Dose conversion coefficients for high-energy photons, electrons, neutrons and protons

CERN Document Server

Sakamoto, Y; Sato, O; Tanaka, S I; Tsuda, S; Yamaguchi, Y; Yoshizawa, N

2003-01-01

In the International Commission on Radiological Protection (ICRP) 1990 Recommendations, radiation weighting factors were introduced in the place of quality factors, the tissue weighting factors were revised, and effective doses and equivalent doses of each tissues and organs were defined as the protection quantities. Dose conversion coefficients for photons, electrons and neutrons based on new ICRP recommendations were cited in the ICRP Publication 74, but the energy ranges of theses data were limited and there are no data for high energy radiations produced in accelerator facilities. For the purpose of designing the high intensity proton accelerator facilities at JAERI, the dose evaluation code system of high energy radiations based on the HERMES code was developed and the dose conversion coefficients of effective dose were evaluated for photons, neutrons and protons up to 10 GeV, and electrons up to 100 GeV. The dose conversion coefficients of effective dose equivalent were also evaluated using quality fact...

Calculation of conversion coefficients for clinical photon spectra using the MCNP code.

Science.gov (United States)

Lima, M A F; Silva, A X; Crispim, V R

2004-01-01

In this work, the MCNP4B code has been employed to calculate conversion coefficients from air kerma to the ambient dose equivalent, H*(10)/Ka, for monoenergetic photon energies from 10 keV to 50 MeV, assuming the kerma approximation. Also estimated are the H*(10)/Ka for photon beams produced by linear accelerators, such as Clinac-4 and Clinac-2500, after transmission through primary barriers of radiotherapy treatment rooms. The results for the conversion coefficients for monoenergetic photon energies, with statistical uncertainty <2%, are compared with those in ICRP publication 74 and good agreements were obtained. The conversion coefficients calculated for real clinic spectra transmitted through walls of concrete of 1, 1.5 and 2 m thick, are in the range of 1.06-1.12 Sv Gy(-1).

Extending the Constant Coefficient Solution Technique to Variable Coefficient Ordinary Differential Equations

Science.gov (United States)

Mohammed, Ahmed; Zeleke, Aklilu

2015-01-01

We introduce a class of second-order ordinary differential equations (ODEs) with variable coefficients whose closed-form solutions can be obtained by the same method used to solve ODEs with constant coefficients. General solutions for the homogeneous case are discussed.

Determination of fluence-to-dose conversion coefficients by means of artificial neural networks

International Nuclear Information System (INIS)

Soto B, T. G.; Rivera P, E.; De Leon M, H. A.; Hernandez D, V. M.; Vega C, H. R.; Gallego, E.; Lorente, A.

2012-10-01

In this paper is presented an Artificial Neural Network (Ann) that has been designed, trained and validated to determinate the effective dose e, ambient dose equivalent h(10) and personal dose equivalent hp(10,θ) fluence-to-dose conversion coefficients at different positions, having as only input data 7 count rates obtained with a Bonner Sphere Spectrometer (Bss) system. A set of 211 neutron spectra and the fluence-to-dose conversion coefficients published by the International Atomic Energy Agency were used to train and validate the Ann. This set was divided into 2 subsets, one of 181 elements to train the Ann and the remaining 30 to validate it. The Ann was trained using Bss count rates as input data and the fluence-to-dose conversion coefficients as output data. The network was validated and tested with the set of 30 elements that were not used during the training process. Good results were obtained proving that Ann are a good choice for calculating the fluence-to-dose conversion coefficients having as only data the count rates obtained with a Bss. (Author)

Determination of fluence-to-dose conversion coefficients by means of artificial neural networks

Energy Technology Data Exchange (ETDEWEB)

Soto B, T. G.; Rivera P, E.; De Leon M, H. A.; Hernandez D, V. M.; Vega C, H. R. [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas (Mexico); Gallego, E.; Lorente, A., E-mail: tzinnia.soto@gmail.com [Universidad Politecnica de Madrid, Departamento de Ingenieria Nuclear, Jose Gutierrez Abascal No. 2, 28006 Madrid (Spain)

2012-10-15

In this paper is presented an Artificial Neural Network (Ann) that has been designed, trained and validated to determinate the effective dose e, ambient dose equivalent h(10) and personal dose equivalent hp(10,{theta}) fluence-to-dose conversion coefficients at different positions, having as only input data 7 count rates obtained with a Bonner Sphere Spectrometer (Bss) system. A set of 211 neutron spectra and the fluence-to-dose conversion coefficients published by the International Atomic Energy Agency were used to train and validate the Ann. This set was divided into 2 subsets, one of 181 elements to train the Ann and the remaining 30 to validate it. The Ann was trained using Bss count rates as input data and the fluence-to-dose conversion coefficients as output data. The network was validated and tested with the set of 30 elements that were not used during the training process. Good results were obtained proving that Ann are a good choice for calculating the fluence-to-dose conversion coefficients having as only data the count rates obtained with a Bss. (Author)

CALCULATION OF FLUENCE-TO-EFFECTIVE DOSE CONVERSION COEFFICIENTS FOR THE OPERATIONAL QUANTITY PROPOSED BY ICRU RC26.

Science.gov (United States)

Endo, Akira

2017-07-01

Fluence-to-effective dose conversion coefficients have been calculated for photons, neutrons, electrons, positrons, protons, muons, pions and helium ions for various incident angles of radiations. The aim of this calculation is to provide a set of conversion coefficients to the Report Committee 26 (RC26) of the International Commission on Radiation Units and Measurements (ICRU) for use in defining personal dose equivalent for individual monitoring. The data sets comprise effective dose conversion coefficients for incident angles of radiations from 0° to ±90° in steps of 15° and at ±180°. Conversion coefficients for rotational, isotropic, superior hemisphere semi-isotropic and inferior hemisphere semi-isotropic irradiations are also included. Numerical data of the conversion coefficients are presented as supplementary data. The conversion coefficients are used to define the personal dose equivalent, which is being considered by the ICRU RC26, as the operational quantity for individual monitoring. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Photon dose conversion coefficients for the human teeth in standard irradiation geometries

Energy Technology Data Exchange (ETDEWEB)

Ulanovsky, A; Wieser, A; Zankl, M; Jacob, P

2005-07-01

Photon dose conversion coefficients for the human tooth materials are computed in energy range from 0.01 to 10 MeV by the Monte Carlo method. The voxel phantom Golem of the human body with newly defined tooth region and a modified version of the EGS4 code have been used to compute the coefficients for 30 tooth cells with different locations and materials. The dose responses are calculated for cells representing buccal and lingual enamel layers. The computed coefficients demonstrate a strong dependence on energy and geometry of the radiation source and a weaker dependence on location of the enamel voxels. For isotropic and rotational radiation fields the enamel dose does not show a significant dependence on tooth sample locations. The computed coefficients are used to convert from absorbed dose in teeth to organ dose or to integral air kerma. Examples of integral conversion factors from enamel dose to air kerma are given for several photon fluences specific for the Mayak reprocessing plant in Russia. The integral conversion factors are strongly affected by the energy and angular distributions of photon fluence, which are important characteristics of an exposure scenario for reconstruction of individual occupational doses. (orig.)

Overview of the ICRP/ICRU adult reference computational phantoms and dose conversion coefficients for external idealised exposures

CERN Document Server

Endo, A; Zankl, M; Bolch, W E; Eckerman, K F; Hertel, N E; Hunt, J G; Pelliccioni, M; Schlattl, H; Menzel, H-G

2014-01-01

This paper reviews the ICRP Publications 110 and 116 describing the reference computational phantoms and dose conversion coefficients for external exposures. The International Commission on Radiological Protection (ICRP) in its 2007 Recommendations made several revisions to the methods of calculation of the protection quantities. In order to implement these recommendations, the DOCAL task group of the ICRP developed computational phantoms representing the reference adult male and female and then calculated a set of dose conversion coefficients for various types of idealised external exposures. This paper focuses on the dose conversion coefficients for neutrons and investigates their relationship with the conversion coefficients of the protection and operational quantities of ICRP Publication 74. Contributing factors to the differences between these sets of conversion coefficients are discussed in terms of the changes in phantoms employed and the radiation and tissue weighting factors.

Conversion coefficients for individual monitoring calculated with integrated tiger series, ITS3, Monte Carlo code

International Nuclear Information System (INIS)

Devine, R.T.; Hsu, Hsiao-Hua

1994-01-01

The current basis for conversion coefficients for calibrating individual photon dosimeters in terms of dose equivalents is found in the series of papers by Grosswent. In his calculation the collision kerma inside the phantom is determined by calculation of the energy fluence at the point of interest and the use of the mass energy absorption coefficient. This approximates the local absorbed dose. Other Monte Carlo methods can be sued to provide calculations of the conversion coefficients. Rogers has calculated fluence-to-dose equivalent conversion factors with the Electron-Gamma Shower Version 3, EGS3, Monte Carlo program and produced results similar to Grosswent's calculations. This paper will report on calculations using the Integrated TIGER Series Version 3, ITS3, code to calculate the conversion coefficients in ICRU Tissue and in PMMA. A complete description of the input parameters to the program is given and comparison to previous results is included

Simulation codes to evcaluate dose conversion coefficients for hadrons over 10 GeV

International Nuclear Information System (INIS)

Sato, T.; Tsuda, S.; Sakamoto, Y.; Yamaguchi, Y.; Niita, K.

2002-01-01

The conversion coefficients from fluence to effective dose for high energy hadrons are indispensable for various purposes such as accelerator shielding design and dose evaluation in space mission. Monte Carlo calculation code HETC-3STEP was used to evaluate dose conversion coefficients for neutrons and protons up to 10 GeV with an anthropomorphic model. The scaling model was incorporated in the code for simulation of high energy nuclear reactions. However, the secondary particle energy spectra predicted by the model were not smooth for nuclear reactions over several GeV. We attempted, therefore, to simulate transportation of such high energy particles by two newly developed Monte Carlo simulation codes: one is HETC-3STEP including the model used in EVENTQ instead of the scaling model, and the other is NMTC/JAM. By comparing calculated cross sections by these codes with experimental data for high energy nuclear reactions, it was found that NMTC/JAM had a better agreement with the data. We decided, therefore, to adopt NMTC/JAM for evaluation of dose conversion coefficients for hadrons with energies over 10 GeV. The effective dose conversion coefficients for high energy neutrons and protons evaluated by NMTC/JAM were found to be close to those by the FLUKA code

Overview of the ICRP/ICRU adult reference computational phantoms and dose conversion coefficients for external idealised exposures

International Nuclear Information System (INIS)

Endo, Akira; Petoussi-Henss, Nina; Zankl, Maria; Schlattl, Helmut; Bolch, Wesley E.; Eckerman, Keith F.; Hertel, Nolan E.; Hunt, John G.; Pelliccioni, Maurizio; Menzel, Hans-Georg

2014-01-01

This paper reviews the ICRP Publications 110 and 116 describing the reference computational phantoms and dose conversion coefficients for external exposures. The International Commission on Radiological Protection (ICRP) in its 2007 Recommendations made several revisions to the methods of calculation of the protection quantities. In order to implement these recommendations, the DOCAL task group of the ICRP developed computational phantoms representing the reference adult male and female and then calculated a set of dose conversion coefficients for various types of idealised external exposures. This paper focuses on the dose conversion coefficients for neutrons and investigates their relationship with the conversion coefficients of the protection and operational quantities of ICRP Publication 74. Contributing factors to the differences between these sets of conversion coefficients are discussed in terms of the changes in phantoms employed and the radiation and tissue weighting factors. This paper briefly reviews the reference computational phantoms and dose conversion coefficients for external exposures that were published jointly by ICRP and ICRU. Both these publications appeared as a consequence of the ICRP 2007 Recommendations; to implement these recommendations, the ICRP has developed reference computational phantoms representing the adult male and female. These phantoms are used to calculate reference dose conversion coefficients for external and internal sources. Using the reference phantoms and methodology consistent with the 2007 Recommendations, dose conversion coefficients for both effective doses and organ-absorbed doses for various types of idealised external exposures have been calculated. These data sets supersede the existing ICRP/ICRU data sets and expand the particle types and energy ranges. For neutrons, the new effective dose conversion coefficients become smaller compared with those in ICRP74, for energies below hundreds of keV. This is mainly

Fluence to Dose Equivalent Conversion Coefficients for Evaluation of Accelerator Radiation Environments

International Nuclear Information System (INIS)

Thomas, Ralph H.; Zeman, Gary H.

2001-01-01

The derivation of a set of conversion functions for the expression of neutron fluence measurements in terms of Effective Dose, E, is described. Four functions in analytical form are presented, covering the neutron energy range from 2.5 10-8 to 10+4 MeV, for the interpretation of fluence measurements in the typical irradiation conditions experienced around high-energy proton accelerators such as the Bevatron. For neutron energies below 200 MeV the analytical functions were modeled after the ISO and ROT conversion coefficients in ICRU 57. For neutron energies above 200 MeV, the analytical function was derived from an analysis of recent published data. Sample calculations using either the analytical expressions or the tabulated conversion coefficients from which the analytical expressions are derived show agreement to better than plus/minus 5%

Conversion coefficients for determining organ doses in paediatric pelvis and hip joint radiography

International Nuclear Information System (INIS)

Seidenbusch, Michael C.; Schneider, Karl

2014-01-01

Knowledge of organ and effective doses achieved during paediatric X-ray examinations is an important prerequisite for assessment of radiation burden to the patient. Conversion coefficients for reconstruction of organ and effective doses from entrance doses for pelvis and hip joint radiographs of 0-, 1-, 5-, 10-, 15- and 30-year-old patients are provided regarding the Guidelines of Good Radiographic Technique of the European Commission. Using the personal computer program PCXMC developed by the Finnish Centre for Radiation and Nuclear Safety (Saeteilyturvakeskus STUK), conversion coefficients for conventional pelvis and hip joint radiographs were calculated by performing Monte Carlo simulations in mathematical hermaphrodite phantom models representing patients of different ages. The clinical variation of radiation field settings was taken into consideration by defining optimal and suboptimal standard field settings. Conversion coefficients for the reconstruction of organ doses in about 40 organs and tissues from measured entrance doses during pelvis and hip joint radiographs of 0-, 1-, 5-, 10-, 15- and 30-year-old patients were calculated for the standard sagittal beam projection and the standard focus detector distance of 115 cm. The conversion coefficients presented can be used for organ dose assessments from entrance doses measured during pelvis and hip joint radiographs of children and young adults with all field settings within the optimal and suboptimal standard field settings. (orig.)

Formulae of differentiation for solving differential equations with complex-valued random coefficients

International Nuclear Information System (INIS)

Kim, Ki Hong; Lee, Dong Hun

1999-01-01

Generalizing the work of Shapiro and Loginov, we derive new formulae of differentiation useful for solving differential equations with complex-valued random coefficients. We apply the formulae to the quantum-mechanical problem of noninteracting electrons moving in a correlated random potential in one dimension

Internal Dose Conversion Coefficients of Domestic Reference Animal and Plants for Dose Assessment of Non-human Species

International Nuclear Information System (INIS)

Keum, Dong Kwon; Jun, In; Lim, Kwang Muk; Choi, Yong Ho

2009-01-01

Traditionally, radiation protection has been focused on a radiation exposure of human beings. In the international radiation protection community, one of the recent key issues is to establish the methodology for assessing the radiological impact of an ionizing radiation on non-human species for an environmental protection. To assess the radiological impact to non-human species dose conversion coefficients are essential. This paper describes the methodology to calculate the internal dose conversion coefficient for non-human species and presents calculated internal dose conversion coefficients of 25 radionuclides for 8 domestic reference animal and plants

Organ dose conversion coefficients for voxel models of the reference male and female from idealized photon exposures

Science.gov (United States)

Schlattl, H.; Zankl, M.; Petoussi-Henss, N.

2007-04-01

A new series of organ equivalent dose conversion coefficients for whole body external photon exposure is presented for a standardized couple of human voxel models, called Rex and Regina. Irradiations from broad parallel beams in antero-posterior, postero-anterior, left- and right-side lateral directions as well as from a 360° rotational source have been performed numerically by the Monte Carlo transport code EGSnrc. Dose conversion coefficients from an isotropically distributed source were computed, too. The voxel models Rex and Regina originating from real patient CT data comply in body and organ dimensions with the currently valid reference values given by the International Commission on Radiological Protection (ICRP) for the average Caucasian man and woman, respectively. While the equivalent dose conversion coefficients of many organs are in quite good agreement with the reference values of ICRP Publication 74, for some organs and certain geometries the discrepancies amount to 30% or more. Differences between the sexes are of the same order with mostly higher dose conversion coefficients in the smaller female model. However, much smaller deviations from the ICRP values are observed for the resulting effective dose conversion coefficients. With the still valid definition for the effective dose (ICRP Publication 60), the greatest change appears in lateral exposures with a decrease in the new models of at most 9%. However, when the modified definition of the effective dose as suggested by an ICRP draft is applied, the largest deviation from the current reference values is obtained in postero-anterior geometry with a reduction of the effective dose conversion coefficient by at most 12%.

Organ dose conversion coefficients for voxel models of the reference male and female from idealized photon exposures

International Nuclear Information System (INIS)

Schlattl, H; Zankl, M; Petoussi-Henss, N

2007-01-01

A new series of organ equivalent dose conversion coefficients for whole body external photon exposure is presented for a standardized couple of human voxel models, called Rex and Regina. Irradiations from broad parallel beams in antero-posterior, postero-anterior, left- and right-side lateral directions as well as from a 360 deg. rotational source have been performed numerically by the Monte Carlo transport code EGSnrc. Dose conversion coefficients from an isotropically distributed source were computed, too. The voxel models Rex and Regina originating from real patient CT data comply in body and organ dimensions with the currently valid reference values given by the International Commission on Radiological Protection (ICRP) for the average Caucasian man and woman, respectively. While the equivalent dose conversion coefficients of many organs are in quite good agreement with the reference values of ICRP Publication 74, for some organs and certain geometries the discrepancies amount to 30% or more. Differences between the sexes are of the same order with mostly higher dose conversion coefficients in the smaller female model. However, much smaller deviations from the ICRP values are observed for the resulting effective dose conversion coefficients. With the still valid definition for the effective dose (ICRP Publication 60), the greatest change appears in lateral exposures with a decrease in the new models of at most 9%. However, when the modified definition of the effective dose as suggested by an ICRP draft is applied, the largest deviation from the current reference values is obtained in postero-anterior geometry with a reduction of the effective dose conversion coefficient by at most 12%

VODE, Variable Coefficient Ordinary Differential Equations (ODE) Solver

International Nuclear Information System (INIS)

Brown, P.N.; Hindmarsh, A.C.; Byrne, G.D.

2002-01-01

1 - Description of program or function: VODE is a package of subroutines for the numerical solution of the initial-value problem for systems of first-order ordinary differential equations. The package can be used for either stiff or non-stiff systems. In the stiff case, the Jacobian matrix is treated as full or banded. An algorithm is included for saving and reusing the Jacobian matrix under certain conditions. If storage is limited, this option may be suppressed. 2 - Method of solution - VODE uses the variable-order, variable- coefficient Adams-Moulton method for non-stiff systems and the variable-order, fixed-leading-coefficient Backward Differentiation Formula (BDF) method for stiff systems

Linear mode conversion in a toroidal plasma

International Nuclear Information System (INIS)

Hellsten, T.

1980-05-01

Linear mode conversion at the perpendicular ion cyclotron resonance has been treated for an axially symmetric toroidal plasma. The mode conversion appears between a fast electromagnetic wave and a slow-quasi electrostatic wave, due to finite electron inertia. The problem reduces to the Orr-Sommerfeld equation where the coefficients determining the reflectron, transmission and conversion are functions of the arc length along a poloidal intersection of the resonance surface. These coefficients can be determined from eigenfunctions of an ordinary differential equation. (author)

New quantities in radiation protection and conversion coefficients

International Nuclear Information System (INIS)

1986-01-01

Four new quantities have been proposed by the ICRP for use in radiation protection from external sources, i.e. the ambient dose equivalent, the directional dose equivalent, the individual dose equivalent (penetrating), and the individual dose equivalent (superficial). These quantities are briefly described together with two new concepts of expanded and aligned fields. The BCRU recommends that these quantities should be adopted for use in the UK together with conversion coefficients when re-calibrating existing instruments, reporting the results of measurements and designing instruments. (UK)

Theoretical expression of the internal conversion coefficient of a M1 transition between two atomic states

International Nuclear Information System (INIS)

Attallah, F.; Chemin, J.F.; Scheurer, J.N.; Karpeshin, F.; Harston, M.

1997-01-01

We have established a general relation for the expression of the internal conversion of an M 1 transition a 1s electronic state to an empty ns electronic bound state. Under the hypothesis that the density of the electron level ρ n satisfies the condition ρ n Γ >> 1 (where Γ is the total width of the excited atomic state) a calculation in the first order gives a relation for the internal conversion coefficient.This relation shows that the internal conversion coefficient takes a resonant character when the nuclear energy transition is smaller than the binding energy of the 1s electron. An application of this relation to an M 1 transition in the case of the ion 125 T e with a charge state Q = 45 and an 1s electron binding energy E B 45 = 35.581 KeV gives the value for the internal conversion coefficient R = 5.7

Estimating varying coefficients for partial differential equation models.

Science.gov (United States)

Zhang, Xinyu; Cao, Jiguo; Carroll, Raymond J

2017-09-01

Partial differential equations (PDEs) are used to model complex dynamical systems in multiple dimensions, and their parameters often have important scientific interpretations. In some applications, PDE parameters are not constant but can change depending on the values of covariates, a feature that we call varying coefficients. We propose a parameter cascading method to estimate varying coefficients in PDE models from noisy data. Our estimates of the varying coefficients are shown to be consistent and asymptotically normally distributed. The performance of our method is evaluated by a simulation study and by an empirical study estimating three varying coefficients in a PDE model arising from LIDAR data. © 2017, The International Biometric Society.

Dose conversion coefficients for photon exposure of the human eye lens

Science.gov (United States)

Behrens, R.; Dietze, G.

2011-01-01

In recent years, several papers dealing with the eye lens dose have been published, because epidemiological studies implied that the induction of cataracts occurs even at eye lens doses of less than 500 mGy. Different questions were addressed: Which personal dose equivalent quantity is appropriate for monitoring the dose to the eye lens? Is a new definition of the dose quantity Hp(3) based on a cylinder phantom to represent the human head necessary? Are current conversion coefficients from fluence to equivalent dose to the lens sufficiently accurate? To investigate the latter question, a realistic model of the eye including the inner structure of the lens was developed. Using this eye model, conversion coefficients for electrons have already been presented. In this paper, the same eye model—with the addition of the whole body—was used to calculate conversion coefficients from fluence (and air kerma) to equivalent dose to the lens for photon radiation from 5 keV to 10 MeV. Compared to the values adopted in 1996 by the International Commission on Radiological Protection (ICRP), the new values are similar between 40 keV and 1 MeV and lower by up to a factor of 5 and 7 for photon energies at about 10 keV and 10 MeV, respectively. Above 1 MeV, the new values (calculated without kerma approximation) should be applied in pure photon radiation fields, while the values adopted by the ICRP in 1996 (calculated with kerma approximation) should be applied in case a significant contribution from secondary electrons originating outside the body is present.

Dose conversion coefficients for photon exposure of the human eye lens

International Nuclear Information System (INIS)

Behrens, R; Dietze, G

2011-01-01

In recent years, several papers dealing with the eye lens dose have been published, because epidemiological studies implied that the induction of cataracts occurs even at eye lens doses of less than 500 mGy. Different questions were addressed: Which personal dose equivalent quantity is appropriate for monitoring the dose to the eye lens? Is a new definition of the dose quantity H p (3) based on a cylinder phantom to represent the human head necessary? Are current conversion coefficients from fluence to equivalent dose to the lens sufficiently accurate? To investigate the latter question, a realistic model of the eye including the inner structure of the lens was developed. Using this eye model, conversion coefficients for electrons have already been presented. In this paper, the same eye model-with the addition of the whole body-was used to calculate conversion coefficients from fluence (and air kerma) to equivalent dose to the lens for photon radiation from 5 keV to 10 MeV. Compared to the values adopted in 1996 by the International Commission on Radiological Protection (ICRP), the new values are similar between 40 keV and 1 MeV and lower by up to a factor of 5 and 7 for photon energies at about 10 keV and 10 MeV, respectively. Above 1 MeV, the new values (calculated without kerma approximation) should be applied in pure photon radiation fields, while the values adopted by the ICRP in 1996 (calculated with kerma approximation) should be applied in case a significant contribution from secondary electrons originating outside the body is present.

Dose conversion coefficients for electron exposure of the human eye lens

International Nuclear Information System (INIS)

Behrens, R; Dietze, G; Zankl, M

2009-01-01

Recent epidemiological studies suggest a rather low dose threshold (below 0.5 Gy) for the induction of a cataract of the eye lens. Some other studies even assume that there is no threshold at all. Therefore, protection measures have to be optimized and current dose limits for the eye lens may be reduced in the future. Two questions arise from this situation: first, which dose quantity is related to the risk of developing a cataract, and second, which personal dose equivalent quantity is appropriate for monitoring this dose quantity. While the dose equivalent quantity H p (0.07) has often been seen as being sufficiently accurate for monitoring the dose to the lens of the eye, this would be questionable in the case when the dose limits were reduced and, thus, it may be necessary to generally use the dose equivalent quantity H p (3) for this purpose. The basis for a decision, however, must be the knowledge of accurate conversion coefficients from fluence to equivalent dose to the lens. This is especially important for low-penetrating radiation, for example, electrons. Formerly published values of conversion coefficients are based on quite simple models of the eye. In this paper, quite a sophisticated model of the eye including the inner structure of the lens was used for the calculations and precise conversion coefficients for electrons with energies between 0.2 MeV and 12 MeV, and for angles of radiation incidence between 0 deg. and 45 deg. are presented. Compared to the values adopted in 1996 by the International Commission on Radiological Protection (ICRP), the new values are up to 1000 times smaller for electron energies below 1 MeV, nearly equal at 1 MeV and above 4 MeV, and by a factor of 1.5 larger at about 1.5 MeV electron energy.

Dose conversion coefficients based on the Chinese mathematical phantom and MCNP code for external photon irradiation

International Nuclear Information System (INIS)

Qiu, R.; Li, J.; Zhang, Z.; Liu, L.; Bi, L.; Ren, L.

2009-01-01

A set of conversion coefficients from kerma free-in-air to the organ-absorbed dose are presented for external monoenergetic photon beams from 10 keV to 10 MeV based on the Chinese mathematical phantom, a whole-body mathematical phantom model. The model was developed based on the methods of the Oak Ridge National Laboratory mathematical phantom series and data from the Chinese Reference Man and the Reference Asian Man. This work is carried out to obtain the conversion coefficients based on this model, which represents the characteristics of the Chinese population, as the anatomical parameters of the Chinese are different from those of Caucasians. Monte Carlo simulation with MCNP code is carried out to calculate the organ dose conversion coefficients. Before the calculation, the effects from the physics model and tally type are investigated, considering both the calculation efficiency and precision. In the calculation irradiation conditions include anterior-posterior, posterior-anterior, right lateral, left lateral, rotational and isotropic geometries. Conversion coefficients from this study are compared with those recommended in the Publication 74 of International Commission on Radiological Protection (ICRP74) since both the sets of data are calculated with mathematical phantoms. Overall, consistency between the two sets of data is observed and the difference for more than 60% of the data is below 10%. However, significant deviations are also found, mainly for the superficial organs (up to 65.9%) and bone surface (up to 66%). The big difference of the dose conversion coefficients for the superficial organs at high photon energy could be ascribed to kerma approximation for the data in ICRP74. Both anatomical variations between races and the calculation method contribute to the difference of the data for bone surface. (authors)

Dose conversion coefficients based on the Chinese mathematical phantom and MCNP code for external photon irradiation.

Science.gov (United States)

Qiu, Rui; Li, Junli; Zhang, Zhan; Liu, Liye; Bi, Lei; Ren, Li

2009-02-01

A set of conversion coefficients from kerma free-in-air to the organ-absorbed dose are presented for external monoenergetic photon beams from 10 keV to 10 MeV based on the Chinese mathematical phantom, a whole-body mathematical phantom model. The model was developed based on the methods of the Oak Ridge National Laboratory mathematical phantom series and data from the Chinese Reference Man and the Reference Asian Man. This work is carried out to obtain the conversion coefficients based on this model, which represents the characteristics of the Chinese population, as the anatomical parameters of the Chinese are different from those of Caucasians. Monte Carlo simulation with MCNP code is carried out to calculate the organ dose conversion coefficients. Before the calculation, the effects from the physics model and tally type are investigated, considering both the calculation efficiency and precision. In the calculation irradiation conditions include anterior-posterior, posterior-anterior, right lateral, left lateral, rotational and isotropic geometries. Conversion coefficients from this study are compared with those recommended in the Publication 74 of International Commission on Radiological Protection (ICRP74) since both the sets of data are calculated with mathematical phantoms. Overall, consistency between the two sets of data is observed and the difference for more than 60% of the data is below 10%. However, significant deviations are also found, mainly for the superficial organs (up to 65.9%) and bone surface (up to 66%). The big difference of the dose conversion coefficients for the superficial organs at high photon energy could be ascribed to kerma approximation for the data in ICRP74. Both anatomical variations between races and the calculation method contribute to the difference of the data for bone surface.

A generalized fractional sub-equation method for fractional differential equations with variable coefficients

International Nuclear Information System (INIS)

Tang, Bo; He, Yinnian; Wei, Leilei; Zhang, Xindong

2012-01-01

In this Letter, a generalized fractional sub-equation method is proposed for solving fractional differential equations with variable coefficients. Being concise and straightforward, this method is applied to the space–time fractional Gardner equation with variable coefficients. As a result, many exact solutions are obtained including hyperbolic function solutions, trigonometric function solutions and rational solutions. It is shown that the considered method provides a very effective, convenient and powerful mathematical tool for solving many other fractional differential equations in mathematical physics. -- Highlights: ► Study of fractional differential equations with variable coefficients plays a role in applied physical sciences. ► It is shown that the proposed algorithm is effective for solving fractional differential equations with variable coefficients. ► The obtained solutions may give insight into many considerable physical processes.

Internal and external dose conversion coefficient for domestic reference animals and plant

Energy Technology Data Exchange (ETDEWEB)

Keum, Dong Kwon; Jun, In; Lim, Kwang Muk; Park, Du Won; Choi, Young Ho

2009-07-15

This report presents the internal and external dose conversion coefficients for domestic reference animals and plant, which are essential to assess the radiological impact of an environmental radiation on non-human species. To calculate the dose conversion coefficients, a uniform isotropic model and a Monte Carlo method for a photon transport simulation in environmental media with different densities have been applied for aquatic and terrestrial animals, respectively. In the modeling all the target animals are defined as a simple 3D elliptical shape. To specify the external radiation source it is assumed that aquatic animals are fully immersed in infinite and uniformly contaminated water, and the on-soil animals are living on the surface of a horizontally infinite soil source, and the in-soil organisms are living at the center of a horizontally infinite and uniformly contaminated soil to a depth of 50cm. A set of internal and external dose conversion coefficients for 8 Korean reference animals and plant (rat, roe-deer, frog, snake, Chinese minnow, bee, earthworm, and pine tree) are presented for 25 radionuclides ({sup 3}H, {sup 7}Be, {sup 14}C, {sup 40}K, {sup 51}Cr, {sup 54}Mn, {sup 59}Fe, {sup 58}Co, {sup 60}Co, {sup 65}Zn, {sup 90}Sr, {sup 95}Zr, {sup 95}Nb, {sup 99}Tc, {sup 106}Ru, {sup 129}I, {sup 131}I, {sup 136}Cs, {sup 137}Cs, {sup 140}Ba, {sup 140}La, {sup 144}Ce, {sup 238}U, {sup 239}Pu, and {sup 240}Pu)

Outlines of ICRP publication 74 and new dose conversion coefficients for external radiation

International Nuclear Information System (INIS)

Yamaguchi, Yasuhiro

1998-01-01

Combined task group of ICRP and ICRU reported the ICRP Publication 74 (1996) which is a summary report of their collection, analysis and evaluation of many data and dose conversion coefficients. Concerning the new coefficients, the author described this review as follows: History until Publication 74. Doses recommended at present: for protection quantity, the mean absorption dose of organ and tissue, equivalent dose and effective dose and for operational quantity, the ambient dose equivalent, directional dose equivalent and individual dose equivalent. Changes which can have an influence on the dose evaluation; introduction of radiation weighting factor (WR), changing of tissue weighting factor (WR), changing of the equation for Q-L relation and updating of physical data. New dose conversion coefficients; for photon, neutron and electron. Comparison of new and present coefficients; concerning the quality factor Q, particularly for neutron Q. New relations of protection and operational quantities; for field and individual monitoring. General conclusion of Publication 74. The Publication gives a certain direction for problems in evaluation of external exposure dose which have been discussed since the ICRP Fundamental Recommendation 1990 was issued. However, there still remain many problems especially in validity of the WR and of equation for Q-L relation. (K.H.)

Dose conversion coefficients calculated using a series of adult Japanese voxel phantoms against external photon exposure

International Nuclear Information System (INIS)

Sato, Kaoru; Endo, Akira; Saito, Kimiaki

2008-10-01

This report presents a complete set of conversion coefficients of organ doses and effective doses calculated for external photon exposure using five Japanese adult voxel phantoms developed at the Japan Atomic Energy Agency (JAEA). At the JAEA, high-resolution Japanese voxel phantoms have been developed to clarify the variation of organ doses due to the anatomical characteristics of Japanese, and three male phantoms (JM, JM2 and Otoko) and two female phantoms (JF and Onago) have been constructed up to now. The conversion coefficients of organ doses and effective doses for the five voxel phantoms have been calculated for six kinds of idealized irradiation geometries from monoenergetic photons ranging from 0.01 to 10 MeV using EGS4, a Monte Carlo code for the simulation of coupled electron-photon transport. The dose conversion coefficients are given as absorbed dose and effective dose per unit air-kerma free-in-air, and are presented in tables and figures. The calculated dose conversion coefficients are compared with those of voxel phantoms based on the Caucasian and the recommended values in ICRP74 in order to discuss (1) variation of organ dose due to the body size and individual anatomy, such as position and shape of organs, and (2) effect of posture on organ doses. The present report provides valuable data to study the influence of the body characteristics of Japanese upon the organ doses and to discuss developing reference Japanese and Asian phantoms. (author)

Differentially expressed genes in iron-induced prion protein conversion

International Nuclear Information System (INIS)

Kim, Minsun; Kim, Eun-hee; Choi, Bo-Ran; Woo, Hee-Jong

2016-01-01

The conversion of the cellular prion protein (PrP C ) to the protease-resistant isoform is the key event in chronic neurodegenerative diseases, including transmissible spongiform encephalopathies (TSEs). Increased iron in prion-related disease has been observed due to the prion protein-ferritin complex. Additionally, the accumulation and conversion of recombinant PrP (rPrP) is specifically derived from Fe(III) but not Fe(II). Fe(III)-mediated PK-resistant PrP (PrP res ) conversion occurs within a complex cellular environment rather than via direct contact between rPrP and Fe(III). In this study, differentially expressed genes correlated with prion degeneration by Fe(III) were identified using Affymetrix microarrays. Following Fe(III) treatment, 97 genes were differentially expressed, including 85 upregulated genes and 12 downregulated genes (≥1.5-fold change in expression). However, Fe(II) treatment produced moderate alterations in gene expression without inducing dramatic alterations in gene expression profiles. Moreover, functional grouping of identified genes indicated that the differentially regulated genes were highly associated with cell growth, cell maintenance, and intra- and extracellular transport. These findings showed that Fe(III) may influence the expression of genes involved in PrP folding by redox mechanisms. The identification of genes with altered expression patterns in neural cells may provide insights into PrP conversion mechanisms during the development and progression of prion-related diseases. - Highlights: • Differential genes correlated with prion degeneration by Fe(III) were identified. • Genes were identified in cell proliferation and intra- and extracellular transport. • In PrP degeneration, redox related genes were suggested. • Cbr2, Rsad2, Slc40a1, Amph and Mvd were expressed significantly.

Organ dose conversion coefficients based on a voxel mouse model and MCNP code for external photon irradiation.

Science.gov (United States)

Zhang, Xiaomin; Xie, Xiangdong; Cheng, Jie; Ning, Jing; Yuan, Yong; Pan, Jie; Yang, Guoshan

2012-01-01

A set of conversion coefficients from kerma free-in-air to the organ absorbed dose for external photon beams from 10 keV to 10 MeV are presented based on a newly developed voxel mouse model, for the purpose of radiation effect evaluation. The voxel mouse model was developed from colour images of successive cryosections of a normal nude male mouse, in which 14 organs or tissues were segmented manually and filled with different colours, while each colour was tagged by a specific ID number for implementation of mouse model in Monte Carlo N-particle code (MCNP). Monte Carlo simulation with MCNP was carried out to obtain organ dose conversion coefficients for 22 external monoenergetic photon beams between 10 keV and 10 MeV under five different irradiation geometries conditions (left lateral, right lateral, dorsal-ventral, ventral-dorsal, and isotropic). Organ dose conversion coefficients were presented in tables and compared with the published data based on a rat model to investigate the effect of body size and weight on the organ dose. The calculated and comparison results show that the organ dose conversion coefficients varying the photon energy exhibits similar trend for most organs except for the bone and skin, and the organ dose is sensitive to body size and weight at a photon energy approximately <0.1 MeV.

An effective method for finding special solutions of nonlinear differential equations with variable coefficients

International Nuclear Information System (INIS)

Qin Maochang; Fan Guihong

2008-01-01

There are many interesting methods can be utilized to construct special solutions of nonlinear differential equations with constant coefficients. However, most of these methods are not applicable to nonlinear differential equations with variable coefficients. A new method is presented in this Letter, which can be used to find special solutions of nonlinear differential equations with variable coefficients. This method is based on seeking appropriate Bernoulli equation corresponding to the equation studied. Many well-known equations are chosen to illustrate the application of this method

SU-D-209-06: Study On the Dose Conversion Coefficients in Pediatric Radiography with the Development of Children Voxel Phantoms

Energy Technology Data Exchange (ETDEWEB)

Liu, Q [Institute of Radiation Medicine Fudan University, Shanghai (China); Shanghai General Hospital, Shanghai, Shanghai (China); Zhuo, W; Liu, H [Institute of Radiation Medicine Fudan University, Shanghai (China); Liu, Y; Chen, T [Shanghai General Hospital, Shanghai, Shanghai (China)

2016-06-15

Purpose: Conversion coefficients of organ dose normalized to entrance skin dose (ESD) are widely used to evaluate the organ doses directly using ESD without time-consuming dose measurement, this work aims to investigate the dose conversion coefficients in pediatric chest and abdomen radiography with the development of 5 years and 10 years old children voxel phantoms. Methods: After segmentation of organs and tissues from CT slice images of ATOM tissue-equivalent phantoms, a 5-year-old and a 10-year-old children computational voxel phantoms were developed for Monte Carlo simulation. The organ doses and the entrance skin dose for pediatric chest postero-anterior projection and abdominal antero-posterior projection were simulated at the same time, and then the organ dose conversion coefficients were calculated.To verify the simulated results, dose measurement was carried out with ATOM tissue-equivalent phantoms for 5 year chest radiography. Results: Simulated results and experimental results matched very well with each other, the result differences of all the organs covered in radiation field were below 16% for 5-year-old child in chest projection. I showed that the conversion coefficients of organs covered in the radiation field were much larger than organs out of the field for all the study cases, for example, the conversion coefficients of stomach, liver intestines, and pancreas are larger for abdomen radiography while conversion coefficients of lungs are larger for chest radiography. Conclusion: The voxel children phantoms were helpful to evaluate the radiation doses more accurately and efficiently. Radiation field was the essential factor that affects the organ dose, use reasonably small field should be encouraged for radiation protection. This work was supported by the National Natural Science Foundation of China(11475047)

SU-D-209-06: Study On the Dose Conversion Coefficients in Pediatric Radiography with the Development of Children Voxel Phantoms

International Nuclear Information System (INIS)

Liu, Q; Zhuo, W; Liu, H; Liu, Y; Chen, T

2016-01-01

Purpose: Conversion coefficients of organ dose normalized to entrance skin dose (ESD) are widely used to evaluate the organ doses directly using ESD without time-consuming dose measurement, this work aims to investigate the dose conversion coefficients in pediatric chest and abdomen radiography with the development of 5 years and 10 years old children voxel phantoms. Methods: After segmentation of organs and tissues from CT slice images of ATOM tissue-equivalent phantoms, a 5-year-old and a 10-year-old children computational voxel phantoms were developed for Monte Carlo simulation. The organ doses and the entrance skin dose for pediatric chest postero-anterior projection and abdominal antero-posterior projection were simulated at the same time, and then the organ dose conversion coefficients were calculated.To verify the simulated results, dose measurement was carried out with ATOM tissue-equivalent phantoms for 5 year chest radiography. Results: Simulated results and experimental results matched very well with each other, the result differences of all the organs covered in radiation field were below 16% for 5-year-old child in chest projection. I showed that the conversion coefficients of organs covered in the radiation field were much larger than organs out of the field for all the study cases, for example, the conversion coefficients of stomach, liver intestines, and pancreas are larger for abdomen radiography while conversion coefficients of lungs are larger for chest radiography. Conclusion: The voxel children phantoms were helpful to evaluate the radiation doses more accurately and efficiently. Radiation field was the essential factor that affects the organ dose, use reasonably small field should be encouraged for radiation protection. This work was supported by the National Natural Science Foundation of China(11475047)

Age-dependent conversion coefficients for organ doses and effective doses for external neutron irradiation

International Nuclear Information System (INIS)

Nishizaki, Chihiro; Endo, Akira; Takahashi, Fumiaki

2006-06-01

To utilize dose assessment of the public for external neutron irradiation, conversion coefficients of absorbed doses of organs and effective doses were calculated using the numerical simulation technique for six different ages (adult, 15, 10, 5 and 1 years and newborn), which represent the member of the public. Calculations were performed using six age-specific anthropomorphic phantoms and a Monte Carlo radiation transport code for two irradiation geometries, anterior-posterior and rotational geometries, for 20 incident energies from thermal to 20 MeV. Effective doses defined by the 1990 Recommendation of ICRP were calculated from the absorbed doses in 21 organs. The calculated results were tabulated in the form of absorbed doses and effective doses per unit neutron fluence. The calculated conversion coefficients are used for dose assessment of the public around nuclear facilities and accelerator facilities. (author)

The system of radiation dose assessment and dose conversion coefficients in the ICRP and FGR

Energy Technology Data Exchange (ETDEWEB)

Kim, So Ra; Min, Byung Il; Park, Kihyun; Yang, Byung Mo; Suh, Kyung Suk [Nuclear Environmental Safety Research Division, Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2016-12-15

The International Commission on Radiological Protection (ICRP) recommendations and the Federal Guidance Report (FGR) published by the U.S. Environmental Protection Agency (EPA) have been widely applied worldwide in the fields of radiation protection and dose assessment. The dose conversion coefficients of the ICRP and FGR are widely used for assessing exposure doses. However, before the coefficients are used, the user must thoroughly understand the derivation process of the coefficients to ensure that they are used appropriately in the evaluation. The ICRP provides recommendations to regulatory and advisory agencies, mainly in the form of guidance on the fundamental principles on which appropriate radiological protection can be based. The FGR provides federal and state agencies with technical information to assist their implementation of radiation protection programs for the U.S. population. The system of radiation dose assessment and dose conversion coefficients in the ICRP and FGR is reviewed in this study. A thorough understanding of their background is essential for the proper use of dose conversion coefficients. The FGR dose assessment system was strongly influenced by the ICRP and the U.S. National Council on Radiation Protection and Measurements (NCRP), and is hence consistent with those recommendations. Moreover, the ICRP and FGR both used the scientific data reported by Biological Effects of Ionizing Radiation (BEIR) and United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) as their primary source of information. The difference between the ICRP and FGR lies in the fact that the ICRP utilized information regarding a population of diverse races, whereas the FGR utilized data on the American population, as its goal was to provide guidelines for radiological protection in the US. The contents of this study are expected to be utilized as basic research material in the areas of radiation protection and dose assessment.

The system of radiation dose assessment and dose conversion coefficients in the ICRP and FGR

International Nuclear Information System (INIS)

Kim, So Ra; Min, Byung Il; Park, Kihyun; Yang, Byung Mo; Suh, Kyung Suk

2016-01-01

The International Commission on Radiological Protection (ICRP) recommendations and the Federal Guidance Report (FGR) published by the U.S. Environmental Protection Agency (EPA) have been widely applied worldwide in the fields of radiation protection and dose assessment. The dose conversion coefficients of the ICRP and FGR are widely used for assessing exposure doses. However, before the coefficients are used, the user must thoroughly understand the derivation process of the coefficients to ensure that they are used appropriately in the evaluation. The ICRP provides recommendations to regulatory and advisory agencies, mainly in the form of guidance on the fundamental principles on which appropriate radiological protection can be based. The FGR provides federal and state agencies with technical information to assist their implementation of radiation protection programs for the U.S. population. The system of radiation dose assessment and dose conversion coefficients in the ICRP and FGR is reviewed in this study. A thorough understanding of their background is essential for the proper use of dose conversion coefficients. The FGR dose assessment system was strongly influenced by the ICRP and the U.S. National Council on Radiation Protection and Measurements (NCRP), and is hence consistent with those recommendations. Moreover, the ICRP and FGR both used the scientific data reported by Biological Effects of Ionizing Radiation (BEIR) and United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) as their primary source of information. The difference between the ICRP and FGR lies in the fact that the ICRP utilized information regarding a population of diverse races, whereas the FGR utilized data on the American population, as its goal was to provide guidelines for radiological protection in the US. The contents of this study are expected to be utilized as basic research material in the areas of radiation protection and dose assessment

Calculation of neutron fluence to dose equivalent conversion coefficients using GEANT4

International Nuclear Information System (INIS)

Ribeiro, Rosane M.; Santos, Denison de S.; Queiroz Filho, Pedro P. de; Mauricio, CLaudia L.P.; Silva, Livia K. da; Pessanha, Paula R.

2014-01-01

Fluence to dose equivalent conversion coefficients provide the basis for the calculation of area and personal monitors. Recently, the ICRP has started a revision of these coefficients, including new Monte Carlo codes for benchmarking. So far, little information is available about neutron transport below 10 MeV in tissue-equivalent (TE) material performed with Monte Carlo GEANT4 code. The objective of this work is to calculate neutron fluence to personal dose equivalent conversion coefficients, H p (10)/Φ, with GEANT4 code. The incidence of monoenergetic neutrons was simulated as an expanded and aligned field, with energies ranging between thermal neutrons to 10 MeV on the ICRU slab of dimension 30 x 30 x 15 cm 3 , composed of 76.2% of oxygen, 10.1% of hydrogen, 11.1% of carbon and 2.6% of nitrogen. For all incident energy, a cylindrical sensitive volume is placed at a depth of 10 mm, in the largest surface of the slab (30 x 30 cm 2 ). Physic process are included for neutrons, photons and charged particles, and calculations are made for neutrons and secondary particles which reach the sensitive volume. Results obtained are thus compared with values published in ICRP 74. Neutron fluence in the sensitive volume was calculated for benchmarking. The Monte Carlo GEANT4 code was found to be appropriate to calculate neutron doses at energies below 10 MeV correctly. (author)

A combination of differential method and perturbation theory for the calculation of sensitivity coefficients

International Nuclear Information System (INIS)

Santos, Adimir dos; Borges, A.A.

2000-01-01

A new method for the calculation of sensitivity coefficients is developed. The new method is a combination of two methodologies used for calculating these coefficients, which are the differential and the generalized perturbation theory methods. The proposed method utilizes as integral parameter the average flux in an arbitrary region of the system. Thus, the sensitivity coefficient contains only the component corresponding to the neutron flux. To obtain the new sensitivity coefficient, the derivates of the integral parameter, φ(ξ), with respect to σ are calculated using the perturbation method and the functional derivates of this generic integral parameter with respect to σ and φ are calculated using the differential method. The new method merges the advantages of the differential and generalized perturbation theory methods and eliminates their disadvantages. (author)

A simple theory of linear mode conversion

International Nuclear Information System (INIS)

Cairns, R.A.; Lashmore-Davies, C.N.; Woods, A.M.

1984-01-01

A summary is given of the basic theory of linear mode conversion involving the construction of differential equations for the mode amplitudes based on the properties of the dispersion relation in the neighbourhood of the mode conversion point. As an example the transmission coefficient for tunneling from the upper hybrid resonance through the evanescent region to the adjacent cut-off is treated. 7 refs, 3 figs

Stationarity-conservation laws for fractional differential equations with variable coefficients

International Nuclear Information System (INIS)

Klimek, Malgorzata

2002-01-01

In this paper, we study linear fractional differential equations with variable coefficients. It is shown that, by assuming some conditions for the coefficients, the stationarity-conservation laws can be derived. The area where these are valid is restricted by the asymptotic properties of solutions of the respective equation. Applications of the proposed procedure include the fractional Fokker-Planck equation in (1+1)- and (d+1)-dimensional space and the fractional Klein-Kramers equation. (author)

Stationarity-conservation laws for fractional differential equations with variable coefficients

Energy Technology Data Exchange (ETDEWEB)

Klimek, Malgorzata [Institute of Mathematics and Computer Science, Technical University of Czestochowa, Czestochowa (Poland)

2002-08-09

In this paper, we study linear fractional differential equations with variable coefficients. It is shown that, by assuming some conditions for the coefficients, the stationarity-conservation laws can be derived. The area where these are valid is restricted by the asymptotic properties of solutions of the respective equation. Applications of the proposed procedure include the fractional Fokker-Planck equation in (1+1)- and (d+1)-dimensional space and the fractional Klein-Kramers equation. (author)

ESTIMATION OF THE CONVERSION COEFFICIENTS FROM DOSE-AREA PRODUCT TO EFFECTIVE DOSE FOR BARIUM MEAL EXAMINATIONS FOR ADULT PATIENTS

Directory of Open Access Journals (Sweden)

A. V. Vodovatov

2018-01-01

Full Text Available Fluoroscopic examinations of the upper gastro-intestinal tract and, especially, barium meal examinations, are commonly performed in a majority of hospitals. These examinations are associated both with substantial individual patient doses and contribution to the collective dose from medical exposure. Effective dose estimation for this type of examinations is complicated due to: 1 the necessity to simulate the moving X-ray irradiation field; 2 differences in study structure for the individual patients; 3 subjectivity of the operators; and 4 differences in the X-ray equipment. The aim of the current study was to estimate conversion coefficients from dose-area product to effective dose for barium meal examinations for the over couch and under couch exposure conditions. The study was based on data collected in the X-ray unit of the surgical department of the St-Petersburg Mariinsky hospital. A model of patient exposure during barium meal examination was developed based on the collected data on fluoroscopy protocols and adult patient irradiation geometry. Conversion coefficients were calculated using PCXMC 2.0 software. Complete examinations were converted into a set of typical fluoroscopy phases and X-ray images, specified by the examined anatomical region and the projection of patient exposure. Conversion coefficients from dose-area product to effective dose were calculated for each phase of the examination and for the complete examination. The resulting values of the conversion coefficients are comparable with published data. Variations in the absolute values of the conversion coefficients can be explained by differences in clinical protocols, models for the estimation of the effective dose and parameters of barium meal examinations. The proposed approach for estimation of effective dose considers such important features of fluoroscopic examinations as: 1 non-uniform structure of examination, 2 significant movement of the X-ray tube within a single

A combination between the differential and the perturbation theory methods for calculating sensitivity coefficients

International Nuclear Information System (INIS)

Borges, Antonio Andrade

1998-01-01

A new method for the calculation of sensitivity coefficients is developed. The new method is a combination of two methodologies used for calculating theses coefficients, which are the differential and the generalized perturbation theory methods. The method utilizes as integral parameter the average flux in an arbitrary region of the system. Thus, the sensitivity coefficient contains only the component corresponding to the neutron flux. To obtain the new sensitivity coefficient, the derivatives of the integral parameter, Φ, with respect to σ are calculated using the perturbation method and the functional derivatives of this generic integral parameter with respect to σ and Φ are calculated using the differential method. (author)

Determination of average conversion coefficients between kerma in air and H⁎(10) using primary and secondary X-ray beams and transmitted in the diagnostic radiology energy range

International Nuclear Information System (INIS)

Santos, Josilene C.; Gonzalez, Alejandro H.L.; Costa, Paulo R.

2016-01-01

Brazilian regulation establishes 1.14 Sv/Gy as unique conversion coefficient to convert air-kerma into the operational quantity ambient dose equivalent H⁎(10) disregarding its beam quality dependence. The present study computed mean conversion coefficients from primary, secondary and transmitted X-ray beams through barite mortar plates used in shielding of dedicated chest radiographic facilities in order to improve the current assessment of H⁎(10). To compute the mean conversion coefficients, the weighting of conversion coefficients corresponding to monoenergetic beams with the spectrum energy distribution in terms of air-kerma was considered. The maximum difference between the obtained conversion coefficients and the constant value recommended in national regulation is 53.4%. The conclusion based on these results is that a constant coefficient is not adequate for deriving the H⁎(10) from air-kerma measurements. (author)

Applicability of dose conversion coefficients of ICRP 74 to Asian adult males: Monte Carlo simulation study

International Nuclear Information System (INIS)

Lee, Choonsik; Lee, Choonik; Lee, Jai-Ki

2007-01-01

International Commission on Radiological Protection (ICRP) reported comprehensive dose conversion coefficients for adult population, which is exposed to external photon sources in the Publication 74. However, those quantities were calculated from so-called stylized (or mathematical) phantoms composed of simplified mathematical surface equations so that the discrepancy between the phantoms and real human anatomy has been investigated by several authors using Caucasian-based voxel phantoms. To address anatomical and racial limitations of the stylized phantoms, several Asian-based voxel phantoms have been developed by Korean and Japanese investigators, independently. In the current study, photon dose conversion coefficients of ICRP 74 were compared with those from a total of five Asian-based male voxel phantoms, whose body dimensions were almost identical. Those of representative radio-sensitive organs (testes, red bone marrow, colon, lungs, and stomach), and effective dose conversion coefficients were obtained for comparison. Even though organ doses for testes, colon and lungs, and effective doses from ICRP 74 agreed well with those from Asian voxel phantoms within 10%, absorbed doses for red bone marrow and stomach showed significant discrepancies up to 30% which was mainly attributed to difference of phantom description between stylized and voxel phantoms. This study showed that the ICRP 74 dosimetry data, which have been reported to be unrealistic compared to those from Caucasian-based voxel phantoms, are also not appropriate for Asian population

Calculation of age-dependent dose conversion coefficients for radionuclides uniformly distributed in air

International Nuclear Information System (INIS)

Hung, Tran Van; Satoh, Daiki; Takahashi, Fumiaki; Tsuda, Shuichi; Endo, Akira; Saito, Kimiaki; Yamaguchi, Yasuhiro

2005-02-01

Age-dependent dose conversion coefficients for external exposure to photons emitted by radionuclides uniformly distributed in air were calculated. The size of the source region in the calculation was assumed to be effectively semi-infinite in extent. Firstly, organ doses were calculated with a series of age-specific MIRD-5 type phantoms using MCNP code, a Monte Carlo transport code. The calculations were performed for mono-energetic photon sources of twelve energies from 10 keV to 5 MeV and for phantoms of newborn, 1, 5, 10 and 15 years, and adult. Then, the effective doses to the different age-phantoms from the mono-energetic photon sources were estimated based on the obtained organ doses. The calculated effective doses were used to interpolate the conversion coefficients of the effective doses for 160 radionuclides, which are important for dose assessment of nuclear facilities. In the calculation, energies and intensities of emitted photons from radionuclides were taken from DECDC, a recent compilation of decay data for radiation dosimetry developed at JAERI. The results are tabulated in the form of effective dose per unit concentration and time (Sv per Bq s m -3 ). (author)

OSCILLATION FOR NEUTRAL DELAY DIFFERENTIAL EQUATION WITH POSITIVE AND NEGATIVE COEFFICIENTS

Institute of Scientific and Technical Information of China (English)

无

2006-01-01

In this paper, a new oscillating result is established for the first order neutral delay differential equation with positive and negative coefficients, which improves and generalizes several results in the literatures.

Internal conversion coefficients for atomic numbers Z less than or equal to 30

International Nuclear Information System (INIS)

Band, I.M.; Trzhaskovskaya, M.B.; Listengarten, M.A.

1976-01-01

Presented here are internal conversion coefficients (ICC) of gamma rays for 20 values of atomic number, Z, in the range 3 less than or equal to Z less than or equal to 30, including all Z greater than or equal to 14. The tables provide the previously missing data for light elements. Coefficients are given for 19 values of gamma-ray transition energies up to 6 MeV for the K-electron shell and 18 values up to 2 MeV for three L-subshells. The minimum enegy is 15 keV. The first five electric and magnetic nuclear transition multipolarities are covered. The calculations are relativistic, with screening and finite nuclear size effect taken into account

Measurement of conversion coefficients between air Kerma and personal dose equivalent and backscatter factors for diagnostic X-ray beams

International Nuclear Information System (INIS)

Rosado, Paulo Henrique Goncalves

2008-01-01

Two sets of quantities are import in radiological protection: the protection and operational quantities. Both sets can be related to basic physical quantities such as kerma through conversion coefficients. For diagnostic x-ray beams the conversion coefficients and backscatter factors have not been determined yet, those parameters are need for calibrating dosimeters that will be used to determine the personal dose equivalent or the entrance skin dose. Conversion coefficients between air kerma and personal dose equivalent and backscatter factors were experimentally determined for the diagnostic x-ray qualities RQR and RQA recommended by the International Electrotechnical Commission (IEC). The air kerma in the phantom and the mean energy of the spectrum were measured for such purpose. Harshaw LiF-100H thermoluminescent dosemeters (TLD) were used for measurements after being calibrated against an 180 cm 3 Radcal Corporation ionization chamber traceable to a reference laboratory. A 300 mm x 300 mm x 150 mm polymethylmethacrylate (PMMA) slab phantom was used for deep-dose measurements. Tl dosemeters were placed in the central axis of the x-ray beam at 5, 10, 15, 25 and 35 mm depth in the phantom upstream the beam direction Another required parameter for determining the conversion coefficients from was the mean energy of the x-ray spectrum. The spectroscopy of x-ray beams was done with a CdTe semiconductor detector that was calibrated with 133 Ba, 241 Am and 57 Co radiation sources. Measurements of the x-ray spectra were carried out for all RQR and RQA IEC qualities. Corrections due to the detector intrinsic efficiency, total energy absorption, escape fraction of the characteristic x-rays, Compton effect and attenuation in the detector were done aiming an the accurate determination of the mean energy. Measured x-ray spectra were corrected with the stripping method by using these response functions. The typical combined standard uncertainties of conversion coefficients and

Determination of the conversion coefficient for ambient dose equivalent, H(10), from air kerma measurements

International Nuclear Information System (INIS)

Gonzalez J, F.; Alvarez R, J. T.

