for fractional anisotropy (FA) ranged from 5.3% to 9.6%, for mean diffusivity (MD) from 2.2% to 6.8%, for axial diffusivity (AD) from 2.4% to 5.5%, and for radial diffusivity (RD) from 2.9% to 9.7%. Overall, 23% of the patients treated by RT had FA changes, 44% had MD changes, 50% had AD changes, and 50% had RD changes beyond the uncertainty ranges. In the fornix, 85.7% and 100% of the patients showed changes beyond the uncertainty range at 6 and 18 months after RT, demonstrating that radiation has a pronounced late effect on the fornix compared to other segmented structures. It is critical to determine reliability of a change observed in an individual patient for clinical decision making. Assessments of the repeatability and confidence interval of diffusion tensor measurements in white matter structures allow us to determine the true longitudinal change in individual patients. PMID:23732399

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

2013-06-04

79

A review of radiation enhanced diffusion in perspective materials  

NASA Astrophysics Data System (ADS)

In this paper, lattice defects and vacancy diffusion coefficients for a variety of materials and temperatures have been calculated on the basis of a modified procedure in [V.A. Starostin, Phys. Chem. Mater. Treat. 5 (1999) 104 (in Russian)] of the model of Beloshitsky [V.V. Beloshitsky, Rad. Eff. 88 (1986) 249]. Arrhenius low enthalpies were defined as linear functions from the temperature for metals, insulators and semiconductors. The anomalous behavior of high temperature superconductors is discussed.

Starostin, V. A.

2006-01-01

80

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

81

Influence of diffusion on photoinduced electron transfer. [laser radiation  

SciTech Connect

Electron transfer from an optically excited donor (rubrene) to randomly distributed acceptors (duroquinone) has been investigated experimentally. The forward electron-transfer process under the influence of diffusion in liquid solution (diethyl sebacate) is compared with that in solid solution (sucrose octaacetate). Steady-state fluorescence yield and time-resolved fluorescence measurements were used to measure the excited-state population of the donor (rubrene). The parameters were used to analyze the electron-transfer dynamics under a variety of acceptor concentrations. The agreement between theoretical predictions and experiments is very good. The forward transfer parameters (a{sub f} and R{sub 0}) in liquid solution are almost identical with those obtained in solid solution.

Song, L.; Dorfman, R.C.; Swallen, S.F.; Fayer, M.D. (Stanford Univ., CA (United States))

1991-05-02

82

Radiation preparation and diffusion behavior of thermally reversible hydrogels  

NASA Astrophysics Data System (ADS)

Temperature sensitive PolyNIPAAm hydrogels in the form of rod were prepared from the binary system of NIPAAm/water and ternary system of NIPAAm/Bis/water by ?-irradiation with 60Co source at room temperature, respectively. The prepared hydrogels had obvious temperature sensitivity (LCST is about 35.0 °C) and suitable mechanical properties. The incorporation of cross-linking agent, N, N'-methylene-bisacrylamide (Bis), into the binary system of monomer/water reduced the gelation dose. The maximum swelling ratio of hydrogels was decreased with the increasing of dose or the incorporation of Bis. The diffusion behavior of water in hydrogels obtained in this work was investigated. In addition, the drug delivery of fluoro uracili (Fu-5) from the hydrogels was investigated.

Zhai, Maolin; Yi, Min; Shu, Jian; Wei, Jinshan; Ha, Hongfei

1998-06-01

83

Impact of horizontal diffusion, radiation and cloudiness parameterization schemes on fog forecasting in valleys  

NASA Astrophysics Data System (ADS)

Fog and low stratus forecasting experiments have been carried out with the numerical weather prediction model ALADIN on a case of long lasting fog. The model has been used with different radiation, cloud diagnosing and horizontal diffusion schemes, different representation of orography, increased vertical resolution and with or without prognostic condensates and turbulent kinetic energy (TKE). Some of the numerical set-ups are able to reproduce the fog (low stratus) field as seen in the satellite images as well as the measured 2m temperature and relative humidity diurnal cycles. The results show that cloud diagnosing schemes and overlap assumptions play a more important role than a more sophisticated radiation scheme, or introduction of prognostic cloud water, ice, rain, snow or TKE. More realistic orography representation and a more physical horizontal diffusion scheme significantly improve the modelled low stratus and 2m temperature in the areas with variable orography.

Tudor, Martina

2010-09-01

84

Radiation heat transfer coefficients for a random void-solid medium with diffusely reflecting surfaces  

SciTech Connect

Radiant heat transport through the void spaces of a gas-solid system is generally important at higher temperatures, such as those encountered in catalytic dehydrogenation reactions or in cracking catalyst regeneration operations. Because of the difficulty of dealing with radiation within the complex bed geometry, the long range effects of scattering from particle to particle through the voids of the bed have not yet been included in any theory of radiation transport in porous solids. A variational principle has been formulated for the radiative and conductive heat transport through a thick random porous bed of void fraction and average pore diameter. The solid material is opaque with thermal conductivity, the gray pore wall surfaces are characterized by an emissivity {epsilon}, with diffusive scattering of all orders in (1-{epsilon}). A void radiation conductivity has been calculated for a model pore structure generated by randomly placed, freely overlapping solid spheres, all of the same radius. This conductivity is compared with corresponding results from kinetic theory, radiation heat transport, and experiments.

Tseng, J.W.C.; Wolf, J.R.; Strieder, W. (Notre Dame Univ., IN (USA). Dept. of Chemical Engineering)

1988-01-01

85

Effects of the Diffuse Ionizing Radiation on the Structure of HII Regions  

Microsoft Academic Search

Problems of the diffuse radiation(DFR) transfer is solved exactly for pure hydrogen nebulae of uniform density, and accuracies of on-the-spot(OTS) approximation are critically examined. For different values of density and spectral types of the central star, we have calculated the degree of ionization and the kinematic temperature of electrons as functions of distance from the central star, and compared them

S. S. Hong; H. I. Sung

1989-01-01

86

Global, direct and diffuse solar radiation on horizontal and tilted surfaces in Jeddah, Saudi Arabia  

Microsoft Academic Search

The measured data of global and diffuse solar radiation on a horizontal surface, the number of bright sunshine hours, mean daily ambient temperature, maximum and minimum ambient temperatures, relative humidity and amount of cloud cover for Jeddah (lat. 21°42?37??N, long. 39°11?12??E), Saudi Arabia, during the period (1996–2007) are analyzed. The monthly averages of daily values for these meteorological variables have

A. A. El-Sebaii; F. S. Al-Hazmi; A. A. Al-Ghamdi; S. J. Yaghmour

2010-01-01

87

NMR measurements of diffusion in concentrated samples: avoiding problems with radiation damping.  

PubMed

Pulsed field gradient spin echo NMR is generally the method of choice for diffusion measurements on liquid samples. With modern high field instruments, however, severe problems can arise when it is applied to samples with very high proton concentrations because of the presence of radiation damping. The problems may be greatly reduced by a suitable choice of experimental parameters, in particular the use of modified stimulated echo pulse sequences with a reduced flip angle for the first pulse. PMID:15214418

Connell, Mark A; Davis, Adrain L; Kenwright, Alan M; Morris, Gareth A

2004-03-01

88

Derivation and solution of multifrequency radiation diffusion equations for homogeneous refractive lossy media  

NASA Astrophysics Data System (ADS)

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 radiation equations are coupled to a diffusion equation for the matter temperature. We are interested in modeling heating and cooling of silica (SiO2), at possibly rapid rates. Hence, in contrast to related work, we retain the temporal derivative of the radiation field. We derive boundary conditions at a planar air-silica interface taking account of reflectivities obtained from the Fresnel relations that include absorption. 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 CO2 laser, ? = 10.59 ?m. In 2D, a laser beam (Gaussian profile, r0 = 0.5 mm for 1/e decay) shines on a disk (radius = 0.4, thickness = 0.4 cm).

Shestakov, A. I.; Vignes, R. M.; Stölken, J. S.

2011-02-01

89

Diffusion of ofloxacin in the endocarditis vegetation assessed with synchrotron radiation UV fluorescence microspectroscopy.  

PubMed

The diffusion of antibiotics in endocarditis vegetation bacterial masses has not been described, although it may influence the efficacy of antibiotic therapy in endocarditis. The objective of this work was to assess the diffusion of ofloxacin in experimental endocarditis vegetation bacterial masses using synchrotron-radiation UV fluorescence microspectroscopy. Streptococcal endocarditis was induced in 5 rabbits. Three animals received an unique i.v. injection of 150 mg/kg ofloxacin, and 2 control rabbits were left untreated. Two fluorescence microscopes were coupled to a synchrotron beam for excitation at 275 nm. A spectral microscope collected fluorescence spectra between 285 and 550 nm. A second, full field microscope was used with bandpass filters at 510-560 nm. Spectra of ofloxacin-treated vegetations presented higher fluorescence between 390 and 540 nm than control. Full field imaging showed that ofloxacin increased fluorescence between 510 and 560 nm. Ofloxacin diffused into vegetation bacterial masses, although it accumulated in their immediate neighborhood. Fluorescence images additionally suggested an ofloxacin concentration gradient between the vegetation peripheral and central areas. In conclusion, ofloxacin diffuses into vegetation bacterial masses, but it accumulates in their immediate neighborhood. Synchrotron radiation UV fluorescence microscopy is a new tool for assessment of antibiotic diffusion in the endocarditis vegetation bacterial masses. PMID:21559378

Batard, Eric; Jamme, Fréderic; Villette, Sandrine; Jacqueline, Cédric; de la Cochetière, Marie-France; Caillon, Jocelyne; Réfrégiers, Matthieu

2011-04-29

90

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, ...

91

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, ...

92

UV Radiation  

MedlinePLUS

... you see, infrared radiation that you feel as heat, and ultraviolet (UV) radiation that you can’t see or feel. UV radiation has a shorter wavelength and higher energy than visible light. It affects human health both ...

93

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

94

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

95

Magnetic Micro-turbulence: Relation of Electron Diffusion to Their Emitted Radiation Spectra  

NASA Astrophysics Data System (ADS)

Kinetic (e.g., Weibel-type) instabilities are ubiquitous in astrophysical high-energy density environments, e.g., in relativistic collisionless shocks and reconnection of strong magnetic fields in neutron star and magnetar magnetospheres, as well as in laboratory laser-produced plasmas. Such instabilities generate strong (sub-equibartition) magnetic fields which reside at small, sub-Larmor scales. Efficient electron acceleration to relativistic energies is not uncommon in such environments. Radiation emitted by these electrons in such fields, called the jitter radiation, exhibits spectra different from what is predicted by synchrotron theory. The small-scale fields also simultaneously affect the particle transport via pitch-angle diffusion. Both effects are interrelated and can be used to diagnose the astrophysical plasmas. Indeed, the radiation pattern is intimately related to the particle orbits and, thus, to the transport properties of the turbulence. We study such a relation between transport in and radiation from micro-scale turbulence via numerical simulations and analysis. We will present the results for both the relativistic and non-relativistic regimes -- the former being important in astrophysical environments and the latter is of great importance to lab experiments.

Medvedev, Mikhail; Keenan, B.

2013-04-01

96

MHD and Thermal Radiation Effects on Exponentially Accelerated Isothermal Vertical Plate with Uniform Mass Diffusion  

NASA Astrophysics Data System (ADS)

Thermal radiation effects on an unsteady free convective flow of a viscous incompressible flow of a past an exponentially accelerated infinite isothermal vertical plate with uniform mass diffusion in the presence magnetic field are considered. The fluid considered here is a gray, absorbing-emitting radiation but a non-scattering medium. The plate temperature is raised to Tw and the concentration level near the plate is also raised to C?w . An exact solution to the dimensionless governing equations is obtained by the Laplace transform method, when the plate is exponentially accelerated with a velocity u= u0 exp(a?t?) in its own plane against gravitational field. The effects of velocity, temperature and concentration fields are studied for different physical parameters such as the magnetic field parameter, thermal radiation parameter, Schmidt number, thermal Grashof number, mass Grashof number and time. It is observed that the velocity increases with decreasing magnetic field parameter or radiation parameter. But the trend is just reversed with respect to a or t .

Muthucumaraswamy, R.; Visalakshi, V.

2013-06-01

97

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

98

Enhanced diffusion of solute metals forming complexes with radiation defects in silica  

NASA Astrophysics Data System (ADS)

The mixing kinetics of Cu, Ag, W, Pt, and Au single layers embedded in silica when irradiated with heavy ions at temperatures (T) of 110 and 300K was investigated by means of in situ RBS analyses in alternation with irradiations. The spreading of peaks related to the metallic species is generally anisotropic and obeys either a quadratic or a linear dependence on the ion dose according to the increasing T. The quadratic law is attributed to a control of the diffusion by the coupling of the large impurity atoms M with matrix defects, and a classical regime of radiation enhanced diffusion is observed when this coupling is made easier (higher T or mass of M). Other factors such as internal stresses affect the rates of M dissolution and diffusion.

Pivin, J. C.; Garrido, E.; Rizza, G.; Thome, L.

1998-05-01

99

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.

100

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

101

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

102

Radiation Enterocolitis  

Microsoft Academic Search

\\u000a This chapter is focused on review of the diagnostic tests and management of radiation enterocolitis. Radiation enterocolitis\\u000a can occur after radiation therapy for urological, gynecological, and gastrointestinal cancer. Diarrhea, which is often a dominant\\u000a symptom, can develop from a few weeks to many years after radiation treatment depending on the severity and the extent of\\u000a the injury. Radiation enterocolitis can

Einar G. Lurix; Jorge A. Zapatier; Andrew Ukleja

103

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

PubMed

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

2012-01-04

104

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

105

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.

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

2012-01-01

106

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

PubMed

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. PMID:11540163

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

1997-02-01

107

The diffuse-global correlation: Its application to estimating solar radiation on tilted surfaces in Marrakesh, Morocco  

Microsoft Academic Search

This investigation has two main objectives. The first is to develop a diffuse-global correlation using data available in Marrakesh for diffuse component calculation purposes. The second objective is to carry out a statistical comparison of three specific models for estimating daily global radiation on tilted surfaces and to recommend the most accurate for the Marrakesh location. The isotropic model and

A. J. Wilkinson

1996-01-01

108

Distinction between postoperative recurrent glioma and radiation injury using MR diffusion tensor imaging  

Microsoft Academic Search

Introduction  This study aims to evaluate the differentiated effectiveness of MR diffusion tensor imaging (DTI) to postoperative recurrent\\u000a glioma and radiation injury.\\u000a \\u000a \\u000a \\u000a \\u000a Methods  Conventional MRI and DTI examination were performed using Siemens 3.0 T MR System for patients with new contrast-enhancing\\u000a lesions at the site of treated tumor with postoperative radiotherapy. The region of interest was manually drawn on ADC and\\u000a FA maps

Jun-Ling Xu; Yong-Li Li; Jian-Min Lian; She-wei Dou; Feng-Shan Yan; Hui Wu; Da-peng Shi

2010-01-01

109

Radiation-induced early changes in the brain and behavior: serial diffusion tensor imaging and behavioral evaluation after graded doses of radiation.  

PubMed

The nuclear arsenal and the use of nuclear technologies have enhanced the likelihood of whole-body/partial-body radiation exposure. The central nervous system is highly susceptible to even low doses of radiation. With the aim of detecting and monitoring the pathologic changes of radiation-induced damage in brain parenchyma, we used serial diffusion tensor magnetic resonance imaging (DTI) with a 7T magnetic resonance unit and neurobehavioral assessments mice irradiated with 3-, 5-, and 8-Gy doses of radiation. Fractional anisotropy (FA) and mean diffusivity (MD) values at each time point (baseline, day 1, day 5, and day 10) were quantified from hippocampus, thalamus, hypothalamus, cudate-putamen, frontal cortex, sensorimotor cortex, corpus callosum, cingulum, and cerebral peduncle. Behavioral tests were performed at baseline, day 5, and day 10. A decrease in FA values with time was observed in all three groups. At day 10, dose-dependent decreases in FA and MD values were observed in all of the regions compared with baseline. Behavioral data obtained in this study correlate with FA values. Radiation-induced affective disorders were not radiation dose dependent, insofar as the anxiety-like symptoms at the lower dose (3 Gy) mimics to the symptoms with the higher dose (8 Gy) level but not with the moderate dose. However, there was a dose-dependent decline in cognitive function as well as FA values. Behavioral data support the DTI indices, so it is suggested that DTI may be a useful tool for noninvasive monitoring of radiation-induced brain injury. PMID:22605562

Trivedi, Richa; Khan, Ahmad Raza; Rana, Poonam; Haridas, Seenu; Hemanth Kumar, B S; Manda, Kailash; Rathore, Ram K S; Tripathi, Rajendra P; Khushu, Subash

2012-05-17

110

Fabric radiators  

NASA Astrophysics Data System (ADS)

The design of large, high-temperature space radiators is still an evolving discipline. Researchers expanded the data base available to a designer by studying a novel class of radiators constructed of ceramic fabrics and/or composite materials. It appears that fabric radiators have features not available in more conventional radiator types, while offering the light weight and stowability of advanced radiators such as liquid droplet types. Experiments show that fabrics can be treated to become impermeable to the working fluid while retaining flexibility. This feature of fabrics, when allied to their low density, provides a material well-adapted to radiator construction.

Antoniak, Zenen I.; Jacox, Michael G.

111

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

112

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

113

Radiation enhanced diffusion of hydrogen in perovskite-type oxide ceramics under reactor irradiation  

NASA Astrophysics Data System (ADS)

Electrical conductivity of yttrium-doped perovskite-type barium-cerium oxide ceramics (BaCe0.9Y0.1O3-?), implanted with 10 keV H2+ ions, was measured in situ under fission reactor irradiation. An increment of the electrical conductivity, called radiation induced conductivity (RIC), was observed with increasing ionizing dose rate. The RIC for the specimen with implanted H at 1.1 kGy/s and irradiation temperatures 473 673 K was higher by about four orders of magnitude than the base conductivity without radiation at 0 Gy/s, and was about two orders of magnitude higher than that without H. The RIC is attributed to electronic excitation as well as hydrogen enhanced diffusion. The RIC greatly depended on the irradiation temperature, but was insensitive to the fast neutron fluence in the range 3.3 7.4 × 1023 n/m2. The results show that the radiation induced defects, produced by neutron collisions, and radiolysis have no influence on the electronic and protonic conduction.

Tsuchiya, B.; Shikama, T.; Nagata, S.; Toh, K.; Narui, M.; Yamazaki, M.

2007-08-01

114

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.

2007-03-01

115

New self-similar radiation-hydrodynamics solutions in the high-energy density, equilibrium diffusion limit  

NASA Astrophysics Data System (ADS)

This work presents semi-analytic solutions to a radiation-hydrodynamics problem of a radiation source driving an initially cold medium. Our solutions are in the equilibrium diffusion limit, include material motion and allow for radiation-dominated situations where the radiation energy is comparable to (or greater than) the material internal energy density. As such, this work is a generalization of the classical Marshak wave problem that assumes no material motion and that the radiation energy is negligible. Including radiation energy density in the model serves to slow down the wave propagation. The solutions provide insight into the impact of radiation energy and material motion, as well as present a novel verification test for radiation transport packages. As a verification test, the solution exercises the radiation-matter coupling terms and their v/c treatment without needing a hydrodynamics solve. An example comparison between the self-similar solution and a numerical code is given. Tables of the self-similar solutions are also provided.

Lane, Taylor K.; McClarren, Ryan G.

2013-09-01

116

Radiation Monitoring.  

National Technical Information Service (NTIS)

This general discussion of radiation and radioactivity as they relate to mines, particularly uranium mines, includes the following topics: general radiation discussion; radioactive minerals and related health hazards in mining; lung cancer among uranium a...

1979-01-01

117

Radiation Therapy  

MedlinePLUS

... rays, but the power can also come from protons or other types of energy. The term "radiation ... Why it's done Mayo Clinic products and services Proton beam therapy at Mayo Clinic Radiation therapy at ...

118

Radiation Carcinogenesis.  

National Technical Information Service (NTIS)

The risk of iatrogenic tumors with radiation therapy is so outweighed by the benefit of cure that estimates of risk have not been considered necessary. However, with the introduction of chemotherapy, combined therapy, and particle radiation therapy, the c...

R. J. M. Fry

1976-01-01

119

Radiation Cataract  

NASA Astrophysics Data System (ADS)

These studies provide an opportunity to study the effects of low-dose radiation exposure and the influence(s) of genetic radiosensitivity in a rodent model that has great relevance and similarity to human response to radiation exposure and determination of appropriate human exposure guidelines. Futhermore, any extension of the presumed radiation cataract threshold in this animal model to lower doses is likely to be important to the development of appropriate guidelines for national space radiation risk policy.

Kleiman, Norman; Hall, Eric; Brenner, David; Lieberman, Howard; Smilenov, Lubomir

120

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 long time, it raises ...

121

Radiation receiver  

Microsoft Academic Search

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

Hunt; Arlon J

1983-01-01

122

(Radiation protection)  

Microsoft Academic Search

The traveler attended the Seventh Congress of the International Radiation Protection Association (IRPA) in Sydney, Australia, April 11--15, 1988. This conference consisted of a comprehensive technical program with oral and poster presentations in all areas of radiation protection including several topics which were of special interest to the traveler; e.g., neutron dosimetry, personnel dosimetry and instrumentation, radiobiology, and radiation accidents.

Swaja

1988-01-01

123

Diffusive-to-ballistic transition in dynamic light transmission through thin scattering slabs: a radiative transfer approach  

NASA Astrophysics Data System (ADS)

We study the deviation from diffusion theory that occurs in the dynamic transport of light through thin scattering slabs. Solving numerically the time-dependent radiative transfer equation, we obtain the decay time and the effective diffusion coefficient Deff. We observe a nondiffusive behavior for systems whose thickness L is smaller than 8ltr, where ltr is the transport mean free path. We introduce a simple model that yields the position of the transition between the diffusive and the nondiffusive regimes. The size dependence of Deff in the nondiffusive region is strongly affected by internal reflections. We show that the reduction of ~50% of Deff that was observed experimentally [Phys. Rev. Lett. 79, 4369 (1997)] can be reproduced by the radiative transfer approach. We demonstrate that the radiative transfer equation is an appropriate tool for studying dynamic light transport in thin scattering systems when coherent effects play no significant role.

Elaloufi, Rachid; Carminati, Rémi; Greffet, Jean-Jacques

2004-08-01

124

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

125

Large eddy simulations of turbulence-chemistry-radiation interactions in diffusion flames  

NASA Astrophysics Data System (ADS)

The efficiency and pollutant emission characteristics of practical combustion devices often depend critically on interactions between turbulent flow, finite-rate combustion chemistry, and thermal radiation from combustion products and soot. Due to the complex nonlinear coupling of these phenomena, modeling and/or simulation of practical combustors or even laboratory flames undergoing significant extinction and reignition or strong soot formation remain elusive. Methods based on the determination of the probability density function (PDF) of the joint thermochemical scalar variables are one of the most promising approaches for handling turbulence-chemistry-radiation interactions in flames. PDF methods have gained wide acceptance in the context of Reynolds-Averaged Navier-Stokes (RANS) approaches to predicting mean flowfields as evidenced by their availability in commercial CFD codes such as FLUENT(TM). Over the past 6 years, the development and application of the filtered mass density function (FMDF) approach in the context of large eddy simulations (LES) of turbulent flames has gained considerable ground. Some of the key issues remaining to be explored regarding the FMDF approach in LES are related to mixing model and chemical mechanism sensitivities of predicted flame statistics, especially for flames undergoing significant extinction and reignition, and application of the approach to more realistic flames, for example, those involving soot formation and luminous thermal radiation. In this study, we explore the issue of mixing model sensitivity, as well as the role of the presumed constant (independent of chemistry and species) mixing frequency, for several laboratory and idealized piloted turbulent diffusion flames at different Reynolds numbers and hence, different levels of local flame extinction/reignition. The laboratory flames are modeled after the Sandia Turbulent Nonpremixed Flames D, E, and F and are predicted using a RANS/PDF transport model in FLUENT. The idealized flames are simulated using an in-house LES/FMDF code modified to allow different mixing models. In addition, we extend the in-house LES/FMDF code to include luminous thermal radiation from a flamelet soot model, and conduct simulations of idealized strongly radiating turbulent flames. A new parallel radiation solver, employing the discrete ordinates method (DOM), is developed and tested as part of this effort. Our findings from both studies confirm that the level of local extinction/reignition predicted in the flame is sensitive to the choice of mixing model and the mixing frequency and suggest the use of a variable mixing frequency could improve the models. Also, our idealized strongly radiating flame studies demonstrate the utility of the LES/FMDF approach for such flames, highlight the importance of turbulence-radiation interactions, and pave the way for the inclusion of finite-rate soot transport and kinetics models and quantitative prediction of laboratory scale sooting flames in the future.

