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1

Diffuse Background Radiation  

E-print Network

A new determination of the upper limit to the cosmic diffuse background radiation, at ~110 nm, of 300 photons s-1 cm-2 sr-1 nm-1, is placed in the context of diffuse background measurements across the entire electromagnetic spectrum, including new optical, infrared, visible, and gamma-ray background measurements. The possibility that observed excess diffuse visible radiation is due to redshifted cosmological Lyman alpha recomination radiation is explored. Also, a new standard of units for the display of spectra is advocated.

Richard C. Henry

1999-03-18

2

Adaptive multigroup radiation diffusion  

E-print Network

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

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

2005-01-01

3

Diffuse UV erythemal radiation experimental values  

NASA Astrophysics Data System (ADS)

Measurements of diffuse UV erythemal radiation (UVER) using a shadowband have been corrected using the models proposed by Drummond (1956), LeBaron et al. (1990), and Batlles et al. (1995). Two different methods were used to validate these models: intercomparison with an Optronic OL754 spectroradiometer and comparison with the values simulated by two radiative transfer codes, SMARTS and SBDART. For this comparison only clear days have been used. The corrected experimental values were analyzed in order to study the average values of the diffuse UVER fraction in relation to the clearness index kt. These varied between 62%, for kt close to 0.8, and 93% for kt of 0.2-0.3. Finally, a study of the monthly average and extreme values of the UV Index for diffuse radiation is presented, showing a maximum value of 6 in June.

Utrillas, M. P.; MaríN, M. J.; Esteve, A. R.; Tena, F.; CañAda, J.; EstelléS, V.; MartíNez-Lozano, J. A.

2007-12-01

4

Assessment of diffuse radiation models in Azores  

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

5

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

6

Radiation  

Cancer.gov

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

7

Radiators  

SciTech Connect

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

Webster, D. M.

1985-07-30

8

Simulating seasonal patterns of increased greenhouse crop production by conversion of direct radiation into diffuse radiation  

Microsoft Academic Search

The conversion of direct solar photosynthetically active radiation (PARDir) into diffuse radiation (PARDif) and its effects on greenhouse crop production were analyzed with simulation models. PARDir can be converted into PARDif by increasing the haze of greenhouse covers with a minimal loss of radiation transmission. At specific sun incidence angles, PARDif penetrates more deeply into the canopy than PARDir, thereby

R. E. E. Jongschaap; T. A. Dueck; S. Hemming; L. F. M. Marcelis; A. Marissen

2006-01-01

9

Effect of the diffuse solar radiation on photovoltaic inverter output  

Microsoft Academic Search

Solar global irradiance received at a horizontal level on the earth varies significantly over short intervals due to diffuse radiation changes. Experimental data on global irradiance profiles received by fast data recording systems show that the global irradiance may be enhanced for a few minute periods by as much as 40%. The diffuse radiation is intensified by dry air mass

C. A. Balafas; M. D. Athanassopoulou; T. Argyropoulos; P. Skafidas; C. T. Dervos

2010-01-01

10

Correlation of total, diffuse, and direct solar radiation  

NASA Technical Reports Server (NTRS)

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

Buyco, E. H.; Namkoong, D.

1977-01-01

11

Discrete diffusion Monte Carlo for frequency-dependent radiative transfer  

SciTech Connect

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

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

2010-11-17

12

Radiation Diffusion:. AN Overview of Physical and Numerical Concepts  

NASA Astrophysics Data System (ADS)

An overview of the physical and mathematical foundations of radiation transport is given. Emphasis is placed on how the diffusion approximation and its transport corrections arise. An overview of the numerical handling of radiation diffusion coupled to matter is also given. Discussions center on partial temperature and grey methods with comments concerning fully implicit methods. In addition finite difference, finite element and Pert representations of the div-grad operator is also discussed

Graziani, Frank

2005-12-01

13

Diffuse solar radiation and associated meteorological parameters in India  

NASA Astrophysics Data System (ADS)

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

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

1996-10-01

14

Radiative extinction of gaseous spherical diffusion flames in microgravity  

Microsoft Academic Search

Radiative extinction of spherical diffusion flames was investigated experimentally and numerically. The experiments involved microgravity spherical diffusion flames burning ethylene and propane at 0.98 bar. Both normal (fuel flowing into oxidizer) and inverse (oxidizer flowing into fuel) flames were studied, with nitrogen supplied to either the fuel or the oxygen. Flame conditions were chosen to ensure that the flames extinguished

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

2007-01-01

15

Response of radiation belt simulations to different radial diffusion coefficients  

NASA Astrophysics Data System (ADS)

Resonant interactions between Ultra Low Frequency (ULF) waves and relativistic electrons may violate the third adiabatic invariant of motion, which produces radial diffusion in the electron radiation belts. This process plays an important role in the formation and structure of the outer electron radiation belt and is important for electron acceleration and losses in that region. Two parameterizations of the resonant wave-particle interaction of electrons with ULF waves in the magnetosphere by Brautigam and Albert [2000] and Ozeke et al. [2012] are evaluated using the Versatile Electron Radiation Belt (VERB) diffusion code to estimate their relative effect on the radiation belt simulation. The period of investigation includes quiet time and storm time geomagnetic activity and is compared to data based on satellite observations. Our calculations take into account wave-particle interactions represented by radial diffusion transport, local acceleration, losses due to pitch-angle diffusion, and mixed diffusion. We show that the results of the 3D diffusion simulations depend on the assumed parametrization of waves. The differences between the simulations and potential missing physical mechanisms are discussed. References Brautigam, D. H., and J. M. Albert (2000), Radial diffusion analysis of outer radiation belt electrons during the October 9, 1990, magnetic storm, J. Geophys. Res., 105(A1), 291-309, doi:10.1029/1999JA900344 Ozeke, L. G., I. R. Mann, K. R. Murphy, I. J. Rae, D. K. Milling, S. R. Elkington, A. A. Chan, and H. J. Singer (2012), ULF wave derived radiation belt radial diffusion coefficients, J. Geophys. Res., 117, A04222, doi:10.1029/2011JA017463.

Drozdov, A.; Shprits, Y.; Subbotin, D.; Kellerman, A. C.

2013-12-01

16

Radiative Extinction of Gaseous Spherical Diffusion Flames in Microgravity  

NASA Technical Reports Server (NTRS)

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

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

2007-01-01

17

PRECONDITIONING A MIXED DISCONTINUOUS FINITE ELEMENT METHOD FOR RADIATION DIFFUSION  

SciTech Connect

We propose a multilevel preconditioning strategy for the iterative solution of large sparse linear systems arising from a finite element discretization of the radiation diffusion equations. In particular, these equations are solved using a mixed finite element scheme in order to make the discretization discontinuous, which is imposed by the application in which the diffusion equation will be embedded. The essence of the preconditioner is to use a continuous discretization of the original, elliptic diffusion equation for preconditioning the discontinuous equations. We have found that this preconditioner is very effective and makes the iterative solution of the discontinuous diffusion equations practical for large problems. This approach should be applicable to discontinuous discretizations of other elliptic equations. We show how our preconditioner is developed and applied to radiation diffusion problems on unstructured, tetrahedral meshes and show numerical results that illustrate its effectiveness.

JAMES S. WARSA; MICHELE BENZI; TODD A. WAREING; JIM E. MOREL

2002-06-18

18

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

NASA Technical Reports Server (NTRS)

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

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

1976-01-01

19

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

20

Comparison of the Radiative Two-Flux and Diffusion Approximations  

NASA Technical Reports Server (NTRS)

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

Spuckler, Charles M.

2006-01-01

21

Pulsar and diffuse contributions to the observed galactic gamma radiation  

NASA Technical Reports Server (NTRS)

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

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

1980-01-01

22

The origin of the diffuse background gamma-radiation  

NASA Technical Reports Server (NTRS)

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

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

1974-01-01

23

A model for calculating direct and diffuse solar radiation  

NASA Astrophysics Data System (ADS)

A model for computing both direct and diffuse solar radiation for a cloudy sky is developed, using King and Buckius (1979) calculations of the direct component for a clear sky. Data on daily global insolation incidents on a horizontal surface at Ibadan/Nigeria, calculated for the year 1977, pertained to dew point temperature, visibility, and daily sunshine duration for the city, while a second set of data represented total daily insolation. Out of two cloudiness coefficients, 1.0 and 0.75, the latter gave results that compared favorably with the data. Charts indicating the monthly average values of daily direct and diffuse radiation and daily global insolation, using the two coefficients, are given. It is suggested that the model be applied to other geographical regions.

Ideriah, F. J. K.

24

ULF wave derived radiation belt radial diffusion coefficients  

NASA Astrophysics Data System (ADS)

Waves in the ultra-low-frequency (ULF) band have frequencies which can be drift resonant with electrons in the outer radiation belt, suggesting the potential for strong interactions and enhanced radial diffusion. Previous radial diffusion coefficient models such as those presented by Brautigam and Albert (2000) have typically used semiempirical representations for both the ULF wave's electric and magnetic field power spectral densities (PSD) in space in the magnetic equatorial plane. In contrast, here we use ground- and space-based observations of ULF wave power to characterize the electric and magnetic diffusion coefficients. Expressions for the electric field power spectral densities are derived from ground-based magnetometer measurements of the magnetic field PSD, and in situ AMPTE and GOES spacecraft measurements are used to derive expressions for the compressional magnetic field PSD as functions of Kp, solar wind speed, and L-shell. Magnetic PSD results measured on the ground are mapped along the field line to give the electric field PSD in the equatorial plane assuming a guided Alfvén wave solution and a thin sheet ionosphere. The ULF wave PSDs are then used to derive a set of new ULF-wave driven diffusion coefficients. These new diffusion coefficients are compared to estimates of the electric and magnetic field diffusion coefficients made by Brautigam and Albert (2000) and Brautigam et al. (2005). Significantly, our results, derived explicitly from ULF wave observations, indicate that electric field diffusion is much more important than magnetic field diffusion in the transport and energization of the radiation belt electrons.

Ozeke, Louis G.; Mann, Ian R.; Murphy, Kyle R.; Rae, I. Jonathan; Milling, David K.; Elkington, Scot R.; Chan, Anthony A.; Singer, Howard J.

2012-04-01

25

Radiation-enhanced self- and boron diffusion in germanium  

NASA Astrophysics Data System (ADS)

We report experiments on proton radiation-enhanced self- and boron (B) diffusion in germanium (Ge) for temperatures between 515 ?C and 720 ?C. Modeling of the experimental diffusion profiles measured by means of secondary ion mass spectrometry is achieved on the basis of the Frenkel pair reaction and the interstitialcy and dissociative diffusion mechanisms. The numerical simulations ascertain concentrations of Ge interstitials and B-interstitial pairs that deviate by several orders of magnitude from their thermal equilibrium values. The dominance of self-interstitial related defects under irradiation leads to an enhanced self- and B diffusion in Ge. Analysis of the experimental profiles yields data for the diffusion of self-interstitials (I) and the thermal equilibrium concentration of BI pairs in Ge. The temperature dependence of these quantities provides the migration enthalpy of I and formation enthalpy of BI that are compared with recent results of atomistic calculations. The behavior of self- and B diffusion in Ge under concurrent annealing and irradiation is strongly affected by the property of the Ge surface to hinder the annihilation of self-interstitials. The limited annihilation efficiency of the Ge surface can be caused by donor-type surface states favored under vacuum annealing, but the physical origin remains unsolved.

Schneider, S.; Bracht, H.; Klug, J. N.; Hansen, J. Lundsgaard; Larsen, A. Nylandsted; Bougeard, D.; Haller, E. E.

2013-03-01

26

The Gamma-ray galactic diffuse radiation and Cerenkov telescopes  

SciTech Connect

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

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

1995-12-01

27

Photoacoustic imaging of prostate cancer using cylinder diffuse radiation  

NASA Astrophysics Data System (ADS)

Prostate cancer is one of diseases with high mortality in man. Many clinical imaging modalities are utilized for the detection, grading and staging of prostate cancer, such as ultrasound, CT, MRI, etc. But they lacked adequate sensitivity and specificity for finding cancer in transition or central zone of prostate. To overcome these problems, we propose a photoacoustic imaging modality based on cylinder diffuse radiation through urethra for prostate cancer detection. We measure the related parameters about this system like lateral resolution (~2mm) and axial resolution(~333?m). Finally, simulated sample was imaged by our system. The results demonstrate the feasibility for detecting prostate cancer by our system.

Xie, Wenming; Li, Li; Li, Zhifang; Li, Hui

2012-12-01

28

Soot and Radiation Measurements in Microgravity Jet Diffusion Flames  

NASA Technical Reports Server (NTRS)

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

Ku, Jerry C.

1996-01-01

29

Newton-Krylov methods applied to nonequilibrium radiation diffusion  

SciTech Connect

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

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

1998-03-10

30

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

31

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

NASA Astrophysics Data System (ADS)

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

Obara, Shin'ya

32

Filling of glass microshells with heavy gases by radiation-simulated diffusion  

Microsoft Academic Search

The research results of an opportunity of radiation-stimulated diffusion use for laser fusion microtargets filling with heavy gases are given, which they can not be filled with by means of usual diffusion. The theoretical estimates of quantity and character of radiation damages, their distribution in the volume of an irradiated material are made. The calculations of glass microshells argon filling

V. M. Izgorodin; S. N. Abramovich; V. G. Gogolev; N. V. Zhidkov; Yu V. Ignat'ev; A. E. Lakhtikov; A. P. Morovov; G. P. Nikolayev; V. N. Protopopov; V. T. Punin; V. A. Starodubtsev; B. V. Ferapontov; Yu. N. Khirnii; Yu. A. Khokhlov; V. V. Chulkov

2003-01-01

33

Convective and diffusive ULF wave driven radiation belt electron transport  

NASA Astrophysics Data System (ADS)

The process of magnetospheric radiation belt electron transport driven by ULF waves is studied using a 2-D ideal MHD model for ULF waves in the equatorial plane including day/night asymmetry and a magnetopause boundary, and a test kinetic model for equatorially mirroring electrons. We find that ULF wave disturbances originating along the magnetopause flanks in the afternoon sector can act to periodically inject phase space density from these regions into the magnetosphere. Closely spaced drift-resonant surfaces for electrons with a given magnetic moment in the presence of the ULF waves create a layer of stochastic dynamics for L-shells above 6.5-7 in the cases examined, extending to the magnetopause. The phase decorrelation time scale for the stochastic region is estimated by the relaxation time for the diffusion coefficient to reach a steady value. This is found to be of the order of 10-15 wave periods, which is commensurate with the typical duration of observed ULF wave packets in the magnetosphere. For L-shells earthward of the stochastic layer, transport is limited to isolated drift-resonant islands in the case of narrowband ULF waves. We examine the effect of increasing the bandwidth of the ULF wave driver by summing together wave components produced by a set of independent runs of the ULF wave model. The wave source spectrum is given a flat-top amplitude of variable width (adjusted for constant power) and random phase. We find that increasing bandwidth can significantly enhance convective transport earthward of the stochastic layer and extend the stochastic layer to lower L-shells.

Degeling, A. W.; Rankin, R.; Elkington, S. R.

2011-12-01

34

Modeling the radiation belt electrons with radial diffusion driven by the solar wind  

E-print Network

Modeling the radiation belt electrons with radial diffusion driven by the solar wind A. B. Barker1 October 2005. [1] On the basis of the correlation between the solar wind and radiation belt electron fluxes, we develop a model to simulate the MeV electron phase space density variations from L = 3 to L

Li, Xinlin

35

Soot formation and radiation in turbulent jet diffusion flames under normal and reduced gravity conditions  

NASA Technical Reports Server (NTRS)

Most practical combustion processes, as well as fires and explosions, exhibit some characteristics of turbulent diffusion flames. For hydrocarbon fuels, the presence of soot particles significantly increases the level of radiative heat transfer from flames. In some cases, flame radiation can reach up to 75 percent of the heat release by combustion. Laminar diffusion flame results show that radiation becomes stronger under reduced gravity conditions. Therefore, detailed soot formation and radiation must be included in the flame structure analysis. A study of sooting turbulent diffusion flames under reduced-gravity conditions will not only provide necessary information for such practical issues as spacecraft fire safety, but also develop better understanding of fundamentals for diffusion combustion. In this paper, a summary of the work to date and of future plans is reported.

Ku, Jerry C.; Tong, LI; Sun, Jun; Greenberg, Paul S.; Griffin, Devon W.

1993-01-01

36

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

E-print Network

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

Munger, Bryce Kirtley

2012-06-07

37

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

E-print Network

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

Munger, B.; Haberl, J. S.

1994-01-01

38

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

NASA Technical Reports Server (NTRS)

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

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

1995-01-01

39

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

40

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

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

41

A comparison of the photosynthetic radiation response of Scots pine shoots in direct and diffuse radiation  

E-print Network

an open flow IRGA- system (URAS 3G). The temperature in the assimilation chamber was 20°C, ambient C02 concentration was 340 ppm and the air water vapor pressure deficit was 9 ± 1 mbar. The distribution of radiation

Paris-Sud XI, Université de

42

Heat transfer including particle and gas radiation in subsonic MHD diffuser-II  

SciTech Connect

Heat transfer in subsonic MHD diffusers, by convection and by gas and slag particle radiation, is analyzed by simultaneously solving the radiation transport equation and the quasi-three-dimensional gasdynamic equations. The efficiency factors for extinction and scattering by particles are calculated from the Mie theory. For a reference diffuser geometry, the heat transfer by convection is found to be 25 MW, and the radiative heat transfer varies from 44 MW to 79 MW, depending on the rate of ash carryover into the channel. Results reveal that the heat transfer is sensitive to the ash carryover into the channel, slag particles spectrum, electrical conductivity of ash, gas composition, and wall emissivity. It is observed that, because of multiple scattering, the particles shield the short wavelength radiation emitted by potassium atoms. The impacts of heat transfer enhancement by gas radiation in the channel and by gas-plus-particles radiation in the diffuser on MHD system design are assessed. It is suggested that, from the system design point of view, the diffuser be regarded as a part of the radiant boiler. No significant effect of radiation enhancement on the ability to decompose NO/sub x/ is anticipated.

Ahluwalia, R.K.; Im, K.H.

1980-01-01

43

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

E-print Network

and associated meteorological parameters in India A. B. Bhattacharya, S. K. Kar, R. Bhattacharya Department: 15 May 1996/Accepted: 27 May 1996 Abstract. Solar diffuse radiation data including global radiation are presented together with some meteorological parameters. The monthly values of diffuse radiation

Boyer, Edmond

44

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

SciTech Connect

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

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

1998-09-01

45

An efficient diffusion approximation for 3D radiative transfer parameterization: application to cloudy atmospheres  

Microsoft Academic Search

The three-dimensional (3D) diffusion radiative transfer equation, which utilizes a four-term spherical harmonics expansion for the scattering phase function and intensity, has been efficiently solved by using the full multigrid numerical method. This approach can simulate the transfer of solar and thermal infrared radiation in inhomogeneous cloudy conditions with different boundary conditions and sharp boundary discontinuity. The correlated k-distribution method

Y. Chen; K. N. Liou; Y. Gu

2005-01-01

46

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

47

Measure of Diffusion Model Error for Thermal Radiation Transport  

E-print Network

of the diffusion model error called the diffusion model error source (DME source). When this DME source is added to the diffusion equation, the transport solution for the angular-integrated intensity is obtained. In contrast to the variable-Eddington tensor, our...

Kumar, Akansha

2013-04-19

48

Short-term changes in Jupiter's synchrotron radiation at 325 MHz: Enhanced radial diffusion in Jupiter's radiation belt driven by solar UV\\/EUV heating  

Microsoft Academic Search

Evidence of short-term changes in Jupiter's synchrotron radiaion at 325 MHzRadial diffusion rate of 3 × 10?8 L3 \\/s is suitable in Jupiter's radiation beltThe synchrotron emission does not contribute electron loss in the radiation belt

F. Tsuchiya; H. Misawa; K. Imai; A. Morioka

2011-01-01

49

Process of defect formation and diffusion in metals induced by laser radiation  

NASA Astrophysics Data System (ADS)

There have been conducted researches for the presence of defects in specimens of repined carbonyl iron after the treatment by continuous radiation of C02-laser under subcritical conditions. High degree of presence of the defects is characterized by appearance of cellular dislocation structure and by considerable oversaturation of vacancies. There have been also investigated the conditions of realization of an accelerated diffusion of boron in iron and steels in treating by continuous radiation of CD2-- laser. It was revealed that the boron redistribution from the previously created layer of borides on the metal surface is accomplished in steels to the depthes of up to 3 mm. The accelerated oxygen diffusion stimulated by the laser radiation has been investigated on the basis of the obtained results of the process of internal oxidation of alloy Cu-Sn (0. 55 at 7. ). There has been proposed the model of process of accelerated transport. 2. FORMATION OF DEFECTS IN CARBONYL IRON UNDER CONTINUOUS LASER RADIATION The investigation of the defect formation under the continuous laser radiation 10. 6 sam) was conducted with the specimens (4x0. 8x80) mm of carbonyl iron 0. 008 C 0. 047 Mn Al + Si + S) refined in hydrogen atmosphere. The laser treatment was accomplished without flashing the metal surface. Treatment characteristics: radiation power P (0. 25-1. 1 kV. Specimen displacement speed under the laser beam V (10-2. 5) mm/s

Zvonkov, Alexander D.; Boranbaeva, H. M.

1990-10-01

50

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

51

Treatment of Low-grade Diffuse Astrocytomas by Surgery and Human Fibroblast Interferon without Radiation Therapy  

Microsoft Academic Search

Low-grade diffuse astrocytomas are slowly growing tumors with a relatively long overall survival. However, a substantial proportion undergoes dedifferentiation to a more malignant phenotype. Considerable controversy exists as to the best therapeutic management for patients with such tumors. Over the past decade, we have applied human fibroblast interferon (HFIF) therapy without radiation therapy to low-grade astrocytomas. We investigated 28 patients

Takao Watanabe; Yoichi Katayama; Atsuo Yoshino; Chiaki Komine; Takakazu Yokoyama; Takao Fukushima

2003-01-01

52

Consistency tests applied to the measurement of total, direct, and diffuse shortwave radiation at the surface  

Microsoft Academic Search

Motivated by recent studies suggesting that the clear-sky atmosphere absorbs more shortwave (solar) radiation than the theoretical models, we have performed two consistency tests on the data used in several of these studies. These data consist of broadband measurements of shortwave irradiance to the surface (total, direct, and diffuse) taken in Oklahoma. In the absence of aerosols, Rayleigh scattering is

Robert D. Cess; Taotao Qian; Moguo Sun

2000-01-01

53

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

Microsoft Academic Search

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

Alan Robock

2005-01-01

54

A study of radiation and flow properties of buoyant turbulent diffusion flames  

Microsoft Academic Search

Buoyant pool fires are representative of accidental and arson related fires resulting in extensive property damage and injury to people. Continued research in pool fires is needed to support technology based efforts to reduce fire losses. Motivated by this, a study of radiation and flow characteristics of two laboratory scale buoyant diffusion flames, mimicking pool fire behavior, was undertaken. ^

Kaushik Biswas

2007-01-01

55

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

56

Diffusion of sulfur into natural diamond: Characterization and applications in radiation detection  

NASA Astrophysics Data System (ADS)

A "second generation" doping reactor has been constructed, tested, and used to diffuse sulfur into polished, natural diamond plates. Different sulfur sources have been used for the incorporation of sulfur into the diamond lattice. Diffusion coefficients in the range of 10-15 cm2/s to 10-14 cm2 /s have been calculated for sulfur into natural diamond. The small decrease in optical transmission (5%) of the diamond samples after doping and the ohmic nature of the diffused layer indicate that the sulfur-doping of diamond may be a useful technique for the formation of electrical contacts on diamond-based radiation detectors.