2015-09-01

Namely the operational magnitudes can be determined by the product of a conversion coefficient by exposure air kerma or fluence, etc. In particular in Mexico for the first time is determined the conversion coefficient (Cc) for operational magnitude Environmental Dose Equivalent H(10) by thermoluminescence dosimetry (TLD) technique. First 30 TLD-100 dosimeters are calibrated in terms of air kerma, then these dosimeters are irradiated inside a sphere ICRU type of PMMA and with the aid of theory cavity the absorbed dose in PMMA is determined at a depth of 10 mm within the sphere D PMMA (10), subsequently absorbed dose to ICRU tissue is corrected and the dose equivalent H(10) is determined. The Cc is determined as the ratio of H(10)/K a obtaining a value of 1.20 Sv Gy -1 with a u c = 3.66%, this being consistent with the published value in ISO-4037-3 of 1.20 Sv Gy -1 with a u c = 2%. (Author)

Coupling between the differential and perturbation theory methods for calculating sensitivity coefficients in nuclear transmutation problems

International Nuclear Information System (INIS)

Rossi, Lubianka Ferrari Russo

2014-01-01

The main target of this study is to introduce a new method for calculating the coefficients of sensibility through the union of differential method and generalized perturbation theory, which are the two methods generally used in reactor physics to obtain such variables. These two methods, separated, have some issues turning the sensibility coefficients calculation slower or computationally exhaustive. However, putting them together, it is possible to repair these issues and build a new equation for the coefficient of sensibility. The method introduced in this study was applied in a PWR reactor, where it was performed the sensibility analysis for the production and 239 Pu conversion rate during 120 days (1 cycle) of burnup. The computational code used for both burnup and sensibility analysis, the CINEW, was developed in this study and all the results were compared with codes widely used in reactor physics, such as CINDER and SERPENT. The new mathematical method for calculating the sensibility coefficients and the code CINEW provide good numerical agility and also good efficiency and security, once the new method, when compared with traditional ones, provide satisfactory results, even when the other methods use different mathematical approaches. The burnup analysis, performed using the code CINEW, was compared with the code CINDER, showing an acceptable variation, though CINDER presents some computational issues due to the period it was built. The originality of this study is the application of such method in problems involving temporal dependence and, not least, the elaboration of the first national code for burnup and sensitivity analysis. (author)

Transformation formulas for legendre coefficients of double-differential cross sections

International Nuclear Information System (INIS)

Shi Xiangjun; Zhang Jingshang

1989-01-01

Approximate analytical formulas have been derived for the transformation of Legendre coefficients of double-differential continuum cross sections of two-body nuclear reactions from the center-of-mass to the laboratory system. This transformation differs from that of elastic-scattering angular distribution coefficients on its accuracy which depends not only upon the target mass, but also upon outgoing energies. A fast code has been written to transform Legendre coefficients of neutron inelastic scattering cross-sections. The calculations have been carried out using a recently introduced numerical integration method for more complicated problems in which the energy spectrum is either an evaporation spectrum or a spectrum obtained from a (pre-)compound model. The results are quite satisfactory provided that the target mass or the outgoing energy is not sufficiently low

Converting Sabine absorption coefficients to random incidence absorption coefficients

DEFF Research Database (Denmark)

Jeong, Cheol-Ho

2013-01-01

are suggested: An optimization method for the surface impedances for locally reacting absorbers, the flow resistivity for extendedly reacting absorbers, and the flow resistance for fabrics. With four porous type absorbers, the conversion methods are validated. For absorbers backed by a rigid wall, the surface...... coefficients to random incidence absorption coefficients are proposed. The overestimations of the Sabine absorption coefficient are investigated theoretically based on Miki's model for porous absorbers backed by a rigid wall or an air cavity, resulting in conversion factors. Additionally, three optimizations...... impedance optimization produces the best results, while the flow resistivity optimization also yields reasonable results. The flow resistivity and flow resistance optimization for extendedly reacting absorbers are also found to be successful. However, the theoretical conversion factors based on Miki's model...

EXISTENCE AND UNIQUENESS OF SOLUTIONS TO STOCHASTIC DIFFERENTIAL EQUATION WITH RANDOM COEFFICIENTS

Institute of Scientific and Technical Information of China (English)

无

2010-01-01

This paper mainly deals with a stochastic differential equation (SDE) with random coefficients. Sufficient conditions which guarantee the existence and uniqueness of solutions to the equation are given.

Observation of changing of the internal conversion coefficient under Moessbauer effect at magnetic transition in Rh-Fe system

International Nuclear Information System (INIS)

Ruskov, T.

1998-01-01

The magnetic disorder-order transition in the Rh-Fe alloy is studied by conversion electron Moessbauer spectroscopy. The drastic increase of the area under the Moessbauer spectrum at the transition from the paramagnetic to the magnetic state could be explained by diminishing the internal conversion coefficient. Thus our experimental results directly confirm the theory of the collective effect in the system of radiating developed by Yukalov

Infinite time interval backward stochastic differential equations with continuous coefficients.

Science.gov (United States)

Zong, Zhaojun; Hu, Feng

2016-01-01

In this paper, we study the existence theorem for [Formula: see text] [Formula: see text] solutions to a class of 1-dimensional infinite time interval backward stochastic differential equations (BSDEs) under the conditions that the coefficients are continuous and have linear growths. We also obtain the existence of a minimal solution. Furthermore, we study the existence and uniqueness theorem for [Formula: see text] [Formula: see text] solutions of infinite time interval BSDEs with non-uniformly Lipschitz coefficients. It should be pointed out that the assumptions of this result is weaker than that of Theorem 3.1 in Zong (Turkish J Math 37:704-718, 2013).

Conversion of time-varying Stokes coefficients into mass anomalies at the Earth's surface considering the Earth's oblateness

Science.gov (United States)

Ditmar, Pavel

2018-02-01

Time-varying Stokes coefficients estimated from GRACE satellite data are routinely converted into mass anomalies at the Earth's surface with the expression proposed for that purpose by Wahr et al. (J Geophys Res 103(B12):30,205-30,229, 1998). However, the results obtained with it represent mass transport at the spherical surface of 6378 km radius. We show that the accuracy of such conversion may be insufficient, especially if the target area is located in a polar region and the signal-to-noise ratio is high. For instance, the peak values of mean linear trends in 2003-2015 estimated over Greenland and Amundsen Sea embayment of West Antarctica may be underestimated in this way by about 15%. As a solution, we propose an updated expression for the conversion of Stokes coefficients into mass anomalies. This expression is based on the assumptions that: (i) mass transport takes place at the reference ellipsoid and (ii) at each point of interest, the ellipsoidal surface is approximated by the sphere with a radius equal to the current radial distance from the Earth's center ("locally spherical approximation"). The updated expression is nearly as simple as the traditionally used one but reduces the inaccuracies of the conversion procedure by an order of magnitude. In addition, we remind the reader that the conversion expressions are defined in spherical (geocentric) coordinates. We demonstrate that the difference between mass anomalies computed in spherical and ellipsoidal (geodetic) coordinates may not be negligible, so that a conversion of geodetic colatitudes into geocentric ones should not be omitted.

Sabine absorption coefficients to random incidence absorption coefficients

DEFF Research Database (Denmark)

Jeong, Cheol-Ho

2014-01-01

into random incidence absorption coefficients for porous absorbers are investigated. Two optimization-based conversion methods are suggested: the surface impedance estimation for locally reacting absorbers and the flow resistivity estimation for extendedly reacting absorbers. The suggested conversion methods...

Partial differential equations II elements of the modern theory equations with constant coefficients

CERN Document Server

Shubin, M

1994-01-01

This book, the first printing of which was published as Volume 31 of the Encyclopaedia of Mathematical Sciences, contains a survey of the modern theory of general linear partial differential equations and a detailed review of equations with constant coefficients. Readers will be interested in an introduction to microlocal analysis and its applications including singular integral operators, pseudodifferential operators, Fourier integral operators and wavefronts, a survey of the most important results about the mixed problem for hyperbolic equations, a review of asymptotic methods including short wave asymptotics, the Maslov canonical operator and spectral asymptotics, a detailed description of the applications of distribution theory to partial differential equations with constant coefficients including numerous interesting special topics.

Measurement of K-conversion coefficient of the M3 transition in sup 112 In sup m

Energy Technology Data Exchange (ETDEWEB)

Krishna, K.R.; Sastry, D.L.; Reddy, K.V. (Andhra Univ., Visakhapatnam (India). Labs. for Nuclear Research); Chintalapudi, S.N. (Variable Energy Cyclotron Centre, Calcutta (India))

1991-11-01

The K-conversion coefficient of the 155 keV (M3) isomeric transition in the decay of {sup 112}In was measured using the normalized peak to gamma method. The {alpha}{sub K} value is found to be 4.82{+-}0.29 in agreement with the theoretical value of 5.12. (author).

Conversational assessment in memory clinic encounters: interactional profiling for differentiating dementia from functional memory disorders.

Science.gov (United States)

Jones, Danielle; Drew, Paul; Elsey, Christopher; Blackburn, Daniel; Wakefield, Sarah; Harkness, Kirsty; Reuber, Markus

2016-01-01

In the UK dementia is under-diagnosed, there is limited access to specialist memory clinics, and many of the patients referred to such clinics are ultimately found to have functional (non-progressive) memory disorders (FMD), rather than a neurodegenerative disorder. Government initiatives on 'timely diagnosis' aim to improve the rate and quality of diagnosis for those with dementia. This study seeks to improve the screening and diagnostic process by analysing communication between clinicians and patients during initial specialist clinic visits. Establishing differential conversational profiles could help the timely differential diagnosis of memory complaints. This study is based on video- and audio recordings of 25 initial consultations between neurologists and patients referred to a UK memory clinic. Conversation analysis was used to explore recurrent communicative practices associated with each diagnostic group. Two discrete conversational profiles began to emerge, to help differentiate between patients with dementia and functional memory complaints, based on (1) whether the patient is able to answer questions about personal information; (2) whether they can display working memory in interaction; (3) whether they are able to respond to compound questions; (4) the time taken to respond to questions; and (5) the level of detail they offer when providing an account of their memory failure experiences. The distinctive conversational profiles observed in patients with functional memory complaints on the one hand and neurodegenerative memory conditions on the other suggest that conversational profiling can support the differential diagnosis of functional and neurodegenerative memory disorders.

Third-order operator-differential equations with discontinuous coefficients and operators in the boundary conditions

Directory of Open Access Journals (Sweden)

Araz R. Aliev

2013-10-01

Full Text Available We study a third-order operator-differential equation on the semi-axis with a discontinuous coefficient and boundary conditions which include an abstract linear operator. Sufficient conditions for the well-posed and unique solvability are found by means of properties of the operator coefficients in a Sobolev-type space.

Study of the coefficients of internal conversion for transition energies approaching the threshold

International Nuclear Information System (INIS)

Farani Coursol, Nelcy.

1979-01-01

Internal conversion coefficients were determined experimentally with great accuracy for areas of transition energies, which constitute tests for the theories (energies at the most ten kEv above the threshold of K shell), then the results obtained were compared with the values calculated (or to be calculated) from theoretical models. Owing to the difficulties raised by the precise determination of the internal conversion coefficients (ICC), in the first stage we selected radionuclides with a relatively simple decay pattern, the transitions: 30 keV of sup(93m)Nb, 35 keV of sup(125m)Te, 14 keV of 57 Fe and 39 keV of sup(129m)Xe. It was observed that 'problems' exist with respect to the ICC's of the great multipolarity transitions, so the transitions of this kind were examined in a systematic manner. The possibility of penetration effects occurring for the transitions studied experimentally was examined. The considerations are presented which 'authorized' us to disregard the dynamic part of the ICC for the transitions approaching the threshold (L selection rules and life of nuclear levels in relation to Weisskopf-Moszkowski estimations). The Kurie straight line was determined experimentally for the β - transition and the Qsub(β) was evaluated with an important accuracy gain compared with the values available at present. Finally, a certain number of ICC's of transitions already determined with good precision were recalculated, in order to extend our analysis and detect any possible systematic errors [fr

Calculation of conversion coefficients using Chinese adult reference phantoms for air submersion and ground contamination.

Science.gov (United States)

Lu, Wei; Qiu, Rui; Wu, Zhen; Li, Chunyan; Yang, Bo; Liu, Huan; Ren, Li; Li, Junli

2017-03-21

The effective and organ equivalent dose coefficients have been widely used to provide assessment of doses received by adult members of the public and by workers exposed to environmental radiation from nuclear facilities under normal or accidental situations. Advancements in phantom types, weighting factors, decay data, etc, have led to the publication of newer results in this regard. This paper presents a new set of conversion coefficients for air submersion and ground contamination (with the use of Geant4) for photons from 15 keV to 10 MeV using the Chinese and International Commission on Radiological Protection (ICRP) adult reference male and female phantoms. The radiation fields, except for energy spectrum at low energies, were validated by the data obtained from the Monte Carlo code YURI. The effective dose coefficients of monoenergetic photons, obtained for the ICRP adult reference phantoms, agree well with recently published data for air submersion and ground contamination with a plane source at a depth of 0.5 g cm -2 in soil, but an average difference of 36.5% is observed for ground surface contamination with the abovementioned radiation field. The average differences in organ equivalent dose coefficients between the Chinese and the ICRP adult reference phantoms are within 6% for most organs, but noticeable differences of up to 70% or even higher are found at photon energies below 30 keV under air submersion. The effective dose coefficients obtained with the Chinese adult reference phantoms are greater than those of the ICRP adult reference phantoms above 30 keV and 0.5 MeV for ground contamination and air submersion, respectively; the average differences from the Chinese adult reference phantoms are about 3.6% and 0.4% in the whole energy range with maximum differences of 31.8% and 27.6% at 15 keV for air submersion and ground contamination respectively. These differences are attributed to anatomical discrepancies in overlying tissue mass of an

Successive approximation analog to digital conversion system with good differential linearity

Energy Technology Data Exchange (ETDEWEB)

Carter, D E; Randers-Pehrson, G [Ohio Univ., Athens (USA). Dept. of Physics

1982-08-15

A high speed modified successive approximation 4 input ADC system has been designed and constructed. Throughput rates of 250 kHz at 12 bit conversion gain with good differential linearity is achieved at low cost, using the MPX4 ADC system.

Standardization and determination of the total internal conversion coefficient of In-111.

Science.gov (United States)

Matos, Izabela T; Koskinas, Marina F; Nascimento, Tatiane S; Yamazaki, Ione M; Dias, Mauro S

2014-05-01

The standardization of (111)In by means of a 4πβ-γ coincidence system, composed of a proportional counter in 4π geometry, coupled to a 20% relative efficiency HPGe crystal, for measuring gamma-rays is presented. The data acquisition was performed by means of the software coincidence system (SCS) and the activity was determined by the extrapolation technique. Two gamma-ray windows were selected: at 171 keV and 245 keV total absorption peaks, allowing the determination of the total internal conversion coefficient for these two gamma transitions. The results were compared with those available in the literature. © 2013 Published by Elsevier Ltd.

Oscillation Criteria of First Order Neutral Delay Differential Equations with Variable Coefficients

Directory of Open Access Journals (Sweden)

Fatima N. Ahmed

2013-01-01

Full Text Available Some new oscillation criteria are given for first order neutral delay differential equations with variable coefficients. Our results generalize and extend some of the well-known results in the literature. Some examples are considered to illustrate the main results.

Linear Ordinary Differential Equations with Constant Coefficients. Revisiting the Impulsive Response Method Using Factorization

Science.gov (United States)

Camporesi, Roberto

2011-01-01

We present an approach to the impulsive response method for solving linear constant-coefficient ordinary differential equations based on the factorization of the differential operator. The approach is elementary, we only assume a basic knowledge of calculus and linear algebra. In particular, we avoid the use of distribution theory, as well as of…

Dose conversion coefficients for monoenergetic electrons incident on a realistic human eye model with different lens cell populations.

Science.gov (United States)

Nogueira, P; Zankl, M; Schlattl, H; Vaz, P

2011-11-07

The radiation-induced posterior subcapsular cataract has long been generally accepted to be a deterministic effect that does not occur at doses below a threshold of at least 2 Gy. Recent epidemiological studies indicate that the threshold for cataract induction may be much lower or that there may be no threshold at all. A thorough study of this subject requires more accurate dose estimates for the eye lens than those available in ICRP Publication 74. Eye lens absorbed dose per unit fluence conversion coefficients for electron irradiation were calculated using a geometrical model of the eye that takes into account different cell populations of the lens epithelium, together with the MCNPX Monte Carlo radiation transport code package. For the cell population most sensitive to ionizing radiation-the germinative cells-absorbed dose per unit fluence conversion coefficients were determined that are up to a factor of 4.8 higher than the mean eye lens absorbed dose conversion coefficients for electron energies below 2 MeV. Comparison of the results with previously published values for a slightly different eye model showed generally good agreement for all electron energies. Finally, the influence of individual anatomical variability was quantified by positioning the lens at various depths below the cornea. A depth difference of 2 mm between the shallowest and the deepest location of the germinative zone can lead to a difference between the resulting absorbed doses of up to nearly a factor of 5000 for electron energy of 0.7 MeV.

Dose conversion coefficients for monoenergetic electrons incident on a realistic human eye model with different lens cell populations

International Nuclear Information System (INIS)

Nogueira, P; Vaz, P; Zankl, M; Schlattl, H

2011-01-01

The radiation-induced posterior subcapsular cataract has long been generally accepted to be a deterministic effect that does not occur at doses below a threshold of at least 2 Gy. Recent epidemiological studies indicate that the threshold for cataract induction may be much lower or that there may be no threshold at all. A thorough study of this subject requires more accurate dose estimates for the eye lens than those available in ICRP Publication 74. Eye lens absorbed dose per unit fluence conversion coefficients for electron irradiation were calculated using a geometrical model of the eye that takes into account different cell populations of the lens epithelium, together with the MCNPX Monte Carlo radiation transport code package. For the cell population most sensitive to ionizing radiation-the germinative cells-absorbed dose per unit fluence conversion coefficients were determined that are up to a factor of 4.8 higher than the mean eye lens absorbed dose conversion coefficients for electron energies below 2 MeV. Comparison of the results with previously published values for a slightly different eye model showed generally good agreement for all electron energies. Finally, the influence of individual anatomical variability was quantified by positioning the lens at various depths below the cornea. A depth difference of 2 mm between the shallowest and the deepest location of the germinative zone can lead to a difference between the resulting absorbed doses of up to nearly a factor of 5000 for electron energy of 0.7 MeV.

Nonlinear perturbations of systems of partial differential equations with constant coefficients

Directory of Open Access Journals (Sweden)

Carmen J. Vanegas

2000-01-01

Full Text Available In this article, we show the existence of solutions to boundary-value problems, consisting of nonlinear systems of partial differential equations with constant coefficients. For this purpose, we use the right inverse of an associated operator and a fix point argument. As illustrations, we apply this method to Helmholtz equations and to second order systems of elliptic equations.

Oscillation Criteria in First Order Neutral Delay Impulsive Differential Equations with Constant Coefficients

International Nuclear Information System (INIS)

Dimitrova, M. B.; Donev, V. I.

2008-01-01

This paper is dealing with the oscillatory properties of first order neutral delay impulsive differential equations and corresponding to them inequalities with constant coefficients. The established sufficient conditions ensure the oscillation of every solution of this type of equations.

Age-specific effective doses for pediatric MSCT examinations at a large children's hospital using DLP conversion coefficients: a simple estimation method

International Nuclear Information System (INIS)

Thomas, Karen E.; Wang, Bo

2008-01-01

There is a need for an easily accessible method for effective dose estimation in pediatric CT. To estimate effective doses for a variety of pediatric neurological and body CT examinations in five age groups using recently published age- and region-specific dose length product (DLP) to effective dose conversion coefficients. A retrospective review was performed of 1,431 consecutive CT scans over a 12-week period using age- and weight-adjusted CT protocols. Age- and region-specific DLP to effective dose conversion coefficients were applied to console-displayed DLP data. Effective dose estimates for single-phase head CT scans in neonatal, and 1-, 5-, 10- and 15-year-old age groups were 4.2, 3.6, 2.4, 2.0 and 1.4 mSv, respectively. For abdomen/pelvis CT scans the corresponding effective doses were 13.1, 11.1, 8.4, 8.9 and 5.9 mSv. The range of pediatric CT effective doses is wide, from ultralow dose protocols (<1 mSv) to extended-coverage body examinations (10-15 mSv). Age- and region-specific pediatric DLP to effective dose conversion coefficients provide an accessible and user-friendly method for estimating pediatric CT effective doses that is available to radiologists working without medical physics support. (orig.)

Comparing Hp(3) evaluated from the conversion coefficients from air kerma to personal dose equivalent for eye lens dosimetry calibrated on a new cylindrical PMMA phantom

Science.gov (United States)

Esor, J.; Sudchai, W.; Monthonwattana, S.; Pungkun, V.; Intang, A.

2017-06-01

Based on a new occupational dose limit recommended by ICRP (2011), the annual dose limit for the lens of the eye for workers should be reduced from 150 mSv/y to 20 mSv/y averaged over 5 consecutive years in which no single year exceeding 50 mSv. This new dose limit directly affects radiologists and cardiologists whose work involves high radiation exposure over 20 mSv/y. Eye lens dosimetry (Hp(3)) has become increasingly important and should be evaluated directly based on dosimeters that are worn closely to the eye. Normally, Hp(3) dose algorithm was carried out by the combination of Hp(0.07) and Hp(10) values while dosimeters were calibrated on slab PMMA phantom. Recently, there were three reports from European Union that have shown the conversion coefficients from air kerma to Hp(3). These conversion coefficients carried out by ORAMED, PTB and CEA Saclay projects were performed by using a new cylindrical head phantom. In this study, various delivered doses were calculated using those three conversion coefficients while nanoDot, small OSL dosimeters, were used for Hp(3) measurement. These calibrations were performed with a standard X-ray generator at Secondary Standard Dosimetry Laboratory (SSDL). Delivered doses (Hp(3)) using those three conversion coefficients were compared with Hp(3) from nanoDot measurements. The results showed that percentage differences between delivered doses evaluated from the conversion coefficient of each project and Hp(3) doses evaluated from the nanoDots were found to be not exceeding -11.48 %, -8.85 % and -8.85 % for ORAMED, PTB and CEA Saclay project, respectively.

Terahertz-wave differential detection based on simultaneous dual-wavelength up-conversion

Directory of Open Access Journals (Sweden)

Yuma Takida

2017-03-01

Full Text Available We report a terahertz (THz-wave differential detection based on simultaneous dual-wavelength up-conversion in a nonlinear optical MgO:LiNbO3 crystal with optical and electronic THz-wave sources. The broadband parametric gain and noncollinear phase-matching of MgO:LiNbO3 provide efficient conversion from superposed THz waves to spatially distributed near-infrared (NIR beams to function as a dispersive THz-wave spectrometer without any additional dispersive element. We show that the μW-level THz waves from two independent sources, a 0.78-THz injection-seeded THz-wave parametric generator (is-TPG and a 1.14-THz resonant tunneling diode (RTD, are simultaneously up-converted to two NIR waves and then detected with two NIR photodetectors. By applying a balanced detection scheme to this dual-frequency detection, we demonstrate THz-wave differential imaging of maltose and polyethylene pellets in the transmission geometry. This dual-wavelength detection is applicable to more than three frequencies and broadband THz-wave radiation for real-time THz-wave spectroscopic detection and imaging.

Estimation of saturation activities for activation experiments in CHARM and CSBF using Fluence Conversion Coefficients

CERN Document Server

Guerin, Helene Chloe; Iliopoulou, Elpida; CERN. Geneva. HSE Department

2017-01-01

As summer student at CERN, I have been working in the Radiation Protection group for 10 weeks. I worked with the \\textsc{Fluka} Monte Carlo simulation code, using Fluence Conversion Coefficients method to perform simulations to estimate the saturation activities for activation experiments in the \\textsc{CSBF} and the \\textsc{Charm} facility in the East Experimental Area. The provided results will be used to plan a Monte Carlo benchmark in the \\textsc{CSBF} during a beam period at the end of August 2017.

Modulating Functions Based Algorithm for the Estimation of the Coefficients and Differentiation Order for a Space-Fractional Advection-Dispersion Equation

KAUST Repository

Aldoghaither, Abeer

2015-12-01

In this paper, a new method, based on the so-called modulating functions, is proposed to estimate average velocity, dispersion coefficient, and differentiation order in a space-fractional advection-dispersion equation, where the average velocity and the dispersion coefficient are space-varying. First, the average velocity and the dispersion coefficient are estimated by applying the modulating functions method, where the problem is transformed into a linear system of algebraic equations. Then, the modulating functions method combined with a Newton\\'s iteration algorithm is applied to estimate the coefficients and the differentiation order simultaneously. The local convergence of the proposed method is proved. Numerical results are presented with noisy measurements to show the effectiveness and robustness of the proposed method. It is worth mentioning that this method can be extended to general fractional partial differential equations.

Modulating Functions Based Algorithm for the Estimation of the Coefficients and Differentiation Order for a Space-Fractional Advection-Dispersion Equation

KAUST Repository

Aldoghaither, Abeer; Liu, Da-Yan; Laleg-Kirati, Taous-Meriem

2015-01-01

In this paper, a new method, based on the so-called modulating functions, is proposed to estimate average velocity, dispersion coefficient, and differentiation order in a space-fractional advection-dispersion equation, where the average velocity and the dispersion coefficient are space-varying. First, the average velocity and the dispersion coefficient are estimated by applying the modulating functions method, where the problem is transformed into a linear system of algebraic equations. Then, the modulating functions method combined with a Newton's iteration algorithm is applied to estimate the coefficients and the differentiation order simultaneously. The local convergence of the proposed method is proved. Numerical results are presented with noisy measurements to show the effectiveness and robustness of the proposed method. It is worth mentioning that this method can be extended to general fractional partial differential equations.

A fresh look at linear ordinary differential equations with constant coefficients. Revisiting the impulsive response method using factorization

Science.gov (United States)

Camporesi, Roberto

2016-01-01

We present an approach to the impulsive response method for solving linear constant-coefficient ordinary differential equations of any order based on the factorization of the differential operator. The approach is elementary, we only assume a basic knowledge of calculus and linear algebra. In particular, we avoid the use of distribution theory, as well as of the other more advanced approaches: Laplace transform, linear systems, the general theory of linear equations with variable coefficients and variation of parameters. The approach presented here can be used in a first course on differential equations for science and engineering majors.

Analysis and Improvement of Adaptive Coefficient Third Harmonic Voltage Differential Stator Grounding Protection

Directory of Open Access Journals (Sweden)

Ying Zhu

2018-06-01

Full Text Available This paper presents a novel third harmonic voltage differential stator grounding protection (THV-DSGP method combining the adaptive coefficient and fixed coefficient. It can solve the protection sensitivity degradation problem when the insulation resistance of stator winding to ground is slowly declining. This protection method retains the advantages of the adaptive coefficient, which is to maintain high sensitivity in case of an instantaneous ground fault. Moreover, the fixed coefficient can remember the initial insulation state of the stator winding and prevent relay failure when the stator insulation is slowly declining. In addition, due to zero-sequence voltage disconnection (ZSVD often leading to malfunctioning of the THV stator ground protection, the existing criterion of the ZSVD was improved according to the electrical characteristics of the generator when ZSVD happens. THV-DSGP with both adaptive coefficient and fixed coefficient was simulated in the Matlab/Simulink. The simulation results show that the proposed protection can be applied to the slow ground fault of the stator winding. Furthermore, the improved criterion of ZSVD can effectively distinguish the stator metal earth fault and the secondary loop break of the zero-sequence voltage.

Fluence to absorbed foetal dose conversion coefficients for photons in 50 keV-10 GeV calculated using RPI-P models

International Nuclear Information System (INIS)

Taranenko, V.; Xu, X.G.

2008-01-01

Radiation protection of pregnant females and the foetus against ionising radiation is of particular importance to radiation protection due to high foetal radiosensitivity. The only available set of foetal conversion coefficients for photons is based on stylised models of simplified anatomy. Using the RPI-P series of pregnant female and foetus models representing 3-, 6- and 9-month gestation, a set of new fluence to absorbed foetal dose conversion coefficients has been calculated. The RPI-P anatomical models were developed using novel 3D geometry modelling techniques. Organ masses were adjusted to agree within 1% with the ICRP reference data for a pregnant female. Monte Carlo dose calculations were carried out using the MCNPX and Penelope codes for external 50 keV-10 GeV photon beams of six standard configurations. The models were voxelised at 3-mm voxel resolution. Conversion coefficients were tabulated for the three gestational periods for the whole foetus and brain. Comparison with previously published data showed deviations up to 120% for the foetal doses at 50 keV. The discrepancy can be primarily ascribed to anatomical differences. Comparison with published data for five major mother organs is also provided for the 3-month model. Since the RPI-P models exhibit a high degree of anatomical realism, the reported dataset is recommended as a reference for radiation protection of the foetus against external photon exposure. (authors)

[Dissociation (conversion) - malingering - antisocial personality disorder: differential diagnostic reflection on the basis of a case study].

Science.gov (United States)

Rothuber, Helfried; Mitterauer, Bernhard

2011-01-01

In this case report we refer to the big challenge of making a diagnosis in a deliberate malingering in the field of mental disorders. We specifically describe the difficulty regarding the differentiation between a conversion disorder and malingering of a serial delinquent. For such a person avoiding criminal persecution is one of the most frequent reason to deceitfully simulate a mental illness. In this field, symptoms of conversion disorders exceed the average; furthermore, a great number of organic-neurological illnesses may appear to be very similar to a conversion disorder or in many cases a neurological disorder can actually be detected in the course of a somatic examination. A further obstacle for the differential diagnosis can be seen in the difficulty to discern it from factitious disorders. However, it is quite possible to discern the deliberate malingering of a mental disorder from a conversion disorder by means of the diligent diagnosis of a competent and experienced doctor/assessor who specialises.

Dose conversion coefficients for neutron exposure to the lens of the human eye

International Nuclear Information System (INIS)

Manger, Ryan P.; Bellamy, Michael B.; Eckerman, Keith F.

2011-01-01

Dose conversion coefficients for the lens of the human eye have been calculated for neutron exposure at energies from 1 x 10 -9 to 20 MeV and several standard orientations: anterior-to-posterior, rotational and right lateral. MCNPX version 2.6.0, a Monte Carlo-based particle transport package, was used to determine the energy deposited in the lens of the eye. The human eyeball model was updated by partitioning the lens into sensitive and insensitive volumes as the anterior portion (sensitive volume) of the lens being more radiosensitive and prone to cataract formation. The updated eye model was used with the adult UF-ORNL mathematical phantom in the MCNPX transport calculations.

Dose conversion coefficients for neutron exposure to the lens of the human eye

International Nuclear Information System (INIS)

Manger, R. P.; Bellamy, M. B.; Eckerman, K. F.

2012-01-01

Dose conversion coefficients for the lens of the human eye have been calculated for neutron exposure at energies from 1 x 10 -9 to 20 MeV and several standard orientations: anterior-to-posterior, rotational and right lateral. MCNPX version 2.6.0, a Monte Carlo-based particle transport package, was used to determine the energy deposited in the lens of the eye. The human eyeball model was updated by partitioning the lens into sensitive and insensitive volumes as the anterior portion (sensitive volume) of the lens being more radiosensitive and prone to cataract formation. The updated eye model was used with the adult UF-ORNL mathematical phantom in the MCNPX transport calculations. (authors)

Stochastic differential equtions with non-lipschitz coefficients:II. Dependence with respect to initial values

OpenAIRE

Fang, Shizan; Zhang, Tusheng

2003-01-01

14 pages; The existence of the unique strong solution for a class of stochastic differential equations with non-Lipschitz coefficients was established recently. In this paper, we shall investigate the dependence with respect to the initial values. We shall prove that the non confluence of solutions holds under our general conditions. To obtain a continuous version, the modulus of continuity of coefficients is assumed to be less than $\\dis |x-y|\\log{1\\over|x-y|}$. In this case, it will give ri...

A study on the stem friction coefficient with differential pressure conditions for the motor operated flexible wedge gate valve

International Nuclear Information System (INIS)

Kim, Dae Woong; Park, Sung Keun; Kim, Yang Seok; Lee, Do Hwan

2008-01-01

Stem friction coefficient is very important parameter for the evaluation of valve performance. In this study, the characteristics of stem friction coefficient is analyzed, and the bounding value is determined. The hydraulic testing is performed for flexible wedge gate valves in the plant and statistical method is applied to the determination of bounding value. According to the results of this study, stem friction coefficient is not effected in low differential pressure condition, but it is showed different distribution in medium and high differential pressure condition. And the bounding value of closing stroke is higher than that of opening stroke

Effective dose conversion coefficients for X-ray radiographs of the chest and the abdomen

Energy Technology Data Exchange (ETDEWEB)

Lima, F.R.A. [Centro regional de Ciencias Nucleares, CRCN/CNEN, Rua Conego Barata, 999, Tamarineira, Recife, PE (Brazil); Kramer, R.; Vieira, J.W.; Khoury, H.J. [Departamento de Energia Nuclear, DEN/UFPE, Cidade Universitaria, Recife, PE (Brazil)]. E-mail: falima@cnen.gov.br

2004-07-01

The recently developed MAX (Male Adult voXel) and the FAXht (Female Adult voXel) head and trunk phantoms have been used to calculate organ and tissue equivalent dose conversion coefficients for X-ray radiographs of the chest and the abdomen as a function of source and field parameters, like voltage, filtration, field size, focus-to-skin distance, etc. Based on the equivalent doses to twenty three organs and tissues at risk, the effective dose has been determined and compared with corresponding data for others phantoms. The influence of different radiation transport codes, different tissue compositions and different human anatomies have been investigated separately. (Author)

Effective dose conversion coefficients for X-ray radiographs of the chest and the abdomen

International Nuclear Information System (INIS)

Lima, F.R.A.; Kramer, R.; Vieira, J.W.; Khoury, H.J.

2004-01-01

The recently developed MAX (Male Adult voXel) and the FAXht (Female Adult voXel) head and trunk phantoms have been used to calculate organ and tissue equivalent dose conversion coefficients for X-ray radiographs of the chest and the abdomen as a function of source and field parameters, like voltage, filtration, field size, focus-to-skin distance, etc. Based on the equivalent doses to twenty three organs and tissues at risk, the effective dose has been determined and compared with corresponding data for others phantoms. The influence of different radiation transport codes, different tissue compositions and different human anatomies have been investigated separately. (Author)

Total conversion coefficient of the 185 keV (10--7+) transition in sup(182m)Ta

International Nuclear Information System (INIS)

Suryanarayana, Ch.; Venkateswara Rao, N.; Raghavaiah, C.V.; Bhuloka Reddy, S.; Satyanarayana, G.; Sastry, D.L.

1988-01-01

The total conversion coefficient of the 185 keV (E3) isomeric transition in 182 Ta was measured for the first time using gamma intensity balance method. The experimental αsub(T) was obtained as 3.4 ± 0.2 consistent with the theoretical value (3.272) due to Rosel et al. The E3 transition probability was found to be hindered by a factor of 5.07x10 4 when compared to the single particle estimate. (author). 13 refs

Radon progeny dose conversion coefficients for Chinese males and females

Energy Technology Data Exchange (ETDEWEB)

Yu, K.N. E-mail: peter.yu@city.edu.hk; Cheung, T.T.K.; Haque, A.K.M.M.; Nikezic, D.; Lau, B.M.F.; Vucic, D

2001-07-01

The airway dimensions for Caucasian males have been scaled by multiplying by factors 0.95 and 0.88 to give those for Chinese males and females, respectively. Employing the most recent data on physical and biological parameters, the radiation doses to the basal and secretory cells due to {alpha} particles from {sup 218}Po and {sup 214}Po, homogeneously distributed in the mucous layer, have been calculated. The emission of {alpha} particles has been simulated by a Monte Carlo method. For both basal and secretory cells, the dose conversion coefficients (DCCs) for physical conditions of sleep, rest, light and heavy exercise, have been obtained for Chinese males and females for unattached progeny, and for attached progeny of diameters 0.02, 0.15, 0.25, 0.30 and 0.50 {mu}m. For basal cells, the coefficients lie in the range 0.69-6.82 mGy/(J s/m{sup 3}) or 8.7-86 mGy/WLM for unattached progeny and in the range 0.045-1.98 mGy/(J s/m{sup 3}) or 0.57-25 mGy/WLM for attached progeny. The corresponding ranges for Caucasian males are 1.27-8.81 mGy/(J s/m{sup 3}) or 16-111 mGy/WLM{sup -1} and 0.05-2.30 mGy/(J s/m{sup 3}) or 0.64-29 mGy/WLM. For secretory cells, the coefficients lie in the range 0.095-16.82 mGy/(J s/m{sup 3}) (1.2-212 mGy/WLM) for unattached progeny and in the range 0.095-6.67 mGy/(J s/m{sup 3}) (1.2-84 mGy/WLM) for attached progeny. The corresponding ranges for Caucasian males are 0.34-21.51 mGy/(J s/m{sup 3}) (4.3-271 mGy/WLM) and 0.1-7.78 mGy/(J s/m{sup 3}) (1.3-98 mGy/WLM). The overall DCCs calculated for a typical home environment are 0.59 and 0.52 mSv/(J s/m{sup 3}) (7.4 and 6.5 mSv/WLM) for Chinese males and females, respectively, which are 80 and 70% of the value, 0.73 mSv/(J s/m{sup 3}) (9.2 mSv/WLM), for Caucasian males.

Differentiability of Palmer's linearization Theorem and converse result for density functions

OpenAIRE

Castañeda, Alvaro; Robledo, Gonzalo

2014-01-01

We study differentiability properties in a particular case of the Palmer's linearization Theorem, which states the existence of an homeomorphism $H$ between the solutions of a linear ODE system having exponential dichotomy and a quasilinear system. Indeed, if the linear system is uniformly asymptotically stable, sufficient conditions ensuring that $H$ is a $C^{2}$ preserving orientation diffeomorphism are given. As an application, we generalize a converse result of density functions for a non...

Lie symmetries of systems of second-order linear ordinary differential equations with constant coefficients.

Science.gov (United States)

Boyko, Vyacheslav M; Popovych, Roman O; Shapoval, Nataliya M

2013-01-01

Lie symmetries of systems of second-order linear ordinary differential equations with constant coefficients are exhaustively described over both the complex and real fields. The exact lower and upper bounds for the dimensions of the maximal Lie invariance algebras possessed by such systems are obtained using an effective algebraic approach.

Pure E2 transitions: A test for BRICC Internal Conversion Coefficients

International Nuclear Information System (INIS)

Gerl, J.; Sai, K. Vijay; Sainath, M.; Gowrishankar, R.; Venkataramaniah, K.

2009-01-01

The most widely used theoretical internal conversion coefficient (ICC) tables are of Hager and Seltzer (HS), Rosel et al. and BRICC (Band et al. tables using BRICC interpolation code). A rigorous comparison of experimental ICCs with various theoretical tabulations is possible only when a large data on experimental ICCs is available at one place. For this reason, a compilation of all the available experimental ICCs, α T , α K , α L of E2 transitions for a number of elements in the range of 24≤Z≤94 is presented. Listing of experimental data includes 595 datasets corresponding to 505 E2 transitions in 165 nuclei across the nuclear chart. Data with less than 10% experimental uncertainty have been selected for comparison with the theoretical values of Hager and Seltzer, Rosel et al. and BRICC. The relative percentage deviation (%Δ) have been calculated for each of the above theories and the average (%Δ) are estimated. The Band et al. tables, using the BRICC interpolation code are seen to give theoretical ICCs closest to experimental values.

Body talk among undergraduate women: why conversations about exercise and weight loss differentially predict body appreciation.

Science.gov (United States)

Wasylkiw, Louise; Butler, Nicole A

2014-08-01

Undergraduate women (N = 143) completed self-reports on exercise behavior, body orientation, body appreciation, and body-related talk. Results showed that conversations about weight loss/dieting and conversations about exercise differentially predicted body appreciation. Importantly, multiple regression analyses showed that the relationship between talk type and body appreciation was explained by the object-process dichotomy: Conversations about exercise oriented women to consider what their bodies can do which, in turn, predicted appreciation of one's body. In contrast, the relationship between conversations about weight loss/dieting and body appreciation was mediated by negative attitudes about one's body but not by an object orientation. © The Author(s) 2013.

Method for internal conversion coefficients determination by means of a magnetic spectrometer. Application to 129Xe and 77Se

International Nuclear Information System (INIS)

Arqueros, F.; Campos, J.

1986-01-01

The method used for efficiency calibration of a magnetic electron spectrometer and its applications to conversion electron spectrometry is described. The present results point out that apparatus combining magnetic deflection and semiconductor detection have a nondecreasing interest in nuclear spectrometry for applications where good resolution and large background rejection are both necessary. The present apparatus can be employed with source of relatively low activity, (0.lμCi). The nuclides studied were 129 Xe and 77 Se resulting from 129 Cs and 77 Br decay. The parent nulcides were produced in ISOLDE on line isotope separator at CERN. The efficiency calibration method used for energies higher than 200 keV made use of the well known beta spectrum of 36 Cl. The calibration for low energies was made with Auger electron intensities and suitable conversion lines of 129 Xenon. Results for relative intensities of conversion electron lines and intense gamma lines of 129 Xe and 77 Se are given. From these measurements internal conversion coefficients for transitions of both nuclides were obtained. The results were in agreement with theoretical calculations. (author)

Internal conversion coefficients of high multipole transitions: Experiment and theories

International Nuclear Information System (INIS)

Gerl, J.; Vijay Sai, K.; Sainath, M.; Gowrishankar, R.; Venkataramaniah, K.

2008-01-01

A compilation of the available experimental internal conversion coefficients (ICCs), α T , α K , α L , and ratios K/L and K/LM of high multipole (L > 2) transitions for a number of elements in the range 21 ≤ Z ≤ 94 is presented. Our listing of experimental data includes 194 data sets on 110 E3 transitions, 10 data sets on 6 E4 transitions, 11 data sets on 7 E5 transitions, 38 data sets on 21 M3 transitions, and 132 data sets on 68 M4 transitions. Data with less than 10% experimental uncertainty have been selected for comparison with the theoretical values of Hager and Seltzer [R.S. Hager, E.C. Seltzer, Nucl. Data Tables A 4 (1968) 1], Rosel et al. [F. Roesel, H.M. Fries, K. Alder, H.C. Pauli, At. Data Nucl. Data Tables 21 (1978) 91], and BRICC. The relative percentage deviations (%Δ) have been calculated for each of the above theories and the averages (%Δ-bar) are estimated. The Band et al. [I.M. Band, M.B. Trzhaskovskaya, C.W. Nestor Jr., P.O. Tikkanen, S. Raman, At. Data Nucl. Data Tables 81 (2002) 1] tables, using the BRICC interpolation code, are seen to give theoretical ICCs closest to experimental values

Existence of positive solutions for multi-term non-autonomous fractional differential equations with polynomial coefficients

Directory of Open Access Journals (Sweden)

Azizollah Babakhani

2006-10-01

Full Text Available In the present paper we discuss the existence of positive solutions in the case of multi-term non-autonomous fractional differential equations with polynomial coefficients; the constant coefficient case has been studied in [2]. We consider the equation $$ Big(D^{alpha_n} -sum_{j = 1}^{n - 1} p_j(xD^{alpha_{n - j}}Bigy = f(x, y. $$ We state various conditions on $f$ and $p_j$'s under which this equation has: positive solutions, a unique solution which is positive, and a unique solution which may not be positive.

A Fresh Look at Linear Ordinary Differential Equations with Constant Coefficients. Revisiting the Impulsive Response Method Using Factorization

Science.gov (United States)

Camporesi, Roberto

2016-01-01

We present an approach to the impulsive response method for solving linear constant-coefficient ordinary differential equations of any order based on the factorization of the differential operator. The approach is elementary, we only assume a basic knowledge of calculus and linear algebra. In particular, we avoid the use of distribution theory, as…

Fluence-to-effective dose conversion coefficients from a Saudi population based phantom for monoenergetic photon beams from 10 keV to 20 MeV

International Nuclear Information System (INIS)

Ma, Andy K; Hussein, Mohammed Adel; Altaher, Khalid Mohammed; Farid, Khalid Yousif; Amer, Mamun; Aldhafery, Bander Fuhaid; Alghamdi, Ali A

2015-01-01

Fluence-to-dose conversion coefficients are important quantities for radiation protection, derived from Monte Carlo simulations of the radiation particles through a stylised phantom or voxel based phantoms. The voxel phantoms have been developed for many ethnic groups for their accurate reflection of the anatomy. In this study, we used the Monte Carlo code MCNPX to calculate the photon fluence-to-effective dose conversion coefficients with a voxel phantom based on the Saudi Arabian male population. Six irradiation geometries, anterior–posterior (AP), posterior–anterior (PA), left lateral (LLAT), right lateral (RLAT), rotational (ROT) and isotropic (ISO) were simulated for monoenergetic photon beams from 10 keV to 20 MeV. We compared the coefficients with the reference values in ICRP Publication 116. The coefficients in the AP and PA geometries match the reference values to 9% and 12% on average as measured by root mean square while those in the LLAT, RLAT ROT and ISO geometries differ, mostly below, from the reference by 23, 22, 15 and 16%, respectively. The torso of the Saudi phantom is wider than the ICRP reference male phantom and likely to cause more attenuation to the lateral beam. The ICRP reference coefficients serve well for the Saudi male population as conservative estimations for the purpose of radiation protection. (paper)

Numerical approximations of stochastic differential equations with non-globally Lipschitz continuous coefficients

CERN Document Server

Hutzenthaler, Martin

2015-01-01

Many stochastic differential equations (SDEs) in the literature have a superlinearly growing nonlinearity in their drift or diffusion coefficient. Unfortunately, moments of the computationally efficient Euler-Maruyama approximation method diverge for these SDEs in finite time. This article develops a general theory based on rare events for studying integrability properties such as moment bounds for discrete-time stochastic processes. Using this approach, the authors establish moment bounds for fully and partially drift-implicit Euler methods and for a class of new explicit approximation method

On k-summability of formal solutions for certain partial differential operators with polynomial coefficients

Directory of Open Access Journals (Sweden)

Kunio Ichinobe

2015-01-01

Full Text Available We study the \\(k\\-summability of divergent formal solutions for the Cauchy problem of certain linear partial differential operators with coefficients which are polynomial in \\(t\\. We employ the method of successive approximation in order to construct the formal solutions and to obtain the properties of analytic continuation of the solutions of convolution equations and their exponential growth estimates.

Reproducibility of The Random Incidence Absorption Coefficient Converted From the Sabine Absorption Coefficient

DEFF Research Database (Denmark)

Jeong, Cheol-Ho; Chang, Ji-ho

2015-01-01

largely depending on the test room. Several conversion methods for porous absorbers from the Sabine absorption coefficient to the random incidence absorption coefficient were suggested by considering the finite size of a test specimen and non-uniformly incident energy onto the specimen, which turned out...... resistivity optimization outperforms the surface impedance optimization in terms of the reproducibility....

Calculation of conversion coefficients of dose of a computational anthropomorphic simulator sit exposed to a plane source

International Nuclear Information System (INIS)

Santos, William S.; Carvalho Junior, Alberico B. de; Pereira, Ariana J.S.; Santos, Marcos S.; Maia, Ana F.

2011-01-01

In this paper conversion coefficients (CCs) of equivalent dose and effective in terms of kerma in the air were calculated suggested by the ICRP 74. These dose coefficients were calculated considering a plane radiation source and monoenergetic for a spectrum of energy varying from 10 keV to 2 MeV. The CCs were obtained for four geometries of irradiation, anterior-posterior, posterior-anterior, lateral right side and lateral left side. It was used the radiation transport code Visual Monte Carlo (VMC), and a anthropomorphic simulator of sit female voxel. The observed differences in the found values for the CCs at the four irradiation sceneries are direct results of the body organs disposition, and the distance of these organs to the irradiation source. The obtained CCs will be used for estimative more precise of dose in situations that the exposed individual be sit, as the normally the CCs available in the literature were calculated by using simulators always lying or on their feet

Performance of Differential-Phase-Shift Keying Protocol Applying 1310 nm Up-Conversion Single-Photon Detector

International Nuclear Information System (INIS)

Chen-Xu, Feng; Rong-Zhen, Jiao; Wen-Han, Zhang

2008-01-01

The performance of the differential-phase-shift keying (DPSK) protocol applying a 1310 nm up-conversion single-photon detector is analysed. The error rate and the communication rate as a function of distance for three quantum key distribution protocols, the Bennett–Brassard 1984, the Bennett–Brassard–Mermin 1992, and the DPSK, are presented. Then we compare the performance of these three protocols using the 1310nm up-conversion detector. We draw the conclusion that the DPSK protocol applying the detector has significant advantage over the other two protocols. Longer transmission distance and lower error rate can be achieved. (general)

On the discrete spectrum of non-self-adjoint Schroedinger differential equation with an operator coefficient

International Nuclear Information System (INIS)

Bayramoglu, Mehmet; Tasci, Fatih; Zeynalov, Djafar

2004-01-01

We study the discrete part of spectrum of a singular non-self-adjoint second-order differential equation on a semiaxis with an operator coefficient. Its boundedness is proved. The result is applied to the Schroedinger boundary value problem -Δu+q(x)u=λ 2 u, u vertical bar ∂D =0, with a complex potential q(x) in an angular domain

Measurement of conversion coefficients in 208Tl

International Nuclear Information System (INIS)

Wendling, F.

1976-06-01

A electron spectrometer composed by a Li drifted Si detector and a uniform magnetic field was constructed. The magnetic field is used to focus the electrons on the detector and to filter the other radiations. After the construction the instrument was calibrated in absolute eficience and was used together with a Ge(Li) spectrometer also calibrated, in the measurement of internal conversion coeficients of the 433 and 453 keV transitions in 208 Tl [pt

Proton and photon absorbed-dose conversion coefficients for embryo and foetus from top-down irradiation geometry

International Nuclear Information System (INIS)

Chen, J.

2007-01-01

Absorbed-dose conversion coefficients are calculated for the embryo of 8 weeks and the foetus of 3, 6 or 9 months when the mother's body is exposed to protons and photons from top-down (TOP) direction. It provides data sets in addition to other standard irradiation geometries published previously. The TOP-irradiation geometry is considered here, because high-energy particles are often peaked from the TOP direction onboard aircraft. The results show that absorbed-doses from high-energy particles could be underestimated significantly if isotropic (ISO) irradiation geometry is assumed. For protons of 100 GeV, absorbed-doses from TOP irradiation are ∼2.3-2.9 times higher than the doses from ISO irradiation for different foetal ages. For 10 GeV photons, foetal doses from TOP irradiation are ∼6.8-12 times higher than the doses from ISO irradiation. The coefficients from TOP-irradiation geometry are given in wide energy ranges, from 100 MeV to 100 GeV for protons and from 50 V to 10 GeV for photons. They can, therefore, be used in various applications whenever exposure from the TOP-irradiation direction is concerned. (authors)

On a numerical method for solving integro-differential equations with variable coefficients with applications in finance

Science.gov (United States)

Kudryavtsev, O.; Rodochenko, V.

2018-03-01

We propose a new general numerical method aimed to solve integro-differential equations with variable coefficients. The problem under consideration arises in finance where in the context of pricing barrier options in a wide class of stochastic volatility models with jumps. To handle the effect of the correlation between the price and the variance, we use a suitable substitution for processes. Then we construct a Markov-chain approximation for the variation process on small time intervals and apply a maturity randomization technique. The result is a system of boundary problems for integro-differential equations with constant coefficients on the line in each vertex of the chain. We solve the arising problems using a numerical Wiener-Hopf factorization method. The approximate formulae for the factors are efficiently implemented by means of the Fast Fourier Transform. Finally, we use a recurrent procedure that moves backwards in time on the variance tree. We demonstrate the convergence of the method using Monte-Carlo simulations and compare our results with the results obtained by the Wiener-Hopf method with closed-form expressions of the factors.

Fluence-to-Absorbed Dose Conversion Coefficients for Use in Radiological Protection of Embryo and Foetus Against External Exposure to Muons from 20MeV to 50GeV

International Nuclear Information System (INIS)

Chen Jing

2008-01-01

This study used the Monte-Carlo code MCNPX to determine mean absorbed doses to the embryo and foetus when the mother is exposed to external muon fields. Monoenergetic muons ranging from 20 MeV to 50 GeV were considered. The irradiation geometries include anteroposterior (AP), postero-anterior (PA), lateral (LAT), rotational (ROT), isotropic (ISO), and top-down (TOP). At each of these irradiation geometries, absorbed doses to the foetal body were calculated for the embryo of 8 weeks and the foetus of 3, 6 or 9 months, respectively. Muon fluence-to-absorbed-dose conversion coefficients were derived for the four prenatal ages. Since such conversion coefficients are yet unknown, the results presented here fill a data gap

The local skin dose conversion coefficients of electrons, protons and alpha particles calculated using the Geant4 code.

Science.gov (United States)

Zhang, Bintuan; Dang, Bingrong; Wang, Zhuanzi; Wei, Wei; Li, Wenjian

2013-10-01

The skin tissue-equivalent slab reported in the International Commission on Radiological Protection (ICRP) Publication 116 to calculate the localised skin dose conversion coefficients (LSDCCs) was adopted into the Monte Carlo transport code Geant4. The Geant4 code was then utilised for computation of LSDCCs due to a circular parallel beam of monoenergetic electrons, protons and alpha particles electrons and alpha particles are found to be in good agreement with the results using the MCNPX code of ICRP 116 data. The present work thus validates the LSDCC values for both electrons and alpha particles using the Geant4 code.

Assessment of histological differentiation in gastric cancers using whole-volume histogram analysis of apparent diffusion coefficient maps.

Science.gov (United States)

Zhang, Yujuan; Chen, Jun; Liu, Song; Shi, Hua; Guan, Wenxian; Ji, Changfeng; Guo, Tingting; Zheng, Huanhuan; Guan, Yue; Ge, Yun; He, Jian; Zhou, Zhengyang; Yang, Xiaofeng; Liu, Tian

2017-02-01

To investigate the efficacy of histogram analysis of the entire tumor volume in apparent diffusion coefficient (ADC) maps for differentiating between histological grades in gastric cancer. Seventy-eight patients with gastric cancer were enrolled in a retrospective 3.0T magnetic resonance imaging (MRI) study. ADC maps were obtained at two different b values (0 and 1000 sec/mm 2 ) for each patient. Tumors were delineated on each slice of the ADC maps, and a histogram for the entire tumor volume was subsequently generated. A series of histogram parameters (eg, skew and kurtosis) were calculated and correlated with the histological grade of the surgical specimen. The diagnostic performance of each parameter for distinguishing poorly from moderately well-differentiated gastric cancers was assessed by using the area under the receiver operating characteristic curve (AUC). There were significant differences in the 5 th , 10 th , 25 th , and 50 th percentiles, skew, and kurtosis between poorly and well-differentiated gastric cancers (P histogram parameters, including the 10 th percentile, skew, kurtosis, and max frequency; the correlation coefficients were 0.273, -0.361, -0.339, and -0.370, respectively. Among all the histogram parameters, the max frequency had the largest AUC value, which was 0.675. Histogram analysis of the ADC maps on the basis of the entire tumor volume can be useful in differentiating between histological grades for gastric cancer. 4 J. Magn. Reson. Imaging 2017;45:440-449. © 2016 International Society for Magnetic Resonance in Medicine.

Measurement of secondary cosmic radiation and calculation of associated dose conversion coefficients for humans

International Nuclear Information System (INIS)

Simmer, Gregor

2012-01-01

Due to secondary cosmic radiation (SCR), pilots and flight attendants receive elevated effective doses at flight altitudes. For this reason, since 2003 aircrew members are considered as occupationally exposed, in Germany. This work deals with the calculation of dose conversion coefficients (DCC) for protons, neutrons, electrons, positrons, photons and myons, which are crucial for estimation of effective dose from SCR. For the first time, calculations were performed combining Geant4 - a Monte Carlo code developed at CERN - with the voxel phantoms for the reference female and male published in 2008 by ICRP and ICRU. Furthermore, measurements of neutron fluence spectra - which contribute the major part to the effective dose of SCR - were carried out at the Environmental Research Station Schneefernerhaus (UFS) located at 2650 m above sea level nearby the Zugspitze mountain, Germany. These measured neutron spectra, and additionally available calculated spectra, were then folded with the DCC calculated in this work, and effective dose rates for different heights were calculated.