Chandy, Abhilash J.

126

Radiation Protection  

NASA Astrophysics Data System (ADS)

Radiation protection is a very important aspect for the application of particle detectors in many different fields, like high energy physics, medicine, materials science, oil and mineral exploration, and arts, to name a few. The knowledge of radiation units, the experience with shielding, and information on biological effects of radiation are vital for scientists handling radioactive sources or operating accelerators or X-ray equipment. This article describes the modern radiation units and their conversions to older units which are still in use in many countries. Typical radiation sources and detectors used in the field of radiation protection are presented. The legal regulations in nearly all countries follow closely the recommendations of the International Commission on Radiological Protection (ICRP). Tables and diagrams with relevant information on the handling of radiation sources provide useful data for the researcher working in this field.

Grupen, Claus

127

Atoms, radiation, and radiation protection  

Microsoft Academic Search

This book describes basic atomic and nuclear structure, the physical processes that result in the emission of ionizing radiations, and external and internal radiation protection criteria, standards, and practices from the standpoint of their underlying physical and biological basis. The sources and properties of ionizing radiation-charged particles, photons, and neutrons-and their interactions with matter are discussed in detail. The underlying

1986-01-01

128

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

129

On the Momentum Diffusion of Radiating Ultrarelativistic Electrons in a Turbulent Magnetic Field  

NASA Astrophysics Data System (ADS)

Here we investigate some aspects of stochastic acceleration of ultrarelativistic electrons by magnetic turbulence. In particular, we discuss the steady state energy spectra of particles undergoing momentum diffusion due to resonant interactions with turbulent MHD modes, taking rigorously into account direct energy losses connected with different radiative cooling processes. For the magnetic turbulence we assume a given power spectrum of the type W(k)~k-q. In contrast to the previous approaches, however, we assume a finite range of turbulent wavevectors k, consider a variety of turbulence spectral indices 1<=q<=2, and concentrate on the case of a very inefficient particle escape from the acceleration site. We find that for different cooling and injection conditions, stochastic acceleration processes tend to establish a modified ultrarelativistic Maxwellian distribution of radiating particles, with the high-energy exponential cutoff shaped by the interplay between cooling and acceleration rates. For example, if the timescale for the dominant radiative process scales with the electron momentum as ~pr, the resulting electron energy distribution is of the form ne(p)~p2exp[-(1/a)(p/peq)a], where a=2-q-r and peq is the equilibrium momentum defined by the balance between the stochastic acceleration and energy loss timescales. We also discuss in more detail the synchrotron and inverse-Compton emission spectra produced by such an electron energy distribution, taking into account Klein-Nishina effects. We point out that the curvature of the high-frequency segments of these spectra, even though they are produced by the same population of electrons, may be substantially different between the synchrotron and inverse-Compton components.

Stawarz, ?ukasz; Petrosian, Vahe

2008-07-01

130

He diffusion in zircon: Observations from (U-Th)/He age suites and 4He diffusion experiments and implications for radiation damage and anisotropic effects  

NASA Astrophysics Data System (ADS)

Despite widespread use of zircon (U-Th)/He thermochronometry in many geologic applications, our understanding of the kinetics of He diffusion in this system is rudimentary. Previous studies have shown that both radiation damage and crystallographic anisotropy may strongly influence diffusion kinetics and ages. We present observations of zircon He ages from multiple single-grain analyses from both detrital and bedrock suites from a wide variety of locations, showing relationships consistent with effects arising from the interaction of radiation damage and anisotropy. Individual zircons in each suite have experienced the same post-depositional or exhumational t-T history but grains appear to have experienced differential He loss that is correlated with effective uranium (eU) content, a proxy for the relative extent of radiation damage within each suite. Several suites of zircons heated to partial resetting upon burial or that have experienced slow cooling show positive correlations between age and eU. Examples of partially reset detrital samples include Cretaceous Sevier foreland basin sandstones buried to ~6-8 km depth, with ages ranging from 88-309 Ma across an eU range of 215-1453 ppm, and Apennines and Olympics greywackes heated to >~120 °C, showing similar trends. Some slowly-cooled bedrock samples also show positive age-eU correlations, suggesting increasing closure temperature with higher extents of radiation damage. Conversely, zircons from cratonal bedrock samples with high levels of radiation damage—measured as accumulated alpha dosage (in this case >~10^18 ?/g)—generally show negative age-eU correlations. We interpret these contrasting age-eU relationships as a manifestation of the interaction of radiation damage and anisotropic diffusion: at low damage, He diffusivity is relatively high and preferentially through c-axis-parallel channels. As suggested by Farley (2007), however, with increasing damage, channels are progressively blocked and He diffusivity decreases. Eventually, a crystal reaches a threshold level (>~10^18 ?/g ) wherein radiation damage is so extensive that damage zones become interconnected and He diffusivity increases once again. In order to evaluate these assertions, we conducted a series of step-heating experiments on several pairs of zircon slabs. Individual slabs were crystallographically oriented either orthogonal or parallel to the c-axis and each pair possessed varying degrees of radiation damage. Results from these experiments provide new closure temperature estimates, explain age-eU correlations within a data set, and allow us to construct diffusion models that more accurately describe the t-T history of a given sample.

Guenthner, W. R.; Reiners, P. W.

2009-12-01

131

Radiation therapy improves treatment outcome in patients with diffuse large B-cell lymphoma.  

PubMed

The effects of radiotherapy (RT) after chemotherapy in patients with diffuse large B-cell lymphoma (DLBCL) remain unclear; several trials have yielded conflicting results. This study examined the effect of RT after cyclophosphamide, doxorubicin, vincristine, and prednisone + rituximab (R-CHOP) treatment on event-free (EFS) and overall (OS) survival. Data from 216 patients with DLBCL who were enrolled in two clinical trials at Italian Lymphoma Study Group sites and were subjected to six R-CHOP cycles and involved-field radiotherapy (IFRT) were retrospectively analyzed. IFRT treatment yielded significant EFS benefit, with a 66% reduction in the risk of death and/or disease progression. Cox analysis, when adjusted for age, gender, stage, performance status (PS), lactate dehydrogenase (LDH), and disease bulk, confirmed the significant EFS benefit of IFRT. The role of RT in DLBCL in the rituximab era is unclear. Future studies must take into account new radiation techniques and the response to chemotherapy based on functional imaging. Prospective randomized trials incorporating response-adapted therapy and modern radiation techniques are needed. PMID:21663499

Marcheselli, Luigi; Marcheselli, Raffaella; Bari, Alessia; Liardo, Eliana Valentina; Morabito, Fortunato; Baldini, Luca; Brugiatelli, Maura; Merli, Francesco; Di Renzo, Nicola; Sacchi, Stefano

2011-06-12

132

Laminar Smoke Point Based Subgrid Soot Radiation Modeling Applied to LES of Buoyant Turbulent Diffusion Flames  

NASA Astrophysics Data System (ADS)

Large eddy simulations (LES) of gaseous buoyant turbulent flames have been conducted with the application of a flamelet based soot-radiation model. The subgrid model applies a turbulent eddy description of soot formation, oxidation and radiation and is based on the laminar smoke point concept. Two parameters, a local turbulent strain rate and prior enthalpy loss/gain fraction influence the soot formation and radiation. Radiation heat transfer is simulated by solving the finite volume discretized form of the radiative transfer equation (RTE) with the subgrid soot-radiation model implemented. The radiant heating of surfaces in close proximity of the flames is computed and predicted heat fluxes and surface temperatures are compared against experimental data. Fire growth in a rack storage arrangement is simulated with the application of a pyrolysis model. Computed heat release rate (HRR) is compared against experimental data.

Chatterjee, Prateep; de Ris, John L.; Wang, Yi; Krishnamoorthy, Niveditha; Dorofeev, Sergey B.

2012-06-01

133

Solar radiation statistics for Iran  

Microsoft Academic Search

Various prediction methods for calculating the mean monthly solar radiation parameters are examined. A suitable method is proposed for predicting the mean monthly values of direct, diffuse, and total solar radiation at different locations in Iran. This method is based on the assumption that the direct and diffuse components of solar radiation are primarily functions of solar zenith angle and

M DANESHYAR

1978-01-01

134

Diffusion-Weighted Imaging in the Follow-up of Treated High-Grade Gliomas: Tumor Recurrence versus Radiation Injury  

Microsoft Academic Search

BACKGROUND AND PURPOSE: Diffusion-weighted (DW) MR imaging is a means to char- acterize and differentiate morphologic features, including edema, necrosis, and tumor tissue, by measuring differences in apparent diffusion coefficient (ADC). We hypothesized that DW imaging has the potential to differentiate recurrent or progressive tumor growth from treat- ment-induced damage to brain parenchyma in high-grade gliomas after radiation therapy. METHODS:

Patrick A. Hein; Clifford J. Eskey; Jeffrey F. Dunn; Eugen B. Hug

135

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

NASA Astrophysics Data System (ADS)

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

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

2013-10-01

136

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

Microsoft Academic Search

Quantifying radial transport of radiation belt electrons in ULF wave fields is essential for understanding the variability of the trapped relativistic electrons. To estimate the radial diffusion coefficients (DLL), we follow MeV electrons in realistic magnetospheric configurations and wave fields calculated from a global MHD code. We create idealized pressure-driven MHD simulations for controlled solar wind velocities (hereafter referred to

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

2010-01-01

137

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

138

Hawking radiation  

NASA Astrophysics Data System (ADS)

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

Parentani, Renaud; Spindel, Philippe

2011-12-01

139

Radiation protection.  

PubMed

One of radiologic technologists' most important professional obligations is protecting patients, other members of the health care team, the public and themselves from as much radiation-related harm as possible while also maximizing the screening, diagnostic and therapeutic potential of ionizing radiation. This article reviews the different types of radiation dose and how radiation affects the body. Patient shielding, personnel dosimeters and area monitors are discussed, along with beam collimation and filtration. The author also describes protocols to protect pregnant patients and pregnant technologists. PMID:17519374

Brusin, Joyce Helena

140

Parametric validations of analytical lifetime estimates for radiation belt electron diffusion by whistler waves  

NASA Astrophysics Data System (ADS)

The lifetimes of electrons trapped in Earth's radiation belts can be calculated from quasi-linear pitch-angle diffusion by whistler-mode waves, provided that their frequency spectrum is broad enough and/or their average amplitude is not too large. Extensive comparisons between improved analytical lifetime estimates and full numerical calculations have been performed in a broad parameter range representative of a large part of the magnetosphere from L ~ 2 to 6. The effects of observed very oblique whistler waves are taken into account in both numerical and analytical calculations. Analytical lifetimes (and pitch-angle diffusion coefficients) are found to be in good agreement with full numerical calculations based on CRRES and Cluster hiss and lightning-generated wave measurements inside the plasmasphere and Cluster lower-band chorus waves measurements in the outer belt for electron energies ranging from 100 keV to 5 MeV. Comparisons with lifetimes recently obtained from electron flux measurements on SAMPEX, SCATHA, SAC-C and DEMETER also show reasonable agreement.

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

2013-04-01

141

Cooling following large volcanic eruptions corrected for the effect of diffuse radiation on tree rings  

NASA Astrophysics Data System (ADS)

The lack of a larger cooling in proxy records of climate change following large volcanic eruptions such as those of Tambora in 1815 and Krakatau in 1883 has long been a puzzle for climatologists. These records, however, may have been biased by enhanced tree growth for several years following each eruption induced by additional diffuse radiation caused by the stratospheric volcanic aerosol clouds from the eruptions. By comparing proxy reconstructions of climate with and without tree ring data, this effect is demonstrated for the five largest eruptions for the period 1750-1980. When proxy records of Northern Hemisphere climate change are corrected for this proposed diffuse effect, there is no impact on climate change for time scales longer than 20 years. However, it now appears that there was a hemispheric cooling of about 0.6°C for a decade following the unknown volcanic eruption of 1809 and Tambora in 1815, and a cooling of 0.3°C for several years following the Krakatau eruption of 1883.

Robock, Alan

2005-03-01

142

A coupling model of light propagation based on the radiative transfer and diffusion equations  

NASA Astrophysics Data System (ADS)

Recently, transport phenomena of photon energy have been attractive topics due to the applications of the biomedical imaging such as diffuse optical tomography (DOT). For improvement of numerical modeling in DOT, accurate and fast calculations of light propagations in biological tissues are necessary. This paper proposes a light propagation model based on the radiative transfer and diffusion equations (RTE and DE) in random media. Numerical calculations of light propagation using the both equations provide the condition for the DE to be valid. Length and time scales for the validity of the DE are estimated to be about 10lm and 20lm/?, respectively, where lm is the mean free path of photon and v is the light velocity. The proposed model can provide accurate descriptions of spatial and temporal profiles of light propagation in random media subject to the refractive-index mismatched boundary condition. Also, it can appropriately reduce computation time by an order of magnitude when compared with that fully computing the RTE.

Fujii, Hiroyuki; Hoshi, Yoko; Okawa, Shinpei; Yoshinaga, Tetsuya; Kohno, Satoru; Yamada, Yukio

2013-10-01

143

Two-flux and diffusion methods for radiative transfer in composite layers  

Microsoft Academic Search

Temperature distributions and heat fluxes are predicted in composite semitransparent layers heated or cooled on both sides by radiation and convection. Two approximate methods were used for performing spectral calculations, and the results were validated by comparison with `exact ` numerical solutions of the radiative transfer equations. The composite layers have refractive indices larger than one, and isotropic scattering is

C. M. Spuckler; R. Siegel

1996-01-01

144

Spatial and Temporal Distribution of Diffuse and Direct Solar Radiation in the Federal Republic of Germany.  

National Technical Information Service (NTIS)

The amount of incoming solar radiation at different times of the day and the year in different climatic regions was investigated for the planning of solar energy facilities. For most applications, the incident global radiation is to be separated into dire...

F. Kasten K. Dehne H. D. Behr U. Bergholter

1984-01-01

145

Radiation enteritis  

SciTech Connect

Acute radiation enteritis is almost inevitable in the curative treatment of malignant tumors of the abdomen and pelvic area. It is frequently a self-limiting disorder of intestinal function associated with reversible mucosal changes of the intestine. The prevalence of chronic radiation enteritis has been underestimated in most surgical series and the majority of patients with symptoms probably do not seek medical advice until a serious complication occurs. Although associated with specific histologic features, the mechanism of chronic radiation injury is poorly understood. The prevalence, pathogenesis, diagnosis and approaches to the treatment and prevention of acute and chronic radiation enteritis are discussed herein. Recent investigative techniques should lead to a better understanding of the physiopathologic characteristics of radiation enteritis and, thereby, provide a more rational basis for treatment which, at the present time, is unsatisfactory. Attempts to reduce the prevalence of radiation enteritis should be directed toward careful patient selection for radiation treatment of the pelvis and to minimize injury to the small intestine, by reducing the volume of small intestine in the radiation area and providing more individualized dosimetry. 71 references.

Yeoh, E.K.; Horowitz, M.

1987-10-01

146

COSMIC RADIATION  

Microsoft Academic Search

Observations made rn the universe concemrng cosmic radiatron are ; discussed. Cosmic radiation on its way to earth traverses an area which ; influences its rntensity. ln crossing the geomagnetic field part of the cosmic ; radiation is diverted. Intensity depends on latitude and partly on elevation of ; the observatron point. Cosmic radiatron is also influenced by changing air

Svoboda

1960-01-01

147

Hawking Radiation  

NSDL National Science Digital Library

This resource presents explanations and sample calculations of: the event horizon (or Schwarzschild radius) of a black hole mass; the lifetime of virtual photons; the frequency of Hawking radiation; and black hole temperature, luminosity, and lifetime. Background information is provided on the classical law of gravitation, gravitational potential energy, the quantization of energy, black body radiation, and the equivalence of mass and energy.

148

Radiation therapy  

MedlinePLUS

... can also damage or kill healthy cells. The death of healthy cells can lead to side effects. These side effects depend on the dose of radiation, and how often you have the therapy. External beam radiation may cause skin changes, such as hair loss, red or ...

149

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.

150

Radiation dosimetry  

Microsoft Academic Search

This book consists of five papers on the following topics: bioeffect dosimetry in radiation therapy; a comparison of national and international megavoltage calibration protocols; recent advances in electron and photon dosimetry; microdosimetry and its application to biological processes; and ultraviolet radiation dosimetry and measurement.

Orton

1985-01-01

151

RADIATION BALANCE  

Technology Transfer Automated Retrieval System (TEKTRAN)

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

152

Radiation detector  

DOEpatents

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

Fultz, B.T.

1980-12-05

153

Radiation detector  

DOEpatents

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

Fultz, Brent T. (Berkeley, CA)

1983-01-01

154

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

155

A theoretical analysis of the influence of turbulence on radiative emission in turbulent diffusion flames of methane  

NASA Astrophysics Data System (ADS)

A theoretical analysis is reported to quantify the increase of radiative emission due to turbulence for methane diffusion flames burning in air. The instantaneous thermochemical state of the reactive mixture is described by a flamelet model and a detailed chemical mechanism. Mean values of the absorption coefficient, blackbody radiation intensity and radiative emission are evaluated for different turbulence levels by assuming the pdf shape of mixture fraction. The results show that turbulent fluctuations generally contribute to reduce the Planck mean absorption coefficient of the medium, in contrast with the blackbody radiation intensity, which is significantly increased by turbulence. If the turbulence level is relatively small, the influence of turbulence on the absorption coefficient is marginal. Otherwise, fluctuations of the absorption coefficient of the medium should be taken into account. The mean radiative emission is underestimated if turbulent fluctuations are fully ignored and overestimated if only temperature fluctuations are considered, while neglecting fluctuations of the absorption coefficient of the medium, the error being generally higher in the latter case. The effects of turbulence on radiative emission are stronger in the fuel-lean region and close to stoichiometric conditions than in the fuel-rich region.

Coelho, P. J.

2012-06-01

156

Solar radiation on Mars  

SciTech Connect

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

Appelbaum, J.; Flood, D.J.

1989-08-01

157

Solar radiation in Jamaica  

SciTech Connect

Average monthly global radiation in Jamaica was calculated for the years between 1978 and 1987 from values measured at 12 stations and from Angstrom-coefficient derived values. From these values daily global radiation was estimated for various periods at grid points separated by approximately 10 km on a square. Three dimensional plots and contour maps for the various periods were produced. The interpolation was based on kriging adopted by Hay. A relationship between global and diffuse radiation based on the Liu and Jordan relationship was obtained. The errors in the interpolated annual values were less than 10%. The maps were made available to the public with suggested usages of solar energy. Diffuse radiation formed less than 50% of the total radiation.

Chen, A.A.; Chin, P.N.; Forrest, W.; McLean, P. (Univ. of the West Indies, Kingston (Jamaica)); Grey, C. (Meteorological Office, Kingston (Jamaica))

1994-11-01

158

Synchrotron Radiation  

SciTech Connect

This book covers the physical aspects of synchrotron radiation generation and is designed as a textbook and reference for graduate students, teachers and scientists utilizing synchrotron radiation. It is my hope that this text may help especially students and young researchers entering this exciting field to gain insight into the characteristics of synchrotron radiation. Discovered in 1945, synchrotron radiation has become the source of photons from the infrared to hard x-rays for a large community of researchers in basic and applied sciences. This process was particularly supported by the development of electron accelerators for basic research in high energy physics. Specifically, the development of the store ring and associated technologies resulted in the availability of high brightness photon beams far exceeding other sources. In this text, the physics of synchrotron radiation for a variety of magnets is derived from first principles resulting in useful formulas for the practitioner. Since the characteristics and quality of synchrotron radiation are intimately connected with the accelerator and electron beam producing this radiation, a short overview of relevant accelerator physics is included.

Wiedemann, Helmut

2003-08-11

159

Liquid-Phase Diffusion-Controlled Solute Escape from a Droplet Cooled by Vaporization and Radiation.  

National Technical Information Service (NTIS)

Only a fraction of a volatile solute initially present in a droplet can escape prior to ultimate droplet solidification caused by radiative and vaporization cooling. If the droplet size does not appreciably change during the escape process, the authors sh...

D. E. Rosner

1972-01-01

160

Phase II trial of tipifarnib and radiation in children with newly diagnosed diffuse intrinsic pontine gliomas  

PubMed Central

We performed a phase II study to assess the efficacy and toxicity of tipifarnib, a farnesyltransferase inhibitor, administered with radiation therapy (RT) in children with newly diagnosed diffuse intrinsic pontine gliomas. Children 3-21 years old with pontine gliomas (BSGs) were treated with concurrent tipifarnib and RT, followed by adjuvant tipifarnib. Tipifarnib was taken orally twice daily (125 mg/m2/dose) during RT; after RT, it was taken at 200 mg/m2 twice daily for 21 days, in 28-day cycles. Initial and follow-up neuroimaging was centrally reviewed. Forty eligible patients (median age, 5.5 years; range, 3.3–16.5 years) had a median progression-free survival of 6.8 months (range, 0.2-18.6 months) and median overall survival of 8.3 months (range, 0.2-18.6 months). Kaplan–Meier estimates (± standard error) of 1-year progression-free and overall survival were 12.9% ±4.9% and 34.3% ±7.4%, respectively. A single patient remained on tipifarnib without progression at the completion of the study, two years after initiation of treatment. Seven patients were without disease progression for at least six months, three of whom remained controlled for more than a year. The most frequent toxicity was grade 3 lymphopenia. We documented a single instance of “pseudoprogression” by neuroimaging review. We found no discordance among 3 approaches to defining disease progression: as interpreted by treating institutions (based on clinical status and/or imaging) and by central review (using bi-dimensional tumor “area” versus volumetric measurements). For children with diffuse BSGs, tipifarnib administered with irradiation offered no clinical advantage over historical controls. Biopsies and molecular analyses of pediatric BSGs are vital for identification of new agents and for rational use of targeted agents.

Haas-Kogan, Daphne A.; Banerjee, Anuradha; Poussaint, Tina Young; Kocak, Mehmet; Prados, Michael D.; Geyer, J. Russell; Fouladi, Maryam; Broniscer, Alberto; Minturn, Jane E.; Pollack, Ian F.; Packer, Roger J.; Boyett, James M.; Kun, Larry E.

2011-01-01

161

Phase II trial of tipifarnib and radiation in children with newly diagnosed diffuse intrinsic pontine gliomas.  