West, Matthew Keith

57

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

SciTech Connect

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

Shestakov, Aleksei I., E-mail: shestakov1@llnl.gov

2013-06-15

58

The Mystery of the Cosmic Diffuse Ultraviolet Background Radiation  

E-print Network

and the observed FUV emission. Our modeling of the FUV scattering by small grains also shows that there must range. In the microwave the results of observation have been sufficiently important that they have led of the study of the UV background is brought out by Murthy (2009). Today, a powerful new diffuse UV background

59

Diffuse gamma radiation. [intensity, energy spectrum and spatial distribution from SAS 2 observations  

NASA Technical Reports Server (NTRS)

Results are reported for an investigation of the intensity, energy spectrum, and spatial distribution of the diffuse gamma radiation detected by SAS 2 away from the galactic plane in the energy range above 35 MeV. The gamma-ray data are compared with relevant data obtained at other wavelengths, including 21-cm emission, radio continuum radiation, and the limited UV and radio information on local molecular hydrogen. It is found that there are two quite distinct components to the diffuse radiation, one of which shows a good correlation with the galactic matter distribution and continuum radiation, while the other has a much steeper energy spectrum and appears to be isotropic at least on a coarse scale. The galactic component is interpreted in terms of its implications for both local and more distant regions of the Galaxy. The apparently isotropic radiation is discussed partly with regard to the constraints placed on possible models by the steep energy spectrum, the observed intensity, and an upper limit on the anisotropy.

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

1978-01-01

60

Sources of Cosmic Rays and Galactic Diffuse Gamma Radiation  

E-print Network

The diffuse galactic gamma-ray spectrum measured by the EGRET experiment \\citep{Hunter:1997} are interpreted within a scenario in which cosmic rays (CRs) are injected by three different kind of sources, (i) supernovae (SN) which explode into the interstellar medium (ISM), (ii) Red Supergiants (RSG), and (iii) Wolf-Rayet stars (WR), where the two latter explode into their pre-SN winds (Biermann et al. 2001; Sina et al. 2001).

Sabrina Casanova; Peter L. Biermann; Ralph Engel; Athina Meli; Ralf Ulrich

2004-03-29

61

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

NASA Astrophysics Data System (ADS)

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.

Gorpas, Dimitris; Andersson-Engels, Stefan

2012-12-01

62

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

NASA Astrophysics Data System (ADS)

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.

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

2013-06-01

63

Radiation enteritis  

MedlinePLUS

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

64

Very high energy gamma-ray absorption via localized diffuse radiation fields  

NASA Astrophysics Data System (ADS)

When Very High Energy (VHE) gamma-rays (E>100 GeV) transverse low energy photon fields, the production of electron-positron pairs leads to the attenuation of the intrinsic gamma-ray flux. This phenomena is well know for VHE radiation from extragalactic sources, like e.g. blazars, interacting with the cosmic infrared background. In this contribution the absorption of VHE gamma-rays due to the interaction with localized low energy radiation fields, e.g. the Milky Way diffuse radiation field, cluster radiation fields and radiation fields in voids and filaments is discussed. While the photon field densities of these inhomogeneous radiation fields can be several orders of magnitude higher compared to the homogeneous background, the distances are in general shorter leading to an overall smaller effect. On the other hand, the detection of such an attenuation could be used to study the IR emission on different scales, measure the distance of galactic sources, or investigate particle physics phenomena beyond the standard model. It is investigated how forthcoming imaging air Cherenkov telescopes, like CTA, and wide angle Cherenkov arrays, like HiSCORE, with their improved sensitivities up to several hundred TeV will measure this absorption feature.

Maurer, Andreas; Becerra-Gonzalez, Josefa; Raue, Martin; Horns, Dieter

2012-12-01

65

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

E-print Network

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

Chang-Hwan Lee; Ismail Zahed

2014-03-07

66

An Experimental and Theoretical Study of Radiative Extinction of Diffusion Flames  

NASA Technical Reports Server (NTRS)

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

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

1993-01-01

67

Radiative cooler. [spacecraft radiators  

NASA Technical Reports Server (NTRS)

A method and radiative cooling device for use in passively cooling spaces is described. It is applicable to any level of thermal radiation in vacuum and to high-intensity thermal radiation in non-vacuum environments. The device includes an enclosure nested in a multiplicity of thin, low-emittance, highly-reflective shields. The shields are suspended in a casing in mutual angular relation and having V-shaped spaces defined therebetween for redirecting, by reflection, toward the large openings of the V-shaped spaces, thermal radiation entering the sides of the shields, and emitted to the spaces, whereby successively reduced quantities of thermal radiation are reflected by the surfaces along substantially parallel paths extended through the V-shaped spaces to a common heat sink such as the cold thermal background of space.

Petrick, S. W.; Garcia, R. D. (inventors)

1984-01-01

68

Extinction of counterflow diffusion flames with radiative heat loss and nonunity Lewis numbers  

SciTech Connect

The structure and extinction characteristics of counterflow diffusion flames with flame radiation and nonunity Lewis numbers of the fuel and oxidant are examined using multiscale asymptotic theory, and a model expressed in terms of the jump relations and reactant leakages with the proper consideration of the excess enthalpy overlooked in previous analyses is developed. The existence of the dual extinction limits in the presence of radiative heat loss, namely the kinetic limit at small Damkoehler number (high stretch rate) and the radiative limit at large Damkoehler number (low stretch rate), are identified. It is found that the former is minimally affected by radiative loss, while a substantial amount of heat loss is associated with the radiative limit. Reactant leakage, however, is the root cause for both limits. The influence of radiative loss on the extinction Damkoehler numbers is found to be through its effects on the flame temperature, the excess enthalpy, and the reduced extinction Damkoehler number. At both extinction limits, the contribution from the flame temperature is always important and dominant. The contributions from the other two, however, could be important in some special cases. At small Le{sub F}, the contribution from the reduced extinction Damkoehler number is large and even dominant under small radiative loss. The contribution from the excess enthalpy is important for small Le{sub O} and it may be comparable to the contribution from the flame temperature when radiative loss is small. Thus, overlooking the excess enthalpy in previous analyses may have resulted in rather large error in the predicted extinction Damkoehler numbers, especially the kinetic one. (author)

Wang, H.Y.; Law, C.K. [Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ 08544-5263 (United States); Chen, W.H. [Department of Marine Engineering, National Taiwan Ocean University, Keelung (Taiwan)

2007-02-15

69

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

PubMed

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

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

2014-01-01

70

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

71

Diffusion Tensor Imaging for In Vivo Detection of Degenerated Optic Radiation  

PubMed Central

Glaucomatous optic nerve atrophy may continue to the linked optic radiation by transneuronal degeneration, as described in animal models of glaucoma. In vivo visualization of the visual pathway represents a new challenge in the field of ophthalmology. We present a new approach for illustration of the optic radiation by diffusion tensor imaging (DTI) based on magnetic resonance imaging (MRI). The DTI was established by use of a 3T high-field scanner. The case of a patient with primary open-angle glaucoma is opposed to this one of a healthy subject to demonstrate the visible rarefication of the optic radiation. The goal was to introduce the technique of the DTI also in ophthalmology and to demonstrate that it may be useful to judge glaucoma-related differences. PMID:24533184

Michelson, Georg; Engelhorn, Tobias; Waerntges, Simone; Doerfler, Arnd

2011-01-01

72

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

NASA Technical Reports Server (NTRS)

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

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

1983-01-01

73

Temperature and Radiative Heat Flux Measurements in Microgravity Jet Diffusion Flames  

NASA Technical Reports Server (NTRS)

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

Ku, Jerry C.; Greenberg, Paul S.

1997-01-01

74

An Experimental and Theoretical Study of Radiative Extinction of Diffusion Flames  

NASA Technical Reports Server (NTRS)

The objective of this work is to investigate the radiation-induced rich extinction limits for diffusion flames. Radiative extinction is caused by the formation of particulates (e.g., soot) that drain chemical energy from the flame. We examine (mu)g conditions because there is a strong reason to believe that radiation-induced rich-limit extinction is not possible under normal-gravity conditions. In normal- g, the hot particulates formed in the fuel-rich flames are swept upward by buoyancy, out of the flame to the region above it, where their influence on the flame is negligible. However, in (mu)g the particulates remain in the flame vicinity, creating a strong energy sink that can, under suitable conditions, cause flame extinction.

Wichman, Indrek S.

1993-01-01

75

Effect of Radiative Heat Transfer on Three-Dimensional Double Diffusive Natural Convection  

Microsoft Academic Search

This work presents a numerical study of the effect of the radiative heat transfer on the three-dimensional double diffusive convection in a differentially heated cubic cavity for different optical parameters of the medium. This numerical study is conducted for fixed Prandtl, Rayleigh, and Lewis numbers, Pr = 13.6, Ra = 10, Le = 2, and buoyancy ratio N in the range [–2, 0]. The natural convection

A. Abidi; L. Kolsi; M. N. Borjini; H. Ben Aissia

2011-01-01

76

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

NASA Technical Reports Server (NTRS)

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

Plante, Ianik; Wu, Honglu

2014-01-01

77

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

E-print Network

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

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

2000-01-01

78

Underestimation of solar global and diffuse radiation measured at Earth's surface  

NASA Astrophysics Data System (ADS)

Climate change perspectives intensified investigations of the radiative balance of the Earth-atmosphere system. At the top of the atmosphere, solar irradiance is known with absolute uncertainty of 0.3% and theoretical models agree with albedo measurements, but solar shortwave radiation observations at Earth's surface are less than those calculated by radiative-transfer models. This model observation discrepancy (10-25 Wm-2) led to a decade-long controversy on unexplained enhanced absorption of shortwave radiation in clear sky atmospheres as well as in clouds. Here we show evidence for underestimation of surface shortwave irradiance by traditional "unconditioned" global and diffuse pyranometer measurements. Reinvestigations of pyranometer calibration in conjunction with thermal offsets and pyranometer thermal control demonstrate an underestimation of clear sky solar global, as well as diffuse irradiance by 8-20 Wm-2, caused by pyranometer differential cooling. Field measurements with "conditioned" and "unconditioned" pyranometers demonstrate that the so-called night offset is present and considerably larger during daytime measurements, and this not only for diffuse but also for global pyranometer measurements. Long-term comparisons between traditional unconditioned and well-conditioned pyranometer measurements at Davos (midlatitude, 1580 m a.s.l.) show differences of several percent on the annual mean of global irradiance. Even though we are aware that measurements at higher altitudes are subject to larger thermal offsets and not representative for the global average, the results of our experiment lead us to believe that surface solar irradiance, measured in the past throughout the globe by traditional unconditioned pyranometers, is underestimated.

Philipona, Rolf

2002-11-01

79

A comparison between modeled and measured clear-sky radiative shortwave fluxes in Arctic environments, with special emphasis on diffuse radiation  

NASA Astrophysics Data System (ADS)

The ability of the Santa Barbara Disort Atmospheric Radiative Transfer (SBDART) model to predict clear-sky diffuse and direct normal broadband shortwave irradiances is investigated. Model calculations of these quantities are compared with data from the Atmospheric Radiation Measurement program's Southern Great Plains (SGP) and North Slope of Alaska (NSA) sites. The model tends to consistently underestimate the direct normal irradiances at both sites by about 1%. In regard to clear-sky diffuse irradiance, the model overestimates this quantity at the SGP site in a manner similar to what has been observed in other studies [, 2000]. The difference between the diffuse SBDART calculations and Halthore and Schwartz's MODTRAN calculations is very small, thus demonstrating that SBDART performs similarly to MODTRAN. SBDART is then applied to the NSA site, and here it is found that the discrepancy between the model calculations and corrected diffuse measurements (corrected for daytime offsets) [, 2001] is 0.4 W/m2 when averaged over the 12 cases considered here. Two cases of diffuse measurements from a shaded "black and white" pyranometer are also compared with the calculations and the discrepancy is again minimal. Thus, it appears as if the "diffuse discrepancy" that exists at the SGP site does not exist at the NSA sites. We cannot yet explain why the model predicts diffuse radiation well at one site but not at the other.

Barnard, J. C.; Powell, D. M.

2002-10-01

80

Short-term changes in Jupiter's synchrotron radiation at 325 MHz: Enhanced radial diffusion in Jupiter's radiation belt driven by solar UV/EUV heating  

NASA Astrophysics Data System (ADS)

The total flux density of Jupiter's synchrotron radiation (JSR) at 325 MHz was observed in 2007 with the Iitate Planetary Radio Telescope to investigate short-term variations in Jupiter's radiation belt with a time scale of a few days to a month. The total flux density showed a series of short-term increases and subsequent decreases. The variations in JSR and the Mg II solar UV/EUV index showed positive correlations, but the variations in JSR were preceded by those of the Mg II index by 3-5 days. The positive correlation supports a theoretical prediction that an enhancement in the radial diffusion driven by thermospheric winds in the upper atmosphere causes changes in relativistic electron distributions in both the radiation belt and the total flux density of JSR. The radial diffusion model was used to examine the hypothesis that temporal changes in the radial diffusion rate could be an origin of the short-term variation. The model includes physical processes such as radial diffusion, energy degradation by the synchrotron radiation, and several loss processes. We applied a radial diffusion coefficient of 3 × 10-8 L3/s and found a suitable solution that accounted for both the time scale of the short-term variations and the 4 day time lag. The model also showed that strong electron loss processes other than the synchrotron radiation are needed to explain the electron distribution in low L regions. An empirical electron distribution model showed that the synchrotron radiation does not act as a loss of electrons in such areas.

Tsuchiya, F.; Misawa, H.; Imai, K.; Morioka, A.

2011-09-01

81

Radiation therapy  

MedlinePLUS

... Because radiation is most harmful to quickly growing cells, radiation therapy damages cancer cells more than normal cells. This ... cells from growing and dividing, and leads to cell death. Radiation therapy is used to fight many types of cancer . ...

82

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

NASA Astrophysics Data System (ADS)

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

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

83

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

PubMed Central

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

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

2014-01-01

84

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

NASA Technical Reports Server (NTRS)

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 L(sub 1) 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 L(sub 1) (L(sub 1) is approximately equal to 20-50) varies linearly with the square root of the solar wind ram pressure, f is approximately (N(sub s)nu(exp 2 sub s))(exp 1/2). The calculations were carried out with a diffusion coefficient D(sub LL) = D(sub n)L(exp n) with n = 3. The diffusion coefficient which best fit the observed variations in Jupiter's synchrotron radiation D(sub 3) = 1.3 +/- 0.2 x 10(exp -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, Imke; Goertz, Christoph K.

1994-01-01

85

Ionizing radiation  

NASA Technical Reports Server (NTRS)

The penetrating ionizing space radiations are found to be extremely diverse in the energy range of both their particulate and their electromagnetic components. Radiation terms and measures and ionizing radiation classes and sources are presented. Whole body radiation effects are examined, including radiation intensity and rate effectiveness factors. Radiation effects on specific body systems, such as blood, skin, visual, and reproductive systems are also discussed.

Warren, S.; Grahn, D.

1973-01-01

86

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

NASA Astrophysics Data System (ADS)

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

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

2012-10-01

87

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

88

An experimental and theoretical study of radiative extinction of diffusion flames  

NASA Technical Reports Server (NTRS)

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

Wichman, Indrek S.; Atreya, A.

1994-01-01

89

Diffusion of fission products and radiation damage in SiC  

NASA Astrophysics Data System (ADS)

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

Malherbe, Johan B.

2013-11-01

90

Quasi-linear Theory, Nonlinear Wave-Particle Interactions, and Diffusion in the Radiation Belts  

NASA Astrophysics Data System (ADS)

It is well-known that chorus waves can be large in amplitude and narrow in frequency, which is expected to invalidate the quasi-linear treatment of their effects on radiation belt electrons. Interactions can be described as phase bunching (PB) or phase trapping (PT); PB is more likely, and typically leads to abrupt energy and pitch angle decrease, while PT is rare but leads to sustained energy and PA increase. Here we refine the treatment of these processes, investigate how they combine, and consider whether the net result can be treated as diffusion.

Albert, J.

2013-12-01

91

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.

92

Radiation Emergencies  

MedlinePLUS

Radiation is a type of energy. People are exposed to small amounts of radiation every day from sources such as sunlight. A radiation emergency would involve larger amounts of radiation and could be caused by Dirty bombs - a mix of explosives with ...

93

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

94

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

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

95

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

96

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

NASA Astrophysics Data System (ADS)

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

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

97

The asymptotic diffusion limit of continuous and discrete steady-state multigroup radiative transfer problems  

SciTech Connect

The authors consider a linear steady-state multigroup, radiative transfer problem in which the opacities are large [O({epsilon}{sup {minus}1})] and interior sources are small [ O({epsilon})]. An asymptotic analysis of this problem as {epsilon} {r_arrow} 0 leads to a one-group diffusion equation (related to the equilibrium diffusion equation) in the interior of the system, plus boundary conditions for this equation. The same asymptotic analysis of a fully discrete version [S{sub N} in angle, Simple Comer Balance (SCB) in space] of the problem leads to an accurate discretized version of the continuous asymptotic diffusion problem. In other words, as {epsilon} {r_arrow} 0, the SCB scheme limits to an accurate discretization of the continuous asymptotic one-group diffusion equation, and the corresponding boundary conditions are also accurate. This happens even though the optical thickness of the spatial cells tends to {infinity}. The authors analysis shows the following: if a spatial grid is chosen that resolves the material temperature, then an accurate SCB solution is obtained in the interior of the system, even though the spatial grid is optically thick and boundary layers in the transpose solution are not resolved.

Adams, M.L. [Texas A& M Univ., College Station, TX (United States); Larsen, E.W. [Univ. of Michigan, Ann Arbor, MI (United States); Nowak, P.F. [Lawrence Livermore National Lab., CA (United States)

1995-12-31

98

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

99

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

SciTech Connect

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

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

2004-10-01

100

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

101

A grey diffusion acceleration method for time-dependent radiative transfer calculations  

SciTech Connect

The equations of thermal radiative transfer describe the emission, absorption and transport of photons in a material. As photons travel through the material they are absorbed and re-emitted in a Planckian distribution characterized by the material temperature. As a result of these processes, the material can change resulting in a change in the Planckian emission spectrum. When the coupling between the material and radiation is strong, as occurs when the material opacity or the time step is large, standard iterative techniques converge very slowly. As a result, nested iterative algorithms have been applied to the problem. One algorithm, is to use multifrequency DSA to accelerate the convergence of the multifrequency transport iteration and a grey transport acceleration (GTA) followed by a single group DSA. Here we summarize a new method which uses a grey diffusion equation (GDA) to directly solve the multifrequency transport (S{sub N}) problem. Results of Fourier analysis for both the continuous and discretized equations are discussed and the computational efficiency of GDA is compared with the DSA and GTA nested algorithms. 5 refs., 1 fig., 1 tab.

Nowak, P.F.

1991-07-01

102

A multigrid Newton-Krylov method for multimaterial equilibrium radiation diffusion  

SciTech Connect

The authors focus on a fully implicit, nonlinearly converged, solution of multimaterial equilibrium radiation diffusion problems. The nonlinear method of solution is a Newton-Krylov (generalized minimum residual, GMRES) method preconditioned by a multigrid method. The multigrid iteration matrix results from a Picard-type linearization of the governing equations. The governing equation is highly nonlinear with the principal forms of nonlinearity found in the fourth-order dependence of the radiation energy on temperature, the temperature dependence of the opacity, and flux limiting. The efficiency of both the linear and nonlinear iterative techniques is investigated. With the realistic time step control the solution of the linear system does not scale linearly with multigrid as might be expected from theory. In contrast, the authors find that the use of multigrid to precondition a Newton-Krylov (GMRES) method provides a robust, scalable solution for the nonlinear system. Also only through converging the nonlinearities within a time step does the solution method achieve its design accuracy.

Rider, W.J.; Knoll, D.A.; Olson, G.L. [Los Alamos National Lab., NM (United States)] [Los Alamos National Lab., NM (United States)

1999-06-10

103

A new ray-tracing scheme for 3D diffuse radiation transfer on highly parallel architectures  

E-print Network

We present a new numerical scheme to solve the transfer of diffuse radiation on three-dimensional mesh grids which is efficient on processors with highly parallel architecture such as recently popular GPUs and CPUs with multi- and many-core architectures. The scheme is based on the ray-tracing method and the computational cost is proportional to $N_{\\rm m}^{5/3}$ where $N_{\\rm m}$ is the number of mesh grids, and is devised to compute the radiation transfer along each light-ray completely in parallel with appropriate grouping of the light-rays. We find that the performance of our scheme scales well with the number of adopted CPU cores and GPUs, and also that our scheme is nicely parallelized on a multi-node system by adopting the multiple wave front scheme, and the performance scales well with the amount of the computational resources. As numerical tests to validate our scheme and to give a physical criterion for the angular resolution of our ray-tracing scheme, we perform several numerical simulations of the...

Tanaka, Satoshi; Okamoto, Takashi; Hasegawa, Kenji

2014-01-01

104

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

NASA Astrophysics Data System (ADS)

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

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

2014-04-01

105

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

NASA Astrophysics Data System (ADS)

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

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

2014-01-01

106

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

107

Underestimation of solar global and diffuse radiation measured at Earth's surface  

Microsoft Academic Search

Climate change perspectives intensified investigations of the radiative balance of the Earth-atmosphere system. At the top of the atmosphere, solar irradiance is known with absolute uncertainty of 0.3% and theoretical models agree with albedo measurements, but solar shortwave radiation observations at Earth's surface are less than those calculated by radiative-transfer models. This model observation discrepancy (10-25 Wm-2) led to a

Rolf Philipona

2002-01-01

108

Stochastic models of diffusion-controlled ionic reactions in radiation-induced spurs. 1. High-permittivity solvents  

Microsoft Academic Search

Alternative theories for the kinetics of diffusion-controlled reactions between ions in radiation-induced spurs are considered for solvents of high permittivity, such as water. A Monte-Carlo (MC) technique for simulating the paths of the diffusing ions and their encounters is developed and shown to provide an accurate description of the time-dependent reaction probability for the case of a single pair, by

Peter. Clifford; Nicholas J. B. Green; Michael J. Pilling; Simon M. Pimblott

1987-01-01

109

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

110

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

SciTech Connect

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, E-mail: m.s.mohamed@durham.ac.uk [School of Engineering and Computing Sciences, University of Durham, South Road, Durham DH1 3LE (United Kingdom); Seaid, Mohammed; Trevelyan, Jon [School of Engineering and Computing Sciences, University of Durham, South Road, Durham DH1 3LE (United Kingdom)] [School of Engineering and Computing Sciences, University of Durham, South Road, Durham DH1 3LE (United Kingdom); Laghrouche, Omar [Institute for Infrastructure and Environment, Heriot-Watt University, Edinburgh EH14 4AS (United Kingdom)] [Institute for Infrastructure and Environment, Heriot-Watt University, Edinburgh EH14 4AS (United Kingdom)

2013-10-15

111

Impacts of Diffuse Radiation on Light Use Efficiency across Terrestrial Ecosystems Based on Eddy Covariance Observation in China  

PubMed Central

Ecosystem light use efficiency (LUE) is a key factor of production models for gross primary production (GPP) predictions. Previous studies revealed that ecosystem LUE could be significantly enhanced by an increase on diffuse radiation. Under large spatial heterogeneity and increasing annual diffuse radiation in China, eddy covariance flux data at 6 sites across different ecosystems from 2003 to 2007 were used to investigate the impacts of diffuse radiation indicated by the cloudiness index (CI) on ecosystem LUE in grassland and forest ecosystems. Our results showed that the ecosystem LUE at the six sites was significantly correlated with the cloudiness variation (0.24?R2?0.85), especially at the Changbaishan temperate forest ecosystem (R2?=?0.85). Meanwhile, the CI values appeared more frequently between 0.8 and 1.0 in two subtropical forest ecosystems (Qianyanzhou and Dinghushan) and were much larger than those in temperate ecosystems. Besides, cloudiness thresholds which were favorable for enhancing ecosystem carbon sequestration existed at the three forest sites, respectively. Our research confirmed that the ecosystem LUE at the six sites in China was positively responsive to the diffuse radiation, and the cloudiness index could be used as an environmental regulator for LUE modeling in regional GPP prediction. PMID:25393629

Huang, Kun; Wang, Shaoqiang; Zhou, Lei; Wang, Huimin; Zhang, Junhui; Yan, Junhua; Zhao, Liang; Wang, Yanfen; Shi, Peili

2014-01-01

112

Involvement of the anterior thalamic radiation in boys with high functioning autism spectrum disorders: A Diffusion Tensor Imaging study  

Microsoft Academic Search

Background: Autism has been hypothesized to reflect neuronal disconnection. Several recent reports implicate the key thalamic relay nuclei and cortico-thalamic connectivity in the pathophysiology of autism. Accordingly, we aimed to focus on evaluating the integrity of the thalamic radiation and sought to replicate prior white matter findings in Korean boys with high-functioning autism spectrum disorders (ASD) using Diffusion Tensor Imaging

Keun-Ah Cheon; Young-Shin Kim; Se-Hong Oh; Sung-Yeon Park; Hyo-Woon Yoon; John Herrington; Aarti Nair; Yun-Joo Koh; Dong-Pyo Jang; Young-Bo Kim; Bennett L. Leventhal; Zang-Hee Cho; F. Xavier Castellanos; Robert T. Schultz

2011-01-01

113

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

NASA Astrophysics Data System (ADS)

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

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

2014-02-01

114

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

115

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

116

Quantifying Radial Diffusion of Radiation Belt Electrons Based on Global MHD Simulation Validated by GOES and THEMIS Measurements  

NASA Astrophysics Data System (ADS)

Radial diffusion is one of the most important acceleration mechanisms for radiation belt electrons, which is due to the drift-resonant interactions with large-scale fluctuations of the magnetosphere's magnetic and electric fields (Pc4 and Pc5 ranges of ULF waves). A key step in radial diffusion simulations is to quantify the radial diffusion coefficient, which is related to the power spectral density and global mode structure of the ULF waves. However, difficulties in determining the global properties of ULF waves have guided researchers towards specifying empirical forms of the diffusion coefficient, introducing additional uncertainties in the radiation belt studies. In order to quantify the radial diffusion, we run the global MHD simulations to obtain the mode structure and power spectrum of the ULF waves and validate the simulation results with available satellite measurements, such as GOES and THEMIS measurements. The calculated diffusion coefficient is shown to be dominated by the contribution from magnetic field perturbations, and much less from the electric field perturbations. Fast diffusion is found to generally occur when solar wind dynamic pressure is high or nightside geomagnetic activity is strong and with faster diffusion at higher L regions.