Determination of the conversion coefficient for ambient dose equivalent, H(10), from air kerma measurements; Determinacion del coeficiente de conversion para la dosis equivalente ambiental, H*(10), a partir de mediciones de kerma en aire

Energy Technology Data Exchange (ETDEWEB)

Gonzalez J, F. [UNAM, Facultad de Ciencias, Circuito Exterior, Ciudad Universitaria, 04510 Ciudad de Mexico (Mexico); Alvarez R, J. T., E-mail: trinidad.alvarez@inin.gob.mx [ININ, Departamento de Metrologia de Radiaciones Ionizantes, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico)

2015-09-15

Namely the operational magnitudes can be determined by the product of a conversion coefficient by exposure air kerma or fluence, etc. In particular in Mexico for the first time is determined the conversion coefficient (Cc) for operational magnitude Environmental Dose Equivalent H(10) by thermoluminescence dosimetry (TLD) technique. First 30 TLD-100 dosimeters are calibrated in terms of air kerma, then these dosimeters are irradiated inside a sphere ICRU type of PMMA and with the aid of theory cavity the absorbed dose in PMMA is determined at a depth of 10 mm within the sphere D{sub PMMA}(10), subsequently absorbed dose to ICRU tissue is corrected and the dose equivalent H(10) is determined. The Cc is determined as the ratio of H(10)/K{sub a} obtaining a value of 1.20 Sv Gy{sup -1} with a u{sub c}= 3.66%, this being consistent with the published value in ISO-4037-3 of 1.20 Sv Gy{sup -1} with a u{sub c}= 2%. (Author)

Fluence-to-absorbed dose conversion coefficients for use in radiological protection of embryo and foetus against external exposure to protons from 100 MeV to 100 GeV

International Nuclear Information System (INIS)

Chen, J.

2006-01-01

In the literature, no conversion coefficients are available for use in radiological protection of embryo and foetus against external exposure to protons. This study used the Monte Carlo code MCNPX to determine mean absorbed doses to the embryo and foetus when the mother is exposed to proton fields. Monoenergetic protons ranging from 100 MeV to 100 GeV were considered. The irradiation geometries include antero-posterior (AP), postero-anterior (PA), lateral (LAT), rotational (ROT) and isotropic (ISO). At each of these standard irradiation geometries, absorbed doses to the foetal brain and body were calculated for the embryo of 8 weeks and the foetus of 3, 6 or 9 months. Proton fluence-to-absorbed dose conversion coefficients were derived for the four prenatal ages. (authors)

Four-body conversion of atomic helium ions

International Nuclear Information System (INIS)

de Vries, C.P.; Oskam, H.J.

1980-01-01

The conversion of atomic helium ions into molecular ions was studied in pure helium and in helium-neon mixtures containing between 0.1 at. % and 50 at. % neon. The experiments showed that the termolecular conversion reaction, He + +2He → He 2 + +He, is augmented by the four-body conversion reaction He + +3He → products, where the products could include either He 2 + or He 3 + ions. Conversion rate coefficients of (5.7 +- 0.8) x 10 -32 cm 6 sec -1 and (2.6 +- 0.4) x 10 -49 cm 9 sec -1 were found for the termolecular and four-body conversion reactions, respectively. In addition, rate coefficients for the following Ne + conversion reactions were measured: Ne + +He+He → (HeNe) + +He, (2.3 +- 0.1) x 10 -32 cm 6 sec -1 ; Ne + +He+Ne → (HeNe) + +Ne or Ne 2 + +He, (8.0 +- 0.8) x 10 -32 cm 6 sec -1 ; and Ne + +Ne+Ne → Ne 2 + +Ne, (5.1 +- 0.3) x 10 -32 cm 6 sec -1 . All rate coefficients are at a gas temperature of 295 K

Internal conversion coefficients of M4 isomeric transitions in /sup 125/ /sup 127/ /sup 129/Te decay

Energy Technology Data Exchange (ETDEWEB)

Soni, S K; Kumar, A; Gupta, S L; Pancholi, S C [Delhi Univ. (India). Dept. of Physics and Astrophysics

1977-01-01

The internal conversion coefficients have been measured using a high resolution low energy Ge(Li) detector for the following M4 transitions: /sup 125/Te: 109.27 keV transition ..cap alpha..sub(T) = 357 +- 11; RG method, /sup 127/Te: 88,26 keV transition ..cap alpha..sub(K) = 484 +- 23; XPG method, /sup 129/Te: 105.50 keV transition ..cap alpha..sub(K) = 213 +- 10; XPG method. It is observed that these values are lower by 2.5-3.6% as compared with Hager and Seltzer's calculations. A comparison between experimental and theoretical ..cap alpha..sub(K) and ..cap alpha..sub(T) values for eleven M4 transitions shows that the experimental values are systematically lower.

Approximate Solutions of Delay Differential Equations with Constant and Variable Coefficients by the Enhanced Multistage Homotopy Perturbation Method

Directory of Open Access Journals (Sweden)

D. Olvera

2015-01-01

Full Text Available We expand the application of the enhanced multistage homotopy perturbation method (EMHPM to solve delay differential equations (DDEs with constant and variable coefficients. This EMHPM is based on a sequence of subintervals that provide approximate solutions that require less CPU time than those computed from the dde23 MATLAB numerical integration algorithm solutions. To address the accuracy of our proposed approach, we examine the solutions of several DDEs having constant and variable coefficients, finding predictions with a good match relative to the corresponding numerical integration solutions.

Implementing Families of Implicit Chebyshev Methods with Exact Coefficients for the Numerical Integration of First- and Second-Order Differential Equations

National Research Council Canada - National Science Library

Mitchell, Jason

2002-01-01

A method is presented for the generation of exact numerical coefficients found in two families of implicit Chebyshev methods for the numerical integration of first- and second-order ordinary differential equations...

Fractional approximations for linear first order differential equation with polynomial coefficients-application to E1(x) and Z(s)

International Nuclear Information System (INIS)

Martin, P.; Zamudio-Cristi, J.

1982-01-01

A method is described to obtain fractional approximations for linear first order differential equations with polynomial coefficients. This approximation can give good accuracy in a large region of the complex variable plane that may include all the real axis. The parameters of the approximation are solutions of algebraic equations obtained through the coefficients of the highest and lowest power of the variable after the sustitution of the fractional approximation in the differential equation. The method is more general than the asymptotical Pade method, and it is not required to determine the power series or asymptotical expansion. A simple approximation for the exponential integral is found, which give three exact digits for most of the real values of the variable. Approximations of higher accuracy and of the same degree than other authors are also obtained. (Author) [pt

Determination of the absolute K through O conversion coefficients of the 80-keV M4 transition in /sup 193/Ir/sup m/

International Nuclear Information System (INIS)

Lindner, M.; Gunnink, R.; Nagle, R.J.

1987-01-01

We produced carrier-free, nearly isotopically pure /sup 193/Ir/sup m/ from thermal-neutron irradiation of /sup 192/Os. From studies of the conversion-electron spectrum, the photon spectrum, and the absolute counting rates, we determined the absolute K, L1, L2, L3, M1, M3, M5, N, and O+P conversion coefficients for the first time. With possibly one exception, these values agree closely with theoretical calculations. The value for the energy of the unconverted gamma ray was found to be 80.22 +- 0.02 keV. The half-life for /sup 193/Ir/sup m/ determined by absolute electron counting in a proportional counter of 100% counting efficiency (4πβ) was found to be 10.53 +- 0.04 d. We have determined the L 1 subshell fluorescence yield, ω 1 , to be 0.120 +- 0.003 for iridium. Based upon our measurements of initial and final L subshell vacancies together with a best-fit literature value for ω 2 , we have found a plausible value for the Coster-Kronig coefficient f/sub 12/ to be 0.091 +- 0.011

Estimated fluence-to-absorbed dose conversion coefficients for use in radiological protection of embryo and foetus against external exposure to photons from 50 keV to 10 GeV

International Nuclear Information System (INIS)

Chen, J.

2006-01-01

In the literature, no conversion coefficients are available for use in radiological protection of the embryo and foetus against external exposure to photons. This study used the Monte-Carlo code MCNPX to determine mean absorbed doses to the embryo and foetus when the mother is exposed to external photon fields. Monoenergetic photons ranging from 50 keV to 10 GeV were considered. The irradiation geometries included antero-posterior (AP), postero-anterior (PA), lateral (LAT), rotational (ROT), and isotropic (ISO). At each of these standard irradiation geometries, absorbed doses to the foetal brain and body were calculated for the embryo of 8 weeks and the foetus of 3, 6 or 9 months. Photon fluence-to-absorbed-dose conversion coefficients were estimated for the four prenatal ages. (authors)

Calculation of conversion coefficients Hp(3)/K air using the PENELOPE Monte Carlo code and comparison with MCNP calculation results

International Nuclear Information System (INIS)

Daures, J.; Gouriou, J.; Bordy, J.M.

2010-01-01

The authors report calculations performed using the MNCP and PENELOPE codes to determine the Hp(3)/K air conversion coefficient which allows the Hp(3) dose equivalent to be determined from the measured value of the kerma in the air. They report the definition of the phantom, a 20 cm diameter and 20 cm high cylinder which is considered as representative of a head. Calculations are performed for an energy range corresponding to interventional radiology or cardiology (20 keV-110 keV). Results obtained with both codes are compared

Validity of the CT to attenuation coefficient map conversion methods

International Nuclear Information System (INIS)

Faghihi, R.; Ahangari Shahdehi, R.; Fazilat Moadeli, M.

2004-01-01

The most important commercialized methods of attenuation correction in SPECT are based on attenuation coefficient map from a transmission imaging method. The transmission imaging system can be the linear source of radioelement or a X-ray CT system. The image of transmission imaging system is not useful unless to replacement of the attenuation coefficient or CT number with the attenuation coefficient in SPECT energy. In this paper we essay to evaluate the validity and estimate the error of the most used method of this transformation. The final result shows that the methods which use a linear or multi-linear curve accept a error in their estimation. The value of mA is not important but the patient thickness is very important and it can introduce a error more than 10 percent in the final result

Apparent Diffusion Coefficient Measurement in Mediastinal Lymphadenopathies: Differentiation between Benign and Malignant Lesions

Directory of Open Access Journals (Sweden)

Fethi Emre Ustabasioglu

2017-01-01

Full Text Available Objectives: We aimed to prospectively assess the diagnostic value of apparent diffusion coefficient (ADC measurement in the differentiation of benign and malignant mediastinal lymphadenopathies. Materials and Methods: The study included 63 consecutive patients (28 women, 35 men; mean age 59.3 years with 125 mediastinal lymphadenopathies. Echoplanar diffusion-weighted magnetic resonance imaging of the mediastinum was performed with b-factors of 0 and 600 mm2/s before mediastinoscopy and mediastinotomy, and ADC values were measured. The ADC values were compared with the histological results, and statistical analysis was done. P < 0.05 was considered statistically significant. Results: The mean ADC value of malignant mediastinal lymphadenopathy (1.030 ± 0.245 × 10−3 mm2/s was significantly lower (P < 0.05 when compared to benign lymphadenopathies (1.571 ± 0.559 × 10−3 mm2/s. For differentiating malignant from benign mediastinal lymphadenopathy, the best result was obtained when an ADC value of 1.334 × 10−3 mm2/s was used as a threshold value; area under the curve 0.848, accuracy 78.4%, sensitivity 66%, specificity of 86%, positive predictive value 76.7%, and negative predictive value of 79.2%. Interobserver agreement was excellent for ADC measurements. Conclusions: ADC measurements could be considered an important supportive method in differentiating benign from malignant mediastinal lymphadenopathies.

Internal conversion theory of gamma radiation in unfilled atomic shells

International Nuclear Information System (INIS)

Anderson, Eh.M.; Trusov, V.F.; Ehglajs, M.O.

1980-01-01

The internal conversion theory of gamma radiation in unfilled shells, when the atom is in a state with certain energy and momentum, is considered. A formula for the conversion coefficient between the atom and ion levels is obtained. This coefficient turns to be dependent on genealogic characteristics of the atom. It is discussed when the conversion coefficients are proportional to the numbers of filling subshells in the atom. Exact calculations have been carried out in the multiconfigurational approximation taking into account intermediate coupling for the d-shell of the Fe atom Single-electron radial wave functions have been calculated on the basis of the relativistic method of the Hartree-Fock-Dirak self-consistent field. Conversion coefficients on certain subshells as well as submatrix elements of the production operator are calculated. The electric coefficient of internal conversion (CIC) in the calculation for one electron does not depend on spin orientation. That is why the electric CIC from the level will not depend on filling number distribution by subshells. For magnetic CIC the dependence on the atom state is significant. Using multiconfiguration basis for calculating energy matrix and its succeeding diagonalization means the account of the intermediate coupling type, which takes place for the unfilled shells

Accuracy of apparent diffusion coefficient in differentiating pancreatic neuroendocrine tumour from intrapancreatic accessory spleen

International Nuclear Information System (INIS)

Pandey, Ankur; Pandey, Pallavi; Ghasabeh, Mounes Aliyari; Varzaneh, Farnaz Najmi; Khoshpouri, Pegah; Shao, Nannan; Pour, Manijeh Zargham; Fouladi, Daniel Fadaei; Kamel, Ihab R.; Hruban, Ralph H.; O'Broin-Lennon, Anne Marie

2018-01-01

To evaluate and compare the accuracy of absolute apparent diffusion coefficient (ADC) and normalised ADC (lesion-to-spleen ADC ratio) in differentiating pancreatic neuroendocrine tumour (NET) from intrapancreatic accessory spleen (IPAS). Study included 62 patients with the diagnosis of pancreatic NET (n=51) or IPAS (n=11). Two independent reviewers measured ADC on all lesions and spleen. Receiver operating characteristics (ROC) analysis to differentiate NET from IPAS was performed and compared for absolute and normalised ADC. Inter-reader reliability for the two methods was assessed. Pancreatic NET had significantly higher absolute ADC (1.431 x 10 -3 vs 0.967 x 10 -3 mm 2 /s; P<0.0001) and normalised ADC (1.59 vs 1.09; P<0.0001) compared to IPAS. An ADC value of ≥1.206 x 10 -3 mm 2 /s was 70.6% sensitive and 90.9% specific for the diagnosis of NET vs. IPAS. Lesion to spleen ADC ratio of ≥1.25 was 80.4% sensitive, and 81.8% specific while ratio of ≥1.29 was 74.5% sensitive and 100% specific in the differentiation. The area under the curve (AUCs) for two methods were similar (88.2% vs. 88.8%; P=0.899). Both methods demonstrated excellent inter-reader reliability with ICCs for absolute ADC and ADC ratio being 0.957 and 0.927, respectively. Both absolute and normalised ADC allow clinically relevant differentiation of pancreatic NET and IPAS. (orig.)

All-optical differential equation solver with constant-coefficient tunable based on a single microring resonator.

Science.gov (United States)

Yang, Ting; Dong, Jianji; Lu, Liangjun; Zhou, Linjie; Zheng, Aoling; Zhang, Xinliang; Chen, Jianping

2014-07-04

Photonic integrated circuits for photonic computing open up the possibility for the realization of ultrahigh-speed and ultra wide-band signal processing with compact size and low power consumption. Differential equations model and govern fundamental physical phenomena and engineering systems in virtually any field of science and engineering, such as temperature diffusion processes, physical problems of motion subject to acceleration inputs and frictional forces, and the response of different resistor-capacitor circuits, etc. In this study, we experimentally demonstrate a feasible integrated scheme to solve first-order linear ordinary differential equation with constant-coefficient tunable based on a single silicon microring resonator. Besides, we analyze the impact of the chirp and pulse-width of input signals on the computing deviation. This device can be compatible with the electronic technology (typically complementary metal-oxide semiconductor technology), which may motivate the development of integrated photonic circuits for optical computing.

Monte Carlo Method in the calculate of conversion coefficients for dose in children's organs and tissues subjected to dentistric radiography

International Nuclear Information System (INIS)

Loureiro, E.C.M.; Khoury, H.; Lima, F.R.A.

1998-01-01

The increasing utilization of oral X-rays, specially in youngsters and children, prompts the assessment of equivalent doses in their organs and tissues. With this purpose, Monte Carlo code was adopted to simulate an X-ray source irradiating phantoms of the MIRD-5 type with different ages (10, 15 and 40 years old) to calculate the conversion coefficients which transform the exposure at skin to equivalent doses at several organs and tissues of interest. In order to check the computer program, simulations were performed for adult patients using the original code (ADAM,FOR developed by GSF Germany) and the adapted program (MCDRO,PAS). Good agreement between results obtained by both programs was observed. Applications to incisive, canine and molar teeth were simulated. The conversion factors were calculated for the following organs and tissues: thyroid, active bone marrow (head and whole body), bone (facial skeleton, cranium and whole body), skin (head and whole body) and crystalline. Based on the obtained results, it follows that the younger the patient and the langer the field area, the higher the doses in assessed organs and tissues

Conversion coefficients for determination of dispersed photon dose during radiotherapy: NRUrad input code for MCNP.

Science.gov (United States)

Shahmohammadi Beni, Mehrdad; Ng, C Y P; Krstic, D; Nikezic, D; Yu, K N

2017-01-01

Radiotherapy is a common cancer treatment module, where a certain amount of dose will be delivered to the targeted organ. This is achieved usually by photons generated by linear accelerator units. However, radiation scattering within the patient's body and the surrounding environment will lead to dose dispersion to healthy tissues which are not targets of the primary radiation. Determination of the dispersed dose would be important for assessing the risk and biological consequences in different organs or tissues. In the present work, the concept of conversion coefficient (F) of the dispersed dose was developed, in which F = (Dd/Dt), where Dd was the dispersed dose in a non-targeted tissue and Dt is the absorbed dose in the targeted tissue. To quantify Dd and Dt, a comprehensive model was developed using the Monte Carlo N-Particle (MCNP) package to simulate the linear accelerator head, the human phantom, the treatment couch and the radiotherapy treatment room. The present work also demonstrated the feasibility and power of parallel computing through the use of the Message Passing Interface (MPI) version of MCNP5.

Establishment of detailed eye model of adult chinese male and dose conversion coefficients calculation under neutron exposure

International Nuclear Information System (INIS)

Zhu, Hongyu; Qiu, Rui; Ren, Li; Zhang, Hui; Li, Junli; Wu, Zhen; Li, Chunyan

2017-01-01

The human eye lens is sensitive to radiation. ICRP-118 publication recommended a reduction of the occupational annual equivalent dose limit from 150 to 20 mSv, averaged over defined periods of 5 y. Therefore, it is very important to build a detailed eye model for the accurate dose assessment and radiation risk evaluation of eye lens. In this work, a detailed eye model was build based on the characteristic anatomic parameters of the Chinese adult male. This eye model includes seven main structures, which are scleral, choroid, lens, iris, cornea, vitreous body and aqueous humor. The lens was divided into sensitive volume and insensitive volume based on different cell populations. The detailed eye model was incorporated into the converted polygon-mesh version of the Chinese reference adult male whole-body surface model. After the incorporation, dose conversion coefficients for the eye lens were calculated for neutron exposure at AP, PA and LAT geometries with Geant4, the neutron energies were from 0.001 eV to 10 MeV. The calculated lens dose coefficients were compared with those of ICRP-116 publication. Significant differences up to 97.47% were found at PA geometry. This could mainly be attributed to the different geometry characteristic of eye model and parameters of head in different phantom between the present work and ICRP-116 publication. (authors)

Comparison of conversion coefficients for equivalent dose in terms of air kerma using a sitting and standing female adult voxel simulators exposure to photons in antero-posterior irradiation geometry

International Nuclear Information System (INIS)

Cavalcante, F.R.; Galeano, D.C.; Carvalho Júnior, A.B.; Hunt, J.

2014-01-01

Due to the difficulty in implementing invasive techniques for calculations of dose for some exposure scenarios, computational simulators have been created to represent as realistically as possible the structures of the human body and through radiation transport simulations to obtain conversion coefficients (CCs) to estimate dose. In most published papers simulators are implemented in the standing posture and this may not describe a real scenario of exposure. In this work we developed exposure scenarios in the Visual Monte Carlo (VMC) code using a female simulator in standing and sitting postures. The simulator was irradiated in the antero-posterior (AP) geometry by a plane source of monoenergetic photons with energy from 10 keV to 2 MeV. The conversion coefficients for equivalent dose in terms of air kerma (H T /K air ) were calculated for both scenarios and compared. The results show that the percentage difference of CCs for the organs of the head and thorax was not significant (less than 5%) since the anatomic position of the organs is the same in both postures. The percentage difference is more significant to the ovaries (71% for photon energy of 20 keV), to the bladder (39% at 60 keV) and to the uterus (37% at 100 keV) due to different processes of radiation interactions in the legs of the simulator when its posture is changed. For organs and tissues that are distributed throughout the entire body, such as bone (21% at 100 keV) and muscle (30% at 80 keV) the percentage difference of CCs reflects a reduction of interaction of photons with the legs of the simulator. Therefore, the calculation of conversion coefficients using simulators in the sitting posture is relevant for a more accurate dose estimation in real exposures to radiation. - Highlights: ► Scenarios of external photon exposures were performed in VMC code. ► The FAX simulator was irradiated in sitting and standing postures. ► The irradiation geometry used was the antero-posterior (AP). ► The

Temperature dependence of mode conversion in warm, unmagnetized plasmas with a linear density profile

Energy Technology Data Exchange (ETDEWEB)

Yu, Dae Jung; Lee, Dong-Hun [School of Space Research, Kyung Hee University, Yongin (Korea, Republic of); Kim, Kihong [Division of Energy Systems Research, Ajou University, Suwon (Korea, Republic of)

2013-06-15

We study theoretically the linear mode conversion between electromagnetic waves and Langmuir waves in warm, stratified, and unmagnetized plasmas, using a numerically precise calculation based on the invariant imbedding method. We verify that the principle of reciprocity for the forward and backward mode conversion coefficients holds precisely regardless of temperature. We also find that the temperature dependence of the mode conversion coefficient is substantially stronger than that previously reported. Depending on the wave frequency and the incident angle, the mode conversion coefficient is found to increase or decrease with the increase of temperature.

Novel Exponentially Fitted Two-Derivative Runge-Kutta Methods with Equation-Dependent Coefficients for First-Order Differential Equations

Directory of Open Access Journals (Sweden)

Yanping Yang

2016-01-01

Full Text Available The construction of exponentially fitted two-derivative Runge-Kutta (EFTDRK methods for the numerical solution of first-order differential equations is investigated. The revised EFTDRK methods proposed, with equation-dependent coefficients, take into consideration the errors produced in the internal stages to the update. The local truncation errors and stability of the new methods are analyzed. The numerical results are reported to show the accuracy of the new methods.

ADC histogram analysis for adrenal tumor histogram analysis of apparent diffusion coefficient in differentiating adrenal adenoma from pheochromocytoma.

Science.gov (United States)

Umanodan, Tomokazu; Fukukura, Yoshihiko; Kumagae, Yuichi; Shindo, Toshikazu; Nakajo, Masatoyo; Takumi, Koji; Nakajo, Masanori; Hakamada, Hiroto; Umanodan, Aya; Yoshiura, Takashi

2017-04-01

To determine the diagnostic performance of apparent diffusion coefficient (ADC) histogram analysis in diffusion-weighted (DW) magnetic resonance imaging (MRI) for differentiating adrenal adenoma from pheochromocytoma. We retrospectively evaluated 52 adrenal tumors (39 adenomas and 13 pheochromocytomas) in 47 patients (21 men, 26 women; mean age, 59.3 years; range, 16-86 years) who underwent DW 3.0T MRI. Histogram parameters of ADC (b-values of 0 and 200 [ADC 200 ], 0 and 400 [ADC 400 ], and 0 and 800 s/mm 2 [ADC 800 ])-mean, variance, coefficient of variation (CV), kurtosis, skewness, and entropy-were compared between adrenal adenomas and pheochromocytomas, using the Mann-Whitney U-test. Receiver operating characteristic (ROC) curves for the histogram parameters were generated to differentiate adrenal adenomas from pheochromocytomas. Sensitivity and specificity were calculated by using a threshold criterion that would maximize the average of sensitivity and specificity. Variance and CV of ADC 800 were significantly higher in pheochromocytomas than in adrenal adenomas (P histogram parameters for diagnosing adrenal adenomas (ADC 200 , 0.82; ADC 400 , 0.87; and ADC 800 , 0.92), with sensitivity of 84.6% and specificity of 84.6% (cutoff, ≤2.82) with ADC 200 ; sensitivity of 89.7% and specificity of 84.6% (cutoff, ≤2.77) with ADC 400 ; and sensitivity of 94.9% and specificity of 92.3% (cutoff, ≤2.67) with ADC 800 . ADC histogram analysis of DW MRI can help differentiate adrenal adenoma from pheochromocytoma. 3 J. Magn. Reson. Imaging 2017;45:1195-1203. © 2016 International Society for Magnetic Resonance in Medicine.

Monte Carlo determination of the conversion coefficients Hp(3)/Ka in a right cylinder phantom with 'PENELOPE' code. Comparison with 'MCNP' simulations.

Science.gov (United States)

Daures, J; Gouriou, J; Bordy, J M

2011-03-01

This work has been performed within the frame of the European Union ORAMED project (Optimisation of RAdiation protection for MEDical staff). The main goal of the project is to improve standards of protection for medical staff for procedures resulting in potentially high exposures and to develop methodologies for better assessing and for reducing, exposures to medical staff. The Work Package WP2 is involved in the development of practical eye-lens dosimetry in interventional radiology. This study is complementary of the part of the ENEA report concerning the calculations with the MCNP-4C code of the conversion factors related to the operational quantity H(p)(3). In this study, a set of energy- and angular-dependent conversion coefficients (H(p)(3)/K(a)), in the newly proposed square cylindrical phantom made of ICRU tissue, have been calculated with the Monte-Carlo code PENELOPE and MCNP5. The H(p)(3) values have been determined in terms of absorbed dose, according to the definition of this quantity, and also with the kerma approximation as formerly reported in ICRU reports. At a low-photon energy (up to 1 MeV), the two results obtained with the two methods are consistent. Nevertheless, large differences are showed at a higher energy. This is mainly due to the lack of electronic equilibrium, especially for small angle incidences. The values of the conversion coefficients obtained with the MCNP-4C code published by ENEA quite agree with the kerma approximation calculations obtained with PENELOPE. We also performed the same calculations with the code MCNP5 with two types of tallies: F6 for kerma approximation and *F8 for estimating the absorbed dose that is, as known, due to secondary electrons. PENELOPE and MCNP5 results agree for the kerma approximation and for the absorbed dose calculation of H(p)(3) and prove that, for photon energies larger than 1 MeV, the transport of the secondary electrons has to be taken into account.

ESTABLISHMENT OF DETAILED EYE MODEL OF ADULT CHINESE MALE AND DOSE CONVERSION COEFFICIENTS CALCULATION UNDER NEUTRON EXPOSURE.

Science.gov (United States)

Zhu, Hongyu; Qiu, Rui; Wu, Zhen; Ren, Li; Li, Chunyan; Zhang, Hui; Li, Junli

2017-12-01

The human eye lens is sensitive to radiation. ICRP-118 publication recommended a reduction of the occupational annual equivalent dose limit from 150 to 20 mSv, averaged over defined periods of 5 y. Therefore, it is very important to build a detailed eye model for the accurate dose assessment and radiation risk evaluation of eye lens. In this work, a detailed eye model was build based on the characteristic anatomic parameters of the Chinese adult male. This eye model includes seven main structures, which are scleral, choroid, lens, iris, cornea, vitreous body and aqueous humor. The lens was divided into sensitive volume and insensitive volume based on different cell populations. The detailed eye model was incorporated into the converted polygon-mesh version of the Chinese reference adult male whole-body surface model. After the incorporation, dose conversion coefficients for the eye lens were calculated for neutron exposure at AP, PA and LAT geometries with Geant4, the neutron energies were from 0.001 eV to 10 MeV. The calculated lens dose coefficients were compared with those of ICRP-116 publication. Significant differences up to 97.47% were found at PA geometry. This could mainly be attributed to the different geometry characteristic of eye model and parameters of head in different phantom between the present work and ICRP-116 publication. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

A Whole-Tumor Histogram Analysis of Apparent Diffusion Coefficient Maps for Differentiating Thymic Carcinoma from Lymphoma.

Science.gov (United States)

Zhang, Wei; Zhou, Yue; Xu, Xiao-Quan; Kong, Ling-Yan; Xu, Hai; Yu, Tong-Fu; Shi, Hai-Bin; Feng, Qing

2018-01-01

To assess the performance of a whole-tumor histogram analysis of apparent diffusion coefficient (ADC) maps in differentiating thymic carcinoma from lymphoma, and compare it with that of a commonly used hot-spot region-of-interest (ROI)-based ADC measurement. Diffusion weighted imaging data of 15 patients with thymic carcinoma and 13 patients with lymphoma were retrospectively collected and processed with a mono-exponential model. ADC measurements were performed by using a histogram-based and hot-spot-ROI-based approach. In the histogram-based approach, the following parameters were generated: mean ADC (ADC mean ), median ADC (ADC median ), 10th and 90th percentile of ADC (ADC 10 and ADC 90 ), kurtosis, and skewness. The difference in ADCs between thymic carcinoma and lymphoma was compared using a t test. Receiver operating characteristic analyses were conducted to determine and compare the differentiating performance of ADCs. Lymphoma demonstrated significantly lower ADC mean , ADC median , ADC 10 , ADC 90 , and hot-spot-ROI-based mean ADC than those found in thymic carcinoma (all p values histogram analysis of ADC maps can improve the differentiating performance between thymic carcinoma and lymphoma.

Hp(3)/Φ conversion coefficients for neutrons: discussion on the basis of the new ICRP recommended limit for the eye lens

International Nuclear Information System (INIS)

Ferrari, P.; Gualdrini, G.; Fantuzzi, E.; Tanner, R.

2014-01-01

The new recommendation issued by the International Commission on Radiological Protection (ICRP) introducing a 20-mSv annual dose limit for the eye lens stimulated an interesting debate among the radiation protection community. In the present work the problem of estimating H p (3) for neutron realistic workplace spectra is treated, employing the recently published H p (3)/Φ conversion coefficients with the aim of establishing a workplace-dependent relationship between H p (10) and H p (3). The results demonstrate that, whilst the two quantities can differ by less than 10 %, in general, H p (10) cannot be considered a conservative estimate of H p (3). The present study was conducted to find out whether it is possible to derive H p (3) from H p (10) measurements/determinations in neutron workplace fields using the relationship that can be established between the conversion coefficients H p (3)/Φ and H p (10)/Φ evaluated for monoenergetic neutron beams. Several real cases, taken from the IAEA neutron source compendium, were investigated and, in general, it can be conclude that H p (10) is seldom a conservative estimate of H p (3) (only at 0 deg. and in one case, among the treated spectra, H p (10)/Φ is higher than H p (3)/Φ). Indeed, care should be taken if one tries to derive directly such a correction factor from tabulations of neutron monoenergetic plots of conversion coefficients, on the basis of the mean energy, because in case of really degraded spectra (as in the heavy shielded situation) the mean energy, as expected, could be a too rough a parameter. However, in general, for 0 deg., antero-posterior irradiation condition, which is expected to be a quite common working condition, H p (10) underestimation is of the order of 10 % thus, at least, a correction factor of 1.1 should be applied to H p (10) in order to estimate the 'corresponding' H p (3). For irradiation conditions far from the normal incidence for which the underestimation can be as high as 60

Solving Variable Coefficient Fourth-Order Parabolic Equation by ...

African Journals Online (AJOL)

Solving Variable Coefficient Fourth-Order Parabolic Equation by Modified initial guess Variational ... variable coefficient fourth order parabolic partial differential equations. The new method shows rapid convergence to the exact solution.

Total conversion coefficient of the 263 keV (21/sup 2//2->13/sup +//2) transition in sup(93m)Mo

Energy Technology Data Exchange (ETDEWEB)

Suryanaryana, C.; Venkateswara Rao, M.; Narayana, D.G.S.; Bhuloka Reddy, S.; Satyanarayana, G.; Sastry, D.L.; Chintalapudi, S.N.

1985-01-01

The total conversion coefficient of the 263 keV gamma transition in the decay scheme of sup(93m)Mo is measured by intensity balance method using a HP Ge spectrometer system. The experimental value of ..cap alpha..sub(T)(263 keV) is found to be 0.696 +- 0.05 which is in agreement with the theoretical values 0.72 and 0.7. The transition probability T(E4) is calculated using the present value of ..cap alpha..sub(T) and compared with the single-particle estimate. A good agreement is noted between the theory and the experiment for the value of T(E4).

A new fifth parameter for transverse isotropy III: reflection and transmission coefficients

Science.gov (United States)

Kawakatsu, Hitoshi

2018-04-01

The effect of the newly defined fifth parameter, ηκ, of transverse anisotropy to the reflection and transmission coefficients, especially for P-to-S and S-to-P conversion coefficients, is examined. While ηκ systematically affects the P-to-S and S-to-P conversions, in the incidence angle range of the practical interest of receiver function studies, the effect may be asymmetric in a sense that P-wave receiver function is affected more than S-receiver function in terms of amplitude. This asymmetry may help resolving ηκ via extensive receiver function analysis. It is also found that P-wave anisotropy significantly influences P-to-S and S-to-P conversion coefficients that complicates the interpretation of receiver functions, because, for isotropic media, we typically attribute the primary receiver function signals to S-wave velocity changes but not to P-wave changes.

Methods for locating ground faults and insulation degradation condition in energy conversion systems

Science.gov (United States)

Agamy, Mohamed; Elasser, Ahmed; Galbraith, Anthony William; Harfman Todorovic, Maja

2015-08-11

Methods for determining a ground fault or insulation degradation condition within energy conversion systems are described. A method for determining a ground fault within an energy conversion system may include, in part, a comparison of baseline waveform of differential current to a waveform of differential current during operation for a plurality of DC current carrying conductors in an energy conversion system. A method for determining insulation degradation within an energy conversion system may include, in part, a comparison of baseline frequency spectra of differential current to a frequency spectra of differential current transient at start-up for a plurality of DC current carrying conductors in an energy conversion system. In one embodiment, the energy conversion system may be a photovoltaic system.

Towards the reanalysis of void coefficients measurements at proteus for high conversion light water reactor lattices

Energy Technology Data Exchange (ETDEWEB)

Hursin, M.; Koeberl, O.; Perret, G. [Paul Scherrer Institut PSI, 5232 Villigen (Switzerland)

2012-07-01

High Conversion Light Water Reactors (HCLWR) allows a better usage of fuel resources thanks to a higher breeding ratio than standard LWR. Their uses together with the current fleet of LWR constitute a fuel cycle thoroughly studied in Japan and the US today. However, one of the issues related to HCLWR is their void reactivity coefficient (VRC), which can be positive. Accurate predictions of void reactivity coefficient in HCLWR conditions and their comparisons with representative experiments are therefore required. In this paper an inter comparison of modern codes and cross-section libraries is performed for a former Benchmark on Void Reactivity Effect in PWRs conducted by the OECD/NEA. It shows an overview of the k-inf values and their associated VRC obtained for infinite lattice calculations with UO{sub 2} and highly enriched MOX fuel cells. The codes MCNPX2.5, TRIPOLI4.4 and CASMO-5 in conjunction with the libraries ENDF/B-VI.8, -VII.0, JEF-2.2 and JEFF-3.1 are used. A non-negligible spread of results for voided conditions is found for the high content MOX fuel. The spread of eigenvalues for the moderated and voided UO{sub 2} fuel are about 200 pcm and 700 pcm, respectively. The standard deviation for the VRCs for the UO{sub 2} fuel is about 0.7% while the one for the MOX fuel is about 13%. This work shows that an appropriate treatment of the unresolved resonance energy range is an important issue for the accurate determination of the void reactivity effect for HCLWR. A comparison to experimental results is needed to resolve the presented discrepancies. (authors)

Conversion Disorder Presenting As Neuritic Leprosy

Directory of Open Access Journals (Sweden)

Sayal SK

2000-01-01

Full Text Available Conversion disorder is not normally listed amongst the conditions in differential diagnosis of leprosy neuropathy. A case conversion reaction who was initially diagnosed as neuritic leprosy is reported. Patient responded to narcosuggestion and psychotherapy.

A combination between the differential and the perturbation theory methods for calculating sensitivity coefficients; Uma combinacao entre os metodos diferencial e da teoria de pertubacao para o calculo dos coeficientes de sensibilidade

Energy Technology Data Exchange (ETDEWEB)

Borges, Antonio Andrade

1998-07-01

A new method for the calculation of sensitivity coefficients is developed. The new method is a combination of two methodologies used for calculating theses coefficients, which are the differential and the generalized perturbation theory methods. The method utilizes as integral parameter the average flux in an arbitrary region of the system. Thus, the sensitivity coefficient contains only the component corresponding to the neutron flux. To obtain the new sensitivity coefficient, the derivatives of the integral parameter, {phi}, with respect to {sigma} are calculated using the perturbation method and the functional derivatives of this generic integral parameter with respect to {sigma} and {phi} are calculated using the differential method. (author)

The influence of the b-value combination on apparent diffusion coefficient based differentiation between malignant and benign tissue in cervical cancer

NARCIS (Netherlands)

Hoogendam, Jacob P.; Klerkx, Wenche M.; de Kort, Gerard A. P.; Bipat, Shandra; Zweemer, Ronald P.; Sie-Go, Daisy M. D. S.; Verheijen, René H. M.; Mali, Willem P. T. M.; Veldhuis, Wouter B.

2010-01-01

To analyze the influence of different b-value combinations on apparent diffusion coefficient (ADC)-based differentiation of known malignant and benign tissue in cervical cancer patients. A total of 35 patients with stage IB1, IB2, IIA cervical cancer underwent a 3.0T MRI scan prior to radical

Comparison of effective transverse piezoelectric coefficients e31,f of Pb(Zr,Ti)O3 thin films between direct and converse piezoelectric effects

Science.gov (United States)

Tsujiura, Yuichi; Kawabe, Saneyuki; Kurokawa, Fumiya; Hida, Hirotaka; Kanno, Isaku

2015-10-01

We evaluated the effective transverse piezoelectric coefficients (e31,f) of Pb(Zr,Ti)O3 (PZT) thin films from both the direct and converse piezoelectric effects of unimorph cantilevers. (001) preferentially oriented polycrystalline PZT thin films and (001)/(100) epitaxial PZT thin films were deposited on (111)Pt/Ti/Si and (001)Pt/MgO substrates, respectively, by rf-magnetron sputtering, and their piezoelectric responses owing to intrinsic and extrinsic effects were examined. The direct and converse |e31,f| values of the polycrystalline PZT thin films were calculated as 6.4 and 11.5-15.0 C/m2, respectively, whereas those of the epitaxial PZT thin films were calculated as 3.4 and 4.6-4.8 C/m2, respectively. The large |e31,f| of the converse piezoelectric property of the polycrystalline PZT thin films is attributed to extrinsic piezoelectric effects. Furthermore, the polycrystalline PZT thin films show a clear nonlinear piezoelectric contribution, which is the same as the Rayleigh-like behavior reported in bulk PZT. In contrast, the epitaxial PZT thin films on the MgO substrate show a piezoelectric response owing to the intrinsic and linear extrinsic effects, and no nonlinear contribution was observed.

A differential evolution algorithm for tooth profile optimization with respect to balancing specific sliding coefficients of involute cylindrical spur and helical gears

Directory of Open Access Journals (Sweden)

Hammoudi Abderazek

2015-09-01

Full Text Available Profile shift has an immense effect on the sliding, load capacity, and stability of involute cylindrical gears. Available standards such as ISO/DIS 6336 and BS 436 DIN/3990 currently give the recommendation for the selection of profile shift coefficients. It is, however, very approximate and usually given in the form of implicit graphs or charts. In this article, the optimal selection values of profile shift coefficients for cylindrical involute spur and helical gears are described, using a differential evolution algorithm. The optimization procedure is developed specifically for exact balancing specific sliding coefficients at extremes of contact path and account for gear design constraints. The obtained results are compared with those of standards and research of other authors. They demonstrate the effectiveness and robustness of the applied method. A substantial improvement in balancing specific sliding coefficients is found in this work.

Basis adaptation and domain decomposition for steady-state partial differential equations with random coefficients

Energy Technology Data Exchange (ETDEWEB)

Tipireddy, R.; Stinis, P.; Tartakovsky, A. M.

2017-12-01

We present a novel approach for solving steady-state stochastic partial differential equations (PDEs) with high-dimensional random parameter space. The proposed approach combines spatial domain decomposition with basis adaptation for each subdomain. The basis adaptation is used to address the curse of dimensionality by constructing an accurate low-dimensional representation of the stochastic PDE solution (probability density function and/or its leading statistical moments) in each subdomain. Restricting the basis adaptation to a specific subdomain affords finding a locally accurate solution. Then, the solutions from all of the subdomains are stitched together to provide a global solution. We support our construction with numerical experiments for a steady-state diffusion equation with a random spatially dependent coefficient. Our results show that highly accurate global solutions can be obtained with significantly reduced computational costs.

Calculation of neutron fluence to dose equivalent conversion coefficients using GEANT4; Calculo de coeficientes de fluencia de neutrons para equivalente de dose individual utilizando o GEANT4

Energy Technology Data Exchange (ETDEWEB)

Ribeiro, Rosane M.; Santos, Denison de S.; Queiroz Filho, Pedro P. de; Mauricio, CLaudia L.P.; Silva, Livia K. da; Pessanha, Paula R., E-mail: rosanemribeiro@oi.com.br [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil)

2014-07-01

Fluence to dose equivalent conversion coefficients provide the basis for the calculation of area and personal monitors. Recently, the ICRP has started a revision of these coefficients, including new Monte Carlo codes for benchmarking. So far, little information is available about neutron transport below 10 MeV in tissue-equivalent (TE) material performed with Monte Carlo GEANT4 code. The objective of this work is to calculate neutron fluence to personal dose equivalent conversion coefficients, H{sub p} (10)/Φ, with GEANT4 code. The incidence of monoenergetic neutrons was simulated as an expanded and aligned field, with energies ranging between thermal neutrons to 10 MeV on the ICRU slab of dimension 30 x 30 x 15 cm{sup 3}, composed of 76.2% of oxygen, 10.1% of hydrogen, 11.1% of carbon and 2.6% of nitrogen. For all incident energy, a cylindrical sensitive volume is placed at a depth of 10 mm, in the largest surface of the slab (30 x 30 cm{sup 2}). Physic process are included for neutrons, photons and charged particles, and calculations are made for neutrons and secondary particles which reach the sensitive volume. Results obtained are thus compared with values published in ICRP 74. Neutron fluence in the sensitive volume was calculated for benchmarking. The Monte Carlo GEANT4 code was found to be appropriate to calculate neutron doses at energies below 10 MeV correctly. (author)

Apparent diffusion coefficient measurements in the differentiation between benign and malignant lesions: a systematic review.

Science.gov (United States)

Vermoolen, M A; Kwee, T C; Nievelstein, R A J

2012-08-01

To systematically review the value of apparent diffusion coefficient (ADC) measurement in the differentiation between benign and malignant lesions. A systematic search of the Medline/Pubmed and Embase databases revealed 109 relevant studies. Quality of these articles was assessed using the Quality Assessment of the Studies of Diagnostic Accuracy Included in Systematic Reviews (QUADAS) criteria. Reported ADC values of benign and malignant lesions were compared per organ. The mean quality score of the reviewed articles was 50%. Comparison of ADC values showed marked variation among studies and between benign and malignant lesions in various organs. In several organs, such as breast, liver, and uterus, ADC values discriminated well between benign and malignant lesions. In other organs, such as the salivary glands, thyroid, and pancreas, ADCs were not significantly different between benign and malignant lesions. The potential utility of ADC measurement for the characterisation of tumours differs per organ. Future well-designed studies are required before ADC measurements can be recommended for the differentiation of benign and malignant lesions. These future studies should use standardised acquisition protocols and provide complete reporting of study methods, to facilitate comparison of results and clinical implementation of ADC measurement for tumour characterisation.

Whole-tumor apparent diffusion coefficient (ADC) histogram analysis to differentiate benign peripheral neurogenic tumors from soft tissue sarcomas.

Science.gov (United States)

Nakajo, Masanori; Fukukura, Yoshihiko; Hakamada, Hiroto; Yoneyama, Tomohide; Kamimura, Kiyohisa; Nagano, Satoshi; Nakajo, Masayuki; Yoshiura, Takashi

2018-02-22

Apparent diffusion coefficient (ADC) histogram analyses have been used to differentiate tumor grades and predict therapeutic responses in various anatomic sites with moderate success. To determine the ability of diffusion-weighted imaging (DWI) with a whole-tumor ADC histogram analysis to differentiate benign peripheral neurogenic tumors (BPNTs) from soft tissue sarcomas (STSs). Retrospective study, single institution. In all, 25 BPNTs and 31 STSs. Two-b value DWI (b-values = 0, 1000s/mm 2 ) was at 3.0T. The histogram parameters of whole-tumor for ADC were calculated by two radiologists and compared between BPNTs and STSs. Nonparametric tests were performed for comparisons between BPNTs and STSs. P histogram parameters except kurtosis and entropy differed significantly between BPNTs and STSs. 3 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2018. © 2018 International Society for Magnetic Resonance in Medicine.

Total internal conversion coefficient of the 260. 9 keV (7/sup +/->3/sup -/) transition in sup(198m)Tl

Energy Technology Data Exchange (ETDEWEB)

Venkateswara Rao, N.; Suryanarayana, C.; Narayana, D.G.S.; Bhuloka Reddy, S.; Satynarayana, G.; Sastry, D.L.; Chintalapudi, S.N.

1986-02-21

The 1.87 hours 543.7 keV (7/sup +/) isomeric state in /sup 198/Tl is produced via /sup 197/Au(..cap alpha.., 3n)sup(198m)Tl (Esub(..cap alpha..) = 35 MeV) reaction. The total conversion coefficient of 260.9 keV (7/sup +/ -> 3/sup -/) is determined for the first time by the intensity balance method. The value of ..cap alpha..sub(T)(260.9 keV) is found to be 40.1 +- 8.6 which is in good agreement with the theoretical value of Hager and Seltzer for pure M4 transition. The gamma transition probability of the 260.9 keV (M4) is calculated using the present value of ..cap alpha..sub(T) and compared with the single-particle estimate.

Conversion of the 42 keV transition in the decay of 191Os

International Nuclear Information System (INIS)

Bhuloka Reddy, S.; Narasimham, K.L.; Thirumala Rao, B.V.; Lakshminarayana, V.

1986-01-01

The total as well as the L-conversion coefficient of the 42 KeV transition in the decay of 191 Os are determined from intensity balance considerations and XPG technique, respectively, using a 3 mm Si(Li) detector system. The resultant values are αsub(T) = 13709 (1900), αsub(L) = 11700 (2100). The present total conversion coefficients shows good agreement within the uncertainty limits, with the value αsub(T) = 13.500→ 5200 +21100 reported by Lange, whereas the L-conversion coefficient is reported for the first time. Our present values are also compared with the theoretical values interpolated from the tables of Hager and Seltzer and of Rosel et al

Audio watermarking robust against D/A and A/D conversions

Directory of Open Access Journals (Sweden)

Xiang Shijun

2011-01-01

Full Text Available Abstract Digital audio watermarking robust against digital-to-analog (D/A and analog-to-digital (A/D conversions is an important issue. In a number of watermark application scenarios, D/A and A/D conversions are involved. In this article, we first investigate the degradation due to DA/AD conversions via sound cards, which can be decomposed into volume change, additional noise, and time-scale modification (TSM. Then, we propose a solution for DA/AD conversions by considering the effect of the volume change, additional noise and TSM. For the volume change, we introduce relation-based watermarking method by modifying groups of the energy relation of three adjacent DWT coefficient sections. For the additional noise, we pick up the lowest-frequency coefficients for watermarking. For the TSM, the synchronization technique (with synchronization codes and an interpolation processing operation is exploited. Simulation tests show the proposed audio watermarking algorithm provides a satisfactory performance to DA/AD conversions and those common audio processing manipulations.

Evaluation of dose conversion coefficients for external exposure using Taiwanese reference man and woman

International Nuclear Information System (INIS)

Chang, S.J.; Hung, S.Y.; Liu, Y.L.; Jiang, S.H.; Wu, J.

2015-01-01

Reference man has been widely used for external and internal dose evaluation of radiation protection. The parameters of the mathematical model of organs suggested by the International Commission of Radiological Protection (ICRP) are adopted from the average data of Caucasians. However, the organ masses of Asians are significantly different from the data of Caucasians, leading to potentially dosimetric errors. In this study, a total of 40 volunteers whose heights and weights corresponded to the statistical average of Taiwanese adults were recruited. Magnetic resonance imaging was performed, and T2-weighted images were acquired. The Taiwanese reference man and woman were constructed according to the measured organ masses. The dose conversion coefficients (DCFs) for anterior-posterior (AP), posterior-anterior (PA), right lateral (RLAT) and left lateral (LLAT) irradiation geometries were simulated. For the Taiwanese reference man, the average differences of the DCFs compared with the results of ICRP-74 were 7.6, 5.1 and 11.1 % for 0.1, 1 and 10 MeV photons irradiated in the AP direction. The maximum difference reached 51.7 % for the testes irradiated by 10 MeV photons. The size of the trunk, the volume and the geometric position of organs can cause a significant impact on the DCFs for external exposure of radiation. The constructed Taiwanese reference man and woman can be used in radiation protection to increase the accuracy of dose evaluation for the Taiwanese population. (authors)

Effects of conversion ratio change on the core performances in medium to large TRU burning reactors

International Nuclear Information System (INIS)

Song, Hoon; Kim, Sang-Ji; Yoo, Jae-Woon; Kim, Yeong-Il

2009-01-01

Conceptual fast reactor core designs with sodium coolant are developed at 1,500, 3,000 and 4,500 MWt which are configured to transmute recycled transuranics (TRU) elements with external feeds consisting of LWR spent fuel. Even at each pre-determined power level, the performance parameters, reactivity coefficients and their implications on the safety analysis can be different when the target TRU conversion ratio changes. In order to address this aspect of design, a study on TRU conversion ratio change was performed. The results indicate that it is feasible to design a TRU burner core to accommodate a wide range of conversion ratios by employing different fuel cladding thicknesses. The TRU consumption rate is found to be proportional to the core power without any significant deterioration in the core performance at higher power levels. A low conversion ratio core has an increased TRU consumption rate and much faster burnup reactivity loss, which calls for appropriate means for reactivity compensation. As for the reactivity coefficients related with the conversion ratio change, the core with a low conversion ratio has a less negative Doppler coefficient, a more negative axial expansion coefficient, a more negative control rod worth per rod, a more negative radial expansion coefficient, a less positive sodium density coefficient and a less positive sodium void worth. A slight decrease in the delayed neutron fraction is also noted, reflecting the fertile U-238 fraction reduction. (author)

Transport coefficients of InSb in a strong magnetic field

International Nuclear Information System (INIS)

Nakamura, Hiroaki; Ikeda, Kazuaki; Yamaguchi, Satarou

1998-02-01

Improvement of a superconducting magnet system makes induction of a strong magnetic field easier. This fact gives us a possibility of energy conversion by the Nernst effect. As the first step to study the Nernst element, we measured the conductivity, the Hall coefficient, the thermoelectric power and the Nernst coefficient of the InSb, which is one of candidates of the Nernst elements. From this experiment, it is concluded that the Nernst coefficient is smaller than the theoretical values. On the other hand, the conductivity, the Hall coefficient and the thermoelectric power has the values expected by the theory. (author)

A study on a characteristic of stem friction coefficient for motor operated flexible wedge gate valve

International Nuclear Information System (INIS)

Kim, Dae-Woong; Park, Sung-Geun; Lee, Sang-Guk; Kang, Shin-Cheul

2009-01-01

Stem friction coefficient is a coefficient that represents friction between thread leads of the stem and stem nut. It is an important factor to determine output thrust delivered from the actuator to the valve stem in assessing performance of motor operated valves. This study analyzes the effects of changes in differential pressure on stem friction coefficient, and determines the bounding value of stem friction coefficient. A dynamic test was conducted on multiple flexible wedge gate valves in various differential pressure conditions, and the test data was statistically analyzed to determine the bounding value. The results show that stem friction coefficient in middle and high differential pressure is influenced by fluid pressure, while stem friction coefficient in low differential pressure is almost not affected by fluid pressure. In addition, it is found that the bounding value of stem friction coefficient is higher in a closing stroke than in an opening stroke.

Dynamics with infinitely many derivatives: variable coefficient equations

International Nuclear Information System (INIS)

Barnaby, Neil; Kamran, Niky

2008-01-01

Infinite order differential equations have come to play an increasingly significant role in theoretical physics. Field theories with infinitely many derivatives are ubiquitous in string field theory and have attracted interest recently also from cosmologists. Crucial to any application is a firm understanding of the mathematical structure of infinite order partial differential equations. In our previous work we developed a formalism to study the initial value problem for linear infinite order equations with constant coefficients. Our approach relied on the use of a contour integral representation for the functions under consideration. In many applications, including the study of cosmological perturbations in nonlocal inflation, one must solve linearized partial differential equations about some time-dependent background. This typically leads to variable coefficient equations, in which case the contour integral methods employed previously become inappropriate. In this paper we develop the theory of a particular class of linear infinite order partial differential equations with variable coefficients. Our formalism is particularly well suited to the types of equations that arise in nonlocal cosmological perturbation theory. As an example to illustrate our formalism we compute the leading corrections to the scalar field perturbations in p-adic inflation and show explicitly that these are small on large scales.

A finite difference method for space fractional differential equations with variable diffusivity coefficient

KAUST Repository

Mustapha, K.

2017-06-03

Anomalous diffusion is a phenomenon that cannot be modeled accurately by second-order diffusion equations, but is better described by fractional diffusion models. The nonlocal nature of the fractional diffusion operators makes substantially more difficult the mathematical analysis of these models and the establishment of suitable numerical schemes. This paper proposes and analyzes the first finite difference method for solving {\\\\em variable-coefficient} fractional differential equations, with two-sided fractional derivatives, in one-dimensional space. The proposed scheme combines first-order forward and backward Euler methods for approximating the left-sided fractional derivative when the right-sided fractional derivative is approximated by two consecutive applications of the first-order backward Euler method. Our finite difference scheme reduces to the standard second-order central difference scheme in the absence of fractional derivatives. The existence and uniqueness of the solution for the proposed scheme are proved, and truncation errors of order $h$ are demonstrated, where $h$ denotes the maximum space step size. The numerical tests illustrate the global $O(h)$ accuracy of our scheme, except for nonsmooth cases which, as expected, have deteriorated convergence rates.

A finite difference method for space fractional differential equations with variable diffusivity coefficient

KAUST Repository

Mustapha, K.; Furati, K.; Knio, Omar; Maitre, O. Le

2017-01-01

Anomalous diffusion is a phenomenon that cannot be modeled accurately by second-order diffusion equations, but is better described by fractional diffusion models. The nonlocal nature of the fractional diffusion operators makes substantially more difficult the mathematical analysis of these models and the establishment of suitable numerical schemes. This paper proposes and analyzes the first finite difference method for solving {\\em variable-coefficient} fractional differential equations, with two-sided fractional derivatives, in one-dimensional space. The proposed scheme combines first-order forward and backward Euler methods for approximating the left-sided fractional derivative when the right-sided fractional derivative is approximated by two consecutive applications of the first-order backward Euler method. Our finite difference scheme reduces to the standard second-order central difference scheme in the absence of fractional derivatives. The existence and uniqueness of the solution for the proposed scheme are proved, and truncation errors of order $h$ are demonstrated, where $h$ denotes the maximum space step size. The numerical tests illustrate the global $O(h)$ accuracy of our scheme, except for nonsmooth cases which, as expected, have deteriorated convergence rates.

Foetal dose conversion coefficients for ICRP-compliant pregnant models from idealised proton exposures

International Nuclear Information System (INIS)

Taranenko, V.; Xu, X. G.