PubMed

We performed a phase II study to assess the efficacy and toxicity of tipifarnib, a farnesyltransferase inhibitor, administered with radiation therapy (RT) in children with newly diagnosed diffuse intrinsic pontine gliomas. Children 3-21 years old with pontine gliomas (BSGs) were treated with concurrent tipifarnib and RT, followed by adjuvant tipifarnib. Tipifarnib was taken orally twice daily (125 mg/m(2)/dose) during RT; after RT, it was taken at 200 mg/m(2) twice daily for 21 days, in 28-day cycles. Initial and follow-up neuroimaging was centrally reviewed. Forty eligible patients (median age, 5.5 years; range, 3.3-16.5 years) had a median progression-free survival of 6.8 months (range, 0.2-18.6 months) and median overall survival of 8.3 months (range, 0.2-18.6 months). Kaplan-Meier estimates (± standard error) of 1-year progression-free and overall survival were 12.9% ±4.9% and 34.3% ±7.4%, respectively. A single patient remained on tipifarnib without progression at the completion of the study, two years after initiation of treatment. Seven patients were without disease progression for at least six months, three of whom remained controlled for more than a year. The most frequent toxicity was grade 3 lymphopenia. We documented a single instance of "pseudoprogression" by neuroimaging review. We found no discordance among 3 approaches to defining disease progression: as interpreted by treating institutions (based on clinical status and/or imaging) and by central review (using bi-dimensional tumor "area" versus volumetric measurements). For children with diffuse BSGs, tipifarnib administered with irradiation offered no clinical advantage over historical controls. Biopsies and molecular analyses of pediatric BSGs are vital for identification of new agents and for rational use of targeted agents. PMID:21339191

Haas-Kogan, Daphne A; Banerjee, Anuradha; Poussaint, Tina Young; Kocak, Mehmet; Prados, Michael D; Geyer, J Russell; Fouladi, Maryam; Broniscer, Alberto; Minturn, Jane E; Pollack, Ian F; Packer, Roger J; Boyett, James M; Kun, Larry E

2011-03-01

162

Escape Methods Vs Diffusion for Radiation Transport in Z-Pinch Simulations  

Microsoft Academic Search

Summary form only given. In Z-pinch loads designed for X-ray production the imploding kinetic and some of the electromagnetic energy is converted into radiation. Hence radiation and atomic processes control the plasma conditions of such loads at the time of assembly on axis. Simulations of Z-pinch dynamics need to properly account for this microphysics to be a viable analysis tool

J. L. Giuliani; R. W. Clark; J. P. Apruzese; J. W. Thornhill; J. Davis; T. A. Haill; C. Deeney; T. A. Mehlhorn

2005-01-01

163

Radiation-Induced Changes in Normal-Appearing White Matter in Patients With Cerebral Tumors: A Diffusion Tensor Imaging Study  

SciTech Connect

Purpose: To quantify the radiation-induced changes in normal-appearing white matter before, during, and after radiotherapy (RT) in cerebral tumor patients. Methods and Materials: Twenty-five patients with low-grade glioma, high-grade glioma, or benign tumor treated with RT were studied using diffusion tensor magnetic resonance imaging. The biologically corrected doses ranged from 50 to 81 Gy. The temporal changes were assessed before, during, and to 45 weeks after the start of RT. The mean diffusivity of water (), fractional anisotropy of diffusion, diffusivity perpendicular ({lambda}{sub perpendicular}) and parallel ({lambda}{sub parallel}) to white matter fibers were calculated in normal-appearing genu and splenium of the corpus callosum. Results: In the genu and splenium, fractional anisotropy decreased and , {lambda}{sub parallel}, {lambda}{sub -perpendicular} increased linearly and significantly with time (p < 0.01). At 45 weeks after the start of RT, {lambda}{sub -perpendicular} had increased {approx}30% in the genu and splenium, and {lambda}{sub parallel} had increased 5% in the genu and 9% in the splenium, suggesting that demyelination is predominant. The increases in {lambda}{sub perpendicular} and {lambda}{sub parallel} were dose dependent, starting at 3 weeks and continuing to 32 weeks from the start of RT. The dose-dependent increase in {lambda}{sub perpendicular} and {lambda}{sub parallel} was not sustained after 32 weeks, indicating the transition from focal to diffuse effects. Conclusion: The acute and subacute changes in normal-appearing white matter fibers indicate radiation-induced demyelination and mild structural degradation of axonal fibers. The structural changes after RT are progressive, with early dose-dependent demyelination and subsequent diffuse dose-independent demyelination and mild axonal degradation. Diffusion tensor magnetic resonance imaging is potentially a biomarker for the assessment of radiation-induced white matter injury.

Nagesh, Vijaya [Department of Radiation Oncology, University of Michigan Medical School, Ann Arbor, MI (United States)], E-mail: vnagesh@med.umich.edu; Tsien, Christina I. [Department of Radiation Oncology, University of Michigan Medical School, Ann Arbor, MI (United States); Chenevert, Thomas L.; Ross, Brian D. [Department of Radiology, University of Michigan Medical School, Ann Arbor, MI (United States); Lawrence, Theodore S. [Department of Radiation Oncology, University of Michigan Medical School, Ann Arbor, MI (United States); Junick, Larry [Department of Neurology, 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)

2008-03-15

164

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

2012-12-27

165

Giant planet formation by disc instability: flux-limited radiative diffusion and protostellar wobbles  

NASA Astrophysics Data System (ADS)

Giant planet formation by gravitational disc instabilities has become theoretically and observationally acceptable at large distances, but remains theoretically contentious at distances inside about 20 au. Several new three-dimensional hydrodynamics models are presented, where radiative transfer is handled in the flux-limited diffusion approximation from the very start of the model, rather than being employed only after clumps have begun to form. The three models show that the use of the flux limiter has little appreciable effect on the early evolution of a disc instability, in agreement with the conclusions of the previous models, which studied later phases. In addition, two new models are presented where the central protostar is either held fixed or is allowed to wobble in such a manner as to preserve the centre of mass of the star-disc system. While spiral arms and clumps form in both models, the wobbling protostar model appears to be better able to form self-gravitating clumps that could contract to form gas giant protoplanets. Combined with previous results, the new models imply that disc instability should be able to form self-gravitating clumps inside, as well as outside, 20 au in suitably massive and cool protoplanetary discs.

Boss, A. P.

2012-01-01

166

The Radiation Transport Conundrum in Radiation Hydrodynamics  

SciTech Connect

The summary of this paper is: (1) The conundrum in the title is whether to treat radiation in the lab frame or the comoving frame in a radiation-hydrodynamic problem; (2) Several of the difficulties are associated with combining a somewhat relativistic treatment of radiation with a non-relativistic treatment of hydrodynamics; (3) The principal problem is a tradeoff between easily obtaining the correct diffusion limit and describing free-streaming radiation with the correct wave speed; (4) The computational problems of the comoving-frame formulation in more than one dimension, and the difficulty of obtaining both exact conservation and full u/c accuracy argue against this method; (5) As the interest in multi-D increases, as well as the power of computers, the lab-frame method is becoming more attractive; and (6) The Monte Carlo method combines the advantages of both lab-frame and comoving-frame approaches, its only disadvantage being cost.

Castor, J I

2005-03-18

167

Radiation Safety  

Center for Food Safety and Applied Nutrition (CFSAN)

... Safe and Unaffected by Radiation Contamination from Japanese Nuclear Power Plant Incident; US Monitoring Control Strategy Explained (PDF ... More results from www.fda.gov/food/recalls,%20outbreaks%20&%20emergencies/emergencies

168

Healthful radiation  

SciTech Connect

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

Agard, E.T. [Flowers Hospital, Sylvania, OH (United States)

1997-01-01

169

Blackbody Radiation  

NSDL National Science Digital Library

This website, from the University of Winnipeg, offers an explanation of blackbody radiation. The page also provides a brief history, describing its discovery and its implications in modern physics. Several graphs and images are included to aid in the explanation.

2008-09-10

170

Radiation Emergencies  

MedlinePLUS

... EMS Providers Related Links Natural Disasters & Severe Weather Earthquakes Extreme Heat Floods Hurricanes Preparedness Get Supplies Make ... see what you can do. CDC Responds to Earthquake, Tsunami, and Radiation Release in Japan Information on ...

171

RADIATION DETECTOR  

DOEpatents

A radiation detector of the type is described wherein a condenser is directly connected to the electrodes for the purpose of performing the dual function of a guard ring and to provide capacitance coupling for resetting the detector system.

Wilson, H.N.; Glass, F.M.

1960-05-10

172

Radiation Fog  

NSDL National Science Digital Library

This is the first instructional component to be published in the Physical Processes Professional Competency Unit of the Forecasting Low-Altitude Clouds and Fog for Aviation Operations Professional Development Series. The learning modules in this professional competency unit will help aviation forecasters gain more familiarity with the physical concepts and atmospheric conditions related to fog and low stratus life cycles. Such understanding, in turn, can help forecasters more efficiently and accurately evaluate the ability of a given atmospheric environment to generate and/or maintain radiation fog. Radiation Fog presents 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.

Spangler, Tim

2000-12-01

173

Radiation Emergencies  

Center for Drug Evaluation (CDER)

... Safety (3/2011); Radiation Emergencies (Centers for Disease Control and Prevention). ... increase the rates of elimination of these substances from the ... More results from www.fda.gov/drugs/emergencypreparedness/bioterrorismanddrugpreparedness

174

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

SciTech Connect

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

Belyaev, A. E. [National Academy of Sciences of Ukraine, Lashkaryov Institute of Semiconductor Physics (Ukraine); Boltovets, N. S. [Orion State Enterprise Research Institute (Ukraine); Konakova, R. V., E-mail: konakova@isp.kiev.ua; Milenin, V. V. [National Academy of Sciences of Ukraine, Lashkaryov Institute of Semiconductor Physics (Ukraine); Sveshnikov, Yu. N. [Elma-Malachite Close Corporation (Russian Federation); Sheremet, V. N. [National Academy of Sciences of Ukraine, Lashkaryov Institute of Semiconductor Physics (Ukraine)

2010-04-15

175

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

176

R-CHOP with dose-attenuated radiation therapy could induce good prognosis in gastric diffuse large B cell lymphoma  

PubMed Central

Background The treatment strategy for gastric diffuse large cell lymphoma (DLBCL) has not been standardized in such as to the cycles of chemotherapy, dose of radiation, or necessity for the surgery. Although the results of CHOP or R-CHOP treatments have demonstrated the good prognosis, the treatments have been controversial in many cases. Methods We retrospectively analyzed 40 gastric DLBCL patients receiving chemotherapy with or without radiation in our institute. Those in stages II-IV were treated with six cycles of R-CHOP without radiation; for those in stage I, we administered three cycles of R-CHOP with radiation. Results The three-year overall survival (OS) and progression-free survival (PFS) rates were 95.2 and 91.8%, respectively. Those in stage I obtained 100% of OS. The radiation dose prescribed was 30.6?Gy for CR cases and 39.6 to 40?Gy for PR after chemotherapy. Although survival rates tended to correlate with staging groups or age-adjusted IPI classifications, multivariate statistical analysis did not show clear differences. All 14 patients with initial bleeding were successfully managed without surgery during treatment. Conclusion R-CHOP therapy was very effective for gastric DLBCL. It may be not necessary to use more than 30.6?Gy of radiotherapy in the highly chemo-sensitive cases. Less toxic treatments should be made available to gastric DLBCL patients.

2012-01-01

177

Radiation Therapy (For Parents)  

MedlinePLUS

... have many questions and concerns about it. About Radiation Therapy In radiation therapy, high-energy radiation from ... to remove tumors or cancerous areas. Continue How Radiation Is Given Radiation therapy is administered two ways: ...

178

Radiation Doses in Perspective  

MedlinePLUS

... Health Effects Ionizing & Non-Ionizing Radiation Understanding Radiation: Radiation Doses in Perspective Health Effects Main Page Exposure ... Sources Doses from Common Radiation Sources Average U.S. Radiation Doses and Sources All of us are exposed ...

179

An anisotropic model for diffuse radiation incident on slopes of different orientations and possible applications to CPC's  

SciTech Connect

Based on a simple description of the sky dome, a model for estimating diffuse on sloping surfaces, once knowing this value on the horizontal, is developed. Its parameters are established from the analysis of solar radiation data on seven sloping sensors. Tests against data show that substantial improvement is achieved over the isotropic model for any collector slope or orientation. The simple geometry of the model offers the possibility of applications to collectors with limited fields of view such as CPC's.

Perez, R.R.; Scott, J.T.; Stewart, R.

1983-06-01

180

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

SciTech Connect

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

Zeng, Q.-S. [Department of Radiology, Qilu Hospital of Shandong University, Jinan (China)]. E-mail: nanwushan@yahoo.com; Li, C.-F. [Department of Radiology, Qilu Hospital of Shandong University, Jinan (China); Liu Hong [Department of Radiotherapy, Qilu Hospital of Shandong University, Jinan (China); Zhen, J.-H. [Department of Pathology, Qilu Hospital of Shandong University, Jinan (China); Feng, D.-C. [Department of Radiology, Qilu Hospital of Shandong University, Jinan (China)

2007-05-01

181

Dynamic modeling of radiation belt electrons by radial diffusion simulation for a 2 month interval following the 24 March 1991 storm injection  

Microsoft Academic Search

Diffusive radial transport of radiation belt electrons with variable outer boundary is computed using Brautigam and Albert (2000) diffusion coefficients parameterized by Kp, modeling power level at ULF wave frequencies in the range of MeV electron drift periods. We analyzed radial diffusion during a relatively quiet 2 month interval following the 24 March 1991, prompt injection to form a new

Feifei Chu; Mary K. Hudson; Paul Haines; Yuri Shprits

2010-01-01

182

(Radiation protection)  

SciTech Connect

The traveler attended the Seventh Congress of the International Radiation Protection Association (IRPA) in Sydney, Australia, April 11--15, 1988. This conference consisted of a comprehensive technical program with oral and poster presentations in all areas of radiation protection including several topics which were of special interest to the traveler; e.g., neutron dosimetry, personnel dosimetry and instrumentation, radiobiology, and radiation accidents. Besides attending technical sessions, the traveler presented a paper on results and implications of neutron personnel dosimetry intercomparison studies conducted since 1974 at the Oak Ridge National Laboratory (ORNL). During the meeting, the traveler discussed possible future collaborative research efforts with scientists from several countries and obtained commitments for an ORNL-coordinated radiation protection conference planned for November of 1988. Through the conference attendance and discussions with dosimetry researchers, the traveler gained information concerning directions and philosophies in radiation protection and dosimetry and made preliminary plans for future cooperative efforts which will be directly related to Department of Energy (DOE) programs.

Swaja, R.E.

1988-05-06

183

Radiation Damage Workshop  

SciTech Connect

The availability of data regarding the radiation behavior of GaAs and silicon solar cells is discussed as well as efforts to provide sufficient information. Other materials are considered too immature for reasonable radiation evaluation. The lack of concern over the possible catastrophic radiation degradation in cascade cells is a potentially serious problem. Lithium counterdoping shows potential for removing damage in irradiated P-type material, although initial efficiencies are not comparable to current state of the art. The possibility of refining the lithium doping method to maintain high initial efficiencies and combining it with radiation tolerant structures such as thin BSF cells or vertical junction cells could provide a substantial improvement in EOL efficiencies. Laser annealing of junctions, either those formed ion implantation or diffusion, may not only improve initial cell performance but might also reduce the radiation degradation rate.

Stella, P.M.

1984-01-01

184

Problems in astrophysical radiation hydrodynamics  

SciTech Connect

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

Castor, J.I.

1983-09-14

185

RADIATION INTEGRATOR  

DOEpatents

Radiation detecting and measuring systems, particularly a compact, integrating, background monitor, are discussed. One of the principal features of the system is the use of an electrometer tube where the input of the tube is directly connected to an electrode of the radiation detector and a capacitor is coupled to the tube input. When a predetermined quantity of radiation has been integrated, a trigger signal is fed to a recorder and a charge is delivered to the capacitor to render the tube inoperative. The capacitor is then recharged for the next period of operation. With this arrangement there is a substantial reduction in lead lengths and the principal components may be enclosed and hermetically sealed to insure low leakage.

Glass, F.M.; Wilson, H.N.

1959-02-17

186

Radiation effects.  

PubMed

International Commission on Radiological Protection (ICRP) Committee 1 (C1) considers the risk of induction of cancer and heritable disease; the underlying mechanisms of radiation action; and the risks, severity, and mechanisms of induction of tissue reactions (formerly 'deterministic effects'). C1 relies upon the interpretation of current knowledge of radio-epidemiological studies; current information on the underlying mechanisms of diseases and radiation-induced disease; and current radiobiological studies at the whole animal, tissue, cell, and molecular levels. This overview will describe the activities of C1 in the context of the 2007 Recommendations of ICRP. In particular, the conclusions from the most recent C1 Task Group deliberations on radon and lung cancer, and tissue reactions will be discussed. Other activities are described in summary fashion to illustrate those areas that C1 judge to be likely to influence the development of the risk estimates and nominal risk coefficients used for radiation protection purposes. PMID:23088999

Preston, R J

2012-08-22

187

Radiation limits  

SciTech Connect

Recently several changes were made to the regulations governing the limits of allowable exposure to radiation for industrial radiographers and nuclear power plant workers. Even though these regulations effect people who have been trained and educated about radiation`s dangers, changes still bring up many common questions that may not be readily answered by the regulations themselves. This paper will attempt to answer some of the more common and relevant questions that are being asked in industry. Who is involved in setting the regulations and standards? (Who are ``They?``) What are the differences between the old and the new regulations? Why did the regulations change? How do ``They`` know what is safe? Have these standards been changed before? Will there be future changes?

Hassard, M. [Salt Lake Community Coll., Salt Lake City, UT (United States)

1997-09-01

188

Galactic Positron Annihilation Radiation  

NASA Astrophysics Data System (ADS)

Nine years of observations with the CGRO/OSSE instrument have allowed the first maps of positron annihilation radiation. The extraction of annihilation radiation from a complex spectrum composed of both compact and diffuse sources depends upon the unique spectral signatures of 511 keV line and positronium continuum emissions. We report here results of a re-analysis of OSSE obtained spectra of the galactic center region. We show updated maps of annihilation radiation, and discuss how these maps influence the interpretation of suggested sources of galactic positrons.

Milne, P. A.; Kurfess, J. D.; Strickman, M. S.; Leising, M. D.

2002-05-01

189

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. 5 figs.

Hunt, A.J.

1983-09-13

190

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

191

Modeling errors in diffuse-sky radiation: Vector vs scalar treatment  

Microsoft Academic Search

Radiative transfer calculations that utilize the scalar approximation of light produce intensity errors as large as 10% in the case of pure Rayleigh scattering. This modeling error, which arises primarily from second order scattering, is greatly reduced for flux and albedo results because of error cancellation brought about by integration over scattering angle. However, polarized light scattered from an underlying

A. A. Lacis; J. Chowdhary; M. I. Mishchenko; B. Cairns

1998-01-01

192

Comparative 2D Radiation MHD Simulations of Argon Gas Puff Z-pinch Plasma Experiments on the Sandia Z Machine Using the Radiative Diffusion and CRE Transport Models  

Microsoft Academic Search

The recent development of the computationally efficient tabulated collisional radiative equilibrium (TCRE) radiation transport model(J.W. Thornhill, J.P. Apruzese, J. Davis, R.W. Clark, A.L. Velikovich, J.L. Giuliani, Jr., Y.K. Chong, K.G. Whitney, C. Deeney, C.A. Coverdale and F.L. Cochran, Phys. Plasmas 7, 3480 (2001).) has made possible full multidimensional radiation MHD simulations of hot dense Z-pinch plasmas with a realistic description

Y. K. Chong; J. W. Thornhill Giuliani Jr.; J. P. Apruzese; R. E. Terry; J. Davis

2001-01-01

193

Radiation dermatitis  

SciTech Connect

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

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

1987-04-01

194

The Effects of Shading and Diffuse Radiation in Estimating Carbon and Water Fluxes in Tropical and Midlatitude Sites  

NASA Astrophysics Data System (ADS)

The interactions between radiation, water, and carbon are a crucial component in determining terrestrial carbon and water fluxes. In this paper, we will present evidence to demonstrate the close relationship between these processes in an integrated climate system using the Simplified Simple Biosphere Model (SSiB, Xue et al., 1991). The SSiB implemented Collatz et al' (1991, 1992) parameterizations of plant photosynthesis and stomatal conductance to consider CO2 assimilation of vegetation. Quasi-analytical solutions of these parameterizations were developed (Zhan et al., 2003) to improve the computational efficiency and to produce stable solutions for long-term simulations in GCMs and regional models. We tested this enhanced SSiB using observational data from LBA, Boreal, and AmeriFux sites. The results indicated that the model in general produced a higher than normal rate of photosynthesis which led to an overly large transpiration. We examined model performance and found that this was mainly caused by the scaling methodology. In our earlier approach described above, the sunlit and shaded leaf areas were not considered. Furthermore, only direct radiation effect was included in the scaling equation, which was adapted from SiB2. Diffuse radiation, which arises from atmospheric scattering and from scattering within the canopy, has been shown to have a crucial role in the photosynthetic process (e.g., Norman, 1982; Baldocchi, 1997). Therefore, we developed a new parameterization for shading and scaling to more realistically simulate the land/atmosphere interaction processes. The shading parameterization is based on Norman's approach (mainly relies on solar zenith angle), but we further take vegetation properties and solar radiative transfer property within canopy into consideration. The scaling method considers the effects of both direct and diffuse radiations. We have tested the new method using the observational data from the LBA experiment ( 2000) and the Boreal experiments (1996). This new method substantially improved the simulations of daily mean carbon and water fluxes and their diurnal variations, especially in the tropical area. For example, in the LBA experiment, the root-mean-square (RMS) error for the latent heat flux and the carbon flux are 15.1 w m-2 and 2.9 mmol m-2 s-1, respectively, which are much smaller than the RMS error 45.4 w m-2 and 12.7 m mol m-2 s-1 in the simulation with the old method. Experiments are also conducted to comprehensively test the effects of soil moisture, diffuse radiation, and vegetation properties in estimating the variability of carbon and water fluxes.

Xue, Y.; de Sales, F.; Zhan, X.; Collatz, J.

2003-12-01

195

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

NASA Astrophysics Data System (ADS)

We use the first data release from the SINGG H? survey of H I-selected galaxies to study the quantitative behavior of the diffuse, warm ionized medium (WIM) across the range of properties represented by these 109 galaxies. The mean fraction fWIM of diffuse ionized gas in this sample is 0.59+/-0.19, slightly higher than found in previous samples. Since lower surface brightness galaxies tend to have higher fWIM, we believe that most of this difference is due to selection effects favoring large, optically bright, nearby galaxies with high star formation rates. As found in previous studies, there is no appreciable correlation with Hubble type or total star formation rate. However, we find that starburst galaxies, defined here by an H? surface brightness >2.5×1039 erg s-1 kpc-2 within the H? half-light radius, do show much lower fractions of diffuse H? emission. The cause apparently is not dominated by a lower fraction of field OB stars. However, it is qualitatively consistent with an expected escape of ionizing radiation above a threshold star formation rate, predicted from our model in which the ISM is shredded by pressure-driven supernova feedback. The H I gas fractions in the starburst galaxies are also lower, suggesting that the starbursts are consuming and ionizing all the gas, and thus promoting regions of density-bounded ionization. If true, these effects imply that some amount of Lyman continuum radiation is escaping from most starburst galaxies, and that WIM properties and outflows from mechanical feedback are likely to be pressure-driven. However, in view of previous studies showing that the escape fraction of ionizing radiation is generally low, it is likely that other factors also drive the low fractions of diffuse ionized gas in starbursts.