Tu, W.; Elkington, S. R.; Li, X.; Liu, W.

2011-12-01

117

Radiation Chemistry  

NASA Astrophysics Data System (ADS)

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

Wojnárovits, L.

118

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

119

Radiation Oncogenesis  

PubMed Central

Two patients who were treated with therapeutic doses of ionizing radiation for primary carcinoma of the thyroid and cervix developed a second malignancy in the organs included in the field of radiation 10 and 14 years later, respectively. These two patients, whose second malignancies meet all of the criteria to be classified as radiation induced cancer, are presented. ImagesFigure 1Figure 2Figure 3Figure 4Figure 5Figure 6Figure 7 PMID:7392087

Kumar, P.P.; Newland, J.R.

1980-01-01

120

Chlorine Diffusion in Uranium Dioxide: Thermal Effects versus Radiation Enhanced Effects  

SciTech Connect

Chlorine is present as an impurity in the UO{sub 2} nuclear fuel. {sup 35}Cl is activated into {sup 36}Cl by thermal neutron capture. In case of interim storage or deep geological disposal of the spent fuel, this isotope is known to be able to contribute significantly to the instant release fraction because of its mobile behavior and its long half life (around 300000 years). It is therefore important to understand its migration behavior within the fuel rod. During reactor operation, chlorine diffusion can be due to thermally activated processes or can be favoured by irradiation defects induced by fission fragments or alpha decay. In order to decouple both phenomena, we performed two distinct experiments to study the effects of thermal annealing on the behaviour of chlorine on one hand and the effects of the irradiation with fission products on the other hand. During in reactor processes, part of the {sup 36}Cl may be displaced from its original position, due to recoil or to collisions with fission products. In order to study the behavior of the displaced chlorine, {sup 37}Cl has been implanted into sintered depleted UO{sub 2} pellets (mean grain size around 18 {mu}m). The spatial distribution of the implanted and pristine chlorine has been analyzed by SIMS before and after treatment. Thermal annealing of {sup 37}Cl implanted UO{sub 2} pellets (implantation fluence of 10{sup 13} ions.cm{sup -2}) show that it is mobile from temperatures as low as 1273 K (E{sub a}=4.3 eV). The irradiation with fission products (Iodine, E=63.5 MeV) performed at 300 and 510 K, shows that the diffusion of chlorine is enhanced and that a thermally activated contribution is preserved (E{sub a}=0.1 eV). The diffusion coefficients measured at 1473 K and under fission product irradiation at 510 K are similar (D = 3.10{sup -14} cm{sup 2}.s{sup -1}). Considering in first approximation that the diffusion length L can be expressed as a function of the diffusion coefficient D and time t by : L=(Dt)1/2, the diffusion distance after 3 years is L=17 {mu}m. It results that there is a great probability for the chlorine contained in the UO{sub 2} grains to have reached the grain boundaries after 3 years, in the core of the fuel rod as well as at its periphery. Moreover, diffusion and concentration of chlorine at grain boundaries has been evidenced using SIMS mapping. Our results indicate therefore, that, during reactor operation and after, the majority of {sup 36}Cl is likely to have moved to grain boundaries, rim and gap. This fraction might then significantly contribute to the rapid or instant release of chlorine. This could have important consequences for safety assessment. During reactor operation, chlorine ({sup 35}Cl), an impurity of the nuclear fuel, is activated into {sup 36}Cl, a long lived mobile isotope. Because of its long half life and its mobility, this isotope may contribute significantly to the instant release fraction under disposal conditions. Thermal annealing of Cl implanted UO{sub 2} sintered pellets show that it is mobile from temperatures as low as 1273 K (E{sub a} = 4.3 eV). Chlorine diffusion induced by irradiation with fission products preserves a thermally activated contribution. The radiation induced defects significantly enhance chlorine migration. (authors)

Pipon, Yves; Moncoffre, Nathalie; Bererd, Nicolas; Jaffrezic, Henri [Universite de Lyon / Universite Claude Bernard Lyon 1 / IUT A Chimie, CNRS/IN2P3/IPNL, 4 rue Enrico Fermi, Villeurbanne, 69622 (France); Toulhoat, Nelly [Universite de Lyon / Universite Claude Bernard Lyon 1 / IUT A Chimie, CNRS/IN2P3/IPNL, 4 rue Enrico Fermi, Villeurbanne, 69622 (France)]|[Commissariat a l'Energie Atomique, DEN, CEN Saclay, Gif sur Yvette cedex, 91191 (France); Barthe, Marie France; Desgardin, Pierre [CNRS, Centre d'Etudes et de Recherches par Irradiation, 3A rue de la Ferollerie Orleans cedex2, 45071 (France); Raimbault, Louis [Ecole des Mines, Centre d'Informatique Geologique (CIG), 35 rue Saint Honore, Fontainebleau cedex, 77305 (France); Scheidegger, Andre M. [Paul Scherrer Institut, Nuclear Energy and Safety Department (NES), Laboratory for Waste Management, Villigen, 5235 (Switzerland); Carlot, Gaelle [Commissariat a l'Energie Atomique, DEN/DEC/SESC/LLCC, Centre de Cadarache, Saint Paul lez Durance, 13108 (France)

2007-07-01

121

Comptonization of diffuse ambient radiation by a relativistic jet: The source of gamma rays from blazars?  

NASA Technical Reports Server (NTRS)

Recent Energy Gamma Ray Experiment Telescope (EGRET) observations of blazars have revealed strong, variable gamma-ray fluxes with no signatures of gamma-ray absorption by pair production. This radiation probably originates from the inner parts of relativistic jets which are aimed nearly toward us. On sub-parsec scales, the jet will be pervaded by radiation from the broad-line region, as well as by photons from the central continuum source (some of which will be scattered by thermal plasma). In a frame moving with the relativistic outflow, the energy of this ambient radiation would be enhanced. This radiation would be Comptonized by both cold and relativistic electrons in the jet, yielding (in the observer's frame) a collimated beam of X-rays and gamma rays. On the assumption that this process dominates self-Comptonization of synchrotron radiation, we develop a self-consistent model for variable gamma-ray emission, involving a single population of relativistic electrons accelerated by a disturbance in the jet. The spectral break between the X-ray and gamma-ray band, observed in 3C 279 and deduced for other blazars, results from inefficient radiative cooling of lower energy electrons. The existence of such a break strongly favors a model involving Comptonization of an external radiation field over a synchrotron self-Compton model. We derive constraints on such model parameters as the location and speed of the source, its dimensions and internal physical parameters, the maximum photon energies produced in the source, and the density and distribution of ambient radiation. Finally, we discuss how observations might discriminate between our model and alternative ones invoking Comptonization of ambient radiation.

Sikora, Marek; Begelman, Mitchell C.; Rees, Martin J.

1994-01-01

122

The diffusion-synthetic acceleration of transport iterations, with application to a radiation hydrodynamics problem  

NASA Astrophysics Data System (ADS)

New numerical methods for solving time-dependent radiative transfer problems in emitting media are described. Three aspects of the solution methods are treated in detail: the time dependence, the intimate coupling between the radiation field and the medium, and the iteration acceleration of the equation of transfer. Iterative procedures for solving the equation of transfer, to which terms from the energy balance equation have been adjoined, are first described, followed by a specific problem in radiative hydrodynamics. The effect of the choice of time steps and iteration convergence on solution accuracy is discussed.

Alcouffe, R. E.; Clark, B. A.; Larsen, E. W.

123

Radiation Therapy  

MedlinePLUS

... the radiation treatment, he or she marks it with ink. This "tattoo" should not be wiped off because these spots ... throat can get sore, which can be treated with a type of mouthwash prescribed ... wear off. For a kid getting radiation therapy, it's normal to feel a ...

124

Ionizing radiation  

NASA Technical Reports Server (NTRS)

The biological effects of ionizing radiation encountered in space are considered. Biological experiments conducted in space and some experiences of astronauts during space flight are described. The effects of various levels of radiation exposure and the determination of permissible dosages are discussed.

Tobias, C. A.; Grigoryev, Y. G.

1975-01-01

125

Radiation Detection  

Microsoft Academic Search

Most radiation related to nuclear properties is outside the visible part of the electromagnetic spectrum or involves submicroscopic particles, hence is invisible. Detectors - devices to sense the radiation, and perhaps measure its properties - are essential. The emphasis in research has moved from the characterization of radioactivity, through simple nuclear reactions, to explorations of the extremes of nuclear matter,

H. C. Griffin

2011-01-01

126

Radiation Exposure  

MedlinePLUS

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

127

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.

128

Perturbative theory of grazing-incidence diffuse nuclear resonant scattering of synchrotron radiation  

SciTech Connect

Theoretical description of off-specular grazing-incidence nuclear resonant scattering of synchrotron radiation (synchrotron Moessbauer reflectometry, SMR) is presented. The recently developed SMR, similar to polarized neutron reflectometry (PNR), is an analytical tool for the determination of isotopic and magnetic structure of thin films and multilayers. It combines the sensitivity of Moessbauer spectroscopy to hyperfine interactions and the depth selectivity of x-ray reflectometry. Specular reflection provides information on the depth profile, while off-specular scattering on the lateral structure of scattering layers. Off-specular SMR and PNR intensity formulas of a rather general multilayer with different domains, based on a distorted incident-wave approximation (DIWA), are presented. The distorted-wave Born approximation results are given in an appendix. Physical and numerical implications, of using DIWA are explained. The temporal character of SMR imposes specific differences between SMR and PNR. In order to reveal the limits of DIWA and to compare the two analytical methods, two-dimensional diffuse SMR and PNR maps of an antiferromagnetic multilayer are calculated and critically compared. Experimental ''{omega}-2{theta}'' SMR map of a periodic [Fe/Cr]{sub 20} multilayer is presented and compared with simulations by the present theory.

Deak, L.; Bottyan, L.; Nagy, D. L. [KFKI Research Institute for Particle and Nuclear Physics, P.O. Box 49, H-1525 Budapest (Hungary); Spiering, H. [Institut fuer Anorganische und Analytische Chemie, Johannes Gutenberg Universitaet Mainz, Staudinger Weg 9, D-55099 Mainz (Germany); Khaidukov, Yu. N. [Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, 141980 Dubna, Moscow Region (Russian Federation); Yoda, Y. [SPring-8 JASRI, 1-1-1 Kouto, Mikazuki-cho, Sayo-gun, Hyogo 679-5198 (Japan)

2007-12-01

129

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

SciTech Connect

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

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

2012-07-01

130

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

NASA Technical Reports Server (NTRS)

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

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

1973-01-01

131

Radiation Belt Radial Diffusion Coefficients Derived From Ground-based and In-situ ULF Wave Measurements  

NASA Astrophysics Data System (ADS)

Ultra Low Frequency (ULF) wave power in the Pc5 period band is thought to play an important role in the dynamics, acceleration and transport of energetic electrons in the outer radiation belt. Current estimates of radial diffusion coefficients are typically derived empirically and characterised in terms of Kp. Using the results from a statistical analysis of ground-based and in-situ electric- and magnetic field power spectral densities as a function of solar wind speed, MLT and L-shell we compile statistical representations for the transport under a diffusive approximation. Electric diffusion rates are calculated using ground-based data from the CARISMA magnetometer network and mapped into in-situ equatorial electric fields using the Ozeke et al. [2009] model. These diffusion rates are compared to those derived from the THEMIS satellites and from previously published CRRES estimates. We find an excellent comparison between the ground-based estimates and in-situ observations. Interestingly the ground-based Pc5 power spectra show evidence of mHz spectral power peaks consistent with those observed on CRRES, and consistent with a role for field line resonances in radial diffusion. We further calculate the magnetic diffusion coefficients using data from THEMIS and GOES, and compare with previous AMPTE estimates. Overall such analysis provides a wave power based method for calculating diffusive transport using observed wave fields. Future in-situ radiation belt missions such as the Canadian Space Agency Outer Radiation Belt Injection, Transport, Acceleration and Loss Satellite (ORBITALS) will enable these physics-based models to be tested and will provide an excellent complement to the single point measurements available from the satellites.

Mann, I. R.; Rae, J.; Ozeke, L.; Murphy, K. R.; Milling, D. K.; Chan, A. A.; Elkington, S. R.

2010-12-01

132

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

133

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

134

The diffusion-synthetic acceleration of transport iterations, with application to a radiation hydrodynamics problem.  

NASA Astrophysics Data System (ADS)

Radiation hydrodynamics treats the interactions of thermal radiation with matter. The matter is generally modeled as a fluid of electrons and ions whose motion is governed by the equations of hydrodynamics. The solution of time-dependent radiative transfer problems in emitting media involves an equation with seven independent variables for the radiation field itself, along with additional equations describing the mass, momentum, and energy balance of the underlying medium. The authors describe new numerical methods of solving such problems. They treat, in detail, three aspects of the solution method: the time dependence, the intimate coupling between the radiation field and the medium, and the iteration acceleration of the equation of transfer. The time dependence is treated implicitly; that is, the equation of transfer is written in terms of the dependent variables evaluated at the advanced time. The solution within each time step is obtained by iteration; the use of an acceleration method, which generates this solution with a convergence rate independent of the time step, is the main focus of this paper. The numerical method outlined here is applied to specific problems in radiation hydrodynamics.

Alcouffe, R. E.; Clark, B. A.; Larsen, E. W.

135

Validity of reduced radiation dose for localized diffuse large B-cell lymphoma showing a good response to chemotherapy.  

PubMed

To evaluate the validity of a decrease in the radiation dose for patients who were good responders to chemotherapy for localized diffuse large B-cell lymphoma (DLBCL), 91 patients with localized DLBCL who underwent radiotherapy after multi-agent chemotherapy from 1988-2008 were reviewed. Exclusion criteria were as follows: central nervous system or nasal cavity primary site, or Stage II with bulky tumor (?10 cm). Of these patients, 62 were identified as good responders to chemotherapy. They were divided into two groups receiving either a higher or a lower radiation dose (32-50.4 Gy or 15-30.6 Gy, respectively). There were no statistically significant differences between the lower and higher dose groups in progression-free survival, locoregional progression-free survival or overall survival. Adaptation of decreased radiation dose may be valid for localized DLBCL patients who show a good response to chemotherapy. PMID:24187329

Koiwai, Keiichiro; Sasaki, Shigeru; Yoshizawa, Eriko; Ina, Hironobu; Fukazawa, Ayumu; Sakai, Katsuya; Ozawa, Takesumi; Matsushita, Hirohide; Kadoya, Masumi

2014-03-01

136

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

PubMed

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

Yamada, Noboru; Okamoto, Kazuya

2014-01-13

137

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

138

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

SciTech Connect

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

Nikitin, A. M., E-mail: am.nikitin@physics.msu.ru [Moscow State University (Russian Federation); Borisov, M. M.; Mukhamedzhanov, E. Kh.; Kovalchuk, M. V. [National Research Center Kurchatov Institute (Russian Federation); Sajti, S.; Tancziko, F.; Deak, L.; Bottyan, L. [Hungarian Academy of Sciences, KFKI Research Institute for Particle and Nuclear Physics (Hungary); Khaydukov, Yu. N.; Aksenov, V. L. [Moscow State University (Russian Federation)

2011-09-15

139

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

140

Radiation dosimeter  

DOEpatents

A radiation detector readout circuit is provided which produces a radiation dose-rate readout from a detector even though the detector output may be highly energy dependent. A linear charge amplifier including an output charge pump circuit amplifies the charge signal pulses from the detector and pumps the charge into a charge storage capacitor. The discharge rate of the capacitor through a resistor is controlled to provide a time-dependent voltage which when integrated provides an output proportional to the dose-rate of radiation detected by the detector. This output may be converted to digital form for readout on a digital display.

Fox, Richard J. (Oak Ridge, TN)

1983-01-01

141

Radiation dosimeter  

DOEpatents

A radiation detector readout circuit is provided which produces a radiation dose-rate readout from a detector even through the detector output may be highly energy dependent. A linear charge amplifier including an output charge pump circuit amplifies the charge signal pulses from the detector and pumps the charge into a charge storage capacitor. The discharge rate of the capacitor through a resistor is controlled to provide a time-dependent voltage which when integrated provides an output proportional to the dose-rate of radiation detected by the detector. This output may be converted to digital form for readout on a digital display.

Fox, R.J.

1981-09-01

142

Evaluating radiation-induced white matter changes in patients treated with stereotactic radiosurgery using diffusion tensor imaging: a pilot study.  

PubMed

Stereotactic radiosurgery (SRS) has been an effective treatment method for brain tumors; however, few data are available regarding radiation-induced white matter (WM) damage by SRS. In this work, diffusion tensor imaging (DTI) was used to investigate WM changes following SRS. Fifteen patients with gliomas were enrolled, with prescription doses ranging 18-25 Gy. Patients were scanned with magnetic resonance imaging (MRI) including DTI before and after SRS. Diffusion tensors were calculated and fiber tracking was performed. Non-irradiated WM volumes and irradiated WM volumes receiving ? 12 Gy and ? Gy were contoured as volumes of interest (VOI). Apparent diffusion coefficient (?D?), fractional anisotropy (FA) and number of fibers (NF) were calculated and assessed using the Wilcoxon signed-rank test. Compared with those of non-irradiated VOIs, FA and NF decreased considerably after two months of SRS in the irradiated WM VOIs. The variation in (?D? was however small and was not statistically significant. The preliminary results suggested that FA and NF might potentially be more sensitive indicators than (?D? in measuring radiation-induced WM changes and DTI could be a valuable tool to assess radiation-induced WM changes in SRS. Although it is still preliminary, this pilot study may be useful to provide insights for future studies. PMID:23862743

Chang, Zheng; Kirkpatrick, John P; Wang, Zhiheng; Cai, Jing; Adamson, Justus; Yin, Fang-Fang

2014-02-01

143

Radiation damage  

E-print Network

a) Radiation damage in organic materials. This series of lectures will give an overview of radiation effects on materials and components frequently used in accelerator engineering and experiments. Basic degradation phenomena will be presented for organic materials with comprehensive damage threshold doses for commonly used rubbers, thermoplastics, thermosets and composite materials. Some indications will be given for glass, scintillators and optical fibres. b) Radiation effects in semiconductor materials and devices. The major part of the time will be devoted to treat radiation effects in semiconductor sensors and the associated electronics, in particular displacement damage, interface and single event phenomena. Evaluation methods and practical aspects will be shown. Strategies will be developed for the survival of the materials under the expected environmental conditions of the LHC machine and detectors. I will describe profound revolution in our understanding of black holes and their relation to quantum me...

Heijne, Erik H M; CERN. Geneva

1998-01-01

144

Radiation Therapy  

MedlinePLUS

Donate Donate One Time Monthly Event Tribute For brain tumor information and support Call: 800-886-ABTA (2282) ... Donate Now Menu Treatment & Care Continuum of Care Brain Tumor Treatments Steroids Surgery Chemotherapy Radiation Stereotactic Radiosurgery Proton ...

145

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

146

Erratum: "Anomalous Diffuse Interstellar Bands in the Spectrum of Herschel 36. II. Analysis of Radiatively Excited CH+, CH, and Diffuse Interstellar Bands" (2013, ApJ, 773, 42)  

NASA Astrophysics Data System (ADS)

Absorption spectra toward Herschel 36 for the A^1Pi <-- X^1Sigma transitions of CH+ in the J=1 excited rotational level and the A^2Delta <-- X^2Pi transition of CH in the J=3/2 excited fine structure level have been analyzed. These excited levels are above their ground levels by 40.1 K and ~25.7 K and indicate high radiative temperatures of the environment, 14.6 K and 6.7 K, respectively. The effect of the high radiative temperature is more spectacular in some diffuse interstellar bands (DIBs) observed toward Her 36; remarkable extended tails toward red (ETR) were observed. We interpret these ETRs as due to a small decrease of rotational constants upon excitation of excited electronic states. Along with radiative pumping of a great many high-J rotational levels, this causes the ETRs. In order to study this effect quantitatively, we have developed a model calculation in which the effects of collision and radiation are treated simultaneously. The simplest case of linear molecules is considered. It has been found that the ETR is reproduced if the fraction of the variation of the rotational constant, beta = (B'-B)/B, is sufficiently high (3-5%) and the radiative temperature is high (T_r > 50 K). Although modeling for general molecules is beyond the scope of this paper, the results indicate that the prototypical DIBs at 5780.5, 5797.1, and 6613.6 A which show the pronounced ETRs are due to polar molecules sensitive to the radiative excitation. The requirement of high beta favors relatively small molecules with 3-6 heavy atoms. DIBs at 5849.8, 6196.0, and 6379.3 A which do not show the pronounced ETRs are likely due to non-polar molecules or large polar molecules with small beta.

Oka, Takeshi; Welty, Daniel E.; Johnson, Sean; York, Donald G.; Dahlstrom, Julie; Hobbs, Lew

2014-09-01

147

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 ...