2009-01-01

Protection of pregnant women and their foetus against external proton irradiations poses a unique challenge. Assessment of foetal dose due to external protons in galactic cosmic rays and as secondaries generated in aircraft walls is especially important during high-altitude flights. This paper reports a set of fluence to absorbed dose conversion coefficients for the foetus and its brain for external monoenergetic proton beams of six standard configurations (the antero-posterior, the postero-anterior, the right lateral, the left lateral, the rotational and the isotropic). The pregnant female anatomical definitions at each of the three gestational periods (3, 6 and 9 months) are based on newly developed RPI-P series of models whose organ masses were matched within 1% with the International Commission on Radiological Protection reference values. Proton interactions and the transport of secondary particles were carefully simulated using the Monte Carlo N-Particle extended code (MCNPX) and the phantoms consisting of several million voxels at 3 mm resolution. When choosing the physics models in the MCNPX, it was found that the advanced Cascade-Exciton intranuclear cascade model showed a maximum of 9% foetal dose increase compared with the default model combination at intermediate energies below 5 GeV. Foetal dose results from this study are tabulated and compared with previously published data that were based on simplified anatomy. The comparison showed a strong dependence upon the source geometry, energy and gestation period: The dose differences are typically less than 20% for all sources except ISO where systematically 40-80% of higher doses were observed. Below 200 MeV, a larger discrepancy in dose was found due to the Bragg peak shift caused by different anatomy. The tabulated foetal doses represent the latest and most detailed study to date offering a useful set of data to improve radiation protection dosimetry against external protons. (authors)

Dependence of Seebeck coefficient on a load resistance and energy conversion efficiency in a thermoelectric composite

International Nuclear Information System (INIS)

Yamashita, Osamu; Odahara, Hirotaka; Ochi, Takahiro; Satou, Kouji

2007-01-01

The thermo-emf ΔV and current ΔI generated by imposing the alternating temperature gradients (ATG) at a period of T and the steady temperature gradient (STG) on a thermoelectric (TE) composite were measured as a function of t, where t is the lapsed time and T was varied from 60 to or ∞ s. The STG and ATG were produced by imposing steadily and alternatively a source voltage V in the range from 1.0 to 4.0 V on two Peltier modules sandwiching a composite. ΔT, ΔV, ΔI and V P oscillate at a period T and their waveforms vary significantly with a change of T, where ΔV and V P are the voltage drops in a load resistance R L and in resistance R P of two modules. The resultant Seebeck coefficient |α| = |ΔV|/ΔT of a composite under the STG was found to be expressed as |α| = |α 0 |(1 - R comp /R T ), where R T is the total resistance of a circuit for measuring the output signals and R comp is the resistance of a composite. The effective generating power ΔW eff has a local maximum at T = 960 s for the p-type composite and at T = 480 s for the n-type one. The maximum energy conversion efficiency η of the p- and n-type composites under the ATG produced by imposing a voltage of 4.0 V at an optimum period were 0.22 and 0.23% at ΔT eff = 50 K, respectively, which are 42 and 43% higher than those at ΔT = 42 K under the STG. These maximum η for a TE composite sandwiched between two Peltier modules, were found to be expressed theoretically in terms of R P , R T , R L , α P and α, where α P and α are the resultant Seebeck coefficients of Peltier modules and a TE composite

Improvement of dose evaluation system for employees at severe accident in a nuclear power plant. Introduction of the dose rate conversion coefficient and addition of the access route edit function

International Nuclear Information System (INIS)

Sasaki, Yasuhiro; Minami, Noritoshi; Yoshida, Yoshitaka

2006-01-01

Institute of Nuclear Safety System, Inc. had developed the dose evaluation system to evaluate the radiation dose of employees at severe accident in a nuclear power plant. This system has features, which are (1) the dose rate of any evaluation point can be evaluated, (2) the dose rate at any time can be evaluated in consideration of the change in the radioactive source, (3) the dose rate map in the plant can be displayed (4) the dose along the access route when moving can be evaluated, and it is possible to use it for examination of the accident management guideline on the dose side etc.. To upgrade the dose evaluation function of this system, the improvements had been done which were introduction of the dose rate conversion coefficient and addition of the access route edit function. By introducing the dose rate conversion coefficient, the calculation time of the dose rate map in the plant was shortened at about 20 seconds, and a new function to evaluate time-dependent dose rate of any evaluation point was added. By adding the access route edit function, it became possible to re-calculate the dose easily at the route change. (author)

Hydrogen photoproduction by photoelectrochemical conversion

International Nuclear Information System (INIS)

Anon.

1989-01-01

The water-splitting reaction by photoelectrochemical processes has gained much more attention than any of many reactions proposed for solar generation of energy-rich molecules (fuels). The conversion efficiency of the photosystem is the key factor. The higher the efficiency, the more economically feasible will be the conversion scheme. The conversion efficiency is a function of the semiconductor properties, light intensity, spectral quality, properties of the electrolyte, counterelectrode, cell configuration, etc. The semiconductor parameters include band gap, absorption coefficient and diffusion length. The area and material used for a counterelectrode are important when considering polarization losses in a two-electrode system. Besides, the stability problem is also a very important one to meet the requirement for practical applications. This paper reviews some important issues on photoelectrochemical generation of hydrogen by water splitting. It includes energy conversion efficiency, market assessment and cost goal, state of the technology, and future directions for research

Coupling between the differential and perturbation theory methods for calculating sensitivity coefficients in nuclear transmutation problems; Acoplamento entre os metodos diferencial e da teoria da perturbacao para o calculo dos coeficientes de sensibilidade em problemas de transmutacao nuclear

Energy Technology Data Exchange (ETDEWEB)

Rossi, Lubianka Ferrari Russo

2014-07-01

The main target of this study is to introduce a new method for calculating the coefficients of sensibility through the union of differential method and generalized perturbation theory, which are the two methods generally used in reactor physics to obtain such variables. These two methods, separated, have some issues turning the sensibility coefficients calculation slower or computationally exhaustive. However, putting them together, it is possible to repair these issues and build a new equation for the coefficient of sensibility. The method introduced in this study was applied in a PWR reactor, where it was performed the sensibility analysis for the production and {sup 239}Pu conversion rate during 120 days (1 cycle) of burnup. The computational code used for both burnup and sensibility analysis, the CINEW, was developed in this study and all the results were compared with codes widely used in reactor physics, such as CINDER and SERPENT. The new mathematical method for calculating the sensibility coefficients and the code CINEW provide good numerical agility and also good efficiency and security, once the new method, when compared with traditional ones, provide satisfactory results, even when the other methods use different mathematical approaches. The burnup analysis, performed using the code CINEW, was compared with the code CINDER, showing an acceptable variation, though CINDER presents some computational issues due to the period it was built. The originality of this study is the application of such method in problems involving temporal dependence and, not least, the elaboration of the first national code for burnup and sensitivity analysis. (author)

The conversion factor of α radiation efficiency

International Nuclear Information System (INIS)

Wang Weida; Zhou Zhixin; Xia Junding

1997-01-01

It is important in fine-grain TL dating that the full α dose must be converted into the equivalent β dose. Although the conversion coefficient K for internal radiation efficiency can not be measured directly for each sample, it is possible to measure the external radiation efficiency K 3.7 . For this purpose a special study for the conversion factor of K to K 3.7 has been made using ultrathin TLD. The results show that the conversion factor of the TLD for archaeological samples is 0.847, which is in agreement with the calculated value 0.85

Spectral theories for linear differential equations

International Nuclear Information System (INIS)

Sell, G.R.

1976-01-01

The use of spectral analysis in the study of linear differential equations with constant coefficients is not only a fundamental technique but also leads to far-reaching consequences in describing the qualitative behaviour of the solutions. The spectral analysis, via the Jordan canonical form, will not only lead to a representation theorem for a basis of solutions, but will also give a rather precise statement of the (exponential) growth rates of various solutions. Various attempts have been made to extend this analysis to linear differential equations with time-varying coefficients. The most complete such extensions is the Floquet theory for equations with periodic coefficients. For time-varying linear differential equations with aperiodic coefficients several authors have attempted to ''extend'' the Foquet theory. The precise meaning of such an extension is itself a problem, and we present here several attempts in this direction that are related to the general problem of extending the spectral analysis of equations with constant coefficients. The main purpose of this paper is to introduce some problems of current research. The primary problem we shall examine occurs in the context of linear differential equations with almost periodic coefficients. We call it ''the Floquet problem''. (author)

Apparent diffusion coefficient value of gastric cancer by diffusion-weighted imaging: Correlations with the histological differentiation and Lauren classification

International Nuclear Information System (INIS)

Liu, Song; Guan, Wenxian; Wang, Hao; Pan, Liang; Zhou, Zhuping; Yu, Haiping; Liu, Tian; Yang, Xiaofeng; He, Jian; Zhou, Zhengyang

2014-01-01

Highlights: • Gastric cancers’ ADC values were significantly lower than normal gastric wall. • Gastric adenocarcinomas with different differentiation had different ADC values. • Gastric adenocarcinomas’ ADC values correlated with histologic differentiations. • Gastric cancers’ ADC values correlated with Lauren classifications. • Mean ADC value was better than min ADC value in characterizing gastric cancers. - Abstract: Objective: The purpose of this study was to evaluate the correlations between histological differentiation and Lauren classification of gastric cancer and the apparent diffusion coefficient (ADC) value of diffusion weighted imaging (DWI). Materials and methods: Sixty-nine patients with gastric cancer lesions underwent preoperative magnetic resonance imaging (MRI) (3.0T) and surgical resection. DWI was obtained with a single-shot, echo-planar imaging sequence in the axial plane (b values: 0 and 1000 s/mm 2 ). Mean and minimum ADC values were obtained for each gastric cancer and normal gastric walls by two radiologists, who were blinded to the histological findings. Histological type, degree of differentiation and Lauren classification of each resected specimen were determined by one pathologist. Mean and minimum ADC values of gastric cancers with different histological types, degrees of differentiation and Lauren classifications were compared. Correlations between ADC values and histological differentiation and Lauren classification were analyzed. Results: The mean and minimum ADC values of gastric cancers, as a whole and separately, were significantly lower than those of normal gastric walls (all p values <0.001). There were significant differences in the mean and minimum ADC values among gastric cancers with different histological types, degrees of differentiation and Lauren classifications (p < 0.05). Mean and minimum ADC values correlated significantly (all p < 0.001) with histological differentiation (r = 0.564, 0.578) and Lauren

Recurrences and explicit formulae for the expansion and connection coefficients in series of Bessel polynomials

International Nuclear Information System (INIS)

Doha, E H; Ahmed, H M

2004-01-01

A formula expressing explicitly the derivatives of Bessel polynomials of any degree and for any order in terms of the Bessel polynomials themselves is proved. Another explicit formula, which expresses the Bessel expansion coefficients of a general-order derivative of an infinitely differentiable function in terms of its original Bessel coefficients, is also given. A formula for the Bessel coefficients of the moments of one single Bessel polynomial of certain degree is proved. A formula for the Bessel coefficients of the moments of a general-order derivative of an infinitely differentiable function in terms of its Bessel coefficients is also obtained. Application of these formulae for solving ordinary differential equations with varying coefficients, by reducing them to recurrence relations in the expansion coefficients of the solution, is explained. An algebraic symbolic approach (using Mathematica) in order to build and solve recursively for the connection coefficients between Bessel-Bessel polynomials is described. An explicit formula for these coefficients between Jacobi and Bessel polynomials is given, of which the ultraspherical polynomial and its consequences are important special cases. Two analytical formulae for the connection coefficients between Laguerre-Bessel and Hermite-Bessel are also developed

Measurement of conversion coefficients between air Kerma and personal dose equivalent and backscatter factors for diagnostic X-ray beams; Determinacao experimental dos coeficientes de conversao de Kerma no ar para o equivalente de dose pessoal, Hp(d), e fatores de retroespalhamento em feixes de raios-x diagnostico

Energy Technology Data Exchange (ETDEWEB)

Rosado, Paulo Henrique Goncalves

2008-07-01

Two sets of quantities are import in radiological protection: the protection and operational quantities. Both sets can be related to basic physical quantities such as kerma through conversion coefficients. For diagnostic x-ray beams the conversion coefficients and backscatter factors have not been determined yet, those parameters are need for calibrating dosimeters that will be used to determine the personal dose equivalent or the entrance skin dose. Conversion coefficients between air kerma and personal dose equivalent and backscatter factors were experimentally determined for the diagnostic x-ray qualities RQR and RQA recommended by the International Electrotechnical Commission (IEC). The air kerma in the phantom and the mean energy of the spectrum were measured for such purpose. Harshaw LiF-100H thermoluminescent dosemeters (TLD) were used for measurements after being calibrated against an 180 cm{sup 3} Radcal Corporation ionization chamber traceable to a reference laboratory. A 300 mm x 300 mm x 150 mm polymethylmethacrylate (PMMA) slab phantom was used for deep-dose measurements. Tl dosemeters were placed in the central axis of the x-ray beam at 5, 10, 15, 25 and 35 mm depth in the phantom upstream the beam direction Another required parameter for determining the conversion coefficients from was the mean energy of the x-ray spectrum. The spectroscopy of x-ray beams was done with a CdTe semiconductor detector that was calibrated with {sup 133} Ba, {sup 241} Am and {sup 57} Co radiation sources. Measurements of the x-ray spectra were carried out for all RQR and RQA IEC qualities. Corrections due to the detector intrinsic efficiency, total energy absorption, escape fraction of the characteristic x-rays, Compton effect and attenuation in the detector were done aiming an the accurate determination of the mean energy. Measured x-ray spectra were corrected with the stripping method by using these response functions. The typical combined standard uncertainties of

Diffusion weighted imaging for differentiating benign from malignant orbital tumors: Diagnostic performance of the apparent diffusion coefficient based on region of interest selection method

Energy Technology Data Exchange (ETDEWEB)

Xu, Xiao Quan; Hu, Hao Hu; Su, Guo Yi; Liu, Hu; Shi, Hai Bin; Wu, Fei Yun [First Affiliated Hospital of Nanjing Medical University, Nanjing (China)

2016-09-15

To evaluate the differences in the apparent diffusion coefficient (ADC) measurements based on three different region of interest (ROI) selection methods, and compare their diagnostic performance in differentiating benign from malignant orbital tumors. Diffusion-weighted imaging data of sixty-four patients with orbital tumors (33 benign and 31 malignant) were retrospectively analyzed. Two readers independently measured the ADC values using three different ROIs selection methods including whole-tumor (WT), single-slice (SS), and reader-defined small sample (RDSS). The differences of ADC values (ADC-ROI{sub WT}, ADC-ROI{sub SS}, and ADC-ROI{sub RDSS}) between benign and malignant group were compared using unpaired t test. Receiver operating characteristic curve was used to determine and compare their diagnostic ability. The ADC measurement time was compared using ANOVA analysis and the measurement reproducibility was assessed using Bland-Altman method and intra-class correlation coefficient (ICC). Malignant group showed significantly lower ADC-ROI{sub WT}, ADC-ROI{sub SS}, and ADC-ROI{sub RDSS} than benign group (all p < 0.05). The areas under the curve showed no significant difference when using ADC-ROI{sub WT}, ADC-ROI{sub SS}, and ADC-ROI{sub RDSS} as differentiating index, respectively (all p > 0.05). The ROI{sub SS} and ROI{sub RDSS} required comparable measurement time (p > 0.05), while significantly shorter than ROI{sub WT} (p < 0.05). The ROI{sub SS} showed the best reproducibility (mean difference ± limits of agreement between two readers were 0.022 [-0.080–0.123] × 10{sup -3} mm{sup 2}/s; ICC, 0.997) among three ROI method. Apparent diffusion coefficient values based on the three different ROI selection methods can help to differentiate benign from malignant orbital tumors. The results of measurement time, reproducibility and diagnostic ability suggest that the ROI{sub SS} method are potentially useful for clinical practice.

The measurement of internal conversion electrons of selected nuclei: A physics undergraduate laboratory experience

International Nuclear Information System (INIS)

Nagy, P.; Duggan, J.L.; Desmarais, D.

1992-01-01

Thin sources are now commercially available for a wide variety of isotopes that have measurable internal conversion coefficients. The authors have used standard surface barrier detectors, NIM electronics, and a personal computer analyzer to measure conversion electrons from a few of these sources. Conversion electrons energy and intensity were measured for 113 Sn, 133 Ba, 137 Cs, and 207 Bi. From the measured spectra the innershell binding energies of the K ampersand L Shell electrons from the daughter nuclei were determined and compared to theory. The relative conversion coefficients a k /a L and the K/L ration were also measured. The spin and parity change of the transitions will also be assigned based on the selection rules of the transitions

Primary central nervous system lymphoma and atypical glioblastoma: differentiation using the initial area under the curve derived from dynamic contrast-enhanced MR and the apparent diffusion coefficient

International Nuclear Information System (INIS)

Choi, Yoon Seong; Lee, Ho-Joon; Ahn, Sung Soo; Lee, Seung-Koo; Chang, Jong Hee; Kang, Seok-Gu; Kim, Eui Hyun; Kim, Se Hoon

2017-01-01

To evaluate the ability of the initial area under the curve (IAUC) derived from dynamic contrast-enhanced MR imaging (DCE-MRI) and apparent diffusion coefficient (ADC) in differentiating between primary central nervous system lymphoma (PCNSL) and atypical glioblastoma (GBM). We retrospectively identified 19 patients with atypical GBM (less than 13 % necrosis of the enhancing tumour), and 23 patients with PCNSL. The histogram parameters of IAUC at 30, 60, 90 s (IAUC30, IAUC60, and IAUC90), and ADC were compared between PCNSL and GBM. The diagnostic performances and added values of the IAUC and ADC for differentiating between PCNSL and GBM were evaluated. Interobserver agreement was assessed via intraclass correlation coefficient (ICC). The IAUC and ADC parameters were higher in GBM than in PCNSL. The 90th percentile (p90) of IAUC30 and 10th percentile (p10) of ADC showed the best diagnostic performance. Adding p90 of IAUC30 to p10 of ADC improved the differentiation between PCNSL and GBM (area under the ROC curve [AUC] = 0.886), compared to IAUC30 or ADC alone (AUC = 0.789 and 0.744; P < 0.05 for all). The ICC was 0.96 for p90 of IAUC30. The IAUC may be a useful parameter together with ADC for differentiating between PCNSL and atypical GBM. (orig.)

Primary central nervous system lymphoma and atypical glioblastoma: differentiation using the initial area under the curve derived from dynamic contrast-enhanced MR and the apparent diffusion coefficient

Energy Technology Data Exchange (ETDEWEB)

Choi, Yoon Seong; Lee, Ho-Joon; Ahn, Sung Soo; Lee, Seung-Koo [Yonsei University College of Medicine, Department of Radiology and Research Institute of Radiological Science, Seodaemun-gu, Seoul (Korea, Republic of); Chang, Jong Hee; Kang, Seok-Gu; Kim, Eui Hyun [Yonsei University College of Medicine, Department of Neurosurgery, Seoul (Korea, Republic of); Kim, Se Hoon [Yonsei University College of Medicine, Department of Pathology, Seoul (Korea, Republic of)

2017-04-15

To evaluate the ability of the initial area under the curve (IAUC) derived from dynamic contrast-enhanced MR imaging (DCE-MRI) and apparent diffusion coefficient (ADC) in differentiating between primary central nervous system lymphoma (PCNSL) and atypical glioblastoma (GBM). We retrospectively identified 19 patients with atypical GBM (less than 13 % necrosis of the enhancing tumour), and 23 patients with PCNSL. The histogram parameters of IAUC at 30, 60, 90 s (IAUC30, IAUC60, and IAUC90), and ADC were compared between PCNSL and GBM. The diagnostic performances and added values of the IAUC and ADC for differentiating between PCNSL and GBM were evaluated. Interobserver agreement was assessed via intraclass correlation coefficient (ICC). The IAUC and ADC parameters were higher in GBM than in PCNSL. The 90th percentile (p90) of IAUC30 and 10th percentile (p10) of ADC showed the best diagnostic performance. Adding p90 of IAUC30 to p10 of ADC improved the differentiation between PCNSL and GBM (area under the ROC curve [AUC] = 0.886), compared to IAUC30 or ADC alone (AUC = 0.789 and 0.744; P < 0.05 for all). The ICC was 0.96 for p90 of IAUC30. The IAUC may be a useful parameter together with ADC for differentiating between PCNSL and atypical GBM. (orig.)

Fluence-to-dose conversion coefficients based on the posture modification of Adult Male (AM) and Adult Female (AF) reference phantoms of ICRP 110

International Nuclear Information System (INIS)

Galeano, D.C.; Santos, W.S.; Alves, M.C.; Souza, D.N.; Carvalho, A.B.

2016-01-01

The aim of this work was to modify the standing posture of the anthropomorphic reference phantoms of ICRP publication 110, AM (Adult Male) and AF (Adult Female), to the sitting posture. The change of posture was performed using the Visual Monte Carlo software (VMC) to rotate the thigh region of the phantoms and position it between the region of the leg and trunk. Scion Image software was used to reconstruct and smooth the knee and hip contours of the phantoms in a sitting posture. For 3D visualization of phantoms, the VolView software was used. In the change of postures, the organ and tissue masses were preserved. The MCNPX was used to calculate the equivalent and effective dose conversion coefficients (CCs) per fluence for photons for six irradiation geometries suggested by ICRP publication 110 (AP, PA, RLAT, LLAT, ROT and ISO) and energy range 0.010–10 MeV. The results were compared between the standing and sitting postures, for both sexes, in order to evaluate the differences of scattering and absorption of radiation for different postures. Significant differences in the CCs for equivalent dose were observed in the gonads, colon, prostate, urinary bladder and uterus, which are present in the pelvic region, and in organs distributed throughout the body, such as the lymphatic nodes, muscle, skeleton and skin, for the phantoms of both sexes. CCs for effective dose showed significant differences of up to 16% in the AP irradiation geometry, 27% in the PA irradiation geometry and 13% in the ROT irradiation geometry. These results demonstrate the importance of using phantoms in different postures in order to obtain more precise conversion coefficients for a given exposure scenario. - Highlights: • The reference phantoms AM and AF had modified its posture. • The AM and AF phantoms were irradiated in standing and sitting postures. • The irradiation geometry used were the AP, PA, LLAT, RLAT, ROT and ISO. • The CCs for standing and sitting postures were compared

Calculating differential Galois groups of parametrized differential equations, with applications to hypertranscendence

OpenAIRE

Hardouin, Charlotte; Minchenko, Andrei; Ovchinnikov, Alexey

2015-01-01

The main motivation of our work is to create an efficient algorithm that decides hypertranscendence of solutions of linear differential equations, via the parameterized differential and Galois theories. To achieve this, we expand the representation theory of linear differential algebraic groups and develop new algorithms that calculate unipotent radicals of parameterized differential Galois groups for differential equations whose coefficients are rational functions. P. Berman and M.F. Singer ...

Conversion of electromagnetic waves at the ionisation front

International Nuclear Information System (INIS)

Chegotov, M V

2001-01-01

It is shown that a weak electromagnetic pulse interacting with a copropagating ionisation front is converted in the general case into three electromagnetic pulses with higher and lower frequencies, which propagate in different directions. The coefficients of conversion to these pulses (for intensities) were found as functions of the frequency. The electromagnetic energy is shown to decrease during this conversion because of the losses for the residual electron energy. (interaction of laser radiation with matter. laser plasma)

On the conversion of dose to bone to dose to water in radiotherapy treatment planning systems

Directory of Open Access Journals (Sweden)

Nick Reynaert

2018-01-01

Full Text Available Background and purpose: Conversion factors between dose to medium (Dm,m and dose to water (Dw,w provided by treatment planning systems that model the patient as water with variable electron density are currently based on stopping power ratios. In the current paper it will be illustrated that this conversion method is not correct. Materials and methods: Monte Carlo calculations were performed in a phantom consisting of a 2 cm bone layer surrounded by water. Dw,w was obtained by modelling the bone layer as water with the electron density of bone. Conversion factors between Dw,w and Dm,m were obtained and compared to stopping power ratios and ratios of mass-energy absorption coefficients in regions of electronic equilibrium and interfaces. Calculations were performed for 6 MV and 20 MV photon beams. Results: In the region of electronic equilibrium the stopping power ratio of water to bone (1.11 largely overestimates the conversion obtained using the Monte Carlo calculations (1.06. In that region the MC dose conversion corresponds to the ratio of mass energy absorption coefficients. Near the water to bone interface, the MC ratio cannot be determined from stopping powers or mass energy absorption coefficients. Conclusion: Stopping power ratios cannot be used for conversion from Dm,m to Dw,w provided by treatment planning systems that model the patient as water with variable electron density, either in regions of electronic equilibrium or near interfaces. In regions of electronic equilibrium mass energy absorption coefficient ratios should be used. Conversions at interfaces require detailed MC calculations. Keywords: Dose to water, Monte Carlo, Dosimetry, TPS comparison

Roughness coefficient and its uncertainty in gravel-bed river

Directory of Open Access Journals (Sweden)

Ji-Sung Kim

2010-06-01

Full Text Available Manning's roughness coefficient was estimated for a gravel-bed river reach using field measurements of water level and discharge, and the applicability of various methods used for estimation of the roughness coefficient was evaluated. Results show that the roughness coefficient tends to decrease with increasing discharge and water depth, and over a certain range it appears to remain constant. Comparison of roughness coefficients calculated by field measurement data with those estimated by other methods shows that, although the field-measured values provide approximate roughness coefficients for relatively large discharge, there seems to be rather high uncertainty due to the difference in resultant values. For this reason, uncertainty related to the roughness coefficient was analyzed in terms of change in computed variables. On average, a 20% increase of the roughness coefficient causes a 7% increase in the water depth and an 8% decrease in velocity, but there may be about a 15% increase in the water depth and an equivalent decrease in velocity for certain cross-sections in the study reach. Finally, the validity of estimated roughness coefficient based on field measurements was examined. A 10% error in discharge measurement may lead to more than 10% uncertainty in roughness coefficient estimation, but corresponding uncertainty in computed water depth and velocity is reduced to approximately 5%. Conversely, the necessity for roughness coefficient estimation by field measurement is confirmed.

A new methodology for determining dispersion coefficient using ordinary and partial differential transport equations.

Science.gov (United States)

Cho, Kyung Hwa; Lee, Seungwon; Ham, Young Sik; Hwang, Jin Hwan; Cha, Sung Min; Park, Yongeun; Kim, Joon Ha

2009-01-01

The present study proposes a methodology for determining the effective dispersion coefficient based on the field measurements performed in Gwangju (GJ) Creek in South Korea which is environmentally degraded by the artificial interferences such as weirs and culverts. Many previous works determining the dispersion coefficient were limited in application due to the complexity and artificial interferences in natural stream. Therefore, the sequential combination of N-Tank-In-Series (NTIS) model and Advection-Dispersion-Reaction (ADR) model was proposed for evaluating dispersion process in complex stream channel in this study. The series of water quality data were intensively monitored in the field to determine the effective dispersion coefficient of E. coli in rainy day. As a result, the suggested methodology reasonably estimates the dispersion coefficient for GJ Creek with 1.25 m(2)/s. Also, the sequential combined method provided Number of tank-Velocity-Dispersion coefficient (NVD) curves for convenient evaluation of dispersion coefficient of other rivers or streams. Comparing the previous studies, the present methodology is quite general and simple for determining the effective dispersion coefficients which are applicable for other rivers and streams.

Restricted mass energy absorption coefficients for use in dosimetry

International Nuclear Information System (INIS)

Brahme, A.

1977-02-01

When matter is irradiated by a photon beam the fraction of energy absorbed locally in some region Rsub(Δ) (where the size of the region Rsub(Δ) is related to the range of secondary electrons of some restriction energy Δ) is expressed by the restricted mass energy absorption coefficient. In this paper an example is given of how restricted mass energy absorption coefficients can be calculated from existing differential photon interaction cross sections. Some applications of restricted mass absorption coefficients in dosimetry are also given. (B.D.)

Control in the coefficients with variational crimes

DEFF Research Database (Denmark)

Evgrafov, Anton; Marhadi, Kun Saptohartyadi

2012-01-01

We study convergence of discontinuous Galerkin-type discretizations of the problems of control in the coefficients of uniformly elliptic partial differential equations (PDEs). As a model problem we use that of the optimal design of thin (Kirchhoff) plates, where the governing equations...

Radiological indeterminate vestibular schwannoma and meningioma in cerebellopontine angle area: differentiating using whole-tumor histogram analysis of apparent diffusion coefficient.

Science.gov (United States)

Xu, Xiao-Quan; Li, Yan; Hong, Xun-Ning; Wu, Fei-Yun; Shi, Hai-Bin

2017-02-01

To assess the role of whole-tumor histogram analysis of apparent diffusion coefficient (ADC) maps in differentiating radiological indeterminate vestibular schwannoma (VS) from meningioma in cerebellopontine angle (CPA). Diffusion-weighted (DW) images (b = 0 and 1000 s/mm 2 ) of pathologically confirmed and radiological indeterminate CPA meningioma (CPAM) (n = 27) and VS (n = 12) were retrospectively collected and processed with mono-exponential model. Whole-tumor regions of interest were drawn on all slices of the ADC maps to obtain histogram parameters, including the mean ADC (ADC mean ), median ADC (ADC median ), 10th/25th/75th/90th percentile ADC (ADC 10 , ADC 25 , ADC 75 and ADC 90 ), skewness and kurtosis. The differences of ADC histogram parameters between CPAM and VS were compared using unpaired t-test. Multiple receiver operating characteristic (ROC) curves analysis was used to determine and compare the diagnostic value of each significant parameter. Significant differences were found on the ADC mean , ADC median , ADC 10 , ADC 25 , ADC 75 and ADC 90 between CPAM and VS (all p values Histogram analysis of ADC maps based on whole tumor can be a useful tool for differentiating radiological indeterminate CPAM from VS. The ADC 90 value was the most promising parameter for differentiating these two entities.

Fluence-to-absorbed-dose conversion coefficients for neutron beams from 0.001 eV to 100 GeV calculated for a set of pregnant female and fetus models

International Nuclear Information System (INIS)

Taranenko, Valery; Xu, X George

2008-01-01

Protection of fetuses against external neutron exposure is an important task. This paper reports a set of absorbed dose conversion coefficients for fetal and maternal organs for external neutron beams using the RPI-P pregnant female models and the MCNPX code. The newly developed pregnant female models represent an adult female with a fetus including its brain and skeleton at the end of each trimester. The organ masses were adjusted to match the reference values within 1%. For the 3 mm cubic voxel size, the models consist of 10-15 million voxels for 35 organs. External monoenergetic neutron beams of six standard configurations (AP, PA, LLAT, RLAT, ROT and ISO) and source energies 0.001 eV-100 GeV were considered. The results are compared with previous data that are based on simplified anatomical models. The differences in dose depend on source geometry, energy and gestation periods: from 20% up to 140% for the whole fetus, and up to 100% for the fetal brain. Anatomical differences are primarily responsible for the discrepancies in the organ doses. For the first time, the dependence of mother organ doses upon anatomical changes during pregnancy was studied. A maximum of 220% increase in dose was observed for the placenta in the nine months model compared to three months, whereas dose to the pancreas, small and large intestines decreases by 60% for the AP source for the same models. Tabulated dose conversion coefficients for the fetus and 27 maternal organs are provided

Deuterons at energies of 10 MeV to 1 TeV: Conversion coefficients for fluence-to-absorbed dose, equivalent dose, effective dose and gray equivalent, calculated using Monte Carlo radiation transport code MCNPX 2.7.C

International Nuclear Information System (INIS)

Copeland, K.; Parker, D. E.; Friedberg, W.

2011-01-01

Conversion coefficients were calculated for fluence-to-absorbed dose, fluence-to-equivalent dose, fluence-to-effective dose and fluence-to-gray equivalent for isotropic exposure of an adult female and an adult male to deuterons ( 2 H + ) in the energy range 10 MeV -1 TeV (0.01-1000 GeV). Coefficients were calculated using the Monte Carlo transport code MCNPX 2.7.C and BodyBuilder TM 1.3 anthropomorphic phantoms. Phantoms were modified to allow calculation of the effective dose to a Reference Person using tissues and tissue weighting factors from 1990 and 2007 recommendations of the International Commission on Radiological Protection (ICRP) and gray equivalent to selected tissues as recommended by the National Council on Radiation Protection and Measurements. Coefficients for the equivalent and effective dose incorporated a radiation weighting factor of 2. At 15 of 19 energies for which coefficients for the effective dose were calculated, coefficients based on ICRP 1990 and 2007 recommendations differed by < 3 %. The greatest difference, 47 %, occurred at 30 MeV. (authors)

Development of a cell culture surface conversion technique using alginate thin film for evaluating effect upon cellular differentiation

International Nuclear Information System (INIS)

Nakashima, Y.; Tsusu, K.; Minami, K.; Nakanishi, Y.

2014-01-01

Here, we sought to develop a cell culture surface conversion technique that would not damage living cells. An alginate thin film, formed on a glass plate by spin coating of sodium alginate solution and dipping into calcium chloride solution, was used to inhibit adhesion of cells. The film could be removed by ethylenediaminetetraacetate (EDTA) at any time during cell culture, permitting observation of cellular responses to conversion of the culture surface in real time. Additionally, we demonstrated the validity of the alginate thin film coating method and the performance of the film. The thickness of the alginate thin film was controlled by varying the rotation speed during spin coating. Moreover, the alginate thin film completely inhibited the adhesion of cultured cells to the culture surface, irrespective of the thickness of the film. When the alginate thin film was removed from the culture surface by EDTA, the cultured cells adhered to the culture surface, and their morphology changed. Finally, we achieved effective differentiation of C2C12 myoblasts into myotube cells by cell culture on the convertible culture surface, demonstrating the utility of our novel technique

Extraction of Dunham coefficients from Murrell-Sorbie parameters

International Nuclear Information System (INIS)

Lim Teikcheng

2008-01-01

A set of relationships between parameters of the Dunham and Murrell-Sorbie potential energy function is developed. By employing Taylor series expansion and comparison of terms arranged in increasing order of bond length, a set of Dunham coefficients is obtained as functions of Murrell- Sorbie parameters. The conversion functions reveal the importance of factorials in extracting Dunham coefficients from Murrell-Sorbie parameters. Plots of both functions, based on parameters of the latter, reveal good correlation near the equilibrium bond length for a group of diatomic molecules. Potential function relations, such as that shown in this paper, are useful when the preferred/reliable data is based on a potential function different from that adopted in available computational software. (orig.)

Seeley-Gilkey coefficients for fourth-order operators on Riemannian manifold

International Nuclear Information System (INIS)

Gusynin, V.P.

1990-01-01

The covariant pseudodifferential-operator method of Widom is developed for computing the coefficients in the heat kernel expansion. It allows one to calculate Seeley-Gilkey coefficients for both minimal and nonminimal differential operators acting on a vector bundle over a riemannian manifold. The coefficients for the fourth-order minimal operators in arbitrary dimensions of space are calculated. In contrast to the second-order operators the coefficients for the fourth-order (and higher) operators turn out to be essentially dependent on the space dimension. The algorithmic character of the method allows one to calculate the coefficients by computer using an analytical calculation system. The method also permits a simple generalization to manifolds with torsion and supermanifolds. (orig.)

Evaluation of the fluence to dose conversion coefficients for high energy neutrons using a voxel phantom coupled with the GEANT4 code

CERN Document Server

Paganini, S

2005-01-01

Crews working on present-day jet aircraft are a large occupationally exposed group with a relatively high average effective dose from Galactic cosmic radiation. Crews of future high-speed commercial flying at higher altitudes would be even more exposed. To help reduce the significant uncertainties in calculations of such exposures, the male adult voxels phantom MAX, developed in the Nuclear Energy Department of Pernambuco Federal University in Brazil, has been coupled with the Monte Carlo simulation code GEANT4. This toolkit, distributed and upgraded from the international scientific community of CERN/Switzerland, simulates thermal to ultrahigh energy neutrons transport and interactions in the matter. The high energy neutrons are pointed as the component that contribute about 70% of the neutron effective dose that represent the 35% to 60% total dose at aircraft altitude. In this research calculations of conversion coefficients from fluence to effective dose are performed for neutrons of energies from 100 MeV ...

The role of apparent diffusion coefficient in the differentiation between benign and malignant bone tumors

International Nuclear Information System (INIS)

Liu Jicun; Cui Jianling; Li Shiling; Guo Zhiping; Ma Xiaohui

2009-01-01

Objective: To explore the role of apparent diffusion coefficient (ADC) value of diffusion-weighted imaging (DWI) in the differentiation between benign and malignant bone tumors. Methods: Echo planar imaging DWI was performed in 18 patients with benign tumor or tumorous lesion and 26 patients with malignant tumor of bone. Three b-values (0, 500 and 1000 s/mm 2 ) were applied. The lowest, highest, and whole ADC values were measured for each lesion, respectively. Results: The lowest ADC values of benign bone tumor [mean (1.28 ± 0.49)x10 -3 mm 2 /s] were significantly higher than that of malignant tumor [ mean (0.92 ± 0.35) x10 -3 mm 2 /s,t =2.839,P -3 mm 2 /s] were significantly higher than that of malignant tumor [ mean (1.21 ± 0.36)x10 -3 mm 2 /s, t =3.092, P -3 mm 2 /s] and malignant bone tumor [ mean (1.71 ± 0.65)x10 -3 mm 2 /s, t = 1.669, P > 0.05]. Excluding cases of bone cyst and aneurismal bone cyst, the lowest, highest, and whole ADC values of benign bone tumor waw (1.11 ± 0.31)x10 -3 mm 2 /s, (1.88 ± 0.49)x10 -3 mm 2 /s, and (1.45 ± 0.35)x10 -3 mm 2 /s, respectively. There was no significant difference for the lowest, highest, or whole ADC values between benign and malignant bone tumor (t =1.728, 0.964, and 2.012, respectively, P> 0.05). Conclusion: ADC value is useless for the differentiation between benign and malignant bone tumors. (authors)

Modular approach for conversion to the ion-hybrid wave and α gyroresonance

International Nuclear Information System (INIS)

Kaufman, A.N.; Morehead, J.J.; Brizard, A.J.; Tracy, E.R.

1997-01-01

Linear conversion of an incoming magnetosonic wave (a.k.a. fast or compressional wave) to an ion-hybrid wave can be considered as a 3-step process in ray phase space. This is demonstrated by casting the cold-fluid model into the Friedland-Kaufman normal form for linear mode conversion. First, the incoming magnetosonic ray (MSR) converts a fraction of its action to an intermediate ion-hybrid ray (IHR), with the transmitted ray proceeding through the conversion layer. The IHR propagates in k-space to a second conversion point, where it converts in turn a fraction of its action into a reflected MSR, with the remainder of the its action constituting the converted IHR. The modular approach gives exact agreement with the more standard Budden formulation for the transmission, reflection and conversion coefficients, but has the important advantage of exposing the intermediate IHR. The existence of the intermediate IHR has important physical consequences as it can resonate with α particles. We estimate the time-integrated damping coefficient between the two conversions and show that ∫γdt is of order -100, thus the IH wave is completely annihilated between conversions and transfers its energy to the α close-quote s. This suggests that proposals to use the IH mode for current drive or DT heating are likely to fail in the presence of fusion α close-quote s. copyright 1997 American Institute of Physics

Improved differentiation between hepatic hemangioma and metastases on diffusion-weighted MRI by measurement of standard deviation of apparent diffusion coefficient.

Science.gov (United States)

Hardie, Andrew D; Egbert, Robert E; Rissing, Michael S

2015-01-01

Diffusion-weighted magnetic resonance imaging (DW-MR) can be useful in the differentiation of hemangiomata from liver metastasis, but improved methods other than by mean apparent diffusion coefficient (mADC) are needed. A retrospective review identified 109 metastatic liver lesions and 86 hemangiomata in 128 patients who had undergone DW-MR. For each lesion, mADC and the standard deviation of the mean ADC (sdADC) were recorded and compared by receiver operating characteristic analysis. Mean mADC was higher in benign hemangiomata (1.52±0.12 mm(2)/s) than in liver metastases (1.33±0.18 mm(2)/s), but there was significant overlap in values. The mean sdADC was lower in hemangiomata (101±17 mm(2)/s) than metastases (245±25 mm(2)/s) and demonstrated no overlap in values, which was significantly different (P<.0001). Hemangiomata may be better able to be differentiated from liver metastases on the basis of sdADC than by mADC, although further studies are needed. Copyright © 2015 Elsevier Inc. All rights reserved.

Photon - axion conversions in a periodic electromagnetic field with axion frequency

International Nuclear Information System (INIS)

Dang Van Soa

1998-09-01

The conversion of photons into axions in a periodic external electromagnetic field with axion frequency is considered in detail by Feynman methods. The differential cross sections are given. It is shown that there is a resonant conversion for the considered process. (author)

Analytical solution for the mode conversion equations with steep exponential density profiles

International Nuclear Information System (INIS)

Alava, M.J.; Heikkinen, J.A.

1992-01-01

A general analytical solution for the converted power from the fast magnetosonic wave to an ion Bernstein wave in a magnetized plasma with an exponential steeply increasing density profile is given in the closed form. The solution covers both the conversion at the lower-hybrid resonance and the conversion through the density gradient for small parallel wave numbers. As an application, the conversion coefficients at the scrape-off layer plasma are estimated in the context of ion cyclotron heating of a tokamak plasma

Measurement and prediction of aromatic solute distribution coefficients for aqueous-organic solvent systems. Final report

Energy Technology Data Exchange (ETDEWEB)

Campbell, J.R.; Luthy, R.G.

1984-06-01

Experimental and modeling activities were performed to assess techniques for measurement and prediction of distribution coefficients for aromatic solutes between water and immiscible organic solvents. Experiments were performed to measure distribution coefficients in both clean water and wastewater systems, and to assess treatment of a wastewater by solvent extraction. The theoretical portions of this investigation were directed towards development of techniques for prediction of solute-solvent/water distribution coefficients. Experiments were performed to assess treatment of a phenolic-laden coal conversion wastewater by solvent extraction. The results showed that solvent extraction for recovery of phenolic material offered several wastewater processing advantages. Distribution coefficients were measured in clean water and wastewater systems for aromatic solutes of varying functionality with different solvent types. It was found that distribution coefficients for these compounds in clean water systems were not statistically different from distribution coefficients determined in a complex coal conversion process wastewater. These and other aromatic solute distribution coefficient data were employed for evaluation of modeling techniques for prediction of solute-solvent/water distribution coefficients. Eight solvents were selected in order to represent various chemical classes: toluene and benzene (aromatics), hexane and heptane (alkanes), n-octanol (alcohols), n-butyl acetate (esters), diisopropyl ether (ethers), and methylisobutyl ketone (ketones). The aromatic solutes included: nonpolar compounds such as benzene, toluene and naphthalene, phenolic compounds such as phenol, cresol and catechol, nitrogenous aromatics such as aniline, pyridine and aminonaphthalene, and other aromatic solutes such as naphthol, quinolinol and halogenated compounds. 100 references, 20 figures, 34 tables.

Converse flexoelectric effect in comb electrode piezoelectric microbeam

Energy Technology Data Exchange (ETDEWEB)

Shen, Zhiyuan, E-mail: shenyuan675603@gmail.com [School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore (Singapore); Chen, Wei [Microelectronics Centre, School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore (Singapore)

2012-04-09

We demonstrate the converse flexoelectric effect in a lead zirconate titanate microbeam. The fringe electric field of a comb electrode induces converse flexoelectric responses in uniformly poled and depoled beams. The simulated electric field distribution shows that bending of the beam is induced by piezoelectric and μ{sub 11}, μ{sub 12} flexoelectric coefficients. Simulations indicate that piezoelectric displacement occurs in different directions in the two opposite poled samples while flexoelectric displacement remains the same. This finding is verified by the displacement measurement results. -- Highlights: ► We demonstrate the converse flexoelectric effect in a PZT microbeam. ► Beams with upward and downward poling states are fabricated by MEMS technique. ► Converse flexoelectric deformation is induced by the fringe field. ► Electric field distribution is calculated by finite element analysis. ► The simulation results are verified by impedance and displacement measurements.

Role of apparent diffusion coefficients with diffusion-weighted magnetic resonance imaging in differentiating between benign and malignant bone tumors.

Science.gov (United States)

Wang, Tingting; Wu, Xiangru; Cui, Yanfen; Chu, Caiting; Ren, Gang; Li, Wenhua

2014-11-29

Benign and malignant bone tumors can present similar imaging features. This study aims to evaluate the significance of apparent diffusion coefficients (ADC) in differentiating between benign and malignant bone tumors. A total of 187 patients with 198 bone masses underwent diffusion-weighted (DW) magnetic resonance (MR) imaging. The ADC values in the solid components of the bone masses were assessed. Statistical differences between the mean ADC values in the different tumor types were determined by Student's t-test. Histological analysis showed that 84/198 (42.4%) of the bone masses were benign and 114/198 (57.6%) were malignant. There was a significant difference between the mean ADC values in the benign and malignant bone lesions (Pbenign and malignant bone tumors.

Exact solutions to a nonlinear dispersive model with variable coefficients

International Nuclear Information System (INIS)

Yin Jun; Lai Shaoyong; Qing Yin

2009-01-01

A mathematical technique based on an auxiliary differential equation and the symbolic computation system Maple is employed to investigate a prototypical and nonlinear K(n, n) equation with variable coefficients. The exact solutions to the equation are constructed analytically under various circumstances. It is shown that the variable coefficients and the exponent appearing in the equation determine the quantitative change in the physical structures of the solutions.

A software to edit voxel phantoms and to calculate conversion coefficients for radiation protection

International Nuclear Information System (INIS)

Vieira, J.W.; Stosic, B.; Lima, F.R.A.; Kramer, R.; Santos, A.M.; Lima, V.J.M.

2005-01-01

The MAX and FAX phantoms have been developed based on a male and female, respectively, adult body from ICRP and coupled to the Monte Carlo code (EGS4). These phantoms permit the calculating of the equivalent dose in organs and tissues of the human body for the radiation protection purposes . In the constructing of these anthropomorphic models, the software developed called FANTOMAS, which performs tasks as file format conversion, filtering 2D and 3D images, exchange of identifying numbers of organs, body mass adjustments based in volume, resampling of 2D and 3D images, resize images, preview consecutive slices of the phantom, running computational models of exposure FANTOMA/EGS4 and viewing graphics of conversion factors between equivalent dose and a measurable dosimetric quantity. This paper presents the main abilities of FANTOMAS and uses the MAX and/or FAX to exemplify some procedures

Photon - axion conversion cross sections in an electromagnetic field

International Nuclear Information System (INIS)

Dang Van Soa; Ha Huy Bang

1999-12-01

Photon - axion conversions in static magnetic fields and in a periodic field with frequency equal to the axion mass are reconsidered in detail by Feynman methods. The differential cross sections are presented and numerical evaluations are given. It is shown that there is a resonant conversion for the considered process. Some estimates for experiments are given from our results. (author)

Exact Finite-Difference Schemes for d-Dimensional Linear Stochastic Systems with Constant Coefficients

Directory of Open Access Journals (Sweden)

Peng Jiang

2013-01-01

Full Text Available The authors attempt to construct the exact finite-difference schemes for linear stochastic differential equations with constant coefficients. The explicit solutions to Itô and Stratonovich linear stochastic differential equations with constant coefficients are adopted with the view of providing exact finite-difference schemes to solve them. In particular, the authors utilize the exact finite-difference schemes of Stratonovich type linear stochastic differential equations to solve the Kubo oscillator that is widely used in physics. Further, the authors prove that the exact finite-difference schemes can preserve the symplectic structure and first integral of the Kubo oscillator. The authors also use numerical examples to prove the validity of the numerical methods proposed in this paper.

Tritons at energies of 10 MeV to 1 TeV: Conversion coefficients for fluence-to-absorbed dose, equivalent dose, effective dose, and gray equivalent, calculated using Monte Carlo radiation transport code MCNPX 2.7.C

International Nuclear Information System (INIS)

Copeland, K.; Parker, D. E.; Friedberg, W.

2010-01-01

Conversion coefficients were calculated for fluence-to-absorbed dose, fluence-to-equivalent dose, fluence-to-effective dose and fluence-to-gray equivalent for isotropic exposure of an adult female and an adult male to tritons ( 3 H + ) in the energy range of 10 MeV to 1 TeV (0.01-1000 GeV). Coefficients were calculated using Monte Carlo transport code MCNPX 2.7.C and BodyBuilder TM 1.3 anthropomorphic phantoms. Phantoms were modified to allow calculation of effective dose to a Reference Person using tissues and tissue weighting factors from 1990 and 2007 recommendations of the International Commission on Radiological Protection (ICRP) and calculation of gray equivalent to selected tissues as recommended by the National Council on Radiation Protection and Measurements. At 15 of the 19 energies for which coefficients for effective dose were calculated, coefficients based on ICRP 2007 and 1990 recommendations differed by less than 3%. The greatest difference, 43%, occurred at 30 MeV. Published by Oxford Univ. Press on behalf of the US Government 2010. (authors)

Engineering quadratic nonlinear photonic crystals for frequency conversion of lasers

Science.gov (United States)

Chen, Baoqin; Hong, Lihong; Hu, Chenyang; Zhang, Chao; Liu, Rongjuan; Li, Zhiyuan

2018-03-01

Nonlinear frequency conversion offers an effective way to extend the laser wavelength range. Quadratic nonlinear photonic crystals (NPCs) are artificial materials composed of domain-inversion structures whose sign of nonlinear coefficients are modulated with desire to implement quasi-phase matching (QPM) required for nonlinear frequency conversion. These structures can offer various reciprocal lattice vectors (RLVs) to compensate the phase-mismatching during the quadratic nonlinear optical processes, including second-harmonic generation (SHG), sum-frequency generation and the cascaded third-harmonic generation (THG). The modulation pattern of the nonlinear coefficients is flexible, which can be one-dimensional or two-dimensional (2D), be periodic, quasi-periodic, aperiodic, chirped, or super-periodic. As a result, these NPCs offer very flexible QPM scheme to satisfy various nonlinear optics and laser frequency conversion problems via design of the modulation patterns and RLV spectra. In particular, we introduce the electric poling technique for fabricating QPM structures, a simple effective nonlinear coefficient model for efficiently and precisely evaluating the performance of QPM structures, the concept of super-QPM and super-periodically poled lithium niobate for finely tuning nonlinear optical interactions, the design of 2D ellipse QPM NPC structures enabling continuous tunability of SHG in a broad bandwidth by simply changing the transport direction of pump light, and chirped QPM structures that exhibit broadband RLVs and allow for simultaneous radiation of broadband SHG, THG, HHG and thus coherent white laser from a single crystal. All these technical, theoretical, and physical studies on QPM NPCs can help to gain a deeper insight on the mechanisms, approaches, and routes for flexibly controlling the interaction of lasers with various QPM NPCs for high-efficiency frequency conversion and creation of novel lasers.

Solution of heat equation with variable coefficient using derive

CSIR Research Space (South Africa)

Lebelo, RS

2008-09-01

Full Text Available In this paper, the method of approximating solutions of partial differential equations with variable coefficients is studied. This is done by considering heat flow through a one-dimensional model with variable cross-sections. Two cases...

Absorption and emission from mode conversion theory

International Nuclear Information System (INIS)

Swanson, D.G.

1995-02-01

The effects of mode conversion theory on emission have led to some surprising results. The classical expressions were originally derived from models which did not include mode conversion or its attendant reflection. When mode conversion was included, the first surprise was that the transmission coefficient is totally independent of absorption and due exclusively to tunneling. The other surprise is that the observed emission arises from two distinct sources, one direct, and one from an indirect Bernstein wave source which is partially converted in the cyclotron layer to outgoing electromagnetic waves, with the net result that mode conversion cancels out for the electron case. The only corrections to electron cyclotron emission are then due to reflection effects, and these have been shown to be small for laboratory plasmas, leading to the validation of the classical formula, but via an entirely new paradigm in its interpretation. This paper includes a summary of the absorption process for electron cyclotron harmonics, and reviews the emission physics, including both potential error estimates and a discussion of the spatial emission source distribution

Thermoelectric conversion efficiency in IV-VI semiconductors with reduced thermal conductivity

Directory of Open Access Journals (Sweden)

Akihiro Ishida

2015-10-01

Full Text Available Mid-temperature thermoelectric conversion efficiencies of the IV-VI materials were calculated under the Boltzmann transport theory of carriers, taking the Seebeck, Peltier, and Thomson effects into account. The conversion efficiency was discussed with respect to the lattice thermal conductivity, keeping other parameters such as Seebeck coefficient and electrical conductivity to the same values. If room temperature lattice thermal conductivity is decreased up to 0.5W/mK, the conversion efficiency of a PbS based material becomes as high as 15% with the temperature difference of 500K between 800K and 300K.

Electromagnetic-gravitational conversion cross sections in external electromagnetic fields

International Nuclear Information System (INIS)

Hoang Ngoc Long; Dang Van Soa; Tuan Tran, A.

1994-09-01

The classical processes: the conversion of photons into gravitons in the static electromagnetic fields are considered by using Feynman perturbation techniques. The differential cross sections are presented for the conversion in the electric field of the flat condenser and the magnetic field of the solenoid. A numerical evaluation shows that the cross sections may have the observable value in the present technical scenario. (author). 11 refs

Seeley-Gilkey coefficients for the fourth-order operators on a Riemannian manifold

International Nuclear Information System (INIS)

Gusynin, V.P.

1989-01-01

A new covariant method for computing the coefficients in the heat kernel expansion is suggested. It allows one to calculate Seeley-Gilkey coefficients for both minimal and nonminimal differential operators acting on a vector bundle over a Riemannian manifold. The coefficients for the fourth-order minimal operators in arbitrary dimension of the space are calculated. In contrast to the second-order operators the coefficients for the fourth-order (and higher) operators turn out to be essentially dependent on the space dimension. The algorithmic character of the method suggested allows one to calculate coefficients by computer using the analytical calculation system. 19 refs.; 1 fig

Beam shape coefficients of the most general focused Gaussian laser beam for light scattering applications

International Nuclear Information System (INIS)

Lock, James A.

2013-01-01

The vector wave equation for electromagnetic waves, when subject to a number of constraints corresponding to propagation of a monochromatic beam, reduces to a pair of inhomogeneous differential equations describing the transverse electric and transverse magnetic polarized beam components. These differential equations are solved analytically to obtain the most general focused Gaussian beam to order s 4 , where s is the beam confinement parameter, and various properties of the most general Gaussian beam are then discussed. The radial fields of the most general Gaussian beam are integrated to obtain the on-axis beam shape coefficients of the generalized Lorenz–Mie theory formalism of light scattering. The beam shape coefficients are then compared with those of the localized Gaussian beam model and the Davis–Barton fifth-order symmetrized beam. -- Highlights: ► Derive the differential equation for the most general Gaussian beam. ► Solve the differential equation for the most general Gaussian beam. ► Determine the properties of the most general Gaussian beam. ► Determine the beam shape coefficients of the most general Gaussian beam

Penetration effect in internal conversion and nuclear structure

International Nuclear Information System (INIS)

Listengarten, M.A.

1978-01-01

The conditions for the appearance of the anomalous internal conversion coefficients (ICC) are considered, when the contribution of the penetration matrix element (PME) is of the order of or larger than the main part of the conversion matrix element. The experimental magnitudes of the nuclear PME agree well with those calculated in the framework of simple nuclear models, provided the magnitude of PME is not decreased due to the model -dependent selection rules. The magnitude of the anomaly ( lanbda parameter ) is compared with the exclusion factor of γ-transition relative to the Weisskopf estimation. The better is the model of the nucleus the weaker is the dependence of the lambda magnitude on the exclusion factor. ICC coefficients might be anomalous for those γ-transitions for which the exclusion factor calculated in the framework of more rigorous model are of the order of unity. In the ''ideal'' model of nucleus completely adequate to the true nuclear structure the dependence of the lambda penetration parameter on the exclusion factor vanishes

Defining the Ecological Coefficient of Performance for an Aircraft Propulsion System

Science.gov (United States)

Şöhret, Yasin

2018-05-01

The aircraft industry, along with other industries, is considered responsible these days regarding environmental issues. Therefore, the performance evaluation of aircraft propulsion systems should be conducted with respect to environmental and ecological considerations. The current paper aims to present the ecological coefficient of performance calculation methodology for aircraft propulsion systems. The ecological coefficient performance is a widely-preferred performance indicator of numerous energy conversion systems. On the basis of thermodynamic laws, the methodology used to determine the ecological coefficient of performance for an aircraft propulsion system is parametrically explained and illustrated in this paper for the first time. For a better understanding, to begin with, the exergy analysis of a turbojet engine is described in detail. Following this, the outputs of the analysis are employed to define the ecological coefficient of performance for a turbojet engine. At the end of the study, the ecological coefficient of performance is evaluated parametrically and discussed depending on selected engine design parameters and performance measures. The author asserts the ecological coefficient of performance to be a beneficial indicator for researchers interested in aircraft propulsion system design and related topics.

Study for discharge coefficient of flow nozzles. Prediction by using numerical simulation

International Nuclear Information System (INIS)

Ikeda, Hiroshi; Sakai, Norio; Yamamoto, Yasushi; Arai, Kenji; Matsumoto, Masaaki

2008-01-01

In nuclear plant, as water feeding into reactor have much effect on thermal power of plant, it is important to measure accurately the flow rate of water. Flow nozzle is on of typical differential pressure type flow meters and the discharge coefficient is used to calculate the flow rate. This coefficient is given by actual experiment and theory. We studied the theoretical assumption of the discharge coefficient curve using numerical simulation and evaluated the effect of flow nozzle configuration on the coefficient numerically and experimentally. As the result, numerical simulation can predict the discharge coefficient of theoretical curve within 0.3%. And we found that the throat length and throat tapping location of flow nozzle have much effect on the coefficient. (author)

Biomass pyrolysis and combustion integral and differential reaction heats with temperatures using thermogravimetric analysis/differential scanning calorimetry.

Science.gov (United States)

Shen, Jiacheng; Igathinathane, C; Yu, Manlu; Pothula, Anand Kumar

2015-06-01

Integral reaction heats of switchgrass, big bluestem, and corn stalks were determined using thermogravimetric analysis/differential scanning calorimetry (TGA/DSC). Iso-conversion differential reaction heats using TGA/DSC pyrolysis and combustion of biomass were not available, despite reports available on heats required and released. A concept of iso-conversion differential reaction heats was used to determine the differential reaction heats of each thermal characteristics segment of these materials. Results showed that the integral reaction heats were endothermic from 30 to 700°C for pyrolysis of switchgrass and big bluestem, but they were exothermic for corn stalks prior to 587°C. However, the integral reaction heats for combustion of the materials followed an endothermic to exothermic transition. The differential reaction heats of switchgrass pyrolysis were predominantly endothermic in the fraction of mass loss (0.0536-0.975), and were exothermic for corn stalks (0.0885-0.850) and big bluestem (0.736-0.919). Study results provided better insight into biomass thermal mechanism. Published by Elsevier Ltd.

Nonsuppressing normal thymus on chemical-shift MR imaging and anterior mediastinal lymphoma. Differentiation with diffusion-weighted MR imaging by using the apparent diffusion coefficient

International Nuclear Information System (INIS)

Priola, Adriano Massimiliano; Priola, Sandro Massimo; Gned, Dario; Veltri, Andrea; Giraudo, Maria Teresa

2018-01-01

To prospectively evaluate usefulness of the apparent diffusion coefficient (ADC) in differentiating anterior mediastinal lymphoma from nonsuppressing normal thymus on chemical-shift MR, and to look at the relationship between patient age and ADC. Seventy-three young subjects (25 men, 48 women; age range, 9-29 years), who underwent chemical-shift MR and diffusion-weighted MR were divided into a normal thymus group (group A, 40 subjects), and a lymphoma group (group B, 33 patients). For group A, all subjects had normal thymus with no suppression on opposed-phase chemical-shift MR. Two readers measured the signal intensity index (SII) and ADC. Differences in SII and ADC between groups were tested using t-test. ADC was correlated with age using Pearson correlation coefficient. Mean SII±standard deviation was 2.7±1.8% for group A and 2.2±2.4% for group B, with no significant difference between groups (P=.270). Mean ADC was 2.48±0.38 x 10 -3 mm 2 /s for group A and 1.24±0.23 x 10 -3 mm 2 /s for group B. A significant difference between groups was found (P<.001), with no overlap in range. Lastly, significant correlation was found between age and ADC (r=0.935, P<.001) in group A. ADC of diffusion-weighted MR is a noninvasive and accurate parameter for differentiating lymphoma from nonsuppressing thymus on chemical-shift MR in young subjects. (orig.)