Oey, M. S.; Meurer, G. R.; Yelda, S.; Furst, E. J.; Caballero-Nieves, S. M.; Hanish, D. J.; Levesque, E. M.; Thilker, D. A.; Walth, G. L.; Bland-Hawthorn, J.; Dopita, M. A.; Ferguson, H. C.; Heckman, T. M.; Doyle, M. T.; Drinkwater, M. J.; Freeman, K. C.; Kennicutt, R. C., Jr.; Kilborn, V. A.; Knezek, P. M.; Koribalski, B.; Meyer, M.; Putman, M. E.; Ryan-Weber, E. V.; Smith, R. C.; Staveley-Smith, L.; Webster, R. L.; Werk, J.; Zwaan, M. A.

2007-06-01

196

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

197

Counterbalanced radiation detection system  

SciTech Connect

A counterbalanced radiation detection system is described comprising: (a) a stand; (b) a first radiation detector; (c) a first radiation detector arm means for tiltably connecting the first radiation detector with the stand; (d) a second radiation detector; (e) a second radiation detector arm means for tiltably connecting the second radiation detector with the stand, whereby the tilting angles of the radiation detector arm means define a distance between the radiation detectors; and (f) a torque transforming means connected between the first and second radiation detector arm means for transforming the torque created by one of the radiation detectors in a sense opposed to the torque created by the other radiation detector.

Platz, W.

1987-03-24

198

Ionizing radiation  

Technology Transfer Automated Retrieval System (TEKTRAN)

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

199

RADIATION DOSIMETER  

Microsoft Academic Search

An improvement was made in the determination of amounts of ionizing ; radiation, particularly low-energy beta particles of less than 1000 rad total ; dose by means of fluid-phase dosimeter employing a stabilized-- sensitized ; ferrous-ferric colorimetric system in a sulphuric acid medium. The improvement ; in the dosimeter consists of adding to the ferrous-ferric system in ; concentrations of

W. R. Jr. Balkwell; G. D. Jr. Adams

1960-01-01

200

Radiation accidents  

SciTech Connect

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

Saenger, E.L.

1986-09-01

201

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 ...

202

Radiation Belts  

NSDL National Science Digital Library

This article provides an outline of the motion of charged particles in the Earth's magnetic fields, and the Van Allen and outer radiation belts. It summarizes their discovery, their properties and their physics, as well as providing links to background materials and additional information. This is part of a large web site on the Exploration of the Earth's Magnetosphere. A Spanish translation is available.

Stern, David

2005-09-19

203

Radiation cataract.  

PubMed

Until very recently, ocular exposure guidelines were based on the assumption that radiation cataract is a deterministic event requiring threshold doses generally greater than 2 Gy. This view was, in part, based on older studies which generally had short follow-up periods, failed to take into account increasing latency as dose decreased, had relatively few subjects with doses below a few Gy, and were not designed to detect early lens changes. Newer findings, including those in populations exposed to much lower radiation doses and in subjects as diverse as astronauts, medical workers, atomic bomb survivors, accidentally exposed individuals, and those undergoing diagnostic or radiotherapeutic procedures, strongly suggest dose-related lens opacification at significantly lower doses. These observations resulted in a recent re-evaluation of current lens occupational exposure guidelines, and a proposed lowering of the presumptive radiation cataract threshold to 0.5 Gy/year and the occupational lens exposure limit to 20 mSv/year, regardless of whether received as an acute, protracted, or chronic exposure. Experimental animal studies support these conclusions and suggest a role for genotoxicity in the development of radiation cataract. Recent findings of a low or even zero threshold for radiation-induced lens opacification are likely to influence current research efforts and directions concerning the cellular and molecular mechanisms underlying this pathology. Furthermore, new guidelines are likely to have significant implications for occupational and/or accidental exposure, and the need for occupational eye protection (e.g. in fields such as interventional medicine). PMID:23089007

Kleiman, N J

2012-08-22

204

Radiative transport in the diffusion approximation: An extension for highly absorbing media and small source-detector separations  

NASA Astrophysics Data System (ADS)

The diffusion approximation to the Boltzmann transport equation is commonly used to analyze data obtained from biomedical optical diagnostic techniques. Unfortunately, this approximation has significant limitations to accurately predict radiative transport in turbid media, which constrains its applicability to highly scattering systems. Here we extend the diffusion approximation in both stationary and frequency-domain cases using an approach initially formulated independently by Prahl [Ph.D. thesis, University of Texas at Austin, 1988 (unpublished)] and Star [in Dosimetry of Laser Radiation in Medicine and Biology, edited by G. J. Müller and D. H. Sliney (SPIE, Bellingham, WA, 1989), pp. 146-154 in Optical-Thermal Response of Laser-Irradiated Tissue, edited by A. J. Welch and M. J. C. van Gemert (Plenum, New York, 1995), pp. 131-206]. The solution is presented in the stationary case for infinite media with a collimated source of finite size exhibiting spherical symmetry. The solution is compared to results given by standard diffusion theory as well as to measurements made in turbid phantoms with reduced single scattering albedos a' ranging from 0.248 to 0.997. Unlike the conventional diffusion approximation, the approach presented here provides accurate descriptions of optical dosimetry in both low and high scattering media. Moreover, it accurately describes the transition from the highly anisotropic light distributions present close to collimated sources to the nearly isotropic light distribution present in the far field. It is postulated that the ability to measure the transition between this near and far field behavior and predict it within a single theoretical framework may allow the separation of the single scattering anisotropy g from the reduced scattering coefficient ?'s. The generalized formulation of diffusion theory presented here may enable the quantitative application of present optical diagnostic techniques to turbid systems which are more highly absorbing and allow these systems to be probed using smaller source-detector separations.

Venugopalan, V.; You, J. S.; Tromberg, B. J.

1998-08-01

205

Radiation Therapy for Osteosarcoma  

MedlinePLUS

... for osteosarcoma Next Topic Clinical trials for osteosarcoma Radiation therapy for osteosarcoma Radiation therapy uses high-energy rays ... major role in treating this disease. External beam radiation therapy This is the type of radiation therapy most ...

206

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 may be used in several ...

207

Conventional MRI at presentation does not predict clinical response to radiation therapy in children with diffuse pontine glioma  

Microsoft Academic Search

Background  Diffuse pontine glioma is a pediatric brain tumor with a median survival time of 1 year and few long-term survivors. Conventional\\u000a MRI has not been shown to predict overall survival. With this dismal prognosis, clinical improvement after radiation therapy\\u000a might be a more relevant issue.\\u000a \\u000a \\u000a \\u000a Objective  To determine whether initial imaging would predict clinical response.\\u000a \\u000a \\u000a \\u000a Materials and methods  We performed a retrospective review

Arthur K. Liu; Jonathan Brandon; Nicholas K. Foreman; Laura Z. Fenton

2009-01-01

208

Radiation Protection  

NSDL National Science Digital Library

Chemotherapy and radiation can be powerful weapons against cancer. But they harm healthy cells as well. Cells of the immune system and G.I. tract are especially vulnerable: instead of repairing the damage, they respond by committing cellular suicide. In contrast, tumor cells have mutations that make them resistant to cell death. Roswell Park Cancer Institute researcher Andrei Gudkov and his colleagues recently harnessed this property to create a new drug.

Science Update (AAAS;)

2008-05-01

209

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

210

Radiation protection in space.  

PubMed

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

Reitz, G; Facius, R; Sandler, H

211

Radiating gravastars  

NASA Astrophysics Data System (ADS)

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.; da Silva, M. F. A.; Villas da Rocha, Jaime F.; Wang, Anzhong

2011-10-01

212

Radiation dosimeters  

SciTech Connect

This patent describes a radiation dosimeter badge having at least a first part and a second part; at least one of the parts including a dosimeter holder for holding at least one luminescent dosimeter; the first and second parts being controllably detachable using a rotatable mechanical connection. It comprises a tamper-resistant means to controllably resist unauthorized detachment of the first and second parts of the dosimeter badge; the tamper-resistance means including a tamper ring which engages to resist movement of a rotatable locking ring which is movable to controllably restrain the second and first parts of the dosimeter badge.

Hoelsher, J.W.; Hegland, J.E.; Braunlich, P.F.; Tetzlaff, W.

1992-01-21

213

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

214

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

215

Evaluation of different radiation and albedo models for the prediction of solar radiation incident on tilted surfaces, for four European locations  

Microsoft Academic Search

The diffuse radiation incident on an inclined surface is composed of both the sky diffuse radiation and the ground-reflected radiation. Depending on the model used to calculate the sky diffuse radiation and the estimated albedo value, it is possible to introduce a significant error in the prediction of the total radiation incident on a tilted surface. Twelve sky diffuse submodels

B. E. Psiloglou; C. A. Balaras; M. Santamouris; D. N. Asimakopoulos

1996-01-01

216

Dependence of diffusive radiative transfer on grain-size, temperature, and Fe-content: Implications for mantle processes  

NASA Astrophysics Data System (ADS)

Locally diffusive, radiative heat transport inside the earth is represented by an effective thermal conductivity (krad,dif), calculated from spectra. Previous geophysical models assumed that emissivity (?) equals unity, which violates local radiative equilibrium in an internally heated, grainy medium. Our new formulation accounts for ? depending on frequency, physical scattering depending on grain-size (d), and for light lost through back-reflections at interfaces. Mantle values of krad,dif are estimated from recent visible spectra of olivine combined with new IR data. The following trends hold for krad,dif calculated from olivine spectra, and should be equally valid for pyroxene and spinel: (1) pressure is unimportant, (2) radiative thermal conductivity depends non-linearly on d, temperature (T), and Fe2+ content (X), (3) maxima occur in krad,dif(d) when the grains are large enough to emit substantially, but not so large that light is strongly attenuated within a single-grain, (4) the dependence of krad,dif on Fe2+ content parallels that with d because absorption is controlled by the product dX (Beer's law), and (5) a local minimum occurs in krad,dif near 2000 K for d > 2 mm because at that temperature the peak position of the blackbody curve coincides with that of the strongly absorbing Fe2+ peak in the visible. Larger krad,dif exists at lower and higher temperatures because mean free paths are long in the transmitting near-IR and UV spectral regions. As integration smooths over spectral details, the above representation based on olivine becomes increasingly accurate for other phases as grain-size decreases. For conditions expected in the transition zone, ?krad,dif/?T is negative, which is destabilizing [Dubuffet, F., Yuen, D.A., Rainey, E.S.G., 2002. Controlling thermal chaos in the mantle by positive feedback from radiative thermal conductivity. Nonlinear Proc. Geophys. 9, 1 13]. In the lower mantle, photon transport dominates phonon, promoting stable, weak convection. That radiative transfer is linked to chemical composition and grain-size suggests that this process impacts planetary evolution through the non-linear feedback with rheology.

Hofmeister, A. M.

2005-08-01

217

EXISTENCE AND UNIQUENESS OF THE SOLUTION OF THE COUPLED CONDUCTION-RADIATION ENERGY TRANSFER ON DIFFUSE-GRAY SURFACES  

Microsoft Academic Search

This article gives very signi…cant and up-to-date analytical results on the conductive- radiative heat transfer model containing two conducting and opaque materials which are in contact by radiation through a transparent medium bounded by diuse-gray surfaces. Some properties of the radiative integral operator will be presented. The main emphasis of this work deals also with the question of existence and

Naji Qatanani; Amjad Barham; Qasem Heeh

218

Handling of Radiation Accidents.  

National Technical Information Service (NTIS)

The book deals with one of the most important questions in the practice of radiation safety: the radiation hazards. Chapter I ''Radiation hazards - fundamental concepts, determination and examples'' gives the definition of the concept ''hazard'' and the c...

M. A. Mikhajlov G. Vasilev

1978-01-01

219

Solar radiation resource assessment  

SciTech Connect

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

Not Available

1990-11-01

220

On the diffuse fraction of daily and monthly global radiation for the island of Cyprus  

Microsoft Academic Search

Six years of hourly global and diffuse irradiation measurements on a horizontal surface performed at Athalassa, Cyprus, are used to establish a relationship between the daily diffuse fraction and the daily clearness index. Two types of correlations—yearly and seasonal—have been developed. These correlations, of first and third order in the clearness index are compared to the various correlations established by

C. P. Jacovides; L. Hadjioannou; S. Pashiardis; L. Stefanou

1996-01-01

221

Boundary of modulation diffusion and stochastic instability of high energy protons in inner radiation belt  

NASA Astrophysics Data System (ADS)

Modulation diffusion, which is related to the multiple structure of nonlinear resonances between the cyclotron rotation and higher harmonics of the longitudinal particle oscillations can occur in addition to the Arnold diffusion. The limiting case of these instabilities is stochastic instability involving the overlapping of the stochastic layers of nonlinear resonances. The particle losses are described by different diffusion coefficients, depending on the type of instability, and so it is of practical importance to know the boundaries of the regions of existence of these instabilities as precisely as possible. The modulation diffusion and stochastic instability boundary of high energy particles are determined for the actual geomagnetic field using a fourth order Runge-Kutta-Gills approximation and a RYaD-1040 computer for the case of 400 MeV protons. The available experimental data are in agreement with the calculated values, yielding an upper limit of the stochastic instability for pitch angles of less than about 30 deg.

Amirkhanov, I. V.; Gusev, A. A.; Ilin, V. D.; Ilina, A. N.; Pugacheva, G. I.

1985-03-01

222

Solar radiation modelling  

NASA Astrophysics Data System (ADS)

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

Zakšek, Klemen; Podobnikar, Tomaž; Oštir, Krištof

2005-03-01

223

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

224

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

225

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

226

Why "Radiation Oncology"  

PubMed Central

Radiotherapy continues to be a major treatment for solid tumours and is a cornerstone of modern oncology. The term 'radiation oncology' describes the integration of radiation therapy into the complexity of multi-modal therapy. Over the last ten years the crucial role of radiation therapy as part of multi-modality protocols in cancer care has been documented in numerous Phase III trials. Advances in treatment technology as well as the underlying biology of tumour resistance mechanisms will further strengthen the role of radiation oncology. The scientific role of radiation oncology is reflected by the increase in the number of papers related to radiation oncology in resources like Medline. In order to reflect the growing scientific importance of radiation oncology, radiation physics and radiation biology, we have initiated Radiation Oncology as the first open access journal in the field. Open access allows for a rapid and transparent publication process together with an unequalled opportunity to reach the widest reader spectrum possible.

Belka, Claus; Camphausen, Kevin A

2006-01-01

227

Radiation transport calculations for cosmic radiation.  

PubMed

The radiation environment inside and near spacecraft consists of various components of primary radiation in space and secondary radiation produced by the interaction of the primary radiation with the walls and equipment of the spacecraft. Radiation fields inside astronauts are different from those outside them, because of the body's self-shielding as well as the nuclear fragmentation reactions occurring in the human body. Several computer codes have been developed to simulate the physical processes of the coupled transport of protons, high-charge and high-energy nuclei, and the secondary radiation produced in atomic and nuclear collision processes in matter. These computer codes have been used in various space radiation protection applications: shielding design for spacecraft and planetary habitats, simulation of instrument and detector responses, analysis of absorbed doses and quality factors in organs and tissues, and study of biological effects. This paper focuses on the methods and computer codes used for radiation transport calculations on cosmic radiation, and their application to the analysis of radiation fields inside spacecraft, evaluation of organ doses in the human body, and calculation of dose conversion coefficients using the reference phantoms defined in ICRP Publication 110. PMID:23089013

Endo, A; Sato, T

2012-08-22

228

The radiation stimulated diffusion role in high dose, low energy, high temperature ion implantation  

Microsoft Academic Search

A low energy, high dose and temperature ion implantation modeling method is presented. The diffusion equations for impurity and non-equilibrium vacancies are solved taking into account the source functions for impurity atoms and vacancies and the recession of surface due to sputtering. The source functions as well as the sputtering yields and the surface moving velocity are determined from atom

S. H. Valiev; T. S. Pugacheva; F. G. Jurabekova; S. A. Lem; Y. Miyagawa

1997-01-01

229

The radiation stimulated diffusion role in high dose, low energy, high temperature ion implantation  

Microsoft Academic Search

A low energy, high dose and temperature ion implantation modeling method is presented. The diffusion equations for impurity and non-equilibrium vacancies are solved taking into account the source functions for impurity atoms and vacancies and the recession of surface due to sputtering. The source functions as well as the sputtering yields acid the surface moving velocity are determined from atom

F. G. Jurabekova; S. A. Lem; T. S. Pugacheva; S. H. Valiev; Y. Miyagawa

1997-01-01

230

On the diffuse fraction of daily and monthly global radiation for the island of Cyprus  

SciTech Connect

Six years of hourly global and diffuse irradiation measurements on a horizontal surface performed at Athalassa, Cyprus, are used to establish a relationship between the daily diffuse fraction and the daily clearness index. Two types of correlations - yearly and seasonal - have been developed. These correlations, of first and third order in the clearness index are compared to the various correlations established by Collares-Pereira and Rabl (1979), Newland (1989), Erbs et al. (1982), Rao et al. (1984), Page (1961), Liu and Jordan (1960) and Lalas et al. (1987). The comparison has been performed in terms of the widely used statistical indicators (MBE) and (RMSE) errors; and additional statistical indicator, the t-statistic, combining the earlier indicators, is introduced. The results indicate that the proposed yearly correlation matches the earlier correlations quite closely and all correlations examined yield results that are statistically significant. For large K{sub t} > 0.60 values, most of the earlier correlations exhibit a slight tendency to systematically overestimate the diffuse fraction. This marginal disagreement between the earlier correlations and the proposed model is probably significantly affected by the clear sky conditions that prevail over Cyprus for most of the time as well as atmospheric humidity content. It is clear that the standard correlations examined in this analysis appear to be location-independent models for diffuse irradiation predictions, at least for the Cyprus case. 13 refs., 5 figs., 4 tabs.

Jacovides, C.P. [Univ. of Athens (Greece); Hadjioannou, L.; Pashiardis, S.; Stefanou, L. [Meteorological Service of Cyprus, Nicosia (Cyprus)

1996-06-01

231

Numerical study on the effect of gravity on flame shape and radiation in laminar diffusion flames  

Microsoft Academic Search

The effects of gravity and buoyancy on the structure and dynamics of laminar diffusion flames is considered. Com- bustion phenomena display significant changes under microgravity conditions as compared to situations involving normal gravitational acceleration. The major cause of these changes is the suppression of buoyancy-induced effects. At elevated pressures on earth, the influence of buoyancy increases sharply with pressure. From

Marc R. J. Charest; Clinton P. T. Groth; Omer L. Gulder

232

Radiation Effects on Free Convection Flow past an Impulsively Started Infinite Vertical Plate with Ramped Wall Temperature and Constant Mass Diffusion  

NASA Astrophysics Data System (ADS)

The interaction of free convection with thermal radiation of a viscous incompressible unsteady flow past an impulsively started infinite vertical plate in the presence of chemical species concentration and a temperature boundary condition which follows a ramp function up until some specified time and then remains constant is analyzed. The fluid is assumed to be gray, emitting-absorbing but no-scattering medium and the optically thick radiation limit is considered. The Cogley-Vincenti-Gilles formulation is adopted to simulate the radiation component of heat transfer. The dimensionless governing equations are solved using Laplace transform technique. The velocity, the temperature and the concentration profiles are shown on graphs for different gasses. The variation of skin-friction is also shown in a table. The effects of different parameters like Radiation parameter ( F ), thermal Grashof number ( Gr ), Prandtl number (Pr), Schmidt number (Sc), mass to thermal buoyancy ratio parameter ( N ) for the three cases N = 0 (the buoyancy force is due to thermal diffusion only), N>0 (the mass buoyancy force acts in the same direction of thermal buoyancy force) and N<0 (the mass buoyancy force acts in the opposite direction of thermal buoyancy force) and time ( t ) are discussed. The interaction of free convection with thermal radiation near a ramped temperature plate has also been compared with the flow near a plate with constant temperature. It is observed that the velocity increases with decreasing radiation parameter.

Narahari, M.; Bég, O. Anwar

2010-06-01

233

A mathematical note on the slow diffusive character of the long-wave radiative transfer in the stable atmospheric nocturnal boundary layer  

NASA Astrophysics Data System (ADS)

A simple equation of diffusion is derived from the longwave radiative flux transfer equation for the atmospheric stable nocturnal boundary layer. This simplification is valid with clear-sky conditions, light wind speeds and near the top of the inversion layer which has already been established. The known physical behavior of such a layer in the given conditions (the weak and slow destabilization, and spreading of the top of the inversion layer) is explained by this simple equation of mathematical physics instead of a complicated expression written in terms of the net longwave radiative flux divergence.

Grisogono, Branko

1990-08-01

234

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

235

Radiation applications: An overview  

SciTech Connect

Radiation has been successfully utilized for medical, industrial, and research applications since Roentgen first discovered X rays in the late 19th century. Today, intense fields of electron, photon, and neutron radiation are used for defense applications, and industrial processing, and both radiation sources and focused beams of radiation are routinely used in medicine for therapy and imaging. These advances in radiation technology have been coupled with the development of high-power reactors and high-power accelerators as well as continued improvements in the dosimetry of the delivered radiation. Radiation also can be a problem that must be dealt with. Aside from the obvious need to shield people and critical apparatus from the harmful effects of ionizing radiation, there are cases where the system must be designed to operate successfully in a radiation field. Reactor components such as fuel, internals, and pressure vessels must operate in neutron fields; fusion systems must operate in intense high-energy neutron fields; microelectronics used in space must operate in electron, proton, and cosmic ray fields; and accelerator components must operate in proton, neutron, and photon fields. Frequently, these components cannot be tested directly in the radiation fields to which they will be subjected, so simulation of the radiation fields with reactors, accelerators, or radiation sources has been developed to cope with this problem. This paper focuses on current applications of radiation processing, radiation effects in electronics, and radiation imaging.

Block, R.C. (Rensselaer Polytechnic Institute, Troy, NY (United States))

1993-01-01

236

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

237

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

238

Empirical relationship between Kubelka-Munk and radiative transfer coefficients for extracting optical parameters of tissues in diffusive and nondiffusive regimes.  

PubMed

Kubelka–Munk (K-M) theory is a phenomenological light transport theory that provides analytical expressions for reflectance and transmittance of diffusive substrates such as tissues. Many authors have derived relations between coefficients of K-M theory and that of the more fundamental radiative transfer equations. These relations are valid only in diffusive light transport regime where scattering dominates over absorption. They also fail near boundaries where incident beams are not diffusive. By measuring total transmittance and total reflectance of tissue phantoms with varying optical parameters, we have obtained empirical relations between K-M coefficients and the radiative transport coefficients for integrating sphere-based spectrophotometers that use uniform, nondiffusive incident beams. Our empirical relations show that the K-M scattering coefficients depend only on reduced scattering coefficient (?'s), whereas the K-M absorption coefficient depends on both absorption (?a ) and reduced scattering (?s' ) coefficients of radiative transfer theory. We have shown that these empirical relations are valid in both the diffusive and nondiffusive regimes and can predict total reflectance within an error of 10%. They also can be used to solve the inverse problem of obtaining multiple optical parameters such as chromophore concentration and tissue thickness from the measured reflectance spectra with a maximum accuracy of 90% to 95%. PMID:23214177

Roy, Arindam; Ramasubramaniam, Rajagopal; Gaonkar, Harshavardhan A

2012-11-01

239

Radiation protection guidelines for radiation emergencies  

SciTech Connect

The system of dose limitation and present guidance for emergency workers and guidance for intervention on behalf of the public are discussed. There are three elements for the system of dose limitation: justification, optimization and dose limits. The first element is basically a political process in this country. Justification is based on a risk-benefit analysis, and justification of the use of radioactive materials or radiation is generally not within the authority of radiation protection managers. Radiation protection managers typically assess detriments or harm caused by radiation exposure and have very little expertise in assessing the benefits of a particular practice involving nuclear material.