148

Monte Carlo simulation of diffusion and reaction in radiation-induced spurs. Comparisons with analytic models  

Microsoft Academic Search

Reaction in radiation-induced spurs, containing one type of radical, is simulated by using random walks on a cubic lattice. The simulations are shown to agree satisfactorily with analytical results for the evolution of a single-particle density function and for the reaction between two particles. For spurs containing more than two particles, no exact analytical treatments are available. Results of simulations

Peter Clifford; Nicholas J. B. Green; Michael J. Pilling

1982-01-01

149

Anterior thalamic radiation integrity in schizophrenia: A diffusion-tensor imaging study  

Microsoft Academic Search

The anterior limb of the internal capsule (ALIC) is a white matter structure, the medial portion of which includes the anterior thalamic radiation (ATR) carrying nerve fibers between thalamus and prefrontal cortex. ATR abnormalities have a possible link with cognitive abnormalities and negative symptoms in schizophrenia. We aimed to study the fiber integrity of the ATR more selectively by isolating

Daniel Mamah; Thomas E. Conturo; Michael P. Harms; Erbil Akbudak; Lei Wang; Amanda R. McMichael; Mokhtar H. Gado; Deanna M. Barch; John G. Csernansky

2010-01-01

150

Radiation enteritis and radiation scoliosis  

SciTech Connect

Any patient with radiation scoliosis should be suspected of having a visceral lesion as well. Chronic radiation enteritis may be manifested by intestinal obstruction, fistulas, perforation, and hemorrhage. Intestinal obstruction is the most common complication, and must be differentiated from postoperative cast or from spinal-traction syndrome. Obstruction that does not respond promptly to conservative measures must be treated surgically. Irradiated bowel is ischemic, and necrosis with spontaneous perforation can only be avoided with early diagnosis and surgical intervention.

Shah, M.; Eng, K.; Engler, G.L.

1980-09-01

151

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

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

152

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

153

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

154

Optic Radiation Fiber Tractography in Glioma Patients Based on High Angular Resolution Diffusion Imaging with Compressed Sensing Compared with Diffusion Tensor Imaging - Initial Experience  

PubMed Central

Objective Up to now, fiber tractography in the clinical routine is mostly based on diffusion tensor imaging (DTI). However, there are known drawbacks in the resolution of crossing or kissing fibers and in the vicinity of a tumor or edema. These restrictions can be overcome by tractography based on High Angular Resolution Diffusion Imaging (HARDI) which in turn requires larger numbers of gradients resulting in longer acquisition times. Using compressed sensing (CS) techniques, HARDI signals can be obtained by using less non-collinear diffusion gradients, thus enabling the use of HARDI-based fiber tractography in the clinical routine. Methods Eight patients with gliomas in the temporal lobe, in proximity to the optic radiation (OR), underwent 3T MRI including a diffusion-weighted dataset with 30 gradient directions. Fiber tractography of the OR using a deterministic streamline algorithm based on DTI was compared to tractography based on reconstructed diffusion signals using HARDI+CS. Results HARDI+CS based tractography displayed the OR more conclusively compared to the DTI-based results in all eight cases. In particular, the potential of HARDI+CS-based tractography was observed for cases of high grade gliomas with significant peritumoral edema, larger tumor size or closer proximity of tumor and reconstructed fiber tract. Conclusions Overcoming the problem of long acquisition times, HARDI+CS seems to be a promising basis for fiber tractography of the OR in regions of disturbed diffusion, areas of high interest in glioma surgery. PMID:23923036

Kuhnt, Daniela; Bauer, Miriam H. A.; Sommer, Jens; Merhof, Dorit; Nimsky, Christopher

2013-01-01

155

Radiation Detection  

NASA Astrophysics Data System (ADS)

Most radiation related to nuclear properties is outside the visible part of the electromagnetic spectrum or involves submicroscopic particles, hence is invisible. Detectors - devices to sense the radiation, and perhaps measure its properties - are essential. The emphasis in research has moved from the characterization of radioactivity, through simple nuclear reactions, to explorations of the extremes of nuclear matter, but the central importance of suitable radiation detectors has persisted. This chapter emphasizes detectors associated with measurements of radioactivity, as opposed to nuclear reactions. Thus, much of the current creative work is excluded, but otherwise the scope of these volumes would at least double. Detectors are classified broadly as based on ionization of gases, conduction in semiconductors, or scintillation. The concluding section is an introduction to systems based on two or more components of one of these basic types.

Griffin, H. C.

156

Quantitative volumetric analysis of the optic radiation in the normal human brain using diffusion tensor magnetic resonance imaging-based tractography  

PubMed Central

To attain the volumetric information of the optic radiation in normal human brains, we performed diffusion tensor imaging examination in 13 healthy volunteers. Simultaneously, we used a brain normalization method to reduce individual brain variation and increase the accuracy of volumetric information analysis. In addition, tractography-based group mapping method was also used to investigate the probability and distribution of the optic radiation pathways. Our results showed that the measured optic radiation fiber tract volume was a range of about 0.16% and that the fractional anisotropy value was about 0.53. Moreover, the optic radiation probability fiber pathway that was determined with diffusion tensor tractography-based group mapping was able to detect the location relatively accurately. We believe that our methods and results are helpful in the study of optic radiation fiber tract information.

Lee, Dong-Hoon; Park, Ji-Won; Hong, Cheol-Pyo

2014-01-01

157

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

158

Radiation Fog  

NSDL National Science Digital Library

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

Comet

1999-12-10

159

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

SciTech Connect

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

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

2013-02-01

160

Appendix G. Radiation Appendix G. Radiation  

E-print Network

-made sources. People are exposed to naturally occurring radiation constantly. For example, cosmic radiationAppendix G. Radiation #12;#12;Appendix G. Radiation This appendix presents basic facts about radiation. The information is intended to be a basis for un- derstanding the potential doses associated

Pennycook, Steve

161

Radiation Insulation  

NASA Technical Reports Server (NTRS)

Radiation insulation technology from Apollo and subsequent spacecraft was used to develop superinsulators, used by makers of cold weather apparel, to make parkas, jackets, boots and outdoor gear such as sleeping bags. The radiant barrier technology offers warmth retention at minimal weight and bulk.

1987-01-01

162

Radiation Activities  

NSDL National Science Digital Library

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

2013-07-17

163

Radiation damage  

NASA Technical Reports Server (NTRS)

The radiation damage workshop considered a variety of topics among which were the need for equivalent electron fluences in gallium arsenide, the possibility of 15 percent end-of-life efficiencies for silicon, increasing radiation resistance in gallium arsenide, annealing of radiation damage and the need for radiation damage studies in cascade cells. The workshop members agreed that a high priority should be assigned to obtaining equivalent electron fluences for gallium arsenide cells. It was suggested that 1 MeV would be a reasonable electron energy for this purpose. Special care should be given to proton irradiations particularly for energies below 1 MeV. In addition, omnidirectional rather than normal incidence protons should be used. It was also agreed that there was a need for obtaining damage coefficients in gallium arsenide. In silicon, there is a requirement for additional flight data, especially in proton dominated orbits. These data are needed to further check the accuracy of the 1 MeV equivalence fluences.

Weinberg, I.

1982-01-01

164

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

SciTech Connect

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

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

2014-01-01

165

SOLAR RADIATION AND URBAN HEAT ISLANDS  

Microsoft Academic Search

A model which attempts to simulate urban absorption of solar radiation is concerned with direct solar radiation, diffuse sky radiation, diffuse radiation reflected by buildings and streets, and the shortwave energy absorbed by typical urban structures. The ratio between solar radiation absorbed by three-dimensional building-street systems and two-dimensional horizontal surfaces under cloudless conditions indicates that cities undergo great variations with

WERNER H. TERJUNG; STELLA S. F. LOUIE

1973-01-01

166

ANOMALOUS DIFFUSE INTERSTELLAR BANDS IN THE SPECTRUM OF HERSCHEL 36. II. ANALYSIS OF RADIATIVELY EXCITED CH{sup +}, CH, AND DIFFUSE INTERSTELLAR BANDS  

SciTech Connect

Absorption spectra toward Herschel 36 (Her 36) for the A-bar{sup 1}{Pi} Leftwards-Open-Headed-Arrow X-tilde{sup 1}{Sigma} transitions of CH{sup +} in the J = 1 excited rotational level and for the A-bar{sup 2}{Delta} Leftwards-Open-Headed-Arrow X-tilde{sup 2}{Pi} transitions of CH in the J = 3/2 excited fine structure level have been analyzed. These excited levels are above their ground levels by 40.1 K and {approx}25.7 K and indicate high radiative temperatures of the environment of 14.6 K and 6.7 K, respectively. The effect of the high radiative temperature is more spectacular in some diffuse interstellar bands (DIBs) observed toward Her 36; remarkable extended tails toward red (ETRs) were observed. We interpret these ETRs as being due to a small decrease of the rotational constants upon excitation of the excited electronic states. Along with radiative pumping of a great many high-J rotational levels, this causes the ETRs. In order to study this effect quantitatively, we have developed a model calculation in which the effects of collisions and radiation are treated simultaneously. The simplest case of linear molecules is considered. It has been found that the ETR is reproduced if the fraction of the variation of the rotational constant, {beta} {identical_to} (B' - B)/B, is sufficiently high (3%-5%) and the radiative temperature is high (T{sub r} > 50 K). Although modeling for general molecules is beyond the scope of this paper, the results indicate that the prototypical DIBs {lambda}5780.5, {lambda}5797.1, and {lambda}6613.6 which show the pronounced ETRs are due to polar molecules that are sensitive to the radiative excitation. The requirement of high {beta} favors relatively small molecules with three to six heavy atoms. DIBs {lambda}5849.8, {lambda}6196.0, and {lambda}6379.3 that do not show the pronounced ETRs are likely due to non-polar molecules or large polar molecules with small {beta}.

Oka, Takeshi; Welty, Daniel E.; Johnson, Sean; York, Donald G.; Hobbs, L. M. [Department of Astronomy and Astrophysics, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637 (United States); Dahlstrom, Julie, E-mail: t-oka@uchicago.edu [Department of Physics and Astronomy, Carthage College, 2001 Alford Park Drive, Kenosha, WI 53140 (United States)

2013-08-10

167

Radiation Oncology Treatment Team  

MedlinePLUS

... Prostate Skin Upper GI Latest Research Find a Radiation Oncologist Last Name: Facility: City: State: Zip Code: ... who specializes in using radiation to treat cancer . Radiation Oncologists Radiation oncologists are the doctors who will ...

168

Acute Radiation Syndrome  

MedlinePLUS

... Tools CDC Response, Japan 2011 Specific Hazards Acute Radiation Syndrome (ARS): A Fact Sheet for the Public ... is called the radiation dose. People exposed to radiation will get ARS only if: The radiation dose ...

169

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

NASA Technical Reports Server (NTRS)

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

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

1999-01-01

170

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

171

Radiation Belts  

NSDL National Science Digital Library

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

Stern, David

172

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

173

Fundamental Radiation Concepts  

E-print Network

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

Slatton, Clint

174

Non-diffusive resonant acceleration of electrons in the radiation belts  

SciTech Connect

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

Artemyev, A. V.; Krasnoselskikh, V. V.; Agapitov, O. V. [LPC2E/CNRS, University of Orleans, Orleans (France); Mourenas, D. [CEA, DAM, DIF, F-91297 Arpajon (France); Rolland, G. [CNES, Toulouse (France)

2012-12-15

175

RADIATION SAFETY TRAINING MANUAL Radiation Safety Office  

E-print Network

RADIATION SAFETY TRAINING MANUAL Radiation Safety Office 130 DeSoto Street G-7 Parran@pitt.edu Internet: www.radsafe.pitt.edu Trainman911.wpd Revised 9/11 #12;FOREWORD All personnel who are working protection and the potential risks of ionizing radiation. Radiation Safety Office personnel provide

Sibille, Etienne

176

Shortwave Radiation  

NASA Technical Reports Server (NTRS)

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

Klassen, Steve; Bugbee, Bruce

2005-01-01

177

[Solar cosmic radiation and the radiation hazard of space flight].  

PubMed

Present-day data on the spectrum of solar radiation in the source and near the Earth are discussed as applied to the radiation safety of crewmembers and electronics onboard manned and unmanned spacecraft. It is shown that the slope of the solar radiation spectrum changes (flattens) in the low energy range. Quantitative information about absolute solar radiation fluxes near the Earth is summarized in relation to the most significant flares of 1956--1978. The time-related evolution of the solar radiation spectrum in the interplanetary space is described in quantitative terms (as illustrated by the solar flare of 28 September 1961). It is indicated that the nonmonotonic energy dependence of the transport path of solar radiation in the interplanetary space should be taken into consideration. It is demonstrated that the diffusion model of propagation can be verified using solar radiation measurements in space flights. PMID:6308342

Miroshnichenko, L I

1983-01-01

178

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

NASA Astrophysics Data System (ADS)

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

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

2010-06-01

179

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

Microsoft Academic Search

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

I. de Pater

1994-01-01

180

Simulation of the outer radiation belt electrons near geosynchronous orbit including both radial diffusion and resonant interaction with Whistler-mode chorus waves  

Microsoft Academic Search

We present the first simulation results for electrons in the outer radiation belt near geosynchronous orbit, where radial diffusion and resonant interactions with whistler-mode chorus outside the plasmasphere are taken into account. Bounce averaged pitch-angle and energy diffusion rates are introduced in the Salammbô code for L <= 6.5, for electron energies between 10 keV and 3 MeV and fpe\\/fce

Athena Varotsou; Daniel Boscher; Sebastien Bourdarie; Richard B. Horne; Sarah A. Glauert; Nigel P. Meredith

2005-01-01

181

Radiation Insulation  

NASA Technical Reports Server (NTRS)

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

1993-01-01

182

Radiation Insulation  

NASA Technical Reports Server (NTRS)

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

1995-01-01

183

Radiation dosimeters  

DOEpatents

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

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

1992-01-01

184

Radiation Safety September 2013  

E-print Network

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

California at Irvine, University of

185

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

NASA Technical Reports Server (NTRS)

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

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

1993-01-01

186

RADIATION SAFETY OFFICE UNIVERSITYOF MARYLAND  

E-print Network

RADIATION SAFETY OFFICE UNIVERSITYOF MARYLAND RADIATION SAFETY MANUAL UNIVERSITY OF MARYLAND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.2. Radiation Safety Committee (RSC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1.4. Radiation Safety Office (RSO

Rubloff, Gary W.

187

Radiation from Relativistic Jets  

NASA Technical Reports Server (NTRS)

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

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

2008-01-01

188

Dosimetry of space radiations  

NASA Technical Reports Server (NTRS)

Harmful effects of space radiation are discussed. Radiation dosimetry methods are given. Dosimetry monitoring is investigated. Methods for measuring space radiation by ionization, thermoluminescence, and nuclear photographic emulsions are described.

Arkhangelskiy, V. V.; Markelov, V. V.; Skvortsov, S. S.; Smirennyy, L. N.; Turkin, V. N.; Chernykh, I. V.

1973-01-01

189

Radiation Contamination Versus Exposure  

MedlinePLUS

RADIATION CONTAMINATION VERSUS EXPOSURE EXTERNAL CONTAMINATION External contamination occurs when radioactive material comes into contact with a ... radioactive materials can accumulate in different body organs. RADIATION EXPOSURE Another word for radiation exposure is irradiation. ...

190

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

SciTech Connect

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

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

2010-10-28

191

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

E-print Network

/Myr. There is no correlation between helium diffusion and apatite chemistry including F/Cl ratio, but the closure temperature] is a proxy for a sample's natural exposure to actinide radioactivity below the closure temperature. This relies on the assertion that the physical mechanisms responsible for laboratory observations are exactly

Shuster, David L.

192

HYDRODYNAMIC LIMITS FOR KINETIC EQUATIONS AND THE DIFFUSIVE APPROXIMATION OF RADIATIVE  

E-print Network

hypothesis (h1), the mass u satisfies the conservation law tu + div X a()f d = 0, (h2) guarantees that (1 equations equipped with a single conservation law which generate L1 -contractions. We discuss the hydrodynamic limit to a scalar conservation law and the diffusive limit to a (possibly) degenerate parabolic

Tzavaras, Athanasios E.

193

Hazard calculations of diffuse reflected laser radiation for the SELENE program  

NASA Technical Reports Server (NTRS)

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

Miner, Gilda A.; Babb, Phillip D.

1993-01-01

194

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

NASA Technical Reports Server (NTRS)

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

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

1974-01-01

195

SAS-2 observations of the diffuse gamma radiation in the galactic latitude interval from 10 to 90 deg in both hemispheres  

NASA Technical Reports Server (NTRS)

An analysis of all the second Small Astronomy Satellite (SAS-2) gamma-ray data for galactic latitudes higher than 10 deg in both hemispheres has shown that the intensity varies with galactic latitude, being larger near 10 deg than 90 deg. For energies above 100 MeV the gamma-ray data are consistent with a latitude distribution of the form I(b) = C1 + C2/sin b, with the second term being dominant. This result suggests that the radiation above 100 MeV is coming largely from local regions of the galactic disk. Between 35 and 100 MeV, a similar equation is also a good representation of the data, but here the two terms are comparable. These results indicate that the diffuse radiation above 35 MeV consists of two parts, one with a relatively hard galactic component and the other an isotropic steep spectral component which extrapolates back well to the low-energy (less than 10 MeV) diffuse radiation. The steepness of the diffuse isotropic component places significant constraints on possible theoretical models of this radiation.

Fichtel, C. E.; Hartman, R. C.; Kniffen, D. A.; Thompson, D. J.; Ogelman, H. B.; Ozel, M. E.; Tumer, T.

1977-01-01

196

3D radiation belt diffusion model results using new empirical models of whistler chorus and hiss  

NASA Astrophysics Data System (ADS)

3D diffusion codes model the energization, radial transport, and pitch angle scattering due to wave-particle interactions. Diffusion codes are powerful but are limited by the lack of knowledge of the spatial & temporal distribution of waves that drive the interactions for a specific event. We present results from the 3D DREAM model using diffusion coefficients driven by new, activity-dependent, statistical models of chorus and hiss waves. Most 3D codes parameterize the diffusion coefficients or wave amplitudes as functions of magnetic activity indices like Kp, AE, or Dst. These functional representations produce the average value of the wave intensities for a given level of magnetic activity; however, the variability of the wave population at a given activity level is lost with such a representation. Our 3D code makes use of the full sample distributions contained in a set of empirical wave databases (one database for each wave type, including plasmaspheric hiss, lower and upper hand chorus) that were recently produced by our team using CRRES and THEMIS observations. The wave databases store the full probability distribution of observed wave intensity binned by AE, MLT, MLAT and L*. In this presentation, we show results that make use of the wave intensity sample probability distributions for lower-band and upper-band chorus by sampling the distributions stochastically during a representative CRRES-era storm. The sampling of the wave intensity probability distributions produces a collection of possible evolutions of the phase space density, which quantifies the uncertainty in the model predictions caused by the uncertainty of the chorus wave amplitudes for a specific event. A significant issue is the determination of an appropriate model for the spatio-temporal correlations of the wave intensities, since the diffusion coefficients are computed as spatio-temporal averages of the waves over MLT, MLAT and L*. The spatiotemporal correlations cannot be inferred from the wave databases. In this study we use a temporal correlation of ~1 hour for the sampled wave intensities that is informed by the observed autocorrelation in the AE index, a spatial correlation length of ~100 km in the two directions perpendicular to the magnetic field, and a spatial correlation length of 5000 km in the direction parallel to the magnetic field, according to the work of Santolik et al (2003), who used multi-spacecraft measurements from Cluster to quantify the correlation length scales for equatorial chorus . We find that, despite the small correlation length scale for chorus, there remains significant variability in the model outcomes driven by variability in the chorus wave intensities.

Cunningham, G.; Chen, Y.; Henderson, M. G.; Reeves, G. D.; Tu, W.

2012-12-01

197

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

198

Radiation monitoring system  

Microsoft Academic Search

A radiation monitoring system which continuously detects and measures ; low levels of radiation and radioactive materials in the surrounding atmosphere ; comprises a large volume multiple scintillation beta radiation detector wiih an ; alpha particulate radiation scintillation detector, and with backgrtound ; reduction being achieved by the use of an anti-coincidence cosmic ray and high ; energy photon shield.

Battist

1973-01-01

199

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

200

Radiation Critical Readiness Review  

NASA Technical Reports Server (NTRS)

This slide presentation reviews the radiation preparedness and radiation monitors on the International Space Station (ISS). It includes information on the Tissue Equivalent Proportional Counter (TEPC), Radiation Area Monitors, Extra-Vehicular Charged Particle Directional Spectrometer (EV-CPDS), and the space radiation analysis group.

Misek, William

2010-01-01

201

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

NASA Astrophysics Data System (ADS)

In this study we perform a reanalysis of the sparse MEA CRRES relativistic electron data using a relatively simple one-dimensional radial diffusion model and a Kalman filtering approach. By combining observations with the model in an optimal way we produce a high time and space resolution reanalysis of the radiation belt electron fluxes over a 50-d period starting on 18 August 1990. The results of the reanalysis clearly show pronounced peaks in the electron phase space density (PSD), which can not be explained by the variations in the outer boundary, and can only be produced by a local acceleration processes. The location of the innovation vector shows that local acceleration is most efficient at L* = 5.5 for electrons at K = 0.11 G0.5 R E and ? = 700 MeV/G. Sensitivity numerical experiments for various values of ? and K indicate that peaks in PSD become stronger with increasing K and ?. To verify that our results are not affected by the limitations of the satellite orbit and coverage, we performed an ``identical twin'' experiments with synthetic data specified only at the locations for which CRRES observations are available. Our results indicate that the model with data assimilation can accurately reproduce the underlying structure of the PSD even when data is sparse. The identical twin experiments also indicate that PSD at a particular L-shell is determined by the local processes and cannot be accurately estimated unless local measurements are available.

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

2007-12-01

202

Dynamics of radiating fluids  

SciTech Connect

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

Mihalas, D.; Weaver, R.

1982-01-01

203

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

2012-01-01

204

Treatment of diffuse in-stent restenosis with rotational atherectomy followed by radiation therapy with a rhenium-188–mercaptoacetyltriglycine-filled balloon  

Microsoft Academic Search

OBJECTIVESThis study was done to evaluate the feasibility and efficacy of beta-radiation therapy with a rhenium-188–mercaptoacetyltriglycine (188Re-MAG3)-filled balloon after rotational atherectomy for diffuse in-stent restenosis (ISR).BACKGROUNDRotational atherectomy has been shown to be safe and efficient for the treatment of ISR, but the recurrence rate is still high. Intracoronary beta-irradiation after rotational atherectomy may be a reasonable approach to prevent recurrent

Seong-Wook Park; Myeong-Ki Hong; Dae Hyuk Moon; Seung Jun Oh; Cheol Whan Lee; Jae-Joong Kim; Seung-Jung Park

2001-01-01

205

Management of radiation maculopathy.  

PubMed

Radiation maculopathy is a delayed onset complication of radiation exposure. Various host and radiation parameters determine the risk of developing radiation maculopathy, which may be progressive. Total radiation dose delivered to the macula is the most important modifiable factor. Radiation maculopathy is not a singular entity as clinical manifestations reflect combined effects of all damaged tissues. Current treatment using anti-vascular endothelial growth factor agents offers only a short-term, temporary, and modest visual improvement. Avoidance or prevention of radiation maculopathy may be the best option. Use of periocular steroid during plaque brachytherapy may prevent radiation maculopathy over the short term. Newer designs and techniques of delivering radiation to the eye need to be explored. PMID:22907147

Singh, Arun D; Pabon, Sheila; Aronow, Mary E

2012-01-01

206

Fiber optic radiation sensors  

NASA Astrophysics Data System (ADS)

A survey of fiber-optic sensors for the measurement of ionizing radiation is given. The interactions between ionizing radiation and fiber material, which are of significance for the fiber-optic detection of ionizing radiation, as well as the changes in the properties of the optical fibers induced by such interactions are discussed. Measurement and evaluation techniques for reading out the optical properties induced by ionizing radiation are described. A survey of possible applications for fiber-optic radiation sensors is given. The properties and application possibilities of fiber-optic dosimeters based on radiation-induced losses are specified. In particular, the requirements to be met by fiber-optic dosimeters for applications in radiation therapy are discussed. A fiber-optic dosimeter measuring system for radiation therapy based on radiation-induced losses is presented.

Bueker, Harald; Haesing, Friedrich W.

1994-12-01

207

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.