The coefficients of the damping in the radioactive fall-out

International Nuclear Information System (INIS)

Stofanova, M.; Usacev, S.

1977-01-01

Radioactive fallout is characterized by time and seasonal variations. So far the independent growth of the 3 H, 90 Sr and 14 C fallout maxima was studied separately. The maxima and minima of the total fallout were compared with that of the above mentioned isotopes. Introducing the damping coefficient for monthly fallout, the seasonal and annual damping coefficients made is possible to determine time difference of the maxima of fallout for the individual components, namely: 3 H, 90 Sr and 14 C. Calculation of these coefficients yielded graphs markedly differentiating the maxima of the gross β activities for the years 1959 to 1973 and the said components of fallout. (author)

Effects of a random spatial variation of the plasma density on the mode conversion in cold, unmagnetized, and stratified plasmas

Energy Technology Data Exchange (ETDEWEB)

Jung Yu, Dae [School of Space Research, Kyung Hee University, Yongin 446-701 (Korea, Republic of); Kim, Kihong [Department of Energy Systems Research, Ajou University, Suwon 443-749 (Korea, Republic of)

2013-12-15

We study the effects of a random spatial variation of the plasma density on the mode conversion of electromagnetic waves into electrostatic oscillations in cold, unmagnetized, and stratified plasmas. Using the invariant imbedding method, we calculate precisely the electromagnetic field distribution and the mode conversion coefficient, which is defined to be the fraction of the incident wave power converted into electrostatic oscillations, for the configuration where a numerically generated random density variation is added to the background linear density profile. We repeat similar calculations for a large number of random configurations and take an average of the results. We obtain a peculiar nonmonotonic dependence of the mode conversion coefficient on the strength of randomness. As the disorder increases from zero, the maximum value of the mode conversion coefficient decreases initially, then increases to a maximum, and finally decreases towards zero. The range of the incident angle in which mode conversion occurs increases monotonically as the disorder increases. We present numerical results suggesting that the decrease of mode conversion mainly results from the increased reflection due to the Anderson localization effect originating from disorder, whereas the increase of mode conversion of the intermediate disorder regime comes from the appearance of many resonance points and the enhanced tunneling between the resonance points and the cutoff point. We also find a very large local enhancement of the magnetic field intensity for particular random configurations. In order to obtain high mode conversion efficiency, it is desirable to restrict the randomness close to the resonance region.

Effects of a random spatial variation of the plasma density on the mode conversion in cold, unmagnetized, and stratified plasmas

International Nuclear Information System (INIS)

Jung Yu, Dae; Kim, Kihong

2013-01-01

We study the effects of a random spatial variation of the plasma density on the mode conversion of electromagnetic waves into electrostatic oscillations in cold, unmagnetized, and stratified plasmas. Using the invariant imbedding method, we calculate precisely the electromagnetic field distribution and the mode conversion coefficient, which is defined to be the fraction of the incident wave power converted into electrostatic oscillations, for the configuration where a numerically generated random density variation is added to the background linear density profile. We repeat similar calculations for a large number of random configurations and take an average of the results. We obtain a peculiar nonmonotonic dependence of the mode conversion coefficient on the strength of randomness. As the disorder increases from zero, the maximum value of the mode conversion coefficient decreases initially, then increases to a maximum, and finally decreases towards zero. The range of the incident angle in which mode conversion occurs increases monotonically as the disorder increases. We present numerical results suggesting that the decrease of mode conversion mainly results from the increased reflection due to the Anderson localization effect originating from disorder, whereas the increase of mode conversion of the intermediate disorder regime comes from the appearance of many resonance points and the enhanced tunneling between the resonance points and the cutoff point. We also find a very large local enhancement of the magnetic field intensity for particular random configurations. In order to obtain high mode conversion efficiency, it is desirable to restrict the randomness close to the resonance region

Full-spectrum volumetric solar thermal conversion via photonic nanofluids.

Science.gov (United States)

Liu, Xianglei; Xuan, Yimin

2017-10-12

Volumetric solar thermal conversion is an emerging technique for a plethora of applications such as solar thermal power generation, desalination, and solar water splitting. However, achieving broadband solar thermal absorption via dilute nanofluids is still a daunting challenge. In this work, full-spectrum volumetric solar thermal conversion is demonstrated over a thin layer of the proposed 'photonic nanofluids'. The underlying mechanism is found to be the photonic superposition of core resonances, shell plasmons, and core-shell resonances at different wavelengths, whose coexistence is enabled by the broken symmetry of specially designed composite nanoparticles, i.e., Janus nanoparticles. The solar thermal conversion efficiency can be improved by 10.8% compared with core-shell nanofluids. The extinction coefficient of Janus dimers with various configurations is also investigated to unveil the effects of particle couplings. This work provides the possibility to achieve full-spectrum volumetric solar thermal conversion, and may have potential applications in efficient solar energy harvesting and utilization.

Apparent diffusion coefficient values and dynamic contrast enhancement patterns in differentiating seminomas from nonseminomatous testicular neoplasms

Energy Technology Data Exchange (ETDEWEB)

Tsili, Athina C., E-mail: a_tsili@yahoo.gr [Department of Radiology, Medical School, University of Ioannina, 45110 Ioannina (Greece); Sylakos, Anastasios, E-mail: anasylakos@yahoo.gr [Department of Urology, Medical School, University of Ioannina, 45110 Ioannina (Greece); Ntorkou, Alexandra, E-mail: alexdorkou@yahoo.com [Department of Radiology, Medical School, University of Ioannina, 45110 Ioannina (Greece); Stavrou, Sotirios, E-mail: s.sotiris@yahoo.gr [Department of Urology, Medical School, University of Ioannina, 45110 Ioannina (Greece); Astrakas, Loukas G., E-mail: astrakas@uoi.gr [Department of Medical Physics, Medical School, University of Ioannina, 45110 Ioannina (Greece); Sofikitis, Nikolaos, E-mail: akrosnin@hotmail.com [Department of Urology, Medical School, University of Ioannina, 45110 Ioannina (Greece); Argyropoulou, Maria I., E-mail: margyrop@cc.uoi.gr [Department of Radiology, Medical School, University of Ioannina, 45110 Ioannina (Greece)

2015-07-15

Highlights: • Functional MRI in the characterization of testicular germ cell tumors was assessed. • ADC values proved useful in the characterization of testicular germ cell tumors. • Testicular germ cell tumors had similar enhancement patterns of dynamic MRI. - Abstract: Introduction: The aim of this study is to investigate the role of apparent diffusion coefficient (ADC) values and dynamic contrast enhancement (DCE) patterns in differentiating seminomas from nonseminomatous germ cell tumors (NSGCTs). Materials and methods: The MRI examinations of the scrotum of 26 men with histologically proven testicular GCTs were reviewed. DWI was performed in all patients, using a single shot, multi-slice spin-echo planar diffusion pulse sequence and b-values of 0 and 900 s/mm{sup 2}. Subtraction DCE-MRI was performed in 20 cases using a 3D fast-field echo sequence after gadolinium administration. Time-signal intensity curves were created and semi-quantitative parameters (peak enhancement, time to peak, wash-in and wash-out rate) were calculated. The Student's t-test was used to compare the mean values of ADC, peak enhancement, time to peak, wash-in and wash-out rate between seminomas and NSGCTs. ROC analysis was also performed. Results: Histopathology disclosed the presence of 15 seminomas and 11 NSGCTs. The mean ± s.d. of ADC values (× 10{sup −3} mm{sup 2}/s) of seminomas (0.59 ± 0.009) were significantly lower than those of NSGCTs (0.90 ± 0.33) (P = 0.01). The optimal ADC cut-off value was 0.68 × 10{sup −3} mm{sup 2}/s. No differences between the two groups were observed for peak enhancement (P = 0.18), time to peak (P = 0.63) wash-in rate (P = 0.32) and wash-out rate (P = 0.18). Conclusions: ADC values may be used to preoperatively differentiate seminomas from NSGCTs.

Apparent diffusion coefficient values and dynamic contrast enhancement patterns in differentiating seminomas from nonseminomatous testicular neoplasms

International Nuclear Information System (INIS)

Tsili, Athina C.; Sylakos, Anastasios; Ntorkou, Alexandra; Stavrou, Sotirios; Astrakas, Loukas G.; Sofikitis, Nikolaos; Argyropoulou, Maria I.

2015-01-01

Highlights: • Functional MRI in the characterization of testicular germ cell tumors was assessed. • ADC values proved useful in the characterization of testicular germ cell tumors. • Testicular germ cell tumors had similar enhancement patterns of dynamic MRI. - Abstract: Introduction: The aim of this study is to investigate the role of apparent diffusion coefficient (ADC) values and dynamic contrast enhancement (DCE) patterns in differentiating seminomas from nonseminomatous germ cell tumors (NSGCTs). Materials and methods: The MRI examinations of the scrotum of 26 men with histologically proven testicular GCTs were reviewed. DWI was performed in all patients, using a single shot, multi-slice spin-echo planar diffusion pulse sequence and b-values of 0 and 900 s/mm 2 . Subtraction DCE-MRI was performed in 20 cases using a 3D fast-field echo sequence after gadolinium administration. Time-signal intensity curves were created and semi-quantitative parameters (peak enhancement, time to peak, wash-in and wash-out rate) were calculated. The Student's t-test was used to compare the mean values of ADC, peak enhancement, time to peak, wash-in and wash-out rate between seminomas and NSGCTs. ROC analysis was also performed. Results: Histopathology disclosed the presence of 15 seminomas and 11 NSGCTs. The mean ± s.d. of ADC values (× 10 −3 mm 2 /s) of seminomas (0.59 ± 0.009) were significantly lower than those of NSGCTs (0.90 ± 0.33) (P = 0.01). The optimal ADC cut-off value was 0.68 × 10 −3 mm 2 /s. No differences between the two groups were observed for peak enhancement (P = 0.18), time to peak (P = 0.63) wash-in rate (P = 0.32) and wash-out rate (P = 0.18). Conclusions: ADC values may be used to preoperatively differentiate seminomas from NSGCTs

A Two-Stage Estimation Method for Random Coefficient Differential Equation Models with Application to Longitudinal HIV Dynamic Data.

Science.gov (United States)

Fang, Yun; Wu, Hulin; Zhu, Li-Xing

2011-07-01

We propose a two-stage estimation method for random coefficient ordinary differential equation (ODE) models. A maximum pseudo-likelihood estimator (MPLE) is derived based on a mixed-effects modeling approach and its asymptotic properties for population parameters are established. The proposed method does not require repeatedly solving ODEs, and is computationally efficient although it does pay a price with the loss of some estimation efficiency. However, the method does offer an alternative approach when the exact likelihood approach fails due to model complexity and high-dimensional parameter space, and it can also serve as a method to obtain the starting estimates for more accurate estimation methods. In addition, the proposed method does not need to specify the initial values of state variables and preserves all the advantages of the mixed-effects modeling approach. The finite sample properties of the proposed estimator are studied via Monte Carlo simulations and the methodology is also illustrated with application to an AIDS clinical data set.

Usefulness of Apparent Diffusion Coefficient Values in the Nasopharynx and the Oropharynx: Differentiation of Benign and Malignant Lesions

International Nuclear Information System (INIS)

Kwon, Hoon; Kim, Hak Jin; Sol, Yu Li; Lee, Tae Hong; Yeom, Jeong A; Kim, Ah Rong

2012-01-01

In several previous studies, apparent diffusion coefficient (ADC) calculation was applied in the evaluation of head and neck tumors and is a promising technique for this application. As a result, we reevaluated the usefulness of ADC measurement with differentiation of benign and malignant pathology in the nasopharynx and oropharynx. The study population consisted of 87 consecutive patients who had undergone routine nasopharyngeal and oropharyngeal MR imaging at our institution, which included diffusion weighted image and ADC map, with a clinically suspected primary tumor of nasopharynx and oropharynx. The mean ADC values in the benign and malignant groups were compared and the malignant group was divided into the lymphoma and carcinoma groups. A statistically significant difference in ADC values among the benign and malignant groups using independent samples t-test with a p -3 mm 2 /s was used to distinguish between benign and malignancy, accuracy was 85%. ADC values were useful for distinguishing between benign and malignancy in the nasopharynx and oropharynx.

On the Energy Conversion Efficiency of Piezoelectric Vibration Energy Harvesting Devices

Energy Technology Data Exchange (ETDEWEB)

Kim, Jae Eun [Catholic University of Daegu, Kyungsan (Korea, Republic of)

2015-05-15

To properly design and assess a piezoelectric vibration energy harvester, it is necessary to consider the application of an efficiency measure of energy conversion. The energy conversion efficiency is defined in this work as the ratio of the electrical output power to the mechanical input power for a piezoelectric vibration energy harvester with an impedance-matched load resistor. While previous research works employed the electrical output power for approximate impedance-matched load resistance, this work derives an efficiency measure considering optimally matched resistance. The modified efficiency measure is validated by comparing it with finite element analysis results for piezoelectric vibration energy harvesters with three different values of the electro-mechanical coupling coefficient. New findings on the characteristics of energy conversion and conversion efficiency are also provided for the two different impedance matching methods.

Dual exponential polynomials and linear differential equations

Science.gov (United States)

Wen, Zhi-Tao; Gundersen, Gary G.; Heittokangas, Janne

2018-01-01

We study linear differential equations with exponential polynomial coefficients, where exactly one coefficient is of order greater than all the others. The main result shows that a nontrivial exponential polynomial solution of such an equation has a certain dual relationship with the maximum order coefficient. Several examples illustrate our results and exhibit possibilities that can occur.

Calculation of conversion coefficients for effective dose by using voxel phantoms with defined genus for radiodiagnostic common examinations

International Nuclear Information System (INIS)

Lima, F.R.A.; Kramer, R.; Khoury, H.J.; Vieira, J.W.; Loureiro, E.C.M.; Hoff, G.

2004-01-01

Patient exposure from radiological examinations is usually quantified in terms of average absorbed dose or equivalent dose to certain radiosensitive organs of the human body. As these quantities cannot be measured in vivo, it is common practice to use physical or computational exposure models, which simulate the exposure to the patient in order to determine not only the quantities of interest (absorbed or equivalent dose), but also at the same time measurable quantities for the exposure conditions given. The ratio between a quantity of interest and a measurable quantity is called a conversion coefficient (CC), which is a function of the source and field parameters (tube voltage, filtration, field size, field position, focus-to-skin distance, etc.), the anatomical properties of the phantom, the elemental composition of relevant body tissues, and the radiation transport method applied. As the effective dose represents a sum over 23 risk-weighted organ and tissue equivalent doses, its determination practically implies the measurement or calculation of a complete distribution of equivalent doses throughout the human body. This task can be resolved most efficiently by means of computational exposure models, which consist of a virtual representation of the human body, also called phantom, connected to a Monte Carlo radiation transport computer code. The recently introduced MAX (Male Adult voXel) and FAXht (Female Adult voXel) head+trunk phantoms have been chosen for this task. With respect to their anatomical properties these phantoms correspond fairly well to the data recommended by the ICRP for the Reference Adult Male and Female. (author)

The Role of Apparent Diffusion Coefficient Quantification in Differentiating Benign and Malignant Renal Masses by 3 Tesla Magnetic Resonance Imaging.

Science.gov (United States)

Göya, Cemil; Hamidi, Cihad; Bozkurt, Yaşar; Yavuz, Alpaslan; Kuday, Suzan; Gümüş, Hatice; Türkçü, Gül; Hattapoğlu, Salih; Bilici, Aslan

2015-07-01

Diffusion-weighted magnetic resonance imaging (DWI) is a widely-accepted diagnostic modality whose efficacy has been investigated by numerous past studies in the differentiation of malignant lesions from benign entities. The aim of this study was to evaluate the efficiency of diffusion-weighted magnetic resonance imaging in the characterization of renal lesions. Diagnostic accuracy study. A total of 137 patients with renal lesions were included in this study. The median apparent diffusion coefficient (ADC) values as well as the b 800 and b 1600 signal intensities of normal kidneys, solid components of mixed renal masses, and total cystic lesions were evaluated. There were significant differences between the ADC values of lesions and normal renal parenchyma, and between the ADC values of benign and malignant renal lesions on DWIs at b values of 800 and 1600 s/mm(2) (pbenign and malignant renal lesions. A cutoff value of 1.623 × 10(-3) mm(2)/s for the ADC with a b value of 1600 s/mm(2) provided 79% sensitivity and 96% specificity (pbenign and malignant renal lesions. Accurate assessment of renal masses is important for determining the necessity for surgical intervention. DWI provides additional value by differentiating benign from malignant renal tumors and can be added to routine kidney MRI protocols.

Second- and Higher-Order Virial Coefficients Derived from Equations of State for Real Gases

Science.gov (United States)

Parkinson, William A.

2009-01-01

Derivation of the second- and higher-order virial coefficients for models of the gaseous state is demonstrated by employing a direct differential method and subsequent term-by-term comparison to power series expansions. This communication demonstrates the application of this technique to van der Waals representations of virial coefficients.…

Schwarzian conditions for linear differential operators with selected differential Galois groups

International Nuclear Information System (INIS)

Abdelaziz, Y; Maillard, J-M

2017-01-01

We show that non-linear Schwarzian differential equations emerging from covariance symmetry conditions imposed on linear differential operators with hypergeometric function solutions can be generalized to arbitrary order linear differential operators with polynomial coefficients having selected differential Galois groups. For order three and order four linear differential operators we show that this pullback invariance up to conjugation eventually reduces to symmetric powers of an underlying order-two operator. We give, precisely, the conditions to have modular correspondences solutions for such Schwarzian differential equations, which was an open question in a previous paper. We analyze in detail a pullbacked hypergeometric example generalizing modular forms, that ushers a pullback invariance up to operator homomorphisms. We finally consider the more general problem of the equivalence of two different order-four linear differential Calabi–Yau operators up to pullbacks and conjugation, and clarify the cases where they have the same Yukawa couplings. (paper)

Schwarzian conditions for linear differential operators with selected differential Galois groups

Science.gov (United States)

Abdelaziz, Y.; Maillard, J.-M.

2017-11-01

We show that non-linear Schwarzian differential equations emerging from covariance symmetry conditions imposed on linear differential operators with hypergeometric function solutions can be generalized to arbitrary order linear differential operators with polynomial coefficients having selected differential Galois groups. For order three and order four linear differential operators we show that this pullback invariance up to conjugation eventually reduces to symmetric powers of an underlying order-two operator. We give, precisely, the conditions to have modular correspondences solutions for such Schwarzian differential equations, which was an open question in a previous paper. We analyze in detail a pullbacked hypergeometric example generalizing modular forms, that ushers a pullback invariance up to operator homomorphisms. We finally consider the more general problem of the equivalence of two different order-four linear differential Calabi-Yau operators up to pullbacks and conjugation, and clarify the cases where they have the same Yukawa couplings.

Role of nuclear penetration effects in spin assignments. [J, transitions, internal conversion

Energy Technology Data Exchange (ETDEWEB)

Sahota, H S [Punjabi Univ., Patiala (India). Dept. of Physics

1976-04-01

Nuclear penetrations have been found to affect the internal conversion process of the retarded magnetic dipole transitions. In all cases where the penetration coefficient has been found to be essentially different from unity the transition is 1-forbidden. This criterian has been applied to the case of 191 keV transition in /sup 197/Au where the spin of the 268 keV level could not be deduced uniquely by any of the existing methods. The result is that the 199 keV transition has a dynamic contribution to its internal conversion process with the penetration coefficient lambda = 5.5 +- 0.9. To illustrate the applicability of the criterian further two more cases namely that of the 92 keV transition in /sup 131/Cs and 182 keV transition in /sup 129/Cs are also included.

Study and construction of a {beta}-spectrometer of uniform axial magnetic field fitted with a {beta}-{gamma} coincidence selector. Study of the {beta} spectra of {sup 32}P, {sup 203}Hg, {sup 198}Au. Measurement of the conversion coefficients of {sup 203}Ti and of {sup 198}Hg; Etude et realisation d'un spectrometre-{beta} a champ magnetique axial uniforme, muni d'un selecteur de coincidence {beta}-{gamma}. Etude des spectres {beta} du {sup 32}p, {sup 203}Hg, {sup 198}Au. Mesure des coefficients de conversion du {sup 203}Ti et du {sup 198}Hg

Energy Technology Data Exchange (ETDEWEB)

Parsignault, D [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1964-06-01

In the first part is given the principle of the beta spectrometer with uniform axial field using systematically the idea of caustics. The apparatus is described and its properties compared to those deduced from trajectory calculations. The {beta}-ray and {gamma}-ray detectors and the device for selecting coincidences with a 2 {tau} resolution of 5 nanoseconds are also presented. In the second part, the spectrometer is used for studying reference elements and the most accurate results are confirmed. The {beta} spectrum of {sup 60}Co has a statistical form with an accuracy of 1 per cent; the maximum energy E{sub 0} is 316.5 {+-} 1.5 keV. That of the 7/2 + {yields} 11/2 transition for {sup 137}Cs has a unique form, once forbidden. E{sub 0}= 522 {+-} 3 keV. Conversion coefficients {alpha}{sub k} = 96 {+-} 1 X 10{sup -3} {alpha}L + M + N = 20.9 {+-} 0.5 X 10{sup -3}. The two {beta} spectra of {sup 59}Fe, separated by coincidence with the gamma, have the statistical form E{sub 0} = 462 {+-} 2 keV (55.1 + 0,3 per cent) and E{sub 1} = 275 {+-} 4 keV (44.9 {+-} 0.3 per cent). It is then verified whether the l selection rule is apparent in the shape of the phosphorus 32 beta spectrum. It is found in fact that it is not of statistical shape and its shape coefficient is determined. For a theoretical interpretation it is necessary to have better approximations than those generally used and this interpretation will not be unique. This work has also made it possible to show that the source contains a small proportion of {sup 33}P. The study of the {sup 203}Hg {beta} spectrum followed by the 279 keV gamma spectrum is designed to determine the conversion coefficients. The interior spectrum of gold 198 is not of statistical shape either. The form coefficient is determined together with the conversion coefficients which are in slight disagreement with those calculated by Rose or Sliv. An interpretation of the spectrum is put forward which proposes an imperfect compensation for the

Study and construction of a {beta}-spectrometer of uniform axial magnetic field fitted with a {beta}-{gamma} coincidence selector. Study of the {beta} spectra of {sup 32}P, {sup 203}Hg, {sup 198}Au. Measurement of the conversion coefficients of {sup 203}Ti and of {sup 198}Hg; Etude et realisation d'un spectrometre-{beta} a champ magnetique axial uniforme, muni d'un selecteur de coincidence {beta}-{gamma}. Etude des spectres {beta} du {sup 32}p, {sup 203}Hg, {sup 198}Au. Mesure des coefficients de conversion du {sup 203}Ti et du {sup 198}Hg

Energy Technology Data Exchange (ETDEWEB)

Parsignault, D. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1964-06-01

In the first part is given the principle of the beta spectrometer with uniform axial field using systematically the idea of caustics. The apparatus is described and its properties compared to those deduced from trajectory calculations. The {beta}-ray and {gamma}-ray detectors and the device for selecting coincidences with a 2 {tau} resolution of 5 nanoseconds are also presented. In the second part, the spectrometer is used for studying reference elements and the most accurate results are confirmed. The {beta} spectrum of {sup 60}Co has a statistical form with an accuracy of 1 per cent; the maximum energy E{sub 0} is 316.5 {+-} 1.5 keV. That of the 7/2 + {yields} 11/2 transition for {sup 137}Cs has a unique form, once forbidden. E{sub 0}= 522 {+-} 3 keV. Conversion coefficients {alpha}{sub k} = 96 {+-} 1 X 10{sup -3} {alpha}L + M + N = 20.9 {+-} 0.5 X 10{sup -3}. The two {beta} spectra of {sup 59}Fe, separated by coincidence with the gamma, have the statistical form E{sub 0} = 462 {+-} 2 keV (55.1 + 0,3 per cent) and E{sub 1} = 275 {+-} 4 keV (44.9 {+-} 0.3 per cent). It is then verified whether the l selection rule is apparent in the shape of the phosphorus 32 beta spectrum. It is found in fact that it is not of statistical shape and its shape coefficient is determined. For a theoretical interpretation it is necessary to have better approximations than those generally used and this interpretation will not be unique. This work has also made it possible to show that the source contains a small proportion of {sup 33}P. The study of the {sup 203}Hg {beta} spectrum followed by the 279 keV gamma spectrum is designed to determine the conversion coefficients. The interior spectrum of gold 198 is not of statistical shape either. The form coefficient is determined together with the conversion coefficients which are in slight disagreement with those calculated by Rose or Sliv. An interpretation of the spectrum is put forward which proposes an imperfect compensation for the

Helions at energies of 10 MeV to 1 TeV: Conversion coefficients for fluence-to-absorbed dose, equivalent dose, effective dose and gray equivalent, calculated using Monte Carlo radiation transport code MCNPX 2.7.C

International Nuclear Information System (INIS)

Copeland, K.; Parker, D. E.; Friedberg, W.

2010-01-01

Conversion coefficients were calculated for fluence-to-absorbed dose, fluence-to-equivalent dose, fluence-to-effective dose and fluence-to-gray equivalent, for isotropic exposure of an adult male and an adult female to helions ( 3 He 2+ ) in the energy range of 10 MeV to 1 TeV (0.01-1000 GeV). Calculations were performed using Monte Carlo transport code MCNPX 2.7.C and BodyBuilder TM 1.3 anthropomorphic phantoms modified to allow calculation of effective dose using tissues and tissue weighting factors from either the 1990 or 2007 recommendations of the International Commission on Radiological Protection (ICRP), and gray equivalent to selected tissues as recommended by the National Council on Radiation Protection and Measurements. At 15 of the 19 energies for which coefficients for effective dose were calculated, coefficients based on ICRP 2007 and 1990 recommendations differed by less than 2%. The greatest difference, 62%, occurred at 100 MeV. Published by Oxford Univ. Press on behalf of the U.S. Government 2010. (authors)

Ortho-para-H2 conversion by hydrogen exchange: comparison of theory and experiment.

Science.gov (United States)

Lique, François; Honvault, Pascal; Faure, Alexandre

2012-10-21

We report fully-quantum time-independent calculations of cross sections and rate coefficients for the collisional (de)excitation of H(2) by H. Our calculations are based on the H(3) global potential energy surface of Mielke et al. [J. Chem. Phys. 116, 4142 (2002)]. The reactive hydrogen exchange channels are taken into account. We show that the ortho-para and para-ortho conversion of H(2) are significant processes at temperatures above ~300 K and for the last process we provide the first comparison with available experimental rate coefficients between 300 and 444 K. The good agreement between theory and experiment is a new illustration of our detailed understanding of the simplest chemical reaction. The importance of the ortho-para-H(2) conversion by hydrogen exchange in astrophysics is discussed.

The conversion of exposures due to radon into the effective dose: the epidemiological approach

Energy Technology Data Exchange (ETDEWEB)

Beck, T.R. [Federal Office for Radiation Protection, Berlin (Germany)

2017-11-15

The risks and dose conversion coefficients for residential and occupational exposures due to radon were determined with applying the epidemiological risk models to ICRP representative populations. The dose conversion coefficient for residential radon was estimated with a value of 1.6 mSv year{sup -1} per 100 Bq m{sup -3} (3.6 mSv per WLM), which is significantly lower than the corresponding value derived from the biokinetic and dosimetric models. The dose conversion coefficient for occupational exposures with applying the risk models for miners was estimated with a value of 14 mSv per WLM, which is in good accordance with the results of the dosimetric models. To resolve the discrepancy regarding residential radon, the ICRP approaches for the determination of risks and doses were reviewed. It could be shown that ICRP overestimates the risk for lung cancer caused by residential radon. This can be attributed to a wrong population weighting of the radon-induced risks in its epidemiological approach. With the approach in this work, the average risks for lung cancer were determined, taking into account the age-specific risk contributions of all individuals in the population. As a result, a lower risk coefficient for residential radon was obtained. The results from the ICRP biokinetic and dosimetric models for both, the occupationally exposed working age population and the whole population exposed to residential radon, can be brought in better accordance with the corresponding results of the epidemiological approach, if the respective relative radiation detriments and a radiation-weighting factor for alpha particles of about ten are used. (orig.)

The conversion of exposures due to radon into the effective dose: the epidemiological approach

International Nuclear Information System (INIS)

Beck, T.R.

2017-01-01

The risks and dose conversion coefficients for residential and occupational exposures due to radon were determined with applying the epidemiological risk models to ICRP representative populations. The dose conversion coefficient for residential radon was estimated with a value of 1.6 mSv year -1 per 100 Bq m -3 (3.6 mSv per WLM), which is significantly lower than the corresponding value derived from the biokinetic and dosimetric models. The dose conversion coefficient for occupational exposures with applying the risk models for miners was estimated with a value of 14 mSv per WLM, which is in good accordance with the results of the dosimetric models. To resolve the discrepancy regarding residential radon, the ICRP approaches for the determination of risks and doses were reviewed. It could be shown that ICRP overestimates the risk for lung cancer caused by residential radon. This can be attributed to a wrong population weighting of the radon-induced risks in its epidemiological approach. With the approach in this work, the average risks for lung cancer were determined, taking into account the age-specific risk contributions of all individuals in the population. As a result, a lower risk coefficient for residential radon was obtained. The results from the ICRP biokinetic and dosimetric models for both, the occupationally exposed working age population and the whole population exposed to residential radon, can be brought in better accordance with the corresponding results of the epidemiological approach, if the respective relative radiation detriments and a radiation-weighting factor for alpha particles of about ten are used. (orig.)

Data on flow cell optimization for membrane-based electrokinetic energy conversion

Directory of Open Access Journals (Sweden)

David Nicolas Østedgaard-Munck

2017-12-01

Full Text Available This article elaborates on the design and optimization of a specialized flow cell for the measurement of direct conversion of pressure into electrical energy (Electrokinetic Energy Conversion, EKEC which has been presented in Østedgaard-Munck et al. (2017 [1]. Two main flow cell parameters have been monitored and optimized: A the hydraulic pressure profile on each side of the membrane introduced by pumps recirculating the electrolyte solution through the flow fields and B the electrical resistance between the current collectors across the combined flow cell. The latter parameter has been measured using four-point Electrochemical Impedance spectroscopy (EIS for different flow rates and concentrations. The total cell resistance consists of contributions from different components: the membrane (Rmem, anode charge transfer (RA, cathode charge transfer (RC, and ion diffusion in the porous electrodes (RD.The intrinsic membrane properties of Nafion 117 has been investigated experimentally in LiI/I2 solutions with concentrations ranging between 0.06 and 0.96 M and used to identify the preferred LiI/I2 solution concentration. This was achieved by measuring the solution uptake, internal solution concentration and ion exchange capacity. The membrane properties were further used to calculate the transport coefficients and electrokinetic Figure of merit in terms of the Uniform potential and Space charge models. Special attention has been put on the streaming potential coefficient which is an intrinsic property. Keywords: Electrokinetic energy conversion, Electrochemical flow cell, Conversion efficiency

Conversion disorder: a problematic diagnosis.

Science.gov (United States)

Nicholson, Timothy R J; Stone, Jon; Kanaan, Richard A A

2011-11-01

The diagnosis of conversion disorder is problematic. Since doctors have conceptually and practically differentiated the symptoms from neurological ('organic') disease it has been presumed to be a psychological disorder, but the psychological mechanism, and how this differs from feigning (conscious simulation), has remained elusive. Although misdiagnosis of neurological disease as conversion disorder is uncommon, it remains a concern for clinicians, particularly for psychiatrists who may be unaware of the positive ways in which neurologists can exclude organic disease. The diagnosis is anomalous in psychiatry in that current diagnostic systems require that feigning is excluded and that the symptoms can be explained psychologically. In practice, feigning is very difficult to either disprove or prove, and a psychological explanation cannot always be found. Studies of childhood and adult psychological precipitants have tended to support the relevance of stressful life events prior to symptom onset at the group level but they are not found in a substantial proportion of cases. These problems highlight serious theoretical and practical issues not just for the current diagnostic systems but for the concept of the disorder itself. Psychology, physiology and functional imaging techniques have been used in attempts to elucidate the neurobiology of conversion disorder and to differentiate it from feigning, but while intriguing results are emerging they can only be considered preliminary. Such work looks to a future that could refine our understanding of the disorder. However, until that time, the formal diagnostic requirement for associated psychological stressors and the exclusion of feigning are of limited clinical value. Simplified criteria are suggested which will also encourage cooperation between neurology and psychiatry in the management of these patients.

Sharp Spectral Asymptotics and Weyl Formula for Elliptic Operators with Non-smooth Coefficients

International Nuclear Information System (INIS)

Zielinski, Lech

1999-01-01

The aim of this paper is to give the Weyl formula for eigenvalues of self-adjoint elliptic operators, assuming that first-order derivatives of the coefficients are Lipschitz continuous. The approach is based on the asymptotic formula of Hoermander''s type for the spectral function of pseudo differential operators having Lipschitz continuous Hamiltonian flow and obtained via a regularization procedure of nonsmooth coefficients

SYNTHESIS, THERMAL STUDIES AND CONVERSION DEGREE OF DIMETHACRYLATE POLYMERS USING NEW NON-TOXIC COINITIATORS

Directory of Open Access Journals (Sweden)

Rafael Turra Alarcon

Full Text Available The aim of this paper is to replace toxic coinitiators (tertiary amines by non-toxic compounds such as glycerol and inositol (polyalcohol in dimethacrylate resins. For this purpose, mid infrared spectroscopy (MIR was used to calculate the monomers' degree of conversion (%DC; as well as simultaneous Thermogravimetric Analysis – Differential Thermal Analysis (TGA-DTA and Differential Scanning Calorimetry (DSC were conducted to evaluate thermal stability, degradation steps, and thermal events. The use of different initiator systems did not modify the thermal events or the thermal stability of each of the dimethacrylate resins. Results show a substitution of system 2 (toxicity by system 3 (low toxicity, which had a good conversion velocity and total conversion in some monomers, is plausible.

Lie Symmetry of the Diffusive Lotka–Volterra System with Time-Dependent Coefficients

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Vasyl’ Davydovych

2018-02-01

Full Text Available Lie symmetry classification of the diffusive Lotka–Volterra system with time-dependent coefficients in the case of a single space variable is studied. A set of such symmetries in an explicit form is constructed. A nontrivial ansatz reducing the Lotka–Volterra system with correctly-specified coefficients to the system of ordinary differential equations (ODEs and an example of the exact solution with a biological interpretation are found.

Gradient-based estimation of Manning's friction coefficient from noisy data

KAUST Repository

Calo, Victor M.

2013-01-01

We study the numerical recovery of Manning\\'s roughness coefficient for the diffusive wave approximation of the shallow water equation. We describe a conjugate gradient method for the numerical inversion. Numerical results for one-dimensional models are presented to illustrate the feasibility of the approach. Also we provide a proof of the differentiability of the weak form with respect to the coefficient as well as the continuity and boundedness of the linearized operator under reasonable assumptions using the maximal parabolic regularity theory. © 2012 Elsevier B.V. All rights reserved.

Gradient-based estimation of Manning's friction coefficient from noisy data

KAUST Repository

Calo, Victor M.; Collier, Nathan; Gehre, Matthias; Jin, Bangti; Radwan, Hany G.; Santillana, Mauricio

2013-01-01

We study the numerical recovery of Manning's roughness coefficient for the diffusive wave approximation of the shallow water equation. We describe a conjugate gradient method for the numerical inversion. Numerical results for one-dimensional models are presented to illustrate the feasibility of the approach. Also we provide a proof of the differentiability of the weak form with respect to the coefficient as well as the continuity and boundedness of the linearized operator under reasonable assumptions using the maximal parabolic regularity theory. © 2012 Elsevier B.V. All rights reserved.

Similarity solutions of the Fokker–Planck equation with time-dependent coefficients

International Nuclear Information System (INIS)

Lin, W.-T.; Ho, C.-L.

2012-01-01

In this work, we consider the solvability of the Fokker–Planck equation with both time-dependent drift and diffusion coefficients by means of the similarity method. By the introduction of the similarity variable, the Fokker–Planck equation is reduced to an ordinary differential equation. Adopting the natural requirement that the probability current density vanishes at the boundary, the resulting ordinary differential equation turns out to be integrable, and the probability density function can be given in closed form. New examples of exactly solvable Fokker–Planck equations are presented, and their properties analyzed. - Highlights: ► Scaling form of the Fokker–Planck equation with time-dependent drift and diffusion coefficients is derived. ► Exact similarity solution of the Fokker–Planck equation is given in closed forms. ► New examples of Fokker–Planck equations exactly solvable by similarity methods are discussed.

Experimental Investigations of Direct and Converse Flexoelectric Effect in Bilayer Lipid Membranes.

Science.gov (United States)

Todorov, Angelio Todorov

Flexoelectric coefficients (direct and converse), electric properties (capacitance and resistivity) and mechanical properties (thickness and elastic coefficients) have been determined for bilayer lipid membranes (BLMs) prepared from egg yolk lecithin (EYL), glycerol monoleate (GMO), phosphatidyl choline (PC) and phosphatidyl serine (PS) as a function of frequency, pH and surface charge modifiers. Direct flexoelectric effect manifested itself in the development of microvolt range a.c. potential (U_{f}) upon subjecting one side of a BLM to an oscillating hydrostatic pressure, in the 100-1000 Hz range. Operationally, the flexoelectric coefficient (f) is expressed by the ratio between U_{f} and the change of curvature (c) which accompanied the flexing of the membrane. Membrane curvature was determined by means of either the electric method (capacitance microphone effect) or by the newly developed method of stroboscopic interferometry. Real-time stroboscopic interferometry coupled with simultaneous electric measurements, provided a direct method for the determination of f. Two different frequency regimes of f were recognized. At low frequencies (300 Hz), associated with free mobility of the surfactant, f-values of 24.1 times 10^{-19} and 0.87 times 10^ {-19} Coulombs were obtained for PC and GMO BLMs. At high frequencies (>300 Hz), associated with blocked mobility of the surfactant, f-values of 16.5 times 10^ {-19} and 0.30 times 10^{-19} Coulombs were obtained for PC and GMO BLMs. The theoretically calculated value for the GMO BLM oscillating at high frequency (0.12 times 10^{-19 } Coulombs) agreed well with that determined experimentally (0.3 times 10 ^{-19} Coulombs). For charged bovine brain PS BLM the observed flexocoefficient was f = 4.0 times 10^{ -18} Coulombs. Converse flexoelectric effect manifested itself in voltage-induced BLM curvature. Observations were carried out on uranyl acetate (UA) stabilized PS BLM under a.c. excitation. Frequency dependence of f

Apparent diffusion coefficient in the analysis of prostate cancer: determination of optimal b-value pair to differentiate normal from malignant tissue.

Science.gov (United States)

Adubeiro, Nuno; Nogueira, Maria Luísa; Nunes, Rita G; Ferreira, Hugo Alexandre; Ribeiro, Eduardo; La Fuente, José Maria Ferreira

Determining optimal b-value pair for differentiation between normal and prostate cancer (PCa) tissues. Forty-three patients with diagnosis or PCa symptoms were included. Apparent diffusion coefficient (ADC) was estimated using minimum and maximum b-values of 0, 50, 100, 150, 200, 500s/mm2 and 500, 800, 1100, 1400, 1700 and 2000s/mm2, respectively. Diagnostic performances were evaluated when Area-under-the-curve (AUC)>95%. 15 of the 35 b-values pair surpassed this AUC threshold. The pair (50, 2000s/mm2) provided the highest AUC (96%) with ADC cutoff 0.89×10- 3 mm 2 /s, sensitivity 95.5%, specificity 93.2% and accuracy 94.4%. The best b-value pair was b=50, 2000s/mm2. Copyright © 2017 Elsevier Inc. All rights reserved.

Sharp Spectral Asymptotics and Weyl Formula for Elliptic Operators with Non-smooth Coefficients

Energy Technology Data Exchange (ETDEWEB)

Zielinski, Lech [Universite Paris 7 (D. Diderot), Institut de Mathematiques de Paris-Jussieu UMR9994 (France)

1999-09-15

The aim of this paper is to give the Weyl formula for eigenvalues of self-adjoint elliptic operators, assuming that first-order derivatives of the coefficients are Lipschitz continuous. The approach is based on the asymptotic formula of Hoermander''s type for the spectral function of pseudo differential operators having Lipschitz continuous Hamiltonian flow and obtained via a regularization procedure of nonsmooth coefficients.

A class of degenerate stochastic differential equations with non ...

Indian Academy of Sciences (India)

Introduction. In this article we consider (possibly degenerate) stochastic differential equations (SDEs) with non-Lipschitz coefficients. If the coefficients are Lipschitz, we can prove the existence of a unique strong solution (see [9]). But uniqueness fails in the case of non-Lipschitz coefficients. The literature on this topic is not ...

On the reduction of the degree of linear differential operators

International Nuclear Information System (INIS)

Bobieński, Marcin; Gavrilov, Lubomir

2011-01-01

Let L be a linear differential operator with coefficients in some differential field k of characteristic zero with algebraically closed field of constants. Let k a be the algebraic closure of k. For a solution y 0 , Ly 0 = 0, we determine the linear differential operator of minimal degree L-tilde and coefficients in k a , such that L-tilde y 0 =0. This result is then applied to some Picard–Fuchs equations which appear in the study of perturbations of plane polynomial vector fields of Lotka–Volterra type

Time-varying coefficient estimation in SURE models. Application to portfolio management

DEFF Research Database (Denmark)

Casas, Isabel; Ferreira, Eva; Orbe, Susan

This paper provides a detailed analysis of the asymptotic properties of a kernel estimator for a Seemingly Unrelated Regression Equations model with time-varying coefficients (tv-SURE) under very general conditions. Theoretical results together with a simulation study differentiates the cases...

Ortho-para H₂ conversion by proton exchange at low temperature: an accurate quantum mechanical study.

Science.gov (United States)

Honvault, P; Jorfi, M; González-Lezana, T; Faure, A; Pagani, L

2011-07-08

We report extensive, accurate fully quantum, time-independent calculations of cross sections at low collision energies, and rate coefficients at low temperatures for the H⁺ + H₂(v = 0, j) → H⁺ + H₂(v = 0, j') reaction. Different transitions are considered, especially the ortho-para conversion (j = 1 → j' = 0) which is of key importance in astrophysics. This conversion process appears to be very efficient and dominant at low temperature, with a rate coefficient of 4.15 × 10⁻¹⁰ cm³ molecule⁻¹ s⁻¹ at 10 K. The quantum mechanical results are also compared with statistical quantum predictions and the reaction is found to be statistical in the low temperature regime (T < 100 K).

High energy photon reference for radiation protection: technical design of the LINAC beam and ionization chambers; and calculation of monoenergetic conversion coefficients

Directory of Open Access Journals (Sweden)

Dusciac D.

2016-01-01

Full Text Available In this work, we present the results of the first part of a research project aimed at offering a complete response to dosimeters providers and nuclear physicists’ demands for high-energy (6 – 9 MeV photon beams for radiation protection purposes. Classical facilities allowing the production of high-energy photonic radiation (proton accelerators, nuclear reactors are very rare and need large investment for development and use. A novel solution is proposed, consisting in the use of a medical linear accelerator, allowing a significant decrease of all costs.Using Monte Carlo simulations (MCNP5 and PENELOPE codes, a specifically designed electron-photon conversion target allowing for obtaining a high energy photon beam (with an average energy weighted by fluence of about 6 MeV has been built for radiation protection purposes. Due to the specific design of the target, this “realistic” radiation protection high-energy photon beam presents a uniform distribution of air kerma rate at a distance of 1 m, over a 30 × 30 cm2 surface. Two graphite cavity ionizing chambers for ionometric measurements have been built. For one of these chambers, the charge collection volume has been measured allowing for its use as a primary standard. The second ionizing chamber is used as a transfer standard; as such it has been calibrated in a 60Co beam, and in the high energy photon beam for radiation protection.The measurements with these ionizing chambers allowed for an evaluation of the air kerma rate in the LINAC based high-energy photon beam for radiation protection: the values cover a range between 36 mGy/h and 210 mGy/h, compatible with radiation protection purposes.Finally, using Monte Carlo simulations, conversion coefficients from air kerma to dose equivalent quantities have been calculated in the range between 10 keV and 22.4 MeV, for the spectral distribution of the fluence corresponding to the beam produced by the linear accelerator of the LNE-LNHB.

Seeley-De Witt coefficients in a Riemann-Cartan manifold

International Nuclear Information System (INIS)

Cognola, G.; Zerbini, S.; Istituto Nazionale di Fisica Nucleare, Povo

1988-01-01

A new derivation of the first two coefficients of the heat kernel expansion for a second-order elliptic differential operator on a Riemann-Cartan manifold with arbitrary torsion is given. The expressions are presented in a very compact and tractable form useful for physical applications. Comparisons with other similar results that appeared in the literature are briefly discussed. (orig.)

Measurement of secondary cosmic radiation and calculation of associated dose conversion coefficients for humans; Messung sekundaerer kosmischer Strahlung und Berechnung der zugehoerigen Dosiskonversionskoeffizienten fuer den Menschen

Energy Technology Data Exchange (ETDEWEB)

Simmer, Gregor

2012-04-11

Due to secondary cosmic radiation (SCR), pilots and flight attendants receive elevated effective doses at flight altitudes. For this reason, since 2003 aircrew members are considered as occupationally exposed, in Germany. This work deals with the calculation of dose conversion coefficients (DCC) for protons, neutrons, electrons, positrons, photons and myons, which are crucial for estimation of effective dose from SCR. For the first time, calculations were performed combining Geant4 - a Monte Carlo code developed at CERN - with the voxel phantoms for the reference female and male published in 2008 by ICRP and ICRU. Furthermore, measurements of neutron fluence spectra - which contribute the major part to the effective dose of SCR - were carried out at the Environmental Research Station Schneefernerhaus (UFS) located at 2650 m above sea level nearby the Zugspitze mountain, Germany. These measured neutron spectra, and additionally available calculated spectra, were then folded with the DCC calculated in this work, and effective dose rates for different heights were calculated.

Diffusion coefficients of tracers in glassy polymer systems prepared by gamma radiolysis

International Nuclear Information System (INIS)

Tonge, M.P.; Gilbert, R.G.

1996-01-01

Diffusion-controlled reactions are common in free radical polymerisation reactions, especially in glassy polymer matrices. Such reactions commonly have an important influence on the polymerisation process and final polymer properties. For example, the dominant growth-stopping event (bimolecular termination) is generally diffusion-controlled. In glassy polymer systems, where molecular mobility is very low, the chain growth mechanism (propagation) may become diffusion-controlled. At present, the mechanism for propagation in glassy polymers is poorly understood, but it is expected by the Smoluchowski expression applied to propagation to depend strongly on the diffusion coefficient of monomer. The objective of this study is to measure reliable diffusion coefficients of small tracer molecules in glassy polymers, and compare these with propagation rate coefficients in similar systems, by the prediction above. Samples were initially prepared in a sealed sampled cell containing monomer, inert diluent, and tracer dye. After irradiation for several days, complete conversion of monomer to polymer can be obtained. The diffusion coefficients for two tracer dyes have been measured as a function of weight fraction polymer glassy poly(methyl methacrylate) samples

Gas-liquid mass transfer coefficient of methane in bubble column reactor

International Nuclear Information System (INIS)

Lee, Jaewon; Ha, Kyoung-Su; Lee, Jinwon; Kim, Choongik; Yasin, Muhammad; Park, Shinyoung; Chang, In Seop; Lee, Eun Yeol

2015-01-01

Biological conversion of methane gas has been attracting considerable recent interest. However, methanotropic bioreactor is limited by low solubility of methane gas in aqueous solution. Although a large mass transfer coefficient of methane in water could possibly overcome this limitation, no dissolved methane probe in aqueous environment is commercially available. We have developed a reactor enabling the measurement of aqueous phase methane concentration and mass transfer coefficient (k L a). The feasibility of the new reactor was demonstrated by measuring k L a values as a function of spinning rate of impeller and flow rate of methane gas. Especially, at spinning rate of 300 rpm and flow rate of 3.0 L/min, a large k L a value of 102.9 h -1 was obtained

Space-dependent perfusion coefficient estimation in a 2D bioheat transfer problem

Science.gov (United States)

Bazán, Fermín S. V.; Bedin, Luciano; Borges, Leonardo S.

2017-05-01

In this work, a method for estimating the space-dependent perfusion coefficient parameter in a 2D bioheat transfer model is presented. In the method, the bioheat transfer model is transformed into a time-dependent semidiscrete system of ordinary differential equations involving perfusion coefficient values as parameters, and the estimation problem is solved through a nonlinear least squares technique. In particular, the bioheat problem is solved by the method of lines based on a highly accurate pseudospectral approach, and perfusion coefficient values are estimated by the regularized Gauss-Newton method coupled with a proper regularization parameter. The performance of the method on several test problems is illustrated numerically.

A comparison of two indices for the intraclass correlation coefficient.

Science.gov (United States)

Shieh, Gwowen

2012-12-01

In the present study, we examined the behavior of two indices for measuring the intraclass correlation in the one-way random effects model: the prevailing ICC(1) (Fisher, 1938) and the corrected eta-squared (Bliese & Halverson, 1998). These two procedures differ both in their methods of estimating the variance components that define the intraclass correlation coefficient and in their performance of bias and mean squared error in the estimation of the intraclass correlation coefficient. In contrast with the natural unbiased principle used to construct ICC(1), in the present study it was analytically shown that the corrected eta-squared estimator is identical to the maximum likelihood estimator and the pairwise estimator under equal group sizes. Moreover, the empirical results obtained from the present Monte Carlo simulation study across various group structures revealed the mutual dominance relationship between their truncated versions for negative values. The corrected eta-squared estimator performs better than the ICC(1) estimator when the underlying population intraclass correlation coefficient is small. Conversely, ICC(1) has a clear advantage over the corrected eta-squared for medium and large magnitudes of population intraclass correlation coefficient. The conceptual description and numerical investigation provide guidelines to help researchers choose between the two indices for more accurate reliability analysis in multilevel research.

Differential equations extended to superspace

International Nuclear Information System (INIS)

Torres, J.; Rosu, H.C.

2003-01-01

We present a simple SUSY Ns = 2 superspace extension of the differential equations in which the sought solutions are considered to be real superfields but maintaining the common derivative operators and the coefficients of the differential equations unaltered. In this way, we get self consistent systems of coupled differential equations for the components of the superfield. This procedure is applied to the Riccati equation, for which we obtain in addition the system of coupled equations corresponding to the components of the general superfield solution. (Author)

Differential equations extended to superspace

Energy Technology Data Exchange (ETDEWEB)

Torres, J. [Instituto de Fisica, Universidad de Guanajuato, A.P. E-143, Leon, Guanajuato (Mexico); Rosu, H.C. [Instituto Potosino de Investigacion Cientifica y Tecnologica, A.P. 3-74, Tangamanga, San Luis Potosi (Mexico)

2003-07-01

We present a simple SUSY Ns = 2 superspace extension of the differential equations in which the sought solutions are considered to be real superfields but maintaining the common derivative operators and the coefficients of the differential equations unaltered. In this way, we get self consistent systems of coupled differential equations for the components of the superfield. This procedure is applied to the Riccati equation, for which we obtain in addition the system of coupled equations corresponding to the components of the general superfield solution. (Author)

Conversion of photons into spinless particles in periodic external electromagnetic field

International Nuclear Information System (INIS)

Hoang Ngoc Long; Dang Van Soa

1996-08-01

The conversion of photons into axions and dilatons in a periodic external electromagnetic field, namely in the TE 10 mode, are considered in detail. The differential cross sections are given. (author). 16 refs

Conversion between Addenbrooke's Cognitive Examination III and Mini-Mental State Examination.

Science.gov (United States)

Matías-Guiu, Jordi A; Pytel, Vanesa; Cortés-Martínez, Ana; Valles-Salgado, María; Rognoni, Teresa; Moreno-Ramos, Teresa; Matías-Guiu, Jorge

2017-12-10

We aim to provide a conversion between Addenbrooke's Cognitive Examination III (ACE-III) and Mini-Mental State Examination (MMSE) scores, to predict the MMSE result based on ACE-III, thus avoiding the need for both tests, and improving their comparability. Equipercentile equating method was used to elaborate a conversion table using a group of 400 participants comprising healthy controls and Alzheimer's disease (AD) patients. Then, reliability was assessed in a group of 100 healthy controls and patients with AD, 52 with primary progressive aphasia and 22 with behavioral variant frontotemporal dementia. The conversion table between ACE-III and MMSE denoted a high reliability, with intra-class correlation coefficients of 0.940, 0.922, and 0.902 in the groups of healthy controls and AD, behavioral variant frontotemporal dementia, and primary progressive aphasia, respectively. Our conversion table between ACE-III and MMSE suggests that MMSE may be estimated based on the ACE-III score, which could be useful for clinical and research purposes.

Differential intrathecal inflammatory markers in acute optic neuritis and later conversion to multiple sclerosis

DEFF Research Database (Denmark)

Olesen, Mads Nikolaj; Soelberg, Kerstin; Nilsson, Anna Christine

Background: Optic neuritis (ON) is often an early inflammatory, demyelinating event of multiple sclerosis (MS). We proffer that cytokine and chemokine profiles may (a) differ between patients with MS-related ON and those with non-MS-related ON and (b) predict conversion to MS in patients presenting......-up compared to those who had not. These findings are of potential relevance to our understanding of the pathogenesis of MS and may predict conversion of ON to MS....

Calculation of conversion coefficients of dose of a computational anthropomorphic simulator sit exposed to a plane source; Calculo de coeficientes de conversao de dose de um simulador antropomorfico computacional sentado exposto a uma fonte plana

Energy Technology Data Exchange (ETDEWEB)

Santos, William S.; Carvalho Junior, Alberico B. de; Pereira, Ariana J.S.; Santos, Marcos S.; Maia, Ana F., E-mail: williathan@yahoo.com.b, E-mail: ablohem@gmail.co, E-mail: ariana-jsp@hotmail.co, E-mail: m_souzasantos@hotmail.co, E-mail: afmaia@ufs.b [Universidade Federal de Sergipe (UFS), Aracaju, SE (Brazil)

2011-10-26

In this paper conversion coefficients (CCs) of equivalent dose and effective in terms of kerma in the air were calculated suggested by the ICRP 74. These dose coefficients were calculated considering a plane radiation source and monoenergetic for a spectrum of energy varying from 10 keV to 2 MeV. The CCs were obtained for four geometries of irradiation, anterior-posterior, posterior-anterior, lateral right side and lateral left side. It was used the radiation transport code Visual Monte Carlo (VMC), and a anthropomorphic simulator of sit female voxel. The observed differences in the found values for the CCs at the four irradiation sceneries are direct results of the body organs disposition, and the distance of these organs to the irradiation source. The obtained CCs will be used for estimative more precise of dose in situations that the exposed individual be sit, as the normally the CCs available in the literature were calculated by using simulators always lying or on their feet

Histogram analysis of apparent diffusion coefficient maps for the differentiation between lymphoma and metastatic lymph nodes of squamous cell carcinoma in head and neck region.

Science.gov (United States)

Wang, Yan-Jun; Xu, Xiao-Quan; Hu, Hao; Su, Guo-Yi; Shen, Jie; Shi, Hai-Bin; Wu, Fei-Yun

2018-06-01

Background To clarify the nature of cervical malignant lymphadenopathy is highly important for the diagnosis and differential diagnosis of head and neck tumors. Purpose To investigate the role of first-order apparent diffusion coefficient (ADC) histogram analysis for differentiating lymphoma from metastatic lymph nodes of squamous cell carcinoma (SCC) in the head and neck region. Material and Methods Diffusion-weighted imaging (DWI) data of 67 patients (lymphoma, n = 20; SCC, n = 47) with malignant lymphadenopathy were retrospectively analyzed. The SCC group was divided into nasopharyngeal SCC and non-nasopharyngeal SCC groups. The ADC histogram features (ADC 10 , ADC 25 , ADC mean , ADC median , ADC 75 , ADC 90 , skewness, and kurtosis) were derived and then compared by independent-samples t-test and one-way analysis of variance test, respectively. Receiver operating characteristic curve analyses were employed to investigate diagnostic performance of the significant parameters. Results Lymphoma showed significantly lower ADC mean , ADC median , ADC 75 , and ADC 90 than SCC (all P  0.05). Lymphoma showed significantly lower ADC 25 , ADC mean , ADC median , ADC 75 , and ADC 90 than non-nasopharyngeal SCC (all P histogram analysis is capable of differentiating lymphoma from metastatic lymph nodes of SCC, especially those of non-nasopharyngeal SCC.

Molecular extinction coefficients of lead sulfide and polymerized diaminobenzidine as final reaction products of histochemical phosphatase reactions

NARCIS (Netherlands)

van Noorden, C. J.; Jonges, G. N.