Lessard, E.T.; Meinhold, C.B.

1986-01-01

240

The evolution of discontinuities in radiating spheres in the diffusion approximation  

SciTech Connect

The evolution of discontinuities in a general relativistic sphere free of singularities is studied. The energy transport mechanism through fluid is diffusive. The distribution of matter is divided by a shock wave front in two regions. The equations of state at both sides of the shock are different, and the solutions are matched on it via the Rankine-Hugoniot conditions. The outer metric joins the Vaidya solution at the boundary surface of the sphere. Exploding models are obtained, and their dynamics are studied using a generalized compressibility coefficient for nonadiabatic systems. 17 refs.

Barreto, W.; Herrera, L.; Nunez, L. (Universidad de Oriente, Cumana (Venezuela) Universidad Central de Venezuela, Caracas (Venezuela) Universidad de los Andes, Merida (Venezuela))

1991-07-01

241

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

242

Non-invasive diffuse reflectance measurements of cutaneous melanin content can predict human sensitivity to ultraviolet radiation.  

PubMed

The diversity of human skin phenotypes and the ubiquitous exposure to ultraviolet radiation (UVR) underscore the need for a non-invasive tool to predict an individual's UVR sensitivity. We analysed correlations between UVR sensitivity, melanin content, diffuse reflectance spectroscopy (DR) and UVR-induced DNA damage in the skin of subjects from three racial/ethnic groups: Asian, black or African American and White. UVR sensitivity was determined by evaluating each subject's response to one minimal erythemal dose (MED) of UVR one day after the exposure. Melanin content was measured using DR and by densitometric analysis of Fontana-Masson staining (FM) in skin biopsies taken from unexposed areas. An individual's UVR sensitivity based on MED was highly correlated with melanin content measured by DR and by FM. Therefore, a predictive model for the non-invasive determination of UVR sensitivity using DR was developed. The MED precision was further improved when we took race/ethnicity into consideration. The use of DR serves as a tool for predicting UVR sensitivity in humans that should be invaluable for determining appropriate UVR doses for therapeutic, diagnostic and/or cosmetic devices. PMID:23528212

Coelho, Sergio G; Zmudzka, Barbara Z; Yin, Lanlan; Miller, Sharon A; Yamaguchi, Yuji; Tadokoro, Taketsugu; Hearing, Vincent J; Beer, Janusz Z

2013-04-01

243

A new radiation stable plastic scintillator  

Microsoft Academic Search

The influence of various components of a plastic scintillator (high concentrations of primary dopant, secondary fluor, diffusion enhancer and stabilizer) on its radiation hardness has been experimentally determined. The diffusion enhancing technique was shown to be the most powerful tool for improving radiation hardness. A new polystyrene scintillator that decreases its light output by only 4% after 2.8 Mrad irradiation

V. G. Senchishin; F. Markley; V. N. Lebedev; V. E. Kovtun; V. S. Koba; A. V. Kuznichenko; V. D. Tizkaja; J. A. Budagov; G. Bellettini; V. P. Seminozhenko; I. I. Zalubovsky; I. E. Chirikov-Zorin

1995-01-01

244

Chemical Reaction Effects on MHD Flow Past a Linearly Accelerated Vertical Plate with Variable Temperature and Mass Diffusion in the Presence of Thermal Radiation  

NASA Astrophysics Data System (ADS)

An exact solution of first order chemical reaction effects on a radiative flow past a linearly accelerated infinite isothermal vertical plate with variable mass diffusion, under the action of a transversely applied magnetic field has been presented. The plate temperature is raised linearly with time and the concentration level near the plate is also raised to C'w linearly with time. The dimensionless governing equations are tackled using the Laplace-transform technique. The velocity, temperature and concentration fields are studied for different physical parameters such as the magnetic field parameter, radiation parameter, chemical reaction parameter, thermal Grashof number, mass Grashof number, Schmidt number, Prandtl number and time. It is observed that velocity increases with decreasing magnetic field parameter or radiation parameter. But the trend is just reversed with respect to the chemical reaction parameter

Muthucumaraswamy, R.; Geetha, E.

2013-08-01

245

Modeling of explosion thermal radiation  

NASA Astrophysics Data System (ADS)

The hydrodynamic and radiation processes accompanying explosions of chemical explosives and fuel-air mixtures have been considered. Computer modeling of the radiation from a fire ball of explosion and a flame of diffusion combustion of a hydrocarbon fuel has been performed. The dependences of the heat flux density from the region occupied by explosion and combustion products on its temperature and geometric characteristics have been determined. Thermal load distributions on targets of different orientations in the vicinity of the energy release zone have been obtained. A comparison of the thermal parameters on radiation detectors with the criteria of thermal affection of people and ignition of combustible materials has been made.

Stepanov, K. L.; Stanchits, L. K.; Stankevich, Yu. A.

2011-01-01

246

Introduction to radiation transport  

SciTech Connect

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

Olson, G.L.

1998-12-31

247

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.

248

Radiation Safety or Radiation Hazard in Norway.  

National Technical Information Service (NTIS)

The report gives a survey of radiation dose (to the whole body or to certain organs) to the Norwegian population, caused by various radiation sources. It also estimates the probable number and category of injuries caused by these doses. Comparative evalua...

E. E. Pochin

1985-01-01

249

Efficient solution of multi-dimensional flux-limited nonequilibrium radiation diffusion coupled to material conduction with second-order time discretization  

Microsoft Academic Search

Many algorithms for the second-order time evolution of the coupled radiation diffusion and material conduction equations have been published. Most of them are cumbersome to implement and much slower computationally than their first-order equivalent algorithms. This paper presents a simpler approach that is both computationally efficient and easy to implement. Second-order behavior can be achieved even when the iteration at

Gordon L. Olson; Gordon L

2007-01-01

250

Serial diffusion tensor imaging to characterize radiation-induced changes in normal-appearing white matter following radiotherapy in patients with adult low-grade gliomas  

Microsoft Academic Search

Purpose  The aim of this study was to ascertain whether diffusion tensor imaging (DTI) metrics—fractional anisotropy (FA), mean diffusivity\\u000a (MD), linear case (CL), planar case (CP), spherical case (CS)—can characterize a threshold dose and temporal evolution of\\u000a changes in normal-appearing white matter (NAWM) of adults with low-grade gliomas (LGGs) treated with radiation therapy (RT).\\u000a \\u000a \\u000a \\u000a Methods and materials  Conventional and DTI imaging were

Mohammad Haris; Shaleen Kumar; Mani Karthick Raj; Koilpillai Joseph Maria Das; Shantanu Sapru; Sanjay Behari; Ram Kishore Singh Rathore; Ponnada A. Narayana; Rakesh Kumar Gupta

2008-01-01

251

Radiation from hard objects  

SciTech Connect

The inference of the diameter of hard objects is insensitive to radiation efficiency. Deductions of radiation efficiency from observations are very sensitive - possibly overly so. Inferences of the initial velocity and trajectory vary similarly, and hence are comparably sensitive.

Canavan, G.H.

1997-02-01

252

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

253

Automated Personnel Radiation Monitor.  

National Technical Information Service (NTIS)

An automated Personnel Low-Level Radiation Portal Monitor has been developed by UNC Nuclear Industries, Inc. It is micro-computer controlled and uses nineteen large gas flow radiation detectors. By employing a micro-computer, sophisticated mathematical an...

S. G. Sterling

1981-01-01

254

Radio Frequency Radiation Hazards.  

National Technical Information Service (NTIS)

Explains the biological (personnel) and non-biological (feed and fuel) effects of RF radiation. The frequency spectrum is explained and the difference between ionizing and non-ionizing radiation is illustrated.

1994-01-01

255

Fundamentals of Radiation Physics.  

National Technical Information Service (NTIS)

The Scientific Medical Effects of Ionizing Radiation Course, conducted once a year, focuses on the latest research about the medical effects of ionizing radiation to help clinicians, health physicists, and medical planners preserve troop health in the fac...

M. S. Smyczynski

2008-01-01

256

Nonionizing Radiation 583.  

National Technical Information Service (NTIS)

This document presents an introductory course on nonionizing radiation intended for industrial hygienists, health physicists, and other professional health personnel. Topics covered in the course include nonionizing radiation sources, the attendant hazard...

1977-01-01

257

Radiative Augmented Combustion.  

National Technical Information Service (NTIS)

Radiative Augmented Combustion has been identified as a potential technique for extending aircraft operating limits associated with combustion processes. This technique is based on the fact that radiation of selected wavelengths is capable of photodissoci...

M. Lavid

1984-01-01

258

Solar Cell Radiation Handbook.  

National Technical Information Service (NTIS)

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...

J. R. Carter H. Y. Tada

1973-01-01

259

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? ...

260

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

261

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 ...

262

Radiation and the Energy Balance: The Role of Radiation.  

National Technical Information Service (NTIS)

The role of radiation, cloud radiation interactions in the climate, and radiation processes in climate change are discussed. The geometrical constraints, calibration issues, and time sampling issues of measuring radiation fluxes, done from space, are cons...

R. Kandel

1991-01-01

263

Synchrotron-radiation research  

SciTech Connect

The use of radiation from synchrotron sources has started a renaissance in materials, physics, chemistry, and biology. Synchrotron radiation has advantages over conventional x rays in that its source brightness is a thousand times greater throughout a continuous energy spectrum, and resonances are produced with specific electron energy levels. Two major synchrotron radiation sources are operated by DOE: the Stanford Synchrotron Radiation Laboratory at SLAC, and the National Synchrotron Light Source at Brookhaven. (DLC)

Cunningham, J.E.

1982-01-01

264

Daily Radiation Balance  

NSDL National Science Digital Library

This lesson is designed to provide students an understanding of the extent to which radiative energy heats and cools the surface of Earth on a daily basis. Students will learn to calculate the total amount of incoming and outgoing radiation over a day. They will learn to determine how balanced the radiative system is over a particular location and try to determine whether the surface is in radiative equilibrium.

265

Planetary Radiation Budgets  

Microsoft Academic Search

The energy state of a planet depends fundamentally on its radiation budget. Measurements made from space over past decades have led to significant revisions of ground-based estimates, both of the reflected fraction (the Bond albedo) of solar radiative flux and of the emitted thermal infrared radiation flux, for the Earth as well as for the other planets. After a brief

Robert Kandel; Michel Viollier

2005-01-01

266

Packet Personal Radiation Monitor.  

National Technical Information Service (NTIS)

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...

J. E. Phelps

1988-01-01

267

RADIATION SITES TECHNICAL WORKGROUP  

EPA Science Inventory

Much of the radiation expertise in EPA is located in the Region Offices. The EPA Radiation Sites Technical Workgroup is an interoffice technical workgroup within EPA which provides a focal point for radiation expertise. The Workgroup has members from each region, as well as the...

268

Hand held radiation detector  

Microsoft Academic Search

A hand-held radiation detector is described for measuring localized radiation at extremely low levels, the detector comprising: a housing including two peripherally engaged, axially extending, tubular members, one of the members being entirely insulative, the other of the members being metallic; a radiation window at one end of the metallic tubular member, the window including a metallic portion in electrical

Wijangco

1984-01-01

269

Radiation Monitoring by Minicomputer.  

National Technical Information Service (NTIS)

Radiation monitoring at the Los Alamos Scientific Laboratory (LASL) ranges from measuring the potential build-up of alpha particle radiation in the offices and laboratories of LASL to the detection of radiation leakage from nuclear tests at the Nevada Tes...

M. Seamons

1977-01-01

270

Radiation degradation of polymethacrylamide  

Microsoft Academic Search

The effects of radiation on polymers have been studied for many years. When polymers are subjected to ultraviolet light or ionizing radiation, chain scission and crosslinking are possible. The radiation degradations of several methacrylate type polymers were investigated. The primary polymer studied was polymethacrylamide (PMAAm). Ultraviolet irradiated PMAAm yielded a five line ESR spectrum with 22 gauss splitting which is

OConnor

1984-01-01

271

Radiation Oncology Annual  

Microsoft Academic Search

Radiation Oncology Annual presents analyses of the latest clinical, technical, and biological advances in the field. Review articles cover new single and combined modality treatments for specific tumors; emerging techniques and uses of radiotherapy; advances in radiation physics; dosimetry; and treatment planning; clinical applications of imaging in radiation oncology clinically relevant radiobiology and experimental radiotherapy findings. Special attention is devoted

T. L. Phillips; W. Wara; D. A. Pistenmaa

1983-01-01

272

Radiation port dermatophytosis  

SciTech Connect

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

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

1988-12-01

273

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

PubMed Central

Quantitative imaging assessment of radiation therapy (RT) for diffuse low-grade gliomas (DLGG) by measuring the velocity of diametric expansion (VDE) over time has never been studied. We assessed the VDE changes following RT and determined whether this parameter can serve as a prognostic factor. We reviewed a consecutive series of 33 adults with supratentorial DLGG treated with first-line RT with available imaging follow-up (median follow-up, 103 months). Before RT, all patients presented with a spontaneous tumor volume increase (positive VDE, mean 5.9 mm/year). After RT, all patients demonstrated a tumor volume decrease (negative VDE, mean, ?16.7 mm/year) during a mean 49-month duration. In univariate analysis, initial tumor volume (>100 cm3), lack of IDH1 expression, p53 expression, high proliferation index, and fast post-RT tumor volume decrease (VDE at ?10 mm/year or faster, fast responders) were associated with a significantly shorter overall survival (OS). The median OS was significantly longer (120.8 months) for slow responders (post-RT VDE slower than ?10.0 mm/year) than for fast responders (47.9 months). In multivariate analysis, fast responders, larger initial tumor volume, lack of IDH1 expression, and p53 expression were independent poor prognostic factors for OS. A high proliferation index was significantly more frequent in the fast responder subgroup than in the slow responder subgroup. We conclude that the pattern of post-RT VDE changes is an independent prognostic factor for DLGG and offers a quantitative parameter to predict long-term outcomes. We propose to monitor individually the post-RT VDE changes using MRI follow-up, with particular attention to fast responders.

Pallud, Johan; Llitjos, Jean-Francois; Dhermain, Frederic; Varlet, Pascale; Dezamis, Edouard; Devaux, Bertrand; Souillard-Scemama, Raphaelle; Sanai, Nader; Koziak, Maria; Page, Philippe; Schlienger, Michel; Daumas-Duport, Catherine; Meder, Jean-Francois; Oppenheim, Catherine; Roux, Francois-Xavier

2012-01-01

274

CRASH: a radiative transfer scheme  

NASA Astrophysics Data System (ADS)

We present a largely improved version of CRASH, a 3D radiative transfer code that treats the effects of ionizing radiation propagating through a given inhomogeneous H/He cosmological density field on the physical conditions of the gas. The code, based on a Monte Carlo technique, self-consistently calculates the time evolution of gas temperature and ionization fractions due to an arbitrary number of point/extended sources and/or diffuse background radiation with given spectra. In addition, the effects of diffuse ionizing radiation following recombinations of ionized atoms have been included. After a complete description of the numerical scheme, to demonstrate the performance, accuracy, convergence and robustness of the code, we present four different test cases designed to investigate specific aspects of radiative transfer: (i) a pure-hydrogen isothermal Strömgren sphere; (ii) realistic Strömgren spheres; (iii) multiple overlapping point sources; and (iv) shadowing of background radiation by an intervening optically thick layer. When possible, detailed quantitative comparison of the results against either analytical solutions or 1D standard photoionization codes has been made, and shows a good level of agreement. For more complicated tests the code yields physically plausible results, which could be eventually checked only by comparison with other similar codes. Finally, we briefly discuss future possible developments and cosmological applications of the code.

Maselli, A.; Ferrara, A.; Ciardi, B.

2003-10-01

275

Radiation Research: Chemistry and Physics.  

National Technical Information Service (NTIS)

Papers in this Proceedings are grouped under the following headings: (1) primary processes in radiation physics and chemistry; (2) radiation chemistry - general chemistry; (3) radiation chemistry - DNA and model systems; (4) radiation chemistry - other mo...

J. J. Broerse G. W. Barendsen H. B. Kal A. J. van der Kogel

1983-01-01

276

Nonionizing Radiation Laboratory Manual (583).  

National Technical Information Service (NTIS)

A laboratory manual for the study of nonionizing radiation, designed for industrial hygienists, health physicists and other health personnel, is presented. Topics include nonionizing radiation sources, radiation hazards, and basic principles of radiation ...

1977-01-01

277

Radiation Therapy for Bone Cancer  

MedlinePLUS

... bone cancer Next Topic Chemotherapy for bone cancer Radiation therapy for bone cancer Radiation therapy uses high- ... control symptoms like pain and swelling. Intensity-modulated radiation therapy Intensity-modulated radiation therapy (IMRT) is an ...

278

Radiation Therapy for Malignant Mesothelioma  

MedlinePLUS

... malignant mesothelioma Next Topic Chemotherapy for malignant mesothelioma Radiation therapy for malignant mesothelioma Radiation therapy uses high- ... this form of treatment more useful. Uses of radiation therapy Radiation therapy may be used in different ...

279

Radiation protection for radiologic technologists.  

PubMed

This article provides a review and update on radiation protection principles. Major topics include the effects of radiation on the body, natural and artificial sources of radiation, the basic principles of radiation protection and recommended dose limits. PMID:10665051

Newman, J

280

Radiation detection system  

DOEpatents

A radiation detection system which utilizes the generation of Cerenkov light in and the transmission of that light longitudinally through fiber optic wave guides in order to transmit intelligence relating to the radiation to a remote location. The wave guides are aligned with respect to charged particle radiation so that the Cerenkov light, which is generated at an angle to the radiation, is accepted by the fiber for transmission therethrough. The Cerenkov radiation is detected, recorded, and analyzed at the other end of the fiber.

Nelson, Melvin A. (Santa Barbara, CA); Davies, Terence J. (Santa Barbara, CA); Morton, III, John R. (Livermore, CA)

1976-01-01

281

RADIATION WAVE DETECTOR  

DOEpatents

The detection of the shape and amplitude of a radiation wave is discussed, particularly an apparatus for automatically indicating at spaced lntervals of time the radiation intensity at a flxed point as a measure of a radiation wave passing the point. The apparatus utilizes a number of photomultiplier tubes surrounding a scintillation type detector, For obtainlng time spaced signals proportional to radiation at predetermined intervals the photolnultiplier tubes are actuated ln sequence following detector incidence of a predetermined radiation level by electronic means. The time spaced signals so produced are then separately amplified and relayed to recording means.

Wouters, L.F.

1958-10-28

282

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

283

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

284

Americans' Average Radiation Exposure  

SciTech Connect

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

NA

2000-08-11

285

Radiation Damage Effects  

NASA Astrophysics Data System (ADS)

Radiation damage is an important issue for the particle detectors operated in a hostile environment where radiations from various sources are expected. This is particularly important for high energy physics detectors designed for the energy and intensity frontiers. This chapter describes the radiation damage effects in scintillating crystals, including the scintillation-mechanism damage, the radiation-induced phosphorescence, and the radiation-induced absorption. The radiation damage mechanism in crystal scintillators is also discussed. While the damage in halides is attributed to the oxygen/hydroxyl contamination, it is the structure defects, such as the oxygen vacancies, which cause the damage in oxides. Various material analysis methods used in investigations of the radiation damage effects as well as the improvement of crystal quality through systematic R&D are also presented.

Zhu, R.-Y.

286

Acute radiation syndrome and chronic radiation syndrome.  

PubMed

Acute radiation syndrome (ARS) or sickness or poisoning or toxicity is induced after a whole body exposure of men to high doses of radiation between 1-12Gy. First symptoms are from the gastrointestinal system, which together with bone marrow are the most sensitive parts of our body. Chronic radiation syndrome (CRS) may be induced by smaller than 1Gy radiation doses or after a mild form of ARS. Prophylaxis and treatment suggestions are described. In cases of ARS, a large part of the exposed population after proper medical care may survive, while without medical care this part of the population will be lost. Prophylaxis may also save another part of the population. PMID:23570025

Grammaticos, Philip; Giannoula, Evanthia; Fountos, George P

287

On the numerical simulation of particle dynamics in the radiation belt: 2. Procedure based on the diagonalization of the diffusion tensor  

NASA Astrophysics Data System (ADS)

In this paper, we conclude the survey and comparison of different numerical methods used to solve the diffusion equation for particle dynamics in the Earth's radiation belt, initiated in Camporeale et al. (2013). Here we focus on the diagonalization procedure introduced by Albert and Young (2005) that, by performing a change of coordinates, solves the diffusion equation in a space where the mixed diffusion terms are null. We describe the diagonalization procedure and its numerical implementation, which is not as straightforward as the implementation of a traditional solver in a rectangular domain. We compare the computing times with and without the diagonalization procedure, and we conclude that this procedure is generally not advantageous from the point of view of computational efficiency.

Camporeale, E.; Delzanno, G. L.; Zaharia, S.; Koller, J.

2013-06-01

288

Complications of radiation therapy  

SciTech Connect

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

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

1985-01-01

289

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

SciTech Connect

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

Pradhan, S. [Laser and Plasma Technology Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Mayya, Y. S. [Environmental Assessment Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Homi Bhabha National Institute, Mumbai 400 094 (India); Jagatap, B. N. [Laser and Plasma Technology Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Homi Bhabha National Institute, Mumbai 400 094 (India)

2007-09-15

290

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

291

Neutron radiative capture  

SciTech Connect

This book presents a description of radiative capture processes at both low and high neutron energies; explains how calculations of the cross sections and spectra can be made and illustrates the techniques of capture measurements to form a coherent picture of the theory and applications of neutron capture. Contents include: Theory of Slow Neutron Radiative Capture: Introduction. Statistical theory of radiative capture. Neutron capture reaction mechanisms. Systematic properties of radiative neutron capture. Applications to stellar nucleosynthesis. Fast Neutron Radiative Capture: Direct and semidirect capture reactions. The compound nucleus model. Experimental results. Methods for calculating Neutron Cross Sections and Gamma-Ray Energy Spectra: Scope. Statistical model calculations. Expressions for El photon strengths. Giant dipole resonance systematics. Summary. Measurement Techniques for Radiative Neutron Capture: Introduction. Capture event detection. Analysis of measuarements. Neutron capture processes in fission reactors: Introduction. Capture in fertile and fissile nuclei. Capture in structural, coolout and shielding materials. Capture in fission product nuclei. The production of higher actinides.

Chrien, R.E.

1983-01-01

292

The flying radiation case  

SciTech Connect

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

Brownell, J.H.; Bowers, R.L. [Los Alamos National Lab., NM (United States). Applied Theoretical and Computational Physics Div.

1997-04-01

293

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

Microsoft Academic Search

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,

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

2010-01-01

294

Solar radiation potential in Turkey  

SciTech Connect

The primary input in solar energy applications is the solar radiation data. In places of interest, the long term correlations can be developed using the other meterological parameters. Bright sunshine hours are the mostly applied parameter. In this work, a quadratic equation of modified Angstrom type is used to estimate the global irradiances of the fifty stations in the country. These stations are located between 36/sup 0/ and 42/sup 0/ N latitudes. Moreover, the information of the beam and diffuse components of radiation on both the hourly and daily basis are necessary for the detailed system analyses. The general approach is to split the daily medium global radiation to its components, and to predict their hourly variations during a day. These values can also be converted to non-horizontal surfaces with the given inclination and orientation. To this end, there exist important relations deducted from the measured data. Among them the interrelationships of Liu and Jordon are applied to predict the hourly radiation components on any plane for the same fifty locations. The most significant computer output tables are collected to form a ''Solar Radiation Handbook of Turkey''. Any required information on solar radiation can be obtained in detail from these tables.