208

Plutonium radiation surrogate  

DOEpatents

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

Frank, Michael I. (Dublin, CA)

2010-02-02

209

Radiative Accelerations in Stellar Evolution  

E-print Network

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

G. Michaud; J. Richer

2008-01-26

210

What Is Radiation Shielding?  

NASA Video Gallery

Kerry Lee, NASA Orion radiation system manager, explains how radiation shielding is used to block harmful particles coming into the spacecraft without producing secondary particles that can cause e...

211

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

212

The Diffuse Galactic gamma Radiation: The Compton Contribution and Component Separation by Energy Interval and Galactic Coordinates.  

National Technical Information Service (NTIS)

The radiation to be expected from cosmic ray interactions with matter and photons was examined. Particular emphasis is placed on the Compton emission. Both the photon density in and near the visible region and that in the region are deduced from the estim...

D. A. Kniffen, C. E. Fichtel

1981-01-01

213

Dangers of Radiation Exposure  

NSDL National Science Digital Library

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

214

An Improved Radiation Pyrometer  

Microsoft Academic Search

In designing a new radiation pyrometer for industrial use above the lower limit of visible radiation, consideration of ambient temperature effects, which is of much importance in modern industrial practice, was carried out by aid of mathematical analysis. In one hypothetical case, with a very sensitive type of thermopile losing heat from its hot junction by radiation alone, it is

Thos. R. Harrison; Wm. H. Wannamaker

1941-01-01

215

JPL Radiation Effects Facilities  

NASA Technical Reports Server (NTRS)

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

Thorbourn, Dennis

2013-01-01

216

Spacecraft radiator systems  

NASA Technical Reports Server (NTRS)

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

Anderson, Grant A. (Inventor)

2012-01-01

217

Radiation Research Program (RRP)  

Cancer.gov

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

218

Notes on synchrotron radiation  

E-print Network

I comment on a number of theoretical issues related to magnetobremsstrahlung, and especially on synchrotron radiation and Unruh (temperature) radiation, that I consider of importance for the current progress towards a better understanding of the stationary features of such fundamental radiation patterns both in an accelerator context and, more generally, in the physical world

H. C. Rosu

1994-12-11

219

astroph/9507030 Gravitational Radiation  

E-print Network

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

Fygenson, Deborah Kuchnir

220

Cancer-causing radiation  

Microsoft Academic Search

Radiation causes cancer. That simple fact was known by the early 1900s. Further, radiation can induce cancer in almost any tissue in animals and humans. But the cancer-causing dose may vary by 20-fold for different tissues in animals. Such variation is also seen in people who are exposed, typically, to low radiation doses. Hence, the minimum dose that causes human

R. L. Ullrich; J. M. Holland; J. B. Storer

1977-01-01

221

Breaking all the invariants: Anomalous electron radiation belt diffusion by pitch angle scattering in the presence of split magnetic drift shells  

NASA Astrophysics Data System (ADS)

electron observations near geostationary orbit routinely show pitch angle distributions peaked away from 90 degrees. These "butterfly" distributions are consistent with magnetic drift shell splitting combined with a radial flux gradient. During magnetic storms, nature adds pitch angle scattering to split drift shells, breaking all three adiabatic invariants of the particle's motion. Therefore, some degree of anomalous radial diffusion is likely, and cross terms between the gyration and drift invariants and between the bounce and drift invariants arise. Using typical assumptions about the pitch angle scattering and the magnetic field topology, we calculate these anomalous diffusion coefficients near geostationary orbit. We show that the anomalous radial diffusion can exceed that due to more traditional drift-resonant wave-particle interactions. We also show that the neglected cross terms, particularly the bounce-drift cross term, can be significant. These results suggest necessary additions to some global electron radiation belt simulations.

O'Brien, T. P.

2014-01-01

222

Ionizing Radiation: The issue of radiation quality  

NASA Astrophysics Data System (ADS)

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

Prise, Kevin; Schettino, Giuseppe

223

Appendix F: Radiation Appendix F: Radiation F-3  

E-print Network

to naturally occurring radiation constantly. For example, cosmic radiation; radon in air; potassium in foodAppendix F: Radiation #12;#12;Appendix F: Radiation F-3 Fig. F.1. The hydrogen atom and its isotopes. Appendix F: Radiation This appendix presents basic facts about radiation. The information

Pennycook, Steve

224

Appendix F: Radiation Appendix F: Radiation F-3  

E-print Network

. People are exposed to naturally occurring radiation constantly. For example, cosmic radiation; radonAppendix F: Radiation #12;#12;Appendix F: Radiation F-3 P P P E E E N NN HYDROGEN ATOM DEUTERIUM. The hydrogen atom and its isotopes. Appendix F: Radiation This appendix presents basic facts about radiation

Pennycook, Steve

225

Radiative Corrections to Bremsstrahlung in Radiative Return  

E-print Network

Radiating a photon from the initial state provides a useful tool for studying a range of low energy physics using a high-energy e+ e- accelerator. Accurate results require careful calculation of the first order virtual photon corrections. We compare exact results for initial state radiative corrections, finding agreement to an order of 10^{-5} or better as a fraction of the Born cross-section for most of the range of photon energies, at CMS energies relevant in both high-energy collision and radiative return experiments.

Scott A. Yost; S. Jadach; B. F. L. Ward

2005-05-09

226

Radiation Safety Program Annual Review  

E-print Network

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

Lyubomirsky, Ilya

227

Radiation Shielding and Radiological Protection  

E-print Network

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

Shultis, J. Kenneth

228

Solar cell radiation handbook  

NASA Technical Reports Server (NTRS)

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

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

1973-01-01

229

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

230

Radiation protection and instrumentation  

NASA Technical Reports Server (NTRS)

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

Bailey, J. V.

1975-01-01

231

RF radiation from lightning  

NASA Technical Reports Server (NTRS)

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

Levine, D. M.

1978-01-01

232

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

233

Radiation Related Terms Basic Terms  

E-print Network

Radiation Related Terms Basic Terms Radiation Radiation is energy in transit in the form of high not carry enough energy to separate molecules or remove electrons from atoms. Ionizing radiation Ionizing radiation is radiation with enough energy so that during an interaction with an atom, it can remove tightly

Vallino, Joseph J.

234

High-power radiating plasma  

NASA Technical Reports Server (NTRS)

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

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

1984-01-01

235

Simple Waves in Ideal Radiation Hydrodynamics  

SciTech Connect

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

Johnson, B M

2008-09-03

236

Results of 5-year concurrent recordings of global, diffuse, and UV-radiation at three levels (700, 1800, and 3000 m a.s.l.) in the Northern Alps  

NASA Astrophysics Data System (ADS)

Radiation values of the solar spectral range are studied in the mountains (Bavarian Alps) at three neighboring, vertically graduated stations at 740, 1780, and 2964 m a.s.l. Additional to the global radiation, the diffuse radiation from sky and UV-radiation in the range from 310 to 340 nm are recorded. Radiation on a spherical body is measured with Bellani-type pyranometers. Besides the presentation of frequency distributions and daily and annual variations under mean conditions and on clear days, special emphasis was laid on the coherence between the different kinds of radiation and on their dependence from the height above sea level. Finally, the influence of atmospheric parameters is investigated.

Reiter, R.; Munzert, K.; Sladkovic, R.

1982-01-01

237

Three-dimensional diffusion of non-sorbing species in porous sandstone: computer simulation based on X-ray microtomography using synchrotron radiation.  

PubMed

The diffusion pathways of porous sandstone were examined by a three-dimensional (3-D) imaging technique based on X-ray computed tomography (CT) using the SPring-8 (Super Photon ring-8 GeV, Hyogo, Japan) synchrotron radiation facility. The analysis was undertaken to develop better understanding of the diffusion pathways in natural rock as a key factor in clarifying the detailed mechanism of the diffusion of radionuclides and water molecules through the pore spaces of natural barriers in underground nuclear waste disposal facilities. A cylindrical sample (diameter 4 mm, length 6 mm) of sandstone (porosity 0.14) was imaged to obtain a 3-D image set of 450(3) voxels=2.62(3) mm(3). Through cluster-labeling analysis of the 3-D image set, it was revealed that 89% of the pore space forms a single large pore-cluster responsible for macroscopic diffusive transport, while only 11% of the pore space is made up of isolated pores that are not involved in long-range diffusive transport. Computer simulations of the 3-D diffusion of non-sorbing random walkers in the largest pore cluster were performed to calculate the surface-to-volume ratio of the pore, tortuosity (diffusion coefficient in free space divided by that in porous rock). The results showed that (i) the simulated surface-to-volume ratio is about 60% of the results obtained by conventional pulsed-field-gradient proton nuclear magnetic resonance (NMR) laboratory experiments and (ii) the simulated tortuosity is five to seven times larger than the results of laboratory diffusion experiments using non-sorbing I(-) and Br(-). These discrepancies are probably attributed to the intrinsic sample heterogeneity and limited spatial resolution of the CT system. The permeability was also estimated based on the NMR diffusometry theory using the results of the random walk simulations via the Kozeny-Carman equation. The estimated permeability involved an error of about 20% compared with the permeability measured by the conventional method, suggesting that the diffusometry-based NMR well logging with gradient coils is applicable to the in-situ permeability measurement of strata. The present study demonstrated that X-ray CT using synchrotron radiation is a powerful tool for obtaining 3-D pore structure images without the beam-hardening artifacts inevitable in conventional CT using X-ray tubes. PMID:15358495

Nakashima, Yoshito; Nakano, Tsukasa; Nakamura, Koichi; Uesugi, Kentaro; Tsuchiyama, Akira; Ikeda, Susumu

2004-10-01

238

Jet radiation radius  

NASA Astrophysics Data System (ADS)

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

Han, Zhenyu

2014-10-01

239

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

240

Radiation exposure and pregnancy.  

PubMed

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

Labant, Amy; Silva, Christina

2014-01-01

241

Jet Radiation Radius  

E-print Network

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

Zhenyu Han

2014-02-06

242

Earth Radiation Measurement Science  

NASA Technical Reports Server (NTRS)

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

Smith, G. Louis

2000-01-01

243

Alternative application for the radiation background in the development of the atlas database of atmospheric radiation  

E-print Network

Nowadays radiation is one of the variables to be considered in the environmental forecasting and it is meaningful in the increase of global warming, together greenhouse effect. The radiation considered by the meteorological organizations depends on the World Radiometric Reference (WRR), the World Standard Group (WSG), addressed by the World Meteorological Organization (WMO). This work is based on the cosmic microwave background, as a variable to be estimated in order to get information about the incident radiation in the Earth's atmosphere, as a valuable and meaningful contribution in the building of the radiation atlas by the (UPME) and (IDEAM). Due to the fact that the variables considered are ultraviolet and infrared radiation, ozone column, direct radiation and diffuse radiation, the last two get the global radiation, and are the only ones to be evaluated by the national meteorological organizations in the country. The study of the cosmic background radiation as a research project will provide data which ...

De la Hoz, Ivan Arturo Morales

2014-01-01

244

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

245

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

246

BlackBody Radiation  

Microsoft Academic Search

Hot objects give off light and heat in the form of electromagnetic radiation whose character changes with temperature. Black-body\\u000a radiation is such electromagnetic radiation in equilibrium with its material surroundings. By the late 1800s, it was a lively\\u000a research topic for both theoretical and experimental physicists. Samuel Pierpont Langley (1834–1906) in the United States,\\u000a and a group of experimental physicists

Clayton Gearhart; O. Lummer; Annalen der Physik; E. Pringsheim; C. Annalen der Physik

247

Intracranial interstitial radiation  

SciTech Connect

Primary malignant brain tumors are fatal, with 90% of patients having these tumors dying within two years following diagnosis. Cranial interstitial radiation therapy, a technique under investigation to control these tumors, involves implantation of radioactive iodine 125 seeds into the tumor bed by stereotaxic technique. The interstitial radiation technique, monitoring of radiation, and nursing care of patients are discussed. Case histories are presented, along with discussion of results attained using this therapy, and its future.

Willis, D.; Rittenmeyer, H.; Hitchon, P.

1986-06-01

248

US EPA Radiation Protection  

NSDL National Science Digital Library

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

2010-04-05

249

Environmental Radiation Protection  

NASA Astrophysics Data System (ADS)

The environmental distribution of radionuclides, released from nuclear facilities and other sources, and the principles of the emergency countermeasures for radiation protection of the public and workers are discussed in this chapter. The concentration levels of radionuclides in various aquatic and terrestrial environments and the exposure levels of the population due to the various sources of radiation (natural and artificial radionuclides, cosmic radiation, diagnostic medical examinations, atmospheric nuclear tests, etc.) are presented.

Maeda, Y.; Osaki, S.; Vincze, A.

250

Interstitial photon radiation.  

PubMed

Most minimally invasive ablative techniques utilize thermal energies for tissue destruction. However, the heat-sink phenomenon may limit the efficacy of radiofrequency ablation and cryotherapy of tissue near blood vessels. One alternative non-temperature-dependent ablative technique is photon radiation. This radiation is dependent on energy and intensity, and its effects are influenced only by the density of the surrounding tissue. Photon radiation therapy may offer a unique alternative for ablating tissue surrounding vascular structures. PMID:14622484

Chan, David Y; Solomon, Stephen B; Kavoussi, Louis R

2003-10-01

251

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

252

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

253

Radiative accelerations and atomic data requirements  

NASA Astrophysics Data System (ADS)

Radiative accelerations are crucial quantities to study element diffusion in stars. They strongly depend on atomic properties of ions in a way more or less similar to opacities or synthetic spectra. Computations of radiative accelerations however have also some specific requirements which make them very sensitive to the quality of atomic data. We shall present various aspects of the radiative accelerations computations and discuss, through examples, how they are so closely related to the knowledge of atomic data.

Alecian, G.

254

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

NASA Technical Reports Server (NTRS)

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

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

1999-01-01

255

Photosynthetically-active radiation: sky radiance distributions under clear and overcast conditions  

Microsoft Academic Search

The photosynthetically active radiation (PAR), defined as the wavelength band of 0.400 ?m to 0.700 ?m, represents most of the visible solar radiation. Although the proportion of global irradiance that originates from diffuse sky radiation is higher for PAR than for all solar shortwave radiation, it is often assumed that the PAR diffuse sky radiation is distributed identically to that

Richard H. Grant; Gordon M. Heisler; Wei Gao

1996-01-01

256

Radiation coloration resistant glass  

DOEpatents

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

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

1986-01-01

257

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

258

Flexible radiator system  

NASA Technical Reports Server (NTRS)

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

Oren, J. A.

1982-01-01

259

Appendix F. Radiation Appendix F. Radiation F-3  

E-print Network

. For example, cosmic radiation; radon in air; potassium in food and water; and uranium, thorium, and radiumAppendix F. Radiation #12;#12;Appendix F. Radiation F-3 Appendix F. Radiation This appendix presents basic facts about radiation. The information is intended to be a basis for understanding

Pennycook, Steve

260

Appendix G. Radiation Appendix G. Radiation G-3  

E-print Network

. For example, cosmic radiation; radon in air; potassium in food and water; and ura- nium, thorium, and radiumAppendix G. Radiation #12;#12;Appendix G. Radiation G-3 Appendix G. Radiation This appendix presents basic facts about radiation. The information is intended to be a basis for un- derstanding

Pennycook, Steve

261

Appendix F. Radiation Appendix F. Radiation F-3  

E-print Network

. For example, cosmic radiation; radon in air; potassium in food and water; and ura- nium, thorium, and radiumAppendix F. Radiation #12;#12;Appendix F. Radiation F-3 Appendix F. Radiation This appendix presents basic facts about radiation. The information is intended to be a basis for un- derstanding

Pennycook, Steve

262

An Introduction to Radiation General Definition of Radiation  

E-print Network

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

Massey, Thomas N.

263

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

NASA Astrophysics Data System (ADS)

The gas-phase optical absorption spectrum of the thiophenoxy radical (C6H5S), a diffuse interstellar band (DIB) candidate molecule, was observed in the discharge of thiophenol using a cavity ringdown spectrometer. The ground-state rotational constants of the thiophenoxy radical were theoretically calculated, and the excited-state rotational constants were determined from the observed rotational profile. The rotational profile of a near prolate molecule having C 2v symmetry was simulated on the basis of a rotational distribution model by radiation and collisions. Although the simulated profile did not agree with the observed DIBs, the upper limit of the column density for the thiophenoxy radical in the diffuse clouds toward HD 204827 was evaluated to be 2 × 1013 cm–2. The profile simulation indicates that rotational distribution by radiation and collisions is important to reproduce a rotational profile for a DIB candidate and that the near prolate C 2v molecule is a possible candidate for DIB with a band width variation dependent on the line of sight.

Araki, Mitsunori; Niwayama, Kei; Tsukiyama, Koichi

2014-11-01

264

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

265

Ultraviolet-radiation-curable paints  

SciTech Connect

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

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

1981-09-30

266

[Radiobiology and radiation hygiene].  

PubMed

From the analysis of clinical, epidemiological and radiobiological data the radiation effect levels have been determined at which nonstochastic and stochastic effects are or are not displayed during the average life of a human being. The most "noneffective" radiation does have been used in calculating the major dose thresholds of "non-harmful" exposures. PMID:1947029

Buldakov, L A

1991-01-01

267

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

268

Treatment of Radiation Injury  

PubMed Central

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

Akita, Sadanori

2014-01-01

269

Global radiation oncology waybill  

PubMed Central

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

Munoz-Garzon, Victor; Rovirosa, Angeles; Ramos, Alfredo

2013-01-01

270

Peculiarities of Meteor Radiation  

Microsoft Academic Search

In this article the characteristics of radiation of meteors are investigated: the character of a radiating spectrum depends first of all on a speed of a meteor, and also on a chemical and mechanical structure of meteoroid's; the spectrum of a meteor changes along the path of a meteor in an atmosphere according to the law of Wien; for the

V. A. Smirnov

2004-01-01

271

ON THE JITTER RADIATION  

SciTech Connect

In a small-scale turbulent medium, when the nonrelativistic Larmor radius R{sub L} = mc {sup 2}/eB exceeds the correlation length {lambda} of the magnetic field, the magnetic Bremsstrahlung radiation of charged relativistic particles unavoidably proceeds to the so-called jitter radiation regime. The cooling timescale of parent particles is identical to the synchrotron cooling time, thus this radiation regime can be produced with very high efficiency in different astrophysical sources characterized by high turbulence. The jitter radiation has distinct spectral features shifted toward high energies, compared to synchrotron radiation. This effect makes the jitter mechanism an attractive broad-band gamma-ray production channel, which, in highly magnetized and turbulent environments, can compete or even dominate over other high-energy radiation mechanisms. In this paper, we present a novel study of the spectral properties of the jitter radiation performed within the framework of perturbation theory. The derived general expression for the spectral power of radiation is presented in a compact and convenient form for numerical calculations.

Kelner, S. R. [Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1, D-6917 Heidelberg (Germany); Aharonian, F. A. [Dublin Institute for Advanced Studies, 31 Fitzwilliam Place, Dublin 2 (Ireland); Khangulyan, D., E-mail: skelner@rambler.ru, E-mail: Felix.Aharonian@mpi-hd.mpg.de, E-mail: khangul@astro.isas.jaxa.jp [Institute of Space and Astronautical Science/JAXA, 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210 (Japan)

2013-09-01

272

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

273

Ultraviolet radiation changes  

NASA Technical Reports Server (NTRS)

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

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

1991-01-01

274

Radiation-induced pneumothorax  

SciTech Connect

Pneumothorax is an uncommon complication of radiation therapy to the chest. The proposed pathogenesis is radiation-induced fibrosis promoting subpleural bleb formation that ruptures resulting in pneumothorax. We report on two young patients with primary sarcomas without pulmonary metastases who developed spontaneous pneumothorax after irradiation. Neither patient had antecedent radiographic evidence of pulmonary fibrosis.

Epstein, D.M.; Littman, P.; Gefter, W.B.; Miller, W.T.; Raney, R.B. Jr.

1983-01-01

275

Radiation Processing -an overview  

E-print Network

1 Radiation Processing - an overview Arne Miller Risø High Dose Reference Laboratory Risø DTU DK irradiation · Material modification #12;3 Content ­ Part 2 · Environmental applications · Other applications ­ radiation hardness testing ­ semiconductors ­ microlitography ­ gem stones · Dosimetry · Quality assurance

276

Radiative forcing by contrails  

Microsoft Academic Search

A parametric study of the instantaneous radiative impact of contrails is presented using three diÄerent radiative transfer models for a series of model atmospheres and cloud parameters. Contrails are treat- ed as geometrically and optically thin plane parallel homogeneous cirrus layers in a static atmosphere. The ice water content is varied as a function of ambient temperature. The model atmospheres

R. Meerkotter; U. Schumann; D. R. Doelling; P. Minnis; T. Nakajima; Y. Tsushima

1999-01-01

277

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.

278

Radiation therapy simulation workbook  

SciTech Connect

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

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

1986-01-01

279

Radiation detection system  

DOEpatents

A radiation detection system including a radiation-to-light converter and fiber optic wave guides to transmit the light to a remote location for processing. The system utilizes fluors particularly developed for use with optical fibers emitting at wavelengths greater than about 500 nm and having decay times less than about 10 ns.

Franks, Larry A. (Santa Barbara, CA); Lutz, Stephen S. (Santa Barbara, CA); Lyons, Peter B. (Los Alamos, NM)

1981-01-01

280

Radiatively inefficient accretion disks  

E-print Network

Radiatively inefficient (or advection dominated) disks are discussed at an introductory level. Ion supported and radiation supported flows are discussed, the different consequences of advection dominated flows onto black holes vs. solid surfaces (neutron stars, white dwarfs), hydrodynamics, the role of the ratio of specific heats, and the possible connection between ADAFs and outflows.

H. C. Spruit

2000-03-10

281

Gallbladder Cancer: Radiation Therapy  

MedlinePLUS

... reducing side effects. Three-dimensional conformal radiation therapy (3D-CRT): 3D-CRT is a type of external beam radiation ... therapy (IMRT) : IMRT is an advanced form of 3D therapy. It uses a computer-driven machine that ...

282

Forecasting Radiation Fog  

NSDL National Science Digital Library

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

Comet

2002-02-04

283

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

284

Ultrasensitive Human Radiation Dosimetry  

NASA Technical Reports Server (NTRS)

The problem we are addressing concerns the astronauts, and their exposure to radiation during spaceflight. The amount of this radiation is a variable depending on solar events and orbital characteristics. Our goal is to measure the total integrated quantity of radiation damage to the cell nucleus in astronauts or other people exposed to radiation. In my lab, we are turning up the microscope from the level of the chromosome, about eight orders of magnitude, to the molecular level. It is well known that radiation causes DNA and chromosome damage. We are developing methods to measure a specific molecular lesion. The lesion that we have selected to measure is thymidine diol, which is created by hydroxyl radicals adding across the 5.6 double bond of thymidine in DNA.

Hammen, Richard

1985-01-01

285

Radiative relativistic shock adiabate  

SciTech Connect

The influences of thermal radiation on the state equation of shock waves, derived in the previous paper [L. N. Tsintsadze, Phys. Plasmas {bold 2}, 4462 (1995)], are studied and a series of relations of thermodynamic quantities that hold for shock waves are derived. It is shown that the presence of radiation can strongly change the compressibility of the plasma. It is well known that for polytropic gases the compressibility cannot change more than four times the initial value in the case of nonrelativistic temperatures. The numerical calculations show that there are no such restrictions, when the radiation energy exceeds the kinetic energy of the plasma. The ultrarelativistic temperature range is also covered in our numerical calculations. Also studied are the influences of the radiation on the PT and the TV diagrams. A significant modification due to radiation is found in every case studied. {copyright} {ital 1997 American Institute of Physics.}

Tsintsadze, L.N.; Nishikawa, K. [Faculty of Science, Hiroshima University, Higashihiroshima-City 1739 (Japan)] [Faculty of Science, Hiroshima University, Higashihiroshima-City 1739 (Japan)

1997-03-01

286

Broadband optical radiation detector  

NASA Technical Reports Server (NTRS)

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

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

1981-01-01

287

Radiation Induced Genomic Instability  

PubMed Central

Radiation induced genomic instability can be observed in the progeny of irradiated cells multiple generations after irradiation of parental cells. The phenotype is well established both in vivo (Morgan 2003) and in vitro (Morgan 2003), and may be critical in radiation carcinogenesis (Little 2000, Huang et al. 2003). Instability can be induced by both the deposition of energy in irradiated cells as well as by signals transmitted by irradiated (targeted) cells to non-irradiated (non-targeted) cells (Kadhim et al. 1992, Lorimore et al. 1998). Thus both targeted and non-targeted cells can pass on the legacy of radiation to their progeny. However the radiation induced events and cellular processes that respond to both targeted and non-targeted radiation effects that lead to the unstable phenotype remain elusive. PMID:21556289

Morgan, William F.