1992-01-01

Molar extinction coefficients of precipitated lead sulfide (PbS) and polymerized diaminobenzidine (polyDAB) have been determined at wavelengths of 450 nm and 480 nm, respectively, for quantitative histochemical analysis of phosphatase reactions. These values are essential for the conversion of

An introduction to linear ordinary differential equations using the impulsive response method and factorization

CERN Document Server

Camporesi, Roberto

2016-01-01

This book presents a method for solving linear ordinary differential equations based on the factorization of the differential operator. The approach for the case of constant coefficients is elementary, and only requires a basic knowledge of calculus and linear algebra. In particular, the book avoids the use of distribution theory, as well as the other more advanced approaches: Laplace transform, linear systems, the general theory of linear equations with variable coefficients and variation of parameters. The case of variable coefficients is addressed using Mammana’s result for the factorization of a real linear ordinary differential operator into a product of first-order (complex) factors, as well as a recent generalization of this result to the case of complex-valued coefficients.

Legendre-tau approximations for functional differential equations

Science.gov (United States)

Ito, K.; Teglas, R.

1986-01-01

The numerical approximation of solutions to linear retarded functional differential equations are considered using the so-called Legendre-tau method. The functional differential equation is first reformulated as a partial differential equation with a nonlocal boundary condition involving time-differentiation. The approximate solution is then represented as a truncated Legendre series with time-varying coefficients which satisfy a certain system of ordinary differential equations. The method is very easy to code and yields very accurate approximations. Convergence is established, various numerical examples are presented, and comparison between the latter and cubic spline approximation is made.

A Profile-Based Framework for Factorial Similarity and the Congruence Coefficient.

Science.gov (United States)

Hartley, Anselma G; Furr, R Michael

2017-01-01

We present a novel profile-based framework for understanding factorial similarity in the context of exploratory factor analysis in general, and for understanding the congruence coefficient (a commonly used index of factor similarity) specifically. First, we introduce the profile-based framework articulating factorial similarity in terms of 3 intuitive components: general saturation similarity, differential saturation similarity, and configural similarity. We then articulate the congruence coefficient in terms of these components, along with 2 additional profile-based components, and we explain how these components resolve ambiguities that can be-and are-found when using the congruence coefficient. Finally, we present secondary analyses revealing that profile-based components of factorial are indeed linked to experts' actual evaluations of factorial similarity. Overall, the profile-based approach we present offers new insights into the ways in which researchers can examine factor similarity and holds the potential to enhance researchers' ability to understand the congruence coefficient.

Flexible Conversion Ratio Fast Reactor Systems Evaluation

Energy Technology Data Exchange (ETDEWEB)

Neil Todreas; Pavel Hejzlar

2008-06-30

Conceptual designs of lead-cooled and liquid salt-cooled fast flexible conversion ratio reactors were developed. Both concepts have cores reated at 2400 MWt placed in a large-pool-type vessel with dual-free level, which also contains four intermediate heat exchanges coupling a primary coolant to a compact and efficient supercritical CO2 Brayton cycle power conversion system. Decay heat is removed passively using an enhanced Reactor Vessel Auxiliary Cooling System and a Passive Secondary Auxiliary Cooling System. The most important findings were that (1) it is feasible to design the lead-cooled and salt-cooled reactor with the flexible conversion ratio (CR) in the range of CR=0 and CR=1 n a manner that achieves inherent reactor shutdown in unprotected accidents, (2) the salt-cooled reactor requires Lithium thermal Expansion Modules to overcme the inherent salt coolant's large positive coolant temperature reactivity coefficient, (3) the preferable salt for fast spectrum high power density cores is NaCl-Kcl-MgCl2 as opposed to fluoride salts due to its better themal-hydraulic and neutronic characteristics, and (4) both reactor, but attain power density 3 times smaller than that of the sodium-cooled reactor.

Flexible Conversion Ratio Fast Reactor Systems Evaluation

International Nuclear Information System (INIS)

Neil Todreas; Pavel Hejzlar

2008-01-01

Conceptual designs of lead-cooled and liquid salt-cooled fast flexible conversion ratio reactors were developed. Both concepts have cores treated at 2400 MWt placed in a large-pool-type vessel with dual-free level, which also contains four intermediate heat exchanges coupling a primary coolant to a compact and efficient supercritical CO2 Brayton cycle power conversion system. Decay heat is removed passively using an enhanced Reactor Vessel Auxiliary Cooling System and a Passive Secondary Auxiliary Cooling System. The most important findings were that (1) it is feasible to design the lead-cooled and salt-cooled reactor with the flexible conversion ratio (CR) in the range of CR=0 and CR=1 n a manner that achieves inherent reactor shutdown in unprotected accidents, (2) the salt-cooled reactor requires Lithium thermal Expansion Modules to overcome the inherent salt coolant's large positive coolant temperature reactivity coefficient, (3) the preferable salt for fast spectrum high power density cores is NaCl-Kcl-MgCl2 as opposed to fluoride salts due to its better thermal-hydraulic and neutronic characteristics, and (4) both reactor, but attain power density 3 times smaller than that of the sodium-cooled reactor

Diagnostic performance of conventional MRI parameters and apparent diffusion coefficient values in differentiating between benign and malignant soft-tissue tumours.

Science.gov (United States)

Song, Y; Yoon, Y C; Chong, Y; Seo, S W; Choi, Y-L; Sohn, I; Kim, M-J

2017-08-01

To compare the abilities of conventional magnetic resonance imaging (MRI) and apparent diffusion coefficient (ADC) in differentiating between benign and malignant soft-tissue tumours (STT). A total of 123 patients with STT who underwent 3 T MRI, including diffusion-weighted imaging (DWI), were retrospectively analysed using variate conventional MRI parameters, ADC mean and ADC min . For the all-STT group, the correlation between the malignant STT conventional MRI parameters, except deep compartment involvement, compared to those of benign STT were statistically significant with univariate analysis. Maximum diameter of the tumour (p=0.001; odds ratio [OR], 8.97) and ADC mean (p=0.020; OR, 4.30) were independent factors with multivariate analysis. For the non-myxoid non-haemosiderin STT group, signal heterogeneity on axial T1-weighted imaging (T1WI; p=0.017), ADC mean , and ADC min (p=0.001, p=0.001), showed significant differences with univariate analysis between malignancy and benignity. Signal heterogeneity in axial T1WI (p=0.025; OR, 12.64) and ADC mean (p=0.004; OR, 33.15) were independent factors with multivariate analysis. ADC values as well as conventional MRI parameters were useful in differentiating between benign and malignant STT. The ADC mean was the most powerful diagnostic parameter in non-myxoid non-haemosiderin STT. Copyright © 2017 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.

Development of Falling Film Heat Transfer Coefficient for Industrial Chemical Processes Evaporator Design

KAUST Repository

Shahzad, Muhammad Wakil; Burhan, Muhammad; Ng, Kim Choon

2018-01-01

In falling film evaporators, the overall heat transfer coefficient is controlled by film thickness, velocity, liquid properties and the temperature differential across the film layer. This chapter presents the heat transfer behaviour for evaporative

High-Order Model and Dynamic Filtering for Frame Rate Up-Conversion.

Science.gov (United States)

Bao, Wenbo; Zhang, Xiaoyun; Chen, Li; Ding, Lianghui; Gao, Zhiyong

2018-08-01

This paper proposes a novel frame rate up-conversion method through high-order model and dynamic filtering (HOMDF) for video pixels. Unlike the constant brightness and linear motion assumptions in traditional methods, the intensity and position of the video pixels are both modeled with high-order polynomials in terms of time. Then, the key problem of our method is to estimate the polynomial coefficients that represent the pixel's intensity variation, velocity, and acceleration. We propose to solve it with two energy objectives: one minimizes the auto-regressive prediction error of intensity variation by its past samples, and the other minimizes video frame's reconstruction error along the motion trajectory. To efficiently address the optimization problem for these coefficients, we propose the dynamic filtering solution inspired by video's temporal coherence. The optimal estimation of these coefficients is reformulated into a dynamic fusion of the prior estimate from pixel's temporal predecessor and the maximum likelihood estimate from current new observation. Finally, frame rate up-conversion is implemented using motion-compensated interpolation by pixel-wise intensity variation and motion trajectory. Benefited from the advanced model and dynamic filtering, the interpolated frame has much better visual quality. Extensive experiments on the natural and synthesized videos demonstrate the superiority of HOMDF over the state-of-the-art methods in both subjective and objective comparisons.

Gas-liquid mass transfer coefficient of methane in bubble column reactor

Energy Technology Data Exchange (ETDEWEB)

Lee, Jaewon; Ha, Kyoung-Su; Lee, Jinwon; Kim, Choongik [Sogang University, Seoul (Korea, Republic of); Yasin, Muhammad; Park, Shinyoung; Chang, In Seop [Gwangju Institute of Science and Technology (GIST), Gwangju (Korea, Republic of); Lee, Eun Yeol [Kyung Hee University, Yongin (Korea, Republic of)

2015-06-15

Biological conversion of methane gas has been attracting considerable recent interest. However, methanotropic bioreactor is limited by low solubility of methane gas in aqueous solution. Although a large mass transfer coefficient of methane in water could possibly overcome this limitation, no dissolved methane probe in aqueous environment is commercially available. We have developed a reactor enabling the measurement of aqueous phase methane concentration and mass transfer coefficient (k{sub L}a). The feasibility of the new reactor was demonstrated by measuring k{sub L}a values as a function of spinning rate of impeller and flow rate of methane gas. Especially, at spinning rate of 300 rpm and flow rate of 3.0 L/min, a large k{sub L}a value of 102.9 h{sup -1} was obtained.

Postoperative Conversion Disorder in Elderly Oral Cancer Patient.

Science.gov (United States)

Yakushiji, Takashi; Hayashi, Kamichika; Morikawa, Takamichi; Migita, Masashi; Ogane, Satoru; Muramatsu, Kyotaro; Kamio, Takashi; Shibahara, Takahiko; Takano, Nobuo

2016-01-01

Conversion disorder is a condition in which psychological stress in response to difficult situations manifests as physical symptoms. Here, we report a case of postoperative coma due to conversion disorder in an elderly oral cancer patient. An 82-year-old woman was referred to Tokyo Dental College Chiba Hospital with a mass lesion on the tongue. A biopsy revealed a well-differentiated squamous cell carcinoma. Surgical treatment was performed for the tongue carcinoma and tracheotomy for management of the airway. On postoperative day 5, the patient exhibited loss of consciousness (Glasgow Coma Scale: E1, VT, M1; Japan Coma Scale: III-300). The patient's vital signs were all normal, as were the results of a full blood count, brain-CT, MRI, and MRA. Only the arm dropping test was positive. Therefore, the cause of the coma was diagnosed as conversion disorder. Seven hours later, the patient showed a complete recovery.

Coefficients calculations of conversion of cancer risk for occupational exposure using Monte Carlo simulations in cardiac procedures of interventionist radiology

International Nuclear Information System (INIS)

Santos, William S.; Neves, Lucio P.; Perini, Ana P.; Caldas, Linda V.E.; Maia, Ana F.

2014-01-01

Cardiac procedures are among the most common procedures in interventional radiology (IR), and can lead to high medical and occupational exposures, as in most cases are procedures complex and long lasting. In this work, conversion coefficients (CC) for the risk of cancer, normalized by kerma area product (KAP) to the patient, cardiologist and nurse were calculated using Monte Carlo simulation. The patient and the cardiologist were represented by anthropomorphic simulators MESH, and the nurse by anthropomorphic phantom FASH. Simulators were incorporated into the code of Monte Carlo MCNPX. Two scenarios were created: in the first (1), lead curtain and protective equipment suspended were not included, and in the second (2) these devices were inserted. The radiographic parameters employed in Monte Carlo simulations were: tube voltage of 60 kVp and 120 kVp; filtration of the beam and 3,5 mmAl beam area of 10 x 10 cm 2 . The average values of CCs to eight projections (in 10 -4 / Gy.cm 2 were 1,2 for the patient, 2,6E-03 (scenario 1) and 4,9E-04 (scenario 2) for cardiologist and 5,2E-04 (scenario 1) and 4,0E-04 (Scenario 2) to the nurse. The results show a significant reduction in CCs for professionals, when the lead curtain and protective equipment suspended are employed. The evaluation method used in this work can provide important information on the risk of cancer patient and professional, and thus improve the protection of workers in cardiac procedures of RI

Spectral effects on some physical coefficients of x-Ray interaction with materials of low atomic number

International Nuclear Information System (INIS)

EL-Kazzaz, S.A.; Youssef, M.; EL-Hadad, S.; and EL-Nadi, L.M.

1988-01-01

X-ray spectra were measured before and after passing through some materials of medical importance applying X-ray diffraction. The mass absorption coefficients of these materials were determined at X-ray peak voltages 27, 30 and 42 kV-p making use the measured spectrum and also by using the direct beam absorption. It has been found that the mass absorption coefficients calculated from the X-ray spectral distribution analysis are in general lower than those obtained considering the direct beam method. From the study of the atomic number and energy dependence of the mass absorption coefficients it has been found that the dependence of the coefficients calculated from the spectral distribution is good agreement with the previously studied data for monoenergetic x-ray beam. Also the roentgen - to - Rad conversion factors were determined at the different used energies and materials. The value of the mass absorption coefficients calculated from the spectral distribution is recommended for use in dose calculation

Analysis on Behaviour of Wavelet Coefficient during Fault Occurrence in Transformer

Science.gov (United States)

Sreewirote, Bancha; Ngaopitakkul, Atthapol

2018-03-01

The protection system for transformer has play significant role in avoiding severe damage to equipment when disturbance occur and ensure overall system reliability. One of the methodology that widely used in protection scheme and algorithm is discrete wavelet transform. However, characteristic of coefficient under fault condition must be analyzed to ensure its effectiveness. So, this paper proposed study and analysis on wavelet coefficient characteristic when fault occur in transformer in both high- and low-frequency component from discrete wavelet transform. The effect of internal and external fault on wavelet coefficient of both fault and normal phase has been taken into consideration. The fault signal has been simulate using transmission connected to transformer experimental setup on laboratory level that modelled after actual system. The result in term of wavelet coefficient shown a clearly differentiate between wavelet characteristic in both high and low frequency component that can be used to further design and improve detection and classification algorithm that based on discrete wavelet transform methodology in the future.

Material-specific Conversion Factors for Different Solid Phantoms Used in the Dosimetry of Different Brachytherapy Sources

Directory of Open Access Journals (Sweden)

Sedigheh Sina

2015-07-01

Full Text Available Introduction Based on Task Group No. 43 (TG-43U1 recommendations, water phantom is proposed as a reference phantom for the dosimetry of brachytherapy sources. The experimental determination of TG-43 parameters is usually performed in water-equivalent solid phantoms. The purpose of this study was to determine the conversion factors for equalizing solid phantoms to water. Materials and Methods TG-43 parameters of low- and high-energy brachytherapy sources (i.e., Pd-103, I-125 and Cs-137 were obtained in different phantoms, using Monte Carlo simulations. The brachytherapy sources were simulated at the center of different phantoms including water, solid water, poly(methyl methacrylate, polystyrene and polyethylene. Dosimetric parameters such as dose rate constant, radial dose function and anisotropy function of each source were compared in different phantoms. Then, conversion factors were obtained to make phantom parameters equivalent to those of water. Results Polynomial coefficients of conversion factors were obtained for all sources to quantitatively compare g(r values in different phantom materials and the radial dose function in water. Conclusion Polynomial coefficients of conversion factors were obtained for all sources to quantitatively compare g(r values in different phantom materials and the radial dose function in water.

Time-differential observation of the ortho-para conversion of liquid D2 under irradiation

International Nuclear Information System (INIS)

Mishima, K.; Utsuro, M.; Nagai, Y.; Tanaka, M.; Kohmoto, T.; Fukuda, Y.; Kiyanagi, Y.; Ooi, M.

2007-01-01

We measured an absolute ortho-D 2 concentration of gas samples taken from irradiated liquid D 2 samples as a function of the integrated radiation dose and the irradiation time by means of a frequency-resolved Raman spectroscopy to study the ortho-D 2 conversion mechanism under irradiation. The measurement was carried out by irradiating liquid ortho-D 2 at a temperature of 25 K with Bremsstrahlung photons, which were produced by bombarding tantalum with 33 MeV electrons, and whose absolute fluxes were determined experimentally by employing a foil activation method. The obtained ortho-D 2 concentration was found to decrease from 98% to 82% monotonically with increasing the radiation dose, irrespective of the electron-beam power. This fact clearly indicates the important role of a radiation-induced breakup effect of the ortho D 2 under the present experimental conditions of radiation dose and irradiation time. The obtained conversion rate is ten times faster than the evaluated value based on an existing model, requiring an alternate mechanism to enhance the conversion

Iodine-124 PET dosimetry in differentiated thyroid cancer: recovery coefficient in 2D and 3D modes for PET(/CT) systems

Energy Technology Data Exchange (ETDEWEB)

Jentzen, Walter; Freudenberg, Lutz; Brandau, Wolfgang; Bockisch, Andreas [Universitaet Duisburg-Essen, Klinik fuer Nuklearmedizin, Essen (Germany); Weise, Reiner; Burchert, Wolfgang [Institut fuer Radiologie, Nuklearmedizin und Molekulare Bildgebung, Herz- und Diabeteszentrum NRW, Bad Oeynhausen (Germany); Kupferschlaeger, Juergen; Bares, Ronald [Universitaet Tuebingen, Klinik fuer Nuklearmedizin, Tuebingen (Germany)

2008-03-15

This study evaluated the absolute quantification of iodine-124 ({sup 124}I) activity concentration with respect to the use of this isotope for dosimetry before therapies with {sup 131}I or {sup 131}I-labeled radiotherapeuticals. The recovery coefficients of positron emission tomography(/computed tomography) PET(/CT) systems using {sup 124}I were determined using phantoms and then validated under typical conditions observed in differentiated thyroid cancer (DTC) patients. Transversal spatial resolution and recovery measurements with {sup 124}I and with fluorine-18 ({sup 18}F) as the reference were performed using isotope-containing line sources embedded in water and six isotope-containing spheres 9.7 to 37.0 mm in diameter placed in water-containing body and cylinder phantoms. The cylinder phantom spheres were filled with {sup 18}F only. Measurements in two-dimensional (2D) and three-dimensional (3D) modes were performed using both stand-alone PET (EXACT HR{sup +}) and combined PET/CT (BIOGRAPH EMOTION DUO) systems. Recovery comparison measurements were additionally performed on a GE ADVANCE PET system using the cylinder phantom. The recovery coefficients were directly determined using the activity concentration of circular regions of interest divided by the prepared activity concentration determined by the dose calibrator. The recovery correction method was validated using three consecutive scans of the body phantom under our {sup 124}I PET(/CT) protocol for DTC patients. Compared with that of {sup 18}F, transversal spatial resolution of {sup 124}I was slightly, but statistically significantly degraded (7.4 mm vs. 8.3 mm, P<0.002). Using the body phantom, recovery was lower for {sup 124}I than for {sup 18}F in both 2D and 3D modes. The {sup 124}I recovery coefficient of the largest sphere was significantly higher in 2D than in 3D mode (81% vs. 75%, P=0.03). Remarkably, the {sup 18}F recovery coefficient for the largest sphere significantly deviated from unity

Quantum mechanical study of the proton exchange in the ortho-para H2 conversion reaction at low temperature.

Science.gov (United States)

Honvault, P; Jorfi, M; González-Lezana, T; Faure, A; Pagani, L

2011-11-14

Ortho-para H(2) conversion reactions mediated by the exchange of a H(+) proton have been investigated at very low energy for the first time by means of a time independent quantum mechanical (TIQM) approach. State-to-state probabilities and cross sections for H(+) + H(2) (v = 0, j = 0,1) processes have been calculated for a collision energy, E(c), ranging between 10(-6) eV and 0.1 eV. Differential cross sections (DCSs) for H(+) + H(2) (v = 0, j = 1) → H(+) + H(2) (v' = 0, j' = 0) for very low energies only start to develop a proper global minimum around the sideways scattering direction (θ≈ 90°) at E(c) = 10(-3) eV. Rate coefficients, a crucial information required for astrophysical models, are provided between 10 K and 100 K. The relaxation ortho-para process j = 1 → j' = 0 is found to be more efficient than the j = 0 → j' = 1 conversion at low temperatures, in line with the extremely small ratio between the ortho and para species of molecular hydrogen predicted at the temperature of interstellar cold molecular clouds. The results obtained by means of a statistical quantum mechanical (SQM) model, which has previously proved to provide an adequate description of the dynamics of the title reactions at a higher collision energy regime, have been compared with the TIQM results. A reasonable good agreement has been found with the only exception of the DCSs for the H(+) + H(2) (v = 0, j = 1) → H(+) + H(2) (v' = 0, j' = 0) process at very low energy. SQM cross sections are also slightly below the quantum results. Estimates for the rate coefficients, in good accord with the TIQM values, are a clear improvement with respect to pioneering statistical studies on the reaction.

Internal conversion in highly stripped 83Kr ions

International Nuclear Information System (INIS)

Copnell, J.; Phillips, W.R.; Barnett, A.R.; Rehm, K.E.; Ahmad, I.; Gehring, J.; Glagola, B.G.; Kutschera, W.

1995-01-01

The total decay probabilities per unit time of the first excited 9.4-keV state in 83 Kr have been measured in ions of ionicity q from 28 to 32. Using a γ-decay probability per unit time of 0.255(2)x10 6 s -1 gives internal conversion coefficients of 14.6(11), 14.9(10), 14.1(9), 14.6(11), and 15.2(24) for q=28--32, respectively. These values are compared with theoretical predictions

Coeficiente de corrección en engranajes cilíndricos como factor de conversión entre sistemas AGMA e ISO. // Addendum modification coefficient as conversion factor of cylindrical gears in AGMA system to ISO standards.

Directory of Open Access Journals (Sweden)

G. González Rey

2007-09-01

Full Text Available A partir de la experiencia de los autores, en trabajos asociados con el análisis para la reconversión de engranajes ensistemas AGMA a partir de herramientas con referencia a normas ISO, en el artículo se pretende exponer las principalesdefiniciones y recomendaciones asociadas al coeficiente de corrección relativo al módulo en engranajes cilíndricos de ejesparalelos con dientes de flanco de evolvente que permitan un racional cálculo de la geometría del engranaje y apreciarmediante ejemplos la ventaja del coeficiente de corrección en la solución de problemas prácticos de conversión deengranajes en sistemas AGMA a ISO.Palabras claves: geometría de engranaje cilíndrico, coeficiente de corrección, conversión AGMA a ISO________________________________________________________________________________AbstractDefinitions and recommendations associated to the addendum modification coefficient are presented. Examples, based onauthor’s experiences in the analysis, recovery and conversion of helical and spur gears in AGMA system to ISO standards showthe advantage of application of the addendum modification coefficient in the solution of practical problems and rationalcalculation of gears.Key words: external parallel-axis cylindrical involute gears, gear geometry, , ISO gear standards, rack shift coefficient x

Meige's Syndrome: Rare Neurological Disorder Presenting as Conversion Disorder.

Science.gov (United States)

Debadatta, Mohapatra; Mishra, Ajay K

2013-07-01

Meige's syndrome is a rare neurological syndrome characterized by oromandibular dystonia and blepharospasm. Its pathophysiology is not clearly determined. A 35-year-old female presented to psychiatric department with blepharospasm and oromandibular dystonia with clinical provisional diagnosis of psychiatric disorder (Conversion Disorder). After thorough physical examination including detailed neurological exam and psychiatric evaluation no formal medical or psychiatric diagnosis could be made. The other differential diagnoses of extra pyramidal symptom, tardive dyskinesia, conversion disorder, anxiety disorder were ruled out by formal diagnostic criteria. Consequently with suspicion of Meige's syndrome she was referred to the department of Neurology and the diagnosis was confirmed. Hence, Meige's syndrome could be misdiagnosed as a psychiatric disorder such as conversion disorder or anxiety disorder because clinical features of Meige's syndrome are highly variable and affected by psychological factors and also can be inhibited voluntarily to some extent.

Critical electrode size in measurement of d33 coefficient of films via spatial distribution of piezoelectric displacement

International Nuclear Information System (INIS)

Wang Zhihong; Miao Jianmin

2008-01-01

Spatial distributions of piezoelectric displacement response across the top electrode have been used in this paper to measure the piezoelectric coefficient d 33 of films based on the converse piezoelectric effect. The technical details and features of a scanning laser Doppler vibrometer have been summarized and discussed for accurately obtaining the spatial displacement distributions. Three definitions, including the apparent, the effective and the constrained piezoelectric coefficient d 33 of films, have been clarified and used to better understand the fundamental phenomenon behind the measured displacement distributions. Finite element analysis reveals that both the apparent and the effective piezoelectric coefficients depend on the electrode radius of test capacitor as well as film thickness. However, there exists a critical electrode size for apparent piezoelectric coefficients and a critical test capacitor aspect ratio for effective piezoelectric coefficient. Beyond their respective critical values, both coefficients converge to the constrained piezoelectric coefficient irrespective of film thickness. The finding of the critical electric size makes it possible to consistently measure the constrained piezoelectric coefficient of films by using the spatial distributions of the piezoelectric displacement response and becomes the fundamental criterion of this measurement method

Introduction to linear systems of differential equations

CERN Document Server

Adrianova, L Ya

1995-01-01

The theory of linear systems of differential equations is one of the cornerstones of the whole theory of differential equations. At its root is the concept of the Lyapunov characteristic exponent. In this book, Adrianova presents introductory material and further detailed discussions of Lyapunov exponents. She also discusses the structure of the space of solutions of linear systems. Classes of linear systems examined are from the narrowest to widest: 1)�autonomous, 2)�periodic, 3)�reducible to autonomous, 4)�nearly reducible to autonomous, 5)�regular. In addition, Adrianova considers the following: stability of linear systems and the influence of perturbations of the coefficients on the stability the criteria of uniform stability and of uniform asymptotic stability in terms of properties of the solutions several estimates of the growth rate of solutions of a linear system in terms of its coefficients How perturbations of the coefficients change all the elements of the spectrum of the system is defin...

Hierarchically structured exergetic and exergoeconomic analysis and evaluation of energy conversion processes

International Nuclear Information System (INIS)

Hebecker, Dietrich; Bittrich, Petra; Riedl, Karsten

2005-01-01

Evaluation of the efficiency and economic benefit of energy conversion processes and technologies requires a scientifically based analysis. The hierarchically structured exergetic analysis provides a detailed characterization of complex technical systems. By defining corresponding evaluation coefficients, the exergetic efficiency can be assessed for units within the whole system. Based on this exergetic analysis, a thermoeconomic evaluation method is developed. A cost function is defined for all units, subsystems and the total plant, so that the cost flow in the system can be calculated. Three dimensionless coefficients, the Pauer factor, the loss coefficient and the cost factor, enable pinpointing cost intensive process units, allocating cost in cases of co-production and gaining insight for future design improvements. The methodology is demonstrated by a biomass gasification plant producing electricity, heat and cold

Schwarz maps of algebraic linear ordinary differential equations

Science.gov (United States)

Sanabria Malagón, Camilo

2017-12-01

A linear ordinary differential equation is called algebraic if all its solution are algebraic over its field of definition. In this paper we solve the problem of finding closed form solution to algebraic linear ordinary differential equations in terms of standard equations. Furthermore, we obtain a method to compute all algebraic linear ordinary differential equations with rational coefficients by studying their associated Schwarz map through the Picard-Vessiot Theory.

Determination of the Peltier Coefficient of Germanium in a Vertical Bridgeman-Stockbarger Furnace

Science.gov (United States)

Weigel, Michaela E. K.; Matthiesen, David H.

1997-01-01

The Peltier effect is the fundamental mechanism that makes interface demarcation through current pulsing possible. If a method for calculating the necessary current density for effective demarcation is to be developed, it will be necessary to know the value of the Peltier coefficient. This study determined experimentally the value of the Peltier coefficient for gallium-doped germanium by comparing the change in average growth rates between current-on and current-off periods. Current-on and current-off layer thickness measurements were made using differential interference contrast microscopy and atomic force microscopy. It was found that the Joule and Thomson effects could not be neglected. Peltier coefficients calculated from the experimental data with an analysis that accounts for Joule, Thomson, and Peltier effects yielded an average value for the Peltier coefficient of 0.076 +/- 0.015 V.

[Diagnostic efficiency of decline rate of signal intensity and apparent diffusion coefficient with different b values for differentiating benign and malignant breast lesions on diffusion-weighted 3.0T magnetic resonance imaging].

Science.gov (United States)

Jiang, Jing; Liu, Wanhua; Ye, Yuanyuan; Wang, Rui; Li, Fengfang; Peng, Chengyu

2014-06-17

To investigate the diagnostic efficiency of decline rate of signal intensity and apparent diffusion coefficient with different b values for differentiating benign and malignant breast lesions on diffusion-weighted 3.0 T magnetic resonance imaging. A total of 152 patients with 162 confirmed histopathologically breast lesions (85 malignant and 77 benign) underwent 3.0 T diffusion-weighted magnetic resonance imaging. Four b values (0, 400, 800 and 1 000 s/mm²) were used. The signal intensity and ADC values of breast lesions were measured respectively. The signal intensity decline rate (SIDR) and apparent diffusion coefficient decline rate (ADCDR) were calculated respectively. SIDR = (signal intensity of lesions with low b value-signal intensity of lesions with high b value)/signal intensity of lesions with low b value, ADCDR = (ADC value of lesions with low b value-ADC value of lesions with high b value) /ADC value of lesions with low b value. The independent sample t-test was employed for statistical analyses and the receiver operating characteristic (ROC) curve for evaluating the diagnosis efficiency of SIDR and ADCDR values. Significant differences were observed in SIDR between benign and malignant breast lesions with b values of 0-400, 400-800 and 800-1 000 s/mm². The sensitivities of SIDR for differentiating benign and malignant breast lesions were 61.2%, 68.2% and 67.1%, the specificities 74.0%, 85.7% and 67.5%, the diagnosis accordance rates 67.3%, 76.5% and 67.3%, the positive predictive values 72.2%, 84.1% and 69.5% and the negative predictive values 63.3%, 71.0% and 65.0% respectively. Significant differences were observed in ADCDR between benign and malignant breast lesions with b values of 400-800 s/mm² and 800-1 000 s/mm². The sensitivities of SDR for differentiating benign and malignant breast lesions were 80.0% and 65.9%, the specificities 72.7% and 65.0%, the diagnostic accordance rates 76.5% and 65.4%, the positive predictive values 76.4% and 67

Ultra-high-speed wavelength conversion in a silicon photonic chip

DEFF Research Database (Denmark)

Hu, Hao; Ji, Hua; Galili, Michael

2011-01-01

We have successfully demonstrated all-optical wavelength conversion of a 640-Gbit/s line-rate return-to-zero differential phase-shift keying (RZ-DPSK) signal based on low-power four wave mixing (FWM) in a silicon photonic chip with a switching energy of only ~110 fJ/bit. The waveguide dispersion...... of the silicon nanowire is nano-engineered to optimize phase matching for FWM and the switching power used for the signal processing is low enough to reduce nonlinear absorption from twophoton- absorption (TPA). These results demonstrate that high-speed wavelength conversion is achievable in silicon chips...

INTERNAL-CYCLE VARIATION OF SOLAR DIFFERENTIAL ROTATION

International Nuclear Information System (INIS)

Li, K. J.; Xie, J. L.; Shi, X. J.

2013-01-01

The latitudinal distributions of the yearly mean rotation rates measured by Suzuki in 1998 and 2012 and Pulkkinen and Tuominen in 1998 are utilized to investigate internal-cycle variation of solar differential rotation. The rotation rate at the solar equator seems to have decreased since cycle 10 onward. The coefficient B of solar differential rotation, which represents the latitudinal gradient of rotation, is found to be smaller in the several years after the minimum of a solar cycle than in the several years after the maximum time of the cycle, and it peaks several years after the maximum time of the solar cycle. The internal-cycle variation of the solar rotation rates looks similar in profile to that of the coefficient B. A new explanation is proposed to address such a solar-cycle-related variation of the solar rotation rates. Weak magnetic fields may more effectively reflect differentiation at low latitudes with high rotation rates than at high latitudes with low rotation rates, and strong magnetic fields may more effectively repress differentiation at relatively low latitudes than at high latitudes. The internal-cycle variation is inferred as the result of both the latitudinal migration of the surface torsional pattern and the repression of strong magnetic activity in differentiation.

Towards spontaneous parametric down-conversion at low temperatures

Directory of Open Access Journals (Sweden)

Akatiev Dmitrii

2017-01-01

Full Text Available The possibility of observing spontaneous parametric down-conversion in doped nonlinear crystals at low temperatures, which would be useful for combining heralded single-photon sources and quantum memories, is studied theoretically. The ordinary refractive index of a lithium niobate crystal doped with magnesium oxide LiNbO3:MgO is measured at liquid nitrogen and helium temperatures. On the basis of the experimental data, the coefficients of the Sellmeier equation are determined for the temperatures from 5 to 300 K. In addition, a poling period of the nonlinear crystal has been calculated for observing type-0 spontaneous parametric down-conversion (ooo-synchronism at the liquid helium temperature under pumping at the wavelength of λp = 532 nm and emission of the signal field at the wavelength of λs = 794 nm, which corresponds to the resonant absorption line of Tm3+ doped ions.

Diagnostic accuracy of apparent diffusion coefficient and 123I-metaiodobenzylguanidine for differentiation of multiple system atrophy and Parkinson's disease.

Directory of Open Access Journals (Sweden)

Atsushi Umemura

Full Text Available BACKGROUND: It is often hard to differentiate Parkinson's disease (PD and parkinsonian variant of multiple system atrophy (MSA-P, especially in the early stages. Cardiac sympathetic denervation and putaminal rarefaction are specific findings for PD and MSA-P, respectively. PURPOSE: We investigated diagnostic accuracy of putaminal apparent diffusion coefficient (ADC test for MSA-P and (123I-metaiodobenzylguanidine (MIBG scintigram for PD, especially in early-stage patients. METHODS: The referral standard diagnosis of PD and MSA-P were the diagnostic criteria of the United Kingdom Parkinson's Disease Society Brain Bank Criteria and the second consensus criteria, respectively. Based on the referral standard criteria, diagnostic accuracy [area under the receiver-operator characteristic curve (AUC, sensitivity and specificity] of the ADC and MIBG tests was estimated retrospectively. Diagnostic accuracy of these tests performed within 3 years of symptom onset was also investigated. RESULTS: ADC and MIBG tests were performed on 138 patients (20 MSA and 118 PD. AUC was 0.95 and 0.83 for the ADC and MIBG tests, respectively. Sensitivity and specificity were 85.0% and 89.0% for MSA-P diagnosis by ADC test and 67.0% and 80.0% for PD diagnosis by MIBG test. When these tests were restricted to patients with disease duration ≤ 3 years, the sensitivity and specificity were 75.0% and 91.4% for the ADC test (MSA-P diagnosis and 47.7% and 92.3% for the MIBG test (PD diagnosis. CONCLUSIONS: Both tests were useful in differentiating between PD and MSA-P, even in the early stages. In early-stage patients, elevated putaminal ADC was a diagnostic marker for MSA-P. Despite high specificity of the MIBG test, careful neurological history and examinations were required for PD diagnosis because of possible false-negative results.

Diagnostic accuracy of apparent diffusion coefficient and 123I-metaiodobenzylguanidine for differentiation of multiple system atrophy and Parkinson's disease.

Science.gov (United States)

Umemura, Atsushi; Oeda, Tomoko; Hayashi, Ryutaro; Tomita, Satoshi; Kohsaka, Masayuki; Yamamoto, Kenji; Sawada, Hideyuki

2013-01-01

It is often hard to differentiate Parkinson's disease (PD) and parkinsonian variant of multiple system atrophy (MSA-P), especially in the early stages. Cardiac sympathetic denervation and putaminal rarefaction are specific findings for PD and MSA-P, respectively. We investigated diagnostic accuracy of putaminal apparent diffusion coefficient (ADC) test for MSA-P and (123)I-metaiodobenzylguanidine (MIBG) scintigram for PD, especially in early-stage patients. The referral standard diagnosis of PD and MSA-P were the diagnostic criteria of the United Kingdom Parkinson's Disease Society Brain Bank Criteria and the second consensus criteria, respectively. Based on the referral standard criteria, diagnostic accuracy [area under the receiver-operator characteristic curve (AUC), sensitivity and specificity] of the ADC and MIBG tests was estimated retrospectively. Diagnostic accuracy of these tests performed within 3 years of symptom onset was also investigated. ADC and MIBG tests were performed on 138 patients (20 MSA and 118 PD). AUC was 0.95 and 0.83 for the ADC and MIBG tests, respectively. Sensitivity and specificity were 85.0% and 89.0% for MSA-P diagnosis by ADC test and 67.0% and 80.0% for PD diagnosis by MIBG test. When these tests were restricted to patients with disease duration ≤ 3 years, the sensitivity and specificity were 75.0% and 91.4% for the ADC test (MSA-P diagnosis) and 47.7% and 92.3% for the MIBG test (PD diagnosis). Both tests were useful in differentiating between PD and MSA-P, even in the early stages. In early-stage patients, elevated putaminal ADC was a diagnostic marker for MSA-P. Despite high specificity of the MIBG test, careful neurological history and examinations were required for PD diagnosis because of possible false-negative results.

On Robust Stability of Differential-Algebraic Equations with Structured Uncertainty

Directory of Open Access Journals (Sweden)

A. Kononov

2018-03-01

Full Text Available We consider a linear time-invariant system of differential-algebraic equations (DAE, which can be written as a system of ordinary differential equations with non-invertible coefficients matrices. An important characteristic of DAE is the unsolvability index, which reflects the complexity of the internal structure of the system. The question of the asymptotic stability of DAE containing the uncertainty given by the matrix norm is investigated. We consider a perturbation in the structured uncertainty case. It is assumed that the initial nominal system is asymptotically stable. For the analysis, the original equation is reduced to the structural form, in which the differential and algebraic subsystems are separated. This structural form is equivalent to the input system in the sense of coincidence of sets of solutions, and the operator transforming the DAE into the structural form possesses the inverse operator. The conversion to structural form does not use a change of variables. Regularity of matrix pencil of the source equation is the necessary and sufficient condition of structural form existence. Sufficient conditions have been obtained that perturbations do not break the internal structure of the nominal system. Under these conditions robust stability of the DAE with structured uncertainty is investigated. Estimates for the stability radius of the perturbed DAE system are obtained. The text of the article is from the simpler case, in which the perturbation is present only for an unknown function, to a more complex one, under which the perturbation is also present in the derivative of the unknown function. We used values of the real and the complex stability radii of explicit ordinary differential equations for obtaining the results. We consider the example illustrating the obtained results.

Monte Carlo calculation of the nuclear temperature coefficient in fast reactors

Energy Technology Data Exchange (ETDEWEB)

Matthes, W.

1974-04-15

A Monte Carlo program for the calculation of the nuclear temperature coefficient for fast reactors is described. The special difficulties for this problem are the energy and space dependence of the cross sections and the calculation of differential eifects. These difficulties are discussed in detail and the way for their solution chosen in this program is described. (auth)

Differential discriminator

International Nuclear Information System (INIS)

Dukhanov, V.I.; Mazurov, I.B.

1981-01-01

A principal flowsheet of a differential discriminator intended for operation in a spectrometric circuit with statistical time distribution of pulses is described. The differential discriminator includes four integrated discriminators and a channel of piled-up signal rejection. The presence of the rejection channel enables the discriminator to operate effectively at loads of 14x10 3 pulse/s. The temperature instability of the discrimination thresholds equals 250 μV/ 0 C. The discrimination level changes within 0.1-5 V, the level shift constitutes 0.5% for the filling ratio of 1:10. The rejection coefficient is not less than 90%. Alpha spectrum of the 228 Th source is presented to evaluate the discriminator operation with the rejector. The rejector provides 50 ns time resolution

A conversion method of air-kerma from the primary, scatter and leakage radiations to ambient dose equivalent for calculating the mamography x-ray shielding barrier

International Nuclear Information System (INIS)

Kharrati, H.

2005-01-01

The primary, scatter, and leakage doses(in Gy), which constitute the data base for calculating shielding requirements for x-ray facilities, are often converted to the equivalent dose (in sievert) by using a constant of conversion of 1.145Sv/Gy. This constant is used for diagnostic radiology as well as for mammography spectra, and is derived by considering an exposure of 1 R corresponds to an air kerma of 8.73 m Gy, which renders by tradition an equivalent dose of 10 mSv. However, this conversion does not take into account the energy dependence of the conversion coefficients relating air kerma to the equivalent dose as described in ICRU report. Moreover, current radiation protection standards propose the use of the quantity ambient dose equivalent in order to qualify the efficiently of given radiation shielding. Therefore, in this study, a new approach has been introduced for derivation ambient dose equivalent from air kerma to calculate shielding requirements in mammography facilities. This new approach has been used to compute the conversion coefficients relating air kerma to ambient dose equivalent for mammography reference beam series of the Netherlands Metrology Institute Van Swinden Laboratorium (NMi), National Institute of Standards and Technology (NIST), and International Atomic Energy Agency (AIEA) laboratories. The calculation has been performed by the means of two methods which show a maximum deviation less than 10%2 for the primary, scatter, and leakage radiations. The results show that the conversion coefficients vary from 0.242 Sv/ Gy to 0.692 Sv/Gy with an average value of 0.436 Sv/Gy for the primary and the scatter radiations, and form 0.156 Sv/Gy to 1.329 Sv/Gy with an average value of 0.98 Sv/Gy for the leakage radiation. Simpkin et al. using an empirical approach propose a conversion value of 0.50 Sv/Gy for the mammography x-ray spectra. This value approximately coincides with the average conversion value of 0.436 Sv/Gy obtained in this work for

Wind turbine power coefficient estimation by soft computing methodologies: Comparative study

International Nuclear Information System (INIS)

Shamshirband, Shahaboddin; Petković, Dalibor; Saboohi, Hadi; Anuar, Nor Badrul; Inayat, Irum; Akib, Shatirah; Ćojbašić, Žarko; Nikolić, Vlastimir; Mat Kiah, Miss Laiha; Gani, Abdullah

2014-01-01

Highlights: • Variable speed operation of wind turbine to increase power generation. • Changeability and fluctuation of wind has to be accounted. • To build an effective prediction model of wind turbine power coefficient. • The impact of the variation in the blade pitch angle and tip speed ratio. • Support vector regression methodology application as predictive methodology. - Abstract: Wind energy has become a large contender of traditional fossil fuel energy, particularly with the successful operation of multi-megawatt sized wind turbines. However, reasonable wind speed is not adequately sustainable everywhere to build an economical wind farm. In wind energy conversion systems, one of the operational problems is the changeability and fluctuation of wind. In most cases, wind speed can vacillate rapidly. Hence, quality of produced energy becomes an important problem in wind energy conversion plants. Several control techniques have been applied to improve the quality of power generated from wind turbines. In this study, the polynomial and radial basis function (RBF) are applied as the kernel function of support vector regression (SVR) to estimate optimal power coefficient value of the wind turbines. Instead of minimizing the observed training error, SVR p oly and SVR r bf attempt to minimize the generalization error bound so as to achieve generalized performance. The experimental results show that an improvement in predictive accuracy and capability of generalization can be achieved by the SVR approach in compare to other soft computing methodologies

Informed Conjecturing of Solutions for Differential Equations in a Modeling Context

Science.gov (United States)

Winkel, Brian

2015-01-01

We examine two differential equations. (i) first-order exponential growth or decay; and (ii) second order, linear, constant coefficient differential equations, and show the advantage of learning differential equations in a modeling context for informed conjectures of their solution. We follow with a discussion of the complete analysis afforded by…

Histogram analysis of apparent diffusion coefficient maps for differentiating primary CNS lymphomas from tumefactive demyelinating lesions.

Science.gov (United States)

Lu, Shan Shan; Kim, Sang Joon; Kim, Namkug; Kim, Ho Sung; Choi, Choong Gon; Lim, Young Min

2015-04-01

This study intended to investigate the usefulness of histogram analysis of apparent diffusion coefficient (ADC) maps for discriminating primary CNS lymphomas (PCNSLs), especially atypical PCNSLs, from tumefactive demyelinating lesions (TDLs). Forty-seven patients with PCNSLs and 18 with TDLs were enrolled in our study. Hyperintense lesions seen on T2-weighted images were defined as ROIs after ADC maps were registered to the corresponding T2-weighted image. ADC histograms were calculated from the ROIs containing the entire lesion on every section and on a voxel-by-voxel basis. The ADC histogram parameters were compared among all PCNSLs and TDLs as well as between the subgroup of atypical PCNSLs and TDLs. ROC curves were constructed to evaluate the diagnostic performance of the histogram parameters and to determine the optimum thresholds. The differences between the PCNSLs and TDLs were found in the minimum ADC values (ADCmin) and in the 5th and 10th percentiles (ADC5% and ADC10%) of the cumulative ADC histograms. However, no statistical significance was found in the mean ADC value or in the ADC value concerning the mode, kurtosis, and skewness. The ADCmin, ADC5%, and ADC10% were also lower in atypical PCNSLs than in TDLs. ADCmin was the best indicator for discriminating atypical PCNSLs from TDLs, with a threshold of 556×10(-6) mm2/s (sensitivity, 81.3 %; specificity, 88.9%). Histogram analysis of ADC maps may help to discriminate PCNSLs from TDLs and may be particularly useful in differentiating atypical PCNSLs from TDLs.

Exponentially Convergent Algorithms for Abstract Differential Equations

CERN Document Server

Gavrilyuk, Ivan; Vasylyk, Vitalii

2011-01-01

This book presents new accurate and efficient exponentially convergent methods for abstract differential equations with unbounded operator coefficients in Banach space. These methods are highly relevant for the practical scientific computing since the equations under consideration can be seen as the meta-models of systems of ordinary differential equations (ODE) as well as the partial differential equations (PDEs) describing various applied problems. The framework of functional analysis allows one to obtain very general but at the same time transparent algorithms and mathematical results which

Rarefied-flow pitching moment coefficient measurements of the Shuttle Orbiter

Science.gov (United States)

Blanchard, R. C.; Hinson, E. W.

1988-01-01

An overview of the process for obtaining the Shuttle Orbiter rarefied-flow pitching moment from flight gyro data is presented. The extraction technique involves differentiation of the output of the pitch gyro after accounting for nonaerodynamic torques, such as those produced by gravity gradient and the Orbiter's auxiliary power unit and adjusting for drift biases. The overview of the extraction technique includes examples of results from each of the steps involved in the process, using the STS-32 mission as a typical sample case. The total pitching moment and moment coefficient (Cm) for that flight are calculated and compared with preflight predictions. The flight results show the anticipated decrease in Cm with increasing altitude. However, the total moment coefficient is less than predicted using preflight estimates.

Territorial differentiation of incomes adjusted for inflation

Directory of Open Access Journals (Sweden)

Marina Valeryevna, Moroshkina

2017-06-01

Full Text Available Objective to analyze and evaluate the regional disparities of socioeconomic development of the Russian regions in terms of income differentiation adjusted for the level of inflation. Methods indicator by which to measure the level of regional growth heterogeneity is Gini coefficient allowing to determine the degree of the Russian regionsrsquo deviation from absolute equality. The unique feature of the authorrsquos approach is the calculation and analysis of the Gini coefficient not only in current prices but also in comparable prices of 1991. Thus the comparison of the Gini coefficient in terms of quotper capita incomequot in the period from 1991 to 2013 in comparable and current prices allows to estimate the impact of changes in the prices level on the dynamics of regional development. Results the article states that the regions differentiation by the level of economic development determines the necessity of considering this factor in economic policy areas. In these circumstances the analysis of income differentiation of the Russian regions has to take the impact of inflation into account. The article reviews the Russian and foreign research in the sphere of the income differentiation. Significant scientific interest to the problem of regional inequality is obvious over the past several decades. Approaches and methods of assessing the level of regional disparities are systematized as well as its key performance indicators. To assess the level of differentiation of Russian regions we used the Gini coefficient which was calculated not only by current but also by comparable prices. The calculation was carried out basing on the recalculation of the per capita income using the consumer price index. In the framework of the analysis the calculated Gini coefficient for per capita income by current and integrated prices allowed to observe the differential behavior of this indicator. In terms of quotper capita incomequot by current prices there is a

Complex centers of polynomial differential equations

Directory of Open Access Journals (Sweden)

Mohamad Ali M. Alwash

2007-07-01

Full Text Available We present some results on the existence and nonexistence of centers for polynomial first order ordinary differential equations with complex coefficients. In particular, we show that binomial differential equations without linear terms do not have complex centers. Classes of polynomial differential equations, with more than two terms, are presented that do not have complex centers. We also study the relation between complex centers and the Pugh problem. An algorithm is described to solve the Pugh problem for equations without complex centers. The method of proof involves phase plane analysis of the polar equations and a local study of periodic solutions.

Runge-Kutta Methods for Linear Ordinary Differential Equations

Science.gov (United States)

Zingg, David W.; Chisholm, Todd T.

1997-01-01

Three new Runge-Kutta methods are presented for numerical integration of systems of linear inhomogeneous ordinary differential equations (ODES) with constant coefficients. Such ODEs arise in the numerical solution of the partial differential equations governing linear wave phenomena. The restriction to linear ODEs with constant coefficients reduces the number of conditions which the coefficients of the Runge-Kutta method must satisfy. This freedom is used to develop methods which are more efficient than conventional Runge-Kutta methods. A fourth-order method is presented which uses only two memory locations per dependent variable, while the classical fourth-order Runge-Kutta method uses three. This method is an excellent choice for simulations of linear wave phenomena if memory is a primary concern. In addition, fifth- and sixth-order methods are presented which require five and six stages, respectively, one fewer than their conventional counterparts, and are therefore more efficient. These methods are an excellent option for use with high-order spatial discretizations.

An Analytical Solution for Transient Heat Conduction in a Composite Slab with Time-Dependent Heat Transfer Coefficient

Directory of Open Access Journals (Sweden)

Ryoichi Chiba

2018-01-01

Full Text Available An analytical solution is derived for one-dimensional transient heat conduction in a composite slab consisting of n layers, whose heat transfer coefficient on an external boundary is an arbitrary function of time. The composite slab, which has thermal contact resistance at n-1 interfaces, as well as an arbitrary initial temperature distribution and internal heat generation, convectively exchanges heat at the external boundaries with two different time-varying surroundings. To obtain the analytical solution, the shifting function method is first used, which yields new partial differential equations under conventional types of external boundary conditions. The solution for the derived differential equations is then obtained by means of an orthogonal expansion technique. Numerical calculations are performed for two composite slabs, whose heat transfer coefficient on the heated surface is either an exponential or a trigonometric function of time. The numerical results demonstrate the effects of temporal variations in the heat transfer coefficient on the transient temperature field of composite slabs.

Monopole conversion hidden by penetration effect in magnetic dipole transitions

International Nuclear Information System (INIS)

Bikit, I.; Anichin, I.; Marinkov, L.

1977-01-01

The 191 keV 197 Au nad 340 keV 233 U transitions are investigated and the effect of penetration into the M1-component is accounted for. Theoretical internal conversion coefficients (ICC) and electron parameters to account for the penetration effect have been obtained by interpolating the data of the Hager and Zeltzer tables. The ICC values and ratios are analyzed under the assumption that the 191 keV 197 Au transition has multipolarities M1 + E2 and E 0 +M1. A common overlapping occurs when the nuclear penetration parameter lambda for magnetic dipole transition is lambda = 34.2+-2.2. For the 340 keV 233 U transition the ICC has been found to equal αk=0.69+-0.07, and the relative conversion-line intensities have been determined. It is concluded that the 191 keV 197 Au nad 340 keV 233 U transitions involve an electric monopole component concealed by the penetration effect in the M1-conversion. The matrix elements of the E0-transition have been evaluated

Comparison of four large-eddy simulation research codes and effects of model coefficient and inflow turbulence in actuator-line-based wind turbine modeling

DEFF Research Database (Denmark)

Martínez-Tossas, Luis A.; Churchfield, Matthew J.; Yilmaz, Ali Emre

2018-01-01

to match closely for all codes. The value of the Smagorinsky coefficient in the subgrid-scale turbulence model is shown to have a negligible effect on the time-averaged loads along the blades. Conversely, the breakdown location of the wake is strongly dependent on the Smagorinsky coefficient in uniform...... coefficient has a negligible effect on the wake profiles. It is concluded that for LES of wind turbines and wind farms using ALM, careful implementation and extensive cross-verification among codes can result in highly reproducible predictions. Moreover, the characteristics of the inflow turbulence appear...

Perturbative methods applied for sensitive coefficients calculations in thermal-hydraulic systems

International Nuclear Information System (INIS)

Andrade Lima, F.R. de

1993-01-01

The differential formalism and the Generalized Perturbation Theory (GPT) are applied to sensitivity analysis of thermal-hydraulics problems related to pressurized water reactor cores. The equations describing the thermal-hydraulic behavior of these reactors cores, used in COBRA-IV-I code, are conveniently written. The importance function related to the response of interest and the sensitivity coefficient of this response with respect to various selected parameters are obtained by using Differential and Generalized Perturbation Theory. The comparison among the results obtained with the application of these perturbative methods and those obtained directly with the model developed in COBRA-IV-I code shows a very good agreement. (author)

Novel Design of Recursive Differentiator Based on Lattice Wave Digital Filter

Directory of Open Access Journals (Sweden)

R. Barsainya

2017-04-01

Full Text Available In this paper, a novel design of third and fifth order differentiator based on lattice wave digital filter (LWDF, established on optimizing L_1-error approximation function using cuckoo search algorithm (CSA is proposed. We present a novel realization of minimum multiplier differentiator using LWD structure leading to requirement of optimizing only N coefficients for Nth order differentiator. The gamma coefficients of lattice wave digital differentiator (LWDD are computed by minimizing the L_1-norm fitness function leading to a flat response. The superiority of the proposed LWDD is evident by comparing it with other differentiators mentioned in the literature. The magnitude response of the designed LWDD is found to be of high accuracy with flat response in a wide frequency range. The simulation and statistical results validates that the designed minimum multiplier LWDD circumvents the existing one in terms of minimum absolute magnitude error, mean relative error (dB and efficient structural realization, thereby making the proposed LWDD a promising approach to digital differentiator design.

Exponential convergence for a class of delayed cellular neural networks with time-varying coefficients

International Nuclear Information System (INIS)

Liu Bingwen

2008-01-01

In this Letter, we consider a class of delayed cellular neural networks with time-varying coefficients. By applying Lyapunov functional method and differential inequality techniques, we establish new results to ensure that all solutions of the networks converge exponentially to zero point

Linear-quadratic control and quadratic differential forms for multidimensional behaviors

NARCIS (Netherlands)

Napp, D.; Trentelman, H.L.

2011-01-01

This paper deals with systems described by constant coefficient linear partial differential equations (nD-systems) from a behavioral point of view. In this context we treat the linear-quadratic control problem where the performance functional is the integral of a quadratic differential form. We look

Quasi-Newton methods for parameter estimation in functional differential equations

Science.gov (United States)

Brewer, Dennis W.

1988-01-01

A state-space approach to parameter estimation in linear functional differential equations is developed using the theory of linear evolution equations. A locally convergent quasi-Newton type algorithm is applied to distributed systems with particular emphasis on parameters that induce unbounded perturbations of the state. The algorithm is computationally implemented on several functional differential equations, including coefficient and delay estimation in linear delay-differential equations.

Differentiating between Glioblastoma and Primary CNS Lymphoma Using Combined Whole-tumor Histogram Analysis of the Normalized Cerebral Blood Volume and the Apparent Diffusion Coefficient.

Science.gov (United States)

Bao, Shixing; Watanabe, Yoshiyuki; Takahashi, Hiroto; Tanaka, Hisashi; Arisawa, Atsuko; Matsuo, Chisato; Wu, Rongli; Fujimoto, Yasunori; Tomiyama, Noriyuki

2018-05-31

This study aimed to determine whether whole-tumor histogram analysis of normalized cerebral blood volume (nCBV) and apparent diffusion coefficient (ADC) for contrast-enhancing lesions can be used to differentiate between glioblastoma (GBM) and primary central nervous system lymphoma (PCNSL). From 20 patients, 9 with PCNSL and 11 with GBM without any hemorrhagic lesions, underwent MRI, including diffusion-weighted imaging and dynamic susceptibility contrast perfusion-weighted imaging before surgery. Histogram analysis of nCBV and ADC from whole-tumor voxels in contrast-enhancing lesions was performed. An unpaired t-test was used to compare the mean values for each type of tumor. A multivariate logistic regression model (LRM) was performed to classify GBM and PCNSL using the best parameters of ADC and nCBV. All nCBV histogram parameters of GBMs were larger than those of PCNSLs, but only average nCBV was statistically significant after Bonferroni correction. Meanwhile, ADC histogram parameters were also larger in GBM compared to those in PCNSL, but these differences were not statistically significant. According to receiver operating characteristic curve analysis, the nCBV average and ADC 25th percentile demonstrated the largest area under the curve with values of 0.869 and 0.838, respectively. The LRM combining these two parameters differentiated between GBM and PCNSL with a higher area under the curve value (Logit (P) = -21.12 + 10.00 × ADC 25th percentile (10 -3 mm 2 /s) + 5.420 × nCBV mean, P histogram analysis of nCBV and ADC combined can be a valuable objective diagnostic method for differentiating between GBM and PCNSL.

Nuclear data for the calculation of thermal reactor reactivity coefficients

International Nuclear Information System (INIS)

1989-01-01

On its 15th meeting in Vienna, 16-20 June 1986, the International Nuclear Data Committee (INDC) considered it important to review the accuracy with which changes in thermal reactor reactivity resulting from changes in temperature and coolant density can be predicted. It was noted that reactor physicists in several countries had to adjust the thermal neutron cross-section data base in order to reproduce measured reactivity coefficients. Consequently, it appeared to be essential to examine the consistency of the integral and differential cross-section data and to make all the information available which has a bearing on reactivity coefficient prediction. Following the recommendation of the INDC, the Nuclear Data Section of the International Atomic Energy Agency, therefore, convened the Advisory Group Meeting on Nuclear Data for the Calculation of Thermal Reaction Reactivity Coefficients, in Vienna, Austria, 7-10 Dec. 1987. The Conclusions and Recommendations of the meeting together with the papers presented, are submitted in the present document. A separate abstract was prepared for each of these 12 papers. Refs, figs and tabs

Comparison of conversion coefficients for equivalent dose in terms of air kerma for photons using a male adult voxel simulator in sitting and standing posture with geometry of irradiation antero-posterior

International Nuclear Information System (INIS)

Galeano, D.C.; Cavalcante, F.R.; Carvalho, A.B.; Hunt, J.