Tasdemiroglu, E.

1983-12-01

295

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

296

Spatially depolarised laser radiation  

SciTech Connect

The properties of polarisation-inhomogeneous laser radiation are considered taking into account its partial polarisation. It is shown that this radiation can be represented by a set of Hermite-Gaussian modes with different intensities and polarisations, and different coherence degrees. Devices having inhomogeneous depolarisation and polarisation are analysed. It is shown that the polarisation structure of polarisation-inhomogeneous radiation is not preserved during its propagation. (laser applications and other topics in quantum electronics)

Ishchenko, E F; Sokolov, A L [Moscow Power Engineering Institute, Moscow (Russian Federation)

2004-01-31

297

MULTIPOINT RADIATION MONITOR  

Microsoft Academic Search

A unique radiation monitor has been developed for performing wide-area field surveys for radiation sources. This device integrates the real-time output of multiple radiation detectors into a hand-held personal computer (e.g., a PDA) containing an intuitive graphical user interface. An independent hardware module supplies high voltage to the detectors and contains a rapid sampling system for transferring the detector count

K Hofstetter; D Donna Beals; K Ken Odell; R Robert Eakle; R Russell Huffman; L Larry Harpring

2006-01-01

298

Stereotactic Body Radiation Therapy  

Microsoft Academic Search

\\u000a Technological advancements in imaging and radiation planning and delivery have made it possible for cranial stereotactic radiosurgery\\u000a techniques to be applied to tumors outside of the brain. Although high-dose radiation therapy may be delivered in a single\\u000a fraction, referred to as extracranial stereotactic radiosurgery (SRS), more often, high-precision radiation is delivered in\\u000a more than one fraction, leading to the field

Laura A. Dawson

299

Solar and Infrared Radiation Station (SIRS) Handbook  

SciTech Connect

The Solar Infrared Radiation Station (SIRS) provides continuous measurements of broadband shortwave (solar) and longwave (atmospheric or infrared) irradiances for downwelling and upwelling components. The following six irradiance measurements are collected from a network of stations to help determine the total radiative flux exchange within the Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) Climate Research Facility: • Direct normal shortwave (solar beam) • Diffuse horizontal shortwave (sky) • Global horizontal shortwave (total hemispheric) • Upwelling shortwave (reflected) • Downwelling longwave (atmospheric infrared) • Upwelling longwave (surface infrared)

Stoffel, T

2005-07-01

300

A software component for estimating solar radiation  

Microsoft Academic Search

GSRad (global solar radiation) is a software component containing models to estimate extra-terrestrial and ground-level solar radiation (global and photosynthetically active; direct, diffuse, and reflected components) from alternative methods. Radiation data are estimated as either 1-h or 24-h values. Moreover, GSRad provides methods to compute clear sky transmissivity, slope and aspect angles of tilted terrains from a grid of elevation

Marcello Donatelli; Laura Carlini; Gianni Bellocchi

2006-01-01

301

Radiation chemical synthesis  

SciTech Connect

The authors consider processes in radiation chemical synthesis which are being developed in various scientific-research organizations. The important advantages of radiation chlorination, viz. the lower temperature compared with the thermal method and the absence of dehydrochlorination products are discussed. The authors examine the liquid-phase chlorination of trifluorochloroethyltrichloromethyl ether to obtain the pentachloro-contining ether, trifluorodichloroethyltrichloromethyl ether. The authors discuss radiation synthesis processes that have be used formulated kinetic equations on which models have been based. It is concluded that the possibilities of preparative (micro- and low-tonnage) radiation synthesis are promising.

Zagoretz, P.A.; Poluetkov, V.A.; Shostenko, A.G.

1986-03-01

302

Radiation image inspection apparatus  

SciTech Connect

A radiation image inspection apparatus is described comprising: means for generating and directing radiation toward an article to be inspected; a screen for converting a radiation pattern of the article into a first visible light image; lens means for maintaining the intensity of a first visible light image produced on the screen; camera means having an image tube target and producing an electrical output system corresponding to the incident image on the image tube target from the lens means; and control means for controlling the operation of a camera means and the radiation generating means.

Velasquez, J.F.

1988-04-05

303

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

304

Spontaneous radiation of a brownian nanoparticle  

NASA Astrophysics Data System (ADS)

It is shown that a charged Brownian nanoparticle (or an electron) similar to a two-level atom can generate spontaneous and induced radiation upon switching on an external field. The diffusion mechanism of charging nanoparticles is examined. The radiation process is a macroscopic quantum phenomenon, which can be used in synthetic biology, medicine, and other fields of science and engineering.

Lasukov, V. V.; Dybov, A. R.

2011-09-01

305

Radiation physics, biophysics, and radiation biology  

SciTech Connect

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

Hall, E.J.

1992-05-01

306

Coherent synchrotron radiation and radiative electron polarization  

NASA Astrophysics Data System (ADS)

The process of radiative electron polarization through the mechanism of coherent synchrotron radiation (CSR) has been considered in the semi-classical approach. The CSR process is characterized by increasing photon emission probability from each electron proportional to number of electrons in a bunch if the wavelength of the emitted photon is greater than the bunch length. Estimations for built-up polarization of the electron beam Pcoh and the self-polarization time Tcoh caused by CSR mechanism were obtained and the comparison with ones for incoherent synchrotron radiation was performed. Despite the low probability of spin-flip transitions a significant particle polarization can be achieved for comparatively low values of the Lorentz factor (? <= 100) due to the huge number of photons emitted by each electron.

Potylitsyn, A. P.

2010-11-01

307

Application of Computer Global Radiation for Areas of High Relief.  

National Technical Information Service (NTIS)

The variation over uneven terrain of the daily total of incident shortwave (global) radiation under cloudless conditions may be estimated by existing methods for calculating direct and diffuse solar radiation on a slope. A computer program for performing ...

J. T. Andrews L. D. Williams R. G. Barry

1971-01-01

308

Testing of two models for computing global solar radiation on tilted surfaces  

Microsoft Academic Search

Solar radiation data computerly measured at Amman, Jordan was used to verify the performance accuracy of two models for estimation of global radiation on tilted surfaces. The measurements used in this study were the daily totals of global radiation on a horizontal surface, diffuse radiation on a horizontal surface and global radiation on a 45° tilted surface. The measured radiation

Salem Nijmeh; Rustom Mamlook

2000-01-01

309

Radiation Therapy for Vaginal Cancer  

MedlinePLUS

... internal radiation with or without low doses of chemotherapy. Side effects of radiation therapy Radiation can destroy nearby healthy ... occur, but can be treated with medicines. These side effects tend to be worse when chemotherapy is given with radiation. Pelvic radiation can lead ...

310

Office of Radiation Programs Training Manual. Management of Radiation Accidents.  

National Technical Information Service (NTIS)

Contents: Radiation fundamentals; Radiation detection; Radiation protection; Sources of radioactivity; (Sealed sources, Sealed sources in medicine, Sealed sources in industry, Basin principles of nuclear reactors, Nuclear detonations and fallout); Radiati...

1970-01-01

311

Radiation turbulence interactions in pulverized coal flames: Chaotic map models of soot fluctuations in turbulent diffusion flames. Quarterly report, October 1995--December 1995  

SciTech Connect

In this paper, we introduce a methodology to characterize soot volume fraction fluctuations in turbulent diffusion flames via chaotic maps. The approach is based on the hypothesis that the fluctuations of properties in turbulent flames is deterministic in nature, rather than statistical. Out objective is to develop models to mimic these fluctuations. The models will be used eventually in comprehensive algorithms to study the true physics of turbulent flames and the interaction of turbulence with radiation. To this extent, we measured the time series of soot scattering coefficient in an ethylene diffusion flame from light scattering experiments. Following this, corresponding power spectra and delay maps were calculated. It was shown that if the data were averaged, the characteristics of the fluctuations were almost completely washed out. The psds from experiments were successfully modeled using a series of logistic maps.

McDonough, J.M.; Menguc, M.P.; Mukerji, S.; Swabb, S.; Manickavasagam, S.; Ghosal, S.

1995-12-31

312

Relativistic collapsing radiating stars  

NASA Astrophysics Data System (ADS)

A new class of exact solutions of Einstein's equations is proposed for a collapsing radiating spherically symmetric shear-free isotropic fluid undergoing radial heat flow. In remote past the solutions are static perfect fluid which then gradually starts evolving into radiating collapse. The interior solutions are matched with Vaidya exterior metric over the boundary.

Tewari, B. C.

2012-11-01

313

Earth radiation budgets  

Microsoft Academic Search

The annual and seasonal averaged earth atmosphere radiation budgets, derived from the most complete set of satellite observations available in late 1979, are presented. The budgets are derived using a composite of 48 monthly mean radiation budget maps. The annual, global average emitted infrared flux is 234 W\\/sq m, the planetary albedo is 0.30, and the net flux is zero

G. L. Stephens; G. G. Campbell; T. H. Vonder Haar

1981-01-01

314

The Planck Radiation Functions.  

ERIC Educational Resources Information Center

Blackbody radiation is used as an example to illustrate that oversimplification in teaching quantum ideas can result in later misunderstanding. Although textbooks give Planck's distribution function in terms of wavelength, there are actually 12 different radiation functions. Some of the more interesting ones are given and discussed. (JN)

Larsen, Russell D.

1985-01-01

315

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

316

The Pressure of Radiation  

Microsoft Academic Search

IN his letter of January 1 Prof. Callendar gives his reasons for doubting the formula for the pressure of radiation as it is usually accepted. He makes use of Boltzmann's proof of the fourth power law for the complete radiation, extends it to each separate frequency, and deduces that the energy in every frequency aught to be proportional to the

C. G. Darwin

1914-01-01

317

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.

Program, U. S.

318

Forecasting Radiation Fog  

NSDL National Science Digital Library

The goal of this training module is to help you increase your understanding of how radiation fog forms, grows, and dissipates. Such understanding, in turn, can help you more efficiently and accurately evaluate the ability of a given atmospheric environment to generate and/or maintain radiation fog.

Spangler, Tim

1999-04-08

319

Impulse radiating antennas  

Microsoft Academic Search

A number of applications require radiation of a short pulse of electromagnetic energy out to large distances. These applications include target discrimination in a cluttered environment (e.g., looking over the ocean), aircraft identification by taking a 'TDR' of its major scattering centers, and target location through foliage. The Impulse Radiating Antenna (IRA) has generated widespread interest for its ability to

Carl E. Baum; Everett G. Farr

1993-01-01

320

Plastic plasticizer and radiation  

Microsoft Academic Search

Examination concerning the possibilities of decomposition of ; plasticizers such as phthalic acid esters and phosphoric acid esters or toxicity ; reduction thereof by the radiation has been made. (1) Radiation effects: Sham ; polluted solution having various kinds of concentrations of said ester was ; irradiated with ⁶°Co gamma -ray to 0.3 Mrad\\/hr. The results show that ; with

Sunada

1973-01-01

321

Chronic Radiation Enteritis  

Microsoft Academic Search

Chronic radiation enteritis is an increasing problem, as more patients receive radiotherapy as part of their cancer therapy and as the long-term survival of these patients improves. This review addresses the causes, investigation, treatment and prevention of this disease. A review of published studies was carried out using a variety of search terms, including radiation enteritis, investigation, treatment and prevention.

V. S. Theis; R. Sripadam; V. Ramani; S. Lal

2010-01-01

322

Synchrotron Radiation II.  

ERIC Educational Resources Information Center

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

MOSAIC, 1978

1978-01-01

323

Electromagnetic radiation detector  

DOEpatents

An electromagnetic radiation detector including a collimating window, a cathode member having a photoelectric emissive material surface angularly disposed to said window whereby radiation is impinged thereon at acute angles, an anode, separated from the cathode member by an evacuated space, for collecting photoelectrons emitted from the emissive cathode surface, and a negatively biased, high transmissive grid disposed between the cathode member and anode.

Benson, Jay L. (Albuquerque, NM); Hansen, Gordon J. (Albuquerque, NM)

1976-01-01

324

Physics for Radiation Protection  

NASA Astrophysics Data System (ADS)

A practical guide to the basic physics that radiation protection professionals need A much-needed working resource for health physicists and other radiation protection professionals, this volume presents clear, thorough, up-to-date explanations of the basic physics necessary to address real-world problems in radiation protection. Designed for readers with limited as well as basic science backgrounds, Physics for Radiation Protection emphasizes applied concepts and carefully illustrates all topics through examples as well as practice problems. Physics for Radiation Protection draws substantially on current resource data available for health physics use, providing decay schemes and emission energies for approximately 100 of the most common radionuclides encountered by practitioners. Excerpts of the Chart of the Nuclides, activation cross sections, fission yields, fission-product chains, photon attenuation coefficients, and nuclear masses are also provided. Coverage includes: * The atom as an energy system * An overview of the major discoveries in radiation physics * Extensive discussion of radioactivity, including sources and materials * Nuclear interactions and processes of radiation dose * Calculational methods for radiation exposure, dose, and shielding * Nuclear fission and production of activation and fission products * Specialty topics ranging from nuclear criticality and applied statistics to X rays * Extensive and current resource data cross-referenced to standard compendiums * Extensive appendices and more than 400 figures

Martin, James E.

2000-06-01

325

Continuum radiation at Uranus  

Microsoft Academic Search

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 Uranian continuum radiation is

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

1990-01-01

326

Radiation biology of mosquitoes  

Microsoft Academic Search

There is currently renewed interest in assessing the feasibility of the sterile insect technique (SIT) to control African malaria vectors in designated areas. The SIT relies on the sterilization of males before mass release, with sterilization currently being achieved through the use of ionizing radiation. This paper reviews previous work on radiation sterilization of Anopheles mosquitoes. In general, the pupal

Michelle EH Helinski; Andrew G Parker; Bart GJ Knols

2009-01-01

327

RADIATION POLYMERIZATION DOSIMETRY  

Microsoft Academic Search

Quantitative studies of the high energy radiation photo sensitivity of ; certain liquid monomer-polymers have indicated a possible solution to the problem ; of high level dosimetry. Investigations of the relation between absorbed dose ; and factors which influence sensitivity have led to the development of a ; dependable system of radiation polymerization dosimetry. Changes in the ; composition of

F. E. Hoecker; I. W. Watkins; J. T. Han

1958-01-01

328

Personal radiation dosimeter  

Microsoft Academic Search

A radiation dosimeter is described comprising: at least a first capacitive ionization chamber adapted to gradually discharge in the presence of incident radiation; a voltage source; a load resistor coupled to the voltage source; a first switch means coupled to the load resistor and the voltage source to form a first in-series circuit comprising the voltage source, the load resistor

Terhune

1986-01-01

329

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

330

Radiofrequency and microwave radiation  

Microsoft Academic Search

This paper deals with the controversy and disagreement surrounding the issue of harm from radiofrequency (RF) and microwaves. The radiation standards adopted by different countries are quite divergent with the least strict standard for microwave exposure differing from the most strict by a factor of 100. Among the most powerful sources of RF and microwave radiation are radar systems used

Hileman

1982-01-01

331

Evaluation of hourly tilted surface radiation models  

SciTech Connect

This study investigates the performance of the isotropic and four anisotropic hourly tilted surface radiation models by using monthly average hourly utilizable energy as a standard of measure. Utilizable energy is the radiation above a specified threshold level. Differences between the utilizable energy measured and the utilizable energy predicted are observed for various surface slope/azimuth orientations and critical radiation levels. Normalized root mean square difference and normalized mean bias difference statistics are formed to quantify the ability of each model to estimate the utilizable energy on a tilted surface. The influence of horizontal diffuse radiation on tilted surface model performance is examined by comparing the predicted utilizable energy on a tilted surface using both measured horizontal diffuse and estimated horizontal diffuse found from diffuse fraction correlations. On an overall basis, the isotropic sky model showed the poorest performance and is not recommended for estimating the hourly radiation on a tilted surface. The anisotropic models have comparable performance to each other. There was no significant degradation of tilted surface model performance when the diffuse radiation is estimated from a diffuse fraction correlation rather than obtained from measurements.

Reindl, D.T.; Beckman, W.A.; Duffie, J.A. (Univ. of Wisconsin, Madison (USA))

1990-01-01

332

Significance of tumor size and radiation dose to local control in Stage I–III diffuse large cell lymphoma treated with CHOP-Bleo and radiation  

Microsoft Academic Search

Purpose: The purpose of this study was ti evaluate the possible effect of adjunctive involve field (IF) radiotherapy on long-term local control for patients with Ann Arbor Stage I–III diffuse large cell lymphoma (DLCL) who achieved a complete remission on a combined modality program which included cyclophosphamide, doxorubicin, vincristine, prednisone, and Bleomycin (CHOP-Belo).Methods and Materials: One hundred and ninety patients

Lillian M. Fuller; Matthew J. Krasin; William S. Velasquez; Pamela K. Allen; Peter McLaughlin; M. Alma Rodriguez; Fredrick B. Hagemeister; Forrest Swan; Fernando Cabanillas; Judy L. Palmer; James D. Cox

1995-01-01

333

Radiation Protection in Canada  

PubMed Central

The current status of radiation protection in Canada has been summarized in the present paper, the first of a three-part series. Particular emphasis has been placed on the role of the Radiation Protection Division of the Department of National Health and Welfare. Somatic and hereditary effects of radiation exposure are briefly discussed as a basis for an understanding of the radiation protection standards which have been developed at national and international levels. The rapid increase in use of radioactive materials and x-ray apparatus in medicine, industry and research, and the extensive atmosphere testing of nuclear weapons have led to the development of comprehensive radiation protection activities in Canada, especially in the Department of National Health and Welfare. Well-established lines of communication and liaison exist among the various agencies responsible for these activities. ImagesFig. 1

Bird, P. M.

1964-01-01

334

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

335

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

336

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

337

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.

Lindell, B.

1987-01-01

338

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

339

Radiation heat loss detector  

SciTech Connect

In a radiation heat loss detector, radiation from an extended surface area is detected with a sensor having a wide field of view closely matching that of an associated camera. By simultaneously photographing the surface area of interest and detecting the radiation from that same area, a clear record is provided for future use. A wide band radiation sensor is used. Compensation for environmental radiation is made by first viewing the environment with the sensor and holding the sensed signal and then subtracting that signal from the flux detected when the sensor faces the extended surface area. The date and time are also recorded on the photograph. A sonar device positioned on the camera provides a distance indication which, with a known field of view, allows for a determination of the total flux from the surface area, a determination of convective heat losses from the surface and a correction for atmospheric absorption of the radiant energy.

Pompei, F.

1982-08-10

340

Radiation resistance of radiation shield rubber.  

National Technical Information Service (NTIS)

The radiation shield rubber of ethylene-propylene copolymer (EPDM) and of chlorinated polyethylene (CM) mixed with a large amount of powder or foil lead were irradiated under vacuum or in oxygen atmosphere by Co-60 gamma rays for an evaluation of the radi...

A. Kasai N. Yamaguchi T. Watanabe T. Seguchi M. Nishii

1990-01-01

341

RADIATION BIOLOGY: CONCEPTS FOR RADIATION PROTECTION  

Microsoft Academic Search

The opportunity to write a historical review of the field of radiation biology allows for the viewing of the devel- opment and maturity of a field of study, thereby being able to provide the appropriate context for the earlier years of re- search and its findings. The pioneering work of Muller, Sax, and McClintock, and many others, has stood the

R. Julian Preston

2004-01-01

342

Radiation Therapy for Lung Cancer  

MedlinePLUS

... visit: National Cancer Institute www.cancer.gov/clinicaltrials Radiation Therapy Answers www.rtanswers.org STRO AMERICAN SOCIETY FOR ... of the lung cancer and your overall health. Radiation Therapy Radiation is a high-energy X-ray that ...

343

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 ...

344

Ground-reflected radiation and albedo  

SciTech Connect

The diffuse radiation incident on an inclined plane is composed of both the ground-reflected radiation and the sky diffuse radiation. The evaluation of the sky diffuse radiation has already been described in many references. In this paper they focus on the ground-reflected radiation, its relation to insolation conditions and its evaluation by means of models. The authors used six data banks from the following four countries: Switzerland, France, The Netherlands, and the US. The authors investigated how the albedo depends on the amount and the composition of the incident radiation, on geometrical parameters such as the height and/or the azimuth of the sun and on meteorological parameters such as the humidity. They did not find any notable dependence. They also tested different models evaluating the ground-reflected radiation on tilted planes with corresponding measurements on an inverse horizontal plane (facing the ground) and on inclined planes. They came to the conservative conclusion that the best results are obtained when using a constant averaged measured albedo, for transposition to tilted surfaces, when assuming the ground-reflected radiation to be isotropic.

Ineichen, P.; Guisan, O.; Perez, R. (Univ. of Geneva (Switzerland) Atmospheric Science Research Center, Albany, NY (USA))

1990-01-01

345

The RAGE radiation-hydrodynamic code  

NASA Astrophysics Data System (ADS)

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

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

2008-10-01

346

Synchrotron radiation sources and research  

SciTech Connect

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

Teng, L.C.

1995-12-31

347

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.

Kim, Kwanghee; McBride, William H.

2011-01-01

348

Microenvironment and Radiation Therapy  

PubMed Central

Dependency on tumor oxygenation is one of the major features of radiation therapy and this has led many radiation biologists and oncologists to focus on tumor hypoxia. The first approach to overcome tumor hypoxia was to improve tumor oxygenation by increasing oxygen delivery and a subsequent approach was the use of radiosensitizers in combination with radiation therapy. Clinical use of some of these approaches was promising, but they are not widely used due to several limitations. Hypoxia-inducible factor 1 (HIF-1) is a transcription factor that is activated by hypoxia and induces the expression of various genes related to the adaptation of cellular metabolism to hypoxia, invasion and metastasis of cancer cells and angiogenesis, and so forth. HIF-1 is a potent target to enhance the therapeutic effects of radiation therapy. Another approach is antiangiogenic therapy. The combination with radiation therapy is promising, but several factors including surrogate markers, timing and duration, and so forth have to be optimized before introducing it into clinics. In this review, we examined how the tumor microenvironment influences the effects of radiation and how we can enhance the antitumor effects of radiation therapy by modifying the tumor microenvironment.

Yoshimura, Michio; Itasaka, Satoshi; Harada, Hiroshi; Hiraoka, Masahiro

2013-01-01

349

Beneficial uses of radiation  

SciTech Connect

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

Fox, M.R.

1991-10-01

350

Modifying radiation damage.  

PubMed

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

2010-11-01

351

SYNCHROTRON RADIATION SOURCES  

SciTech Connect

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

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

1998-07-01

352

Radiation Damage Theory  

SciTech Connect

This chapter presents an overview of basic radiation damage theory, including older and more recent models, to provide framework, within which radiation effects, such as void swelling, can be rationalized. A complete review of the literature is not attempted, but sufficient references are given to provide a decent introduction to a quite large number of publications in the field. Many derivations are different from and, in our view, more elegant than in the original publications. The work is directed to both theoreticians and experimentalists, and, especially, to those passionate individuals who are going to take the radiation damage theory (RDT) to the future.