2011-01-01

288

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

289

Deployable Heat Pipe Radiator  

NASA Technical Reports Server (NTRS)

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

Edelstein, F.

1975-01-01

290

RADIATION SAFETY MANUAL POLICIES AND PROCEDURES  

E-print Network

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

Zhang, Yuanlin

291

Solar radiation for Mars power systems  

NASA Technical Reports Server (NTRS)

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

Appelbaum, Joseph; Landis, Geoffrey A.

1991-01-01

292

[Remote radiation planning support system].  

PubMed

We constructed a remote radiation planning support system between Kyushu University Hospital (KUH) in Fukuoka and Kyushu University Beppu Hospital (KBH) in Oita. Between two institutions, radiology information system for radiotherapy division (RT-RIS) and radiation planning system (RTPS) were connected by virtual private network (VPN). This system enables the radiation oncologists at KUH to perform radiotherapy planning for the patients at KBH. The detail of the remote radiation planning support system in our institutions is as follows: The radiation oncologist at KBH performs radiotherapy planning and the data of the patients are sent anonymously to the radiation oncologists at KUH. The radiation oncologists at KUH receive the patient's data, access to RTPS at KBH, verify or change the radiation planning at KBH: Radiation therapy is performed at KBH according to the confirmed plan by the radiation oncologists at KUH. Our remote radiation planning system is useful for providing radiation therapy with safety and accuracy. PMID:23157128

Atsumi, Kazushige; Nakamura, Katsumasa; Yoshidome, Satoshi; Shioyama, Yoshiyuki; Sasaki, Tomonari; Ohga, Saiji; Yoshitake, Tadamasa; Shinoto, Makoto; Asai, Kaori; Sakamoto, Katsumi; Hirakawa, Masakazu; Honda, Hiroshi

2012-08-01

293

Solar radiation on Mars: Update 1991  

NASA Technical Reports Server (NTRS)

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

Appelbaum, Joseph; Landis, Geoffrey A.

1991-01-01

294

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. PMID:23509762

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

2013-01-01

295

Radiative Processes in Astrophysics  

NASA Astrophysics Data System (ADS)

Radiative Processes in Astrophysics: This clear, straightforward, and fundamental introduction is designed to present-from a physicist's point of view-radiation processes and their applications to astrophysical phenomena and space science. It covers such topics as radiative transfer theory, relativistic covariance and kinematics, bremsstrahlung radiation, synchrotron radiation, Compton scattering, some plasma effects, and radiative transitions in atoms. Discussion begins with first principles, physically motivating and deriving all results rather than merely presenting finished formulae. However, a reasonably good physics background (introductory quantum mechanics, intermediate electromagnetic theory, special relativity, and some statistical mechanics) is required. Much of this prerequisite material is provided by brief reviews, making the book a self-contained reference for workers in the field as well as the ideal text for senior or first-year graduate students of astronomy, astrophysics, and related physics courses. Radiative Processes in Astrophysics also contains about 75 problems, with solutions, illustrating applications of the material and methods for calculating results. This important and integral section emphasizes physical intuition by presenting important results that are used throughout the main text; it is here that most of the practical astrophysical applications become apparent.

Rybicki, George B.; Lightman, Alan P.

1986-06-01

296

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

297

Radiative forcing of climate  

NASA Technical Reports Server (NTRS)

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

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

1991-01-01

298

The Intense Radiation Gas  

E-print Network

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

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

2004-10-14

299

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

300

Radiation-induced intradural malignant peripheral nerve sheath tumor of the cauda equina with diffuse leptomeningeal metastasis.  

PubMed

Malignant peripheral nerve sheath tumors (MPNSTs) are rare, affecting only a small portion of the general population. In many cases, MPNSTs occur in association with neurofibromatosis Type 1 and at times arise secondary to previous radiation therapy (RT). These tumors can be found essentially anywhere a peripheral nerve is present, but they rarely originate primarily from the spinal nerve or cauda equina and cause leptomeningeal spread. This report describes the treatment course of a 43-year-old man with a history of testicular seminoma treated with RT a decade before, who was found to have a large sacral MPNST. The patient underwent complete sacrectomy for gross-total resection. Despite this effort, he was eventually found to have metastatic lesions throughout the spine and brain, ultimately resulting in acute hydrocephalus and death. Biopsy results of these metastatic lesions proved to be characteristic of his original MPNST. The literature is also reviewed and the diagnostic modalities, management strategies, and prognosis of MPNST are discussed. PMID:25216401

Lau, Darryl; Moon, Dominic H; Park, Paul; Hervey-Jumper, Shawn; McKeever, Paul E; Orringer, Daniel A

2014-11-01

301

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

302

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

303

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 ...

304

Pregnancy and Radiation Exposure  

MedlinePLUS

... Exposure to the Embryo or Fetus from Diagnostic Nuclear Medicine Pregnant women may be administered radioactive materials ... determination be obtained from the health physicist, a nuclear medicine physician, or a radiation oncologist associated with ...

305

Nanotechnology in radiation oncology.  

PubMed

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

Wang, Andrew Z; Tepper, Joel E

2014-09-10

306

Radiation Physics with Diamonds  

NASA Astrophysics Data System (ADS)

Some salient features and examples of the numerous results obtained during the last decade in close collaboration with Friedel Sellschop in a Bonn/Darmstadt/Erlangen/Kharkov/ Munich/Rossendorf/Wits Collaboration at the superconducting Darmstadt electron linear accelerator (S-DALINAC) on the interaction of relativistic electrons with diamonds are presented. These studies started with investigations of channeling radiation (CR) and were later on extended into the field of parametric X radiation (PXR), with the main aim to possibly develop a tunable radiation source with a small bandwidth. But also basic properties of these types of radiations, like e.g. coherence and occupation lengths, linewidths, polarization and interference with coherent bremsstrahlung have been investigated as well as special properties of diamonds. An example for such a measurement is the susceptibility of diamond through PXR. Lately CR has also been explored in the context of a new acceleration mechanism.

Richter, A.

2001-09-01

307

External Radiation Therapy  

MedlinePLUS Videos and Cool Tools

Narrator: When the cancer is not completely contained in the prostate or when the patient is older the treatment that is frequently used ... There are different forms of radiation for prostate cancer. They really boil down to two different types. ...

308

Photochemistry Radiation and Photolysiss  

E-print Network

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

Toohey, Darin W.

309

Radiation therapy - skin care  

MedlinePLUS

... not swim in pools, salt water, lakes, or ponds. Keep the treatment area out of direct sun ... Czito BG, Willett CG. Radiation injury. In: Feldman M, Friedman LS, ... Liver Disease . 9th ed. Philadelphia, PA: Saunders Elsevier; 2010: ...

310

Nonionizing Radiation 583.  

National Technical Information Service (NTIS)

Lesson plans are provided for a specialty course designed to be used as an introduction to nonionizing radiation including sources, attendant hazards to personnel, and the basic principles of control. Special attention is given to evaluation and control o...

1983-01-01

311

Radiation Tolerant Antifuse FPGA  

NASA Technical Reports Server (NTRS)

The total dose performance of the antifuse FPGA for space applications is summarized. Optimization of the radiation tolerance in the fabless model is the main theme. Mechanisms to explain the variation in different products are discussed.

Wang, Jih-Jong; Cronquist, Brian; McCollum, John; Parker, Wanida; Katz, Rich; Kleyner, Igor; Day, John H. (Technical Monitor)

2002-01-01

312

EM Radiation Program  

NSDL National Science Digital Library

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

Christian, Wolfgang

2008-05-20

313

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...

314

Space radiation studies  

NASA Technical Reports Server (NTRS)

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

Gregory, J. C.

1986-01-01

315

Ionizing radiation detector  

DOEpatents

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

Thacker, Louis H. (Knoxville, TN)

1990-01-01

316

Environmental Radiation Exposures  

Cancer.gov

Atomic Bomb Survivors Semipalatinsk Nuclear Test Site, Kazakhstan Study of Radiation Doses and Cancer Risks Resulting from the 1945 "Trinity" Atomic Weapon Test Thyroid Disease in Young Persons Near Chernobyl Techa River Print This Page Environmental

317

Occupational Radiation Exposures  

Cancer.gov

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

318

Radiation Dose Chart  

NSDL National Science Digital Library

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

Munroe, Randall

319

Radiation-Induced Bioradicals  

NASA Astrophysics Data System (ADS)

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

Lahorte, Philippe; Mondelaers, Wim

320

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

321

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

322

Radiation Safety Manual Dec 2012 Page 1 RADIATION SAFETY  

E-print Network

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

Grishok, Alla

323

The NCI Radiation Research Program: Grant portfolio and radiation  

E-print Network

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

324

Radiation Safety Training Basic Radiation Safety Training for  

E-print Network

Radiation Safety Training Basic Radiation Safety Training for X-ray Users for Physics 461 & 462 Protocol Title: Basic Radiation Safety Training for X-ray Users Drafted By: Chris Millsaps, RSS Reviewers: ZB, TU, GS Purpose: To provide basic radiation safety training to the users of x-ray producing

Dai, Pengcheng

325

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

PubMed Central

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

Lemasson, Benjamin; 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

326

Ducted auroral kilometric radiation  

NASA Technical Reports Server (NTRS)

Certain discrete, intense wave signals attributed to auroral kilometric radiation (AKR) were observed with ISEE-l while it was within the plasmaspheric shadow zone for direct propagation. It is believed that wave ducting by thin depletions of the plasma density aligned with the magnetic field accounts for such signals, and that their discrete nature is caused by the satellite intercepting individual ducts. These ducts, which were also observed as coincident decreases of the upper hybrid resonance frequency, appeared to be twenty-percent depletions roughly one hundred kilometers across. The AKR, which is emitted approximately perpendicular to the magnetic field, apparently entered these ducts equatorward of the source after the waves had been refracted parallel to the duct axis. A diffuse background was also observed which is consistent with the leakage from similar ducts at lower L-values. These observations establish the existence of ducted AKR, its signature on the satellite wave spectrograms, and new evidence for depletion ducts within the plasmasphere.

Calvert, W.

1982-01-01

327

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

328

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

329

Radiation-induced sarcoma  

Microsoft Academic Search

Opinion statement  Radiation-induced sarcomas can originate in either the irradiated bone or soft tissues. Most of these tumors are high-grade.\\u000a The most common histologic subtypes are malignant fibrous histiocytoma (MFH) and osteosarcoma, although other histologies\\u000a (eg, angiosarcoma, rhabdomyosarcoma) can occur. Tumor size and grade are the two most important prognostic factors for soft tissue\\u000a sarcomas, including those associated with radiation therapy.

Shreyaskumar R. Patel

2000-01-01

330

Radiation associated tumors following therapeutic cranial radiation  

PubMed Central

Background: A serious, albeit rare, sequel of therapeutic ionizing radiotherapy is delayed development of a new, histologically distinct neoplasm within the radiation field. Methods: We identified 27 cases, from a 10-year period, of intracranial tumors arising after cranial irradiation. The original lesions for which cranial radiation was used for treatment included: tinea capitis (1), acute lymphoblastic leukemia (ALL; 5), sarcoma (1), scalp hemangioma (1), cranial nerve schwannoma (1) and primary (13) and metastatic (1) brain tumors, pituitary tumor (1), germinoma (1), pinealoma (1), and unknown histology (1). Dose of cranial irradiation ranged from 1800 to 6500 cGy, with a mean of 4596 cGy. Age at cranial irradiation ranged from 1 month to 43 years, with a mean of 13.4 years. Results: Latency between radiotherapy and diagnosis of a radiation-induced neoplasm ranged from 4 to 47 years (mean 18.8 years). Radiation-induced tumors included: meningiomas (14), sarcomas (7), malignant astrocytomas (4), and medulloblastomas (2). Data were analyzed to evaluate possible correlations between gender, age at irradiation, dose of irradiation, latency, use of chemotherapy, and radiation-induced neoplasm histology. Significant correlations existed between age at cranial irradiation and development of either a benign neoplasm (mean age 8.5 years) versus a malignant neoplasm (mean age 20.3; P = 0.012), and development of either a meningioma (mean age 7.0 years) or a sarcoma (mean age 27.4 years; P = 0.0001). There was also a significant positive correlation between latency and development of either a meningioma (mean latency 21.8 years) or a sarcoma (mean latency 7.7 years; P = 0.001). The correlation between dose of cranial irradiation and development of either a meningioma (mean dose 4128 cGy) or a sarcoma (mean dose 5631 cGy) approached significance (P = 0.059). Conclusions: Our study is the first to show that younger patients had a longer latency period and were more likely to have lower-grade lesions (e.g. meningiomas) as a secondary neoplasm, while older patients had a shorter latency period and were more likely to have higher-grade lesions (e.g. sarcomas). PMID:22629485

Chowdhary, Abhineet; Spence, Alex M.; Sales, Lindsay; Rostomily, Robert C.; Rockhill, Jason K.; Silbergeld, Daniel L.

2012-01-01

331

Numerical Radiative Transfer  

NASA Astrophysics Data System (ADS)

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

Kalkofen, Wolfgang

2009-07-01

332

Packet personal radiation monitor  

DOEpatents

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

Phelps, James E. (Knoxville, TN)

1989-01-01

333

Space radiation dosimetry  

SciTech Connect

Dosimetry is the measurement of the energy deposited in matter by various forms of radiation. In space the radiation is primarily energetic electrons, protons and heavier ions from planetary radiation belts, solar flares, and interstellar cosmic rays. Experimentally, dose is frequently obtained by summing the individual energy deposits in a solid state detector. If the detector is calibrated and the sensitive mass is known, the energy sum can be converted directly to accumulated radiation dose in Gy (J/kg). Such detectors can also be used to provide an approximate separation of dose into the components due to electrons, protons, and heavier ions, which is useful if it is desired to convert the measured dose into a biological effective dose (Sv) for manned spaceflight purposes. The output can also be used to provide an essentially instantaneous dose rate for use as warning devices. This is the primary type of space radiation dosimeter to be discussed here. The MOS-type dosimeter is another solid state sensor which can be of small size and low power. These devices integrate the total dose once through, can not separate particle types, and are not suitable for instantaneous dose rate measurement at low levels. There are several additional methods of measuring space radiation dose using scintillators, etc., but are not discussed in detail. In this paper emphasis is given to descriptions of active solid state detector instruments which have successfully worked in space. Some results of in-orbit dose measurements are presented.

Hanser, F.A.; Dichter, B.K. [Armed Forces Radiobiology Research Inst., Bethesda, MD (United States); [DLR Inst. of Aerospace Medicine, Cologne (Germany); [NASA, Goddard Space Flight Center, Greenbelt, MD (United States)

1993-12-31

334

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" li]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

335

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

336

Appendix A: Radiation HYDROGEN ATOM  

E-print Network

. People are exposed to naturally occurring radiation constantly. For example, cosmic radiation; radonAppendix A: Radiation #12;P P P E E E N NN HYDROGEN ATOM DEUTERIUM ATOM TRITIUM ATOM HYDROGEN DEUTERIUM TRITIUM PROTONS NEUTRONS 1 1 1 0 1 2 ORNL-DWG 94M-5236 Appendix A: Radiation A-3 Fig. A.1

Pennycook, Steve

337

Appendix G: Radiation HYDROGEN ATOM  

E-print Network

. People are exposed to naturally occurring radiation constantly. For example, cosmic radiation; radonAppendix G: Radiation #12;#12;P P P E E E N NN HYDROGEN ATOM DEUTERIUM ATOM TRITIUM ATOM HYDROGEN DEUTERIUM TRITIUM PROTONS NEUTRONS 1 1 1 0 1 2 ORNL-DWG 94M-5236 Appendix G: Radiation G-3 Fig. G.1

Pennycook, Steve

338

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

339

ADAPTIVE RADIATION ROSEMARY G. GILLESPIE  

E-print Network

1 A ADAPTIVE RADIATION ROSEMARY G. GILLESPIE University of California, Berkeley Adaptive radiation- tions and convergence of species groups on different land masses. Since then, adaptive radiation has diversity within a rapidly multiplying lineage." There are radiations that are not adaptive

Gillespie, Rosemary

340

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

341

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

342

Precaution and Solar Radiation Management  

Microsoft Academic Search

Solar radiation management is a form of geoengineering that involves the intentional manipulation of solar radiation with the aim of reducing global average temperature. This paper explores what precaution implies about the status of solar radiation management. It is argued that any form of solar radiation management that poses threats of catastrophe cannot constitute an appropriate precautionary measure against another

Lauren Hartzell-Nichols

2012-01-01

343

Radiation health research, 1986 - 1990  

NASA Technical Reports Server (NTRS)

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

1991-01-01

344

Radiation in particle simulations  

NASA Astrophysics Data System (ADS)

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 (plane-waves 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, Richard; Graziani, Frank; Glosli, Jim; Surh, Michael

2010-01-01

345

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

346

Radiation delivery system and method  

DOEpatents

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

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

2002-01-01

347

Status of LDEF radiation modeling  

NASA Technical Reports Server (NTRS)

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

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

1995-01-01

348

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

349

Lunar radiator shade  

NASA Technical Reports Server (NTRS)

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

Ewert, Michael K. (inventor)

1992-01-01

350

Packet personal radiation monitor  

DOEpatents

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

Phelps, J.E.

1988-03-31

351

Remote radiation dosimetry  

DOEpatents

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

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

1991-03-12

352

Remote radiation dosimetry  

DOEpatents

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

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

1991-01-01

353

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

Microsoft Academic Search

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

Vadim A. Petrov

1997-01-01

354

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

NASA Technical Reports Server (NTRS)

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

1974-01-01

355

Hard Solar Flare Radiations  

NASA Astrophysics Data System (ADS)

The space craft measurements during a solar flare demonstrate that electron precipitation with energy up to hundreds keV along the magnetic field lines to solar surface takes place. Precipitation of these particles on the solar surface is analogous with particle precipitation in aurora, but the energy in aurora is not so big. The thermal source of X-ray radiation in the corona appears above an active region. Such scenario of the flare is explained by electrodynamical solar flare model based on 3D MHD numerical simulation that demonstrate the energy accumulated in a current sheet can exceed 1e32 erg. The coronal source appears in the current sheet during fast energy release due to magnetic reconnection. The electron beams are accelerated in the field-aligned currents that generated by the Hall electric field produced in the current sheet. The development of neutron monitor data demonstrates two components of solar cosmic rays. The prompt cosmic ray component is generated during main energy release. This component consists of protons moving along the interplanetary magnetic lines. The exponential spectrum of these protons is in agreement with particle acceleration by the Lorenz electric field along the magnetic singular line in a current sheet. The similar effect has been observed in the laboratory experiments with high power discharge - pinch discharge. The similarity and difference of particle acceleration in a linear pinch effect and in the current sheet is discussed. The flares produce also a delayed component with power spectrum E^{-gamma} with gamma ~ 5. Such big gamma is difficult to explain by acceleration in a shock. Apparently, the delayed component spectrum is formed during particle diffusion in the turbulent magnetic field.

Podgorny, I.; Podgorny, A.; Vashenyuk, E.

2008-09-01

356

LDEF Satellite Radiation Analyses  

NASA Technical Reports Server (NTRS)

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

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

1996-01-01

357

Semiconductor radiation detector  

DOEpatents

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

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

2010-03-30

358

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

359

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

360

Aerothermodynamic radiation studies  

NASA Technical Reports Server (NTRS)

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

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

1991-01-01

361

Solar cell radiation handbook  

NASA Technical Reports Server (NTRS)

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

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

1982-01-01

362

Dosimetry for radiation processing  

NASA Astrophysics Data System (ADS)

During the past few years significant advances have taken place in the different areas of dosimetry for radiation processing, mainly stimulated by the increased interest in radiation for food preservation, plastic processing and sterilization of medical products. Reference services both by international organizations (IAEA) and national laboratories have helped to improve the reliability of dose measurements. Several dosimeter systems like calorimetry, perspex, and radiochromic dye films are being improved and new systems have emerged, e.g. spectrophotometry of dichromate solution for reference and sterilization dosimetry, optichromic dosimeters in the shape of small tubes for food processing, and ESR spectroscopy of alanine for reference dosimetry. In this paper the special features of radiation processing dosimetry are discussed, several commonly used dosimeters are reviewed, and factors leading to traceable and reliable dosimetry are discussed.

Miller, Arne

363

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.

364

Audible radiation monitor  

SciTech Connect

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

Odell, D.M.C.

1992-12-31

365

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)] [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

366

Nanofocusing of electromagnetic radiation  

NASA Astrophysics Data System (ADS)

Nanofocusing of electromagnetic radiation, that is, reducing the cross sections of propagating optical modes far beyond the diffraction limit in dielectric media, can be achieved in tapered metal-dielectric waveguides that support surface plasmon-polariton modes. Although the main principles of nanofocusing were formulated over a decade ago, a deep theoretical understanding and conclusive experimental verification were achieved only a few years ago. These advances have spawned a variety of new important technological possibilities for the efficient delivery, control and manipulation of optical radiation on the nanoscale. Here, we present the underlying physical principles of radiation nanofocusing in metallic nanostructures, overview recent progress and major developments, and consider future directions and potential applications of this subfield of nano-optics.

Gramotnev, Dmitri K.; Bozhevolnyi, Sergey I.

2014-01-01

367

Radiation-associated thyrotoxicosis  

SciTech Connect

We studied 154 consecutive patients with a diagnosis of thyrotoxicosis seen at Roswell Park Memorial Institute from 1963 to 1982. The retrospective review of the clinical materials revealed that 23 (15%) had a previous history of therapeutic radiation for various diseases. The radiation dose ranged from several to 3600 rads to the thyroid with a mean latency of 14.2 +/- 3.0 years. In 11 out of 16 patients who were tested for antithyroglobulin and antimicrosomal showed positive titers of either or both antibodies (69%). In a small number of patients, thyroid stimulating immunoglobulins were studied; long-acting thyroid stimulators (LATS) were positive in one of six tested and thyrotrophin binding inhibitory immunoglobulins (TBII) in five of eight. The radiation-associated thyroidal dysfunction appears to be associated with the organ-specific autoimmune processes and could manifest as either hypo- or hyperfunction of the gland.

Katayama, S.; Shimaoka, K.; Osman, G.