2014-01-01

The dose conversion coefficient (DCC) is important to quantify and assess effective doses associated with medical, professional and public exposures. The calculation of DCCs using anthropomorphic simulators and radiation transport codes is justified since in-vivo measurement of effective dose is extremely difficult and not practical for occupational dosimetry. DCCs have been published by the ICRP using simulators in a standing posture, which is not always applicable to all exposure scenarios, providing an inaccurate dose estimation. The aim of this work was to calculate DCCs for equivalent dose in terms of air kerma (H/Kair) using the Visual Monte Carlo (VMC) code and the VOXTISS8 adult male voxel simulator in sitting and standing postures. In both postures, the simulator was irradiated by a plane source of monoenergetic photons in antero-posterior (AP) geometry. The photon energy ranged from 15 keV to 2 MeV. The DCCs for both postures were compared and the DCCs for the standing simulator were higher. For certain organs, the difference of DCCs were more significant, as in gonads (48% higher), bladder (16% higher) and colon (11% higher). As these organs are positioned in the abdominal region, the posture of the anthropomorphic simulator modifies the form in which the radiation is transported and how the energy is deposited. It was also noted that the average percentage difference of conversion coefficients was 33% for the bone marrow, 11% for the skin, 13% for the bone surface and 31% for the muscle. For other organs, the percentage difference of the DCCs for both postures was not relevant (less than 5%) due to no anatomical changes in the organs of the head, chest and upper abdomen. We can conclude that is important to obtain DCCs using different postures from those present in the scientific literature. - Highlights: • Scenarios of external photon exposures were performed in VMC code. • The VOXTISS8 simulator was irradiated in standing and sitting postures. �

Discharge Coefficient of Rectangular Short-Crested Weir with Varying Slope Coefficients

Directory of Open Access Journals (Sweden)

Yuejun Chen

2018-02-01

Full Text Available Rectangular short-crested weirs are widely used for simple structure and high discharge capacity. As one of the most important and influential factors of discharge capacity, side slope can improve the hydraulic characteristics of weirs at special conditions. In order to systemically study the effects of upstream and downstream slope coefficients S1 and S2 on overflow discharge coefficient in a rectangular short-crested weir the Volume of Fluid (VOF method and the Renormalization Group (RNG κ-ε turbulence model are used. In this study, the slope coefficient ranges from V to 3H:1V and each model corresponds to five total energy heads of H0 ranging from 8.0 to 24.0 cm. Comparisons of discharge coefficients and free surface profiles between simulated and laboratory results display a good agreement. The simulated results show that the difference of discharge coefficients will decrease with upstream slopes and increase with downstream slopes as H0 increases. For a given H0, the discharge coefficient has a convex parabolic relation with S1 and a piecewise linearity relation with S2. The maximum discharge coefficient is always obtained at S2 = 0.8. There exists a difference between upstream and downstream slope coefficients in the influence range of free surface curvatures. Furthermore, a proposed discharge coefficient equation by nonlinear regression is a function of upstream and downstream slope coefficients.

Social conversational skills development in early implanted children.

Science.gov (United States)

Guerzoni, Letizia; Murri, Alessandra; Fabrizi, Enrico; Nicastri, Maria; Mancini, Patrizia; Cuda, Domenico

2016-09-01

Social conversational skills are a salient aspect of early pragmatic development in young children. These skills include two different abilities, assertiveness and responsiveness. This study investigated the development of these abilities in early implanted children and their relationships with lexical development and some language-sensitive variables. Prospective, observational, nonrandomized study. Participants included 28 children with congenital profound sensorineural hearing loss. The mean age at device activation was 13.3 months (standard deviation [SD] ±4.2). The Social-Conversational Skills Rating Scale was used to evaluate assertiveness and responsiveness. The MacArthur-Bates Communicative Development Inventory (Words and Sentences form) was used to analyze the lexical development. The device experience was 12 months for each child, and the mean age at testing was 25.9 months (SD ±4.6). Assertiveness and responsiveness scores were within the normal range of normal-hearing age-matched peers. Age at cochlear implant activation exerted a significant impact, with the highest scores associated to the youngest patients. The residual correlations between assertiveness and responsiveness with the lexical development were positive and strongly significant (r = 0.69 and 0.73, respectively). Preoperative hearing threshold demonstrated an associated significant coefficient on the assertiveness score. Age at diagnosis and maternal education level were not correlated with the social conversational skills. Early-implanted children developed social conversational skills that are similar to normal-hearing peers matched for age 1 year after device activation. Social conversational skills and lexical development were strongly correlated, but the present study design cannot specify the direction of this relationship. Children with better preoperative residual hearing exhibited better assertive ability. 4 Laryngoscope, 126:2098-2105, 2016. © 2015 The American Laryngological

On Some Pursuit and Evasion Differential Game Problems for an Infinite Number of First-Order Differential Equations

Directory of Open Access Journals (Sweden)

Abbas Badakaya Ja'afaru

2012-01-01

Full Text Available We study pursuit and evasion differential game problems described by infinite number of first-order differential equations with function coefficients in Hilbert space l2. Problems involving integral, geometric, and mix constraints to the control functions of the players are considered. In each case, we give sufficient conditions for completion of pursuit and for which evasion is possible. Consequently, strategy of the pursuer and control function of the evader are constructed in an explicit form for every problem considered.

Iodine-124 PET dosimetry in differentiated thyroid cancer: recovery coefficient in 2D and 3D modes for PET(/CT) systems.

Science.gov (United States)

Jentzen, Walter; Weise, Reiner; Kupferschläger, Jürgen; Freudenberg, Lutz; Brandau, Wolfgang; Bares, Ronald; Burchert, Wolfgang; Bockisch, Andreas

2008-03-01

This study evaluated the absolute quantification of iodine-124 ((124)I) activity concentration with respect to the use of this isotope for dosimetry before therapies with (131)I or (131)I-labeled radiotherapeuticals. The recovery coefficients of positron emission tomography(/computed tomography) PET(/CT) systems using (124)I were determined using phantoms and then validated under typical conditions observed in differentiated thyroid cancer (DTC) patients. Transversal spatial resolution and recovery measurements with (124)I and with fluorine-18 ((18)F) as the reference were performed using isotope-containing line sources embedded in water and six isotope-containing spheres 9.7 to 37.0 mm in diameter placed in water-containing body and cylinder phantoms. The cylinder phantom spheres were filled with (18)F only. Measurements in two-dimensional (2D) and three-dimensional (3D) modes were performed using both stand-alone PET (EXACT HR(+)) and combined PET/CT (BIOGRAPH EMOTION DUO) systems. Recovery comparison measurements were additionally performed on a GE ADVANCE PET system using the cylinder phantom. The recovery coefficients were directly determined using the activity concentration of circular regions of interest divided by the prepared activity concentration determined by the dose calibrator. The recovery correction method was validated using three consecutive scans of the body phantom under our (124)I PET(/CT) protocol for DTC patients. Compared with that of (18)F, transversal spatial resolution of (124)I was slightly, but statistically significantly degraded (7.4 mm vs. 8.3 mm, P or =12.6 mm in diameter. Recovery correction is mandatory for (124)I PET quantification, even for large structures. To ensure accurate dosimetry, thorough absolute recovery measurements must be individually established for the particular PET scanner and radionuclide to be used.

Linearized gravity in terms of differential forms

Science.gov (United States)

Baykal, Ahmet; Dereli, Tekin

2017-01-01

A technique to linearize gravitational field equations is developed in which the perturbation metric coefficients are treated as second rank, symmetric, 1-form fields belonging to the Minkowski background spacetime by using the exterior algebra of differential forms.

Approximate solution of integro-differential equation of fractional (arbitrary order

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Asma A. Elbeleze

2016-01-01

Full Text Available In the present paper, we study the integro-differential equations which are combination of differential and Fredholm–Volterra equations that have the fractional order with constant coefficients by the homotopy perturbation and the variational iteration. The fractional derivatives are described in Caputo sense. Some illustrative examples are presented.

On new classes of solutions of nonlinear partial differential equations in the form of convergent special series

Science.gov (United States)

Filimonov, M. Yu.

2017-12-01

The method of special series with recursively calculated coefficients is used to solve nonlinear partial differential equations. The recurrence of finding the coefficients of the series is achieved due to a special choice of functions, in powers of which the solution is expanded in a series. We obtain a sequence of linear partial differential equations to find the coefficients of the series constructed. In many cases, one can deal with a sequence of linear ordinary differential equations. We construct classes of solutions in the form of convergent series for a certain class of nonlinear evolution equations. A new class of solutions of generalized Boussinesque equation with an arbitrary function in the form of a convergent series is constructed.

Differential and difference equations a comparison of methods of solution

CERN Document Server

Maximon, Leonard C

2016-01-01

This book, intended for researchers and graduate students in physics, applied mathematics and engineering, presents a detailed comparison of the important methods of solution for linear differential and difference equations - variation of constants, reduction of order, Laplace transforms and generating functions - bringing out the similarities as well as the significant differences in the respective analyses. Equations of arbitrary order are studied, followed by a detailed analysis for equations of first and second order. Equations with polynomial coefficients are considered and explicit solutions for equations with linear coefficients are given, showing significant differences in the functional form of solutions of differential equations from those of difference equations. An alternative method of solution involving transformation of both the dependent and independent variables is given for both differential and difference equations. A comprehensive, detailed treatment of Green’s functions and the associat...

Wavelength conversion of a 40 Gb/s RZ-DPSK signal using four-wave mixing in a dispersion-flattened highly nonlinear photonic crystal fiber

DEFF Research Database (Denmark)

Andersen, Peter Andreas; Tokle, Torger; Geng, Yan

2005-01-01

Wavelength conversion of a 40-Gb/s return-to-zero differential phase-shift keying signal is demonstrated in a highly nonlinear photonic crystal fiber (HNL-PCF) for the first time. A conversion efficiency of -20 dB for a pump power of 23 dBm and a conversion bandwidth of 31 nm, essentially limited...

Discrimination of paediatric brain tumours using apparent diffusion coefficient histograms

International Nuclear Information System (INIS)

Bull, Jonathan G.; Clark, Christopher A.; Saunders, Dawn E.

2012-01-01

To determine if histograms of apparent diffusion coefficients (ADC) can be used to differentiate paediatric brain tumours. Imaging of histologically confirmed tumours with pre-operative ADC maps were reviewed (54 cases, 32 male, mean age 6.1 years; range 0.1-15.8 years) comprising 6 groups. Whole tumour ADC histograms were calculated; normalised for volume. Stepwise logistic regression analysis was used to differentiate tumour types using histogram metrics, initially for all groups and then for specific subsets. All 6 groups (5 dysembryoplastic neuroectodermal tumours, 22 primitive neuroectodermal tumours (PNET), 5 ependymomas, 7 choroid plexus papillomas, 4 atypical teratoid rhabdoid tumours (ATRT) and 9 juvenile pilocytic astrocytomas (JPA)) were compared. 74% (40/54) were correctly classified using logistic regression of ADC histogram parameters. In the analysis of posterior fossa tumours, 80% of ependymomas, 100% of astrocytomas and 94% of PNET-medulloblastoma were classified correctly. All PNETs were discriminated from ATRTs (22 PNET and 4 supratentorial ATRTs) (100%). ADC histograms are useful in differentiating paediatric brain tumours, in particular, the common posterior fossa tumours of childhood. PNETs were differentiated from supratentorial ATRTs, in all cases, which has important implications in terms of clinical management. (orig.)

Intracavity quasi-phase-matched self-frequency conversion in a periodically poled Nd:Mg:LiNbO3 crystal

International Nuclear Information System (INIS)

Laptev, G D; Novikov, Aleksei A

2001-01-01

The theory of intracavity quasi-phase-matched self-frequency conversion in an active nonlinear periodically poled structure is developed. The processes of quasi-phase-matched self-frequency doubling, self-halving and mixing using the pump wave in a periodically poled Nd:Mg:LiNbO 3 crystal are studied. The dependences of the efficiency of nonlinear optical conversion in these processes on the reflection coefficient of the output mirror and on linear losses in the medium are investigated. (nonlinear optical phenomena)

Monte Carlo calculations of calibrations of calibration coefficients of ATL monitors installed at NPP Temelin

International Nuclear Information System (INIS)

Solc, J.; Suran, J.; Novotna, M.; Pavlis, J.

2008-01-01

The contribution describes a technique of determination of calibration coefficients of a radioactivity monitor using Monte Carlo calculations. The monitor is installed at the NPP Temelin adjacent to lines with a radioactive medium. The output quantity is the activity concentration (in Bq/m3) that is converted from the number of counts per minute measured by the monitor. The value of this conversion constant, i.e. calibration coefficient, was calculated for gamma photons emitted by Co-60 and compared to the data stated by the manufacturer and supplier of these monitors, General Atomic Electronic Systems, Inc., USA. Results of the comparison show very good agreement between calculations and manufacturer data; the differences are lower than the quadratic sum of uncertainties. (authors)

Characterization of energy conversion of multiferroic PFN and PFN:Mn

Directory of Open Access Journals (Sweden)

Lucjan Kozielski

2013-12-01

Full Text Available Characterization of energy conversion of multiferroic materials is concerned with multifunctional properties of materials, a topic that is fascinating from the scientific point of view and important for the modern technology. The complex characterization of multiferroic structures suffers at present from lack of a systematic experimental approach and deficiency of multifunctional magnetoelectric properties testing capabilities. Compactness and high frequency energy conversion capacity are the main reasons of invention and improvement of sophisticated materials which are prepared for high-speed computer memories and broadband transducer devices. As a consequence, one can easily notice an intense search for new materials for generation, transformation and amplification of magnetic and electric energies. In this scenario, the combination of excellent piezoelectric and magnetic properties makes lead iron niobate Pb(Fe1/2Nb1/2O3 (PFN an attractive host material for application in integrated magnetoelectric energy conversion applications. PFN multiferroic materials are attractive for commercial electroceramics due to high value of dielectric permittivity and magnetoelectric coefficients as well as relatively easy synthesis process. However, synthesis of PFN ceramics is mostly connected with formation of the secondary unwanted pyrochlore phase associated with dramatic decrease of ferroelectric properties. The authors have successfully reduced this negative phenomenon by Mn doping and finally present high piezoelectric and magnetoelectric energy conversion efficiency in fabricated PMFN ceramics.

Fibonacci-like Differential Equations with a Polynomial Non-Homogeneous Part

NARCIS (Netherlands)

Asveld, P.R.J.

1989-01-01

We investigate non-homogeneous linear differential equations of the form $x''(t) + x'(t) - x(t) = p(t)$ where $p(t)$ is either a polynomial or a factorial polynomial in $t$. We express the solution of these differential equations in terms of the coefficients of $p(t)$, in the initial conditions, and

Comparison of Radiation Dose Rates with the Flux to Dose Conversion Factors Recommended in ICRP-74 and ICRP-116

International Nuclear Information System (INIS)

Jeong, Hae Sun; Kil, A Reum; Lee, Jo Eun; Jeong, Hyo Joon; Kim, Eun Han; Han, Moon Hee; Hwang, Won Tae

2016-01-01

The evaluation of radiation shielding has been performed for the design and maintenance of various facilities using radioactive sources such as nuclear fuel, accelerator, and radionuclide. The conversion of flux to dose mainly used in nuclear and radiation fields has been generally made with the dose coefficients presented in ICRP Publication 74 (ICRP- 74), which are produced based on ICRP Publication 60. On the other hand, ICRP Publication 116 (ICRP-116), which adopts the protection system of ICRP Publication 103, has recently been published and provides the dose conversion coefficients calculated with a variety of Monte Carlo codes. The coefficients have more than an update of those in ICRP-74, including new particle types and a greatly expanded energy range. In this study, a shielding evaluation of a specific container for neutron and gamma sources was performed with the MCNP6 code. The dose rates from neutron and gamma-ray sources were calculated using the MCNP6 codes, and these results were based on the flux to dose conversion factors recommended in ICRP-74 and ICRP-116. As a result, the dose rates evaluated with ICRP-74 were generally shown higher than those with ICRP-116. For neutrons, the difference is mainly occurred by the decrease of radiation weighting factors in a part of energy ranges in the ICRP-116 recommendations. For gamma-rays, the ICRP-74 recommendation applied with the kerma approximation leads to overestimated results than the other assessment

Classification of the coefficients of variation of parameters evaluated in Japanese quail experiments

Directory of Open Access Journals (Sweden)

DHV Leal

2014-06-01

Full Text Available The objective of this study was to design a classification range of the coefficients of variation (CV of traits used in experiments with eggtype Japanese quails (Coturnix coturnix japonica. The journal Revista Brasileira de Zootecnia was systematically reviewed, using the key word 'quail' during the period of January, 2000 to 2010. The CV of feed intake (g/bird/d, egg production (%/bird/d, egg weight (g, egg mass (g/bird/d, feed conversion ratio per dozen eggs (g/dozen, feed conversion ratio per egg mass (g/g, and egg specific gravity (g/mL were collected. For each parameter, CV were classified using the following median (MD and pseudo-sigma (PS ratio as follows: low (CV MD + 2PS. According to the results, it was concluded that each parameter has a specific classification range that should be taken into account when evaluating experimental precision.

Quantitative differentiation of breast lesions at 3T diffusion-weighted imaging (DWI) using the ratio of distributed diffusion coefficient (DDC).

Science.gov (United States)

Ertas, Gokhan; Onaygil, Can; Akin, Yasin; Kaya, Handan; Aribal, Erkin

2016-12-01

To investigate the accuracy of diffusion coefficients and diffusion coefficient ratios of breast lesions and of glandular breast tissue from mono- and stretched-exponential models for quantitative diagnosis in diffusion-weighted magnetic resonance imaging (MRI). We analyzed pathologically confirmed 170 lesions (85 benign and 85 malignant) imaged using a 3.0T MR scanner. Small regions of interest (ROIs) focusing on the highest signal intensity for lesions and also for glandular tissue of contralateral breast were obtained. Apparent diffusion coefficient (ADC) and distributed diffusion coefficient (DDC) were estimated by performing nonlinear fittings using mono- and stretched-exponential models, respectively. Coefficient ratios were calculated by dividing the lesion coefficient by the glandular tissue coefficient. A stretched exponential model provides significantly better fits then the monoexponential model (P DDC ratio (area under the curve [AUC] = 0.93) when compared with lesion DDC, ADC ratio, and lesion ADC (AUC = 0.91, 0.90, 0.90) but with no statistically significant difference (P > 0.05). At optimal thresholds, the DDC ratio achieves 93% sensitivity, 80% specificity, and 87% overall diagnostic accuracy, while ADC ratio leads to 89% sensitivity, 78% specificity, and 83% overall diagnostic accuracy. The stretched exponential model fits better with signal intensity measurements from both lesion and glandular tissue ROIs. Although the DDC ratio estimated by using the model shows a higher diagnostic accuracy than the ADC ratio, lesion DDC, and ADC, it is not statistically significant. J. Magn. Reson. Imaging 2016;44:1633-1641. © 2016 International Society for Magnetic Resonance in Medicine.

Chemical Conversion of Human Fibroblasts into Functional Schwann Cells

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Eva C. Thoma

2014-10-01

Full Text Available Direct transdifferentiation of somatic cells is a promising approach to obtain patient-specific cells for numerous applications. However, conversion across germ-layer borders often requires ectopic gene expression with unpredictable side effects. Here, we present a gene-free approach that allows efficient conversion of human fibroblasts via a transient progenitor stage into Schwann cells, the major glial cell type of peripheral nerves. Using a multikinase inhibitor, we transdifferentiated fibroblasts into transient neural precursors that were subsequently further differentiated into Schwann cells. The resulting induced Schwann cells (iSCs expressed numerous Schwann cell-specific proteins and displayed neurosupportive and myelination capacity in vitro. Thus, we established a strategy to obtain mature Schwann cells from human postnatal fibroblasts under chemically defined conditions without the introduction of ectopic genes.

Conversion of optical wave polarizations in 1D finite anisotropic photonic crystal

International Nuclear Information System (INIS)

Ouchani, N.; Nougaoui, N.; Daoudi, A.; Bria, D.

2006-07-01

We show that by using one dimensional anisotropic photonic structures, it is possible to realize optical wave polarization conversion by transmission or by reflection. Thus a single incident S(P) polarized plane wave can produce a single reflected P(S) polarized wave and a single transmitted P(S) polarized wave. This polarization conversion property can be fulfilled with a simple finite superlattice constituted by anisotropic dielectric materials. We discuss the appropriate choices of the material and geometrical properties to realize such structures. The transmission and reflection coefficients are discussed in relation with the dispersion curves of the finite structure embedded between two isotropic substrates. Both transmission and reflection coefficients are calculated in the framework of Green's function method. The amplitude and the polarization characteristics of reflected and transmitted waves are determined as function of frequency ω , and wave vector k parallel ( parallel to the interface) and the orientations of the principal axes of the layers constituting the SL. Moreover, this structure exhibits a coupling between S and P waves that does not exist in SL composed only of isotropic materials. Specific applications of these results are given for a superlattice consisting of alternating biaxial anisotropic layers NaNO 2 /SbSi sandwiched between two identical semi-infinite isotropic media. (author)

On the ideal and real energy conversion in a straight bladed vertical axis wind turbine. The actuator cylinder flow model compared with experiment

Energy Technology Data Exchange (ETDEWEB)

Aaagard Madsen, H.

1983-01-01

The ideal and the real energy conversion in a straight bladed vertical axis wind turbine (VAWT) with variable pitch has been studied on basis of the actuator cylinder flow model and experimental data from free wind tests on a 9 m/sup 2/ turbine. Particularly, the theoretical upper power limit of VAWT's has been focused upon in the light of the already existing theories for horizontal axis wind turbines (HAWT's). A remarkable result, differing from prior theories, has turned out through the computations with the actuator cylinder flow model and that is: The maximum ideal power coefficient for VAWT's seams neither to be bounded by the Lanchester-Betz power coefficient limit of 16/27 (actuator disc concept), nor by Glauert's ideal power coefficient curve (taking into account the tip speed ratio), both limits derived with particular reference to HAWT's. Concerning the agreement between analysis and the measurements of the power coefficient, the rotor drag coefficient and the flow velocity vector adjacent to the swept area, it was in general found to be good. However, there seems still to be need for future research on the influence of turbulence in the free wind and dynamic stall on the real energy conversion in VAWT's.

Internal conversion of the (13/2+→5/2-) isomeric transition in 199Hg

International Nuclear Information System (INIS)

Radha Krishna, K.; Chandrasekhar Rao, M.V.S.; Sree Krishna Murty, G.; Venkateswara Rao, N.; Bhuloka Reddy, S.; Satyanarayana, G.; Sastry, D.L.; Iyer, M.R.; Sahasrabhude, S.G.

1990-01-01

The total conversion coefficient of the M4 transition (374 KeV) in the decay of the 13/2 + isomeric state to 5/2 - state in 199 Hg measured using the relative gamma intensity method α T is determined to be 6.34 ± 0.29 in agreement with the theory due to Rosel et al. (author). 1 tab., 3 figs., 11 refs

Chiasmal coefficient of flash and pattern visual evoked potentials for detection of chiasmal misrouting in albinism

NARCIS (Netherlands)

Pott, JWR; Jansonius, NM; Kooijman, AC

The diagnosis of albinism can be confirmed by electrophysiological examination, when chiasmal misrouting can be demonstrated. The present study describes a quantitative analysis method for this purpose. A chiasmal coefficient (CC) was calculated by correlating the differential potential over left

Canonical coordinates for partial differential equations

Science.gov (United States)

Hunt, L. R.; Villarreal, Ramiro

1988-01-01

Necessary and sufficient conditions are found under which operators of the form Sigma (m, j=1) x (2) sub j + X sub O can be made constant coefficient. In addition, necessary and sufficient conditions are derived which classify those linear partial differential operators that can be moved to the Kolmogorov type.

Canonical coordinates for partial differential equations

Science.gov (United States)

Hunt, L. R.; Villarreal, Ramiro

1987-01-01

Necessary and sufficient conditions are found under which operators of the form Sigma(m, j=1) X(2)sub j + X sub 0 can be made constant coefficient. In addition, necessary and sufficient conditions are derived which classify those linear partial differential operators that can be moved to the Kolmogorov type.

Computation of Clebsch-Gordan and Gaunt coefficients using binomial coefficients

International Nuclear Information System (INIS)

Guseinov, I.I.; Oezmen, A.; Atav, Ue

1995-01-01

Using binomial coefficients the Clebsch-Gordan and Gaunt coefficients were calculated for extremely large quantum numbers. The main advantage of this approach is directly calculating these coefficients, instead of using recursion relations. Accuracy of the results is quite high for quantum numbers l 1 , and l 2 up to 100. Despite direct calculation, the CPU times are found comparable with those given in the related literature. 11 refs., 1 fig., 2 tabs

Dielectric metasurfaces solve differential and integro-differential equations.

Science.gov (United States)

Abdollahramezani, Sajjad; Chizari, Ata; Dorche, Ali Eshaghian; Jamali, Mohammad Vahid; Salehi, Jawad A

2017-04-01

Leveraging subwavelength resonant nanostructures, plasmonic metasurfaces have recently attracted much attention as a breakthrough concept for engineering optical waves both spatially and spectrally. However, inherent ohmic losses concomitant with low coupling efficiencies pose fundamental impediments over their practical applications. Not only can all-dielectric metasurfaces tackle such substantial drawbacks, but also their CMOS-compatible configurations support both Mie resonances that are invariant to the incident angle. Here, we report on a transmittive metasurface comprising arrayed silicon nanodisks embedded in a homogeneous dielectric medium to manipulate phase and amplitude of incident light locally and almost independently. By taking advantage of the interplay between the electric/magnetic resonances and employing general concepts of spatial Fourier transformation, a highly efficient metadevice is proposed to perform mathematical operations including solution of ordinary differential and integro-differential equations with constant coefficients. Our findings further substantiate dielectric metasurfaces as promising candidates for miniaturized, two-dimensional, and planar optical analog computing systems that are much thinner than their conventional lens-based counterparts.

Uranium conversion

International Nuclear Information System (INIS)

Oliver, Lena; Peterson, Jenny; Wilhelmsen, Katarina

2006-03-01

FOI, has performed a study on uranium conversion processes that are of importance in the production of different uranium compounds in the nuclear industry. The same conversion processes are of interest both when production of nuclear fuel and production of fissile material for nuclear weapons are considered. Countries that have nuclear weapons ambitions, with the intention to produce highly enriched uranium for weapons purposes, need some degree of uranium conversion capability depending on the uranium feed material available. This report describes the processes that are needed from uranium mining and milling to the different conversion processes for converting uranium ore concentrate to uranium hexafluoride. Uranium hexafluoride is the uranium compound used in most enrichment facilities. The processes needed to produce uranium dioxide for use in nuclear fuel and the processes needed to convert different uranium compounds to uranium metal - the form of uranium that is used in a nuclear weapon - are also presented. The production of uranium ore concentrate from uranium ore is included since uranium ore concentrate is the feed material required for a uranium conversion facility. Both the chemistry and principles or the different uranium conversion processes and the equipment needed in the processes are described. Since most of the equipment that is used in a uranium conversion facility is similar to that used in conventional chemical industry, it is difficult to determine if certain equipment is considered for uranium conversion or not. However, the chemical conversion processes where UF 6 and UF 4 are present require equipment that is made of corrosion resistant material

An Efficient Numerical Approach for Solving Nonlinear Coupled Hyperbolic Partial Differential Equations with Nonlocal Conditions

Directory of Open Access Journals (Sweden)

A. H. Bhrawy

2014-01-01

Full Text Available One of the most important advantages of collocation method is the possibility of dealing with nonlinear partial differential equations (PDEs as well as PDEs with variable coefficients. A numerical solution based on a Jacobi collocation method is extended to solve nonlinear coupled hyperbolic PDEs with variable coefficients subject to initial-boundary nonlocal conservation conditions. This approach, based on Jacobi polynomials and Gauss-Lobatto quadrature integration, reduces solving the nonlinear coupled hyperbolic PDEs with variable coefficients to a system of nonlinear ordinary differential equation which is far easier to solve. In fact, we deal with initial-boundary coupled hyperbolic PDEs with variable coefficients as well as initial-nonlocal conditions. Using triangular, soliton, and exponential-triangular solutions as exact solutions, the obtained results show that the proposed numerical algorithm is efficient and very accurate.

Computation of the Coupling Resonance Driving term f1001 and the coupling coefficient C from turn-by-turn single-BPM data.

CERN Document Server

Franchi, A; Vanbavinkhove, G; CERN. Geneva. BE Department

2010-01-01

In this note we show how to compute the Resonance Driving Term (RDT) f1001, the local resonance term chi 1010 and the coupling coefficient C from the spectrum of turn-by-turn single-BPM data. The harmonic analysis of real coordinate x(y) is model independent, conversely to the the analysis of the complex Courant-Snyder coordinate hx,- = x-ipx. From the computation of f1001 along the ring is closely related to the global coupling coefficient C, but it is affected by an intrinsic error, discussed in this note.

Sexy gene conversions: locating gene conversions on the X-chromosome.

Science.gov (United States)

Lawson, Mark J; Zhang, Liqing

2009-08-01

Gene conversion can have a profound impact on both the short- and long-term evolution of genes and genomes. Here, we examined the gene families that are located on the X-chromosomes of human (Homo sapiens), chimpanzee (Pan troglodytes), mouse (Mus musculus) and rat (Rattus norvegicus) for evidence of gene conversion. We identified seven gene families (WD repeat protein family, Ferritin Heavy Chain family, RAS-related Protein RAB-40 family, Diphosphoinositol polyphosphate phosphohydrolase family, Transcription Elongation Factor A family, LDOC1-related family, Zinc Finger Protein ZIC, and GLI family) that show evidence of gene conversion. Through phylogenetic analyses and synteny evidence, we show that gene conversion has played an important role in the evolution of these gene families and that gene conversion has occurred independently in both primates and rodents. Comparing the results with those of two gene conversion prediction programs (GENECONV and Partimatrix), we found that both GENECONV and Partimatrix have very high false negative rates (i.e. failed to predict gene conversions), which leads to many undetected gene conversions. The combination of phylogenetic analyses with physical synteny evidence exhibits high resolution in the detection of gene conversions.

Determination of the external mass transfer coefficient and influence of mixing intensity in moving bed biofilm reactors for wastewater treatment.

Science.gov (United States)

Nogueira, Bruno L; Pérez, Julio; van Loosdrecht, Mark C M; Secchi, Argimiro R; Dezotti, Márcia; Biscaia, Evaristo C

2015-09-01

In moving bed biofilm reactors (MBBR), the removal of pollutants from wastewater is due to the substrate consumption by bacteria attached on suspended carriers. As a biofilm process, the substrates are transported from the bulk phase to the biofilm passing through a mass transfer resistance layer. This study proposes a methodology to determine the external mass transfer coefficient and identify the influence of the mixing intensity on the conversion process in-situ in MBBR systems. The method allows the determination of the external mass transfer coefficient in the reactor, which is a major advantage when compared to the previous methods that require mimicking hydrodynamics of the reactor in a flow chamber or in a separate vessel. The proposed methodology was evaluated in an aerobic lab-scale system operating with COD removal and nitrification. The impact of the mixing intensity on the conversion rates for ammonium and COD was tested individually. When comparing the effect of mixing intensity on the removal rates of COD and ammonium, a higher apparent external mass transfer resistance was found for ammonium. For the used aeration intensities, the external mass transfer coefficient for ammonium oxidation was ranging from 0.68 to 13.50 m d(-1) and for COD removal 2.9 to 22.4 m d(-1). The lower coefficient range for ammonium oxidation is likely related to the location of nitrifiers deeper in the biofilm. The measurement of external mass transfer rates in MBBR will help in better design and evaluation of MBBR system-based technologies. Copyright © 2015 Elsevier Ltd. All rights reserved.

Comparison of Utility of Histogram Apparent Diffusion Coefficient and R2* for Differentiation of Low-Grade From High-Grade Clear Cell Renal Cell Carcinoma.

Science.gov (United States)

Zhang, Yu-Dong; Wu, Chen-Jiang; Wang, Qing; Zhang, Jing; Wang, Xiao-Ning; Liu, Xi-Sheng; Shi, Hai-Bin

2015-08-01

The purpose of this study was to compare histogram analysis of apparent diffusion coefficient (ADC) and R2* for differentiating low-grade from high-grade clear cell renal cell carcinoma (RCC). Forty-six patients with pathologically confirmed clear cell RCC underwent preoperative BOLD and DWI MRI of the kidneys. ADCs based on the entire tumor volume were calculated with b value combinations of 0 and 800 s/mm(2). ROI-based R2* was calculated with eight TE combinations of 6.7-22.8 milliseconds. Histogram analysis of tumor ADCs and R2* values was performed to obtain mean; median; width; and fifth, 10th, 90th, and 95th percentiles and histogram inhomogeneity, kurtosis, and skewness for all lesions. Thirty-three low-grade and 13 high-grade clear cell RCCs were found at pathologic examination. The TNM classification and tumor volume of clear cell RCC significantly correlated with histogram ADC and R2* (ρ = -0.317 to 0.506; p histogram ADC and R2* indexes, 10th percentile ADC had the highest accuracy (91.3%) in discriminating low- from high-grade clear cell RCC. R2* in discriminating hemorrhage was achieved with a threshold of 68.95 Hz. At this threshold, high-grade clear cell RCC had a significantly higher prevalence of intratumor hemorrhage (high-grade, 76.9%; low-grade, 45.4%; p Histogram analysis of ADC and R2* allows differentiation of low- from high-grade clear cell RCC with high accuracy.

Determination of the Rate Coefficients of the SO2 plus O plus M yields SO3 plus M Reaction

Science.gov (United States)

Hwang, S. M.; Cooke, J. A.; De Witt, K. J.; Rabinowitz, M. J.

2010-01-01

Rate coefficients of the title reaction R(sub 31) (SO2 +O+M yields SO3 +M) and R(sub 56) (SO2 + HO2 yields SO3 +OH), important in the conversion of S(IV) to S(VI),were obtained at T =970-1150 K and rho (sub ave) = 16.2 micro mol/cubic cm behind reflected shock waves by a perturbation method. Shock-heated H2/ O2/Ar mixtures were perturbed by adding small amounts of SO2 (1%, 2%, and 3%) and the OH temporal profiles were then measured using laser absorption spectroscopy. Reaction rate coefficients were elucidated by matching the characteristic reaction times acquired from the individual experimental absorption profiles via simultaneous optimization of k(sub 31) and k(sub 56) values in the reaction modeling (for satisfactory matches to the observed characteristic times, it was necessary to take into account R(sub 56)). In the experimental conditions of this study, R(sub 31) is in the low-pressure limit. The rate coefficient expressions fitted using the combined data of this study and the previous experimental results are k(sub 31,0)/[Ar] = 2.9 10(exp 35) T(exp ?6.0) exp(?4780 K/T ) + 6.1 10(exp 24) T(exp ?3.0) exp(?1980 K/T ) cm(sup 6) mol(exp ?2)/ s at T = 300-2500 K; k(sub 56) = 1.36 10(exp 11) exp(?3420 K/T ) cm(exp 3)/mol/s at T = 970-1150 K. Computer simulations of typical aircraft engine environments, using the reaction mechanism with the above k(sub 31,0) and k(sub 56) expressions, gave the maximum S(IV) to S(VI) conversion yield of ca. 3.5% and 2.5% for the constant density and constant pressure flow condition, respectively. Moreover, maximum conversions occur at rather higher temperatures (?1200 K) than that where the maximum k(sub 31,0) value is located (approximately 800 K). This is because the conversion yield is dependent upon not only the k(sup 31,0) and k(sup 56) values (production flux) but also the availability of H, O, and HO2 in the system (consumption flux).

The Role of Conversation Policy in Carrying Out Agent Conversations

International Nuclear Information System (INIS)

Link, Hamilton E.; Phillips, Laurence R.

1999-01-01

Structured conversation diagrams, or conversation specifications, allow agents to have predictable interactions and achieve predefined information-based goals, but they lack the flexibility needed to function robustly in an unpredictable environment. We propose a mechanism that combines a typical conversation structure with a separately established policy to generate an actual conversation. The word ''policy'' connotes a high-level direction external to a specific planned interaction with the environment. Policies, which describe acceptable procedures and influence decisions, can be applied to broad sets of activity. Based on their observation of issues related to a policy, agents may dynamically adjust their communication patterns. The policy object describes limitations, constraints, and requirements that may affect the conversation in certain circumstances. Using this new mechanism of interaction simplifies the description of individual conversations and allows domain-specific issues to be brought to bear more easily during agent communication. By following the behavior of the conversation specification when possible and deferring to the policy to derive behavior in exceptional circumstances, an agent is able to function predictably under normal situations and still act rationally in abnormal situations. Different conversation policies applied to a given conversation specification can change the nature of the interaction without changing the specification

Thermoelectric Energy Conversion: Materials, Devices, and Systems

International Nuclear Information System (INIS)

Chen, Gang

2015-01-01

This paper will present a discussion of challenges, progresses, and opportunities in thermoelectric energy conversion technology. We will start with an introduction to thermoelectric technology, followed by discussing advances in thermoelectric materials, devices, and systems. Thermoelectric energy conversion exploits the Seebeck effect to convert thermal energy into electricity, or the Peltier effect for heat pumping applications. Thermoelectric devices are scalable, capable of generating power from nano Watts to mega Watts. One key issue is to improve materials thermoelectric figure- of-merit that is linearly proportional to the Seebeck coefficient, the square of the electrical conductivity, and inversely proportional to the thermal conductivity. Improving the figure-of-merit requires good understanding of electron and phonon transport as their properties are often contradictory in trends. Over the past decade, excellent progresses have been made in the understanding of electron and phonon transport in thermoelectric materials, and in improving existing and identify new materials, especially by exploring nanoscale size effects. Taking materials to real world applications, however, faces more challenges in terms of materials stability, device fabrication, thermal management and system design. Progresses and lessons learnt from our effort in fabricating thermoelectric devices will be discussed. We have demonstrated device thermal-to-electrical energy conversion efficiency ∼10% and solar-thermoelectric generator efficiency at 4.6% without optical concentration of sunlight (Figure 1) and ∼8-9% efficiency with optical concentration. Great opportunities exist in advancing materials as well as in using existing materials for energy efficiency improvements and renewable energy utilization, as well as mobile applications. (paper)

Role of apparent diffusion coefficient values and diffusion weighted magnetic resonance imaging in differentiation between benign and malignant thyroid nodules

International Nuclear Information System (INIS)

Incedayi, M.; Sivrioglu, A.; Mutlu, H.; Sonmez, G.; Velioglu, M.; Sildiroglu, O.; Basekim, C.; Kizilkaya, E.

2012-01-01

Full text: Objective: The purpose of the study was to differentiate between benign and malignant thyroid nodules using nodule-spinal cord signal intensity and nodule apparent diffusion coefficient (ADC) ratios on diffusion weighted magnetic resonance imaging. Materials and methods: Forty-four patients (27 females, 17 males; mean age 49) with nodules who underwent diffusion weighted magnetic resonance imaging (DW-MRI) were included in this study. The images were acquired with 0, 50, 400 and 1000 s/mm 2 b values. ADC maps were calculated afterwards. Fine needle aspiration biopsies (FNAB) were performed at the same day with DW-MRI acquisition. The diagnosis in patients where malignity was detected after FNAB was confirmed by histopathologic analysis of the operation material. The signal intensities of the spinal cord and the nodule were measured additionally, over b-1000 diffusion weighted images. Nodule /cord signal intensity (SI) ratios were obtained and the digital values were calculated by dividing to ADC values estimated for each nodule. Statistical analysis was performed. Results: The (nodule SI-cord SI)/nodule ADC ratio is calculated in the DW images and a statistically significant relationship was found between this ratio and the histopathology of the nodules (p<0.001). The ratio was determined as 0.27 in benign, and 0.86 in malignant lesions. The result of ROC analysis was statistically significant, and the area under Receiver Operating Characteristic (ROC) curve (100%) was considerably high. The threshold value was calculated as 0.56 according to the ROC analysis. According to this threshold value, the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy rates for (nodule SI/cord SI)/ADC ratios in differentiating benign from malignant thyroid nodules are calculated as 100%, 97%, 83%, 100%, and 98%, respectively. Conclusion: We have found that (nodule/cord SI)/ nodule ADC ratio has the highest values for

Bipartite Fuzzy Stochastic Differential Equations with Global Lipschitz Condition

Directory of Open Access Journals (Sweden)

Marek T. Malinowski

2016-01-01

Full Text Available We introduce and analyze a new type of fuzzy stochastic differential equations. We consider equations with drift and diffusion terms occurring at both sides of equations. Therefore we call them the bipartite fuzzy stochastic differential equations. Under the Lipschitz and boundedness conditions imposed on drifts and diffusions coefficients we prove existence of a unique solution. Then, insensitivity of the solution under small changes of data of equation is examined. Finally, we mention that all results can be repeated for solutions to bipartite set-valued stochastic differential equations.

Better resolved low frequency dispersions by the apt use of Kramers-Kronig relations, differential operators and all-in-1 modelling

Directory of Open Access Journals (Sweden)

Jan van Turnhout

2016-05-01

Full Text Available The dielectric spectra of colloidal systems often contain a typical low frequency dispersion, which usually remains unnoticed, because of the presence of strong conduction losses. The KK relations offer a means for converting  into  data. This allows us to calculate conduction free  spectra in which the l.f. dispersion will show up undisturbed. This interconversion can be done on line with a moving frame of logarithmically spaced  data. The coefficients of the conversion frames were obtained by kernel matching and by using symbolic differential operators. Logarithmic derivatives and differences of  and  provide another option for conduction free data analysis. These difference-based functions actually derived from approximations to the distribution function, have the additional advantage of improving the resolution power of dielectric studies. A high resolution is important because of the rich relaxation structure of colloidal suspensions. The development of all-in-1 modelling facilitates the conduction free and high resolution data analysis. This mathematical tool allows the apart-together fitting of multiple data and multiple model functions. It proved also useful to go around the KK conversion altogether. This was achieved by the combined approximating  and  data with a complex rational fractional power function. The all-in-1 minimization turned out to be also highly useful for the dielectric modelling of a suspension with the complex dipolar coefficient. It guarantees a secure correction for the electrode polarization, so that the modelling with the help of the differences  and  can zoom in on the genuine colloidal relaxations.

Cyclotron absorption and emission in mode conversion layers emdash a new paradigm

International Nuclear Information System (INIS)

Swanson, D.G.

1995-01-01

When the analysis of absorption with mode conversion effects included began to mature in recent years, the study of the corresponding effects on emission began and has led to some surprising results. The classical expressions for cyclotron or synchrotron emission from a harmonic resonance were originally derived from models that did not include mode conversion or its attendant reflection, and classical expressions for the optical depth and opacity were obtained. When mode conversion was included, the principal surprise was that the transmission coefficient, which was understood as being due to absorption, is totally independent of absorption and due exclusively to tunneling. The other surprise from the mode conversion analysis is that the observed emission arises from two distinct sources, one direct and one from an indirect Bernstein wave source which is partially converted in the cyclotron layer to outgoing electromagnetic waves, with the net result that mode conversion cancels out for the electron case, but not for ions. The only corrections to electron cyclotron emission are then due to reflection effects, and these have been shown to be small for many laboratory plasmas, leading to the validation of the classical formula for these cases, but via an entirely new paradigm in its interpretation. This review includes a summary of the absorption process for both electron and ion cyclotron harmonics, and reviews carefully the emission physics, including both potential error estimates and a discussion of the emission source distribution in space

Calculation of photon attenuation coefficients of elements and compounds from approximate semi-analytical formulae

Energy Technology Data Exchange (ETDEWEB)

Roteta, M; Baro, J; Fernandez-Varea, J M; Salvat, F

1994-07-01

The FORTRAN 77 code PHOTAC to compute photon attenuation coefficients of elements and compounds is described. The code is based on the semi analytical approximate atomic cross sections proposed by Baro et al. (1994). Photoelectric cross sections for coherent and incoherent scattering and for pair production are obtained as integrals of the corresponding differential cross sections. These integrals are evaluated, to a pre-selected accuracy, by using a 20-point Gauss adaptive integration algorithm. Calculated attenuation coefficients agree with recently compiled databases to within - 1%, in the energy range from 1 keV to 1 GeV. The complete source listing of the program PHOTAC is included. (Author) 14 refs.

Calculation of photon attenuation coefficients of elements and compounds from approximate semi-analytical formulae

International Nuclear Information System (INIS)

Roteta, M.; Baro, J.; Fernandez-Varea, J. M.; Salvat, F.

1994-01-01

The FORTRAN 77 code PHOTAC to compute photon attenuation coefficients of elements and compounds is described. The code is based on the semi analytical approximate atomic cross sections proposed by Baro et al. (1994). Photoelectric cross sections for coherent and incoherent scattering and for pair production are obtained as integrals of the corresponding differential cross sections. These integrals are evaluated, to a pre-selected accuracy, by using a 20-point Gauss adaptive integration algorithm. Calculated attenuation coefficients agree with recently compiled databases to within - 1%, in the energy range from 1 keV to 1 GeV. The complete source listing of the program PHOTAC is included. (Author) 14 refs

White top-emitting OLEDs using organic colour-conversion layers for improved colour-stability

Energy Technology Data Exchange (ETDEWEB)

Schwab, Tobias; Hofmann, Simone; Thomschke, Michael; Luessem, Bjoern; Leo, Karl [Institut fuer Angewandte Photophysik, Technische Universitaet Dresden (Germany)

2011-07-01

In contrast to white organic light-emitting diodes (OLEDs) using several vertical stacked emitters, the principle of down-conversion gives the chance to achieve white light with a simplified layer structure and enhanced colour stability by preventing a colour shift over lifetime due to differential aging of dyes. We investigate an approach where the conversion material is integrated into a top-emitting OLED structure in a way, that only electrons can pass this layer. This assures optical excitation and avoids unwanted electrical recombination inside the conversion layer. The emission spectra, CIE-coordinates, efficiencies, and IV-characteristics depending on the conversion layer thickness have been determined and were compared to the non-emitting host-material with similar optical properties. Lifetime measurements show that these OLEDs have almost no colour change over an investigated period up to 2200 hours. It is shown that the external quantum efficiency of the OLED does not necessarily decrease with an increased conversion layer thickness, even if the photoluminescence quantum yield of these materials is below unity. This indicates that the efficiency is improved by out-coupling of isotropic re-emitted wave-guided modes.

Interregional income differentials and migration: their interrelationships.

Science.gov (United States)

Tabuchi, T

1988-02-01

"The major objective of this paper is to demonstrate that interregional income differential is exogenous to interregional net migration, but not conversely. Utilizing Japanese prefectural-based data for 1954-82, we conduct the following three kinds of analyses to confirm this statement. Firstly, a simple comparison of the crests of interregional time-series plots was made to see which occurred first. Secondly, Sims', 1972, test of causality was done to investigate causation between urban/rural income differential and net migration. Finally, per capita income and population share were examined by two-dimensional phase diagram for nine regions." (SUMMARY IN FRE AND GER) excerpt

Simultaneous estimation of diet composition and calibration coefficients with fatty acid signature data

Science.gov (United States)

Bromaghin, Jeffrey F.; Budge, Suzanne M.; Thiemann, Gregory W.; Rode, Karyn D.

2017-01-01

Knowledge of animal diets provides essential insights into their life history and ecology, although diet estimation is challenging and remains an active area of research. Quantitative fatty acid signature analysis (QFASA) has become a popular method of estimating diet composition, especially for marine species. A primary assumption of QFASA is that constants called calibration coefficients, which account for the differential metabolism of individual fatty acids, are known. In practice, however, calibration coefficients are not known, but rather have been estimated in feeding trials with captive animals of a limited number of model species. The impossibility of verifying the accuracy of feeding trial derived calibration coefficients to estimate the diets of wild animals is a foundational problem with QFASA that has generated considerable criticism. We present a new model that allows simultaneous estimation of diet composition and calibration coefficients based only on fatty acid signature samples from wild predators and potential prey. Our model performed almost flawlessly in four tests with constructed examples, estimating both diet proportions and calibration coefficients with essentially no error. We also applied the model to data from Chukchi Sea polar bears, obtaining diet estimates that were more diverse than estimates conditioned on feeding trial calibration coefficients. Our model avoids bias in diet estimates caused by conditioning on inaccurate calibration coefficients, invalidates the primary criticism of QFASA, eliminates the need to conduct feeding trials solely for diet estimation, and consequently expands the utility of fatty acid data to investigate aspects of ecology linked to animal diets.

Estimating Seebeck Coefficient of a p-Type High Temperature Thermoelectric Material Using Bee Algorithm Multi-layer Perception

Science.gov (United States)

Uysal, Fatih; Kilinc, Enes; Kurt, Huseyin; Celik, Erdal; Dugenci, Muharrem; Sagiroglu, Selami

2017-08-01

Thermoelectric generators (TEGs) convert heat into electrical energy. These energy-conversion systems do not involve any moving parts and are made of thermoelectric (TE) elements connected electrically in a series and thermally in parallel; however, they are currently not suitable for use in regular operations due to their low efficiency levels. In order to produce high-efficiency TEGs, there is a need for highly heat-resistant thermoelectric materials (TEMs) with an improved figure of merit ( ZT). Production and test methods used for TEMs today are highly expensive. This study attempts to estimate the Seebeck coefficient of TEMs by using the values of existing materials in the literature. The estimation is made within an artificial neural network (ANN) based on the amount of doping and production methods. Results of the estimations show that the Seebeck coefficient can approximate the real values with an average accuracy of 94.4%. In addition, ANN has detected that any change in production methods is followed by a change in the Seebeck coefficient.

The differential equation of an arbitrary reflecting surface

Science.gov (United States)

Melka, Richard F.; Berrettini, Vincent D.; Yousif, Hashim A.

2018-05-01

A differential equation describing the reflection of a light ray incident upon an arbitrary reflecting surface is obtained using the law of reflection. The derived equation is written in terms of a parameter and the value of this parameter determines the nature of the reflecting surface. Under various parametric constraints, the solution of the differential equation leads to the various conic surfaces but is not generally solvable. In addition, the dynamics of the light reflections from the conic surfaces are executed in the Mathematica software. Our derivation is the converse of the traditional approach and our analysis assumes a relation between the object distance and the image distance. This leads to the differential equation of the reflecting surface.

Coefficient estimates of negative powers and inverse coefficients for ...

Indian Academy of Sciences (India)

and the inequality is sharp for the inverse of the Koebe function k(z) = z/(1 − z)2. An alternative approach to the inverse coefficient problem for functions in the class S has been investigated by Schaeffer and Spencer [27] and FitzGerald [6]. Although, the inverse coefficient problem for the class S has been completely solved ...

Sparse dynamics for partial differential equations.

Science.gov (United States)

Schaeffer, Hayden; Caflisch, Russel; Hauck, Cory D; Osher, Stanley

2013-04-23

We investigate the approximate dynamics of several differential equations when the solutions are restricted to a sparse subset of a given basis. The restriction is enforced at every time step by simply applying soft thresholding to the coefficients of the basis approximation. By reducing or compressing the information needed to represent the solution at every step, only the essential dynamics are represented. In many cases, there are natural bases derived from the differential equations, which promote sparsity. We find that our method successfully reduces the dynamics of convection equations, diffusion equations, weak shocks, and vorticity equations with high-frequency source terms.

Differential and Difference Boundary Value Problem for Loaded Third-Order Pseudo-Parabolic Differential Equations and Difference Methods for Their Numerical Solution

Science.gov (United States)

Beshtokov, M. Kh.

2017-12-01

Boundary value problems for loaded third-order pseudo-parabolic equations with variable coefficients are considered. A priori estimates for the solutions of the problems in the differential and difference formulations are obtained. These a priori estimates imply the uniqueness and stability of the solution with respect to the initial data and the right-hand side on a layer, as well as the convergence of the solution of each difference problem to the solution of the corresponding differential problem.

Hello, Who is Calling?: Can Words Reveal the Social Nature of Conversations?

Science.gov (United States)

Stark, Anthony; Shafran, Izhak; Kaye, Jeffrey

2012-01-01

This study aims to infer the social nature of conversations from their content automatically. To place this work in context, our motivation stems from the need to understand how social disengagement affects cognitive decline or depression among older adults. For this purpose, we collected a comprehensive and naturalistic corpus comprising of all the incoming and outgoing telephone calls from 10 subjects over the duration of a year. As a first step, we learned a binary classifier to filter out business related conversation, achieving an accuracy of about 85%. This classification task provides a convenient tool to probe the nature of telephone conversations. We evaluated the utility of openings and closing in differentiating personal calls, and find that empirical results on a large corpus do not support the hypotheses by Schegloff and Sacks that personal conversations are marked by unique closing structures. For classifying different types of social relationships such as family vs other, we investigated features related to language use (entropy), hand-crafted dictionary (LIWC) and topics learned using unsupervised latent Dirichlet models (LDA). Our results show that the posteriors over topics from LDA provide consistently higher accuracy (60-81%) compared to LIWC or language use features in distinguishing different types of conversations.

Temperature dependence of He(2 3PJ) reactions: Collision-induced mixing and conversion to He2( 3Πg) molecules

International Nuclear Information System (INIS)

Zhao, X.; Soletsky, P.A.; Bryan, W.H.; Dunning, F.B.; Walters, G.K.

1993-01-01

The rate coefficients for mixing between He(2 3 P J, MJ) levels during collisions with ground-state helium atoms and for conversion of He(2 3 P J ) atoms to He 2 (b 3 Π g ) molecules via three-body reactions in helium gas have been investigated over the temperature range 1.6--300 K. The measured rate coefficients for collisionally induced P-state mixing decrease slowly with decreasing temperature, from (1.8±0.5)x10 -9 cm 3 s -1 at 300 K to (4.5±0.5)x10 -10 cm 3 s -1 at 4.2 K. The rate coefficients for the production of He 2 (b 3 Π g ) molecules via three-body reactions are observed to increase with decreasing temperature and are described by the relation k P congruent(2.5+267T -1 )x10 -32 cm 6 s -1 . This behavior, which is very different from that noted in earlier studies of the conversion of He(2 3 S 1 ) atoms to He 2 (a 3 Σ u + ) molecules through three-body reactions, suggests that the reaction is not thermally activated

Application of Legendre spectral-collocation method to delay differential and stochastic delay differential equation

Science.gov (United States)

Khan, Sami Ullah; Ali, Ishtiaq

2018-03-01

Explicit solutions to delay differential equation (DDE) and stochastic delay differential equation (SDDE) can rarely be obtained, therefore numerical methods are adopted to solve these DDE and SDDE. While on the other hand due to unstable nature of both DDE and SDDE numerical solutions are also not straight forward and required more attention. In this study, we derive an efficient numerical scheme for DDE and SDDE based on Legendre spectral-collocation method, which proved to be numerical methods that can significantly speed up the computation. The method transforms the given differential equation into a matrix equation by means of Legendre collocation points which correspond to a system of algebraic equations with unknown Legendre coefficients. The efficiency of the proposed method is confirmed by some numerical examples. We found that our numerical technique has a very good agreement with other methods with less computational effort.

Maximum Efficiency of Thermoelectric Heat Conversion in High-Temperature Power Devices

Directory of Open Access Journals (Sweden)

V. I. Khvesyuk

2016-01-01

Full Text Available Modern trends in development of aircraft engineering go with development of vehicles of the fifth generation. The features of aircrafts of the fifth generation are motivation to use new high-performance systems of onboard power supply. The operating temperature of the outer walls of engines is of 800–1000 K. This corresponds to radiation heat flux of 10 kW/m2 . The thermal energy including radiation of the engine wall may potentially be converted into electricity. The main objective of this paper is to analyze if it is possible to use a high efficiency thermoelectric conversion of heat into electricity. The paper considers issues such as working processes, choice of materials, and optimization of thermoelectric conversion. It presents the analysis results of operating conditions of thermoelectric generator (TEG used in advanced hightemperature power devices. A high-temperature heat source is a favorable factor for the thermoelectric conversion of heat. It is shown that for existing thermoelectric materials a theoretical conversion efficiency can reach the level of 15–20% at temperatures up to 1500 K and available values of Ioffe parameter being ZT = 2–3 (Z is figure of merit, T is temperature. To ensure temperature regime and high efficiency thermoelectric conversion simultaneously it is necessary to have a certain match between TEG power, temperature of hot and cold surfaces, and heat transfer coefficient of the cooling system. The paper discusses a concept of radiation absorber on the TEG hot surface. The analysis has demonstrated a number of potentialities for highly efficient conversion through using the TEG in high-temperature power devices. This work has been implemented under support of the Ministry of Education and Science of the Russian Federation; project No. 1145 (the programme “Organization of Research Engineering Activities”.

Temperature coefficients for GaInP/GaAs/GaInNAsSb solar cells

Energy Technology Data Exchange (ETDEWEB)

Aho, Arto; Isoaho, Riku; Tukiainen, Antti; Polojärvi, Ville; Aho, Timo; Raappana, Marianna; Guina, Mircea [Optoelectronics Research Centre, Tampere University of Technology, P.O. Box 692, FIN-33101 Tampere (Finland)

2015-09-28

We report the temperature coefficients for MBE-grown GaInP/GaAs/GaInNAsSb multijunction solar cells and the corresponding single junction sub-cells. Temperature-dependent current-voltage measurements were carried out using a solar simulator equipped with a 1000 W Xenon lamp and a three-band AM1.5D simulator. The triple-junction cell exhibited an efficiency of 31% at AM1.5G illumination and an efficiency of 37–39% at 70x real sun concentration. The external quantum efficiency was also measured at different temperatures. The temperature coefficients up to 80°C, for the open circuit voltage, the short circuit current density, and the conversion efficiency were determined to be −7.5 mV/°C, 0.040 mA/cm{sup 2}/°C, and −0.09%/°C, respectively.