Golubov, Stanislav I [ORNL; Barashev, Aleksandr [University of Liverpool; Stoller, Roger E [ORNL

2012-01-01

353

METHOD FOR MEASURING RADIATION  

DOEpatents

A method for measuring an unknown integrated quantity of radiation with a condenser ionization chamber is described. The chamber is initially charged to a predetermined voltage by a voltage source. The chamber is then removed from the source and exposed to an unknown quantity of radiation for a period of time. The quantity of radiation to which the chamber was exposed is then measured by detecting the magnitude of the pulse of current necessary to recharge the chamber of its initial value through a suitable impedance. The current pulse is amplified and measured directly by a suitable pulse height analyzing system. (AEC)

Roesch, W.C.; McCall, R.C.

1961-11-21

354

Absolute radiation detector  

NASA Astrophysics Data System (ADS)

An absolute radiation detector (a cryogenic radiometer) is being developed to replace the existing UK primary national standard cryogenic radiometer with an improved uncertainty. The cryogenic radiometer will be capable of measuring black body radiation and laser radiation with an uncertainty approaching 10 ppm. From these measurements it will be possible to determine the fundamental constant, the Stefan Boltzmann constant, confirming the radiometer as an absolute detector, and link this determination to the SI unit of luminous intensity, the candela. Thus detector and source based scales/standards will be tied to an invariant physical quantity ensuring their long-term stability.

Martin, John E.

1996-11-01

355

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

356

Radiation degradation of polymethacrylamide  

SciTech Connect

The effects of radiation on polymers have been studied for many years. When polymers are subjected to ultraviolet light or ionizing radiation, chain scission and crosslinking are possible. The radiation degradations of several methacrylate type polymers were investigated. The primary polymer studied was polymethacrylamide (PMAAm). Ultraviolet irradiated PMAAm yielded a five line ESR spectrum with 22 gauss splitting which is believed to arise from a polymeric radical ending with a methacrylamide unit. The results obtained indicate that polymethacrylamide is a polymer which undergoes main chain cleavage upon irradiation. As such this polymer may have potential applicability as a positive resist for fabrication of microelectronic devices.

O'Connor, D.J.

1984-01-01

357

Fast multilevel radiative transfer  

NASA Astrophysics Data System (ADS)

The vast majority of recent advances in the field of numerical radiative transfer relies on approximate operator methods better known in astrophysics as Accelerated Lambda-Iteration (ALI). A superior class of iterative schemes, in term of rates of convergence, such as Gauss-Seidel and Successive Overrelaxation methods were therefore quite naturally introduced in the field of radiative transfer by Trujillo Bueno & Fabiani Bendicho (1995); it was thoroughly described for the non-LTE two-level atom case. We describe hereafter in details how such methods can be generalized when dealing with non-LTE unpolarised radiation transfer with multilevel atomic models, in monodimensional geometry.

Paletou, Frédéric; Léger, Ludovick

2007-01-01

358

Clouds and Solar Radiation  

NSDL National Science Digital Library

Most people are aware that clouds impact the amount of solar energy that is received at the ground. This lesson examines qualitative and quantitative aspects of how clouds affect incoming solar radiation. Students will be given a visible satellite image, and asked to describe where clouds are located in the state. Given a map of Mesonet solar radiation measurements, the students will be asked to determine regions of relatively high and low values of solar radiation. This lesson also enables students to practice analyzing different types of data sets and compare patterns between two types of data.

359

Blackbody Radiation Spectrum Model  

NSDL National Science Digital Library

The Blackbody Radiation Spectrum model shows six fixed-temperature curves between Tmin and Tmax and a red variable-temperature curve that can be adjusted using a slider. The wavelength is measured in nm (nanometer) and the intensity is measured in W.e-5 / (m2.nm). Users can adjust Tmin and Tmax to change the temperature range that is displayed. The Blackbody Radiation Spectrum was created using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double click the ejs_ntnu_BlackbodyRadiationSpectrum.jar file to run the program if Java is installed.

Hwang, Fu-Kwun

2009-08-22

360

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

361

Radiation and Health  

NASA Astrophysics Data System (ADS)

This is a shortened version of the Science Teachers' Workshop offered free of charge to primary and secondary teachers at a location of their choice, covering fundamentals of nuclear radiation, natural and man-made sources of radiation, biological effects and risks to health, radioactive waste management, and radiation safety management and regulation. The course includes a hands-on demonstration of use of Geiger Counters, which are given without cost to participants for use in their classes. A CD and notebook of class material are issued to each student. Lunch will be provided. Limited to 20 participants.

Evans, Albert E.

2008-03-01

362

Radiation and Health  

NASA Astrophysics Data System (ADS)

This is a shortened version of the Science Teachers' Workshop offered free of charge to primary and secondary teachers at a location of their choice, covering fundamentals of nuclear radiation, natural and man-made sources of radiation, biological effects and risks to health, radioactive waste management, and radiation safety management and regulation. The course includes a hands-on demonstration of use of Geiger Counters, which are given without cost to participants for use in their classes. A CD and notebook of class material are issued to each student. Lunch will be provided.

Evans, Albert; Blanchard, Karen

2007-10-01

363

On the Long-Term Variation of Galactic Cosmic Rays: Convection-Diffusion and Drift Modulations in the Heliosphere, Expected Radiation Hazard  

NASA Astrophysics Data System (ADS)

On the basis of results obtained in our investigations of CR-SA hysteresis effects we determine the dimension of Heliosphere (modulation region), radial diffusion coefficient and other param-eters of convection-diffusion and drift mechanisms of cosmic ray (CR) long term variation in dependence of particles energy, level of solar activity (SA) and general solar magnetic field. This important information we obtain on the basis of CR and SA data in the past taking into account the theory of convection-diffusion and drift global modulation of galactic CR in the Heliosphere. By using these results and published regularly elsewhere predictions of expected sunspot number variation in near future and prediction of future next SA cycle we may made prediction of expected in near future (up to 10-12 years) long-term CR intensity variation. From other hand, we use estimated properties of connection between CR intensity long-term variation and some part of global climate change, controlled by solar activity through CR. We show that by this way we may made prediction of expected in near future (up to 10-12 years) radiation hazard from galactic CR in interplanetary space at different distances from the Sun (what is important for space probes and long-term missions to Mars and other planets and their satellites) and long-living objects on different orbits in the Earth's magnetosphere, as well as in the Earth's atmosphere (e.g. for airplanes at altitude about 10 km). Let us underline that in the last two cases become important to take into account also expected long-term changes in the planetary distribution of cutoff rigidities, which also influenced on observed galactic CR intensity, and corresponding radiation hazard.

Dorman, Lev

364

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

365

Effect of radiation dose on radiation creep of polymers  

Microsoft Academic Search

In investigations of radiation creep and service life of polymers the question arises: Are these radiation effects not determined by increasing doses of ionizing radiation? The effect of a radiation dose may be manifested, in particular, in rupture of the chemical bonds responsible for the strength of the polymer, as loading might cause supplemental deformation; and, when irradiation takes place

V. F. Stepanov; S. É. Vaisberg; V. L. Karpov

1974-01-01

366

The topographic variability of solar radiation  

NASA Astrophysics Data System (ADS)

This research explores the spatial and temporal variability of incoming and net solar radiation over different topographic regions and examines the atmospheric and terrain parameters that control this variability. A twostream radiative transfer algorithm is used with digital elevation data and atmospheric optical properties to model the detailed interaction of incoming direct and diffuse solar irradiance with a reflective topographic surface. The mean, variance, and spatial autocorrelation in incoming solar radiation are compared for different regions, including the Konza Prairie, home of the First International Satellite Land Surface Climatology Project (ISLSCP) Field Experiment (FIFE). A simplified radiation model is used to identify the physical factors controlling differences in radiation regimes among terrain. Topography does not significantly affect the regional mean calculated over 10 x 10 sq km areas, except for the most rugged terrain. Average spatial autocorrelation in incoming radiation varies from 200 to 1200 m depending on the terrain. The radiation model is also used with LANDSAT Thematic Mapper data and digital elevation data to estimate net solar radiation across the FIFE site. Model estimates are in excellent agreement with field pyranometer measurements. Topography is the most important factor controlling the spatial variability of net solar radiation for the site. Variability in reflectance is of secondary importance. If the effects of topography on satellite reflectance and incoming irradiance are ignored, the resulting map of apparent net solar radiation shows little spatial variability and poor correlation with field measurements.

Dubayah, Ralph O.

367

Radiation Exposure and Cancer  

MedlinePLUS

... such actions are warranted, according to the NIEHS. Television and computer screens Modern television and computer screens give off several kinds of ... waves) Radiofrequency radiation is emitted from radio and television broadcast transmitters, citizen band radios, and electric heaters. ...

368

External Radiation Therapy  

MedlinePLUS Videos and Cool Tools

... mark where the differences between success rates with radical prostatectomy and radiation therapy become evident,and if you' ... to put you through a major operation like radical prostatectomy, and in those situations, I do refer patients ...

369

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

370

Management of radiation wounds  

SciTech Connect

Radiation wounds caused by newer high-voltage radiotherapy techniques are very difficult to manage. Recent developments in flap design and transfer aid the surgeon in successfully treating these difficult problems.

Reinisch, J.F.; Puckett, C.L.

1984-08-01

371

Hyperphysics: Blackbody Radiation  

NSDL National Science Digital Library

This Hyperphysics site gives a thorough explanation of "Blackbody" or "cavity" radiation, offering examples on both the classical and quantum level. A number of diagrams and example plots are used to aid in the description.

Nave, Carl R.

2008-07-18

372

Radiation Hardened Field Oxide.  

National Technical Information Service (NTIS)

This paper describes the development of a radiation-tolerant field oxide compatible with both MOS and bipolar technologies. Data is presented which illustrates that nonguardbanded devices utilizing conventional field oxide structures cannot be expected to...

J. R. Adams W. R. Dawes T. J. Sanders

1977-01-01

373

Radiation Technology, Issue 6.  

National Technical Information Service (NTIS)

The publication deals with theoretical and experimental works on the nuclear-physical basis of radiation technology, isotope thermoelectric generators, equipment irradiation, pulse proton generator, nuclear methods of analysis, gamma flaw detection, radio...

1971-01-01

374

Synchrotron Radiation Sources  

ScienceCinema

The fundamental basis of synchrotron radiation will be presented in an easy to follow historically based perspective. The development of modern high brightness sources will be illustrated and a view given of the potential for coherent sources in the future.

375

[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

376

IMPULSE RADIATING ANTENNAS  

Microsoft Academic Search

A number of applications require radiation of a short pulse of electromagnetic energy out to large distances. These applications include target discrimination in a cluttered environment (e.g., looking over the ocean), aircraft identification by taking a \\

Carl E. Baum; Everett G. Farr; Kirtland AFB

377

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

378

John Tyndall's Radiation Experiment  

Microsoft Academic Search

IN the recently published ``Life and Work of John Tyndall'' no alteration has been made in his explanation of his experiment on radiation through a solution of iodine in carbon disulphide, rendering platinized platinum foil white hot.

T. H. Muras

1946-01-01

379

Calculate Your Radiation Dose  

MedlinePLUS

... Do you live within 50 miles of a nuclear power plant? Do you live within 50 miles of a coal fired power plant? TOTAL YEARLY DOSE (in mrem) ... the American Nuclear Society's brochure, "Personal Radiation Dose Chart". The primary ...

380

Radiation and Society  

ERIC Educational Resources Information Center

Presents a discussion of the risks, to society, from radiation-associated technologies and urges that science teachers help the public understand the decision-making process relative to nuclear power as well as the problems and alternatives. (PEB)

Shaw, Edward I.

1974-01-01

381

Tin Can Radiation Detector.  

ERIC Educational Resources Information Center

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

Crull, John L.

1986-01-01

382

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

383

Solar Cell Radiation Handbook.  

National Technical Information Service (NTIS)

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 c...

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

1982-01-01

384

Isotopes and radiation  

SciTech Connect

Subjects covered in this section are: (1) Food industry groups petition for expanded use of irradiation; (2) First meeting of BEIR VII committee with new members held; and (3) DOE undertaking 10-yr study of radiation health effects.

NONE

1999-10-01

385

Stellar Blackbody Radiation Curves  

NSDL National Science Digital Library

Stellar Blackbody Radiation Curves model simulates the blackbody radiation curve of stars and how this leads to the observed color and luminosity of the star. If a star can be treated as a blackbody, the blackbody radiation curve of the star, the power density per area (or intensity) per wavelength (energy/time/volume) vs wavelength, is dependent on the star's temperature (spectral class). In the simulation, the star is shown along with its luminosity and spectral class. In separate graph, the blackbody radiation curve, the visible part of the spectrum, and the integrated stellar surface intensity (integrating the blackbody curve over all wavelengths) are shown. In another window the HR diagram can be shown indicating the current star's parameters. The radius of the star (in Rsun) and the temperature of the star in Kelvin (5780 K is Tsun) can be changed.

Belloni, Mario

2010-11-11

386

Ionizing radiation detector  

DOEpatents

An ionizing radiation detector is provided which is based on the principal 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, L.H.

1989-06-08

387

SOLAR RADIATION, VA  

EPA Science Inventory

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

388

Acute radiation syndrome caused by accidental radiation exposure - therapeutic principles  

PubMed Central

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

2011-01-01

389

Radiation hard fiber optics  

Microsoft Academic Search

A study of radiation-inducted absorption in low-loss optical waveguides is reported. Step-index optical fibers were prepared from preforms fabricated by the CVD method. The germanium silicate core glass in the fibers was doped with varying amounts of antimony, cerium, boron, phosphorus and hydroxyl groups. The effects of such variations in the glass chemistry on the radiation inducted attenuation of the

R. E. Jaeger; M. Aslami

1981-01-01

390

Pelvic Radiation in Women  

Microsoft Academic Search

\\u000a Pelvic radiation represents a major therapeutic strategy, either as adjuvant or primary treatment in the management of cancer\\u000a in women. This mainly concerns women with gynaecological malignancies: endometrial, cervical, vaginal, and vulva cancer; intestinal\\u000a malignancies: rectal and anal cancer, and bladder cancer. Further, long-term breast cancer survivors may experience similar\\u000a adverse effects after ovarian ablation accomplished by pelvic radiation. Finally,

Pernille T. Jensen

391

Radiative Transitions in Charmonium  

SciTech Connect

The form factors for the radiative transitions between charmonium mesons are investigated. We employ an anisotropic lattice using a Wilson gauge action, and domain-wall fermion action. We extrapolate the form factors to Q{sup 2} = 0, corresponding to a real photon, using quark-model-inspired functions. Finally, comparison is made with photocouplings extracted from the measured radiative widths, where known. Our preliminary results find photocouplings commensurate with these experimentally extracted values.

Jozef Dudek; Robert Edwards; David Richards

2005-10-01

392

Nanocomposites for radiation sensing  

NASA Astrophysics Data System (ADS)

The use of light emitting nanoparticles in polymer and glass matrices was studied for the detection of radiation. These nanocomposite scintillators were produced by various approaches including quantum dot/polymer, fluoride nanophosphor/epoxy and halide nanophosphor containing glass-ceramic composites. The synthesis and characterization of these nanoparticles as well as their incorporation into composites is discussed. Further, the application of these composites for radiation detection and spectroscopy is described.

Wagner, Brent K.; Kang, Zhitao; Nadler, Jason; Rosson, Robert; Kahn, Bernd

2012-05-01

393

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.

394

Net Radiation and Temperature  

NSDL National Science Digital Library

In this activity, students analyze actual net radiation data from their professor's field site in Northern Manitoba, Canada. They use this data to assess when the site has a radiation surplus and when it has a deficit. They use this data to estimate the time of the temperature minimum. They then think about what they've learned about seasonal cycles in insolation to predict how these patterns would shift at a different time of year.

Dunn, Allison

395

Smart radiation sensor management  

Microsoft Academic Search

We developed two radiation mapping algorithms that can handle different situations based on prior information of the search area. The algorithms were developed in the framework of model-driven measurement, where a world model was used to drive measurement collection, and measurements were used to update the world model.We developed and experimentally tested a robotic implementation of two Bayesian-based radiation mapping

R. ANDRES CORTEZ; Xanthi Papageorgiou; HERBERT G. TANNER; ALEXEI V. KLIMENKO; KONSTANTIN N. BOROZDIN; Ron Lumia; WILLIAM C. PRIEDHORSKY

2008-01-01

396

Automated personnel radiation monitor  

Microsoft Academic Search

An automated Personnel Low-Level Radiation Portal Monitor has been developed by UNC Nuclear Industries, Inc. It is micro-computer controlled and uses nineteen large gas flow radiation detectors. By employing a micro-computer, sophisticated mathematical analysis is used on the detector informational data base to determine the statistical probability of contamination. This system provides for: (1) Increased sensitivity to point source contamination;

1981-01-01

397

Gene Therapy and Radiation  

Microsoft Academic Search

\\u000a Owing to a low efficiency of gene transfer when delivered systemically, gene therapy may find its greatest utility in the\\u000a clinic when combined with loco-regional cancer treatment such as radiation therapy. Although a variety of gene therapy strategies\\u000a have been combined with radiation in preclinical models, only a handful have been translated into the clinic. Overall, combining\\u000a gene therapy with

Svend O. Freytag; Kenneth N. Barton; Farzan Siddiqui; Mohamed Elshaikh; Hans Stricker; Benjamin Movsas

398

ISO radiation sterilization standards  

NASA Astrophysics Data System (ADS)

This presentation provides an overview of the current status of the ISO radiation sterilization standards. The ISO standards are voluntary standards which detail both the validation and routine control of the sterilization process. ISO 11137 was approved in 1994 and published in 1995. When reviewing the standard you will note that less than 20% of the standard is devoted to requirements and the remainder is guidance on how to comply with the requirements. Future standards developments in radiation sterilization are being focused on providing additional guidance. The guidance that is currently provided in informative annexes of ISO 11137 includes: device/packaging materials, dose setting methods, and dosimeters and dose measurement, currently, there are four Technical Reports being developed to provide additional guidance: 1. AAMI Draft TIR, ``Radiation Sterilization Material Qualification'' 2. ISO TR 13409-1996, ``Sterilization of health care products - Radiation sterilization - Substantiation of 25 kGy as a sterilization dose for small or infrequent production batches'' 3. ISO Draft TR, ``Sterilization of health care products - Radiation sterilization Selection of a sterilization dose for a single production batch'' 4. ISO Draft TR, ``Sterilization of health care products - Radiation sterilization-Product Families, Plans for Sampling and Frequency of Dose Audits.''

Lambert, Byron J.; Hansen, Joyce M.

1998-06-01

399

Radiation disasters and children.  

PubMed

The special medical needs of children make it essential that pediatricians be prepared for radiation disasters, including 1) the detonation of a nuclear weapon; 2) a nuclear power plant event that unleashes a radioactive cloud; and 3) the dispersal of radionuclides by conventional explosive or the crash of a transport vehicle. Any of these events could occur unintentionally or as an act of terrorism. Nuclear facilities (eg, power plants, fuel processing centers, and food irradiation facilities) are often located in highly populated areas, and as they age, the risk of mechanical failure increases. The short- and long-term consequences of a radiation disaster are significantly greater in children for several reasons. First, children have a disproportionately higher minute ventilation, leading to greater internal exposure to radioactive gases. Children have a significantly greater risk of developing cancer even when they are exposed to radiation in utero. Finally, children and the parents of young children are more likely than are adults to develop enduring psychologic injury after a radiation disaster. The pediatrician has a critical role in planning for radiation disasters. For example, potassium iodide is of proven value for thyroid protection but must be given before or soon after exposure to radioiodines, requiring its placement in homes, schools, and child care centers. Pediatricians should work with public health authorities to ensure that children receive full consideration in local planning for a radiation disaster. PMID:12777572

2003-06-01

400

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

401

Bile Duct (Cholangiocarcinoma) Cancer: Radiation Therapy  

MedlinePLUS

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

402

Simulation of solar radiation during a total eclipse: a challenge for radiative transfer  

NASA Astrophysics Data System (ADS)

A solar eclipse is a rare but spectacular natural phenomenon and furthermore it is a challenge for radiative transfer modelling. Whereas a simple one-dimensional radiative transfer model with reduced solar irradiance at the top of the atmosphere can be used to calculate the brightness during partial eclipses a much more sophisticated model is required to calculate the brightness (i.e. the diffuse radiation) during the total eclipse. The reason is that radiation reaching a detector in the shadow gets there exclusively by horizontal transport of photons in a spherical shell atmosphere, which requires a three-dimensional radiative transfer model. In this study the first fully three-dimensional simulations for a solar eclipse are presented exemplified by the solar eclipse at 29 March 2006. Using a backward Monte Carlo model we calculated the diffuse radiation in the umbra and simulated the changing colours of the sky. Radiance and irradiance are decreased by 3 to 4 orders of magnitude, depending on wavelength. We found that aerosol has a comparatively small impact on the radiation in the umbra. We also estimated the contribution of the solar corona to the radiation under the umbra and found that it is negligible compared to the diffuse solar radiation in the wavelength region from 310 to 500 nm.

Emde, C.; Mayer, B.

2007-05-01

403

Unintentional radiation from shielded transformers  

Microsoft Academic Search

It is shown experimentally that a typical shielded broadband transformer intended for bulk current injection measurements radiates far-field electromagnetic energy. This radiation occurs in spite of the shield and is distinct from any radiation due to common mode currents on the exterior of the coaxial feed transmission line. The radiation patterns presented here taken together with previous results which showed

James McLean; Robert Sutton

2010-01-01

404

Radiation Therapy for Skin Cancer  

MedlinePLUS

... melanoma.org Skin Cancer Foundation www.skincancer.org Radiation Therapy Answers www.rtanswers.org AMERICAN SOCIETY FOR RADIATION ... visit: National Cancer Institute www.cancer.gov/clinicaltrials Radiation Therapy Answers www.rtanswers.org Radiation Therapy Oncology Group ...

405

Health effects of ionizing radiation  

SciTech Connect

Although humans have evolved in an environment of ionizing radiation, it was not until man-made sources were developed that the effects of ionizing radiation started to become known. Detection and measurement of radiation is not only sophisticated but widely applied. This article deals with exposure to this kind of radiation and the risk it may cause.

Fry, R.J.; Fry, S.A. (Oak Ridge National Laboratory, TN (USA))

1990-03-01

406

Interaction of Radiation with Matter  

SciTech Connect

A flash introductory course in the interaction of ionizing radiation with matter is presented for students starting out in nuclear physics, medical applications of radiation, materials modification, radiation damage, detectors, materials analysis, radiation protection, and other applications. Emphasis is on defining basic concepts and on a simple visualization of ideas for practical applications, rather than on completeness or rigor.

Rickards, J. [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, Apartado Postal 20-364, Mexico, D.F., 01000 (Mexico)

2010-09-10

407

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

408

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.

2002-01-01

409

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.

2007-05-15

410

Radiation by relativistic dipoles. III  

Microsoft Academic Search

The classical radiation of a point magnetic moment (a magneton) moving at a constant velocity in an arbitrary direction with respect to the field lines of a uniform magnetic field is analyzed. All characteristics of the radiation agree with the Ternov-Bagrov-Khapaev relativistic quantum thoery of the radiation by a neutron. It is thus demonstrated that the classical model of radiation

V. A. Bordovitsyn; V. S. Gushchina

1994-01-01

411

Radiation nephritis causing nephrotic syndrome  

SciTech Connect

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

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

1983-12-01

412

Radiative heat transfer in plastic welding process  

NASA Astrophysics Data System (ADS)

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

Kurosaki, Yasuo

2005-06-01

413

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

NASA Astrophysics Data System (ADS)

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

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

2012-07-01

414

Pretreatment Prediction of Brain Tumors' Response to Radiation Therapy Using High b Value Diffusion-Weighted MRI  

Microsoft Academic Search

Diffusion-weighted magnetic resonance imaging (DWMRI) is sensitive to tissues' biophysical character- istics, including apparent diffusion coefficients (ADCs) and volume fractions of water in different populations. In this work, we evaluate the clinical efficacy of DWMRI and high diffusion-weighted magnetic resonance imaging (HDWMRI), acquired up to b = 4000 sec\\/mm2 to amplify sensitivity to water diffusion properties, in pretreatment prediction of

Yael Mardor; Yiftach Roth; Aharon Ocherashvilli; Roberto Spiegelmann; Thomas Tichlerb; Dianne Daniels; Stephan E. Maier; Ouzi Nissim; Zvi Ram; Jacob Baram; Arie Orenstein; Raphael Pfeffer

2004-01-01

415

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

416

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.