1986-10-01

368

ARTICLES: Corrugated focusing gratings for coupling radiation in and out of diffused LiNbO3 waveguides  

Microsoft Academic Search

A fabrication method is described and the results are given of an investigation of corrugated periodic and focusing gratings on the surfaces of diffused waveguides in LiNbO3. The paraxial approximation is used to obtain analytic expressions for the optical parameters of a system employed to form focusing gratings designed to ensure the minimum dimensions of a focusing spot. In an

Yurii V. Gulyaev; Yu M. Dikaev; Yu L. Kopylov; I. M. Kotelyanskii; V. B. Kravchenko; E. N. Mirgorodskaya; V. P. Orlov

1983-01-01

369

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

370

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

SciTech Connect

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

Shi Run [Polar Research Institute of China, Shanghai (China); Ni, Binbin [Department of Atmospheric and Oceanic Sciences, UCLA, Los Angeles, California 90095-1565 (United States); Gu Xudong [Institute of Geophysics and Planetary Physics, UCLA, Los Angeles, California 90095-1567 (United States); Zhao Zhengyu; Zhou Chen [Department of Space Physics, Wuhan University, Wuhan, Hubei (China)

2012-07-15

371

LDEF Satellite Radiation Analyses  

NASA Technical Reports Server (NTRS)

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

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

1996-01-01

372

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

373

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

374

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

375

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

376

Stochastic models of diffusion-controlled ionic reactions in radiation-induced spurs. 2. Low-permittivity solvents  

Microsoft Academic Search

The diffusion-controlled recombination of small clusters of ions in low-permittivity solvents is considered. A Monte Carlo simulation technique used previously for high-permittivity solvents is introduced and discussed briefly. The independent reaction times (IRT) simulation method is described, and its implementation for the kinetics of ion clusters is detailed. The IRT approximation is tested against the full Monte Carlo simulation for

N. J. B. Green; M. J. Pilling; S. M. Pimblott; P. Clifford

1989-01-01

377

Modeling gradual diffusion changes in radiation belt electron phase space density for the March 2013 Van Allen Probes case study  

NASA Astrophysics Data System (ADS)

March 2013 provided the first equinoctial period when all of the instruments on the Van Allen Probes spacecraft were fully operational. This interval was characterized by disturbances of outer zone electrons with two time scales of variation, diffusive and rapid dropout and restoration. A radial diffusion model was applied to the monthlong interval to confirm that electron phase space density is well described by radial diffusion for the whole month at low first invariant ? 400 MeV/G but peaks in phase space density observed by the Energetic Particle, Composition, and Thermal Plasma (ECT) instrument suite at higher first invariant are not reproduced by radial transport from a source at higher L. The model does well for much of the monthlong interval, capturing three of four enhancements in phase space density which emerge from the outer boundary, while the strong enhancement following dropout on 17-18 March requires local acceleration at higher first invariant (M=1000 MeV/G versus 200 MeV/G) not included in our model. We have incorporated phase space density from ECT measurement at the outer boundary and plasmapause determination from the Electric Field and Waves (EFW) instrument to separate hiss and chorus loss models.

Li, Zhao; Hudson, Mary; Jaynes, Allison; Boyd, Alexander; Malaspina, David; Thaller, Scott; Wygant, John; Henderson, Michael

2014-10-01

378

Unruh radiation and Interference effect  

E-print Network

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

Satoshi Iso; Yasuhiro Yamamoto; Sen Zhang

2011-02-23

379

Paradoxes of Thermal Radiation  

ERIC Educational Resources Information Center

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

Besson, U.

2009-01-01

380

SSC environmental radiation shielding  

Microsoft Academic Search

The environmental radiation shielding requirements of the SSC have been evaluated using currently available computational tools that incorporate the well known processes of energy loss and degradation of high energy particles into Monte Carlo computer codes. These tools permit determination of isodose contours in the matter surrounding a source point and therefore the specification of minimum thicknesses or extents of

1987-01-01

381

Photovoltaic radiation detector element  

DOEpatents

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

Agouridis, D.C.

1980-12-17

382

Radiation tolerant SMART electronics  

Microsoft Academic Search

Summary form only given, as follows. SMART transmitters contain a microprocessor and other digital electronic circuits that are used to enhance accuracy, provide communications, reduce maintenance, and otherwise facilitate use. SMART transmitters are used extensively in factories, refineries, and elsewhere, but they are not used in nuclear power plants, in part because they have low tolerance to ionizing radiation. A

D. H. Loescher; J. M. Weiss

1991-01-01

383

CCTV for radiation environments  

SciTech Connect

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

Shaufl, R.A.

1985-01-01

384

Manifolds and Radiation Protection  

NASA Astrophysics Data System (ADS)

During the past 40 years humans have travelled beyond Earth's atmosphere, orbiting the planets for extended periods of time and landing on the Moon. Humans have survived this overwhelming challenge but to assure future exploration of space further expertise in the long term survival in space must be obtained. The International Space Station (ISS) provides this opportunity and allows space scientist to fine-tune their knowledge and prepare for even bolder human space missions. In this work we focus on the aspect of radiation, perhaps the most complex one from a physical and physiological perspective. Travel beyond the Earth's atmosphere and especially to Moon and Mars requires a precise consideration of the radiation environment as radiation exposure could be a show-stopper. At the moment scientists have not yet developed complete and reliable systems for radiation protection. Most likely an adequate level of protection will be reached through an integrated countermeasure system which could include: shields, monitoring of the environment, drugs to protect from damage, etc.

Rossitto, Franco; Petrov, Vladislav M.; Ongaro, Filippo

385

Atmospheric Processes--Radiation  

NSDL National Science Digital Library

This activity begins with an explanation of the heat transfer processes in general and then focuses on radiation. In the activity, students investigate how different surfaces absorb heat and apply their experience with the surfaces to interpret real-world situations.

2010-01-01

386

Air radiator cooling tower  

Microsoft Academic Search

The invention discloses an air radiator cooling tower comprising a piping system for the supply and removal of water circulating in cooled tubular elements joined into groups by means of tubular girders, an exhaust tower for the circulation of cooling air, and a device for the excitation of oscillations transmitted through direct contact over the surface of the tubular elements

B. B. Kazanovich; G. R. Santurian; P. A. Fischenko

1979-01-01

387

RADIATION SHIELDING MATERIALS  

Microsoft Academic Search

A shielding material is described which has a high shielding ; effectiveness per unit volume and a high capacity for absorbing radiations. The ; material comprises a chemical complex of trivalent cobalt or chromium, such as ; the perrhenates and hexamino trihalides, in combination with a structural ; material such as iron, stainless steel, etc. The complex may be melted

Borst

1962-01-01

388

Radiation Curable Conductive Ink  

Microsoft Academic Search

A radiation curable, screen printable conductive ink has been developed for use on thermoplastic circuit boards. The fast application and cure of this solventless material allow mass production of low cost circuits suitable for use with systems that can tolerate higher resistance. In one application, a photoflash array, Flipflash, utilizes a piezoelectric crystal to provide the high voltage necessary to

D. A. Bolon; G. M. Lucas; S. H. Schroeter

1978-01-01

389

Materials for Radiation Detection.  

National Technical Information Service (NTIS)

The report surveys the available information (complete through 1971) on detectors for the electromagnetic radiation spectrum in the wavelength range 10 to the minus 10th power to 1 cm. The detectors are divided according to wavelength range into four grou...

1974-01-01

390

Psoriasis and ultraviolet radiation  

SciTech Connect

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

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

1993-09-01

391

Radiation belts of Jupiter  

Microsoft Academic Search

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

R. W. Fillius; C. E. McIlwain

1974-01-01

392

Surface Radiation Budget  

NASA Technical Reports Server (NTRS)

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

Stackhouse, Paul W. (Principal Investigator)

393

Radiation detector spectrum simulator  

DOEpatents

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

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

1985-04-09

394

Radiation Protection Basics  

MedlinePLUS

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

395

Local microwave background radiation  

E-print Network

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

Domingos S. L. Soares

2006-07-11

396

Foundations of radiation hydrodynamics  

Microsoft Academic Search

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

D. Mihalas; B. W. Mihalas

1984-01-01

397

Radiation injury of bone  

SciTech Connect

This monograph is devoted to the characteristics of radiation injuries arising in hitherto unaffected parts of the skeleton during the treatment of neoplasms by radiotherapy. These changes frequently accompany the beneficial effects of radiotherapy, and can easily be misunderstood in the absence of any clear idea of their character. An understanding of the mechanism and conditions of appearance of radiation injuries of the skeleton and a knowledge of their clinical and radiological features are essential for physicians and surgeons caring for patients who have been treated by using radiotherapy and for experimental scientists whose work involves such methods. The effect of irradiation is determined by the topographical relations within the irradiated object, the character of distribution of the dose, and the size of the dose. The radiation injuries of the skeleton described in the book were observed during the treatment of carcinoma of the breast, lung, esophagus, and uterus, of malignant tumors in the mouth, certain pituitary tumors, and hemangiomas of the skin in children, by means of ionizing radiation obtained from various sources. A few observations relate to patients treated for certain other diseases. The text is illustrated by roentgenograms on the basis of which the diagnoses were made and the course of the lesion was subsequently confirmed, and also by operative and histological specimens. The book also contains many schemes drawn from roentgenograms.

Shimanovskaya, K.; Shiman, A.D.

1983-01-01

398

ATMOSPHERIC RADIATION MEASUREMENT PROGRAM  

EPA Science Inventory

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

399

and Black Hole Radiation  

Microsoft Academic Search

We compute the eect of quantum mechanical backreaction on the spectrum of radiation in a dynamical moving mirror model, mimicing the eect of a gravitational collapse geometry. Our method is based on the use of a combined WKB and saddle-point approximation to implement energy conservation in the calculation of the Bogolyubov coecients, in which we assume that the mirror particle

Niels Tuning; Herman Verlinde

400

Radiation Safety and Physics  

Microsoft Academic Search

Radiation is a term that encompasses a broad category of energy-containing emissions that have no mass and travel at the speed of light. The electromagnetic (EM) spectrum is made up of subcategories of these forms of energy, the properties and effects of which are dependent upon the wavelength and frequency of the emitted energy. Unlike sound waves (and ultrasound), electromagnetic

Howard C. Snider; FACS Montgomery

401

VDT Emissions Radiate Debate.  

ERIC Educational Resources Information Center

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

Morgan, Bill

1990-01-01

402

Future Synchrotron Radiation Sources  

Microsoft Academic Search

Sources of synchrotron radiation (also called synchrotron light) and their associated research facilities have experienced a spectacular growth in number, performance, and breadth of application in the past two to three decades. In 1978 there were eleven electron storage rings used as light sources. Three of these were small rings, all below 500 mega-electron volts (MeV), dedicated to this purpose;

Winick

2003-01-01

403

Rhabdomyosarcoma: Radiation Therapy  

MedlinePLUS

... they are available. Three-dimensional conformal radiation therapy (3D-CRT): 3D-CRT uses special computers to precisely map the ... therapy (IMRT): IMRT is an advanced form of 3D therapy. Along with shaping the beams and aiming ...

404

Hawking Radiation As Tunneling  

Microsoft Academic Search

We present a short and direct derivation of Hawking radiation as a tunneling process, based on particles in a dynamical geometry. The imaginary part of the action for the classically forbidden process is related to the Boltzmann factor for emission at the Hawking temperature. Because the derivation respects conservation laws, the exact spectrum is not precisely thermal. We compare and

Maulik K. Parikh; Frank Wilczek

2000-01-01

405

Radiation Therapy (For Parents)  

MedlinePLUS

... may have some restrictions. The radiation in the implant may send high-energy rays outside the patient's body, so visitors must be protected from exposure. The child will be in a private room, and nurses and visitors can enter only for short periods of time. The child will have all ...

406

Nuclear Radiation Damages Minds!  

ERIC Educational Resources Information Center

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

Blai, Boris, Jr.

407

Cambridge Cosmology: Relic Radiation  

NSDL National Science Digital Library

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

Shellard, Paul

408

Radiation Dose Estimates from  

E-print Network

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

409

Radiation proteomics: a brief overview.  

PubMed

Acute biological effects caused by the exposure to high doses of radiation, either ionizing or nonionizing, are relatively well-known but the delayed effects, occurring decades after exposure, are difficult to predict. The knowledge of the acute and delayed effects of the low doses of ionizing radiation (e.g. bystander effect) or nonionizing radiation (e.g. radiation emitted by wireless communication devices) is not yet reliably established. Often the acute effects of low doses are small and difficult to discover and replicate in scientific studies. Chronic effects of prolonged exposures to low-dose radiation for decades are virtually unknown and often not possible to predict on the basis of the knowledge gained from acute exposures to high doses of radiation. Physiological significance of the biological effects induced by low doses of radiation is not known. The same lack of predictability of outcomes applies to the delayed effects of high-dose radiation exposures. Proteomics, supplemented with other "omics" techniques, might be the best way forward to find out the target molecules of radiation, the biomarkers of radiation exposure and the physiological and health significance of the acute and delayed biological effects caused by the exposures to high- and low-dose radiation. However, the currently available database of radiation effects on proteomes is far too small to be useful in formulation of new hypotheses concerning health consequences of radiation exposures. PMID:24376023

Leszczynski, Dariusz

2014-03-01

410

Computer Based Radiation Safety Training for Hospital Radiation  

Microsoft Academic Search

Conducting a hospital -based radiation safety training class may lead to temporary technologist staffing shortages resulting in a reduction of patient services or even the cessation of all routine patient services. Use of an interactive computer-based radiation safety' training software program may provide a prac tical alternative for hospital diagnostic and therapeutic radiation departments, as well as other hospital departments

Daniel S. Hamilton; Matthew M. Peck; Hao Yu; Kimberlee J. Kearfott

411

ACS WFC CCD Radiation Test: The Radiation Environment  

E-print Network

1 ACS WFC CCD Radiation Test: The Radiation Environment Michael R. Jones Space Telescope Science of external surfaces by naturally occurring atomic oxygen. CCD detectors are particularly vulnerable to damage) Charge-Coupled Device (CCD) detector. 1. Introduction Radiation damage effects in CCD imagers have been

Sirianni, Marco

412

The regression of net radiation upon solar radiation  

Microsoft Academic Search

A number of studies have sought to relate net radiation over natural surfaces to incoming global radiation. Several deficiencies are noted in interpretation of the simple regression models used for this purpose in the past. A modification proposed for correction of these deficiencies introduces a new longwave exchange coefficient, ?, that relates the change in net longwave radiation to the

Lloyd W. Gay

1971-01-01

413

Radiation Safety Training Basic Radiation Safety Training for  

E-print Network

Radiation Safety Training Basic Radiation Safety Training for Sealed Source Users for Physics 461 Protocol Title: Training for Sealed Source Users Drafted By: Chris Millsaps, RSS Reviewers: ZB, TU, GS Purpose: To provide basic radiation safety training to the users of sealed sources located

Dai, Pengcheng

414

Drug Information Related to Radiation Emergencies  

MedlinePLUS

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

415

An interpretation of fluctuations in enzyme catalysis rate, spectral diffusion, and radiative component of lifetimes in terms of electric field fluctuations  

PubMed Central

Time-dependent fluctuations in the catalysis rate (?k(t)) observed in single-enzyme experiments were found in a particular study to have an autocorrelation function decaying on the same time scale as that of spectral diffusion ??0(t). To interpret this similarity, the present analysis focuses on a factor in enzyme catalysis, the local electrostatic interaction energy (E) at the active site and its effect on the activation free energy barrier. We consider the slow fluctuations of the electrostatic interaction energy (?E(t)) as a contributor to ?k(t) and relate the latter to ??0(t). The resulting relation between ?k(t) and ??0(t) is a dynamic analog of the solvatochromism used in interpreting solvent effects on organic reaction rates. The effect of the postulated ?E(t) on fluctuations in the radiative component (??r?1(t)) of the fluorescence decay of chromophores in proteins also is examined, and a relation between ??r?1(t) and ??0(t) is obtained. Experimental tests will determine whether the correlation functions for ?k(t), ??0(t), and ??r?1 are indeed similar for any enzyme. Measurements of dielectric dispersion, ?(?), for the enzyme discussed elsewhere will provide further insight into the correlation function for ?E(t). They also will determine whether fluctuations in the nonradiative component ?nr?1 of the lifetime decay has a different origin, fluctuations in distance for example. PMID:17911244

Prakash, Meher K.; Marcus, R. A.

2007-01-01

416

Radiation Therapy for Testicular Cancer  

MedlinePLUS

... testicular cancer Next Topic Chemotherapy for testicular cancer Radiation therapy for testicular cancer This treatment uses high- ... cells or slow their growth. In testicular cancer, radiation is mainly used to kill cancer cells that ...

417

Conical electromagnetic radiation flux concentrator  

NASA Technical Reports Server (NTRS)

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

Miller, E. R.

1972-01-01

418

Acceleration and Classical Electromagnetic Radiation  

E-print Network

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

E. N. Glass

2008-01-09

419

Hemoglobin, radiation, morbidity and survival  

SciTech Connect

Analyses concerned with a group of patients treated by radiotherapy for carcinoma of the bronchus give evidence to support the view that oxygen tension at the time of radiation therapy is important both in determining tumor control and radiation morbidity.

Dische, S.; Saunders, M.I.; Warburton, M.F.

1986-08-01

420

RADIATION ENVIRONMENT OF GROWTH CHAMBERS  

EPA Science Inventory

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

421

Radiation from Cardiac Imaging Tests  

MedlinePLUS

... Key Words: cardiac imaging techniques computed tomography imaging nuclear medicine radiation Next Section Introduction Many patients are referred by ... by heart disease, appropriate use criteria classify a nuclear stress test as ... radiation exposure. The appropriate use criteria cover dozens of ...

422

Nuclear Radiation and the Thyroid  

MedlinePLUS

... American Thyroid Association website at www.thyroid.org . Nuclear Radiation and the Thyroid Color Brochure for Saving and Printing (PDF File, 732KB) Nuclear Radiation and the Thyroid Black and White Brochure for ...

423

Gamma radiation field intensity meter  

DOEpatents

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

Thacker, L.H.

1994-08-16

424

Gamma radiation field intensity meter  

DOEpatents

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

Thacker, L.H.

1995-10-17

425

Stromal Mediation of Radiation Carcinogenesis  

PubMed Central

Ionizing radiation is a well-established carcinogen in human breast and rodent mammary gland. This review addresses evidence that radiation elicits the critical stromal context for cancer, affecting not only frequency but the type of cancer. Recent data from the breast tumors of women treated with radiation therapy and the cellular mechanisms evident in experimental models suggest that radiation effects on stromal-epithelial interactions and tissue composition are a major determinant of cancer development. PMID:21181431

2011-01-01

426

Stromal Mediation of Radiation Carcinogenesis  

Microsoft Academic Search

Ionizing radiation is a well-established carcinogen in human breast and rodent mammary gland. This review addresses evidence\\u000a that radiation elicits the critical stromal context for cancer, affecting not only frequency but the type of cancer. Recent\\u000a data from the breast tumors of women treated with radiation therapy and the cellular mechanisms evident in experimental models\\u000a suggest that radiation effects on

Mary Helen Barcellos-Hoff

2010-01-01

427

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

E-print Network

Multiscale Modeling of Radiation ResponseMultiscale Modeling of Radiation ResponseMultiscale Modeling of Radiation ResponseMultiscale Modeling of Radiation Response Effects of Radiation Quality and HypoxiaEffects of Radiation Quality and Hypoxia Robert D. Stewart, Ph.D.Robert D. Stewart, Ph

Stewart, Robert D.

428

Study of coupled double diffusive convection-radiation in a tilted cavity via a hybrid multi-relaxation time-lattice Boltzmann-finite difference and discrete ordinate methods  

NASA Astrophysics Data System (ADS)

The coupled double diffusive natural convection and radiation in a tilted and differentially heated square cavity containing a non-gray air-CO2 (or air-H2O) mixtures was numerically investigated. The horizontal walls are insulated and impermeable and the vertical walls are maintained at different temperatures and concentrations. The hybrid lattice Boltzmann method with the multiple-relaxation time model is used to compute the hydrodynamics and the finite difference method to determine temperatures and concentrations. The discrete ordinates method combined to the spectral line-based weighted sum of gray gases model is used to compute the radiative term and its spectral aspect. The effects of the inclination angle on the flow, thermal and concentration fields are analyzed for both aiding and opposing cases. It was found that radiation gas modifies the structure of the velocity and thermal fields by generating inclined stratifications and promoting the instabilities in opposing flows.

Moufekkir, Fayçal; Moussaoui, Mohammed Amine; Mezrhab, Ahmed; Naji, Hassan

2014-09-01

429

Carcinoma of the anal canal: radiation or radiation plus chemotherapy  

SciTech Connect

An editorial is presented which discusses the treatment of carcinoma of the anal canal. Following the initial report of the successful preoperative use of combined chemotherapy and radiation by Nigro in 1974, several centers have confirmed the effectiveness of such combinations either as preoperative or as definitive treatment of anal carcinomas, and many patients are now being referred for radiation therapy. The article by Cantril in this issue describe the successful treatment of anal carcinomas by radiation alone, and raises the important issue of whether radiation plus chemotherapy is more effective treatment than radiation alone for squamous or cloacogenic carcinomas arising in the anal canal or perianal area. Several studies are cited.

Cummings, B.J.

1983-09-01

430

Working With Radiation For Research  

E-print Network

Radiation Source mrem/year Cosmic rays 30 Terrestrial Radioactivity 30 Ingested Radioactivity 40 Inhaled house, one year 30 To flight crew from cosmic rays per year 150 #12;13 Wear your radiation badge when1 Working With Radiation For Research Thomas Cummings Junior Physicist Environmental Health

Jia, Songtao

431

Radiation Propulsion For Maintaining Orbits  

NASA Technical Reports Server (NTRS)

Brief report proposes radiative propulsion systems for maintaining precise orbits of spacecraft. Radiation from electrical heaters directed outward by paraboloidal reflectors to produce small forces to oppose uncontrolled drag and solar-radiative forces perturbing orbits. Minimizes or eliminates need to fire rocket thrusters to correct orbits.

Richter, Robert

1995-01-01

432

RADIATION AND CLOUD MONITORING STATIONS  

E-print Network

, engineers, and technicians in the installation of an Atmospheric Radiation and Cloud Station, or ARCS to cooling, but they also can absorb infrared radiation leaving Earth's surface and contribute to warmingRADIATION AND CLOUD MONITORING STATIONS HELP SCIENTISTS IMPROVE GLOBAL CLIMATE MODELS "I'VE LOOKED

Reeves, Geoffrey D.

433

Radiation Safety (Revised March 2010)  

E-print Network

Properties of radioactivity and units of measure 9 Electronic sources of ionizing radiation 10 Interactions of particulate radiation with matter 12 Interactions of photons with matter 13 Measurement to Workers; Inspections 27 10 CFR Part 20Standards for Protection Against Radiation 28 10 CFR Part 35

Kay, Mark A.

434

Radiation Therapy Technology Professional Curriculum  

E-print Network

Radiation Therapy Technology Professional Curriculum Fall Semester RT 3000 Concepts of Clinical Care RT 3010 Introductory Radiation Physics RT 3310 Clinical Practicum I RT 3110 Clinical Aspects of Radiation Therapy Semester Total Credits 12 Winter Semester RT 5650 Pathophysiology for Health Sciences RT

Berdichevsky, Victor

435

Radiation Protection Guidance Hospital Staff  

E-print Network

Page 1 Radiation Protection Guidance For Hospital Staff Prepared for Stanford The privilege to use ionizing radiation at Stanford University, Stanford Hospital and Clinics, Lucile Packard with radioactive materials or radiation devices are responsible for knowing and adhering to applicable requirements

Kay, Mark A.