Improvement of skeleton conversion in ICRP reference phantom conversion project

Energy Technology Data Exchange (ETDEWEB)

Wang, Zhao Jun; Yeom, Yeon Soo; Thang, Nguyen Tat; Kim, Han Sung; Han, Min Cheol; Kim, Chan Hyeong [Dept. of Nuclear Engineering, Hanyang University, Seoul (Korea, Republic of); Kim, Seong Hoon [Dept. of Radiation Oncology, College of Medicine, Hanyang University, Seoul (Korea, Republic of)

2014-11-15

In the previous skeleton conversion, most bones were directly converted from the ICRP voxel phantoms by using the 3D rendering method whereas several complex-shape bones (cranium, ribs, spines, feet, and hands) were not able to be directly converted. We alternatively employed the corresponding well-defined polygonal models and attempted to adjust them to match the voxel models. However, this approach was unsatisfactory. The shapes of the alternative models were significantly different from those of the voxel models, making it virtually impossible to exactly match the voxel models as shown in Fig. 3 (left). In order to overcome the difficulty in the complex bone conversion, the present study developed a new conversion method and converted these complex bones voxel models of the ICRP male phantom to polygonal models. The present study developed the new conversion method and successfully improved polygonal models for cranium, ribs, and spines for the ICRP male phantom. The new conversion method will be also applied to the complex bone conversion for the ICRP female phantom as well as other complex organ conversion in the future.

Improvement of skeleton conversion in ICRP reference phantom conversion project

International Nuclear Information System (INIS)

Wang, Zhao Jun; Yeom, Yeon Soo; Thang, Nguyen Tat; Kim, Han Sung; Han, Min Cheol; Kim, Chan Hyeong; Kim, Seong Hoon

2014-01-01

In the previous skeleton conversion, most bones were directly converted from the ICRP voxel phantoms by using the 3D rendering method whereas several complex-shape bones (cranium, ribs, spines, feet, and hands) were not able to be directly converted. We alternatively employed the corresponding well-defined polygonal models and attempted to adjust them to match the voxel models. However, this approach was unsatisfactory. The shapes of the alternative models were significantly different from those of the voxel models, making it virtually impossible to exactly match the voxel models as shown in Fig. 3 (left). In order to overcome the difficulty in the complex bone conversion, the present study developed a new conversion method and converted these complex bones voxel models of the ICRP male phantom to polygonal models. The present study developed the new conversion method and successfully improved polygonal models for cranium, ribs, and spines for the ICRP male phantom. The new conversion method will be also applied to the complex bone conversion for the ICRP female phantom as well as other complex organ conversion in the future

Advanced high conversion PWR: preliminary analysis

International Nuclear Information System (INIS)

Golfier, H.; Bellanger, V.; Bergeron, A.; Dolci, F.; Gastaldi, B.; Koberl, O.; Mignot, G.; Thevenot, C.

2007-01-01

In this paper, physical aspects of a HCPWR (High Conversion Light Water Reactor), which is an innovative PWR fuelled with mixed oxide and having a higher conversion ratio due to a lower moderation ratio. Moderation ratios lower than unity are considered which has led to low moderation PWR fuel assembly designs. The objectives of this parametric study are to define a feasibility area with regard to the following neutronic aspects: moderation ratio, Pu loading, reactor spectrum, irradiation time, and neutronic coefficients. Important thermohydraulic parameters are the pressure drop, the critical heat flux, the maximum temperature in the fuel rod and the pumping power. The thermohydraulic analysis shows that a range of moderation ratios from 0.8 to 1.2 is technically possible. A compromise between improved fuel utilization and research and development effort has been found for the moderation ration of about 1. The parametric study shows that there are 2 ranges of interest for the moderation ratio: -) moderation ratio between 0.8 and 1.2 with reduced fissile heights (> 3 m), hexagonal arrangement fuel assembly and square arrangement fuel assembly are possible; and -) moderation between 0.6 and 0.7 with a modification of the reactor operating conditions (reduction of the primary flow and of the thermal power), the fuel rods could be arranged inside a hexagonal fuel rod assembly. (A.C.)

Fuchs indices and the first integrals of nonlinear differential equations

International Nuclear Information System (INIS)

Kudryashov, Nikolai A.

2005-01-01

New method of finding the first integrals of nonlinear differential equations in polynomial form is presented. Basic idea of our approach is to use the scaling of solution of nonlinear differential equation and to find the dimensions of arbitrary constants in the Laurent expansion of the general solution. These dimensions allows us to obtain the scalings of members for the first integrals of nonlinear differential equations. Taking the polynomials with unknown coefficients into account we present the algorithm of finding the first integrals of nonlinear differential equations in the polynomial form. Our method is applied to look for the first integrals of eight nonlinear ordinary differential equations of the fourth order. The general solution of one of the fourth order ordinary differential equations is given

Assessment of dose conversion factors in a generic biosphere of a Korea HLW repository

International Nuclear Information System (INIS)

Hwang, Y. S.; Park, J. B.; Kang, C. H.

2002-01-01

Radioactive species released from a waste repository migrate through engineered and natural barriers and eventually reach the biosphere. Once entered the biosphere, contaminants transport various exposure pathways and finally reach a human. In this study the full RES matrix explaining the key compartments in the biosphere and their interactions is introduced considering the characteristics of the Korean biosphere. Then the three exposure groups are identified based on the compartments of interest. The full exposure pathways and corresponding mathematical expression for mass transfer coefficients and etc are developed and applied to assess the dose conversion factors of nuclides for a specific exposure group. Dose conversion factors assessed in this study will be used for total system performance assessment of a potential Korean HLW repository

Linear matrix differential equations of higher-order and applications

Directory of Open Access Journals (Sweden)

Mustapha Rachidi

2008-07-01

Full Text Available In this article, we study linear differential equations of higher-order whose coefficients are square matrices. The combinatorial method for computing the matrix powers and exponential is adopted. New formulas representing auxiliary results are obtained. This allows us to prove properties of a large class of linear matrix differential equations of higher-order, in particular results of Apostol and Kolodner are recovered. Also illustrative examples and applications are presented.

Backward Stochastic Riccati Equations and Infinite Horizon L-Q Optimal Control with Infinite Dimensional State Space and Random Coefficients

International Nuclear Information System (INIS)

Guatteri, Giuseppina; Tessitore, Gianmario

2008-01-01

We study the Riccati equation arising in a class of quadratic optimal control problems with infinite dimensional stochastic differential state equation and infinite horizon cost functional. We allow the coefficients, both in the state equation and in the cost, to be random.In such a context backward stochastic Riccati equations are backward stochastic differential equations in the whole positive real axis that involve quadratic non-linearities and take values in a non-Hilbertian space. We prove existence of a minimal non-negative solution and, under additional assumptions, its uniqueness. We show that such a solution allows to perform the synthesis of the optimal control and investigate its attractivity properties. Finally the case where the coefficients are stationary is addressed and an example concerning a controlled wave equation in random media is proposed

Coefficient Alpha: A Reliability Coefficient for the 21st Century?

Science.gov (United States)

Yang, Yanyun; Green, Samuel B.

2011-01-01

Coefficient alpha is almost universally applied to assess reliability of scales in psychology. We argue that researchers should consider alternatives to coefficient alpha. Our preference is for structural equation modeling (SEM) estimates of reliability because they are informative and allow for an empirical evaluation of the assumptions…

High-accuracy resolver-to-digital conversion via phase locked loop based on PID controller

Science.gov (United States)

Li, Yaoling; Wu, Zhong

2018-03-01

The problem of resolver-to-digital conversion (RDC) is transformed into the problem of angle tracking control, and a phase locked loop (PLL) method based on PID controller is proposed in this paper. This controller comprises a typical PI controller plus an incomplete differential which can avoid the amplification of higher-frequency noise components by filtering the phase detection error with a low-pass filter. Compared with conventional ones, the proposed PLL method makes the converter a system of type III and thus the conversion accuracy can be improved. Experimental results demonstrate the effectiveness of the proposed method.

Response of selected binomial coefficients to varying degrees of matrix sparseness and to matrices with known data interrelationships

Science.gov (United States)

Archer, A.W.; Maples, C.G.

1989-01-01

Numerous departures from ideal relationships are revealed by Monte Carlo simulations of widely accepted binomial coefficients. For example, simulations incorporating varying levels of matrix sparseness (presence of zeros indicating lack of data) and computation of expected values reveal that not only are all common coefficients influenced by zero data, but also that some coefficients do not discriminate between sparse or dense matrices (few zero data). Such coefficients computationally merge mutually shared and mutually absent information and do not exploit all the information incorporated within the standard 2 ?? 2 contingency table; therefore, the commonly used formulae for such coefficients are more complicated than the actual range of values produced. Other coefficients do differentiate between mutual presences and absences; however, a number of these coefficients do not demonstrate a linear relationship to matrix sparseness. Finally, simulations using nonrandom matrices with known degrees of row-by-row similarities signify that several coefficients either do not display a reasonable range of values or are nonlinear with respect to known relationships within the data. Analyses with nonrandom matrices yield clues as to the utility of certain coefficients for specific applications. For example, coefficients such as Jaccard, Dice, and Baroni-Urbani and Buser are useful if correction of sparseness is desired, whereas the Russell-Rao coefficient is useful when sparseness correction is not desired. ?? 1989 International Association for Mathematical Geology.

Discourse analysis: Conversational analysis of the internal conversation in Oracle Corporation Malaysia

Directory of Open Access Journals (Sweden)

Marwa Marwa

2017-07-01

Full Text Available This study highlights the internal conversation which takes place in Oracle CorporationMalaysia. Through the study, it will be shown how conversational analysis is used toanalyze the transcription of a telephone conversation between Oracle staffs. The analysisof the transcriptions will apply a few basic concepts of conversational analysis; turntakingorganization, and the adjacency pair. The objective of the study is to find out howthe internal conversations takes place by focusing on the conversation itself, that is, theconversational structures spontaneously produced by people during talk ranging fromturn-taking strategies, how topics are introduced, conversation closings and so on. Bylooking in detail at such talk, we can gain a detailed understanding of how the staffs seethemselves in relation to the company that influence their daily lives.Keywords: conversational analysis, turn-taking, adjacency pairs

Apparatus and method for enabling quantum-defect-limited conversion efficiency in cladding-pumped Raman fiber lasers

Science.gov (United States)

Heebner, John E.; Sridharan, Arun K.; Dawson, Jay Walter; Messerly, Michael J.; Pax, Paul H.

2016-09-20

Cladding-pumped Raman fiber lasers and amplifiers provide high-efficiency conversion efficiency at high brightness enhancement. Differential loss is applied to both single-pass configurations appropriate for pulsed amplification and laser oscillator configurations applied to high average power cw source generation.

Introduction to differential equations with dynamical systems

CERN Document Server

Campbell, Stephen L

2011-01-01

Many textbooks on differential equations are written to be interesting to the teacher rather than the student. Introduction to Differential Equations with Dynamical Systems is directed toward students. This concise and up-to-date textbook addresses the challenges that undergraduate mathematics, engineering, and science students experience during a first course on differential equations. And, while covering all the standard parts of the subject, the book emphasizes linear constant coefficient equations and applications, including the topics essential to engineering students. Stephen Campbell and Richard Haberman--using carefully worded derivations, elementary explanations, and examples, exercises, and figures rather than theorems and proofs--have written a book that makes learning and teaching differential equations easier and more relevant. The book also presents elementary dynamical systems in a unique and flexible way that is suitable for all courses, regardless of length.

Investigation of the Buckling-Reactivity Conversion Coefficient using SRAC and MVP codes for UO2 Lattices in TCA experiments

International Nuclear Information System (INIS)

Le Dai Dien

2008-01-01

Benchmark experiments for International Reactor Physics Benchmark Experiments (IRPhE) Project carried out at TCA, the temperature effects on reactivity were studied for light water moderated and reflected UO 2 cores with/without soluble poisons. The buckling coefficient method using the measured critical water levels was proposed by Suzaki et al. The temperature dependence of buckling coefficient of reactivity and its variance by the core configurations of the benchmark experiments was investigated using SRAC and MVP calculations. From the calculations by SRAC as well as by MVP it is seen that the K-value can be taken as an average value only for each core with temperature changes which are considered as perturbation parameter. The difference between our calculations and benchmark results which uses constant K-value for all cores proves that the results depend on K-value and it play important role in defining reactivity effect using the water level worth method. (author)

Global stability of almost periodic solution of shunting inhibitory cellular neural networks with variable coefficients

International Nuclear Information System (INIS)

Chen Ling; Zhao Hongyong

2008-01-01

The paper investigates the almost periodicity of shunting inhibitory cellular neural networks with delays and variable coefficients. Several sufficient conditions are established for the existence and globally exponential stability of almost periodic solutions by employing fixed point theorem and differential inequality technique. The results of this paper are new and they complement previously known results

New type side weir discharge coefficient simulation using three novel hybrid adaptive neuro-fuzzy inference systems

Science.gov (United States)

Bonakdari, Hossein; Zaji, Amir Hossein

2018-03-01

In many hydraulic structures, side weirs have a critical role. Accurately predicting the discharge coefficient is one of the most important stages in the side weir design process. In the present paper, a new high efficient side weir is investigated. To simulate the discharge coefficient of these side weirs, three novel soft computing methods are used. The process includes modeling the discharge coefficient with the hybrid Adaptive Neuro-Fuzzy Interface System (ANFIS) and three optimization algorithms, namely Differential Evaluation (ANFIS-DE), Genetic Algorithm (ANFIS-GA) and Particle Swarm Optimization (ANFIS-PSO). In addition, sensitivity analysis is done to find the most efficient input variables for modeling the discharge coefficient of these types of side weirs. According to the results, the ANFIS method has higher performance when using simpler input variables. In addition, the ANFIS-DE with RMSE of 0.077 has higher performance than the ANFIS-GA and ANFIS-PSO methods with RMSE of 0.079 and 0.096, respectively.

Chronic subjective dizziness versus conversion disorder: discussion of clinical findings and rehabilitation.

Science.gov (United States)

Honaker, Julie A; Gilbert, Jane M; Staab, Jeffrey P

2010-06-01

Audiologists frequently encounter patients who complain of chronic dizziness or imbalance, in the absence of active vestibular or neurological deficits. Knowledge about conditions that cause this clinical presentation will allow audiologists to make important contributions to accurate diagnosis and effective management of these patients. This article reviews 2 such conditions, chronic subjective dizziness (CSD) and conversion disorder. A case of CSD and another of conversion disorder are presented, with a literature review of their clinical presentations, key diagnostic features, and treatment strategies. The role of the audiologist in assessing patients with these conditions and facilitating appropriate treatment referrals is discussed. The audiologist is in a key position to identify individuals with CSD and conversion disorder, 2 conditions that can be effectively managed if properly recognized. The authors demonstrate an effective team approach program that includes the audiologist's contribution to differential diagnosis, education of patients and other clinicians about these conditions, and development of recommendations for neurological, psychiatric, otologic, and physical therapy referrals.

Magnetic power conversion with machines containing full or porous wheel heat exchangers

Science.gov (United States)

Egolf, Peter W.; Kitanovski, Andrej; Diebold, Marc; Gonin, Cyrill; Vuarnoz, Didier

2009-04-01

A first part of the article contains a thermodynamic theory describing the temperature distribution in a Curie wheel. The occurring nonlinear ordinary differential equation has an analytical solution. If a Curie wheel is stabilized by levitation, it is named Palmy wheel. These wheels show a full structure, and because of this reason, their uptake of heat from a flame (Curie wheel) or by (solar) light absorption (Palmy wheel) only on the periphery of a cylinder is very limited. To improve the method, a modification of the principle by introducing a convective heat transport into a porous wheel is discussed. By this the power conversion rate from a heat flux to mechanical and electric power is very much increased. The second part of the article presents results of a theoretical/numerical study on the efficiencies of magnetic power conversion plants operating with porous wheels. Furthermore, these efficiencies—which are promising—are compared with those of existing power conversion plants, as e.g. geothermal binary cycle power plants.

Magnetic power conversion with machines containing full or porous wheel heat exchangers

International Nuclear Information System (INIS)

Egolf, Peter W.; Kitanovski, Andrej; Diebold, Marc; Gonin, Cyrill; Vuarnoz, Didier

2009-01-01

A first part of the article contains a thermodynamic theory describing the temperature distribution in a Curie wheel. The occurring nonlinear ordinary differential equation has an analytical solution. If a Curie wheel is stabilized by levitation, it is named Palmy wheel. These wheels show a full structure, and because of this reason, their uptake of heat from a flame (Curie wheel) or by (solar) light absorption (Palmy wheel) only on the periphery of a cylinder is very limited. To improve the method, a modification of the principle by introducing a convective heat transport into a porous wheel is discussed. By this the power conversion rate from a heat flux to mechanical and electric power is very much increased. The second part of the article presents results of a theoretical/numerical study on the efficiencies of magnetic power conversion plants operating with porous wheels. Furthermore, these efficiencies-which are promising-are compared with those of existing power conversion plants, as e.g. geothermal binary cycle power plants

Large deformation and mechanics of flexible isotropic membrane ballooning in three dimensions by differential quadrature method

International Nuclear Information System (INIS)

Mozaffari, M.; Atai, A. A.; Mostafa, N.

2009-01-01

This paper presents a computationally efficient and accurate new methodology in the differential quadrature analysis of structural mechanics for flexible membranes ballooning in three dimensions under a negative air pressure differential. The differential quadrature method is employed to discretize the resulting equations in the axial direction as well as for the solution procedure. The weighting coefficients employed are not exclusive, and any accurate and efficient method such as the generalized differential quadrature method may be used to produce the methods weighting coefficients. A second-order paraboloid of revolution is assumed to describe the ballooning shape. This study asserts the accuracy, convergency, and efficiency of the methodology by solving some typical stability, straining analysis membrane problems, and comparing the results with those of the exact solutions and/or those of physical tests

Large deformation and mechanics of flexible isotropic membrane ballooning in three dimensions by differential quadrature method

Energy Technology Data Exchange (ETDEWEB)

Mozaffari, M.; Atai, A. A.; Mostafa, N. [Islamic Azad University, Karaj (Iran, Islamic Republic of)

2009-11-15

This paper presents a computationally efficient and accurate new methodology in the differential quadrature analysis of structural mechanics for flexible membranes ballooning in three dimensions under a negative air pressure differential. The differential quadrature method is employed to discretize the resulting equations in the axial direction as well as for the solution procedure. The weighting coefficients employed are not exclusive, and any accurate and efficient method such as the generalized differential quadrature method may be used to produce the methods weighting coefficients. A second-order paraboloid of revolution is assumed to describe the ballooning shape. This study asserts the accuracy, convergency, and efficiency of the methodology by solving some typical stability, straining analysis membrane problems, and comparing the results with those of the exact solutions and/or those of physical tests

Systems of Differential Equations with Skew-Symmetric, Orthogonal Matrices

Science.gov (United States)

Glaister, P.

2008-01-01

The solution of a system of linear, inhomogeneous differential equations is discussed. The particular class considered is where the coefficient matrix is skew-symmetric and orthogonal, and where the forcing terms are sinusoidal. More general matrices are also considered.

Genetic differentiation and gene flow between the Tunisian ovine ...

African Journals Online (AJOL)

Haifa

Sheep is an important livestock species of Tunisia. They contribute greatly ... Genetic differentiation coefficient (Gst) over all loci was 0.1922, the fixation index [Fst by Analysis of molecular variance ..... their first cross with the D'Man. Anim. Res.

PC analysis of stochastic differential equations driven by Wiener noise

KAUST Repository

Le Maitre, Olivier; Knio, Omar

2015-01-01

A polynomial chaos (PC) analysis with stochastic expansion coefficients is proposed for stochastic differential equations driven by additive or multiplicative Wiener noise. It is shown that for this setting, a Galerkin formalism naturally leads

Calculation of photon attenuation coefficients of elements and compounds from approximate semi-analytical formulae

International Nuclear Information System (INIS)

Roteta, M.; Baro, J.; Fernandez-Varea, J.M.; Salvat, F.

1994-01-01

The FORTRAN 77 code PHOTAC to compute photon attenuation coefficients of elements and compounds is described. The code is based on the semi-analytical approximate atomic cross sections proposed by Baro et al. (1994). Photoelectric cross sections are calculated directly from a simple analytical expression. Atomic cross sections for coherent and incoherent scattering and for pair production are obtained as integrals of the corresponding differential cross sections. These integrals are evaluated, to a pre-selected accuracy, by using a 20-point Gauss adaptive integration algorithm. Calculated attenuation coefficients agree with recently compiled databases to within equal 1%, in the energy range from 1 KeV to 1 GeV. The complete source listing of the program PHOTAC is included

Converting differential-equation models of biological systems to membrane computing.

Science.gov (United States)

Muniyandi, Ravie Chandren; Zin, Abdullah Mohd; Sanders, J W

2013-12-01

This paper presents a method to convert the deterministic, continuous representation of a biological system by ordinary differential equations into a non-deterministic, discrete membrane computation. The dynamics of the membrane computation is governed by rewrite rules operating at certain rates. That has the advantage of applying accurately to small systems, and to expressing rates of change that are determined locally, by region, but not necessary globally. Such spatial information augments the standard differentiable approach to provide a more realistic model. A biological case study of the ligand-receptor network of protein TGF-β is used to validate the effectiveness of the conversion method. It demonstrates the sense in which the behaviours and properties of the system are better preserved in the membrane computing model, suggesting that the proposed conversion method may prove useful for biological systems in particular. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Frontal Conversion and Uniformity in 3D Printing by Photopolymerisation.

Science.gov (United States)

Vitale, Alessandra; Cabral, João T

2016-09-07

We investigate the impact of the non-uniform spatio-temporal conversion, intrinsic to photopolymerisation, in the context of light-driven 3D printing of polymers. The polymerisation kinetics of a series of model acrylate and thiol-ene systems, both neat and doped with a light-absorbing dye, is investigated experimentally and analysed according to a descriptive coarse-grained model for photopolymerisation. In particular, we focus on the relative kinetics of polymerisation with those of 3D printing, by comparing the evolution of the position of the conversion profile ( z f ) to the sequential displacement of the object stage ( ∆z ). After quantifying the characteristic sigmoidal monomer-to-polymer conversion of the various systems, with a combination of patterning experiments, FT-IR mapping, and modelling, we compute representative regimes for which z f is smaller, commensurate with, or larger than ∆z . While non-monotonic conversion can be detrimental to 3D printing, for instance in causing differential shrinkage of inhomogeneity in material properties, we identify opportunities for facile fabrication of modulated materials in the z -direction (i.e., along the illuminated axis). Our simple framework and model, based on directly measured parameters, can thus be employed in photopolymerisation-based 3D printing, both in process optimisation and in the precise design of complex, internally stratified materials by coupling the z -stage displacement and frontal polymerisation kinetics.

Frontal Conversion and Uniformity in 3D Printing by Photopolymerisation

Directory of Open Access Journals (Sweden)

Alessandra Vitale

2016-09-01

Full Text Available We investigate the impact of the non-uniform spatio-temporal conversion, intrinsic to photopolymerisation, in the context of light-driven 3D printing of polymers. The polymerisation kinetics of a series of model acrylate and thiol-ene systems, both neat and doped with a light-absorbing dye, is investigated experimentally and analysed according to a descriptive coarse-grained model for photopolymerisation. In particular, we focus on the relative kinetics of polymerisation with those of 3D printing, by comparing the evolution of the position of the conversion profile (zf to the sequential displacement of the object stage (∆z. After quantifying the characteristic sigmoidal monomer-to-polymer conversion of the various systems, with a combination of patterning experiments, FT-IR mapping, and modelling, we compute representative regimes for which zf is smaller, commensurate with, or larger than ∆z. While non-monotonic conversion can be detrimental to 3D printing, for instance in causing differential shrinkage of inhomogeneity in material properties, we identify opportunities for facile fabrication of modulated materials in the z-direction (i.e., along the illuminated axis. Our simple framework and model, based on directly measured parameters, can thus be employed in photopolymerisation-based 3D printing, both in process optimisation and in the precise design of complex, internally stratified materials by coupling the z-stage displacement and frontal polymerisation kinetics.

Recurrence relations between transformation coefficients of hyperspherical harmonics and their application to Moshinsky coefficients

International Nuclear Information System (INIS)

Raynal, J.

1976-01-01

Closed formulae and recurrence relations for the transformation of a two-body harmonic oscillator wave function to the hyperspherical formalism are given. With them Moshinsky or Smirnov coefficients are obtained from the transformation coefficients of hyperspheric harmonics. For these coefficients the diagonalization method of Talman and Lande reduces to simple recurrence relations which can be used directly to compute them. New closed formulae for these coefficients are also derived: they are needed to compute the two simplest coefficients which determine the sign for the recurrence relation. (Auth.)

Hopf bifurcation formula for first order differential-delay equations

Science.gov (United States)

Rand, Richard; Verdugo, Anael

2007-09-01

This work presents an explicit formula for determining the radius of a limit cycle which is born in a Hopf bifurcation in a class of first order constant coefficient differential-delay equations. The derivation is accomplished using Lindstedt's perturbation method.

COMPARISON THEOREM OF BACKWARD DOUBLY STOCHASTIC DIFFERENTIAL EQUATIONS

Institute of Scientific and Technical Information of China (English)

无

2010-01-01

This paper is devoted to deriving a comparison theorem of solutions to backward doubly stochastic differential equations driven by Brownian motion and backward It-Kunita integral. By the application of this theorem, we give an existence result of the solutions to these equations with continuous coefficients.

Comparison of field-measured radon diffusion coefficients with laboratory-measured coefficients

International Nuclear Information System (INIS)

Lepel, E.A.; Silker, W.B.; Thomas, V.W.; Kalkwarf, D.R.

1983-04-01

Experiments were conducted to compare radon diffusion coefficients determined for 0.1-m depths of soils by a steady-state method in the laboratory and diffusion coefficients evaluated from radon fluxes through several-fold greater depths of the same soils covering uranium-mill tailings. The coefficients referred to diffusion in the total pore volume of the soils and are equivalent to values for the quantity, D/P, in the Generic Environmental Impact Statement on Uranium Milling prepared by the US Nuclear Regulatory Commission. Two soils were tested: a well-graded sand and an inorganic clay of low plasticity. For the flux evaluations, radon was collected by adsorption on charcoal following passive diffusion from the soil surface and also from air recirculating through an aluminum tent over the soil surface. An analysis of variance in the flux evaluations showed no significant difference between these two collection methods. Radon diffusion coefficients evaluated from field data were statistically indistinguishable, at the 95% confidence level, from those measured in the laboratory; however, the low precision of the field data prevented a sensitive validation of the laboratory measurements. From the field data, the coefficients were calculated to be 0.03 +- 0.03 cm 2 /s for the sand cover and 0.0036 +- 0.0004 cm 2 /s for the clay cover. The low precision in the coefficients evaluated from field data was attributed to high variation in radon flux with time and surface location at the field site

Analytic expressions for mode conversion in a plasma with a parabolic density profile: Generalized results

International Nuclear Information System (INIS)

Hinkel-Lipsker, D.E.; Fried, B.D.; Morales, G.J.

1993-01-01

This study provides an analytic solution to the general problem of mode conversion in an unmagnetized plasma. Specifically, an electromagnetic wave of frequency ω propagating through a plasma with a parabolic density profile of scale length L p is examined. The mode conversion points are located a distance Δ 0 from the peak of the profile, where the electron plasma frequency ω p (z) matches the wave frequency ω. The corresponding reflection, transmission, and mode conversion coefficients are expressed analytically in terms of parabolic cylinder functions for all values of Δ 0 . The method of solution is based on a source approximation technique that is valid when the electromagnetic and electrostatic scale lengths are well separated. For large Δ 0 , i.e., (cL p /ω) 1/2 much-lt Δ 0 p , the appropriately scaled result [D. E. Hinkel-Lipsker et al., Phys. Fluids B 4, 559 (1992)] for a linear density profile is recovered as the parabolic cylinder functions asymptotically become Airy functions. When Δ 0 →0, the special case of conversion at the peak of the profile [D. E. Hinkel-Lipsker et al., Phys. Fluids B 4, 1772 (1992)] is obtained

Parametric study of up-conversion efficiency in Er-doped ceria nanoparticles under 780 nm excitation

International Nuclear Information System (INIS)

Shehata, N.; Kandas, I.; Samir, E.; Meehan, K.; Aldacher, M.

2016-01-01

This paper presents a new parametric study of the optical up-conversion process in ceria nanoparticles doped with erbium (Er-CeO 2 NPs). Under 780 nm excitation, both the possible transitions that occur between Er 3+ ions and up-conversion rate model simulation are presented. Ceria nanoparticles (CeO 2 NPs) doped with erbium are experimentally synthesized using chemical precipitation technique with post-annealing up to 900 °C with different weight ratios of erbium dopant. We found that the synthesized nanoparticles can emit both green and red emissions under 780 nm laser excitation via two-photon absorption mechanism. Then, the quantum efficiencies of both colored emissions are theoretically investigated with different parameters related to the optical conversion process and the studied material. In addition, this work offer suggested ranges for the optimum values of the studied parameters which could improve the quantum yield efficiency. Einstein coefficients for erbium hosted in ceria are discussed in details using Judd–Ofelt analysis. This promising study could be helpful in improving the up-conversion efficiency of Er-ceria nanoparticles for applications such as bio-imaging and optical-based sensors.

A parameterization scheme for the x-ray linear attenuation coefficient and energy absorption coefficient.

Science.gov (United States)

Midgley, S M

2004-01-21

A novel parameterization of x-ray interaction cross-sections is developed, and employed to describe the x-ray linear attenuation coefficient and mass energy absorption coefficient for both elements and mixtures. The new parameterization scheme addresses the Z-dependence of elemental cross-sections (per electron) using a simple function of atomic number, Z. This obviates the need for a complicated mathematical formalism. Energy dependent coefficients describe the Z-direction curvature of the cross-sections. The composition dependent quantities are the electron density and statistical moments describing the elemental distribution. We show that it is possible to describe elemental cross-sections for the entire periodic table and at energies above the K-edge (from 6 keV to 125 MeV), with an accuracy of better than 2% using a parameterization containing not more than five coefficients. For the biologically important elements 1 coefficients. At higher energies, the parameterization uses fewer coefficients with only two coefficients needed at megavoltage energies.

Segregation of chlorine in n-type tin monosulfide ceramics: Actual chlorine concentration for carrier-type conversion

Science.gov (United States)

Iguchi, Yuki; Sugiyama, Taiki; Inoue, Kazutoshi; Yanagi, Hiroshi

2018-05-01

Tin monosulfide (SnS) is an attractive material for photovoltaic cells because of its suitable band-gap energy, high absorption coefficient, and non-toxic and abundant constituent elements. The primary drawback of this material is the lack of n-type SnS. We recently demonstrated n-type SnS by doping with Cl. However, the Cl-doped n-type SnS bulk ceramics exhibited an odd behavior in which carrier-type conversion but not electron carrier concentration depended on the Cl concentration. In this study, the electron probe microanalysis (EPMA) elemental mapping of Cl-doped SnS revealed continuous homogeneous regions with a relatively low Cl concentration along with the islands of high Cl concentration in which Sn/S is far from unity. The difference between the Cl concentration in the homogeneous region (determined by EPMA) and the bulk Cl concentration (determined by wavelength-dispersive X-ray fluorescence spectroscopy) increased with the increasing Cl doping amount. The carrier concentration and the Hall coefficient clearly depended on the Cl concentration in the homogeneous region. Carrier-type conversion was observed at the Cl concentration of 0.26 at. % (in the homogeneous region).

A graphical method for estimating the tunneling factor for mode conversion processes

International Nuclear Information System (INIS)

Swanson, D.G.

1994-01-01

The fundamental parameter characterizing the strength of any mode conversion process is the tunneling parameter, which is typically determined from a model dispersion relation which is transformed into a differential equation. Here a graphical method is described which gives the tunneling parameter from quantities directly measured from a simple graph of the dispersion relation. The accuracy of the estimate depends only on the accuracy of the measurements

Efficiency analysis of straight fin with variable heat transfer coefficient and thermal conductivity

International Nuclear Information System (INIS)

Sadri, Somayyeh; Raveshi, Mohammad Reza; Amiri, Shayan

2012-01-01

In this study, one type of applicable analytical method, differential transformation method (DTM), is used to evaluate the efficiency and behavior of a straight fin with variable thermal conductivity and heat transfer coefficient. Fins are widely used to enhance heat transfer between primary surface and the environment in many industrial applications. The performance of such a surface is significantly affected by variable thermal conductivity and heat transfer coefficient, particularly for large temperature differences. General heat transfer equation related to the fin is derived and dimensionalized. The concept of differential transformation is briefly introduced, and then this method is employed to derive solutions of nonlinear equations. Results are evaluated for several cases such as: laminar film boiling or condensation, forced convection, laminar natural convection, turbulent natural convection, nucleate boiling, and radiation. The obtained results from DTM are compared with the numerical solution to verify the accuracy of the proposed method. The effects of design parameters on temperature and efficiency are evaluated by some figures. The major aim of the present study, which is exclusive for this article, is to find the effect of the modes of heat transfer on fin efficiency. It has been shown that for radiation heat transfer, thermal efficiency reaches its maximum value

Revealing Layers of Pristine Oriented Crystals Embedded Within Deep Ice Clouds Using Differential Reflectivity and the Copolar Correlation Coefficient

Science.gov (United States)

Keat, W. J.; Westbrook, C. D.

2017-11-01

Pristine ice crystals typically have high aspect ratios (≫ 1), have a high density and tend to fall preferentially with their major axis aligned horizontally. Consequently, they can, in certain circumstances, be readily identified by measurements of differential reflectivity (ZDR), which is related to their average aspect ratio. However, because ZDR is reflectivity weighted, its interpretation becomes ambiguous in the presence of even a few, larger aggregates or irregular polycrystals. An example of this is in mixed-phase regions that are embedded within deeper ice cloud. Currently, our understanding of the microphysical processes within these regions is hindered by a lack of good observations. In this paper, a novel technique is presented that removes this ambiguity using measurements from the 3 GHz Chilbolton Advanced Meteorological Radar in Southern England. By combining measurements of ZDR and the copolar correlation coefficient (ρhv), we show that it is possible to retrieve both the relative contribution to the radar signal and "intrinsic" ZDR (ZDRIP) of the pristine oriented crystals, even in circumstances where their signal is being masked by the presence of aggregates. Results from two case studies indicate that enhancements in ZDR embedded within deep ice clouds are typically produced by pristine oriented crystals with ZDRIP values between 3 and 7 dB (equivalent to 5-9 dB at horizontal incidence) but with varying contributions to the radar reflectivity. Vertically pointing 35 GHz cloud radar Doppler spectra and in situ particle images from the Facility for Airborne Atmospheric Measurements BAe-146 aircraft support the conceptual model used and are consistent with the retrieval interpretation.

Self-Biased Differential Rectifier with Enhanced Dynamic Range for Wireless Powering

KAUST Repository

Ouda, Mahmoud H.; Khalil, Waleed; Salama, Khaled N.

2016-01-01

A self-biased, cross-coupled, differential rectifier is proposed with enhanced power-conversion efficiency over an extended range of input power. A prototype is designed for UHF 433MHz RF power-harvesting applications and is implemented using 0.18μm

Uranium conversion; Urankonvertering

Energy Technology Data Exchange (ETDEWEB)

Oliver, Lena; Peterson, Jenny; Wilhelmsen, Katarina [Swedish Defence Research Agency (FOI), Stockholm (Sweden)

2006-03-15

FOI, has performed a study on uranium conversion processes that are of importance in the production of different uranium compounds in the nuclear industry. The same conversion processes are of interest both when production of nuclear fuel and production of fissile material for nuclear weapons are considered. Countries that have nuclear weapons ambitions, with the intention to produce highly enriched uranium for weapons purposes, need some degree of uranium conversion capability depending on the uranium feed material available. This report describes the processes that are needed from uranium mining and milling to the different conversion processes for converting uranium ore concentrate to uranium hexafluoride. Uranium hexafluoride is the uranium compound used in most enrichment facilities. The processes needed to produce uranium dioxide for use in nuclear fuel and the processes needed to convert different uranium compounds to uranium metal - the form of uranium that is used in a nuclear weapon - are also presented. The production of uranium ore concentrate from uranium ore is included since uranium ore concentrate is the feed material required for a uranium conversion facility. Both the chemistry and principles or the different uranium conversion processes and the equipment needed in the processes are described. Since most of the equipment that is used in a uranium conversion facility is similar to that used in conventional chemical industry, it is difficult to determine if certain equipment is considered for uranium conversion or not. However, the chemical conversion processes where UF{sub 6} and UF{sub 4} are present require equipment that is made of corrosion resistant material.

Apparent diffusion coefficients of breast tumors. Clinical application

International Nuclear Information System (INIS)

Hatakenaka, Masamitsu; Soeda, Hiroyasu; Yabuuchi, Hidetake; Matsuo, Yoshio; Kamitani, Takeshi; Oda, Yoshinao; Tsuneyoshi, Masazumi; Honda, Hiroshi

2008-01-01

The purpose of this study was to evaluate the usefulness of apparent diffusion coefficient (ADC) for the differential diagnosis of breast tumors and to determine the relation between ADC and tumor cellularity. One hundred and thirty-six female patients (age range, 17-83 years; average age, 51.7 years) with 140 histologically proven breast tumors underwent diffusion-weighted magnetic resonance (MR) imaging (DWI) using the spin-echo echo-planar technique, and the ADCs of the tumors were calculated using 3 different b values, 0, 500, and 1000 s/mm 2 . The diagnoses consisted of fibroadenoma (FA, n=16), invasive ductal carcinoma, not otherwise specified (IDC, n=117), medullary carcinoma (ME, n=3) and mucinous carcinoma (MU, n=4). Tumor cellularity was calculated from surgical specimens. The ADCs of breast tumors and cellularity were compared between different histological types by analysis of variance and Scheffe's post hoc test. The correlation between tumor cellularity and ADC was analyzed by Pearson correlation test. Significant differences were observed in ADCs between FA and all types of cancers (P 2 =0.451). The ADC may potentially help in differentiating benign and malignant breast tumors. Tumor ADC correlates inversely with tumor cellularity. (author)

The diagnostic value of diffusion-weighted imaging and the apparent diffusion coefficient values in the differentiation of benign and malignant breast lesions

International Nuclear Information System (INIS)

Çabuk, Gonca; Duce, Meltem Nass; Özgür, Anil; Apaydin, Feramuz Demir; Polat, Ayşe; Orekici, Gülhan

2015-01-01

The goal of our study was to evaluate the diagnostic efficacy of diffusion-weighted imaging (DWI) in the differentiation of benign and malignant breast lesions. Between June 2012 and March 2013, 60 patients with 63 lesions (age range 29-70 years, mean age 48.6 years) were included in our study. All lesions, except complicated cysts and intra-mammary lymph nodes, were confirmed histopathologically. The patients were evaluated with a 1.5 Tesla MR scanner using dedicated bilateral breast coil. DWI images were obtained by echo planar imaging sequence and 'b' values were selected as 200, 600 and 1000 s/mm2. Apparent diffusion coefficient (ADC) values of both breast lesions and the normal fibroglandular tissue of the contralateral breast were calculated and statistically compared using Shapiro-Wilk test, Student's t-test, Mann-Whitney U test, chi-square test and the receiver operating curve. Of 63 lesions, 22 were malignant and 41 were benign. In malignant lesions, the mean ADC values were 1.40 ± 0.41 × 10 −3 mm 2 /s for b = 200, 1.05 ± 0.28 × 10 −3 mm 2 /s for b = 600 and 0.91 ± 0.20 × 10 −3 mm 2 /s for b = 1000 and in benign lesions, the mean ADC values were 2.13 ± 0.85 × 10 −3 mm 2 /s for b = 200, 1.64 ± 0.47 × 10 −3 mm 2 /s for b = 600 and 1.40 ± 0.43 × 10 −3 mm 2 /s for b = 1000. The success of ADC values in differentiation of benign and malignant lesions was statistically significant (P = 0.0001). The threshold values were determined to be 1.50 × 10 −3 mm 2 /s for b = 200, 1.22 × 10 −3 mm 2 /s for b = 600 and 0.98 × 10 −3 mm 2 /s for b = 1000 (P < 0.05). DWI can be an effective radiological method in the differentiation of benign and malignant breast lesions.

Growth of meromorphic solutions of higher-order linear differential equations

Directory of Open Access Journals (Sweden)

Wenjuan Chen

2009-01-01

Full Text Available In this paper, we investigate the higher-order linear differential equations with meromorphic coefficients. We improve and extend a result of M.S. Liu and C.L. Yuan, by using the estimates for the logarithmic derivative of a transcendental meromorphic function due to Gundersen, and the extended Winman-Valiron theory which proved by J. Wang and H.X. Yi. In addition, we also consider the nonhomogeneous linear differential equations.

Metal supported on natural zeolite as catalysts for conversion of ethanol to gasoline

Directory of Open Access Journals (Sweden)

Kristiani Anis

2017-01-01

Full Text Available A various of metal supported into natural zeolite was prepared via wet impregnation method. The transition metals impregnated are nickel, cobalt, copper and zinc. The catalytic properties both of physical and chemical properties were characterized by X-ray Diffraction (XRD, Thermo Gravimetri Analysis (TGA-Differential Scanning Calorimetry (DSC, Surface Area Analyzer-Porositymeter and also gravimetry method for acidity measurement following by the adsorption of organic bases. The results showed that different metals impregnated into natural zeolite affected physical and chemical properties, i.e. crystalinity, surface area, pore size, pore volume and acidity. Their catalytic activity was tested for conversion ethanol to gasoline and showed high conversion up to 80-90% with the aromatics as major product.

Some new results for recurrent neural networks with varying-time coefficients and delays

International Nuclear Information System (INIS)

Jiang Haijun; Teng Zhidong

2005-01-01

In this Letter, we consider the recurrent neural networks with varying-time coefficients and delays. By constructing new Lyapunov functional, introducing ingeniously many real parameters and applying the technique of Young inequality, we establish a series of criteria on the boundedness, global exponential stability and the existence of periodic solutions. In these criteria, we do not require that the response functions are differentiable, bounded and monotone nondecreasing. Some previous works are improved and extended

A novel method to solve functional differential equations

International Nuclear Information System (INIS)

Tapia, V.

1990-01-01

A method to solve differential equations containing the variational operator as the derivation operation is presented. They are called variational differential equations (VDE). The solution to a VDE should be a function containing the derivatives, with respect to the base space coordinates, of the fields up to a generic order s: a s-th-order function. The variational operator doubles the order of the function on which it acts. Therefore, in order to make compatible the orders of the different terms appearing in a VDE, the solution should be a function containing the derivatives of the fields at all orders. But this takes us again back to the functional methods. In order to avoid this, one must restrict the considerations, in the case of second-order VDEs, to the space of s-th-order functions on which the variational operator acts transitively. These functions have been characterized for a one-dimensional base space for the first- and second-order cases. These functions turn out to be polynomial in the highest-order derivatives of the fields with functions of the lower-order derivatives as coefficients. Then VDEs reduce to a system of coupled partial differential equations for the coefficients above mentioned. The importance of the method lies on the fact that the solutions to VDEs are in a one-to-one correspondence with the solutions of functional differential equations. The previous method finds direct applications in quantum field theory, where the Schroedinger equation plays a central role. Since the Schroedinger equation is reduced to a system of coupled partial differential equations, this provides a nonperturbative scheme for quantum field theory. As an example, the massless scalar field is considered

Phone Conversation while Processing Information: Chronometric Analysis of Load Effects in Everyday-media Multitasking

Science.gov (United States)

Steinborn, Michael B.; Huestegge, Lynn

2017-01-01

This is a pilot study that examined the effect of cell-phone conversation on cognition using a continuous multitasking paradigm. Current theorizing argues that phone conversation affects behavior (e.g., driving) by interfering at a level of cognitive processes (not peripheral activity) and by implying an attentional-failure account. Within the framework of an intermittent spare–utilized capacity threading model, we examined the effect of aspects of (secondary-task) phone conversation on (primary-task) continuous arithmetic performance, asking whether phone use makes components of automatic and controlled information-processing (i.e., easy vs. hard mental arithmetic) run more slowly, or alternatively, makes processing run less reliably albeit with the same processing speed. The results can be summarized as follows: While neither expecting a text message nor expecting an impending phone call had any detrimental effects on performance, active phone conversation was clearly detrimental to primary-task performance. Crucially, the decrement imposed by secondary-task (conversation) was not due to a constant slowdown but is better be characterized by an occasional breakdown of information processing, which differentially affected automatic and controlled components of primary-task processing. In conclusion, these findings support the notion that phone conversation makes individuals not constantly slower but more vulnerable to commit attention failure, and in this way, hampers stability of (primary-task) information processing. PMID:28634458

Phone Conversation while Processing Information: Chronometric Analysis of Load Effects in Everyday-media Multitasking

Directory of Open Access Journals (Sweden)

Michael B. Steinborn

2017-06-01

Full Text Available This is a pilot study that examined the effect of cell-phone conversation on cognition using a continuous multitasking paradigm. Current theorizing argues that phone conversation affects behavior (e.g., driving by interfering at a level of cognitive processes (not peripheral activity and by implying an attentional-failure account. Within the framework of an intermittent spare–utilized capacity threading model, we examined the effect of aspects of (secondary-task phone conversation on (primary-task continuous arithmetic performance, asking whether phone use makes components of automatic and controlled information-processing (i.e., easy vs. hard mental arithmetic run more slowly, or alternatively, makes processing run less reliably albeit with the same processing speed. The results can be summarized as follows: While neither expecting a text message nor expecting an impending phone call had any detrimental effects on performance, active phone conversation was clearly detrimental to primary-task performance. Crucially, the decrement imposed by secondary-task (conversation was not due to a constant slowdown but is better be characterized by an occasional breakdown of information processing, which differentially affected automatic and controlled components of primary-task processing. In conclusion, these findings support the notion that phone conversation makes individuals not constantly slower but more vulnerable to commit attention failure, and in this way, hampers stability of (primary-task information processing.

Phone Conversation while Processing Information: Chronometric Analysis of Load Effects in Everyday-media Multitasking.

Science.gov (United States)

Steinborn, Michael B; Huestegge, Lynn

2017-01-01

This is a pilot study that examined the effect of cell-phone conversation on cognition using a continuous multitasking paradigm. Current theorizing argues that phone conversation affects behavior (e.g., driving) by interfering at a level of cognitive processes (not peripheral activity) and by implying an attentional-failure account. Within the framework of an intermittent spare-utilized capacity threading model, we examined the effect of aspects of (secondary-task) phone conversation on (primary-task) continuous arithmetic performance, asking whether phone use makes components of automatic and controlled information-processing (i.e., easy vs. hard mental arithmetic) run more slowly, or alternatively, makes processing run less reliably albeit with the same processing speed. The results can be summarized as follows: While neither expecting a text message nor expecting an impending phone call had any detrimental effects on performance, active phone conversation was clearly detrimental to primary-task performance. Crucially, the decrement imposed by secondary-task (conversation) was not due to a constant slowdown but is better be characterized by an occasional breakdown of information processing, which differentially affected automatic and controlled components of primary-task processing. In conclusion, these findings support the notion that phone conversation makes individuals not constantly slower but more vulnerable to commit attention failure, and in this way, hampers stability of (primary-task) information processing.

Weyl q-coefficients for uq(3) and Racah q -coefficients for suq(2)

International Nuclear Information System (INIS)

Asherova, R.M.; Smirnov, Yu.F.; Tolstoy, V.N.

1996-01-01

With the aid of the projection-operator technique, the general analytic expression for the elements of the matrix that relates the U and T bases of an arbitrary finite-dimensional irreducible representation of the uq(3) quantum algebra (Weyl q-coefficients) is obtained for the case where the deformation parameter q is not equal to a square root of unity. The procedure for resummation of q-factorial expressions is used to prove that, modulo phase factors, these Weyl q-coefficients coincide with Racah q-coefficients for the suq(2) quantum algebra. It is also shown that, on the basis of one general formula, the q-analogs of all known general analytic expressions for the 6j symbols (and Racah coefficients) of the Lie algebras of the angular momentum can be obtained by using this resummation procedure. The symmetry properties of these q coefficients are discussed. The result is formulated in the following way: the general formulas for the q-6j symbols (Racah q-coefficients) of the suq(2) quantum algebra are obtained from the general formulas for the conventional 6j symbols (Racah coefficients) of the su(2) Lie algebra by replacing directly all factorials with q-factorials, the symmetry properties of the q-6j symbols being completely coincident with the symmetry properties of the conventional 6j symbols

Nanostructured Solar Irradiation Control Materials for Solar Energy Conversion

Science.gov (United States)

Kang, Jinho; Marshall, I. A.; Torrico, M. N.; Taylor, C. R.; Ely, Jeffry; Henderson, Angel Z.; Kim, J.-W.; Sauti, G.; Gibbons, L. J.; Park, C.;

Conversion of the reducing substances and the indices of sugar solutions

Directory of Open Access Journals (Sweden)

V. A. Golybin

2017-01-01

Full Text Available Investigated the extent of adsorption removal of calcium carbonate pigments - products of conversion of the reducing substances in different conditions of the preceding limestone processing flow. Also carried out experiments on the influence of the conditions of conversion of the reducing substances in the process of lime treatment on the filtration characteristics of the solutions after the first carbonation. As the criterion was accepted the value of the filtration coefficient. Found that by subjecting the conversion of reducing substances in the process managed lime processing, it is necessary in the course of the subsequent carbonization to ensure maximum adsorption of the formed secondary products – it is possible to achieve a satisfactory filtration of the investigated solutions. It is shown that the largest absolute removal of the dyes obtained after high temperature lime treatment, however, the composition of the products of disintegration to a greater extent accumulate high molecular weight compounds which deteriorate the filtration performance of solutions. In the solutions after the combination of the lime treatment in the process of carbonization is achieved the maximum effect of adsorption with the minimum remaining shares of conversion products, including high-molecular substances, which favorably affect the parameters of the filtering. The combination possibilities of the model of purification of diffusion juice with warm-hot lime treatment is limited to receive the filtered juice in the processing of raw materials with a purity of beet juice 82 % or less, you need to enter a 3.5% Cao, which is unacceptable. To ensure sustainable results of the adsorption of conversion products reducing substances and satisfactory filtering carbonated solutions are to intensify the processes of combined lime processing diffusion juice at the optimum distribution of the reagent.

Intravoxel Incoherent Motion Diffusion-weighted Imaging: Evaluation of the Differentiation of Solid Hepatic Lesions

Directory of Open Access Journals (Sweden)

Ma Luo

2017-10-01

Full Text Available PURPOSE: To evaluate whether intravoxel incoherent motion (IVIM–related parameters could be used to differentiate malignant from benign focal liver lesions (FLLs and to improve diagnostic efficiency. METHODS: Seventy-four patients with 75 lesions, including 51 malignant FLLs and 24 benign FLLs, underwent liver 3.0-T magnetic resonance imaging for routine examination sequences. IVIM diffusion-weighted imaging (DWI with 11 b values (0-800 s/mm2 was also acquired concurrently. Apparent diffusion coefficient (ADCtotal and IVIM-derived parameters, such as the pure diffusion coefficient (D, the pseudodiffusion coefficient (D⁎, and the perfusion fraction (f, were calculated and compared between the two groups. A receiver operating characteristic curve analysis was performed to assess their diagnostic value. RESULTS: ADCtotal, D, and f were significantly lower in the malignant group than in the benign group, whereas D⁎ did not show a statistical difference. D had a larger area under the curve value (0.968 and higher sensitivity (92.30% for differentiation. CONCLUSION: IVIM is a useful method to differentiate malignant and benign FLLs. The D value showed higher efficacy to detect hepatic solid lesions.

The Truth About Ballistic Coefficients

OpenAIRE

Courtney, Michael; Courtney, Amy

2007-01-01

The ballistic coefficient of a bullet describes how it slows in flight due to air resistance. This article presents experimental determinations of ballistic coefficients showing that the majority of bullets tested have their previously published ballistic coefficients exaggerated from 5-25% by the bullet manufacturers. These exaggerated ballistic coefficients lead to inaccurate predictions of long range bullet drop, retained energy and wind drift.

Advances in copper-chalcopyrite thin films for solar energy conversion

Energy Technology Data Exchange (ETDEWEB)

Kaneshiro, Jess; Gaillard, Nicolas; Rocheleau, Richard; Miller, Eric [Hawaii Natural Energy Institute, University of Hawaii at Manoa, 1680 East-West Road, Post 109, Honolulu, HI 96822 (United States)

2010-01-15

Promising alternatives to crystalline silicon as the basic building block of solar cells include copper-chalcopyrite thin films such as copper indium gallium diselenide, a class of thin films exhibiting bandgap-tunable semiconductor behavior, direct bandgaps and high absorption coefficients. These properties allow for the development of novel solar-energy conversion configurations like ultra-high efficiency multi-junction solar cells utilizing combinations of photovoltaic and photoelectrochemical junctions for hydrogen production. This paper discusses the current worldwide status as well as the development and optimization of copper-chalcopyrite thin films deposited onto various substrate types for different photovoltaic and photoelectrochemical applications at the Hawaii Natural Energy Institute. (author)

Physics and safety studies of a low conversion ratio sodium cooled fast reactor

International Nuclear Information System (INIS)

Cahalan, J. E.; Smith, M. A.; Hill, R. N.; Dunn, F. E.

2004-01-01

This paper explores the feasibility of a compact fast burner reactor that can achieve a low transuranic conversion ratio. The major design option considered is the reduction of fissile breeding by the removal of fertile material from the fast reactor system. Reductions in the fuel pin diameter and thus fuel loading were employed to remove fertile material. Reactor performance parameters and reactivity coefficients were evaluated for a compact core design with a targeted conversion ratio of 0.25. To assess the safety implications, a detailed transient analysis model was employed using the SAS4A/SASSYS-1 computer code. A series of calculations was performed to assess the behavior of the reactor and plant in an unprotected loss-of-flow accident (ULOF). A parametric study was also carried out using increasingly conservative modeling assumptions. The computational results show that for nominal, best-estimate analysis assumptions and input data, the low conversion ratio reactor design responds to the ULOF with a very high level of self-protection. Both short-term and long-term quasi-equilibrium reactor conditions predicted in the analysis indicate very large margins of safety. (authors)

Evaluation of radiation therapy for advanced well-differentiated thyroid carcinoma

International Nuclear Information System (INIS)

Tatsuno, Ikuo; Tada, Akira; Choto, Shuichi; Takanaka, Tsuyoshi

1987-01-01

Eighty-two patients with advanced well-differentiated thyroid carcinoma were treated. Sixty-six patients survived for more than 10 years and 10-year-survival rate was 80.5 %. Multidisciplinary treatment, consisting of surgery, radioiodine, external irradiation and TSH suppression was studied. We emphasized that radioiodine treatment after thyroid-ectomy was unique and an ideal therapeutic model for locally advanced, distant metastatic and recurrent cases as far as radioiodine was accumulated on thyroid cancer tissue. External irradiation was sometimes effective for the remnant thyroid carcinoma and metastases. Occassionally, well-differentiated thyroid carcinoma showed good response to TSH suppression therapy using thyroid hormone. The significance of conversion of well-differentiated carcinoma of thyroid to anaplastic carcinoma was noticed. We recognized that radiation therapy was effective for advanced well-differentiated thyroid carcinoma in multidisciplinary treatment. (author)

Evaluation of radiation therapy for advanced well-differentiated thyroid carcinoma

Energy Technology Data Exchange (ETDEWEB)

Tatsuno, Ikuo; Tada, Akira; Choto, Shuichi; Takanaka, Tsuyoshi

1987-02-01

Eighty-two patients with advanced well-differentiated thyroid carcinoma were treated. Sixty-six patients survived for more than 10 years and 10-year-survival rate was 80.5 %. Multidisciplinary treatment, consisting of surgery, radioiodine, external irradiation and TSH suppression was studied. We emphasized that radioiodine treatment after thyroid-ectomy was unique and an ideal therapeutic model for locally advanced, distant metastatic and recurrent cases as far as radioiodine was accumulated on thyroid cancer tissue. External irradiation was sometimes effective for the remnant thyroid carcinoma and metastases. Occassionally, well-differentiated thyroid carcinoma showed good response to TSH suppression therapy using thyroid hormone. The significance of conversion of well-differentiated carcinoma of thyroid to anaplastic carcinoma was noticed. We recognized that radiation therapy was effective for advanced well-differentiated thyroid carcinoma in multidisciplinary treatment.

Development of database on the distribution coefficient. 1. Collection of the distribution coefficient data

Energy Technology Data Exchange (ETDEWEB)

Takebe, Shinichi; Abe, Masayoshi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

2001-03-01

The distribution coefficient is very important parameter for environmental impact assessment on the disposal of radioactive waste arising from research institutes. The literature survey in the country was mainly carried out for the purpose of selecting the reasonable distribution coefficient value on the utilization of this value in the safety evaluation. This report was arranged much informations on the distribution coefficient for inputting to the database for each literature, and was summarized as a literature information data on the distribution coefficient. (author)

Galois action on solutions of a differential equation

NARCIS (Netherlands)

Hendriks, Peter A.; Put, Marius van der

Consider a second-order differential equation of the form y '' + ay' + by = O with a,b is an element of Q(x). Kovacic's algorithm tries to compute a solution of the associated Riccati equation that is algebraic and of minimal degree over (Q) over bar(x). The coefficients of the monic irreducible