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

2013-01-01

417

METSTAT—The solar radiation model used in the production of the National Solar Radiation Data Base (NSRDB)  

Microsoft Academic Search

This paper describes selectee aspects of the METSTAT (Meteorological\\/Statistical) solar radiation model. METSTAT was developed specifically to support the production of the National Solar Radiation Data Base for the United States. The model was used to estimate hourly values of direct normal, diffuse horizontal, and global horizontal solar radiation for those times and locations for which measured data were not

E. L. Maxwell

1998-01-01

418

Pretreatment prediction of brain tumors' response to radiation therapy using high b-value diffusion-weighted MRI.  

PubMed

Diffusion-weighted magnetic resonance imaging (DWMRI) is sensitive to tissues' biophysical characteristics, including apparent diffusion coefficients (ADCs) and volume fractions of water in different populations. In this work, we evaluate the clinical efficacy of DWMRI and high diffusion-weighted magnetic resonance imaging (HDWMRI), acquired up to b = 4000 sec/mm(2) to amplify sensitivity to water diffusion properties, in pretreatment prediction of brain tumors' response to radiotherapy. Twelve patients with 20 brain lesions were studied. Six ring-enhancing lesions were excluded due to their distinct diffusion characteristics. Conventional and DWMRI were acquired on a 0.5-T MRI. Response to therapy was determined from relative changes in tumor volumes calculated from contrast-enhanced T1-weighted MRI, acquired before and a mean of 46 days after beginning therapy. ADCs and a diffusion index, R(D), reflecting tissue viability based on water diffusion were calculated from DWMRIs. Pretreatment values of ADC and R(D) were found to correlate significantly with later tumor response/nonresponse (r = 0.76, P <.002 and r = 0.77, P <.001). This correlation implies that tumors with low pretreatment diffusion values, indicating high viability, will respond better to radiotherapy than tumors with high diffusion values, indicating necrosis. These results demonstrate the feasibility of using DWMRI for pretreatment prediction of response to therapy in patients with brain tumors undergoing radiotherapy. PMID:15140402

Mardor, Yael; Roth, Yiftach; Ochershvilli, Aharon; Spiegelmann, Roberto; Tichler, Thomas; Daniels, Dianne; Maier, Stephan E; Nissim, Ouzi; Ram, Zvi; Baram, Jacob; Orenstein, Arie; Pfeffer, Raphael

419

Radiation Protection in Canada  

PubMed Central

The current status of radiation protection in Canada is discussed in the last of a three-part series. Particular emphasis has been placed on the role of the Radiation Protection Division of the Department of National Health and Welfare. A radioactive fallout study program has been established involving the systematic collection of air and precipitation samples from 24 locations, soil samples from 23 locations, fresh-milk samples from 16 locations, wheat samples from nine areas and human-bone specimens from various hospitals throughout Canada. A whole-body-counting facility and a special study of fallout in Northern areas have also been initiated. For any age group, the highest average strontium-90 concentration in human bone so far reported has been less than four picocuries per gram of calcium compared with the maximum permissible level of 67 derived from the International Committee on Radiation Protection (ICRP) recommendations. By the end of 1963 a general downward trend of levels of radioactivity detected in other parts of the program has been observed. Programs to assess the contribution to the radiation exposure of members of the population from medical x-rays, nuclear reactor operations and natural background-radiation sources have also been described. The annual genetically significant dose from diagnostic x-ray examinations in Canadian public hospitals has been estimated to be 25.8 mrem. Results from the reactor-environment monitoring programs have not suggested the presence of radioactivity beyond that contributed from fallout.

Bird, P. M.

1964-01-01

420

Reducing Radiation Damage  

ScienceCinema

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.

421

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

422

AREA RADIATION MONITOR  

DOEpatents

S>An improved area radiation dose monitor is designed which is adapted to compensate continuously for background radiation below a threshold dose rate and to give warning when the dose integral of the dose rate of an above-threshold radiation excursion exceeds a selected value. This is accomplished by providing means for continuously charging an ionization chamber. The chamber provides a first current proportional to the incident radiation dose rate. Means are provided for generating a second current including means for nulling out the first current with the second current at all values of the first current corresponding to dose rates below a selected threshold dose rate value. The second current has a maximum value corresponding to that of the first current at the threshold dose rate. The excess of the first current over the second current, which occurs above the threshold, is integrated and an alarm is given at a selected integrated value of the excess corresponding to a selected radiation dose. (AEC)

Manning, F.W.; Groothuis, S.E.; Lykins, J.H.; Papke, D.M.

1962-06-12

423

Stereotactic body radiation therapy.  

PubMed

Stereotactic body radiation therapy constitutes an emerging therapeutic paradigm. These treatments are unique relative to the large body of experience with conventional fractionated radiotherapy. On the basis of the treatment principles of intracranial stereotactic radiation combined with enhancements associated with immobilization and imaging, the role of extracranial treatment continues to evolve. However, most clinical reports on extracranial treatments suffer from short or incomplete follow-up, making final assessments of benefit and toxicity, particularly late toxicity, problematic. These techniques are centered on a very basic understanding of the use of ionizing radiation for the treatment of cancer. Nonetheless, they do require a unique and special understanding of radiobiologic and physics principles. It is hoped that using high-dose, single-fraction treatment or a few fractions of treatment, the therapeutic ratio is improved, thus potentially changing the way some cancers are treated. Ideally, all patients receiving such treatments would be enrolled in formal protocols. As data accrue and understanding of these techniques improve, it will be possible to better define the indications for stereotactic body radiation therapy. At that time, appropriate applications can be submitted for permanent billing codes that will describe a process of care that embraces this technology without vendor favoritism. This review summarizes the state of stereotactic body radiation in 2005. PMID:17411904

Potters, Louis; Timmerman, Robert; Larson, David

2005-08-01

424

Radiation and resistance of tubers to rot  

Microsoft Academic Search

Conclusions  Sprout-inhibiting doses of ionizing radiation do not increase resistance to infection of wounds by bacteria.\\u000a \\u000a Diffusion of nutrients from wounds, periderm formation, and maceration are processes important in the initiation and development\\u000a of rot. Only periderm formation was affected by radiation in our experiments. Periderm formation is noticeably inhibited at\\u000a doses at, or just above, those suggested for sprout inhibition.

Paul E. Waggoner

1955-01-01

425

Radiation measurements for solar energy applications  

Microsoft Academic Search

The results of radiation measurements made over the tropics and the arid and semi-arid subtropics of the world using ground based and satellite borne sensors are summarized. It is shown that solar energy of the order of 7 kWh\\/sq m is received daily at stations in the arid regions, with durations of sunshine exceeding 3,600 hours a year. Diffuse radiation

A. Mani

1977-01-01

426

Simulation of solar radiation during a total solar eclipse: a challenge for radiative transfer  

NASA Astrophysics Data System (ADS)

A solar eclipse is a rare but spectacular natural phenomenon and furthermore it is a challenge for radiative transfer modeling. Whereas a simple one-dimensional radiative transfer model with reduced solar irradiance at the top of the atmosphere can be used to calculate the brightness during partial eclipses a much more sophisticated model is required to calculate the brightness (i.e. the diffuse radiation) during the total eclipse. The reason is that radiation reaching a detector in the shadow gets there exclusively by horizontal (three-dimensional) transport of photons in a spherical shell atmosphere. In this study the first accurate simulations are presented examplified by the solar eclipse at 29 March 2006. Using a backward Monte Carlo model we calculated the diffuse radiation in the umbra and simulated the changing colors of the sky. Radiance and irradiance are decreased by 3 to 4 orders of magnitude, depending on wavelength. We found that aerosol has a comparatively small impact on the radiation in the umbra. We also estimated the contribution of the solar corona to the radiation under the umbra and found that it is negligible compared to the diffuse solar radiation in most parts of the spectrum. Spectrally resolved measurements in the umbra are not yet available. They are challenging due to the low intensity and therefore need careful planning. The new model may be used to support measurements during future solar eclipses.

Emde, C.; Mayer, B.

2007-01-01

427

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

428

Semiconductor radiation detector  

SciTech Connect

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

429

Space radiation protection issues.  

PubMed

The complex charged particle environments in space pose considerable challenges with regard to potential health consequences that can impact mission design and crew selection. The lack of knowledge of the biological effects of different ions in isolation and in combination is a particular concern because the risk uncertainties are very high for both cancer and non-cancer late effects. Reducing the uncertainties is of high priority. Two principal components of space radiation each raise different concerns. Solar particle events (SPE) occur sporadically and are comprised primarily of low- to moderate-energy protons. Galactic cosmic radiation (GCR) is isotropic and relatively invariant in dose rate. GCR is also dominated by protons, but the energy range is wider than in SPE. In addition, the contribution of other light and heavy ions to the health risks from GCR must be addressed. This paper will introduce the principal issues under consideration for space radiation protection. PMID:23032885

Kronenberg, Amy; Cucinotta, Francis A

2012-11-01

430

Properties of undulator radiation  

SciTech Connect

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. 5 refs., 11 figs.

Veal, B.W.

1985-11-01

431

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

432

Audible radiation monitor  

DOEpatents

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

1993-01-01

433

Continuum radiation at Uranus  

NASA Astrophysics Data System (ADS)

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 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. It is argued 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.; Desch, M. D.

1990-02-01

434

Extragalactic Background Radiation  

NASA Astrophysics Data System (ADS)

Contents; Preface; List of participants; 1. Introduction P. J. E. Peebles; 2. Extragalactic gamma-ray background N. Gehrels and C. Cheung; 3. The X-ray background (observations) G. Zamorani; 4. Extragalactic ultraviolet background radiation R. C. Henry and J. Murthy; 5. Ultraviolet background (theory) P. Jakobsen; 6. The optical extragalactic background radiation J. A. Tyson; 7. Infrared background (observations) M. G. Hauser; 8. The infrared background (theory) C. J. Lonsdale; 9. Microwave background radiation (observations) J. C. Mather; 10. Detection of degree scale anisotropy P. M. Lubin; 11. Cosmic microwave background anisotropies and structure formation in the universe N. Vittorio; The radio background emission - the long and short of it M. S. Longair; 13. The radio background: radio-loud galaxies at high and low redshifts J. A. Peacock; 14. Conference summary M. J. Rees.

Calzetti, Daniela; Livio, Mario; Madau, Piero

1995-01-01

435

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.

436

String radiative backreaction  

SciTech Connect

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

Battye, R.A.; Shellard, E.P. [Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Silver Street, Cambridge, CB3 9EW (United Kingdom)]|[Isaac Newton Institute for Mathematical Sciences, Clarkson Road, Cambridge CB3 0EH (United Kingdom)

1995-12-01

437

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

438

Radiation techniques for acromegaly  

PubMed Central

Radiotherapy (RT) remains an effective treatment in patients with acromegaly refractory to medical and/or surgical interventions, with durable tumor control and biochemical remission; however, there are still concerns about delayed biochemical effect and potential late toxicity of radiation treatment, especially high rates of hypopituitarism. Stereotactic radiotherapy has been developed as a more accurate technique of irradiation with more precise tumour localization and consequently a reduction in the volume of normal tissue, particularly the brain, irradiated to high radiation doses. Radiation can be delivered in a single fraction by stereotactic radiosurgery (SRS) or as fractionated stereotactic radiotherapy (FSRT) in which smaller doses are delivered over 5-6 weeks in 25-30 treatments. A review of the recent literature suggests that pituitary irradiation is an effective treatment for acromegaly. Stereotactic techniques for GH-secreting pituitary tumors are discussed with the aim to define the efficacy and potential adverse effects of each of these techniques.

2011-01-01

439

New radiative shocks experiment  

NASA Astrophysics Data System (ADS)

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

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

2002-06-01

440

Personal radiation dosimeter  

SciTech Connect

A radiation dosimeter is described comprising: at least a first capacitive ionization chamber adapted to gradually discharge in the presence of incident radiation; a voltage source; a load resistor coupled to the voltage source; a first switch means coupled to the load resistor and the voltage source to form a first in-series circuit comprising the voltage source, the load resistor and the first switch means; a second switch means coupled to the load resistor and the voltage source to form a second in-series circuit comprising the voltage source, the load resistor, the second switch means and at least first capacitive ionization chamber; peak voltage sensing means coupled across the load resistor for providing a peak voltage signal; and calculating means responsive to peak voltage measurements taken across the load resistor as the first and second switch means are sequentially actuated for calculating the amount of radiation incident on the dosimeter from the peak voltage measurements.

Terhune, J.H.

1986-08-12

441

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

442

Effect of Surface Radiation on the Natural-Convection Stability in a Two-Dimensional Enclosure with Diffusely Emitting Boundary Walls  

Microsoft Academic Search

A transient interaction of natural convection with thermal radiation of gray surfaces of a square cavity filled with air is investigated numerically. The effect of radiation on the flow field, temperature distribution, and onset of oscillatory instability of flow is predicted. A complete study of stability of some value of Rayleigh number is performed for emissivity ? varying from 0

S. Jaballah; H. Sammouda; A. Belghith

2007-01-01

443

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

444

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

445

The radiative Reynolds number  

NASA Astrophysics Data System (ADS)

The radiative Reynolds number (RRN) is defined as a parameter characterizing the stability of low-temperature current-carrying plasma in high-current radiating discharges (such as are used for the pumping of high-power lasers). The RRN approach is used to examine the stability of plasmas and other objects in fields of intrinsic thermal emission; processes in MHD converters, gas lasers, and the cosmic plasma are examined. It is shown that in all cases where the RRN is sufficiently large the overheating instability (such as occurs in the solar photosphere) arises and the plasma becomes turbulent.

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

446

Diffraction radiation generators  

NASA Astrophysics Data System (ADS)

Research in the field of diffraction radiation generators (DRG) conducted at the Radio Physics and electronics Institute of the Ukranian Academy of Sciences over the past 25 years is reviewed. The effect of diffraction radiation is analyzed in detail, and various operating regimes of DRGs are discussed. The discussion then focuses on the principal requirements for the design of packaged DRGs and their principal parameters. Finally, applications of DRGs in various fields of science and technology are reviewed, including such applications as DRG spectroscopy, diagnostics of plasma, biological specimens, and vibration, and DRG radar systems.

Shestopalov, Viktor P.; Vertii, Aleksei A.; Ermak, Gennadii P.; Skrynnik, Boris K.; Khlopov, Grigorii I.; Tsvyk, Aleksei I.

447

Radiation Detectors and Art  

NASA Astrophysics Data System (ADS)

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

Denker, Andrea

448

Weak radiative hyperon decays  

NASA Astrophysics Data System (ADS)

The problem of weak radiative hyperon decays (WRHD) is reviewed. With the rcent measurement of the ?0 -> ?? asymmetry confirming Hara's theorem, implications from its violation in low-energy theoretical approaches are discussed. It is shown how an underlying symmetry link should be formulated for a successful description of both nonleptonic and radiative weak hyperon decays. The sign of the ?0 -> ?? asymmetry and the overall size of parity-violating WRHD amplitudes together lead to the resolution of the old S:P problem in nonleptonic decays.

?enczykowski, P.

2003-02-01

449

Control of radiation injury  

US Patent & Trademark Office Database

Methods of treating radiation injury of a subject in need thereof comprising administering to the subject a peptide consisting of an amino acid molecule selected from the group consisting of VVC, LAG, AQG, LQGV, QVVC, MTRV, LAGV, LQAV, PGCP, VGQL, RVLQ, EMFQ, AVAL, FVLS, NMWD, LCFL, FSYA, FWVD, AFTV, LGTL, QLLG, YAIT, APSL, ITTL, QALG, GVLC, NLIN, SPIE, LNTI, LHNL, CPVQ, EVVR, MTEV, EALE, EPPE, LGTL, VGGI, RLPG, LQGA, LCFL, TLAVE, VEGNL, LNEAL, CPRGVNP, MGGTWA, LTCDDP, VCNYRDV, QPLAPLVG, and DINGFLPAL. The invention provides for administration of the peptide prior to and following exposure of the subject to a source of radiation.

Benner; Robbert (Barendrecht, NL); Khan; Nisar Ahmed (Rotterdam, NL); Carlton; Richard Michael (Washington, NY)

2012-10-16

450

Modification of radiation response  

SciTech Connect

There has been a substantial and intense interest by laboratory and clinical investigators in the development of agents which modify the response of tissue to radiation differentially so as to increase the effect on tumor relative to normal tissue. These have included efforts to increase the response of tumor or to decrease response of normal tissue. The plan of this presentation is to: define radiation response modifiers; consider the impact of response modifiers on dose response curves; comment on problems inherent in assessment of results of clinical trials of response modifiers; and review briefly results of several trials of: sensitizers of hypoxic cells (hyperbaric oxygen, chemical sensitizer), pyrimidine analogs, and protectors.

Suit, H.D.

1984-01-01

451

RADIATION MEASURING DEVICES  

DOEpatents

A radiation-measuring device is described having an a-c output. The apparatus has a high-energy particle source responsive to radiation flux disposed within a housing having a pair of collector plates. A potential gradient between the source and collector plates causes ions to flow to the plates. By means of electrostatic or magnetic deflection elements connected to an alternating potential, the ions are caused to flow alternately to each of the collector plates causing an a-c signal thereon.

Bouricius, G.M.B.; Rusch, G.K.

1960-03-22

452

Radiation Imaging and Attenuation  

NASA Astrophysics Data System (ADS)

X-ray and neutron images are used to demonstrate materials' different radiation attenuation properties. This leads to discussion of applications in medicine, industry and research. The Penn State Radiation Science and Engineering Center (RSEC) uses neutron radioscopy to image the inside of a working hydrogen fuel cell. This is one of the many educational activities that are conducted when students visit the RSEC. To encourage pre-college students to apply these principles and learn more about nuclear technology, we are sponsoring a design competition. For more information visit www.rsec.psu.edu

Davison, Candace; Yocum, Douglas

2008-03-01

453

THz radiation sensors  

NASA Astrophysics Data System (ADS)

In the paper, issues associated with the development and exploitation of terahertz (THz) radiation detectors are discussed. The paper is written for those readers who desire an analysis of the latest developments in different type of THz radiation sensors (detectors), which play an increasing role in different areas of human activity (e.g., security, biological, drugs and explosions detection, imaging, astronomy applications, etc.). The basic physical phenomena and the recent progress in both direct and heterodyne detectors are discussed. More details concern Schottky barrier diodes, pair braking detectors, hot electron mixers, and field-effect transistor detectors. Also the operational conditions of THz detectors and their upper performance limits are discussed.

Sizov, F.

2010-03-01

454

Radial diffusion of relativistic electrons into the radiation belt slot region during the 2003 Halloween geomagnetic storms  

Microsoft Academic Search

A study was undertaken to estimate the radial diffusion timescale, tauLL, for relativistic electrons (2-6 MeV) to diffuse into the slot region due to drift-resonance with Pc5 ULF waves (2-10 mHz) on 29 October 2003. Large amplitude ULF waves were observed by ground-based magnetometer arrays to penetrate deep into the slot region (L $\\\\simeq$ 2-3) starting at 0600 UT and

T. M. Loto'aniu; I. R. Mann; L. G. Ozeke; A. A. Chan; Z. C. Dent; D. K. Milling

2006-01-01

455

Radial diffusion of relativistic electrons into the radiation belt slot region during the 2003 Halloween geomagnetic storms  

Microsoft Academic Search

A study was undertaken to estimate the radial diffusion timescale, ?LL, for relativistic electrons (2–6 MeV) to diffuse into the slot region due to drift-resonance with Pc5 ULF waves (2–10 mHz) on 29 October 2003. Large amplitude ULF waves were observed by ground-based magnetometer arrays to penetrate deep into the slot region (L$\\\\simeq$ 2–3) starting at 0600 UT and maximising

T. M. Loto'aniu; I. R. Mann; L. G. Ozeke; A. A. Chan; Z. C. Dent; D. K. Milling

2006-01-01

456

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

Microsoft Academic Search

We use the first data release from the SINGG Halpha survey of H I-selected galaxies to study the quantitative behavior of the diffuse, warm ionized medium (WIM) across the range of properties represented by these 109 galaxies. The mean fraction fWIM of diffuse ionized gas in this sample is 0.59+\\/-0.19, slightly higher than found in previous samples. Since lower surface

M. S. Oey; G. R. Meurer; S. Yelda; E. J. Furst; S. M. Caballero-Nieves; D. J. Hanish; E. M. Levesque; D. A. Thilker; G. L. Walth; J. Bland-Hawthorn; M. A. Dopita; H. C. Ferguson; T. M. Heckman; M. T. Doyle; M. J. Drinkwater; K. C. Freeman; R. C. Kennicutt Jr.; V. A. Kilborn; P. M. Knezek; M. Meyer; M. E. Putman; E. V. Ryan-Weber; R. C. Smith; L. Staveley-Smith; R. L. Webster; J. Werk; M. A. Zwaan

2007-01-01

457

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

458

Bounce-averaged diffusion coefficients due to resonant interaction of the outer radiation belt electrons with oblique chorus waves computed in a realistic magnetic field model  

NASA Astrophysics Data System (ADS)

We present the results of calculations of the bounce-averaged pitch angle, mixed, and momentum diffusion coefficients in a dipole and two realistic field models (the T01s model for quiet and storm conditions). We consider resonant interactions of the outer radiation belt electrons with oblique chorus waves. We demonstrate that on the dayside, the use of a realistic magnetic field versus a dipole field only makes a significant difference for small equatorial pitch angles at energies larger than E = 1 MeV. On the nightside, the differences between the scattering rates calculated in the Tsyganenko and dipole models can reach several orders of magnitude at various equatorial pitch angles for electrons with E ? 0.5 MeV. The most significant changes in the scattering rates computed in the realistic and dipole magnetic fields occur during the geomagnetically active conditions. On the nightside, for E ? 0.5 MeV, the diffusion coefficients calculated in the Tsyganenko field show significant scattering near the edge of the loss cone that can produce loss of electrons to the atmosphere, while in the dipole model there is no scattering at small equatorial pitch angles. Our computations in the realistic field show that resonant interactions between electrons with E ? 1 MeV and chorus waves can be an effective net loss mechanism on both the dayside and the nightside. To explain the differences in the scattering rates associated with a change in the magnetic field model, we present the contribution of various resonant harmonics to the diffusion and examine the changes in the resonance condition.

Orlova, Ksenia G.; Shprits, Yuri Y.; Ni, Binbin

2012-07-01

459

Verification of the Radiation Package in ALEGRA  

SciTech Connect

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

Budge, K.G.

1999-04-01

460

Radiation Hard Fiber Optics.  

National Technical Information Service (NTIS)

A study of radiation-inducted absorption in low-loss optical waveguides is reported. Step-index optical fibers were prepared from preforms fabricated by the CVD method. The germanium silicate core glass in the fibers was doped with varying amounts of anti...

R. E. Jaeger M. Aslami

1981-01-01

461

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