436

Radiation and Health Thormod Henriksen  

E-print Network

Radiation and Health by Thormod Henriksen and Biophysics group at UiO #12;Preface The present book. The address is: http://www.mn.uio.no/fysikk/tjenester/kunnskap/straling/ III. Radiation and Health Written of ionizing radiation. Efforts were made to describe the background ra- diation as well as the release

Johansen, Tom Henning

437

Spectroscopy Interaction of electromagnetic radiation  

E-print Network

Spectroscopy 691 Interaction of electromagnetic radiation with atoms or molecules #12;Bacteriorhodopsin: a light-driven proton pump 486 #12;Electromagnetic Radiation 692 harmonic wave (Maxwell): y;Spectroscopy 691 Interaction of electromagnetic radiation with atoms or molecules two processes: emission

Gerwert, Klaus

438

Lunar radiation environment  

NASA Astrophysics Data System (ADS)

One of the goals of the CRaTER investigation is to characterize the radiation environment near the Moon in order to enable exploration. The state-of-the-art understanding developed thus far during the LRO mission is documented in a special issue of the Spaceweather Journal entitled “Space Weather: Building the observational foundation to deduce biological effects of space radiation” (Schwadron et al., 2013a). This recently published CRaTER work probes deeper into the physics of the radiation environment at the Moon. It motivates and provides the scientific basis for new investigations in the next phase of the LRO mission. The effects of Galactic Cosmic Rays (GCRs) and Solar Energetic Particles (SEPs) range from chemical modification of the regolith, the generation of a radiation albedo that is increasingly illuminating chemical properties of the regolith, causing charging of the regolith and hazards to human explorers and robotic missions. Low-lunar orbit provides a platform for measuring SEP anisotropy over timescales of 2 hours both parallel and perpendicular to the ecliptic plane, and so far we have observed more than 18 SEP events with time-variable anisotropies during the LRO mission. Albedo proton maps of the Moon from CRaTER indicate that the flux of lunar albedo protons is correlated with elemental abundances at the lunar surface. The yield of albedo protons from the maria is 1% higher than the yield from the highlands, and there are localized peaks with even higher contrast (that may be co-located with peaks in trace elemental abundances as measured by the Lunar Prospector Gamma Ray Spectrometer). The Moon’s radiation environment both charges and affects the chemistry in the Moon’s polar regions, particularly in PSRs. This makes these regions a prime target for new CRaTER observations, since CRaTER measures GCRs and SEPs that penetrate the regolith down to 10s of cm. Thus, we review emerging discoveries from LRO/CRaTER’s remarkable exploration of moon’s radiation environment, its implications for human exploration, and its interaction with lunar regolith.

Schwadron, Nathan; Spence, Harlan; Wilson, Jody

439

Pregnancy and Radiation Protection  

SciTech Connect

Several modalities are currently utilized for diagnosis and therapy, by appropriate application of x-rays. In diagnostic radiology, interventional radiology, radiotherapy, interventional cardiology, nuclear medicine and other specialties radiation protection of a pregnant woman as a patient, as well as a member of the operating personnel, is of outmost importance. Based on radiation risk, the termination of pregnancy is not justified if foetal doses are below 100 mGy. For foetal doses between 100 and 500 mGy, a decision is reached on a case by case basis. In Diagnostic Radiology, when a pregnant patient takes an abdomen CT, then an estimation of the foetus' dose is necessary. However, it is extremely rare for the dose to be high enough to justify an abortion. Radiographs of the chest and extremities can be done at any period of pregnancy, provided that the equipment is functioning properly. Usually, the radiation risk is lower than the risk of not undergoing a radiological examination. Radiation exposure in uterus from diagnostic radiological examinations is unlikely to result in any deleterious effect on the child, but the possibility of a radiation-induced effect can not be entirely ruled out. The effects of exposure to radiation on the foetus depend on the time of exposure, the date of conception and the absorbed dose. Finally, a pregnant worker can continue working in an x-ray department, as long as there is reasonable assurance that the foetal dose can be kept below 1 mGy during the pregnancy. Nuclear Medicine diagnostic examinations using short-lived radionuclides can be used for pregnant patient. Irradiation of the foetus results from placental transfer and distribution of radiopharmaceuticals in the foetal tissues, as well as from external irradiation from radioactivity in the mother's organ and tissues. As a rule, a pregnant patient should not undergo therapy with radionuclide, unless it is crucial for her life. In Radiotherapy, the patient, treating oncologist, other team and family members should carefully discuss for the decision of abortion. Important factors must be considered such as the stage and aggressiveness of the tumour, the location of the tumour, the stage of pregnancy, various therapies etc.

Gerogiannis, J. [Nicosia General Hospital, Nicosia (Cyprus); Stefanoyiannis, A. P. [University General Hospital of Athens 'Attikon', Athens (Greece)

2010-01-21

440

Space Radiation Cancer Risks  

NASA Technical Reports Server (NTRS)

Space radiation presents major challenges to astronauts on the International Space Station and for future missions to the Earth s moon or Mars. Methods used to project risks on Earth need to be modified because of the large uncertainties in projecting cancer risks from space radiation, and thus impact safety factors. We describe NASA s unique approach to radiation safety that applies uncertainty based criteria within the occupational health program for astronauts: The two terrestrial criteria of a point estimate of maximum acceptable level of risk and application of the principle of As Low As Reasonably Achievable (ALARA) are supplemented by a third requirement that protects against risk projection uncertainties using the upper 95% confidence level (CL) in the radiation cancer projection model. NASA s acceptable level of risk for ISS and their new lunar program have been set at the point-estimate of a 3-percent risk of exposure induced death (REID). Tissue-averaged organ dose-equivalents are combined with age at exposure and gender-dependent risk coefficients to project the cumulative occupational radiation risks incurred by astronauts. The 95% CL criteria in practice is a stronger criterion than ALARA, but not an absolute cut-off as is applied to a point projection of a 3% REID. We describe the most recent astronaut dose limits, and present a historical review of astronaut organ doses estimates from the Mercury through the current ISS program, and future projections for lunar and Mars missions. NASA s 95% CL criteria is linked to a vibrant ground based radiobiology program investigating the radiobiology of high-energy protons and heavy ions. The near-term goal of research is new knowledge leading to the reduction of uncertainties in projection models. Risk projections involve a product of many biological and physical factors, each of which has a differential range of uncertainty due to lack of data and knowledge. The current model for projecting space radiation cancer risk relies on the three assumptions of linearity, additivity, and scaling along with the use of population averages. We describe uncertainty estimates for this model, and new experimental data that sheds light on the accuracy of the underlying assumptions. These methods make it possible to express risk management objectives in terms of quantitative metrics, i.e., the number of days in space without exceeding a given risk level within well defined confidence limits. The resulting methodology is applied to several human space exploration mission scenarios including lunar station, deep space outpost, and a Mars mission. Factors that dominate risk projection uncertainties and application of this approach to assess candidate mitigation approaches are described.

Cucinotta, Francis A.

2007-01-01

441

Radiation Effects: Core Project  

NASA Technical Reports Server (NTRS)

The risks to personnel in space from the naturally occurring radiations are generally considered to be one of the most serious limitations to human space missions, as noted in two recent reports of the National Research Council/National Academy of Sciences. The Core Project of the Radiation Effects Team for the National Space Biomedical Research Institute is the consequences of radiations in space in order to develop countermeasure, both physical and pharmaceutical, to reduce the risks of cancer and other diseases associated with such exposures. During interplanetary missions, personnel in space will be exposed to galactic cosmic rays, including high-energy protons and energetic ions with atomic masses of iron or higher. In addition, solar events will produce radiation fields of high intensity for short but irregular durations. The level of intensity of these radiations is considerably higher than that on Earth's surface, and the biological risks to astronauts is consequently increased, including increased risks of carcinogenesis and other diseases. This group is examining the risk of cancers resulting from low-dose, low-dose rate exposures of model systems to photons, protons, and iron by using ground-based accelerators which are capable of producing beams of protons, iron, and other heavy ions at energies comparable to those encountered in space. They have begun the first series of experiments using a 1-GeV iron beam at the Brookhaven National Laboratory and 250-MeV protons at Loma Linda University Medical Center's proton synchrotron facility. As part of these studies, this group will be investigating the potential for the pharmaceutical, Tamoxifen, to reduce the risk of breast cancer in astronauts exposed to the level of doses and particle types expected in space. Theoretical studies are being carried out in a collaboration between scientists at NASA's Johnson Space Center and Johns Hopkins University in parallel with the experimental program have provided methods and predictions which are being used to assess the levels of risks to be encountered and to evaluate appropriate strategies for countermeasures. Although the work in this project is primarily directed toward problems associated with space travel, the problem of protracted exposures to low-levels of radiation is one of national interest in our energy and defense programs, and the results may suggest new paradigms for addressing such risks.

Dicello, John F.

1999-01-01

442

Acute Cerebrovascular Radiation Syndrome: Radiation Neurotoxicity , mechanisms of CNS radiation injury, advanced countermeasures for Radiation Protection of Central Nervous System.  

NASA Astrophysics Data System (ADS)

Key words: Cerebrovascular Acute Radiation Syndrome (Cv ARS), Radiation Neurotoxins (RNT), Neurotransmitters, Radiation Countermeasures, Antiradiation Vaccine (ArV), Antiradiation Blocking Antibodies, Antiradiation Antidote. Psychoneuroimmunology, Neurotoxicity. ABSTRACT: To review the role of Radiation Neurotoxins in triggering, developing of radiation induced central nervous system injury. Radiation Neurotoxins - rapidly acting blood toxic lethal agent, which activated after irradiation and concentrated, circulated in interstitial fluid, lymph, blood with interactions with cell membranes, receptors and cell compartments. Radiation Neurotoxins - biological molecules with high enzymatic activity and/or specific lipids and activated or modified after irradiation. The Radiation Neurotoxins induce increased permeability of blood vessels, disruption of the blood-brain barrier, blood-cerebrospinal fluid (CSF) barrier and developing severe disorder of blood macro- and micro-circulation. Principles of Radiation Psychoneuro-immunology and Psychoneuro-allergology were applied for determination of pathological processes developed after irradiation or selective administration of Radiation Neurotoxins to radiation naïve mammals. Effects of radiation and exposure to radiation can develop severe irreversible abnormalities of Central Nervous System, brain structures and functions. Antiradiation Vaccine - most effective, advanced methods of protection, prevention, mitigation and treatment and was used for of Acute Radiation Syndromes and elaboration of new technology for immune-prophylaxis and immune-protection against ?, Heavy Ion, Neutron irradiation. Results of experiments suggested that blocking, antitoxic, antiradiation antibodies can significantly reduce toxicity of Radiation Toxins. New advanced technology include active immune-prophylaxis with Antiradiation Vaccine and Antiradiation therapy that included specific blocking antibodies to Radiation Neurotoxins. Antiradiation Vaccine and Antiradiation IgG preparations - prospective effective antidote/countermeasure for ?-irradiation, heavy ions irradiation, neutron irradiation. Recommendations for treatment and immune-prophylaxis of CNS injury, induced by radiation, were proposed. Specific immune therapy and specific immune prophylaxis reduce symptoms of ACvRS. This manuscript summarizes the results of experiments and considering possibility for blocking toxicological mechanisms of action of Radiation and Radiation Neurotoxins and prevention or diminishing clinical signs of injury of CNS. Experimental data suggest that Antiradiation vaccine and Antiradiation IgG with specific antibodies to Radiation Neurotoxins, Cytotoxins protect CNS against high doses of radiation.

Popov, Dmitri; Jones, Jeffrey; Maliev, Slava

443

Radiation dosimetry and biophysical models of space radiation effects  

NASA Technical Reports Server (NTRS)

Estimating the biological risks from space radiation remains a difficult problem because of the many radiation types including protons, heavy ions, and secondary neutrons, and the absence of epidemiology data for these radiation types. Developing useful biophysical parameters or models that relate energy deposition by space particles to the probabilities of biological outcomes is a complex problem. Physical measurements of space radiation include the absorbed dose, dose equivalent, and linear energy transfer (LET) spectra. In contrast to conventional dosimetric methods, models of radiation track structure provide descriptions of energy deposition events in biomolecules, cells, or tissues, which can be used to develop biophysical models of radiation risks. In this paper, we address the biophysical description of heavy particle tracks in the context of the interpretation of both space radiation dosimetry and radiobiology data, which may provide insights into new approaches to these problems.

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

2003-01-01

444

Radiation Environment Inside Spacecraft  

NASA Technical Reports Server (NTRS)

Dr. Patrick O'Neill, NASA Johnson Space Center, will present a detailed description of the radiation environment inside spacecraft. The free space (outside) solar and galactic cosmic ray and trapped Van Allen belt proton spectra are significantly modified as these ions propagate through various thicknesses of spacecraft structure and shielding material. In addition to energy loss, secondary ions are created as the ions interact with the structure materials. Nuclear interaction codes (FLUKA, GEANT4, HZTRAN, MCNPX, CEM03, and PHITS) transport free space spectra through different thicknesses of various materials. These "inside" energy spectra are then converted to Linear Energy Transfer (LET) spectra and dose rate - that's what's needed by electronics systems designers. Model predictions are compared to radiation measurements made by instruments such as the Intra-Vehicular Charged Particle Directional Spectrometer (IV-CPDS) used inside the Space Station, Orion, and Space Shuttle.

O'Neill, Patrick

2015-01-01

445

Innovations in radiation oncology  

SciTech Connect

The book contains reports of areas of growth in radiation oncology written for the practising radiation oncologist. Early chapters review conservative treatments that preserve the function and maintain or improve tumor control rates in breast, rectum, anus, head and neck, soft tissues and bones, and the eye. This is followed by a section dealing with extended field therapy encompassing total body irradiation, half body irradiation and systemic therapy with radionuclide-labelled antibodies. The potential roles of three new diagnostic imaging technologies (CT, MRI and PET) in radiotherapy are considered. Various modifications of treatment are reviewed, including hyperfractionation, accelerated treatment, accelerated hyperfractionation and neutron therapy. Also discussed is the clinical use of adjuvants to radiotherapy, such as radiosensitizers, cytotoxic drugs, interstitial and external hyperthermia and bone fixation in metastatic disease.

Withers, H.R.; Peters, L.J.

1988-01-01

446

Aharonov-Bohm Radiation  

E-print Network

A solenoid oscillating in vacuum will pair produce charged particles due to the Aharonov-Bohm (AB) interaction. We calculate the radiation pattern and power emitted for charged scalar particles. We extend the solenoid analysis to cosmic strings, and find enhanced radiation from cusps and kinks on loops. We argue by analogy with the electromagnetic AB interaction that cosmic strings should emit photons due to the gravitational AB interaction of fields in the conical spacetime of a cosmic string. We calculate the emission from a kink and find that it is of similar order as emission from a cusp, but kinks are vastly more numerous than cusps and may provide a more interesting observational signature.

Katherine Jones-Smith; Harsh Mathur; Tanmay Vachaspati

2009-11-03

447

TOPEX orbital radiation study  

NASA Technical Reports Server (NTRS)

The space radiation environment of the TOPEX spacecraft is investigated. A single trajectory was considered. The external (surface incident) charged particle radiation, predicted for the satellite, is determined by orbital flux integration for the specified trajectory. The latest standard models of the environment are used in the calculations. The evaluation is performed for solar maximum conditions. The spacecraft exposure to cosmic rays of galactic origin is evaluated over its flight path through the magnetosphere in terms of geomagnetic shielding effects, both for surface incident heavy ions and for particles emerging behind different material thickness. Limited shielding and dose evaluations are performed for simple infinite slab and spherical geometries. Results, given in graphical and tabular form, are analyzed, explained, and discussed. Conclusions are presented and commented on.

Stassinopoulos, E. G.; Barth, J. M.

1984-01-01

448

Radiation Induced Genomic Instability  

SciTech Connect

Radiation induced genomic instability can be observed in the progeny of irradiated cells multiple generations after irradiation of parental cells. The phenotype is well established both in vivo (Morgan 2003) and in vitro (Morgan 2003), and may be critical in radiation carcinogenesis (Little 2000, Huang et al. 2003). Instability can be induced by both the deposition of energy in irradiated cells as well as by signals transmitted by irradiated (targeted) cells to non-irradiated (non-targeted) cells (Kadhim et al. 1992, Lorimore et al. 1998). Thus both targeted and non-targeted cells can pass on the legacy of radiation to their progeny. However the radiation induced events and cellular processes that respond to both targeted and non-targeted radiation effects that lead to the unstable phenotype remain elusive. The cell system we have used to study radiation induced genomic instability utilizes human hamster GM10115 cells. These cells have a single copy of human chromosome 4 in a background of hamster chromosomes. Instability is evaluated in the clonal progeny of irradiated cells and a clone is considered unstable if it contains three or more metaphase sub-populations involving unique rearrangements of the human chromosome (Marder and Morgan 1993). Many of these unstable clones have been maintained in culture for many years and have been extensively characterized. As initially described by Clutton et al., (Clutton et al. 1996) many of our unstable clones exhibit persistently elevated levels of reactive oxygen species (Limoli et al. 2003), which appear to be due dysfunctional mitochondria (Kim et al. 2006, Kim et al. 2006). Interestingly, but perhaps not surprisingly, our unstable clones do not demonstrate a “mutator phenotype” (Limoli et al. 1997), but they do continue to rearrange their genomes for many years. The limiting factor with this system is the target – the human chromosome. While some clones demonstrate amplification of this chromosome and thus lend themselves to prolonged study, many tend to eliminate or rearrange the target chromosome until it is too small for further rearrangement. The observed frequency of induced instability by low and high linear-energy-transfer radiations greatly exceeds that observed for nuclear gene mutations at similar doses; hence, mutation of a gene or gene family is unlikely to be the initiating mechanism. Once initiated however, there is evidence in the GM10115 model system that it can be perpetuated over time by dicentric chromosome formation followed by bridge breakage fusion cycles (Marder and Morgan 1993), as well as recombinational events involving interstitial telomere like repeat sequences (Day et al. 1998). There is also increasing evidence that inflammatory type reactions (Lorimore et al. 2001, Lorimore and Wright 2003), presumably involving reactive oxygen and nitrogen species as well as cytokines and chemokines might be involved in driving the ustable phenotype (Liaikis et al. 2007, Hei et al. 2008). To this end there is very convincing evidence for such reactions being involved in another non-targeted effect associated with ionizing radiation, the bystander effect (Hei et al. 2008). Clearly the link between induced instability and bystander effects suggests common processes and inflammatory type reactions will likely be the subject of future investigation.

Morgan, William F.

2011-03-01

449

On source radiation  

NASA Technical Reports Server (NTRS)

The power output from given sources is usually ascertained via an energy flux integral over the normal directions to a remote (far field) surface; an alternative procedure, which utilizes an integral that specifies the direct rate of working by the source on the resultant field, is described and illustrated for both point and continuous source distribution. A comparison between the respective procedures is made in the analysis of sound radiated from a periodic dipole source whose axis performs a periodic plane angular movement about a fixed direction. Thus, adopting a conventional approach, Sretenskii (1956) characterizes the rotating dipole in terms of an infinite number of stationary ones along a pari of orthogonal directions in the plane, and through the far field representation of the latter, arrives at a series development for the instantaneous radiated power, whereas the local manner of power calculation dispenses with the equivalent infinite aggregate of sources and yields a compact analytical result.

Levine, H.

1980-01-01

450

Biochemistry of ionizing radiation  

SciTech Connect

This volume examines the biochemical changes occurring in normal tissue after irradiation. A review of radiation chemistry is followed by an analysis of factors affecting biochemical responses and a timely discussion of radiobiology in space flight. The authors then describe the effects of radiation on lipid peroxidation, amino acids, peptides, proteins, polysaccharides, DNA, thiols, and body fluids. Close attention is given to alterations in biological mediators such as eicosanoids, cyclic nucleotides, angiotensin, histamine, polyamines, catecholamines, and serotonin and in hormones such as adrenocorticotropic hormone, testosterone, estrogens, follicle-stimulating hormone, luteinizing hormone, thyroid hormones, insulin and glucagon, gastrin, and melatonin. Other chapters focus on changes in carbohydrate metabolism, oxidative phosphorylation, protein synthesis, and serum proteins. A chapter on biological dosimeters discusses prodromal syndrome, hematological dosimeters, serum composition, urine, chromosomal aberrations, and fluorometric and immunoassays.

Walden, T.L.; Nushin, F.K.

1990-01-01

451

Radiation Therapy: Preventing and Managing Side Effects  

MedlinePLUS

... effects of radiation therapy Preventing and managing side effects of radiation therapy When the radiation damages nearby ... radiation therapy ” section for more on this. Side effects can vary. Your doctor and nurse are the ...

452

The radiation hazard during space flights  

NASA Technical Reports Server (NTRS)

Galactic cosmic radiation is described. Distinctive features of radiation effects in space flights are discussed and space radiation hazards are estimated. Measures to provide radiation safety during space flights are given. The need for safety standards is emphasized.

Kovalev, Y. Y.; Kolomenskiy, A. V.; Smirennyy, L. N.; Petrov, V. M.

1973-01-01

453

RADIATION PERMIT APPLICATION Western Human Resources  

E-print Network

1 RADIATION PERMIT APPLICATION Western Human Resources Occupational Health & Safety Please complete the information and send to: Hoa Ly Radiation Safety Coordinator Occupational Health and Safety Room 4190, Support: ________________________ Fax: ___________________________________ Radiation Safety Training and Radiation Work Experience 1

Sinnamon, Gordon J.

454

Provisional standards of radiation safety during flights  

NASA Technical Reports Server (NTRS)

Radiation effects during space flights are discussed in the context of the sources and dangers of such radiation and the radiobiological prerequisites for establishing safe levels of radiation dosage. Standard safe levels of radiation during space flight are established.

1977-01-01

455

Solar Radiation Resource Information  

NSDL National Science Digital Library

This is the Solar Radiation Resource Information page for the RReDC which provides information on several types of renewable energy resources in the United States, in the form of publications, data, and maps. An extensive dictionary of renewable energy related terms is also provided. This page has links to: -Archived Data -NREL Data Collection Activities -Solar Spectra -Solar Codes & Algorithms -Solar Models -Solar Calculators -Publications. Keyword: Photovoltaic, cell, PV.

2012-10-15

456

Radiation in Yolo County  

NASA Astrophysics Data System (ADS)

In today's post-nuclear age, there are many man-made sources of radioactivity, in addition to the natural background we expect from cosmic and terrestrial origins. While all atoms possess unstable isotopes, there are few that are abundant enough, energetic enough, and have long enough half-lives to pose a signicant risk of ionizing radiation exposure. We hypothesize a decreasing relative radiation measurement (in detected counts per minute [CPM]) at nine locations that might pose occupational or environmental hazard: 1. A supermarket produce aisle (living tissue has high concentration of 40K) 2. A hospital (medical imaging uses X-rays and radioactive dyes) 3. The electronics section of a superstore (high voltage electronics have the potential to produce ionizing radiation) 4. An electrical transformer (similar reasons) 5. An antique store (some ceramics and glazes use radioisotopes that are now outlawed) 6. A gasoline pump (processing and terrestrial isotope contamination might leave a radioactive residue) 7. A fertilized eld (phosphate rock contains uranium and thorium, in addition to potassium) 8. A house (hopefully mild background, but potential radon contamination) 9. A school (should be radiologically neutral) We tested the hypothesis by measuring 100 minutes of counts on a self-assembled MightyOhmTM Geiger counter at each location. Our results show that contrary to the hypothesized ordering, the house was the most radiologically active. We present possible explanations for the observed radiation levels, as well as possible sources of measurement error, possible consequences of prolonged exposure to the measured levels, and suggestions for decreasing exposure and environmental impact.

Dickie, H.; Colwell, K.

2013-12-01

457

Radiation-driven inflation  

SciTech Connect

A novel, scalar-field-free approach to cosmic inflation is presented. The inflationary Universe and the radiation-dominated Universe are shown, within the framework of unified brane cosmology, to be two different phases governed by one and the same energy density. The phase transition of second order (the Hubble constant exhibits a finite jump) appears naturally and serves as the exit mechanism. No re-heating is needed. The required number of e-folds is achieved without fine tuning.

Davidson, Aharon; Gurwich, Ilya, E-mail: davidson@bgu.ac.il, E-mail: gurwichphys@gmail.com, E-mail: ilyagur@gmail.com [Physics Department, Ben-Gurion University, Beer-Sheva 84105 (Israel)] [Physics Department, Ben-Gurion University, Beer-Sheva 84105 (Israel)

2008-06-15

458

Caenorhabditis elegans Radiation Responses  

Microsoft Academic Search

\\u000a Over the past 10 years a number of laboratories have started to focus on Caenorhabditis elegans radiation responses, taking advantage of a multi-cellular experimental model system that enables studying DNA damage responses\\u000a at the organismal level. Here we provide a comprehensive review of C. elegans DNA damage responses, largely focusing on recombinational repair, DNA damage signalling and DNA damage-